阅读说明：本技术 一种压水堆核电厂极小破口失水事故应对方法 (Method for coping with extremely-small-break water loss accident of pressurized water reactor nuclear power plant ) 是由 党高健 丁书华 冉旭 吴清 冷贵君 刘昌文 陈伟 吴丹 钱立波 申亚欧 李仲春 于 2020-05-15 设计创作，主要内容包括：本发明公开了一种压水堆核电厂极小破口失水事故应对方法,包括：检测压水堆核电厂的主系统过冷状态、二次侧热阱状态、主系统压力状态和稳压器水位状态；根据检测结果,判断是否满足终止安注准则,当满足终止安注准则时,则对安注泵依次执行停运操作；执行停运安注泵操作的过程中,实时监测主系统过冷状态和稳压器水位状态,若主系统过冷状态或稳压器水位状态不满足终止安注准则,则启动停运的安注泵；重复上述步骤,直至所有安注泵均停止运行。本发明通过设置有效的安注终止准则、制定合理的安注终止步骤等,实现了在发生一回路极小破口事故后,能够有效终止安注并维持核电厂处于安全稳定状态。(The invention discloses a method for coping with a minimal breach water loss accident of a pressurized water reactor nuclear power plant, which comprises the following steps: detecting a main system supercooling state, a secondary side heat trap state, a main system pressure state and a voltage stabilizer water level state of the pressurized water reactor nuclear power plant; judging whether the safety injection stopping criterion is met or not according to the detection result, and when the safety injection stopping criterion is met, sequentially stopping the operation of the safety injection pump; monitoring the supercooling state of a main system and the water level state of a voltage stabilizer in real time in the process of executing the operation of the shutdown safety injection pump, and starting the shutdown safety injection pump if the supercooling state of the main system or the water level state of the voltage stabilizer does not meet the safety injection stopping criterion; and repeating the steps until all the safety injection pumps stop running. According to the invention, by setting an effective safety injection termination criterion, formulating a reasonable safety injection termination step and the like, the safety injection can be effectively terminated and the nuclear power plant can be maintained in a safe and stable state after a primary circuit minimum breach accident occurs.)

1. A coping method for a minimal breach water loss accident of a pressurized water reactor nuclear power plant is characterized by comprising the following steps:

s1: detecting an operating condition of a pressurized water reactor nuclear power plant, the operating condition comprising: a main system supercooling state, a secondary side heat trap state, a main system pressure state and a voltage stabilizer water level state;

s2: judging whether the running states of the pressurized water reactor nuclear power plant meet safety injection stopping criteria or not according to the detection result of the step S1, and when the running states meet the safety injection stopping criteria, sequentially stopping the safety injection pumps;

s3: monitoring the main system supercooling state and the voltage stabilizer water level state in real time in the process of executing the operation of the shutdown safety injection pump, and starting the shutdown safety injection pump if the main system supercooling state or the voltage stabilizer water level state does not meet the safety injection stopping criterion;

s4: and repeating the steps S1-S4 until all the safety injection pumps stop running.

2. The method for coping with minimal break loss of coolant accident of pressurized water reactor nuclear power plant according to claim 1, further comprising the steps of:

s5: detecting the main system supercooling state and the voltage stabilizer water level state;

s6: if the main system supercooling state does not meet the safety injection stopping criterion, restarting the stopped safety injection pump; if the water level state of the voltage stabilizer does not meet the safety injection stopping criterion, the water level of the voltage stabilizer is maintained by controlling the upper charging flow, and if the water level of the voltage stabilizer cannot be maintained by adjusting the upper charging flow, the stopped safety injection pump is restarted.

3. The method for coping with minimal break loss of coolant accident of pressurized water reactor nuclear power plant according to claim 2, further comprising the steps of:

s7: and if the main system supercooling state and the water level state of the pressure stabilizer meet the safety injection stopping criterion, controlling the pressure, the temperature and the water level of a loop.

4. The method according to claim 3, wherein the pressure of the primary loop is a pressurizer pressure, the temperature of the primary loop is a primary system temperature, and the water level of the primary loop is a pressurizer water level and a steam generator water level.

5. The method for responding to the minimal breach loss of coolant accident of the pressurized water reactor nuclear power plant according to claim 4,

stabilizing the pressure of the voltage stabilizer by controlling an electric heater of the voltage stabilizer and normally spraying;

stabilizing the water level of the voltage stabilizer by controlling the upper charging and lower discharging flow;

stabilizing the temperature of the main system by controlling the steam discharge;

the steam generator level is stabilized by the auxiliary feedwater flow.

