CN-121983361-A - Method and device for determining value of control rod of nuclear reactor

CN121983361ACN 121983361 ACN121983361 ACN 121983361ACN-121983361-A

Abstract

The embodiment of the application provides a method and a device for determining the value of a control rod of a nuclear reactor. The method comprises the steps of obtaining the burnup depth and the cooling time of a fuel assembly in a nuclear reactor and the source range counting rate in an initial state and a control rod group inserting state, calculating according to the burnup depth and the cooling time to obtain an initial subcritical correction factor, calculating according to the initial subcritical correction factor and the source range counting rate in each state to obtain a measurement subcritical degree in each state, iteratively updating the initial subcritical correction factor according to the measurement subcritical degree until the iteration stopping condition is met, taking the measurement subcritical degree obtained in the last time as a target measurement subcritical degree, and calculating according to the target measurement subcritical degree to obtain the control rod value of the control rod group. The embodiment of the application can dynamically optimize the correction factor by combining the actual measurement counting rate, improve the accuracy of the value measurement result of the control rod, and achieve the purpose of monitoring the difference between the design model and the actual reactor core.

Inventors

CHEN JUN
LU HAOLIANG
LI WEN
YANG YUYING
YI LIN
LI JINGGANG
LIU KANGNING
LI YONGXIN
GAO WEI
TAN SHIJIE

Assignees

中广核研究院有限公司
岭澳核电有限公司

Dates

Publication Date: 20260505
Application Date: 20251203

Claims (10)

