A dynamic bar drawing method based on transient spatial factor

Abstract

A dynamic rod worth method based on transient spatial factor, the transient spatial factor of control rod value is obtained by theoretical calculation, and is applied to the dynamic rod worth process to obtain the measured value of control rod value. According to the control rod moving information of the dynamic rod worth process, the static value of the control rod is calculated by core steady-state simulation calculation; the change of the power range detector current signal calculation value with time is obtained by core transient simulation calculation, and the inverse point reactor equation is substituted to obtain the dynamic value of the control rod; the transient spatial factor is obtained according to the static value of the control rod and the dynamic value of the control rod; in engineering application, based on the current signal measured value of the power range detector, the inverse point reactor equation is calculated, the transient spatial factor is applied, and finally the measured value of the control rod value is obtained. The method only needs one transient spatial factor to complete the high-precision dynamic rod worth test, and the data of the static correction factor and the dynamic correction factor of each control rod rod position state required by the traditional dynamic rod worth method are saved, and the method has high engineering application value.

Description

Technical Field

[0001] This invention relates to the field of pressurized water reactor core physics calculation technology, specifically to a dynamic bar marking method based on transient space factor. Background Technology

[0002] Control rod value measurement is a crucial component of commercial pressurized water reactor (PWR) startup physics tests, directly impacting PWR control and safety. Therefore, accurate control rod value measurement is paramount. Traditional methods for control rod value measurement include boron measurement and rod replacement methods. However, both methods require extremely long measurement times, resulting in poor economic efficiency and generating significant amounts of boron-containing wastewater. Consequently, most nuclear power plants currently employ the dynamic rod marking method for control rod value measurement. This method offers faster measurement speeds, independent measurement of each control rod's value, eliminates interference effects, and provides the accuracy required for engineering acceptance criteria. However, the commonly used dynamic rod marking method requires calculating static and dynamic space factors for each control rod position, leading to complex data sets and significant inconvenience in on-site application during nuclear power plant startup physics tests. Summary of the Invention

[0003] To address the problems of cumbersome data and inconvenient operation caused by the large number of static and dynamic space factors required by current dynamic bar marking methods, this invention aims to provide a dynamic bar marking method based on transient space factors. This method calculates transient space factors through core simulation based on the control rod movement information during the dynamic bar marking process, and then applies these transient space factors to engineering measurement data to obtain the measured value of the control rod. This invention requires only one transient space factor to complete high-precision dynamic bar marking tests, eliminating the cumbersome data problem of calculating static and dynamic space factors for each control rod's position state required by traditional dynamic bar marking methods, and thus has high engineering application value.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A dynamic bar marking method based on transient space factor includes the following steps:

[0006] Step 1: Use the pressurized water reactor fuel management program to perform steady-state numerical simulation calculations for the control rods in two states: when they are at the top of the reactor core and when they are at the bottom of the reactor core, to obtain the calculated static value of the control rods;

[0007] Step 2: Based on the movement information of the control rod from the top to the bottom of the core during the dynamic rod etching process, the pressurized water reactor fuel management program is used to perform transient numerical simulation calculations on the movement process of the control rod to obtain the change of the simulated current signal value of the power range detector over time.

[0008] Step 3: input the current signal analog value of the power range detector in step 2 into the inverse point reactor equation, and calculate the control rod dynamic value calculation value introduced by the movement of the control rod from the top of the reactor core to the bottom of the reactor core;

[0009] Step 4: calculate the transient spatial factor according to the control rod static value calculation value in step 1 and the control rod dynamic value calculation value in step 3;

[0010] Step 5: in actual engineering application, the control rod dynamic value measured value is obtained according to the current signal recorded by the power range detector and the inverse point reactor equation calculation of the reactivity instrument, and the control rod value measured value is finally obtained by applying the transient spatial factor in step 4.

