Method and apparatus employing a vanadium neutron probe

Abstract

Disclosed herein is a method (300) regarding a power distribution of a reactor core of a nuclear facility, the method being performed on a general purpose computer. The method (300) includes measuring current values from a plurality of vanadium neutron probe assemblies (10) disposed in the reactor core of the nuclear facility (302); determining a measured relative core power distribution based on the measured current values (304); generating a measured core power distribution based on the measured relative core power distribution (306); and verifying that the reactor is operating within licensed core operational limits based at least in part on the measured core power distribution (308). Also disclosed herein is a vanadium neutron probe (1-5) assembly (10).

Description

[0001] Cross-reference to related applications

[0002] This application claims the benefit of U.S. Provisional Application No. 62 / 944,500, filed December 6, 2019, entitled “METHOD AND APPARATUS EMPLOYING VANADIUM SELF-POWERED NEUTRON DETECTORS”. The contents of that patent application are incorporated herein by reference. Background Technology

[0003] The vanadium neutron detector assembly requires a process to convert the measured detector element signal (which is in the form of the detected current level) into an equivalent neutron flux to generate a core power distribution measurement for a nuclear reactor core. The accuracy of the conversion and power distribution calculation is highly dependent on the nuclear methodology used. To use the measured power distribution results to meet the peak factor monitoring conditions for commercial reactors, extensive uncertainty analyses of the power distribution measurements are necessary, and the results must be submitted to the NRC for review and approval. This can potentially take years. This effort currently limits the application of this vanadium in-core detector to a limited set of systems. This also presents a barrier to selling this vanadium detector assembly to facilities that do not use a limited set of systems for reactor power distribution measurements. Summary of the Invention

[0004] The following summary is provided to facilitate understanding of some of the innovative features characteristic of the disclosed embodiments and is not intended to be a complete description. A full understanding of the various aspects of the embodiments can be obtained by considering the entire specification, claims, abstract, and drawings as a whole.

[0005] The methods and apparatus described herein greatly simplify vanadium neutron detector components (e.g., available from Westinghouse Electrical Company, Cranberry Township, Pennsylvania, United States). The implementation and use of vanadium detector components and many (if not all) types of core power distribution measurement methods currently in use.

[0006] This document discloses a method for power distribution in the reactor core of a nuclear facility, the method being executed on a general-purpose computer. The method includes: measuring current values ​​from a plurality of vanadium neutron detector assemblies disposed in the reactor core of the nuclear facility; determining a measured relative core power distribution based on the measured current values; generating a measured core power distribution based on the measured relative core power distribution; and verifying, at least in part, that the reactor is operating within permissible core operating limits based on the measured core power distribution.

[0007] This paper also discloses a vanadium neutron detector assembly comprising multiple vanadium neutron detector elements of unequal lengths. Each detector element is positioned such that it extends axially from one end of the fuel assembly toward the opposite end. Attached Figure Description

[0008] Various features of the embodiments described herein are particularly set forth in the appended claims. However, various embodiments of the organization and method of operation, and their advantages, can be understood from the following description taken in conjunction with the accompanying drawings:

[0009] Figure 1 This is a schematic diagram of a vanadium neutron detector assembly according to at least one aspect of this disclosure.

[0010] Figure 2 This is a bar graph showing exemplary axial flux distributions at different locations of the instrumented fuel assembly of this disclosure.

[0011] Figure 3 This is a flowchart illustrating an exemplary method of this disclosure.

[0012] The corresponding reference numerals indicate the corresponding portions throughout several views. The examples set forth herein illustrate various embodiments of the invention in one form, and such examples should not be construed as limiting the scope of the invention in any way. Detailed Implementation

[0013] Before explaining the various aspects of this disclosure in detail, it should be noted that the exemplary embodiments are not limited in application or use to the details of the construction and arrangement of the parts shown in the drawings and description. Exemplary embodiments may be implemented or incorporated in other aspects, variations, and modifications, and may be practiced or performed in a variety of ways. Furthermore, unless otherwise stated, the terminology and expressions used herein have been chosen for the convenience of the reader in describing exemplary embodiments and are not intended to limit the invention. Moreover, it should be understood that one or more of the aspects, expressions, and / or examples described below may be combined with any one or more of the other aspects, expressions, and / or examples described below.