6. The method for handling the minimal breach loss of coolant accident of the pressurized water reactor nuclear power plant according to claim 1, wherein the safety injection stopping criterion comprises:

main system supercooled state: the supercooling degree of the reactor core outlet is greater than the temperature threshold value;

secondary side hot trap state: the total flow of the steam generator is greater than a flow threshold or the narrow-range water level of the steam generator is greater than a first water level threshold;

primary system pressure state: the main system pressure is at steady or rising;

the water level state of the voltage stabilizer: the water level of the voltage stabilizer is greater than the second water level threshold value.

7. The method for coping with the loss of coolant accident of the pressurized water reactor nuclear power plant with the minimum breach as set forth in claim 6, wherein the degree of supercooling at the core outlet is greater than a temperature threshold value, and the temperature threshold value ranges from 15 ℃ to 25 ℃;

the total flow of the steam generator is larger than a flow threshold value, and the range of the flow threshold value is 80m³/h-100m³/h；

The water level of the steam generator in the narrow range is greater than a first water level threshold, and the first water level threshold is 5% -20%;

the water level of the voltage stabilizer is greater than a second water level threshold value, and the second water level threshold value is 20% -40%.

8. The method for handling the minimal breach loss of coolant accident of the pressurized water reactor nuclear power plant as recited in claim 1, wherein the safety injection pump comprises a plurality of high pressure safety injection pumps and a plurality of low pressure safety injection pumps.

9. The method for handling the minimal breach loss of coolant accident of the pressurized water reactor nuclear power plant as recited in claim 1, wherein the operation of the low-pressure safety injection pumps is stopped after the operation of the high-pressure safety injection pumps is stopped in sequence.

10. The method for handling the minimal breach loss of coolant accident of the pressurized water reactor nuclear power plant as recited in claim 8, wherein the plurality of high-pressure safety injection pumps are two high-pressure safety injection pumps, and the plurality of low-pressure safety injection pumps are two low-pressure safety injection pumps.

Technical Field

The invention relates to an accident handling scheme of a pressurized water reactor nuclear power plant (pressurized water reactor nuclear power plant), in particular to a handling method of a minimum break loss accident of the pressurized water reactor nuclear power plant.

Background

The pressurized water reactor nuclear power plant has a tiny breach water loss accident which causes reactor shutdown and enables the upper charge flow to compensate the breach flow after the reactor shutdown. For the accident, after the break occurs, the pressure of the main system is very high, and the flow of the break is larger than the upper charging flow, so that the pressure of the main system and the water level of the pressure stabilizer are continuously reduced, and the reactor shutdown and the safety injection pump are triggered to be put into operation. After the shutdown, along with the reduction of the pressure of the main system, when the crevasse flow is lower than the upper charging flow, the safety injection pump does not need to continue to operate, and the crevasse flow can be compensated only by the upper charging flow. In this case, if the safety injection pump continues to operate, the pressure of the main system may continuously rise, and the overpressure protection valve of the pressure stabilizer is triggered to open, so that the loss of coolant accident with more serious consequences is caused. Therefore, it is necessary to select the right time and take reasonable measures to stop the operation of the safety injection pump and maintain the nuclear power plant in a stable state so as to ensure the safety of the reactor.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the safety injection pump continues to operate to cause more serious loss of coolant accidents when minimum break loss of coolant accidents occur, and the aim is to provide a method for coping the minimum break loss of coolant accidents of a pressurized water reactor nuclear power plant.

The invention is realized by the following technical scheme:

a coping method for a minimal breach water loss accident of a pressurized water reactor nuclear power plant comprises the following steps: s1: detecting an operating condition of a pressurized water reactor nuclear power plant, the operating condition comprising: a main system supercooling state, a secondary side heat trap state, a main system pressure state and a voltage stabilizer water level state; s2: judging whether the running states of the pressurized water reactor nuclear power plant meet safety injection stopping criteria or not according to the detection result of the step S1, and when the running states meet the safety injection stopping criteria, sequentially stopping the safety injection pumps; s3: monitoring the main system supercooling state and the voltage stabilizer water level state in real time in the process of executing the operation of the shutdown safety injection pump, and starting the shutdown safety injection pump if the main system supercooling state or the voltage stabilizer water level state does not meet the safety injection stopping criterion; s4: and repeating the steps S1-S4 until all the safety injection pumps stop running.

