Nuclear power spare part inventory management method, electronic equipment and computer program product

Abstract

The invention provides a nuclear power spare part inventory management method, electronic equipment and a computer program product. Relates to the technical field of spare part inventory management. In view of the problem that the actual guarantee capability of spare part inventory is overestimated and uncertain requirements cannot be effectively handled, the nuclear power spare part inventory management method provided by the invention comprises the steps of determining an inventory model type corresponding to nuclear power spare parts based on attribute characteristics of the nuclear power spare parts; based on the inventory parameters corresponding to the inventory model types, determining target nuclear power spare parts needing to set reorder points; on the basis of the receiving parameter and the purchasing parameter of the target nuclear power spare part, calculating a reorder point and a safe inventory corresponding to the target nuclear power spare part; wherein the inventory parameter comprises a reorder point; the safe stock is a subdivision item of the reorder point, and the safe stock is used for monitoring the storage rate of the safe stock and limiting the consumption of nuclear power spare parts. According to the embodiment of the invention, the refinement degree of spare part inventory management and the guarantee degree of spare parts in case of important demands can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of spare parts inventory management, and in particular to a nuclear power spare parts inventory management method, electronic equipment, and computer program product. Background Art

[0002] In the field of nuclear power, nuclear power plants store a large number of spare parts in their warehouses, which are used to repair faulty facilities when nuclear power unit facilities fail.

[0003] At present, maturely operated nuclear power units manage their spare parts inventory by setting inventory indicators such as critical component management (CCM) spare parts guarantee rate and CCM spare parts reserve rate.

[0004] However, the current inventory indicator setting method only counts the inventory available, which leads to an overestimation of the actual guarantee capacity of the spare parts inventory; or the reorder point indicator is mixed with the safety stock indicator, which makes some safety stock indicators set too low and unable to effectively respond to uncertain demand. Summary of the Invention

[0005] According to various embodiments of the present application, a nuclear power spare parts inventory management method, electronic equipment and computer program product are provided; the level of refinement in managing spare parts inventory and the level of guarantee for spare parts in times of critical demand can be improved.

[0006] In a first aspect, the present application provides a method for managing nuclear power spare parts inventory, the method comprising:

[0007] Based on the attribute characteristics of nuclear power spare parts, the inventory model type corresponding to the nuclear power spare parts is determined; based on the inventory parameters corresponding to the inventory model type, the target nuclear power spare parts for which a reorder point needs to be set are determined; based on the issuance parameters and procurement parameters of the target nuclear power spare parts, the reorder point and safety stock quantity corresponding to the target nuclear power spare parts are calculated; among which, the inventory parameters include the reorder point; the safety stock quantity is a subdivision of the reorder point, and the safety stock quantity is used to monitor the safety stock reserve rate of nuclear power spare parts and limit the issuance quantity of nuclear power spare parts.

[0008] Through the above method, nuclear power spare parts are classified based on their attribute characteristics, and the inventory model type to which the nuclear power spare parts belong is determined, thereby determining the nuclear power spare parts that need to set a reorder point based on the inventory model type; for nuclear power spare parts that need to set a reorder point, based on the corresponding collection parameters and procurement parameters of the nuclear power spare parts, the corresponding reorder point and safety stock quantity are calculated, and the setting values of the safety stock quantity sub-items are clearly set, thereby effectively monitoring the safety stock reserve rate based on the safety stock quantity, and at the same time, limiting the collection quantity of nuclear power spare parts based on the safety stock reserve rate, thereby improving the guarantee level of the collection demand of important spare parts; it has strong ease of use and practicality.

[0009] In a second aspect, the present application provides a nuclear power spare parts inventory management device, comprising:

[0010] A classification unit, configured to determine an inventory model type corresponding to a nuclear power spare part based on attribute characteristics of the nuclear power spare part;

[0011] An identification unit, configured to determine, based on inventory parameters corresponding to the inventory model type, target nuclear power spare parts for which a reorder point needs to be set;

[0012] A calculation unit is used to calculate the reorder point and safety stock corresponding to the target nuclear power spare parts based on the collection parameters and procurement parameters of the target nuclear power spare parts; wherein, the inventory parameters include the reorder point; the safety stock is a subdivision of the reorder point, and the safety stock is used to monitor the safety stock reserve rate of the nuclear power spare parts and limit the collection quantity of the nuclear power spare parts.

[0013] In a third aspect, the present application provides an electronic device comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements any one of the methods described in the first aspect when executing the computer program.

[0014] In a fourth aspect, the present application provides a computer-readable storage medium having a computer program stored thereon, and when the computer program is executed by a processor, the method according to any one of the first aspects is implemented.

[0015] In a fifth aspect, the present application provides a computer program product, which, when executed on a device, enables the device to execute any of the methods described in the first aspect.

[0016] It can be understood that the beneficial effects of the second to fifth aspects mentioned above can be found in the relevant description of the first aspect mentioned above, and will not be repeated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0018] Figure 1 A schematic diagram of the implementation flow of the nuclear power spare parts inventory management method provided in an embodiment of the present application;

[0019] Figure 2 A schematic diagram of spare parts classification is provided for the embodiment of the present application;

[0020] Figure 3 A schematic diagram illustrating the relationship between safety stock and reorder point provided in an embodiment of the present application;

[0021] Figure 4 A schematic diagram of a model selection process for low-turnover spare parts provided in an embodiment of the present application;

[0022] Figure 5 A schematic diagram of limiting the use of safety stock provided in an embodiment of the present application;

[0023] Figure 6 A schematic diagram of a flow chart for determining a demand distribution function for nuclear power spare parts according to an embodiment of the present application;

[0024] Figure 7 A schematic diagram of the classification of nuclear power plant spare parts provided in the embodiment of the present application;

[0025] Figure 8 A schematic diagram of the cumulative distribution probability under the demand distribution function provided in an embodiment of the present application;

[0026] Figure 9 A schematic diagram of the probability distribution of demand for a batch of spare parts for a nuclear power plant provided in an embodiment of the present application;

[0027] Figure 10 A schematic diagram showing the relationship between the reserve inventory and the expected availability rate provided in the embodiment of the present application;

[0028] Figure 11 A schematic diagram of the distribution of spare parts in stock before and after safety stock control provided in an embodiment of the present application;

[0029] Figure 12 A schematic diagram of the structure of a nuclear power spare parts inventory management device provided in an embodiment of the present application;

[0030] Figure 13 A schematic structural diagram of an electronic device is provided for an embodiment of the present application. DETAILED DESCRIPTION

[0031] The following embodiments of the technical solution of the present application will be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present application and are therefore only examples and are not intended to limit the scope of protection of the present application.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above-mentioned figure descriptions are intended to cover non-exclusive inclusions.

[0033] In the description of the embodiments of this application, the technical terms "first" and "second" are used only to distinguish different objects and should not be understood to indicate or imply relative importance or implicitly specify the quantity, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0034] References herein to "embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiments may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0035] In the description of the embodiments of this application, the term "and / or" is simply a description of the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent the following three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects are in an "or" relationship.

[0036] Currently, mature commercial units have set standards for a 100% guarantee rate for CCM spare parts (critical and sensitive spare parts) and a CCM spare parts reserve rate of ≥95%. In actual application scenarios, based on these standards, CCM spare parts are currently considered to be in reserve as long as they are in stock, regardless of whether the reserves meet the required inventory parameter settings. Furthermore, the CCM spare parts safety stock parameter is not differentiated from the reorder point, resulting in the safety stock parameter settings for some CCM spare parts being too low, making it ineffective in responding to uncertain demand.

[0037] Some related technologies often use different models based on spare parts classification to ensure unexpected demand. For example, a "ZB+EX+reorder point" inventory strategy is used to set a reorder point to ensure unexpected demand. This approach still does not differentiate between safety stock parameters. CCM spare parts guarantee rate statistics assume that only inventory is available, without considering minimum guaranteed quantities (such as the minimum replacement quantity for a spare part).

[0038] For example, the safety stock is set based on the "PD+EX+safety stock" inventory strategy, and the safety stock is used as a virtual reserve in the material requirement planning calculation. When the reorder point and safety stock are set at the same time, the reorder point is greater than the safety stock, and the safety stock does not participate in the calculation; when the spare parts inventory is actually set, the safety stock of the spare parts is not distinguished from the reorder point, and the value of the safety stock is included in the value of the reorder point, so that the relationship between the current inventory quantity and the safety stock cannot be effectively monitored, the safety stock reserve rate data of the spare parts cannot be obtained, and the effectiveness of the safety stock cannot be monitored.

