A method for measuring the differential value of boron based on the process of critical dilution
By utilizing source range detector counting data and core calculation software during the critical dilution process of a pressurized water reactor, accurate measurement of the differential boron value in nuclear power plants was achieved, solving the problem of boron concentration measurement error after refueling overhaul and ensuring the accuracy of the control rod full-lift status.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XI AN JIAOTONG UNIV
- Filing Date
- 2023-07-07
- Publication Date
- 2026-05-29
AI Technical Summary
The lack of boron differential value measurement after refueling overhauls in nuclear power plants leads to errors in the measurement results of critical boron concentration under full control rod conditions, and existing technologies cannot accurately measure the boron differential value.
By utilizing source range detector counting data during the critical dilution process of a pressurized water reactor, combined with core calculation software for simulation calculation and actual value processing, the boron differential value can be measured. This includes real-time monitoring and signal processing of source range detector counting data during the subcritical dilution process, ensuring measurement accuracy.
Without requiring additional hardware modifications, it provides more accurate critical boron concentration measurement results for the entire rod lifting state, reduces measurement errors, and meets engineering acceptance criteria.
Smart Images
Figure CN116864163B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of physical calculation technology for pressurized water reactor cores, specifically to a method for measuring the differential value of boron based on the critical dilution process. Background Technology
[0002] After a major overhaul and refueling, commercial nuclear power plants need to measure the critical boron concentration in the fully raised control rod state and compare it with the critical boron concentration in the design report for verification. However, in actual measurement, the control rods are not actually moved to the fully raised state to measure the critical boron concentration. Instead, the R rod is moved to a critical position, and the value of compensating for the R rod insertion into the core is calculated using the boron concentration, which is then used to calculate the critical boron concentration in the fully raised control rod state. When calculating the compensation value using boron concentration, the differential boron value is required. However, current tests after refueling and overhauls in nuclear power plants do not measure the differential boron value; instead, the results calculated directly by the core program are used. Therefore, it is difficult to guarantee that the program calculation results are completely consistent with the actual differential boron value. Thus, the lack of tests on the differential boron value after refueling and overhauls in nuclear power plants leads to a certain degree of error in the measurement results of the critical boron concentration in the fully raised control rod state. Summary of the Invention
[0003] To address the current lack of boron differential value measurement in nuclear power plants, this invention aims to provide a boron differential value measurement method based on the criticality dilution process. This method utilizes source range detector counting data from the subcritical dilution process to measure the boron differential value, ensuring the accuracy of the critical boron concentration at the full control rod lift stage. Furthermore, it allows for comparison and verification with the boron differential value calculated by the core program.
[0004] To achieve the above objectives, the present invention adopts the following technical solution:
[0005] A method for measuring the differential value of boron based on the criticality dilution process can measure the differential value of boron according to the measured values of source range detector counts during the criticality dilution process of a pressurized water reactor; the method includes the following steps:
[0006] Step 1: Based on the boron concentration and control rod position information during the critical dilution process, subcritical simulation calculations are performed using core calculation software to obtain the calculated values of the source range detector count multiplication factor and the core reactivity at the initial moment of the dilution process.
[0007] Step 2: Based on the measured value of the source range detector count at the initial moment of the critical dilution process, obtain the measured value of the source range detector count proliferation factor at the initial moment of the dilution process.
[0008] Step 3: Based on the calculated value of the source range detector count multiplication factor and the calculated value of the core reactivity at the initial moment of the dilution process in Step 1, and the measured value of the source range detector count multiplication factor at the initial moment of the dilution process in Step 2, obtain the measured value of the core reactivity at the initial moment of the dilution process.
[0009] Step 4: Combine the changes in boron concentration at the initial and final dilution times with the measured reactivity at the initial dilution time in Step 3 to calculate the measured value of the boron differential value, thus realizing the measurement of the control rod value.
[0010] The implementation process of step 1 is as follows:
[0011] 1) During the criticality dilution process, the control rod position of the pressurized water reactor nuclear power plant is kept constant. Water is gradually injected into the primary loop of the pressurized water reactor nuclear power plant to dilute the boron concentration in the primary loop, so that the pressurized water reactor gradually changes towards the critical state. The initial and final moments of the dilution process are selected as the boron differential value measurement points, and the boron concentration information and control rod position information at the initial and final moments are recorded.
[0012] 2) Based on the boron concentration at the beginning and end of the dilution process and the control rod position information, neutronics simulation calculations were performed using core calculation software to solve the fixed neutron source equation and eigenvalue equation respectively.
