Method for determining heat pipe reactor drum test period and calculation device

Abstract

The method for determining the heat pipe reactor rotary drum test period comprises the following steps: providing a jamming probability of a rotary drum driving mechanism of a heat pipe reactor and a common cause jamming probability of the rotary drum driving mechanism; establishing a fault tree model, and calculating the failure probability of the drum driving mechanism and the importance of the drum driving mechanism jamming basic event and the drum driving mechanism common cause jamming basic event; establishing a reference curve of the failure probability and the importance degree of the drum driving mechanism along with the change of the test period; and taking a test period corresponding to an intersection point of the two reference curves as a reference test period of the heat pipe reactor drum cycle test. According to the method, periodic test design of the drum driving mechanism can be guided in a quantitative calculation mode, and the reactor economy is optimized. The invention further provides a computing device.

Description

Technical Field

[0001] The invention belongs to the field of nuclear power, and in particular relates to a method and a calculation device for determining a drum test cycle of a heat pipe reactor. Background Art

[0002] The drum drive mechanism is a key component of the heat pipe reactor for reactor startup, power regulation and shutdown operations, and has an important impact on the safe operation of the heat pipe reactor. The drum drive mechanism mainly includes a drive motor, a reset energy storage device, etc., and its control function is achieved by controlling the rotation of the drum. In order to ensure the reliability of the drum mechanism, especially to reduce the failure probability of the shutdown function, it is necessary to carry out regular tests on the drum drive mechanism. The regular test of the drum drive mechanism needs to be carried out under low power and shutdown conditions, and the reactor cannot output power normally during the test. However, the current regular test of the drum drive mechanism relies on engineering experience, and it is difficult to achieve a balance between safety and economy. Therefore, providing a method for determining the drum test cycle of a heat pipe reactor by a quantitative method is of positive significance for improving the safety and economy of the heat pipe reactor. Summary of the invention

[0003] The purpose of the present invention is to provide a method for determining the drum test cycle of a heat pipe reactor and to optimize the influence of the drum test cycle of the heat pipe reactor on the economic efficiency of the reactor. The present invention also provides a calculation device.

[0004] According to an embodiment of one aspect of the present invention, a method for determining a drum test cycle of a heat pipe reactor is provided. The method comprises the following steps:

[0005] Step a): Providing the jam probability Q of the drum drive mechanism of the heat pipe reactor T , the common cause jamming probability Q of the drum drive mechanism is calculated CCF ;

[0006] Step b): establishing a fault tree model of the failure of the drum drive mechanism, calculating the importance of the basic event of the drum drive mechanism jamming and the basic event of the common cause jamming of the drum drive mechanism in test cycles of different lengths, and the failure probability of the drum drive mechanism;

[0007] Step c): establishing the failure probability of the drum drive mechanism and the change curve of the importance with the test cycle as two reference curves;

[0008] Step d): taking the test cycle corresponding to the intersection of the two reference curves as the reference test cycle of the heat pipe reactor drum test cycle.

[0009] The method can make a quantitative evaluation of the test cycle of the drum drive mechanism, improve the safety of the regular test of the drum drive mechanism of the heat pipe reactor, and optimize the economy of the reactor.

[0010] Further, in some embodiments, in step a), Q T =λT / 2; T is the periodic test period and λ is the jamming failure rate of the drum drive mechanism.

[0011] Further, in some embodiments, in the step a),

[0012]

[0013] Where m is the total number of drums, k is the number of drums with common cause jamming, α i is the probability of common cause jamming of i drums.

[0014] Furthermore, in some embodiments, in the step b), the importance adopts Fussell Vesely importance.

[0015] Further, in some embodiments, in step b), the different time periods include one week, two weeks, one month, two months, three months, four months, five months, six months, nine months and one year.

[0016] Furthermore, in some embodiments, in the step c), when establishing the reference curve, the failure probability of the drum drive mechanism and the importance are dimensionally processed.

[0017] Furthermore, in some embodiments, the step d) also includes the following steps: providing a list of available periodic test cycles, comparing the available periodic test cycles in the list of available periodic test cycles with the reference test cycles, and using the available test cycle with the smallest difference with the reference test cycle and no longer than the reference test cycle as the heat pipe reactor drum test cycle.