[0039] Based on the above technical problems, an embodiment of the present application provides a nuclear power spare parts inventory management method. After determining the spare parts type of nuclear power spare parts, the reorder point value and the safety stock value are calculated for nuclear power spare parts that need to set a reorder point. The safety stock reserve rate is monitored based on the safety stock and the spare parts issuance quantity is restricted to more effectively obtain the actual guarantee situation of spare parts.

[0040] When setting the reorder point, the embodiments of this application calculate and set a safety stock level. Safety stock is an inventory reserve set to mitigate uncertainty. The reorder point increases the demand for parts during the initial procurement period based on the safety stock level to meet certain planned or anticipated sudden demands. By setting a reasonable safety stock level and designing appropriate safety stock monitoring principles, safety stock can be minimized and the availability of spare parts can be improved during critical demand periods.

[0041] The specific implementation process of the nuclear power spare parts inventory management method is described below through an embodiment.

[0042] See Figure 1 , Figure 1 The present invention provides a flowchart of a method for managing the inventory of nuclear power spare parts. Figure 1 As shown, the method may include the following steps:

[0043] S101: Determine the inventory model type corresponding to the nuclear power spare parts based on the attribute characteristics of the nuclear power spare parts.

[0044] In some embodiments, the attributes of nuclear power spare parts (hereinafter referred to as spare parts) may include frequency of use, value, volatility, and importance. Different types of spare parts require different inventory parameters. For example, high-importance spare parts are primarily focused on ensuring on-site supply, frequently used spare parts are primarily focused on reducing procurement fragmentation, and infrequent and unimportant spare parts can be used to reduce inventory levels. Therefore, the corresponding inventory model type can be determined based on the attributes of the spare parts.

[0045] For example, inventory model types are set based on spare part attributes and the inventory requirements required in actual application scenarios. Different inventory model types correspond to different inventory parameters to ensure a balance between spare part out-of-stock risk, inventory levels, and procurement concentration. The criteria for distinguishing spare part attributes can be configured through the backend. By reading the configured values of each spare part attribute, the inventory model type to which the spare part belongs is comprehensively determined.

[0046] Exemplarily, the configuration values of various attribute characteristics of spare parts may include the following configuration methods. Spare parts may be configured as high-turnover spare parts, low-turnover spare parts, and unused spare parts based on the frequency of use. Among them, high-turnover spare parts may refer to spare parts that have been used for 3 or more years in the past 5 years or have been used for 2 or more years in the past 3 years; low-turnover spare parts may refer to spare parts that have been used in the past 5 years but do not fall within the scope of high-turnover spare parts; unused spare parts may refer to spare parts that have not been used in the past 5 years. Based on the value, spare parts may be configured as high-value spare parts and low-value spare parts. Among them, high-value spare parts may be spare parts whose purchase unit price exceeds a certain price (such as RMB 10,000); low-value spare parts may be spare parts that are not within the scope of high-value spare parts. Spare parts can be configured based on the size of the fluctuation to be used, with parts with large fluctuations or parts with small fluctuations. The fluctuation coefficient is the standard deviation of the historical spare parts data divided by the average. Generally, if the fluctuation coefficient is greater than 0.5, the spare parts are with large fluctuations; otherwise, the spare parts are with small fluctuations. Spare parts can be configured based on their importance to be important or non-important. CCM and H-level spare parts can be important, while M-level and L-level spare parts can be non-important. By setting corresponding configuration values for each type of attribute feature classification, the attribute features of spare parts can be classified in multiple dimensions to meet the needs of different actual scenarios.

[0047] In some embodiments, based on the attribute characteristics of nuclear power spare parts, the inventory model type corresponding to the nuclear power spare parts is determined, including: based on the attribute characteristics of the nuclear power spare parts, determining the spare parts type corresponding to the nuclear power spare parts; based on the spare parts type, determining the inventory model type corresponding to the nuclear power spare parts.

[0048] For example, according to the attribute characteristics of each dimension of spare parts, spare parts can be divided into different spare parts types; Figure 2 As shown in the figure, based on the frequency of use, value, volatility, and importance of spare parts, spare parts are divided into spare part types T1 to T14, a total of 14 spare part types; different spare part types correspond to different inventory model types, such as Model H1, Model H2, Model L1 to Model L5, a total of six inventory model types.

[0049] When determining the inventory model type corresponding to a spare part type, adaptation can also be performed based on actual application scenarios. For example, spare part types T10 (low-turnover, high-value, non-critical spare parts) and T12 (low-turnover, low-value, non-critical spare parts) should belong to inventory model type L3 (PD+EX, no minimum inventory setting). However, due to incomplete spare part classification and identification work at some nuclear power plants (e.g., spare parts that do not have a criticality level), according to the current classification principle, spare parts that do not belong to CCM or H levels are classified as non-critical spare parts. Unclassified spare parts may include critical spare parts that have not been effectively identified. Therefore, the system will use both Model L2 and Model L3 inventory model types to calculate T10 and T12 spare parts. In actual application scenarios, users can choose based on their actual needs.

[0050] For example, for spare parts without a receipt record, usually only important spare parts need to set a minimum inventory. The current system will conduct a comprehensive evaluation based on dimensions such as the importance of such spare parts, the number of installation and usage function locations, and unit price, and calculate the minimum inventory value of the spare parts (when the minimum inventory value is 0, it is the PD+EX type). Users can then select the inventory model type and its corresponding calculation logic corresponding to the spare part type T14 according to actual application needs.

[0051] For example, the corresponding inventory model types and their operation logic for nuclear power spare parts are shown in Table 1. The difference between VB and ZB types of spare parts is that the conditions for triggering purchase requisitions for VB types are only related to the inventory quantity, the regular order quantity, and the reorder point, while the conditions for triggering purchase requisitions for ZB types are related to the inventory quantity, the regular order quantity, the reorder point, and the reserved quantity. The VB type can be used when triggering purchase requisitions based on spare part reservations is not required. The system typically uses the VB type for low-value, frequently used, and low-volatility spare parts such as chemicals and consumables. Users can also adjust the inventory model type to the VB type based on actual application needs.

[0052]

[0053] Table 1

[0054] For example, different inventory model types are correspondingly set with different inventory parameters, as shown in Table 1. Inventory parameters may include inventory quantity, regular order quantity, reserved quantity, reorder point, maximum inventory, fixed batch, conditions for triggering purchase application, and quantity for triggering purchase. For different inventory model types, the inventory parameters that need to be set and the calculation logic of each inventory parameter are also different. Among them, if each inventory parameter corresponds to NA, it does not need to be set.

[0055] S102: Determine target nuclear power spare parts for which reorder points need to be set based on inventory parameters corresponding to the inventory model type.

[0056] In some embodiments, nuclear power spare parts requiring a reorder point are determined based on the inventory model types corresponding to the spare part types and the inventory parameters contained in the inventory model types. As shown in Table 1, all inventory model types except the PD+EX inventory model type require corresponding reorder point values to be set. The target nuclear power spare part is the spare part for which a reorder point is required based on the corresponding inventory parameters.

[0057] S103: Based on the target nuclear power spare parts' procurement and purchase parameters, the corresponding reorder point and safety stock are calculated. The inventory parameters include the reorder point; the safety stock is a subdivision of the reorder point and is used to monitor the safety stock reserve ratio of nuclear power spare parts and limit the procurement quantity of nuclear power spare parts.

[0058] In some embodiments, after determining the inventory model type to which the spare part belongs based on the attribute characteristics of the spare part, the spare part for which the reorder point needs to be calculated is determined based on the inventory parameters of the inventory model type; for the spare part, the operation logic corresponding to the inventory model type is used to calculate the reorder point and safety stock of the spare part.

[0059] Among them, the safety stock is the inventory reserve set up to prevent uncertain factors, and the reorder point is to increase the demand in the early stage of procurement on the basis of the safety stock to meet certain planned demand or predictable sudden demand.

[0060] For example, after determining the inventory model type to which the spare part belongs, the reorder point and safety stock are calculated based on the spare part's requisition parameters and purchase parameters. For the spare parts in Table 1 that require a reorder point, the safety stock value is refined based on the reorder point value. Figure 3The relationship between the reorder point and safety stock is shown in the figure. The reorder point can be the sum of the safety stock and the spare parts quantity issued during the procurement cycle. Safety stock s can be further divided into safety stock s1 and safety stock s2, where s1 is the minimum single replacement quantity for spare parts. Safety stock s1 can be less than, equal to, or greater than safety stock s. When safety stock s1 is less than the calculated safety stock s, the final safety stock value is determined to be the calculated safety stock s. When safety stock s1 is greater than the calculated safety stock s, safety stock s1 is used as the final safety stock value.

