Judgment method for inert flow test of nuclear reactor coolant pump

Abstract

The invention relates to a method for judging an inert flow test of a coolant pump of a nuclear reactor. The method comprises the following steps of: 1, collecting flows of three loops and rotating speeds of the coolant pump of the reactor of the three loops; 2, stopping all reactor coolant pumps at the same time; 3, recording the flows and the pump rotating speeds of the three loops at different moments by taking simultaneous shutdown of the three reactor coolant pumps as a zero moment; 4, calculating the reactor coolant flow test report recording condition according to heat balance, wherein the three loop flows are Q1, Q2 and Q3 respectively when the last fuel circulation reactor coolant system operates stably; 5, preliminarily judging whether the flow of each loop meets the requirement or not; 6, preliminarily judging whether the total flow of the coolant in the core of the primary-loop reactor meets the requirement or not; seventhly, the rotation speed drop of each loop pump is compared with a design curve; and 8, finally determining a test result. The method is used for judging whether the inert flow test of the second-generation pressurized water reactor coolant pump or the second-generation pressurized water reactor coolant pump is qualified or not.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of nuclear reactor coolant pump inert flow test determination method, it is applied to M310 and CPR1000 etc. Generation or generation plus type pressurized water reactor, for determining whether reactor coolant pump inert flow test is qualified, i.e. whether the inert rotation performance of pump itself can satisfy nuclear safety requirement after pump sudden power loss. BACKGROUND

[0002] The purpose of the safety-related periodic test "reactor coolant pump inert flow test" is to verify whether the NSSS can remain in a safe state before reaching the minimum DNBR after the total loss of reactor coolant forced circulation flow. The periodic test is carried out on the hot shutdown platform during each major overhaul and startup of the unit. For generation or generation plus units such as M310 units, CPR1000 units, etc., the determination method of this test is to measure the flow data of each loop using the reactor primary loop flow meter. The flow meter measures percentage values, and the actual flow data is obtained by bringing the flow of each loop calculated from the annual primary loop temperature test using primary and secondary loop heat balance into the percentage flow meter. Finally, it is compared with the nuclear safety criteria to confirm whether the test is qualified.

[0003] This method for generation or generation plus units such as M310 units, CPR1000 units, etc. Since the flow meter of each loop of the primary loop is a bend flow meter, and the display value is a percentage, this flow meter is mainly used for reference and indication when measuring the flow of the reactor primary loop coolant. Its measurement accuracy is not high. Moreover, for this flow meter, after the loss of power supply of three reactor coolant pumps, the pressure of the primary loop will fluctuate severely, which will cause the differential pressure measured by the bend flow meter to have great uncertainty and display delay. This will cause the flow meter to show that the flow is still rising or irregularly fluctuating after the reactor coolant pump has returned to the shutdown signal. According to experience, the whole process lasts about 0.5s. This has already affected the judgment of whether the test is qualified or not.

[0004] In summary, due to the design of generation or generation plus units such as M310 units, CPR1000 units, etc., the original determination method of reactor coolant pump inert flow test has many shortcomings such as inaccuracy, delayed response of flow meter, abnormal fluctuation, poor implementability, etc. Therefore, it is urgent to develop a more accurate, intuitive, simple and safe (without additional equipment affecting nuclear safety) test determination method. SUMMARY

[0005] The application aims to provide a determination method for the inert flow test of a nuclear reactor coolant pump, which can solve the problems in the determination process of the test for the second generation or second generation plus nuclear power unit under the premise of ensuring the safe and stable operation of the unit and the accuracy of the determination.

[0006] To achieve the above-mentioned purpose, the technical solution adopted by the application is as follows:

[0007] A determination method for the inert flow test of a nuclear reactor coolant pump, when the primary loop reactor coolant system has three loops, comprising the following steps:

[0008] Step one: collecting the flow of the three loops and the rotation speed of the three loop reactor coolant pumps;

[0009] Step two: simultaneously stopping all the reactor coolant pumps;

[0010] Step three: taking the simultaneous stop of the three reactor coolant pumps as the zero time, and recording the flow and pump rotation speed of the three loops at different time;

[0011] Step four: calculating the reactor coolant flow test report according to the heat balance, and recording the flow of the three loops as Q1, Q2 and Q3 when the reactor coolant system is stably operated in the last fuel cycle;

[0012] Step five: preliminarily determining whether the flow of each loop meets the requirements;

[0013] Step six: preliminarily determining whether the total flow of the primary loop reactor core coolant meets the requirements;

[0014] Step seven: comparing the rotation speed of the pump of each loop with the design curve;

[0015] Step eight: finally determining the test result.