[0011] Preferably, the implementation process of step 1 is as follows:

[0012] 1) The steady-state neutron diffusion calculation of the state of the control rod located at the top of the reactor core is performed by using the pressurized water reactor fuel management program, and the static reactivity calculation value of the control rod located at the top of the reactor core is obtained

[0013] 2) The steady-state neutron diffusion calculation of the state of the control rod located at the bottom of the reactor core is performed by using the pressurized water reactor fuel management program, and the static reactivity calculation value of the control rod located at the bottom of the reactor core is obtained

[0014] 3) The control rod static value calculation value introduced by the movement of the control rod from the top of the reactor core to the bottom of the reactor core is calculated

[0015]

[0016] Preferably, the implementation process of step 2 is as follows:

[0017] 1) In the process of measuring the control rod value by using the dynamic rod marking method, the control rod moves from the top of the reactor core to the bottom of the reactor core at a fixed driving speed, and the transient numerical simulation calculation of the movement of the control rod from the top of the reactor core to the bottom of the reactor core is performed by using the pressurized water reactor fuel management program, and the three-dimensional power distribution of the reactor core is obtained k (t), k represents the three-dimensional space grid index, and t represents time;

[0018] 2) According to the geometric structure and material arrangement of the reactor core, the reactor core model from the reactor core fuel assembly to the power range detector is established, the power range detector is divided into multiple sections in the axial direction, and the response function ω of each section of the power range detector is calculated by using the conjugate neutron transport equation j,k, j represents the index of the number of the range detector, k represents the index of the number of the three-dimensional space grid, the response function of the range detector represents the contribution of the three-dimensional power distribution of the reactor core to the analog value of the current signal of the range detector;

[0019] 3) According to the response function ω j,k and the change of the three-dimensional power distribution of the reactor core with time Pk(t) during the movement of the control rod, the change of the analog value of the current signal of the range detector with time during the movement of the control rod is calculated s represents the abbreviation of the English word simulation,

[0020]

[0021] In the formula, K represents the total number of grids in the three-dimensional space;

[0022] 4) According to the change of the analog value of the current signal of the range detector with time during the movement of the control rod the change of the analog value of the current signal of the total range detector with time R s (t) during the movement of the control rod is obtained.

[0023]

[0024] In the formula, J represents the total number of nodes in the axial direction of the range detector.

[0025] Preferably, the implementation process of step 3 is as follows:

[0026] 1) The basic principle of the reactivity instrument is the inverse point reactor equation, which can calculate the reactivity according to the current signal data of the range detector; therefore, the change of the analog value of the current signal of the total range detector with time R s (t) during the movement of the control rod is input into the inverse point reactor equation, and the change of the dynamic reactivity calculation value with time

[0027] 2) The dynamic reactivity calculation value when the control rod is located at the top of the reactor core is The dynamic reactivity calculation value when the control rod is located at the bottom of the reactor core is Then the control rod dynamic value calculation value introduced by the movement of the control rod from the top of the reactor core to the bottom of the reactor core is as follows:

[0028] Preferably,

[0029] The implementation process of step 4 is as follows:

[0030] The control rod dynamic value calculation value introduced by the movement of the control rod from the top of the reactor core to the bottom of the reactor core And the control rod static value calculation value introduced by the movement of the control rod from the top of the reactor core to the bottom of the reactor core The transient spatial factor TSF is calculated:

[0031]

[0032] Preferably, the implementation process of step 5 is as follows:

[0033] 1) In actual engineering applications, the current signal I(t) of the control rod during the movement of the dynamic rod marking process is recorded in real time by using each section power range detector j (t), j represents the number index of each section power range detector, and the current signal measured value I(t) of the total power range detector is calculated as shown in formula (6),

[0034]

[0035] 2) The current signal measured value I(t) of the total power range detector is input into the inverse point reactor equation, and the change of the dynamic reactivity measured value with time is obtained

[0036] 3) The dynamic reactivity measured value when the control rod is located at the top of the reactor core is The dynamic reactivity measured value when the control rod is located at the bottom of the reactor core is Then the control rod dynamic value measured value introduced by the movement of the control rod from the top of the reactor core to the bottom of the reactor core is As follows:

[0037]

[0038] 4) The transient spatial factor is applied to the control rod dynamic value measured value To obtain the control rod value measured value

[0039]

[0040] Compared with the prior art, the present application has the following advantages:

[0041] 1. The present application only needs to provide one transient spatial factor to complete the high-precision dynamic rod marking test, which saves the complicated data amount of the static correction factor and the dynamic correction factor required by the traditional dynamic rod marking method, and the implementation process is more convenient and fast, and has high engineering application value.