[0014] According to the vanadium neutron detector assembly 10 of this disclosure, in Figure 1As shown in the diagram. For example, component 10 includes neutron detector elements 1-5. Figure 1 As shown, component 10 can be, for example... A detector assembly (ODA) has multiple detector elements 1-5, typically five. However, any suitable number of detector elements can be used, such as 2, 3, 4, 5, 6, 7, 8, 9, 10 or more. Detector elements 1-5 can each have different lengths. Figure 1 In the non-limiting example shown, vanadium detector element 1 can extend the full effective length of the fuel assembly, which can be, for example, 144 inches (approximately 3.66 meters). As used herein, a "full-length" detector element refers to such a vanadium neutron detector element that covers the entire effective length of the fuel assembly. The other detector elements (2-5) can be shorter than detector element 1. For example, detector element 2 can be 80% of the length of detector element 1, detector element 3 can be 60% of the length of detector element 1, and so on.

[0015] Additional details are disclosed in U.S. Patent No. 8,767,903, entitled “WIRELESS IN-CORE NEUTRONMONITOR,” issued July 1, 2014, and U.S. Patent No. 8,681,920, entitled “SELF-POWERED WIRELESS IN-CORE DETECTOR,” issued March 25, 2014. The full text of both documents is incorporated herein by reference.

[0016] Subtracting a measured detector current from another detector current provides an equivalent of a single detector measurement in the region between the ends of the longer and shorter detector elements, such as... Figure 1 As shown. For example, subtracting the current measured by detector element 2 from the current measured by detector element 1 provides an equivalent measurement by a single detector in the non-overlapping areas of 1 and 2. Component 10 may also include a multi-pin connector 12, a connector back housing 14, a flexible tube 16, and a sheath 18. One or more of the connector back housing 14, flexible tube 16, and sheath 18 may include stainless steel. Sheath 18 may include detector elements 1-5. Sheath may also house thermocouple 22. However, in other embodiments, thermocouple 22 may not be included.

[0017] At Westinghouse Electric Company BEACON In this process, the nuclear method conversion corresponds to the predicted neutron flux over the region covered by the detector signal difference, and the predicted neutron flux is converted into a predicted detector current using analytical relations developed for vanadium detector elements 1-5. The ratio of the measured current to the predicted current from all detector assemblies in the reactor core can be used to adjust the predicted reactor power distribution to produce a measured reactor power distribution used to determine whether the reactor is operating within the permissible core peak factor limits. The method used to convert the predicted neutron flux into the predicted detector current can affect the accuracy of the measured core power distribution and is based on the specific nuclear method used.

[0018] Additional details are disclosed in U.S. Patent Publication No. 2011 / 0268239 entitled “METHOD OF CALIBRATING EXCOREDETECTORS IN A NUCLEAR REACTOR”, published on November 3, 2011, which is incorporated herein by reference in its entirety.

[0019] This paper describes a method that can be advantageously used to avoid the dependence of power distribution measurement accuracy on such nuclear methods by advantageously avoiding the need to convert the predicted neutron flux distribution into detector current.

[0020] refer to Figure 3 Method 300 may include measuring 302 current values ​​from multiple vanadium neutron detector assemblies. The neutron detector assemblies may be located in the reactor core of a nuclear facility. Method 300 may include determining 304 a measured relative core power distribution based on the measured current values. Method 300 may include generating 306 a measured core power distribution based on the measured relative core power distribution. Method 300 may include verifying, at least in part, that the reactor is operating within permissible core operation limits based on the measured core power distribution. Method 300 may be performed on a general-purpose computer.