[0018] According to an embodiment of another aspect of the present invention, a computing device is provided, which includes a memory and a processor, wherein the memory stores a computing program, and when the memory is executed by the processor, the method for determining the reactor drum test cycle provided by any of the aforementioned embodiments can be implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic flow chart of a method for determining a drum test cycle of a heat pipe reactor in one embodiment;

[0020] Figure 2A schematic diagram of a failure tree of a drum drive mechanism in one embodiment;

[0021] Figure 3 It is a schematic diagram of a reference curve in an embodiment.

[0022] The purpose of the above drawings is to explain the present invention in detail so that those skilled in the art can understand the technical concept of the present invention, but it is not intended to limit the present invention. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0024] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The phrase appearing in various locations in the specification does not necessarily refer to the same embodiment, nor is it limited to mutually exclusive independent or alternative embodiments. Those skilled in the art should be able to understand that the embodiments herein may be combined with other embodiments without causing structural conflicts.

[0025] In the description of this article, the terms "first", "second" and the like are only used to distinguish different objects, and cannot be understood as indicating relative importance or limiting the quantity, specific order or primary and secondary relationship of the described technical features. In the description of this article, the meaning of "plurality" is at least two.

[0026] Traditional reactors generally conduct heat generated by the reactor core through a coolant loop system, which includes complex pumps, pipes, valves, control systems, etc. The heat pipe reactor is a reactor that directly conducts the heat of the reactor core to the energy conversion device through heat pipes. It has a streamlined structural design, simple operating procedures, and high inherent safety. It is one of the important reactor types for small and medium-power nuclear energy.

[0027] The drum drive mechanism is widely used in heat pipe reactors. Its main functions include reactor startup, power regulation and shutdown, etc., which has an important impact on the safe operation of heat pipe reactors. The main components of the drum drive mechanism usually include a drive motor, a reset energy storage device (such as a spring), etc. The drum is cylindrical, and a part of the cylindrical surface is covered with a neutron absorber. Each drum is evenly arranged in the reflective layer outside the core. The drive motor controls the rate at which the drum absorbs neutrons by rotating all drums at the same time, thereby realizing the startup, power regulation and shutdown of the reactor. As the rotation angle of the drum continues to increase, the reset energy storage device continues to store energy. Under accident conditions, the drum is generally rotated to the shutdown position quickly by releasing potential energy through the reset energy storage device or driving the drive motor to achieve an emergency shutdown of the reactor.

[0028] The regular test of the drum drive mechanism is conducive to improving its reliability, especially reducing the failure probability of its shutdown function, thereby reducing the nuclear safety risk of the reactor. Therefore, during the operation of the heat pipe reactor, it is necessary to carry out regular tests on the drum drive mechanism. The regular test of the drum drive mechanism needs to be carried out under low power and shutdown conditions, mainly including full-stroke actions of operation and reset at different speeds under no load and load conditions. However, if the regular test of the drum drive mechanism is too frequent, it will reduce the economy of the heat pipe reactor and affect the service life of the drum drive mechanism. Therefore, it is of great significance to optimize the test cycle of the drum drive mechanism while ensuring the safety of the heat pipe reactor to improve the economy of the heat pipe reactor.

[0029] At present, there is no applicable quantitative analysis method for determining the periodic test cycle of the drum drive mechanism, and most of them are given qualitatively based on experience judgment. In view of the importance of the drum drive mechanism to the safe operation of heat pipe reactors, it is necessary to establish a set of quantitative methods for determining the periodic test cycle of the drum drive mechanism to ensure the scientificity and rationality of the selection of the periodic test cycle.

[0030] To this end, an embodiment of one aspect of the present invention provides a method for determining a drum test cycle of a heat pipe reactor. The method is based on fault tree analysis and combined with constraint index curve drawing to achieve quantitative evaluation of the test cycle and optimize the economic efficiency of the drum control mechanism periodic test plan on the basis of ensuring reactor safety.

[0031] Specifically, the process of this method is as follows Figure 1 as shown, and includes the following steps:

[0032] Step a): Determine the probability value of the basic event of jamming.

[0033] The failure rate of the drum drive mechanism being stuck (unable to reset) can usually be obtained based on the relevant equipment database or the manufacturer's test data, thereby obtaining the probability of the drum drive mechanism being stuck Q T , and its calculation formula is as follows:

[0034] Q T =λT / 2; T is the periodic test period and λ is the jamming failure rate of the drum drive mechanism.