The invention monitors the main system supercooling state, the secondary side heat trap state, the main system pressure state and the water level state of the pressure stabilizer in real time, judges whether the four states all meet the safety injection stopping criterion, and when all the states meet the safety injection stopping criterion, only an upper charge pump compensates the loss of the coolant at the breach, and stops operating the safety injection pump in sequence. And in the process of stopping the operation of the safety injection pump, after one safety injection pump is stopped, the supercooled state of the main system and the water level state of the pressure stabilizer are detected again. And when the main system is in the supercooled state or the water level state of the pressure stabilizer does not meet the safety injection stopping criterion, restarting the safety injection pump which stops running in the last step. And repeating the steps until all the safety injection pumps stop running. The method monitors the main system supercooling state, the secondary side heat trap state, the main system pressure state and the water level state of the pressure stabilizer of the pressurized water reactor nuclear power plant in the whole process, and adopts corresponding different corresponding measures (stopping the safety injection pump or restarting the safety injection pump) through judging the four states in different periods, so that the safe and stable operation of the pressurized water reactor nuclear power plant is guaranteed.

Further, the method also comprises the following steps: s5: detecting the main system supercooling state and the voltage stabilizer water level state; s6: if the main system supercooling state does not meet the safety injection stopping criterion, restarting the stopped safety injection pump; if the water level state of the voltage stabilizer does not meet the safety injection stopping criterion, the water level of the voltage stabilizer is maintained by controlling the upper charging flow, and if the water level of the voltage stabilizer cannot be maintained by adjusting the upper charging flow, the stopped safety injection pump is restarted.

When all safety injection pumps stop operating, the main system supercooling state and the water level state of the pressure stabilizer are detected again, any one state does not meet the safety injection stopping criterion, corresponding different measures are taken, and the safe and stable operation of the pressurized water reactor nuclear power plant is further guaranteed.

Further, the method also comprises the following steps: s7: and if the main system supercooling state and the water level state of the pressure stabilizer meet the safety injection stopping criterion, controlling the pressure, the temperature and the water level of a loop.

When all safety injection pumps stop operating, the main system supercooling state and the pressure stabilizer water level state are detected again, and when the two states meet the safety injection stopping criterion, the safe and stable operation of the pressurized water reactor nuclear power plant is guaranteed by controlling the pressure, the temperature and the water level of a loop.

Further, the pressure of the primary loop is the pressure of the pressure stabilizer, the temperature of the primary loop is the temperature of the main system, and the water level of the primary loop is the water level of the pressure stabilizer and the water level of the steam generator.

Further, the pressure of the voltage stabilizer is stabilized by controlling the electric heater of the voltage stabilizer and normal spraying; stabilizing the water level of the voltage stabilizer by controlling the upper charging and lower discharging flow; stabilizing the temperature of the main system by controlling the steam discharge; the steam generator level is stabilized by the auxiliary feedwater flow.

Further, the stopping safety injection criterion comprises: main system supercooled state: the supercooling degree of the reactor core outlet is greater than the temperature threshold value; secondary side hot trap state: the total flow of the steam generator is greater than a flow threshold or the narrow-range water level of the steam generator is greater than a first water level threshold; primary system pressure state: the main system pressure is at steady or rising; the water level state of the voltage stabilizer: the water level of the voltage stabilizer is greater than the second water level threshold value.

The most appropriate time for stopping the safety injection pump is judged by setting a specific safety injection stopping criterion, namely setting a precondition for stopping the safety injection pump.

Further, the supercooling degree of the reactor core outlet is greater than a temperature threshold value, and the temperature threshold value range is 15-25 ℃; the total flow of the steam generator is larger than a flow threshold value, and the range of the flow threshold value is 80m³/h-100m³H; the water level of the steam generator in the narrow range is greater than a first water level threshold, and the first water level threshold is 10% -20%; the water level of the voltage stabilizer is greater than a second water level threshold value, and the second water level threshold value is 20% -40%.

Further, the safety injection pump comprises a plurality of high-pressure safety injection pumps and a plurality of low-pressure safety injection pumps. And after the plurality of high-pressure safety injection pumps are stopped to operate in sequence, the plurality of low-pressure safety injection pumps are stopped to operate in sequence. The plurality of high-pressure safety injection pumps are two high-pressure safety injection pumps, and the plurality of low-pressure safety injection pumps are two low-pressure safety injection pumps.

Compared with the prior art, the invention has the following advantages and beneficial effects:

1. the invention can determine the accurate safety injection termination time, namely the accurate time for stopping the safety injection pump through the safety injection termination criterion;

2. the operation steps set by the invention can safely and effectively stop the safety injection pump;

3. the heat removal means adopted by the invention can smoothly lead out the waste heat of the reactor core, and ensure that the nuclear power plant is controlled in a stable state when a primary circuit minimum break accident occurs.

Drawings

The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:

FIG. 1 is a schematic flow chart of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.