[0021] In various aspects, determining 304 may include measuring the total reactor relative power level (Q). T A calibration relationship is established between the current measured from all detector 1 elements (e.g., full-length detector elements) at the instrumented radial core location i (I1(i)) and the sum of all measured currents. This relationship will result in the average current of all detector 1 elements in all instrumented fuel cells in the core. It should be noted that, for example, approximately one-third of the fuel cells in the exemplary core described herein are instrumented with an OPARSSEL-type vanadium detector assembly or any other suitable vanadium detector assembly. This relationship takes the form of:

[0022]

[0023] Where K is the measured reactor relative power level (Q) T ) and corresponding The slope of the relationship diagram is the measured slope. N is the number of instrumented fuel assemblies in the reactor. Q is calculated by dividing the measured reactor thermal power (e.g., measured using secondary calorimetric data including flow rate, temperature, pressure, and enthalpy change) by the maximum permissible thermal power. T .

[0024] The relationship between reactor thermal power and average in-core detector output current is reflected in the value of K determined in Equation 1. Equation 1 confirms that the value of K is related to the reactor's relative power level (Q). T The relationship between K and the detector element is linear. The value of K includes the detector neutron sensitivity per unit length and the average relative power of the fuel assembly containing the detector element. During the manufacturing process, the neutron sensitivity value for each detector element is initially captured. Manufacturing data indicate that this value is substantially equal for each detector element, but it should be noted that this neutron sensitivity value decreases over time, meaning that for a given neutron flux value within the core, the current output by the detector will decrease over time. Once the optimal estimate is available, it is expected to be updated with the optimal estimate. Calibration is also expected to be performed during the power rise from 0–50% RTP (before monitoring the power distribution), and since the relationship is known to be linear, a calibration of 50–100% is used.

[0025] In addition to the above, the relationship between the relative reactor power level of 304 and the power of any fuel assembly containing the detector assembly can be determined based on the detector 1 current. Process 304 may also include determining the relative assembly power Q of 304 at core location i using the following expression. R (i) involves determining the core relative to the total reactor power level (Q) at each instrumented fuel assembly (each instrumented fuel assembly is located at a known location i in the core). T Power of:

[0026]

[0027] Q R (i) can be directly expressed by the measured current, i.e., without a K value, as shown in the following equation:

[0028]

[0029] It includes an optional correction factor μ i It is equal to the ratio of the length of detector 1 at core location i to the average length of all detectors 1. Knowing that all detectors 1 have the same length, the correction factor μ... iIt is unnecessary. Those skilled in the art can develop other correction factors that take into account differences in detector consumption and manufacturing sensitivity in a similar manner. In this case, Q R The measurement of (i) advantageously does not require any nuclear design data.

[0030] Assuming equal neutron sensitivity in the detectors, the axial relative power distribution can be represented as follows. For each instrumentation location / assembly i in the core, which can be referred to as the radial location within the approximately circular core, determining 304 may include determining the relative axial power distribution at height j of each axial region, such as... Figure 2 As shown, the axial region height j is in each of these instrumented fuel assemblies i, P j (i) represents the region between one end of a given detector with flux values ​​F1, F2, etc., and the end of the next longest detector. Assuming the neutron sensitivity per unit length is equal, the following expression is used:

[0031]

[0032] ΔI j The value of (i) represents the difference in current measured from the detector at positions j=1, j=2, etc., and represents the flux values ​​F1, F2, etc., where:

[0033] ΔI1(i)=I1(i)-I2(i)

[0034] ΔI2(i)=I2(i)-I3(i)

[0035] etc......

[0036] Equation 4 provides an expression for how much power fuel assembly i produces at each vertical position j relative to the core power. The measured radial and axial relative reactor power distribution data can be extrapolated to the appropriate axial node distribution and non-instrumented core locations using any method employed in current core power distribution measurement software.

[0037] The kernel method for calculating the measured core power distribution can advantageously replace the method of adjusting the predicted relative core power distribution using the measured relative core power distribution described herein, thereby producing a measured core power distribution that can be used to verify that the reactor is operating within permissible core operation limits. This method would greatly simplify and reduce the requirements that allow for operation without the use of known BEACON kernels. The time and cost required for customers to implement ODA.