[0061] In some embodiments, when calculating the reorder point and safety stock of spare parts, the calculation is performed separately based on the three categories of spare parts: high-turnover spare parts, low-turnover spare parts, and unused spare parts.

[0062] The first category: high turnover spare parts

[0063] In some embodiments, the collection parameters include the minimum single replacement quantity, the availability service level value, and the average annual collection quantity, and the procurement parameters include the unit price correction value and the procurement cycle.

[0064] When the spare parts type of the target nuclear power spare parts is a high-turnover spare part, the collection quantity within the procurement cycle is calculated based on the average annual collection quantity and procurement cycle of the target nuclear power spare parts; the safety stock quantity corresponding to the target nuclear power spare parts is determined based on the minimum single replacement quantity of the target nuclear power spare parts, the availability service level value, the unit price correction value, the average annual collection quantity and the procurement cycle; the sum of the collection quantity within the procurement cycle and the safety stock quantity is used as the reorder point.

[0065] Exemplarily, the minimum single replacement quantity is the number of spare parts that can be replaced at the installation site at one time; the availability rate service level value is the level value of the availability rate corresponding to this type of spare parts, which can be determined based on historical issuance and availability; the unit price correction value is determined based on the maximum correction value, average correction value, minimum correction value of the spare parts unit price and the size of the spare parts unit price; wherein, the maximum correction value, average correction value and minimum correction value of the spare parts unit price are known set values; for example, the maximum correction value can be 2.2, the average correction value can be 1, and the minimum correction value can be 0.45.

[0066] For example, the quantity used within the procurement cycle is calculated by calculating the ratio of the procurement cycle to the total number of days in a year, and multiplying this ratio by the average annual quantity used. Based on the historical quantity used for spare parts, the standard deviation of the average annual quantity used for spare parts is calculated. The safety stock level is calculated based on the standard deviation of the average annual quantity used, the unit price correction value, the availability service level value, and the square root of the ratio of the procurement cycle to the total number of days in a year. For example, the calculated safety stock level is the product of the standard deviation of the quantity used for spare parts, the unit price correction value, the availability service level value, and the square root of the ratio of the procurement cycle to the total number of days in a year.

[0067] Accordingly, if the calculated safety stock is greater than the minimum single replacement quantity for spare parts, the calculated safety stock is used as the final safety stock setting. If the calculated safety stock is less than the minimum single replacement quantity, the minimum single replacement quantity is used as the final safety stock setting. The sum of the final safety stock and the quantity used during the procurement cycle is used as the reorder point.

[0068] For example, the setting values of the reorder point and safety stock can be calculated by the following formulas (1) and (2):

[0069]

[0070]

[0071] Among them, r is the reorder point; g1 is the average annual usage of spare parts; t is the purchase cycle of spare parts; s is the safety stock; s1 is the minimum single replacement quantity of the spare part (such as Figure 3 The safety stock s1 shown in , for example, a pressure gauge spare part is installed on site as a whole, and the minimum number of replacements per time is 1. A gasket spare part is installed on a valve, and 4 gaskets need to be replaced at the same time during disassembly and maintenance, so the minimum number of replacements per time for this gasket is 4. z1 is the service level value of the availability rate, g2 is the standard deviation of the average annual use of spare parts, and α is the price correction coefficient based on the unit price of the spare parts. max() is the function that takes the largest value, that is, between s1 and Select the larger value between and assign it as the safety stock s.

[0072] Exemplarily, the unit price correction coefficient is calculated based on formula (3):

[0073]

[0074] Among them, δ1 is the maximum correction value of the spare part unit price, which can be set to 2.2; δ2 is the average correction value of the spare part unit price, which can be set to 1; δ3 is the minimum correction value of the spare part unit price, which can be set to 0.45; p is the purchase unit price of the spare part; the spare part can be an important spare part.

[0075] In some embodiments, after obtaining the value r of the reorder point of the spare part, it can also be modified based on the life of the spare part. The calculation process is shown in formula (4):

[0076]

[0077] Where g(x) is the rounding up of the x value, t1 is the spare part lifespan, and g1 is the average annual usage. If the calculated reorder point is greater than 0.7 times the usage within the spare part lifespan, it is corrected to 0.7 times the usage within the spare part lifespan.

[0078] The second category: low turnover spare parts

[0079] In some embodiments, for spare parts with low turnover and requiring a reorder point, the reorder point and safety stock of the spare parts are calculated using a probability distribution-based approach.

[0080] When the target nuclear power spare parts are low-turnover spare parts, the demand distribution function corresponding to the target nuclear power spare parts is determined based on the procurement parameters of the target nuclear power spare parts; based on the demand distribution function and the procurement parameters, the reorder point and safety stock quantity corresponding to the target nuclear power spare parts are calculated.

[0081] Exemplarily, the requisition parameters may include the historical requisition quantity of spare parts, and the demand characteristics of the spare parts are determined based on the historical requisition quantity. Then, a probability distribution that satisfies the demand characteristics is assumed, and parameter estimation and hypothesis testing are performed on the probability distribution. After the test is passed, the probability distribution that the target nuclear power spare parts meet is determined, and the demand distribution function corresponding to the probability distribution is obtained; based on substituting the procurement parameters into the demand distribution function, the reorder point and safety stock corresponding to the target nuclear power spare parts are calculated.

[0082] Among them, Figure 4 The flowchart shown uses Model L1, a spare parts inventory model, as an example. After determining a candidate probability distribution based on the spare parts' procurement parameters, a hypothesis test can use the KS test to calculate the test value corresponding to the candidate probability distribution. If the test value is within a preset threshold, the demand distribution function corresponding to the probability distribution is determined. The reorder point is then calculated based on this demand distribution function and output. If the test value is not within the preset threshold, other methods can be used to calculate the reorder point, such as using the maximum historical procurement quantity or quantiles based on historical procurement quantities to determine the reorder point and safety stock setting values.

[0083] The following describes the process of determining the demand distribution function based on the usage parameters.

[0084] In some embodiments, the usage parameter includes a historical usage amount, and the preset threshold is set based on the historical usage amount and a significance level, where the significance level indicates a probability of falsely rejecting the reference distribution function.

[0085] Based on the historical usage of target nuclear power spare parts, candidate probability distributions corresponding to the target nuclear power spare parts are set; non-parametric tests are performed on the candidate probability distributions, and test values of the candidate probability distributions relative to multiple reference distribution functions are calculated; when at least one test value is less than or equal to a preset threshold, the reference distribution function with the smallest test value is used as the demand distribution function.

[0086] For example, the historical usage volume can be the average annual usage volume in the corresponding spare part history records. Based on the sample data of the historical usage volume, a candidate probability distribution is set. A distribution function library is established, which includes multiple reference distribution functions, such as Poisson, binomial, normal, gamma, and Weibull. A nonparametric test is used to test the test value of the candidate probability distribution against the reference distribution function.

[0087] The non-parametric test method may be a distribution fitting test method, which compares the fit between the candidate probability distribution corresponding to the sample data of the historical usage amount and the reference distribution function. If the test value corresponding to the fit is within a preset threshold range, the reference distribution function that best matches the historical usage amount is determined. The test value is obtained by calculating the difference between the maximum absolute value of the probability distribution function corresponding to the candidate probability distribution and the reference distribution function.

[0088] Exemplarily, the preset threshold can be set based on the sample data volume and significance level (usually 0.05) corresponding to the historical usage volume. When at least one test value is less than or equal to the preset threshold, the reference distribution function corresponding to the minimum test value is used as the demand distribution function. For example, the first test value of the candidate probability distribution relative to the Poisson distribution function is within the preset threshold, and the second test value of the candidate probability distribution relative to the binomial distribution function is within the preset threshold. Then, the first test value and the second test value are compared; if the first test value is less than the second test value, the Poisson distribution function in the distribution function library is determined to be the demand distribution function corresponding to the spare part.

[0089] The following further introduces the implementation process of calculating the reorder point and safety stock of spare parts based on the demand distribution function and procurement parameters after determining the demand distribution function.