[0042] 2. The engineering implementation process of the present application only uses a power range detector and a reactivity instrument, does not need to make any changes to the current existing hardware facilities and systems, can directly apply the method of the present application, and has higher economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 A flow chart of the dynamic rod worth method based on the transient spatial factor of the present application;

[0044] Figure 2 An axial arrangement diagram of the power range detector;

[0045] Figure 3 A detailed flow chart of the transient spatial factor calculation. DETAILED DESCRIPTION

[0046] The present application will be further described in detail below in combination with the drawings and specific embodiments:

[0047] The present application corrects the measured value of the dynamic value of the control rod obtained by the reactivity instrument through the transient spatial factor, completes the measurement of the control rod value, and the specific steps are as shown in the figure, and include the following steps: Figure 1

[0048] Step 1: The steady-state numerical simulation calculation of the control rod located at the top and the bottom of the core is carried out by using the pressurized water reactor fuel management program, and the static value calculation value of the control rod is obtained. This step is mainly refined into the following parts:

[0049] 1) The steady-state neutron diffusion calculation of the state of the control rod located at the top of the core is carried out by using the pressurized water reactor fuel management program, and the static reactivity calculation value of the control rod located at the top of the core is obtained

[0050] 2) The steady-state neutron diffusion calculation of the state of the control rod located at the bottom of the core is carried out by using the pressurized water reactor fuel management program, and the static reactivity calculation value of the control rod located at the bottom of the core is obtained

[0051] 3) The static value calculation value of the control rod introduced by the movement of the control rod from the top of the core to the bottom of the core is calculated

[0052]

[0053] In this embodiment, the control rod is divided into 225 steps in the core axis, and the control rod is located at the bottom of the core as 0 step and at the top of the core as 225 step. However, in fact, the control rod will not be completely inserted to 0 step in the core, but will stop at the position of 5 steps, therefore, in the embodiment, 5 steps are taken as the bottom of the core.

[0054] ​Step 2: Based on the movement information of the control rods from the top to the bottom of the reactor core during the dynamic rod etching process, a transient numerical simulation calculation of the control rod movement process is performed using the pressurized water reactor fuel management program to obtain the time-varying simulated current signal value of the power range detector. This step is mainly detailed into the following parts:

[0055] 1) In pressurized water reactor (PWR) nuclear power plants, during the dynamic rod measurement method for control rods, the control rods move from the top to the bottom of the reactor core at a fixed drive speed. The PWR fuel management program is used to perform transient numerical simulations of the control rod movement from the top to the bottom of the core, obtaining the change in the three-dimensional power distribution P of the reactor core over time. k (t), where k represents the three-dimensional spatial grid number index and t represents time;

[0056] In this embodiment, the control rod moves at a speed of 72 steps per minute;

[0057] 2) Based on the core geometry and material arrangement, a core model is established, from the core fuel assemblies to the power range detectors. The power range detectors are divided into multiple sections along the axial direction. The response function ω of each power range detector section is calculated using the conjugate neutron transport equation. j,k , j represents the index of the power range detectors in each section, k represents the index of the three-dimensional spatial grid, and the response function of each power range detector characterizes the contribution of the three-dimensional power distribution of the core to the simulated value of the current signal of each power range detector.

[0058] 3) Based on the response function ω of each power range detector j,k The variation of the three-dimensional power distribution of the reactor core over time, Pk(t), during the movement of the control rods was used to calculate the variation of the simulated current signal of each power range detector over time during the movement of the control rods. 'S' stands for the abbreviation of the English word 'simulation'.

[0059]

[0060] In the formula: K represents the total number of grids in the three-dimensional space;

[0061] 4) Based on the change of the simulated current signal value of each power range detector over time during the movement of the control rod. The analog value of the current signal from the range detector changes over time (R) during the movement of the control rod. s (t),

[0062]

[0063] In the formula: J represents the total number of sections along the axis of the power range detector.