[0035] For the common cause jamming of the drum drive mechanism, you can refer to NUREG / CR-5500 to perform a probability analysis on the basic event of common cause jamming of the drum drive mechanism. In NUREG / CR-5500, the common cause failure of components is quantified using the Alpha factor method. Considering the staggered test, in the m common cause component groups, the common cause basic event probability calculation formula for common cause failure of any k or more components is:

[0036]

[0037] Among them, α i is the probability of common cause jamming of i drums.

[0038] The drum drive mechanism drives a total of m drums, and its failure criterion is: any k or more common causes of jamming in the m drums. Based on this failure criterion and the above calculation formula, Q CCF and Q T , respectively, as the values ​​of the basic event of common cause jam of drum drive mechanism and the basic event of jam of drum drive mechanism in the fault tree.

[0039] Step b): Establish a fault tree model and perform analysis.

[0040] The quantitative analysis of fault trees mainly uses Boolean algebra operations, which can express top events as combinations of some basic events. Therefore, system failure (top event) can be expressed as a combination of basic event failures, and Boolean algebra operations can be used to find the basic event failure combination that causes system failure (i.e., the minimum cut set (MCS)), and then the probability of system failure can be calculated based on the failure probability of the basic events. Fussell Vesely importance (hereinafter referred to as "FV importance") represents the share of the probability of occurrence of a basic event or component failure or cut set in the top event probability, that is, their contribution to system failure. Among them, the calculation method of FV importance belongs to common knowledge in this field.

[0041] According to the drum drive mechanism common cause jam basic event and drum drive mechanism jam basic event value calculated in step a), as well as the failure criterion of the drum drive mechanism, a fault tree model of the drum drive mechanism failure is established. The structure of the fault tree model is as follows: Figure 2 Then, the fault tree analysis calculation method or analysis calculation software is used to calculate the failure probability of the top event of the fault tree and the FV importance of each basic event.

[0042] By setting different commonly used periodic test cycles (1 week, 2 weeks, 1 month, 2 months, 1 quarter, 4 months, 5 months, half a year, 3 quarters, 1 year, etc.), the values ​​of the common cause jamming basic events of the drum drive mechanism and the basic event of drum drive mechanism jamming are calculated respectively, thereby calculating the FV importance of the common cause jamming basic events of the drum drive mechanism and the basic event of drum drive mechanism jamming as well as the failure probability of the drum drive mechanism.

[0043] Step c): Draw a reference curve.

[0044] In order to determine the optimal periodic test cycle, two constraint indicators, namely the failure probability of the drum drive mechanism and the FV importance, are mainly investigated.

[0045] In a preferred embodiment, the failure probability of the drum drive mechanism and the FV importance are dimensionless. In a further preferred embodiment, Figure 3 As shown in the figure, the ratio of the failure probability of the drum drive mechanism to the failure probability of the drum drive mechanism corresponding to a periodic test period of 168 hours is used as a function to quantify the change of the failure probability of the drum drive mechanism with the periodic test period; the FV importance uses the ratio of the importance of the failure mode that contributes the most to the failure of the drum drive mechanism to the importance of the failure mode that contributes the second most as a function to quantify the change of FV importance with the periodic test period. This indicator is used to quantify the balance between the failure modes of the drum drive mechanism failure to avoid the "steep edge effect".

[0046] Therefore, the normalized failure probability of the drum drive mechanism and the FV importance curve with the periodic test cycle can be drawn as follows: Figure 3 shown.

[0047] Step d): Determine the reference test period.

[0048] According to step c), two reference curves are obtained, and the intersection of the reference curves is found, which is the test cycle of the drum drive mechanism with the best safety and economy in theory. The test cycle corresponding to this point is used as the reference test cycle.

[0049] During the actual operation of the reactor, there are one or more available drum drive mechanism test windows, taking into account the reactor operating status and management regulations. These time windows are organized into a list of available periodic test cycles and compared with the reference test cycle to determine the final heat pipe reactor drum drive device test cycle.