[0090] In some embodiments, the procurement parameters include the average annual procurement quantity, the number of installations, the average annual failure probability, and the average annual procurement standard deviation. The procurement parameters include the procurement cycle. The following describes the corresponding reorder points and safety stock levels for spare parts when the demand function is each reference distribution function in the distribution function library.

[0091] When the demand distribution function is a Poisson distribution function, the inventory reserve that meets the preset availability rate is calculated based on the average annual usage and procurement cycle of the target nuclear power spare parts through the Poisson distribution function.

[0092] For example, when the demand distribution function is a Poisson distribution function, the inventory reserve corresponding to the spare part is iteratively calculated based on the expression of the Poisson distribution function; the inventory reserve is accumulated starting from 0 and adding 1 each time until the result of the iterative calculation based on the expression is greater than or equal to the preset stock availability rate, thereby obtaining the iterative calculation result of the inventory reserve. For example, the inventory reserve is calculated using the following formula (5):

[0093]

[0094] Among them, g1 is the average annual usage quantity, t is the spare parts procurement cycle, z2 is the preset availability rate, e is a natural constant value, k is the inventory reserve, and r is the reorder point. The inventory reserve k is iteratively solved, that is, k is accumulated from 0 (increased by 1 each time) until the calculated availability rate is greater than or equal to the preset availability rate. The inventory reserve value that meets the preset availability rate is used as the calculation result and assigned to the reorder point r.

[0095] When the demand distribution function is a binomial distribution function, the inventory reserve that meets the preset availability rate is calculated based on the installation quantity, average annual failure probability, average annual usage, and procurement cycle of the target nuclear power spare parts through the binomial distribution function.

[0096] For example, when the demand distribution function is a binomial distribution function, the inventory reserve corresponding to the spare part is iteratively calculated based on the expression of the binomial distribution function; the inventory reserve is accumulated starting from 0 and adding 1 each time until the result of the iterative calculation based on the expression is greater than or equal to the preset stock availability rate, thereby obtaining the iterative calculation result of the inventory reserve. For example, the inventory reserve is calculated using the following formula (6):

[0097]

[0098] Where m is the number of spare parts installed, m! is the factorial of m, is the average annual failure probability of the spare part, g1 is the average annual usage, t is the spare part procurement cycle, and z2 is the preset availability rate. The inventory reserve k is iteratively solved, that is, k is accumulated from 0 (increased by 1 each time) until the calculated availability rate is greater than or equal to the preset availability rate. The inventory reserve value that meets the preset availability rate is used as the calculation result and assigned to the reorder point r.

[0099] When the demand distribution function is a normal distribution function, the inventory reserve required to meet the preset availability rate is calculated based on the average annual usage, the average annual usage standard deviation, and the procurement cycle using the normal distribution function.

[0100] For example, when the demand distribution function is a normal distribution function, the inventory reserve corresponding to the spare part is iteratively calculated based on the expression of the normal distribution function; the inventory reserve is accumulated starting from 0 and adding 1 each time until the result of the iterative calculation based on the expression is greater than or equal to the preset availability rate, thereby obtaining the iterative calculation result of the inventory reserve. For example, the inventory reserve is calculated using the following formula (7):

[0101]

[0102] Among them, g1 is the average annual collection quantity, g2 is the average annual collection standard deviation, t is the spare parts procurement cycle, and z2 is the preset availability rate. The inventory reserve k is iteratively solved, that is, k is accumulated from 0 (increased by 1 each time) until the calculated availability rate is greater than or equal to the preset availability rate. The value of the inventory reserve that meets the preset availability rate is used as the calculation result and assigned to the reorder point r.

[0103] When the demand distribution function is a gamma distribution function, the inventory reserve quantity that meets the preset availability rate is calculated based on the average annual collection quantity, the average annual collection standard deviation, and the procurement cycle through the gamma distribution function.

[0104] For example, when the demand distribution function is a gamma distribution function, the inventory reserve corresponding to the spare part is iteratively calculated based on the expression of the gamma distribution function; the inventory reserve is accumulated starting from 0 and adding 1 each time until the result of the iterative calculation based on the expression is greater than or equal to the preset availability rate, thereby obtaining the iterative calculation result of the inventory reserve. For example, the inventory reserve is calculated using the following formula (8):

[0105]

[0106] Among them, g1 is the average annual collection quantity; g2 is the average annual collection standard deviation; t is the spare parts procurement cycle; Γ(x) is the gamma function, as shown in formula (9); z2 is the set value of the stock availability rate; by iteratively solving the reserve inventory k, that is, k is accumulated from 0 (increased by 1 each time) until the calculated stock availability value is greater than or equal to the set stock availability value, the value of the inventory reserve that meets the preset stock availability rate is used as the calculation result and assigned to the reorder point r.

[0107]

[0108] Accordingly, the inventory reserve is calculated based on the above-mentioned demand distribution functions, and the minimum value of the inventory reserve that meets the preset availability rate is used as the reorder point corresponding to the target nuclear power spare parts; the safety stock is determined based on the reorder point and the single minimum replacement quantity of nuclear power spare parts.

[0109] In some embodiments, based on the same principles as for high-turnover spare parts, after obtaining the reorder point for a spare part, the reorder point is revised. For example, based on the target nuclear power spare part's lifespan and average annual usage, the reorder point is revised to obtain a revised reorder point value. Accordingly, after obtaining the revised reorder point value, the corresponding safety stock level for the spare part is determined based on the revised reorder point and the minimum single replacement quantity for the nuclear power spare part.

[0110] For example, after the reorder point r is corrected based on formula (4), the safety stock value is calculated based on the reorder point, and the calculation method is shown in formula (10), that is, the value of the safety stock s is the larger value between the single minimum replacement quantity s1 and r-1; in addition, if the relationship s1>r-1 is satisfied, the reorder point r is corrected based on the single minimum replacement quantity s1, and the calculation method is shown in formula (11):

[0111] s=max(s1,r-1) (10)

[0112] r=s1+1 (11)

[0113] The third category: no spare parts

[0114] In some embodiments, when the spare part type of the target nuclear power spare part is an unissued spare part, the single minimum replacement quantity of the target nuclear power spare part is used as the safety stock; the safety stock is increased by one to obtain the reorder point.

[0115] For example, when there is no spare part available and a reorder point needs to be set, the corresponding safety stock is set to the minimum single replacement quantity s1, as shown in formula (12); the reorder point r is the safety stock s plus 1, as shown in formula (13):

[0116] s=s1 (12)

[0117] r=s+1 (13)

[0118] The following further introduces the implementation process of monitoring the safety stock reserve rate of nuclear power spare parts based on the set safety stock quantity.

[0119] In some embodiments, in order to ensure stable operation of the unit, a reserve inventory needs to be set. Currently, some nuclear power plants have set an assessment indicator for the spare parts reserve rate. The calculation method of the spare parts reserve rate corresponding to the current spare parts is shown in formulas (14) and (15):

[0120]

[0121] In formula (14), p i is the spare parts reserve rate of spare part i, ST iis the current inventory quantity of spare part i. When the inventory quantity of the spare part is greater than 0, its spare part reserve rate is 100%; when the inventory quantity of the spare part is equal to 0, its spare part reserve rate is 0%.

[0122] Correspondingly, p is the average availability rate of spare parts for a given batch (n items). Generally, if a spare part does not have a reorder point, it means that the spare part does not need to be kept in regular inventory, and therefore such spare parts are not included in the spare parts reserve rate statistics.

[0123] In order to improve the security of the spare parts reserve rate, a safety stock of spare parts is set for each spare part with a reorder point. Based on the safety stock, the above spare parts reserve rate is adjusted to the safety stock reserve rate. Based on the current inventory and safety stock of the target nuclear power spare parts, the safety stock reserve rate of each target nuclear power spare part is determined. Based on the safety stock reserve rate, the average availability rate of the target batch spare parts is calculated. The average availability rate of the target batch spare parts is used to monitor the overall inventory situation of the nuclear power spare parts in the target batch.

[0124] For example, the safety stock reserve ratio of spare parts is calculated by the following formula (16):

[0125]

[0126] In formula (16), p i is the safety stock reserve ratio of spare part i, ST i is the current inventory of spare part i, s is the safety stock of spare part i. When the current inventory of the spare part is greater than or equal to the safety stock s, its safety stock reserve rate is 100%; when the current inventory of the spare part is less than the safety stock s, its safety stock reserve rate is the ratio of the current inventory to the safety stock.