[0013] 3) Based on the neutronics simulation results from the core computing software, the calculated value of the source range detector count at the initial moment of the dilution process is obtained. Calculated reactivity of the reactor core at the initial moment of the dilution process Calculated value of the source range detector count at the end of the dilution process And the calculated reactivity of the core at the end of the dilution process.
[0014] 4) Calculate the source range detector count multiplication factor at the initial moment of the dilution process according to formula (1).
[0015]
[0016] The implementation process of step 2 is as follows:
[0017] 1) During the criticality dilution process, pressurized water reactor nuclear power plants use source range detectors to monitor the reactor core status in real time, ensuring that changes in the core status remain within the safe operating range, and recording the measured value M1 of the source range detector count at the initial moment of the criticality dilution process. m The measured value M2 of the source range detector count at the end time. m ;
[0018] The measured value M1 of the source range detector count at the initial moment of the critical dilution process. m The measured value M2 of the source range detector count at the end time. m Due to noise, there are large signal fluctuations. Directly using these methods will lead to large and uncontrollable errors in the measurement results. Therefore, the following two methods are used to obtain accurate measured values of the source range detector count:
[0019] Method 1: The measured values of the source range detector count at the initial and final moments of the critical dilution process are processed using a noise reduction method to obtain relatively accurate measured values of the source range detector count, thus ensuring the accuracy of boron differential value measurement.
[0020] Method 2: Within a certain period near the initial moment of the dilution process, there exists a time interval during which neither the control rod nor the boron concentration changes. The average value of the measured source range detector counts during this period is calculated and used as the measured source range detector count value M1 at the initial moment of the dilution process. m Near the end of the dilution process, there is a period where neither the control rod nor the boron concentration changes. The average of the measured source range detector counts during this period is used as the measured source range detector count M2 at the end of the dilution process. m .
[0021] 2) Obtain the measured value of the source range detector count proliferation factor at the initial moment of the dilution process according to formula (2).
[0022]
[0023] The implementation process of step 3 is as follows:
[0024] The calculated value of the proliferation factor Q is based on the source range detector count at the initial moment of the dilution process. c 1. Calculated reactivity of the reactor core at the initial moment of the dilution process And the measured value of the source range detector count proliferation factor at the initial moment of the dilution process. The measured reactivity of the reactor core at the initial moment of the dilution process was obtained using formula (3).
[0025]
[0026] The implementation process of step 4 is as follows:
[0027] 1) Based on the boron concentration B1 at the beginning of the dilution process and the boron concentration B2 at the end of the dilution process, obtain the boron concentration change ΔB during the dilution process;
[0028] ΔB=B2-B1 (Formula 4)
[0029] 2) Calculated reactivity of the reactor core at the end of the dilution process Measured values of core reactivity at the initial moment of the dilution process The boron concentration change ΔB during the dilution process was used to calculate the measured value of the differential boron value, as shown in formula (5).
[0030]
[0031] Compared with the prior art, the present invention has the following advantages:
[0032] 1. The core criticality dilution process used in this invention is an existing criticality operation procedure after refueling in nuclear power plants. No additional operation procedures are required. Furthermore, the source range detector counting data in this process already exists and is used to monitor the real-time status of the core. Therefore, no hardware modifications or operations are required for the method of this invention based on existing nuclear power plant facilities.
[0033] 2. This invention completes the boron differential value measurement during the core critical dilution process, which solves the shortcoming of not conducting boron differential value tests during the start-up physical test, and can obtain a more accurate critical boron concentration in the full-rod state. Attached Figure Description
[0034] Figure 1 This is a flowchart for a method to measure the differential value of boron based on the critical dilution process.
[0035] Figure 2 The radial arrangement of the source range detector. Detailed Implementation
[0036] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:
[0037] This invention achieves boron differential value measurement using source range detector counting data from the subcritical dilution process. Specific steps are as follows: Figure 1 As shown, it includes the following steps:
[0038] Step 1: Based on the boron concentration and control rod position information during the critical dilution process, subcritical simulation calculations are performed using core calculation software to obtain the calculated values of the source range detector count multiplication factor and the core reactivity at the initial moment of the dilution process. This step is mainly detailed into the following parts:
[0039] 1) During the criticality dilution process, the control rod position of the pressurized water reactor nuclear power plant is kept constant. Water is gradually injected into the primary loop of the pressurized water reactor nuclear power plant to dilute the boron concentration in the primary loop, so that the pressurized water reactor gradually changes towards the critical state. The initial and final moments of the dilution process are selected as the boron differential value measurement points, and the boron concentration information and control rod position information at the initial and final moments are recorded.