[0038] The process outlined herein advantageously allows for the measurement of reactor power distribution using vanadium ODA-type detectors without requiring extensive re-licensing work on nuclear methods. Successful implementation of the method described in this disclosure will enable the measurement of reactor power distribution without using... To implement ODA-type detector hardware quickly and cheaply in factories.

[0039] The improved method 300 can be executed on any general-purpose computer and includes: 302 measuring current values ​​from various vanadium detectors in the core of a nuclear facility; 304 determining a measured relative core power distribution based on the measured current values; adjusting a predicted relative core power distribution based on the measured relative core power distribution; and 306 generating a measured core power distribution that can be used to verify that the reactor is operating within permissible core operation limits. The disclosed and claimed concepts also include a nuclear facility with a nuclear core and a computer on which the following steps are performed: measuring current values ​​from various vanadium detectors in the core of the nuclear facility; determining a measured relative core power distribution based on the measured current values; adjusting a predicted relative core power distribution based on the measured relative core power distribution; and generating a measured core power distribution that can be used to verify that the reactor is operating within permissible core operation limits.

[0040] Various aspects of the subject matter described herein are illustrated in the following embodiments.

[0041] Example 1 – A method for power distribution in the reactor core of a nuclear facility, the method being performed on a general-purpose computer and comprising: measuring current values ​​from a plurality of vanadium neutron detector assemblies disposed in the reactor core of the nuclear facility; determining a measured relative core power distribution based on the measured current values; generating a measured core power distribution based on the measured relative core power distribution; and verifying, at least in part, that the reactor is operating within permissible core operating limits based on the measured core power distribution.

[0042] Example 2 – The method as described in Example 1 further includes adjusting at least one of the predicted relative core power distribution based on the measured relative core power distribution and a model that can be used to predict the relative core power distribution.

[0043] Example 3 – The method as described in Example 1 or 2, wherein determining the measured relative core power distribution includes creating a calibration relationship between the measured total reactor relative power level and the sum of all measured currents from full-length detector elements at multiple instrumented radial core locations.

[0044] Example 4 – The method as described in any one of Examples 1 to 3, wherein determining the measured relative core power distribution includes determining the relative fuel assembly power of at least one core fuel assembly relative to the measured total reactor relative power level of the reactor core.

[0045] Example 5 – The method as described in any one of Examples 1 to 4, wherein determining the measured relative core power distribution includes determining the relative axial power distribution of each axial region height for each instrumented core fuel assembly.

[0046] Example 6 – The method as described in any one of Examples 1 to 5, wherein each of the plurality of vanadium detector assemblies comprises a plurality of vanadium neutron detector elements of unequal lengths, and wherein each detector element extends axially from one end of the fuel assembly toward the opposite end of the fuel assembly.

[0047] Example 7 – The method as described in Example 6, wherein each of the plurality of vanadium detector assemblies comprises a plurality of vanadium neutron detector elements of unequal lengths, and wherein each assembly comprises a full-length detector element and at least one additional detector element, the length of which is less than the full length.

[0048] Example 8 – A nuclear facility comprising: the computer on which operations as described in any one of Examples 1 to 7 are performed; the nuclear reactor core; and the plurality of vanadium neutron detector assemblies located within the reactor core.

[0049] Example 9 – A vanadium neutron detector assembly comprising a plurality of vanadium neutron detector elements of unequal length, wherein each detector element is positioned to extend axially from one end of the fuel assembly toward the opposite end.

[0050] Example 10 – A vanadium neutron detector assembly as described in Example 9, wherein the plurality of vanadium neutron detector elements include a full-length detector element and at least one additional detector element, the length of which is less than the full length.

[0051] Unless otherwise stated, as is apparent from the foregoing disclosure, it should be understood that throughout the foregoing disclosure, discussions using terms such as “processing,” “computing,” “operation,” “determining,” and “displaying” refer to the actions and processes of a computer system or similar electronic computing device that manipulate and convert data represented as physical (electronic) quantities in the registers and memories of the computer system into other data represented similarly as physical quantities in the memory or registers of the computer system or other such information storage, transmission, or display devices.