[0127] Accordingly, based on the safety stock reserve rate of a single spare part, the average availability rate of a specified batch of spare parts can be calculated, and the calculation method is shown in formula (15).

[0128] The following further describes the implementation process of managing the use of nuclear power spare parts based on the set safety stock quantity through an embodiment.

[0129] In some embodiments, nuclear power spare parts are reserved through work orders and then issued and installed on-site during maintenance activities. Nuclear power work orders come in multiple types, including general maintenance orders, corrective action process orders, preventive maintenance orders, supervisory testing orders, and engineering modification orders. Different work orders also vary in importance. For general maintenance orders, maintenance personnel prepare and classify them based on the type and severity of defects found on-site. For example, defect types can include equipment defects, structural defects, and equipment corrosion; and defect severity can include functional failure, severe defects, moderate defects, and minor defects. For preventive maintenance orders, such as some non-critical overhauls, if spare parts are unavailable, the order can be canceled or postponed, and no maintenance activities will be performed during this overhaul. However, some critical overhauls, particularly those involving nuclear safety-related equipment, require scheduled maintenance and cannot be canceled or postponed; they must be executed as planned.

[0130] The same spare part may be requested by different types of work orders, each with different importance. For non-critical work orders, the tolerance for delayed execution (due to a shortage of spare parts) is higher; for critical work orders, the tolerance for delayed execution (due to a shortage of spare parts) is lower. Typically, spare part request demand is highly random. While it's known that a spare part will be reserved for future work order requests, it's difficult to effectively predict the type of work order that will request it.

[0131] To improve the availability of spare parts for important work orders, it is necessary to implement restricted spare parts inventory management. When the spare parts inventory quantity falls below the safety stock, it is necessary to determine whether the spare parts demand can be met if there are work order reservations based on the importance of the work order and the expected availability of spare parts.

[0132] In some embodiments, the available quantity of work orders is regulated based on the relationship between the actual inventory and the safety inventory, the work order type corresponding to the nuclear power spare parts, the work order reserved quantity corresponding to the work order, the minimum replacement quantity per time, and the expected availability rate and availability rate threshold corresponding to the work order type.

[0133] For example, based on the relationship between the actual inventory and the safety stock, the work order type of the nuclear power spare parts work order, the work order reserved quantity corresponding to the work order, the minimum single replacement quantity, and the expected availability rate and availability rate threshold corresponding to the work order type, the available quantity of the work order is regulated, including:

[0134] Calculate the first difference between the actual inventory and the safety stock, and the second difference between the actual inventory and the minimum single replacement quantity; when the actual inventory is greater than the safety stock, determine the available quantity to be the minimum of the work order reserved quantity and the first difference; when the minimum single replacement quantity is less than the actual inventory, the actual inventory is less than or equal to the safety stock, and the expected availability is greater than or equal to the availability threshold, determine the available quantity to be the minimum of the work order reserved quantity and the second difference; when the minimum single replacement quantity is less than the actual inventory, the actual inventory is less than or equal to the safety stock, and the expected availability is less than the availability threshold, determine the available quantity to be zero; wherein the availability threshold is set based on the work order type; the expected availability is set based on the probability distribution of the historical availability of nuclear power spare parts, or based on the probability distribution of all nuclear power spare parts under the manufacturer's name of the spare parts category to which the nuclear power spare parts belong.

[0135] For example, Figure 5 As shown in the figure, assuming that the spare parts will be replenished at the end of the 12th month (the purchased spare parts arrive at the power plant warehouse to replenish the inventory), the safety stock of the spare parts s is 10, and the minimum single replacement quantity s1 is 1. When the actual inventory of the spare parts ( Figure 5 When the inventory quantity shown in Figure 5 From January to March as shown in ), there is no restriction on the use of spare parts to meet the use requirements of all work orders. As shown in formula (17), the available quantity of the work order is l, which is equal to the minimum value between the work order reserved quantity R and ST-s (actual inventory minus safety stock).

[0136] l=min(R,ST-s) (17)

[0137] Accordingly, when the actual inventory of spare parts (such as Figure 5 When the actual inventory of spare parts is greater than the minimum single replacement quantity s1 (such as Figure 5 When the safety stock s1 shown in Figure 5 ), then based on the work order type and the expected stock availability rate at the current moment, it is determined whether the demand of the current work order can be met; as shown in formula (18), different stock availability thresholds q are set for different work order types. k , when the expected availability rate q is greater than or equal to the availability rate threshold q of this type of work order k , the demand for the work order is allowed, and the available quantity of the work order is l, which is equal to the minimum value between the work order reserved quantity R and ST-s1 (actual inventory minus the minimum single replacement quantity); when the expected availability rate q is less than the availability rate threshold q of this type of work order k, the collection requirements of the work order cannot be met, then the corresponding available quantity of the work order is 0.

[0138]

[0139] like Figure 5 As shown, in the 4th, 6th, 8th and 9th months, the demand for the collection of work orders is met based on the expected availability rate and the corresponding work order type. In the 5th and 7th months, the demand for the collection of work orders is not met based on the expected availability rate and the corresponding work order type.

[0140] Accordingly, if Figure 5 As shown, after the 10th month, since the actual inventory is less than or equal to the minimum single replacement quantity s1, at this time, on the basis of satisfying the work order type (usually limited to the most important work order type) and the expected availability rate, it is necessary to manually judge whether the remaining inventory (minimum single replacement quantity s1) can be used for this work order demand. Based on this judgment principle, the work order collection demand for the 11th month is met, while the work order collection demand for the 10th month is not met.

[0141] Exemplarily, the work order types include the first type, the second type and the third type based on importance, and the availability rate threshold includes the first threshold corresponding to the first type of work order, the second threshold corresponding to the second type of work order and the third threshold corresponding to the third type of work order; the importance of the first type of work order is greater than the importance of the second type of work order, and the importance of the second type of work order is greater than the importance of the third type of work order; the first threshold is smaller than the second threshold, and the second threshold is smaller than the third threshold.

[0142] The following further describes the implementation process of setting the expected stock availability rate through an embodiment. When the demand characteristics of spare parts meet a certain probability density, by establishing a corresponding demand distribution function, the expected stock availability rate of spare parts can be calculated when the corresponding inventory quantity is reserved. Figure 6 As shown, the process of calculating the expected availability rate may include the following steps:

[0143] S601 : Determine a first probability distribution corresponding to the nuclear power spare parts based on a first historical usage quantity of the nuclear power spare parts.

[0144] S602: Calculate a test value of the first probability distribution relative to a reference distribution function.

[0145] S603: Determine whether the test value is less than or equal to a preset threshold. If so, execute S604; if not, execute S605. The preset threshold is set based on the first historical usage amount and the significance level.

[0146] S604: When the test value is less than or equal to a preset threshold, determine a first probability distribution with a minimum test value as a demand distribution function for nuclear power spare parts.

[0147] For example, based on the first historical usage quantity of spare parts, a method such as the KS test (Kolmogorov-Smirnvotest) is used to determine whether the first historical usage quantity conforms to a corresponding probability distribution, thereby selecting an appropriate demand distribution function. For each reference distribution function in the distribution function library, a KS test value is calculated using the KS test method. If the KS test value is within a preset threshold, the reference distribution function corresponding to the optimal KS test value is selected and used as the spare parts demand distribution function.

[0148] S605 , when the inspection value is greater than the preset threshold, based on the spare parts category of the nuclear power spare parts, obtain a second historical usage quantity of the nuclear power spare parts of the manufacturer to which the spare parts category belongs.

[0149] S606: Determine a second probability distribution based on the second historical usage amount, and calculate a test probability value of the second probability distribution relative to the reference distribution function.

[0150] S607: When the test probability value is greater than the significance level, determine the second probability distribution with the largest test probability value as the demand distribution function of nuclear power spare parts.

[0151] For example, if the KS test values corresponding to the reference distribution functions in the distribution function library are not within the preset threshold, the spare parts category and manufacturer of the spare parts are selected, and the demand distribution function of all spare parts under the spare parts category and manufacturer is calculated.

[0152] Among them, in actual application scenarios, the fineness of spare parts attribute classification can be selected according to the number of codes of nuclear power plants; if the types of spare parts classification are increased, the number of spare parts under each spare parts category will be reduced; while ensuring that there are enough spare parts codes for each spare parts category, the fineness of spare parts attribute classification can be selected based on the following examples: Figure 7 The spare parts classification principles shown above increase the types of spare parts classification, that is, increase the spare parts categories.