[0040] In this example, the control rod position during the dilution process is R rod at step 150, while the other rod groups are all in the fully lifted state at the top of the core.
[0041] 2) Based on the boron concentration at the beginning and end of the dilution process and the control rod position information, neutronics simulation calculations were performed using core calculation software to solve the fixed neutron source equation and eigenvalue equation respectively.
[0042] 3) Based on the neutronics simulation results from the core computing software, the calculated value of the source range detector count at the initial moment of the dilution process is obtained. Calculated reactivity of the reactor core at the initial moment of the dilution process Calculated value of the source range detector count at the end of the dilution process And the calculated reactivity of the core at the end of the dilution process.
[0043] In this example, the radial position of the source range detector is as follows: Figure 2 As shown, it includes two source range detectors, located on the left and right sides of the pressurized water reactor core, respectively, and outside the insulation layer, about 15cm away from the insulation layer.
[0044] 4) Calculate the calculated value Q of the source range detector count proliferation factor at the initial moment of the dilution process according to formula (1). c 1.
[0045]
[0046] Step 2: Based on the measured source range detector count at the initial moment of the critical dilution process, obtain the measured value of the source range detector count growth factor at the initial moment of the dilution process. This step is mainly broken down into the following parts:
[0047] 1) During the criticality dilution process, pressurized water reactor nuclear power plants use source range detectors to monitor the reactor core status in real time, ensuring that changes in the core status remain within the safe operating range, and recording the measured value M1 of the source range detector count at the initial moment of the criticality dilution process. m The measured value M2 of the source range detector count at the end time. m ;
[0048] 2) The measured values of the source range detector count at the beginning and end of the dilution process are subject to large signal fluctuations due to noise. Directly using these values will result in large and uncontrollable measurement errors. Therefore, two methods can be used to obtain accurate measured values of the source range detector count.
[0049] Method 1: The measured values of the source range detector count at the initial and final moments of the critical dilution process are processed using a noise reduction method to obtain relatively accurate measured values of the source range detector count, thus ensuring the accuracy of boron differential value measurement.
[0050] Method 2: Within a certain period near the initial moment of the dilution process, there exists a time interval during which neither the control rod nor the boron concentration changes. The average value of the measured source range detector counts during this period is calculated and used as the measured source range detector count value M1 at the initial moment of the dilution process. m Near the end of the dilution process, there is a period where neither the control rod nor the boron concentration changes. The average of the measured source range detector counts during this period is used as the measured source range detector count M2 at the end of the dilution process. m .
[0051] In this embodiment, the measured value M1 of the source range detector count at the initial moment of the dilution process is... m =2320, the measured value M2 of the source range detector count at the end of the dilution process. m =10439.
[0052] 3) Obtain the measured value of the source range external detector count multiplication factor at the initial moment of the dilution process according to formula (2).
[0053]
[0054] Step 3: Calculate the source range detector count proliferation factor based on the value obtained in Step 1 at the initial moment of the dilution process. Calculated reactivity of the reactor core at the initial moment of the dilution process And the measured value of the source range detector count proliferation factor at the initial moment of the dilution process obtained in step 2. The measured reactivity of the reactor core at the initial moment of the dilution process was obtained using formula (3).
[0055]
[0056] Step 4: Based on the boron concentration B1 at the beginning of the dilution process and the boron concentration B2 at the end of the dilution process, obtain the boron concentration change ΔB during the dilution process;
[0057] ΔB=B2-B1 (Formula 4)
[0058] Based on the reactivity calculation value of the core at the end of the dilution process Measured values of core reactivity at the initial moment of the dilution process The boron concentration change ΔB during the dilution process is used to calculate the measured value DBC of the boron differential value, as shown in formula (5).
[0059]
[0060] In this embodiment, the comparison between the measured value and the theoretical calculated value of boron differential value is shown in the table below.
[0061] Theoretical calculation value Measured values Boron differential value (pcm / ppm) -6.709 -6.364 Error (pcm / ppm) — 0.345
[0062] The results show that the error between the boron differential value measured by the method of this invention and the theoretical calculation value is very small, only 0.345 pcm / ppm, which meets the engineering acceptance criteria and has engineering application value.