[0052] One or more components may be referred to herein as “configured as,” “configurable as,” “operable / operable as,” “adaptable / adaptable,” “capable of,” “compliant / compliant,” etc. Those skilled in the art will recognize that, unless the context otherwise requires, “configured as” generally encompasses active state components and / or inactive state components and / or standby state components.

[0053] Those skilled in the art will recognize that, in general, the terms used herein, and especially in the appended claims (e.g., the body of the appended claims), are typically intended as “open-ended” terms (e.g., the term “comprising” should be interpreted as “comprising but not limited to,” the term “having” should be interpreted as “having at least,” the term “including” should be interpreted as “including but not limited to,” etc.). Those skilled in the art will further understand that if a particular number of statements in the introduced claims is intentional, such intention will be explicitly stated in the claims, and without such statements, such intention does not exist. For example, to aid understanding, the appended claims may contain the use of the introductory phrases “at least one” and “one or more” to introduce the claims. However, the use of such a phrase should not be interpreted as implying that a claim statement introduced by the indefinite article “a (a or an)” limits any particular claim containing such an introduced claim statement to only one such claim, even when the same claim includes the introductory phrase “one or more” or “at least one” and the indefinite article such as “a (a or an)” (e.g., “a (a and / or an)” should generally be interpreted as meaning “at least one” or “one or more”); the same applies to the use of definite articles used to introduce a claim statement.

[0054] Furthermore, even if a specific number of introduced claims are explicitly stated, those skilled in the art will recognize that such a statement should generally be interpreted as referring to at least the number stated (e.g., a blank statement of "two statements" without other modifiers generally refers to at least two statements, or two or more statements). Moreover, in cases where conventions such as "at least one of A, B, and C" are used, such constructions are generally understood by those skilled in the art to be established in the sense of the convention (e.g., "a system having at least one of A, B, and C" will include, but is not limited to, systems having a single A, a single B, a single C, A and B together, A and C together, B and C together, and / or A, B, and C together). In cases where conventions such as “at least one of A, B, or C” are used, such constructions are generally understood by those skilled in the art to be established in the sense of the convention (e.g., “a system having at least one of A, B, or C” will include, but is not limited to, systems having a single A, a single B, a single C, A and B together, A and C together, B and C together, and / or A, B, and C together). Those skilled in the art will further understand that, typically, whether in the specification, claims, or drawings, separating words and / or phrases presenting two or more alternative terms should be understood to account for the possibility of including one of these terms, any of these terms, or both terms, unless the context otherwise indicates. For example, the phrase “A or B” should generally be understood to include the possibility of “A” or “B” or “A and B”.

[0055] With respect to the appended claims, those skilled in the art will understand that the operations listed herein can generally be performed in any order. Furthermore, although various operation flowcharts are presented in sequence, it should be understood that the various operations may be performed in a different order than shown, or may be performed simultaneously. Unless the context otherwise requires, embodiments of such alternative ordering may include overlapping, interleaving, interruption, reordering, incremental, preparatory, supplementary, simultaneous, reverse, or other altered orderings. Moreover, unless the context otherwise requires, terms such as “in response to,” “related,” or other past tense adjectives are generally not intended to exclude such variations.

[0056] It is worth noting that any reference to "an aspect," "one aspect," "an example," or "an example" implies that the specific feature, structure, or characteristic described in connection with that aspect is included in at least one aspect. Therefore, phrases such as "in an aspect," "in one aspect," "in an example," or "in an example" appearing in different places throughout the specification do not necessarily refer to the same aspect. Furthermore, specific features, structures, or characteristics can be combined in any suitable manner with one or more aspects.

[0057] Any patent applications, patents, non-patent publications, or other disclosures cited in this specification and / or listed in any application data sheets are incorporated herein by reference, provided that the incorporated material is not inconsistent with this specification. Therefore, and to the extent necessary, the disclosures set forth herein supersede any conflicting material incorporated herein by reference. Any material, or portions thereof, allegedly incorporated herein by reference that conflicts with existing definitions, statements, or other disclosures set forth herein is incorporated only to the extent that it will not create a contradiction between the incorporated material and existing disclosures.