1. A method of determining a value of a control rod of a nuclear reactor, the method comprising: acquiring the burnup depth of a fuel assembly in a nuclear reactor, the cooling time of the fuel assembly and the source range count rate of the nuclear reactor in an initial state and in a control rod group insertion state, wherein the source range count rate is neutron count recorded by an endogenous range detector in unit time; Calculating according to the burnup depth and the cooling time to obtain an initial subcritical correction factor; calculating according to the initial subcritical correction factor and the source range count rate of the nuclear reactor in each of a plurality of states, wherein the states comprise the initial state and the insertion state, so as to obtain a measurement subcritical degree in each state; Updating the initial subcritical correction factor according to the measured subcritical degree in each state to obtain a temporary subcritical correction factor; The temporary subcritical correction factor is used as the initial subcritical correction factor, the step of calculating according to the initial subcritical correction factor and the source range count rate of the nuclear reactor in each of a plurality of states to obtain the measurement subcritical degree in each state is carried out until the iteration stop condition is met, and the measurement subcritical degree in each state obtained last time is used as the target measurement subcritical degree in each state; And calculating according to the target measurement subcritical degree in each state to obtain the control rod value of the control rod group.
2. The method of claim 1, wherein said calculating based on said burn-up depth and said cooling time results in an initial subcritical correction factor comprising: Calculating according to steady-state distribution of a three-dimensional detector response factor and neutron fluence rate to obtain a space correction factor, wherein the three-dimensional detector response factor is the probability that neutrons generated in each region of a reactor core are counted after being transported to the source range detector; Calculating according to the pre-acquired effective multiplication factor of the passive reactor core and the pre-acquired effective multiplication factor of the active reactor core to obtain an external neutron source influence factor; And multiplying the space correction factor and the external neutron source influence factor to obtain the initial subcritical correction factor.
3. The method of claim 2, wherein the calculating based on the three-dimensional detector response factor and the steady-state distribution of neutron fluence rates to obtain the spatial correction factor comprises: Obtaining the three-dimensional detector response factor by simulating a transport process of neutrons in the nuclear reactor from a fuel rod to the source range detector; Calculating according to the burnup depth and the cooling time to obtain the external neutron source intensity of each section in the fuel assembly; performing nuclear reactor operation simulation according to the external neutron source intensity of each section in the fuel assembly to obtain steady-state distribution of neutron fluence rate; And calculating according to the three-dimensional detector response factor and the steady-state distribution of the neutron fluence rate to obtain the space correction factor.
4. A method according to claim 3, wherein the obtaining the three-dimensional detector response factor by simulating a transport of neutrons in the nuclear reactor from a fuel rod to the source range detector comprises: And counting neutron reaction rates on a sensitive section of the source range detector in the process of simulating the transportation of neutrons in the nuclear reactor from a fuel rod to the source range detector, and dividing the quantity of neutrons generated in each region of the reactor core to the source range detector by the total quantity of neutrons generated in the corresponding region of the reactor core to obtain the three-dimensional detector response factor.
5. The method of claim 1, wherein the calculating based on the initial subcritical correction factor and the source turndown count rate of the nuclear reactor in each of a plurality of states to obtain a measured subcritical degree in each state comprises: Correcting the source range count rate in each state according to the initial subcritical correction factor to obtain a corrected source range count rate in each state; performing reciprocal calculation on the corrected source range count rate in each state to obtain the reciprocal count rate in each state; and linearly fitting the countdown rate and the theoretical subcritical degree in each state to obtain the measurement subcritical degree in each state.
6. The method of claim 1, wherein updating the initial subcritical correction factor based on the measured subcritical degree in each state to obtain a temporary subcritical correction factor comprises: performing multiple parameter punishment treatment on the control rod group to obtain a passive core effective proliferation factor corresponding to each parameter punishment treatment and a subcritical correction factor corresponding to each parameter punishment treatment, wherein the nuclear density and/or the nuclear size adjusted by each parameter punishment treatment are different; Obtaining a mapping relation between the subcritical correction factors and the passive core effective multiplication factors according to the passive core effective multiplication factors corresponding to each parameter punishment processing and the subcritical correction factors corresponding to each parameter punishment processing; acquiring corresponding passive core effective multiplication factors in each state according to the measurement subcritical degree in each state; And acquiring a subcritical correction factor corresponding to the passive core effective multiplication factor in each state from the mapping relation as a temporary subcritical correction factor in each state.
7. The method of claim 1, wherein the calculating according to the target measurement sub-criticality for each state to obtain the control rod value for the control rod set comprises: And obtaining the control rod value of the control rod group according to the ratio of the target measurement subcritical degree of the nuclear reactor in the control rod group insertion state to the target measurement subcritical degree of the nuclear reactor in the initial state.
8. The method of claim 1, wherein obtaining a source turndown ratio of the nuclear reactor in an initial state and the nuclear reactor in a control rod set insertion state comprises: Taking the core state of all control rods in the nuclear reactor as the initial state, and collecting the source range count rate in the initial state; And inserting the control rod group into the reactor core to a preset position, and collecting the source range count rate under the insertion state of the control rod group.
9. The method of claim 1, wherein the iteration stop condition includes a difference between measured sub-criticalities of two adjacent iteration calculations being less than a preset threshold.
10. A control rod value determination apparatus for a nuclear reactor, the apparatus comprising: The acquisition module is used for acquiring the burnup depth of a fuel assembly in the nuclear reactor, the cooling time of the fuel assembly and the source range count rate of the nuclear reactor in an initial state and in a control rod group insertion state, wherein the source range count rate is the neutron count recorded by an endogenous range detector in unit time; the first calculation module is used for calculating according to the burnup depth and the cooling time to obtain an initial subcritical correction factor; the second calculation module is used for calculating according to the initial subcritical correction factor and the source range count rate of the nuclear reactor in each of a plurality of states, so as to obtain a measurement subcritical degree in each state, wherein the plurality of states comprise the initial state and the insertion state; The updating module is used for updating the initial subcritical correction factor according to the measured subcritical degree in each state to obtain a temporary subcritical correction factor; The iteration module is used for taking the temporary subcritical correction factor as the initial subcritical correction factor, skipping to the step of calculating according to the initial subcritical correction factor and the source range count rate of the nuclear reactor in each of a plurality of states to obtain the measurement subcritical degree in each state, and executing until the iteration stopping condition is met, and taking the measurement subcritical degree in each state obtained last time as the target measurement subcritical degree in each state; And the third calculation module is used for calculating according to the target measurement subcritical degree in each state to obtain the control rod value of the control rod group.