[0016] Step three: collecting a group of data every 0.1s.

[0017] Step five: the preliminary determination method is that the reactor coolant pump inert flow test requires that the minimum flow of each loop after stopping the pump for 4s cannot be lower than the flow Q 准则t = 4.0, the uncertainty of the rotation speed measuring instrument together with the instrument channel is η, and the corresponding rotation speed Δn = η × n 额定 , n 额定 is the rated flow of the three loop reactor coolant pumps, and whether the flow of each loop meets the test criteria requirements is determined according to the following formula:

[0018]

[0019] Q 1t = 4.0 is the flow of each loop at 4.0s after stopping the pump, n 1t＝4.0n is the pump speed at 4.0s after the pump is stopped for the first loop 1t＝0.0 n is the pump speed at 0s after the pump is stopped for the first loop, such as Q 1t Q 准则t = 4.0, it is considered that the flow of the first loop preliminarily meets the requirements, otherwise it does not meet the requirements; for the second loop:

[0020]

[0021] Q 2t n is the flow of the second loop at 4.0s after the pump is stopped 2t＝4.0 n is the pump speed at 4.0s after the pump is stopped for the second loop 2t＝0.0 n is the pump speed at 0s after the pump is stopped for the second loop, such as Q 2t Q 准则t = 4.0, it is considered that the flow of the second loop preliminarily meets the requirements, otherwise it does not meet the requirements; for the third loop:

[0022]

[0023] Q 3t n is the flow of the third loop at 4.0s after the pump is stopped 3t＝4.0 n is the pump speed at 4.0s after the pump is stopped for the third loop 3t＝0.0 n is the pump speed at 0s after the pump is stopped for the third loop, such as Q 3t Q 准则t = 4.0, it is considered that the flow of the third loop preliminarily meets the requirements, otherwise it does not meet the requirements.

[0024] Step six: according to step five, the flow at 4.1s after the pump is stopped for each loop is calculated, the first loop is:

[0025]

[0026] Q 1t n is the flow of the first loop at 4.1s after the pump is stopped 1t＝4.1 n is the pump speed at 4.1s after the pump is stopped for the first loop

[0027] The second loop is:

[0028]

[0029] Q 2t n is the flow of the second loop at 4.1s after the pump is stopped 2t＝4.1 n is the pump speed at 4.1s after the pump is stopped for the second loop

[0030] The third loop is:

[0031]

[0032] Q3t = 4.1 is the flow rate of the three loops at the time of pump stop 4.1 s, n 3t＝4.1 = 4.1 is the pump speed at the time of 4.1 s after the pump is stopped, the reactor coolant pump inertia flow test requires that the core flow rate cannot be lower than the flow rate Q 准则t = 4.1, then the following comparison is made:

[0033] Q1t = 4.1 + Q2t = 4.1 + Q3t = 4.1 > Q 准则t = 4.1

[0034] If the above formula is met, it is considered that the total core flow rate preliminarily meets the requirements.

[0035] Step seven: According to the requirements of the upstream file, the evaluation requirements of the speed drop curve in the reactor primary coolant pump inertia flow test are as follows: the speed ratio:

[0036]

[0037] By analogy:

[0038] In the formula, Ω 1t represents the speed ratio of the pump at time t of the loop, n 1t is the pump speed at time t after the pump is stopped;

[0039] If there is:

[0040] Ω 1t＝0.0 ≥ Ω 曲线t＝0.0

[0041] Ω 1t＝0.5 ≥ Ω 曲线t＝0.5

[0042] Ω 1t＝1.0 ≥ Ω 曲线t＝1.0

[0043] By analogy Ω 1t＝5.0 ≥ Ω 曲线t＝5.0

[0044] In the formula, Ω 曲线t represents the speed ratio of the pump at time t of each loop; it is considered that the pump speed drop meets the curve, and if there is a group that does not meet the above, it is considered that the pump speed drop does not meet the curve.