[0050] In a preferred embodiment, from the perspective of reactor safety, the reactor drum drive device test cycle should be selected with the shortest difference from the reference cycle within a test window that is not longer than the reference test cycle; or from an economic perspective, the cycle with the smallest difference from the reference cycle should be selected.

[0051] In the existing scheme, there is a lack of objective evaluation criteria for the balance between safety and economy in the process of designing periodic tests for the drum drive mechanism. In the technical scheme of the present invention, the objective failure probability is used to characterize safety, and the FV importance is used to characterize balance. By finding the intersection of the failure probability curve and the FV importance curve, and taking the test cycle length represented by the intersection as the objective comparison standard, a quantitative evaluation of the influence of different test cycle lengths on the drum drive mechanism is achieved. By adopting this method, the periodic test of the drum drive mechanism can be reasonably optimized, and the economy can be optimized while avoiding the "steep edge effect" of the FV importance (that is, the probability of a single failure factor is too high, resulting in the evaluation of reliability being excessively affected by a single factor).

[0052] The method for determining the drum test cycle of a heat pipe reactor provided in the above embodiment can be implemented by a computing device provided in an embodiment of another aspect of the present invention. The computing device includes a memory and a processor, wherein a computing program is stored in the memory, and when the computing program is executed by the processor, the method for determining the drum test cycle of a heat pipe reactor provided in the above embodiment can be implemented. The computing device can be configured as a general-purpose computer, or can be set as a special-purpose computing device, or can use a virtual machine or a cloud computing device. The computing program is a script or macro written using a general-purpose computing program, or can be a special-purpose computing program written based on a computer language.

[0053] The purpose of the above embodiments is to further explain the present invention in detail in conjunction with the accompanying drawings so that those skilled in the art can understand the technical concept of the present invention. Within the scope of the present invention, the optimization or equivalent replacement of the method steps involved, and the combination of the implementation methods in different embodiments without conflict of structure and principle, all fall within the protection scope of the present invention.

Claims

1. A method for determining a drum test cycle for a heat pipe reactor, characterized in that: The following steps are involved: Step a): Providing the jam probability Q of the drum drive mechanism of the heat pipe reactor T , the common cause jamming probability Q of the drum drive mechanism is calculated CCF ; Step b): establishing a fault tree model of the failure of the drum drive mechanism, calculating the importance of the basic event of the drum drive mechanism jamming and the basic event of the common cause jamming of the drum drive mechanism in test cycles of different lengths, and the failure probability of the drum drive mechanism; Step c): establishing the failure probability of the drum drive mechanism and the change curve of the importance with the test cycle as two reference curves; Step d): taking the test cycle corresponding to the intersection of the two reference curves as the reference test cycle of the heat pipe reactor drum test cycle.

2. The method for determining the drum test cycle of a heat pipe reactor according to claim 1, characterized in that: In the step a), Q T =λT / 2; T is the periodic test cycle, and λ is the jamming failure rate of the drum drive mechanism.

3. The method for determining the drum test cycle of a heat pipe reactor according to claim 1 or 2, characterized in that: In the step a), Where m is the total number of drums, k is the number of drums with common cause jamming, α i is the probability of common cause jamming of i drums.

4. The method for determining the drum test cycle of a heat pipe reactor according to claim 1, characterized in that: In the step b), the importance adopts the FussellVesely importance.

5. The method for determining the drum test cycle of a heat pipe reactor according to claim 1 or 4, characterized in that: In step b), the different time periods include one week, two weeks, one month, two months, three months, four months, five months, six months, nine months and one year.

6. The method for determining the drum test cycle of a heat pipe reactor according to claim 1 or 4, characterized in that: In the step c), when establishing the reference curve, the failure probability of the drum driving mechanism and the importance are dimensionally processed.

7. The method for determining the drum test cycle of a heat pipe reactor according to claim 1, characterized in that: The step d) also includes the following steps: providing a list of available periodic test cycles, comparing the available periodic test cycles in the list of available periodic test cycles with the reference test cycles, and using the available test cycle with the smallest difference with the reference test cycle and no longer than the reference test cycle as the heat pipe reactor drum test cycle.

8. A computing device, comprising a memory and a processor, characterized in that: The memory stores a computing program, and when the memory is executed by the processor, the method for determining that a heat pipe reactor is in a drum test cycle according to any one of claims 1 to 7 can be implemented.

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