[0153] For example, a spare part belongs to the 060203 pressure switch in the 06 instrument category, and its manufacturer is A. If the nuclear power plant uses a large number of 060203 pressure switch spare parts supplied by manufacturer A, then the second historical usage quantity corresponding to all spare parts of manufacturer A and spare part category 060203 pressure switch is directly obtained, and the KS test is applied to calculate the reference distribution function with the highest proportion of spare parts in this batch that meet the KS test requirements; if the nuclear power plant uses a small number of 060203 pressure switch spare parts supplied by manufacturer A, then the 06 instrument category spare parts supplied by manufacturer A are obtained, and the KS test is applied to calculate the reference distribution function with the highest proportion of spare parts in this batch that meet the KS test requirements.

[0154] Exemplarily, based on the spare parts classification and the second historical usage quantity of all spare parts under the manufacturer's name, the KS test method is used to calculate the degree of fit of the batch of spare parts under the "normal distribution function, Poisson distribution function, Weibull distribution function, exponential distribution function, gamma distribution function, and uniform distribution function". When the test probability value (KS test value p_value) is greater than the significance level (usually set to 0.05), the reference distribution function is accepted. When the test probability value (KS test value p_value) is less than or equal to the significance level (usually set to 0.05), the reference distribution function is rejected. If the spare part meets the test of multiple reference distribution functions, the demand function with the highest fit is selected.

[0155] For example, taking a spare part as an example, based on its corresponding second historical usage quantity, the normal distribution function, Poisson distribution function, Weibull distribution function, exponential distribution function, gamma distribution function, and uniform distribution function are used for fitting. The cumulative probability distribution of each reference distribution function is as follows: Figure 8 As shown, the KS test probability values for the normal distribution, Poisson distribution, and exponential distribution meet the 0.05 significance level requirement, while the KS test probability values for the Weibull distribution, gamma distribution, and uniform distribution do not meet the 0.05 significance level requirement. Among the normal, Poisson, and exponential distributions, assuming the relative deviation distance between the normal distribution and the actual usage distribution (i.e., the distribution of the second historical usage quantity) is 1, the relative deviation distance for the Poisson distribution is 0.94, and the relative deviation distance for the exponential distribution is 1.34. This means that the Poisson distribution has the smallest relative deviation from the actual usage distribution and the highest degree of fit. Therefore, the Poisson distribution is selected as the demand distribution function for this spare part.

[0156] For example, taking the sample data of 15,000 spare parts of a nuclear power plant as an example, the historical usage of this batch of spare parts in the past five years is counted, and the statistics are summarized according to the usage of spare parts every six months. For each spare part, 10 sample data can be obtained. The KS test method is used to calculate the demand distribution function with the highest spare part fitting degree.

[0157] like Figure 9 As shown in (a), for all spare parts in this batch, 49% of the spare parts cannot be fitted using any reference distribution function, and 51% of the spare parts can be fitted using a reference distribution function; among them, the number of spare parts that meet the normal distribution is the largest, accounting for 36%, followed by the Poisson distribution, accounting for 6%. Spare parts of different spare parts categories and manufacturers have different demand distribution functions, such as Figure 9 As shown in (b), for spare parts in a certain spare parts category - manufacturer name, 44% of the spare parts cannot be fitted using any reference distribution function, and 56% of the spare parts can be fitted using a reference distribution function; among them, the number of spare parts items that meet the Poisson distribution is the largest, accounting for 19%, followed by the gamma distribution, accounting for 13%.

[0158] S608: Calculate the expected availability rate based on the demand distribution function, the current inventory of nuclear power spare parts, the average annual usage quantity, and the procurement parameters.

[0159] For example, if a corresponding demand distribution function can be determined based on the first historical usage of a spare part, the expected availability rate is calculated based on this demand distribution function. If a corresponding demand distribution function cannot be determined based on the first historical usage of a spare part, the reference distribution function corresponding to all spare parts under the manufacturer's name and the spare part category to which the spare part belongs is calculated, and the reference distribution function with the highest reference distribution function percentage is used as the demand distribution function for the spare part. The expected availability rate is calculated based on the demand distribution function, the current inventory of nuclear power spare parts, the average annual usage, and procurement parameters.

[0160] The following takes the Poisson distribution function as an example to further introduce the calculation process of the expected availability rate.

[0161] In some embodiments, calculating the expected availability rate based on the demand distribution function, the current inventory of nuclear power spare parts, the average annual usage, and the procurement parameters may include:

[0162] When there is a purchase order for spare parts, the current inventory, average annual usage, and number of days from the current time to the arrival of the purchase order are substituted into the demand distribution function to obtain the expected availability rate. When there is no purchase order for spare parts, the current inventory, average annual usage, and procurement cycle of nuclear power spare parts are substituted into the demand distribution function to obtain the expected availability rate. Among them, the procurement parameters include the number of days from the current time to the arrival of the purchase order or the procurement cycle, and whether there is a purchase list or not.

[0163] For example, the expected availability rate is calculated based on the expression of the demand distribution function. For example, when the demand distribution function is a Poisson distribution function, the expected availability rate is calculated using the following formula (19):

[0164]

[0165] Where ST is the current inventory of the spare part, g1 is the average annual usage of the spare part, e is a natural constant value, and t1 is the number of days from the current time to the arrival of the purchase order. If a purchase order already exists for the spare part, the expected delivery date in the purchase order minus the current time (i.e., calculate the number of days from the current time to the agreed delivery time in the purchase order). If no purchase order exists for the spare part, the spare part procurement cycle t is assigned to t1.

[0166] Taking a spare part as an example, the relationship between its arrival time and expected availability rate under different inventory reserves is as follows: Figure 10 As shown. Figure 10 It can be obtained that when the reserve inventory quantity remains unchanged, as the time to arrival t1 decreases, the expected replacement quantity within the time to arrival will become smaller, so the expected availability rate q of spare parts will become larger. Figure 10 In the example, when 8 inventory quantities are reserved and there are still 8 months (240 days) until the arrival of the goods, the calculated expected availability rate is 59%. If there is a low-importance work order request on site (the availability threshold q3 is 70%), the expected availability rate is lower than the availability threshold (59% < 70%), and therefore the work order's demand cannot be met. As time passes, when there are still 6 months (180 days) until the arrival of the goods, the calculated expected availability rate is 85%. At this time, if there is a low-importance work order request on site (the availability threshold q3 is 70%), the expected availability rate is higher than the availability threshold (85% > 70%), and therefore the work order's demand can be met.

[0167] In some embodiments, taking the data of a spare part as an example, without applying safety stock control, the distribution of its inventory quantity, expected availability rate, and other spare parts quantity is as follows: Figure 11 The spare parts inventory quantity is related to the inventory quantity, acceptance quantity and issuance quantity of the previous month, and its calculation method is shown in formula (20):

[0168] ST t+1 =ST t +Y t -L t (20)

[0169] Among them, ST t is the inventory quantity at time t, Y t is the acceptance quantity at time t (spare parts are purchased and inspected upon arrival and included in inventory), L tis the quantity of parts to be collected at time t. The expected availability is the availability data calculated based on formula (19). The equivalent spare parts quantity is the quantity that has a work order collection demand at the simulation time, but cannot meet the reserved quantity of the work order. After the subsequent spare parts are purchased and delivered, the reserved collection demand of the work order will be met when the inventory quantity is sufficient.

[0170] exist Figure 11 In (a), there are nine work orders waiting for spare parts: three of them are of high importance, three are of medium importance, and three are of low importance. Without safety stock control, the system only determines whether work order demand can be met based on the current inventory level. If there is sufficient inventory, the work order request is met; if there is insufficient inventory, the work order request cannot be met. Therefore, in this scenario, even high-importance work orders experience a high number of waiting for spare parts.

[0171] by Figure 11 Taking the initial inventory quantity, inventory parameters (safety stock s is 6, single minimum replacement quantity s1 is 1, availability thresholds q1, q2, q3 are 0%, 40%, 70% respectively) and the requisition demand of the spare parts shown in (a) as an example, after safety stock control, the distribution of inventory quantity, expected availability rate, and spare parts quantity is as follows: Figure 11 As shown in (b) in .