[0045] Both the two-loop and the three-loop are calculated and compared in the manner of the one-loop.

[0046] Step eight: According to steps five to seven, if all the requirements are met, it is considered that the test is preliminarily qualified, and subsequent unit power-up operation is carried out, and after the unit reaches full power again, the reactor coolant flow test is re-executed according to the heat balance calculation, and the measured reactor coolant system three-loop flow rate Q1n , Q 2n , Q 3n respectively replace Q1, Q2, Q3 in step five and step six, if the comparison of step five and step six still meets the requirements, it is considered that the test finally meets the requirements, and the test is qualified.

[0047] Step eight: if any loop flow or total flow in step five or step six does not meet the requirements, it is considered that the test is unqualified.

[0048] Step eight: if the flow in step five or step six meets the requirements, but any one group of data or multiple data in step seven does not meet the requirements, it is initially considered that the test is qualified, but has defects, and the nuclear power unit is re-powered to full power, and the test of calculating the reactor coolant flow according to the heat balance is re-executed, and the three loop flows Q 1n , Q 2n , Q 3n respectively replace Q1, Q2, Q3 in step five and step six, if the comparison of step five and step six still meets the requirements, it is considered that the test flow meets the requirements, and the test is qualified, but has defects.

[0049] The beneficial effects obtained by the present application are:

[0050] The present application combines the accuracy of on-site actual instrument measurement, the execution method of related tests of domestic third-generation nuclear power units, and the judgment principle of the original method, and comprehensively formulates a more accurate, more convenient, and more secure test judgment method for the unit, which can ensure the nuclear safety of the unit to a greater extent and ensure the stable operation of the unit.

[0051] The present application can more accurately determine whether the reactor coolant pump inertial flow test meets the requirements, which is consistent with the original intention of the design in principle, is more convenient in data acquisition, zero point determination and calculation evaluation from the implementation level, is more conservative compared with the original method, and does not introduce more nuclear safety risks; compared with the original method, the present application is more scientific, adopts different reactor primary coolant system flow data for verification twice, and is more secure. DETAILED DESCRIPTION

[0052] The present application will be described in detail below in combination with specific embodiments.

[0053] A judgment method for a nuclear reactor coolant pump inertial flow test, comprising the following steps:

[0054] When the primary reactor coolant system has three loops:

[0055] Step one: data collection setting: set the data collection points in advance in the unit test data collection system, and the collected data includes: the flow of three loops, the speed of three loop reactor coolant pumps. There are three coolant pumps in three loops, and two coolant pumps in two loops.

[0056] Step two: stop all reactor coolant pumps at the same time: the unit is in the post-refueling maintenance start-up hot shutdown condition, and all reactor coolant pumps of the unit are stopped at the same time according to the method required by the test upstream file. There are three coolant pumps in three loops, and two coolant pumps in two loops.

[0057] Step three: data collection: collect a group of data every 0.1s, and take the simultaneous stop of three reactor coolant pumps as the zero time. Record the flow and pump speed data of the corresponding three loops at different times. Here, the letters represent as follows: the flow of 1 loop at 0.5s after the pump is set as Q 1t =0.5; similarly, the flow of 3 loop at 1.2s after the pump is set as Q 3t =1.2; the pump speed of 2 loop at 0.4s after the pump is set as n 2t＝0.4 ; similarly, the pump speed of 3 loop at 4.2s after the pump is set as n 3t＝4.2 . The relevant letters in the following are expressed in this rule.

[0058] Step four: initial flow: according to the record of the reactor coolant flow test report calculated by the heat balance, the flow of three loops during the stable operation of the reactor coolant system in the last fuel cycle is Q1, Q2 and Q3 respectively.