Claims
1. A method for measuring the differential value of boron based on the critical dilution process, characterized in that: The boron differential value can be measured based on the source range detector counts during the critical dilution process of a pressurized water reactor; this includes the following steps: Step 1: Based on the boron concentration and control rod position information during the critical dilution process, subcritical simulation calculations are performed using core calculation software to obtain the calculated values of the source range detector count multiplication factor and the core reactivity at the initial moment of the dilution process. Step 2: Based on the measured value of the source range detector count at the initial moment of the critical dilution process, obtain the measured value of the source range detector count proliferation factor at the initial moment of the dilution process. Step 3: Based on the calculated value of the source range detector count multiplication factor and the calculated value of the core reactivity at the initial moment of the dilution process in Step 1, and the measured value of the source range detector count multiplication factor at the initial moment of the dilution process in Step 2, obtain the measured value of the core reactivity at the initial moment of the dilution process. Step 4: Combine the changes in boron concentration at the initial and final dilution times with the measured reactivity at the initial dilution time in Step 3 to calculate the measured value of the boron differential value, thereby realizing the measurement of the control rod value. The implementation process of step 1 is as follows: 1) During the criticality dilution process, the control rod position of the pressurized water reactor nuclear power plant is kept constant. Water is gradually injected into the primary loop of the pressurized water reactor nuclear power plant to dilute the boron concentration in the primary loop, so that the pressurized water reactor gradually changes towards the critical state. The initial and final moments of the dilution process are selected as the boron differential value measurement points, and the boron concentration information and control rod position information at the initial and final moments are recorded. 2) Based on the boron concentration at the beginning and end of the dilution process and the control rod position information, neutronics simulation calculations were performed using core calculation software to solve the fixed neutron source equation and eigenvalue equation respectively. 3) Based on the neutronics simulation results from the core computing software, the calculated value of the source range detector count at the initial moment of the dilution process is obtained. Calculated reactivity of the reactor core at the initial moment of the dilution process Calculated value of the source range detector count at the end of the dilution process And the calculated reactivity of the core at the end of the dilution process. ; 4) Calculate the source range detector count multiplication factor at the initial moment of the dilution process according to formula (1). ; Official (1).
2. The method according to claim 1, characterized in that: The implementation process of step 2 is as follows: 1) During the criticality dilution process, pressurized water reactor nuclear power plants use source range detectors to monitor the reactor core status in real time, ensuring that changes in the core status remain within the safe operating range, and recording the measured values of the source range detector counts at the initial moment of the criticality dilution process. Measured source range detector count at the end time ; 2) Obtain the measured value of the source range detector count proliferation factor at the initial moment of the dilution process according to formula (2). ; Official (2).
3. The method according to claim 2, characterized in that: The measured value of the source range detector count at the initial moment of the critical dilution process described in step 1). Measured source range detector count at the end time Due to noise, there are large signal fluctuations. Directly using these methods will lead to large and uncontrollable errors in the measurement results. Therefore, the following two methods are used to obtain accurate measured values of the source range detector count: Method 1: The measured values of the source range detector count at the initial and final moments of the critical dilution process are processed using a noise reduction method to obtain relatively accurate measured values of the source range detector count, thus ensuring the accuracy of boron differential value measurement. Method 2: Within a certain period near the initial moment of the dilution process, there exists a time interval during which neither the control rod nor the boron concentration changes. The average value of the measured source range detector counts during this period is calculated and used as the measured source range detector count at the initial moment of the dilution process. Near the end of the dilution process, there is a period where neither the control rod nor the boron concentration changes. The average of the measured source range detector counts during this period is used as the measured source range detector count at the end of the dilution process. .
4. The method according to claim 1, characterized in that: The implementation process of step 3 is as follows: The calculated value of the proliferation factor was obtained from the source range detector count at the initial moment of the dilution process. Calculated reactivity of the reactor core at the initial moment of the dilution process And the measured value of the source range detector count proliferation factor at the initial moment of the dilution process. The measured values of the reactivity of the reactor core at the initial moment of the dilution process were obtained using formula (3). ; Official (3).
5. The method according to claim 1, characterized in that: The implementation process of step 4 is as follows: 1) Based on the boron concentration at the initial moment of the dilution process B 1. Boron concentration at the end of the dilution process B 2. Obtain the boron concentration change Δ during the dilution process. B ; Official (4) 2) Calculated reactivity of the reactor core at the end of the dilution process Measured reactivity of the reactor core at the initial moment of the dilution process and the change in boron concentration Δ during the dilution process B The measured value of the differential value of boron is calculated as shown in formula (5); Official (5).