[0172] For example, in the 18th month of the simulation, the expected availability rate for spare parts is 68%. At this time, there is a low-importance work order with a demand for spare parts. The current expected availability rate is lower than the availability rate threshold q3 (70%), which cannot meet the demand for this work order. As a result, one low-importance work order is waiting for spare parts (in the 22nd month, 12 spare parts have arrived. Meeting the demand for spare parts this time is equivalent to delaying the demand for spare parts by 4 months). Similarly, due to not meeting the availability rate threshold or insufficient inventory during the period, medium-importance and low-importance work orders all experience a waiting time for spare parts in months 32, 33, 34, 50, 51, 54, 83, 89, and 90.

[0173] Accordingly, by comparison Figure 11 (a) and Figure 11 (b) in the Figure 11 The number of spare parts in (b) is greater than Figure 11 (a) in the example (10 in the former and 9 in the latter), but the corresponding work order types for the two are different; Figure 11 In (b), there is no situation where the work orders with high importance have to wait for spare parts, and the work orders with medium importance have to wait for spare parts, which remains unchanged.

[0174] Table 2 shows the distribution of spare parts for various work order types before and after safety stock control. When the actual spare part inventory is less than or equal to the safety stock, intervention is made on the work order for the spare part to minimize the consumption of the safety stock. This improves the availability of spare parts for critical work order requirements.

[0175]

[0176] Table 2

[0177] In the embodiment of the present application, nuclear power spare parts are classified based on their attribute characteristics, and the inventory model type to which the nuclear power spare parts belong is determined, thereby determining the nuclear power spare parts that require setting a reorder point based on the inventory model type; for nuclear power spare parts that require setting a reorder point, the corresponding reorder point and safety stock quantity are calculated based on the corresponding collection parameters and procurement parameters of the nuclear power spare parts, and the setting values of the safety stock quantity sub-items are clearly set, thereby effectively monitoring the safety stock reserve rate based on the safety stock quantity, and at the same time limiting the collection quantity of nuclear power spare parts based on the safety stock reserve rate, thereby improving the degree of guarantee of the collection demand of important spare parts.

[0178] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0179] Corresponding to the nuclear power spare parts inventory management method provided in the above embodiment, Figure 12 A structural schematic diagram of a nuclear power spare parts inventory management device provided in an embodiment of the present application is shown. For ease of explanation, only the parts related to the embodiment of the present application are shown.

[0180] Reference Figure 12 , the device comprises:

[0181] A classification unit, configured to determine an inventory model type corresponding to a nuclear power spare part based on attribute characteristics of the nuclear power spare part;

[0182] An identification unit, configured to determine, based on inventory parameters corresponding to the inventory model type, target nuclear power spare parts for which a reorder point needs to be set;

[0183] A calculation unit is used to calculate the reorder point and safety stock corresponding to the target nuclear power spare parts based on the collection parameters and procurement parameters of the target nuclear power spare parts; wherein, the inventory parameters include the reorder point; the safety stock is a subdivision of the reorder point, and the safety stock is used to monitor the safety stock reserve rate of the nuclear power spare parts and limit the collection quantity of the nuclear power spare parts.

[0184] In a possible implementation, the device is also used to implement other steps in the above method embodiment.

[0185] Figure 13 A schematic diagram of the hardware structure of the electronic device 13 is shown.

[0186] like Figure 13 As shown, the electronic device 13 of this embodiment includes: at least one processor 130 ( Figure 13 Only one is shown), a memory 131, wherein the memory 131 stores a computer program 132 that can be run on the processor 130. When the processor 130 executes the computer program 132, the steps in the above method embodiment are implemented, such as Figure 1 Alternatively, when the processor 130 executes the computer program 132, the functions of the modules / units in the above-mentioned device embodiments are realized.

[0187] It should be understood that the structures illustrated in the embodiments of the present application do not constitute a specific limitation on the electronic device 13. In other embodiments of the present application, the electronic device 13 may include more or fewer components than shown, or may combine or separate certain components, or arrange the components differently. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0188] The electronic device 13 may include, but is not limited to, a processor 130 and a memory 131. Those skilled in the art will appreciate that Figure 13 It is only an example of the electronic device 13 and does not constitute a limitation of the electronic device 13. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the server may also include an input sending device, a network access device, a bus, etc.

[0189] The processor 130 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor.

[0190] Processor 130 may also include a memory for storing instructions and data. In some embodiments, the memory in processor 130 is a cache memory. This memory can store instructions or data that have just been used or are being recycled by processor 130. If processor 130 needs to use the same instruction or data again, it can directly access the memory. This avoids duplicate accesses, reduces processor 130 latency, and thus improves system efficiency.

[0191] In some embodiments, the memory 131 may be an internal storage unit of the electronic device 13, such as a hard disk or memory of the electronic device 13. The memory 131 may also be an external storage device of the electronic device 13, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the electronic device 13. Furthermore, the memory 131 may include both an internal storage unit of the electronic device 13 and an external storage device. The memory 131 is used to store an operating system, application programs, a boot loader, data, and other programs, such as program code of a computer program. The memory 131 may also be used to temporarily store data that has been sent or is about to be sent.

[0192] In addition, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0193] It should be noted that the structure of the above-mentioned electronic device is only illustrative, and based on different application scenarios, it may also include other physical structures, and the physical structure of the electronic device is not limited here.

[0194] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0195] An embodiment of the present application further provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it can implement the steps in the above-mentioned various method embodiments.

[0196] An embodiment of the present application provides a computer program product. When the computer program product runs on a server, the server can implement the steps in the above-mentioned method embodiments when executing the computer program product.

[0197] If the integrated module / unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the process in the above-mentioned embodiment method, and can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form, etc. Computer-readable media may include: any entity or device that can carry computer program code, recording medium, U disk, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium, etc.

[0198] The electronic device, computer storage medium, and computer program product provided in the above-mentioned embodiments of the present application are all used to execute the methods provided above. Therefore, the beneficial effects that can be achieved can refer to the beneficial effects corresponding to the methods provided above, and will not be repeated here.

[0199] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0200] It should be understood that the above is only to help those skilled in the art better understand the embodiments of the present application, and is not intended to limit the scope of the embodiments of the present application. Based on the above examples given, those skilled in the art can obviously make various equivalent modifications or changes. For example, certain steps in each embodiment of the above detection method may be unnecessary, or certain new steps may be added. Or a combination of any two or any multiple embodiments described above. Such modifications, changes, or combined solutions also fall within the scope of the embodiments of the present application.

[0201] It should also be understood that the division of the modes, situations, categories and embodiments in the embodiments of the present application is only for the convenience of description and should not constitute a special limitation. The features of various modes, categories, situations and embodiments can be combined without contradiction.

[0202] It should also be understood that in the various embodiments of the present application, unless otherwise specified or there is a logical conflict, the terms and / or descriptions between different embodiments are consistent and can be referenced to each other, and the technical features in different embodiments can be combined to form new embodiments according to their internal logical relationships.

[0203] Those skilled in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0204] In the embodiments provided in this application, it should be understood that the disclosed devices / network equipment and methods can be implemented in other ways. For example, the device / network equipment embodiments described above are merely illustrative. For example, the division of the modules or units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0205] The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of these units may be selected to achieve the purpose of this embodiment according to actual needs.

[0206] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

[0207] Finally, it should be noted that the above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A method for managing nuclear power spare parts inventory, characterized in that: The method comprises: Determining an inventory model type corresponding to the nuclear power spare parts based on attribute characteristics of the nuclear power spare parts; Determining target nuclear power spare parts requiring reorder points based on inventory parameters corresponding to the inventory model type; Calculating the reorder point and safety stock quantity corresponding to the target nuclear power spare parts based on the requisition parameters and procurement parameters of the target nuclear power spare parts; Among them, the inventory parameters include the reorder point; the safety stock is a subdivision of the reorder point, and the safety stock is used to monitor the safety stock reserve rate of the nuclear power spare parts and limit the amount of the nuclear power spare parts issued.

2. The method according to claim 1, characterized in that The determining, based on the attribute characteristics of the nuclear power spare parts, the inventory model type corresponding to the nuclear power spare parts includes: Determining a spare part type corresponding to the nuclear power spare part based on the attribute characteristics of the nuclear power spare part; Based on the spare part type, the inventory model type corresponding to the nuclear power spare part is determined.