[0059] Step five: preliminary judgment of whether the flow of each loop meets the requirements: according to the safety criteria of the reactor coolant system, the reactor coolant pump inertia flow test requires that the minimum flow of each loop after the pump is stopped for 4s cannot be lower than Q 准则t =4.0. Then the corresponding conditions of each loop are as follows:

[0060]

[0061]

[0062] The uncertainty of the speed measuring instrument together with the instrument channel is η, then the corresponding speed Δn is: Δn=η×n 额定 Note: n 额定 is the rated flow of the three loop reactor coolant pumps.

[0063] Then whether the flow of one loop meets the test criteria requirements is judged according to the following formula:

[0064]

[0065] In the formula, Q1t = 4.0 is the flow rate of the primary loop at 4.0 s after the pump is stopped, n 1t＝4.0 is the pump speed at 4 s after the primary loop pump is stopped, n 1t＝0.0 is the pump speed at 0 s after the primary loop pump is stopped, such as Q 1t = 4.0 > Q 准则t = 4.0, it is considered that the primary loop flow rate preliminarily meets the requirement, otherwise it does not meet the requirement; similarly for the secondary loop:

[0066]

[0067] Q = 4.1 is the flow rate of the secondary loop at 4.1 s after the pump is stopped, n 2t = 4.0 is the flow rate of the primary loop at 4.0 s after the pump is stopped, n 2t＝4.0 is the pump speed at 4 s after the secondary loop pump is stopped, n 2t＝0.0 is the pump speed at 0 s after the secondary loop pump is stopped, such as Q 2t = 4.0 > Q 准则t = 4.0, it is considered that the secondary loop flow rate preliminarily meets the requirement, otherwise it does not meet the requirement; similarly for the tertiary loop:

[0068]

[0069] Q = 4.1 is the flow rate of the secondary loop at 4.1 s after the pump is stopped, n 3t = 4.0 is the flow rate of the primary loop at 4.0 s after the pump is stopped, n 3t＝4.0 is the pump speed at 4 s after the tertiary loop pump is stopped, n 3t＝0.0 is the pump speed at 0 s after the tertiary loop pump is stopped, such as Q 3t = 4.0 > Q 准则t = 4.0, it is considered that the tertiary loop flow rate preliminarily meets the requirement, otherwise it does not meet the requirement.

[0070] Step six: preliminary determination of whether the total flow rate of the primary loop reactor core coolant meets the requirement:

[0071] According to the calculation method of step five, the flow rate of each loop at 4.1 s after the pump is stopped is calculated, and the primary loop is:

[0072]

[0073] Q = 4.1 is the flow rate of the primary loop at 4.1 s after the pump is stopped, n 1t = 4.0 is the flow rate of the primary loop at 4.0 s after the pump is stopped, n 1t＝4.1 is the pump speed at 4.1 s after the primary loop pump is stopped; the secondary loop is:

[0074]

[0075] Q = 4.1 is the flow rate of the secondary loop at 4.1 s after the pump is stopped, n 2t = 4.0 is the flow rate of the primary loop at 4.0 s after the pump is stopped, n2t＝4.1 The pump speed is 4.1 seconds after the pump stops on the second ring road; for the third ring road:

[0076]

[0077] In the formula Q 3t =4.1 represents the flow rate of the reactor coolant system's three-loop circuit at 4.1 seconds after pump shutdown, n 3t＝4.1 The pump speed is 4.1 seconds after the three-loop pump is shut down. The reactor coolant pump inertial flow test requires that the core flow rate must not be lower than the flow rate Q 4.1 seconds after the pump is shut down. 准则t =4.1. Then the following comparison is possible:

[0078] Q1t=4.1+Q2t=4.1+Q3t=4.1>Q 准则t =4.1

[0079] If the above formula is satisfied, the total core flow rate is considered to have initially met the requirements.

[0080] Step 7: Compare the speed drop of each loop pump with the design curve.

[0081] According to upstream documentation, the reactor primary coolant pump inertial flow test includes an evaluation of the speed drop curve, and the evaluation requires the following curve:

[0082] Time after pump stop Speed ratio of each loop pump (curve) 0.0 Ω 曲线t＝0.0 ]]> 0.5 Ω 曲线t＝0.5 ]]> 1.0 Ω 曲线t＝1.0 ]]> 1.5 Ω 曲线t＝1.5 ]]> ...... ...... 4.5 Ω 曲线t＝4.5 ]]> 5.0 Ω 曲线t＝5.0 ]]>

[0083] The pump speed ratio at different times in each loop is expressed as follows (taking one loop as an example):

[0084]

[0085]

[0086] Speed ​​ratios in the table above:

[0087]

[0088] And so on.