Description

Method and device for determining value of control rod of nuclear reactor Technical Field The application relates to the technical field of nuclear power, in particular to a method and a device for determining the value of a control rod of a nuclear reactor. Background In the physical start-up and debugging process of nuclear reactors, subcritical rod engraving is a key means for measuring the value of control rods. Under the deep subcritical working condition, the physical characteristics of the nuclear reactor core no longer meet the point reactor assumption, so that the actual subcritical degree of the core is difficult to accurately obtain directly through the on-site source range measurement signal. In the prior art, a mode of introducing a theoretical correction factor is generally adopted to correct a source range measurement signal so as to realize indirect measurement of subcritical degree. However, the existing method introduces more theoretical correction amount in the correction process, so that excessive correction of the measured signal is easy to cause, the actual situation of the reactor core cannot be truly reflected by the measurement result, and the accuracy of the measurement result of the value of the control rod is reduced. Disclosure of Invention The embodiment of the application mainly aims to provide a method and a device for determining the value of a control rod of a nuclear reactor, and aims to solve the problem that a theoretical model pollutes a subcritical degree measurement result in the prior art and cannot reflect the actual state of a reactor core, and the accuracy of the value measurement result of the control rod of the nuclear reactor is improved by combining an actually measured counting rate dynamic optimization correction factor. To achieve the above object, a first aspect of an embodiment of the present application provides a method for determining a value of a control rod of a nuclear reactor, the method comprising: acquiring the burnup depth of a fuel assembly in a nuclear reactor, the cooling time of the fuel assembly and the source range count rate of the nuclear reactor in an initial state and in a control rod group insertion state, wherein the source range count rate is neutron count recorded by an endogenous range detector in unit time; Calculating according to the burnup depth and the cooling time to obtain an initial subcritical correction factor; calculating according to the initial subcritical correction factor and the source range count rate of the nuclear reactor in each of a plurality of states, wherein the states comprise the initial state and the insertion state, so as to obtain a measurement subcritical degree in each state; Updating the initial subcritical correction factor according to the measured subcritical degree in each state to obtain a temporary subcritical correction factor; The temporary subcritical correction factor is used as the initial subcritical correction factor, the step of calculating according to the initial subcritical correction factor and the source range count rate of the nuclear reactor in each of a plurality of states to obtain the measurement subcritical degree in each state is carried out until the iteration stop condition is met, and the measurement subcritical degree in each state obtained last time is used as the target measurement subcritical degree in each state; And calculating according to the target measurement subcritical degree in each state to obtain the control rod value of the control rod group. In some embodiments, the calculating according to the burnup depth and the cooling time to obtain an initial subcritical correction factor includes: Calculating according to steady-state distribution of a three-dimensional detector response factor and neutron fluence rate to obtain a space correction factor, wherein the three-dimensional detector response factor is the probability that neutrons generated in each region of a reactor core are counted after being transported to the source range detector; Calculating according to the pre-acquired effective multiplication factor of the passive reactor core and the pre-acquired effective multiplication factor of the active reactor core to obtain an external neutron source influence factor; And multiplying the space correction factor and the external neutron source influence factor to obtain the initial subcritical correction factor. In some embodiments, the calculating according to the three-dimensional detector response factor and the steady-state distribution of the neutron fluence rate to obtain the spatial correction factor includes: Obtaining the three-dimensional detector response factor by simulating a transport process of neutrons in the nuclear reactor from a fuel rod to the source range detector; Calculating according to the burnup depth and the cooling time to obtain the external neutron source intensity of each section in the fuel assembly; performing nuclear r