[0064] In this embodiment, the power range detector is divided into six sections in the axial direction, and is arranged as shown in Figure 2 .

[0065] Step 3: input the change of the current signal analog value of the power range detector in step 2 with time into the inverse point reactor equation, and calculate the control rod dynamic value calculation value introduced by the movement of the control rod from the top of the reactor core to the bottom of the reactor core; this step is mainly divided into the following parts:

[0066] 1) the basic principle of the reactivity instrument is the inverse point reactor equation, which can calculate the reactivity according to the current signal data of the power range detector. Therefore, the change of the total current signal analog value of the power range detector R s (t) in the movement of the control rod with time is input into the inverse point reactor equation, and the change of the dynamic reactivity calculation value with time

[0067] 2) the dynamic reactivity calculation value when the control rod is located at the top of the reactor core is the dynamic reactivity calculation value when the control rod is located at the bottom of the reactor core is and the control rod dynamic value calculation value introduced by the movement of the control rod from the top of the reactor core to the bottom of the reactor core is as follows:

[0068]

[0069] Step 4: calculate the transient spatial factor TSF according to the control rod dynamic value calculation value introduced by the movement of the control rod from the top of the reactor core to the bottom of the reactor core and the control rod static value calculation value introduced by the movement of the control rod from the top of the reactor core to the bottom of the reactor core

[0070]

[0071] The detailed calculation flowchart of the transient spatial factor TSF is shown in Figure 3 .

[0072] Step 5: in actual engineering application, the control rod dynamic value measured value is obtained according to the current signal recorded by the power range detector in real time and the inverse point reactor equation calculation of the reactivity instrument, and the control rod value measured value is finally obtained by applying the transient spatial factor in step 4. This step is mainly divided into the following parts:

[0073] 1) in actual engineering application, the current signal I j (t) of the control rod in the dynamic rod marking process is recorded in real time by each section of the power range detector, j represents the number index of each section of the power range detector, and the total current signal measured value I(t) is calculated as shown in formula (6),​

[0074]

[0075] 2) The current signal I(t) of the total power range detector is input into the inverse point reactor equation to obtain the dynamic reactivity measurement value over time

[0076] 3) The dynamic reactivity measurement value when the control rod is at the top of the core is The dynamic reactivity measurement value when the control rod is at the bottom of the core is The control rod dynamic value measurement value introduced by the movement of the control rod from the top of the core to the bottom of the core is As follows:

[0077]

[0078] 4) The transient spatial factor is applied to the control rod dynamic value measurement value The control rod value measurement value is obtained

[0079]

[0080] In this example, there are a total of 9 control rod groups, namely R, G1, G2, N1, N2, SA, SB, SC and SD, and the measurement results of the control rod value are shown in the following table.

[0081]

[0082] From the above results, it can be seen that the method of the present application can obtain a control rod value measurement result with high precision during dynamic rod marking, and has engineering application value.