[0089]

[0090] In the formula Ω 1t n represents the pump speed ratio at time t in the loop. 1t The pump speed at time t after the pump in the loop stops;

[0091] If:

[0092] Ω 1t＝0.0 ≥Ω 曲线t＝0.0

[0093] Ω 1t＝0.5 ≥Ω 曲线t＝0.5

[0094] Ω 1t＝1.0 ≥Ω 曲线t＝1.0

[0095] and so on

[0096] Ω 1t＝5.0 ≥Ω 曲线t＝5.0

[0097] where Ω 曲线t represents the speed ratio of the pump at time t in each loop; it is considered that the speed of the pump in a loop decreases to meet the curve. If a set of the above does not meet, it is considered that the speed of the pump decreases to not meet the curve. Similarly, the two-loop and three-loop are calculated and compared in the above manner.

[0098] Step eight: final determination of the test results: according to steps five to seven, the calculation and comparison are implemented, if all requirements are met, it is considered that the test is preliminarily qualified, and subsequent unit power increase and other operations can be carried out. When the unit reaches full power again, the reactor coolant flow test according to the heat balance calculation is re-executed, and the measured reactor coolant system three-loop flow rates Q 1n , Q 2n , Q 3n are respectively replaced by Q1, Q2, Q3 in steps five and six, if the comparison of steps five and six is still met, it is considered that the test meets the requirements, and the test is qualified. If any loop flow rate or total flow rate in steps five or six does not meet, it is considered that the test is unqualified. If the flow rates in steps five or six meet the requirements, but any one group of data or multiple data in step seven does not meet the curve requirements, it is preliminarily considered that the test is qualified, but has defects. When the unit reaches full power again, the reactor coolant flow test according to the heat balance calculation is re-executed, and the measured reactor coolant system three-loop flow rates Q 1n , Q 2n , Q 3n are respectively replaced by Q1, Q2, Q3 in steps five and six, if the comparison of steps five and six is still met, it is considered that the test flow rate meets the requirements, and the test is qualified, but has defects.

Claims

1. A method of determining a nuclear reactor coolant pump inertial flow test, characterized by: The one-loop reactor coolant system has three loops, comprising the following steps: Step 1: Collect the flow of three loops, the speed of three reactor coolant pumps; Step 2: Stop all reactor coolant pumps at the same time; Step 3: Take the three reactor coolant pumps as zero time, record the flow and pump speed of three loops at different times; Step 4: Calculate the reactor coolant flow test report according to the heat balance, and record the flow of three loops of the reactor coolant system during the stable operation of the last fuel cycle as Q1, Q2 and Q3; Step 5: Preliminary determine whether the flow of each loop meets the requirements; Step 6: Preliminary determine whether the total flow of the reactor core coolant meets the requirements; Step 7: Compare the speed of each loop pump with the design curve; Step 8: Finally determine the test results.