[0058] The terms “comprise” (and any form of inclusion, such as “comprise” and “comprising”), “have” (and any form of having, such as “has” and “having”), “include” (and any form of inclusion, such as “includes” and “including”), and “contains” (and any form of containing, such as “contains” and “containing”) are open-ended connecting verbs. Therefore, a system that “comprises,” “has,” “includes,” or “contains” one or more elements possesses, but is not limited to, those one or more elements. Similarly, the elements of a system, apparatus, or device that “comprises,” “has,” “includes,” or “contains” one or more features possess those one or more features, but are not limited to having only those one or more features.

[0059] Unless otherwise stated, the terms “about” or “approximately” as used in this disclosure mean an acceptable error for a particular value as determined by one of ordinary skill in the art, depending in part on how the value is measured or determined. In some embodiments, the terms “about” or “approximately” mean within 1, 2, 3, or 4 standard deviations. In some embodiments, the terms “about” or “approximately” mean within 50%, 20%, 15%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, or 0.05% of a given value or range.

[0060] Any range of values ​​listed in this article is intended to include all subranges contained therein. For example, the range “1 to 10” is intended to include all subranges between the listed minimum value of 1 and the listed maximum value of 10 (inclusive), that is, a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0061] In summary, many beneficial effects resulting from employing the concepts described herein have been described. For illustrative and descriptive purposes, one or more of the specific embodiments described above have been provided. It is not intended to be exhaustive or limiting to the precise forms disclosed. Modifications or variations may be made based on the foregoing teachings. One or more forms were chosen and described to illustrate the principles and practical applications, thereby enabling those skilled in the art to utilize various forms and modifications to suit a particular intended use. The claims submitted herein are intended to define the general scope.

Claims

1. A method for measuring and verifying the power distribution of a reactor core in a nuclear facility, the method being performed on a general-purpose computer and comprising: Measure the current values ​​from multiple vanadium neutron detector assemblies installed in the reactor core of the nuclear facility; The measured relative core power distribution is determined based on the measured current value, wherein determining the measured relative core power distribution includes measuring the total reactor relative power level Q. T A calibration relationship is established between the sum of all measured current values ​​from the plurality of vanadium neutron detector assemblies at the instrumented radial core location i (I1(i)) and the following formula: in: Q T It measures the total relative power level of the reactor. K is the measured total reactor relative power level (Q). T ) and corresponding The slope of the relationship graph is measured. N is the number of the plurality of vanadium neutron detector components. i is the instrumented radial core position, and I1 is the measured current value; The predicted relative core power distribution is adjusted based on the determined measured relative core power distribution; The measured core power distribution is generated based on the adjusted predicted relative core power distribution; and The reactor is being verified, at least in part, to be operating within permissible core operating limits, based on the resulting measured core power distribution.

2. The method of claim 1, wherein determining the measured relative core power distribution comprises determining the relative fuel assembly power of at least one core fuel assembly relative to the measured total reactor relative power level of the reactor core.

3. The method of claim 1 or 2, wherein determining the measured relative core power distribution comprises determining the relative axial power distribution of each axial region height for each instrumented core fuel assembly.

4. The method of claim 1 or 2, wherein each of the plurality of vanadium neutron detector assemblies comprises a plurality of vanadium neutron detector elements of unequal lengths, and wherein each detector element extends axially from one end of the fuel assembly toward the opposite end of the fuel assembly.

5. The method of claim 4, wherein each of the plurality of vanadium neutron detector assemblies comprises a plurality of vanadium neutron detector elements of unequal lengths, and wherein each assembly comprises a full-length detector element and at least one additional detector element, the additional detector element being shorter than the full length.

6. A nuclear facility, said nuclear facility comprising: A computer, on which the method as described in any one of claims 1 to 5 is executed; Nuclear reactor core; as well as Multiple vanadium neutron detector assemblies are located in the reactor core.

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