Claims

1. A dynamic bar drawing method based on transient spatial factors, characterized by: The transient space factor of control rod value can be obtained according to theoretical calculation, and is applied to the dynamic rod marking process to realize the measurement of control rod value; the method comprises the following steps: Step 1: steady-state numerical simulation calculation is carried out on the control rod located at the top of the reactor core and the control rod located at the bottom of the reactor core by using a pressurized water reactor fuel management program to obtain a control rod static value calculation value; Step 2: according to the movement information of the control rod from the top of the reactor core to the bottom of the reactor core in the dynamic rod marking process, transient numerical simulation calculation is carried out on the movement process of the control rod by using the pressurized water reactor fuel management program to obtain the change of the current signal simulation value of the power range detector with time; Step 3: the change of the current signal simulation value of the power range detector with time in step 2 is input into the inverse point reactor equation to calculate the control rod dynamic value calculation value introduced by the movement process of the control rod from the top of the reactor core to the bottom of the reactor core; Step 4: according to the control rod static value calculation value in step 1 and the control rod dynamic value calculation value in step 3, a transient space factor is calculated; Step 5: in actual engineering application, the control rod dynamic value measured value is obtained according to the current signal recorded by the power range detector and the inverse point reactor equation calculation of the reactivity instrument, and the transient space factor in step 4 is applied to finally obtain the control rod value measured value; The implementation process of step 1 is as follows: 1) steady-state neutron diffusion calculation for the state when the control rods are located at the top of the core using a pressurized water reactor fuel management program to obtain a static reactivity calculation value for the state when the control rods are located at the top of the core 2) using a pressurized water reactor fuel management program to perform a steady-state neutron diffusion calculation for the state in which the control rods are at the bottom of the core, to obtain a static reactivity calculation value for the state in which the control rods are at the bottom of the core 3) Calculate the control rod static worth calculation value introduced by the movement of the control rods from the top of the core to the bottom of the core The implementation process of step 2 is as follows: 1) In the process of measuring the control rod worth by dynamic rod worth method, the control rod moves from the top of the core to the bottom of the core at a fixed drive speed, and the transient numerical simulation calculation of the movement of the control rod from the top of the core to the bottom of the core is carried out by using the pressurized water reactor fuel management program, and the change of the three-dimensional power distribution of the core with time P k (t), k represents the three-dimensional space grid number index, and t represents time; 2) According to the geometry and material arrangement of the reactor core, a reactor core model from the reactor core fuel assembly to the power range probe is established, the power range probe is divided into multiple sections in the axial direction, and the response function ω of each section of the power range probe is obtained by calculating the conjugate neutron transport equation j,k , j represents the number index of each section of the power range probe, k represents the three-dimensional space grid number index, and the response function of each section of the power range probe represents the contribution of the three-dimensional power distribution of the reactor core to the simulated value of the current signal of each section of the power range probe. 3) The response function ω of the range detector of each section j,k The simulation value of the current signal of the range detector of each section during the movement of the control rod is calculated according to the response function ω of the range detector of each section and the change Pk(t) of the three-dimensional power distribution of the core with time during the movement of the control rod s represents the abbreviation of simulation in English, In the formula, K represents the total number of three-dimensional space grids; 4) The change in time of the analog value of the current signal of the power range detector of the total power range during the movement of the control rods obtaining the change in time of the analog value of the current signal of the power range detector of the total power range during the movement of the control rods s (t), In the formula, J represents the total number of axial nodes of the power range detector; The implementation process of step 3 is as follows: 1) The basic principle of the reactivity instrument is the inverse point reactor equation, which can calculate the reactivity according to the current signal data of the power range detector; therefore, the change of the total power range detector current signal simulation value with time R s (t) is input into the inverse point reactor equation to calculate the change of the dynamic reactivity calculation value with time 2) the calculated value of the dynamic reactivity when the control rod is at the top of the core is the calculated value of the dynamic reactivity when the control rod is at the bottom of the core is the calculated value of the dynamic value of the control rod introduced by the movement of the control rod from the top of the core to the bottom of the core is as follows: The implementation process of step 4 is as follows: a control rod dynamic worth calculated value introduced in accordance with movement of the control rod from the top of the core to the bottom of the core and a control rod static worth calculated value introduced in accordance with movement of the control rod from the top of the core to the bottom of the core calculating a transient spatial factor TSF: The implementation process of step 5 is as follows: 1) In practical engineering applications, the current signal I of the power range detector is recorded in real time when the dynamic rod moves j (t), j represents the number index of each power range detector, and the measured value of the current signal I(t) of the total power range detector is calculated as shown in equation (6). 2) The current signal I(t) of the total power range probe is input into the inverse point reactor equation to obtain the dynamic reactivity signal change with time 3) the measured value of the dynamic reactivity when the control rod is at the top of the core is the measured value of the dynamic reactivity when the control rod is at the bottom of the core is the measured value of the dynamic value introduced by the movement of the control rod from the top of the core to the bottom of the core is as follows: 4) Apply transient spatial factors to the control rod dynamic worth measured values Obtain control rod worth measured values

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