2. The method of claim 1, wherein: Step 3: Collect a group of data every 0.1s.

3. The method of claim 1, wherein: Step five: The preliminary judgment method is that the reactor coolant pump inertial flow test requires that the minimum flow cannot be lower than the flow Q 准则t = 4.0, and the uncertainty of the speed measuring instrument together with the instrument channel is η, then the corresponding speed Δn = η × n 额定 , n 额定 is the rated flow of the three-loop reactor coolant pump, then whether the flow of one loop meets the test criterion requirement is judged according to the following formula: Q 1t = 4.0 is the flow rate of the loop at the time of pump stop 4.0 s, n 1t＝4.0 = 4.0 is the pump speed of the loop after 4 s of pump stop, n 1t＝0.0 = 4.0 is the pump speed of the loop after 0 s of pump stop, and Q 1t = 4.0 > Q 准则t = 4.0, it is considered that the flow rate of the loop preliminarily meets the requirement, otherwise it does not meet the requirement; for the second loop: Q 2t = 4.0 is the flow rate of the double loop at the time of pump stop 4.0 s, n 2t＝4.0 = 4.0 is the pump speed 4 s after the double loop pump stops, n 2t＝0.0 = 4.0 is the pump speed 0 s after the double loop pump stops, and Q 2t = 4.0 > Q 准则t = 4.0, it is considered that the double loop flow rate preliminarily meets the requirements, otherwise it does not meet the requirements; for the triple loop: Q 3t = 4.0 is the flow rate of the three loops at the time of pump stop 4.0 s, n 3t＝4.0 = 4.0 is the pump speed after 4 s of pump stop of the three loops, n 3t＝0.0 = 4.0 is the pump speed after 0 s of pump stop of the three loops, as Q 3t = 4.0 > Q 准则t = 4.0, it is considered that the three loop flow rate preliminarily meets the requirements, otherwise it does not meet the requirements.

4. The method of claim 3, wherein: Step 6: Calculate the flow of each loop at 4.1s after the pump is stopped according to step 5, one loop is: Q 1t = 4.1 is the flow rate of the loop at pump stop 4.1 s, n 1t＝4.1 is the pump speed at 4.1 s after pump stop; Two loops are: Q 2t = 4.1 is the flow rate of the double loop at pump stop 4.1 s, n 2t＝4.1 is the pump speed at 4.1 s after pump stop of the double loop; Three loops are: Q 3t = 4.1 is the flow rate of the three loops at 4.1 s after pump trip, n 3t＝4.1 = 4.1 s after pump trip, the reactor coolant pump inertial flow test requires that the core flow rate cannot be lower than the flow rate Q 准则t = 4.1, then the following comparison is made: Q 1t = 4.1 + Q 2t = 4.1 + Q 3t = 4.1 > Q 准则t = 4.1 If the above formula is met, it is considered that the total flow of the reactor core preliminarily meets the requirements.

5. The method of claim 4, wherein: Step 7: According to the requirements of the upstream file, the evaluation requirements of the speed reduction curve in the reactor one-loop coolant pump inertial flow test are as follows: the speed ratio is: And so on: where Ω 1t n represents the speed ratio of the pump at time t in the loop; n 1t is the pump speed at time t after the pump is stopped in the loop; If so: Ω 1t＝0.0 ≥Ω 曲线t＝0.0 Ω 1t＝0.5 ≥Ω 曲线t＝0.5 Ω 1t＝1.0 ≥Ω 曲线t＝1.0 and so on 1t＝5.0 ≥Ω 曲线t＝5.0 where Ω 曲线t represents the speed ratio of the pump at time t for each loop; if a set of the above does not satisfy the curve, it is considered that the pump speed drop does not satisfy the curve.

6. The method of claim 5, wherein: The second loop and the third loop are calculated and compared according to the first loop.

7. The method of claim 5, wherein: Step eight: According to step five to step seven, if all requirements are met, the test is considered to be preliminarily qualified, and subsequent unit power increase operation is carried out. When the unit reaches full power again, the reactor coolant flow test is re-performed according to the heat balance calculation, and the measured reactor coolant system three loop flow rates Q 1n , Q 2n , Q 3n respectively replace Q1, Q2, Q3 in step five and step six, if the comparison still meets step five and step six, the test is considered to finally meet the requirements and the test is qualified.

8. The method of claim 7, wherein: Step 8: If the flow of any loop or the total flow does not meet the requirements in step 5 or step 6, the test is considered unqualified.

9. The method of claim 8, wherein: Step eight: If the flow rates of step five or step six all meet the requirements, but any one group of data or multiple data of step seven does not meet the requirements, then the test is preliminarily considered to be qualified but defective, and the unit is required to reach full power again, and the test of calculating the flow rate of the reactor coolant according to the heat balance is re-executed, and the flow rates Q 1n , Q 2n , Q 3n of the three loops of the reactor coolant system are respectively replaced by Q1, Q2, Q3 in step five and step six, and if the comparison still meets step five and step six, then the test flow rate is considered to meet the requirements, and the test is qualified but defective.

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