3. The method according to claim 1, characterized in that The calculating the reorder point and safety stock quantity corresponding to the target nuclear power spare parts based on the requisition parameter and the purchase parameter of the target nuclear power spare parts includes: If the target nuclear power spare parts are high-turnover spare parts, the quantity used in the procurement cycle is calculated based on the average annual quantity used and the procurement cycle of the target nuclear power spare parts. Determine the safety stock amount corresponding to the target nuclear power spare part based on the minimum single replacement quantity of the target nuclear power spare part, the availability service level value, the unit price correction value, the average annual usage quantity and the procurement cycle; The sum of the quantity taken during the procurement cycle and the safety stock is used as the reorder point; Among them, the collection parameters include the minimum single replacement quantity, the availability service level value and the average annual collection quantity, and the procurement parameters include the unit price correction value and the procurement cycle.

4. The method according to claim 1, wherein The calculating the reorder point and safety stock quantity corresponding to the target nuclear power spare parts based on the requisition parameter and the purchase parameter of the target nuclear power spare parts includes: In a case where the target nuclear power spare parts are low-turnover spare parts, determining a demand distribution function corresponding to the target nuclear power spare parts based on the usage parameters of the target nuclear power spare parts; Based on the demand distribution function and the procurement parameters, the reorder point and safety stock quantity corresponding to the target nuclear power spare parts are calculated.

5. The method according to claim 4, characterized in that The determining, based on the usage parameter of the target nuclear power spare part, a demand distribution function corresponding to the target nuclear power spare part includes: Based on the historical usage of the target nuclear power spare parts, setting a candidate probability distribution corresponding to the target nuclear power spare parts; Performing a nonparametric test on the candidate probability distribution, and calculating test values of the candidate probability distribution relative to a plurality of reference distribution functions; When at least one of the test values is less than or equal to a preset threshold, the reference distribution function with the smallest test value is used as the demand distribution function; The usage parameter includes the historical usage amount, the preset threshold is set based on the historical usage amount and a significance level, and the significance level indicates the probability of falsely rejecting the reference distribution function.

6. The method according to claim 4, characterized in that The calculating, based on the demand distribution function and the procurement parameter, the reorder point and the safety stock corresponding to the target nuclear power spare parts includes: When the demand distribution function is a Poisson distribution function, based on the average annual usage and procurement cycle of the target nuclear power spare parts, the inventory reserve quantity that meets the preset availability rate is calculated using the Poisson distribution function; or When the demand distribution function is a binomial distribution function, the inventory reserve that meets the preset availability rate is calculated based on the installed quantity, average annual failure probability, average annual usage, and procurement cycle of the target nuclear power spare parts through the binomial distribution function; or When the demand distribution function is a normal distribution function, the inventory reserve quantity that satisfies the preset availability rate is calculated based on the average annual usage, the average annual usage standard deviation, and the procurement cycle through the normal distribution function; or When the demand distribution function is a gamma distribution function, the inventory reserve quantity that meets the preset availability rate is calculated based on the average annual collection quantity, the average annual collection standard deviation, and the procurement cycle through the gamma distribution function; Using the minimum value of the inventory reserve that meets the preset availability rate as the reorder point corresponding to the target nuclear power spare part; Determining the safety stock amount based on the reorder point and the single minimum replacement quantity of the nuclear power spare parts; Among them, the procurement parameters include the average annual procurement quantity, installation quantity, average annual failure probability, and average annual procurement standard deviation, and the procurement parameters include the procurement cycle.

7. The method according to any one of claims 3 to 6, characterized in that After calculating the reorder point corresponding to the target nuclear power spare parts, the method further includes: Based on the spare parts life and the average annual usage of the target nuclear power spare parts, the reorder point is corrected to obtain a corrected value of the reorder point.

8. The method according to claim 1, characterized in that After determining the target nuclear power spare parts for which a reorder point needs to be set based on the inventory parameters corresponding to the inventory model type, the method further includes: In the case where the target nuclear power spare part is a spare part that is not in use, the minimum single replacement quantity of the target nuclear power spare part is used as the safety stock; The safety stock amount is increased by one to obtain the reorder point.

9. The method according to any one of claims 1 to 8, characterized in that After calculating the reorder point and safety stock amount corresponding to the target nuclear power spare parts, the method further includes: Determining a safety stock reserve ratio of each target nuclear power spare part based on the current inventory of the target nuclear power spare part and the safety stock; Based on the safety stock reserve rate, the average availability rate of the target batch of spare parts is calculated; the average availability rate of the target batch of spare parts is used to monitor the overall inventory status of the nuclear power spare parts in the target batch.

10. The method according to any one of claims 1 to 8, characterized in that After calculating the reorder point and safety stock amount corresponding to the target nuclear power spare parts, the method further includes: Based on the relationship between the actual inventory and the safety stock, the work order type of the nuclear power spare parts corresponding to the work order, the work order reserved quantity corresponding to the work order, the minimum replacement quantity per time, and the expected availability rate and availability rate threshold corresponding to the work order type, the available quantity of the work order is regulated.

11. The method according to claim 10, characterized in that Based on the relationship between the actual inventory and the safety stock, the work order type of the nuclear power spare part corresponding to the work order, the work order reserved quantity corresponding to the work order, the minimum single replacement quantity, and the expected availability rate and availability rate threshold corresponding to the work order type, the available quantity of the work order is regulated, including: Calculating a first difference between the actual inventory and the safety stock, and a second difference between the actual inventory and the single minimum replacement quantity; When the actual inventory is greater than the safety stock, determining the available quantity to be the minimum value between the work order reserved quantity and the first difference; If the single minimum replacement quantity is less than the actual inventory, the actual inventory is less than or equal to the safety stock, and the expected stock availability is greater than or equal to the stock availability threshold, the available quantity is determined to be the minimum value between the work order reserved quantity and the second difference; When the single minimum replacement quantity is less than the actual inventory, the actual inventory is less than or equal to the safety stock, and the expected stock availability is less than the stock availability threshold, determining the available quantity to be zero; Among them, the availability rate threshold is set based on the work order type; the expected availability rate is set based on the probability distribution of the historical usage of the nuclear power spare parts, or based on the probability distribution of all nuclear power spare parts under the manufacturer's name in the spare parts category to which the nuclear power spare parts belong.

12. The method according to claim 11, characterized in that The work order types of the work order include a first type, a second type and a third type based on importance, and the availability rate threshold includes a first threshold corresponding to the first type of work order, a second threshold corresponding to the second type of work order, and a third threshold corresponding to the third type of work order; the importance of the first type of work order is greater than the importance of the second type of work order, and the importance of the second type of work order is greater than the importance of the third type of work order; the first threshold is smaller than the second threshold, and the second threshold is smaller than the third threshold.

13. The method according to claim 11, characterized in that Methods for setting the expected availability rate include: Determining a first probability distribution corresponding to the nuclear power spare parts based on a first historical usage quantity of the nuclear power spare parts, and calculating a test value of the first probability distribution relative to a reference distribution function; In the case where the test value is less than or equal to a preset threshold, determining the first probability distribution with the minimum test value as the demand distribution function of the nuclear power spare parts; or, When the inspection value is greater than the preset threshold, based on the spare parts category of the nuclear power spare parts, obtaining a second historical usage quantity of the nuclear power spare parts of the manufacturer to which the spare parts category belongs; Determining a second probability distribution based on the second historical usage amount, and calculating a test probability value of the second probability distribution relative to the reference distribution function; In the case where the test probability value is greater than the significance level, determining a second probability distribution with a maximum test probability value as the demand distribution function of the nuclear power spare parts; Calculating the expected availability rate based on the demand distribution function, the current inventory of the nuclear power spare parts, the average annual usage, and the procurement parameter; The preset threshold is set based on the first historical usage amount and the significance level.

14. The method according to claim 13, characterized in that The calculating the expected availability rate based on the demand distribution function, the current inventory of the nuclear power spare parts, the average annual usage quantity and the procurement parameter includes: In the case where a purchase order exists for the nuclear power spare parts, the current inventory quantity, the average annual usage quantity, and the number of days from the current time to the arrival of the purchase order for the nuclear power spare parts are substituted into the demand distribution function to obtain the expected availability rate; In the case where there is no purchase order for the nuclear power spare parts, substituting the current inventory, the average annual usage, and the procurement cycle of the nuclear power spare parts into the demand distribution function to obtain the expected availability rate; The purchasing parameters include the number of days from the current time to the arrival of the purchase order or the purchasing cycle, and whether there is a purchase list or not.

15. An electronic device, characterized in that: The method comprises a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the method according to any one of claims 1 to 14 is implemented.

16. A computer program product, characterized in that When the computer program product is run on a device, the device is caused to perform the method according to any one of claims 1 to 14.

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