CN-115862906-B - Method for exiting major repair critical path of voltage stabilizer of nuclear power unit

CN115862906BCN 115862906 BCN115862906 BCN 115862906BCN-115862906-B

Abstract

The application relates to a method for exiting a major repair critical path of a nuclear power unit voltage stabilizer, which comprises the following steps of putting all heaters in the voltage stabilizer into operation to ensure that the saturated state in the voltage stabilizer is maintained, putting an RRA system into operation to enable a loop to be cooled at a preset cooling rate, maintaining the main pump shaft seal injection amount, adjusting the upper charging flow of the loop to be within a first preset flow range and the lower discharging flow to be within a second preset flow range so as to enable the water level in the voltage stabilizer to rise, adjusting a spray valve in the voltage stabilizer to enable the pressure of the loop to be maintained at the preset pressure, switching a discharging control valve to control the pressure of the loop when the water level of the voltage stabilizer reaches the first preset water level, and adjusting the opening of the spray valve in the voltage stabilizer according to the change of the lower discharging flow until the opening of the discharging control valve is unchanged before the water level of the voltage stabilizer reaches the second preset water level, and completely annihilating a steam cavity. The process of the voltage stabilizer steam-out cavity does not occupy the time of major repair critical path, thereby shortening the time of major repair critical path and ensuring the period of major repair.

Inventors

WANG SHUQIANG
LI JUN

Assignees

岭澳核电有限公司
岭东核电有限公司
广东核电合营有限公司
大亚湾核电运营管理有限责任公司
中国广核集团有限公司

Dates

Publication Date: 20260508
Application Date: 20221216

Claims (10)

1. The method for exiting the major repair critical path of the voltage stabilizer of the nuclear power unit is characterized by comprising the following steps of: s10, all heaters in the voltage stabilizer are put into operation so as to ensure that the saturated state in the voltage stabilizer is maintained; s20, putting the waste heat discharging system into operation, so that the temperature of the loop is reduced at a preset temperature reduction rate; s40, maintaining the main pump shaft seal injection amount, adjusting the upper charging flow of a loop to be within a first preset flow range, and adjusting the lower discharging flow to be within a second preset flow range so as to enable the water level in the pressure stabilizer to rise; S60, adjusting a spray valve in the pressure stabilizer to maintain the pressure of the first loop at a preset pressure; S70, when the water level of the pressure stabilizer reaches a first preset water level, switching the down-leakage control valve to control the pressure of a loop; And S90, before the water level of the pressure stabilizer reaches a second preset water level, the second preset water level is larger than the first preset water level, and the opening of a spray valve in the pressure stabilizer is adjusted according to the change of the downward leakage flow until the opening of the downward leakage control valve is unchanged, so that the steam cavity is completely annihilated.
2. The method of exiting a major repair critical path for a nuclear power unit voltage regulator of claim 1, further comprising, after step S90, the steps of: S100, the heaters are withdrawn from the voltage stabilizer one by one, and meanwhile, the spray valve in the voltage stabilizer is adjusted to be fully opened.
3. The method for exiting a major repair critical path of a voltage regulator of a nuclear power unit according to claim 2, wherein in said step S100, adjusting a spray valve in the voltage regulator to a full open state, specifically comprises: and adjusting the spray valve in the voltage stabilizer to a first preset opening degree for a first preset time, and adjusting the spray valve in the voltage stabilizer to be fully opened.
4. The method for exiting a major repair critical path of a voltage regulator of a nuclear power unit according to claim 1, wherein said step S20 specifically comprises the steps of: s21, opening an inlet valve of the waste heat discharging system, and preheating and heating the waste heat discharging system; S22, adjusting the upper charging flow and the lower discharging flow of the first loop to enable the water level of the voltage stabilizer to reach a third preset water level, wherein the third preset water level is lower than the first preset water level; s23, opening an outlet valve of the waste heat discharging system, and adjusting an adjusting valve of the waste heat discharging system to enable the primary circuit to be cooled at a preset cooling speed.
5. The method for exiting a major repair critical path of a nuclear power unit voltage regulator according to claim 1, wherein in said step S90, the opening degree of a spray valve in the voltage regulator is adjusted according to the change of the down-leak flow, specifically comprising: when the increase of the discharging flow exceeds the upper limit margin, the opening degree of a spray valve in the voltage stabilizer is regulated; when the reduction of the discharging flow exceeds the lower limit margin, the opening degree of the spray valve in the pressure stabilizer is reduced.
6. The method of exiting a major repair critical path for a nuclear power unit voltage regulator of claim 1, further comprising, after said step S70, the steps of: and S80, maintaining the charging flow unchanged, and opening the low-pressure relief loop regulating valve to be fully opened.
7. The method of exiting a major repair critical path for a nuclear power unit voltage regulator of claim 1, further comprising, prior to said step S40, the steps of: s30, blowing the gas cavity of the voltage stabilizer.
8. The method of exiting a major repair critical path for a nuclear power unit voltage regulator according to claim 1, further comprising, after said step S40, the steps of: s50, controlling the REA system to supplement water to the volume control box, and simultaneously blowing air to the volume control box.
9. The method for exiting a major repair critical path as claimed in claim 3, wherein, The first preset opening is 50% -60%, and the first preset time is more than 1 h.
10. The method for exiting a major repair critical path as claimed in claim 4, wherein, The first preset flow range is 20 t/h-25 t/h, the second preset flow range is 10 t/h-15 t/h, the preset pressure is 25bar, the preset cooling rate is 28 ℃, the first preset water level is 1.8m, the second preset water level is 2.2m, and the third preset water level is-1 m.

Description

Method for exiting major repair critical path of voltage stabilizer of nuclear power unit Technical Field The application relates to the technical field of nuclear power station voltage regulators, in particular to a method for exiting a major repair critical path of a nuclear power unit voltage regulator. Background The nuclear power reactor is characterized in that a loop shares a voltage stabilizer and a pressure relief box corresponding to the voltage stabilizer. The pressure of the reactor coolant system is maintained stable by means of the electric heating element of the pressurizer and the automatic regulation of the atomizer. At present, in the nuclear power overhaul process, the operation of a steam-extinguishing cavity is required to be executed before the temperature of a first loop of the nuclear power reactor is reduced to 130 ℃, the operation of the steam-extinguishing cavity is executed first, and the operation of quick cooling of the first loop is executed after the steam cavity is annihilated. Therefore, the steam-out cavity of the voltage stabilizer occupies a major repair critical path, and meanwhile, the pressure and the temperature of a reactor coolant system (RCP system) generate severe transient changes in the steam-out cavity process, and the transient changes can cause the unit to generate operation events exceeding the operation limit, generate hydrogen rebound and finally cause the delay of the major repair period. Disclosure of Invention Based on the method, the application provides a method for exiting the major repair critical path of the voltage stabilizer of the nuclear power unit, and the voltage stabilizer steam-out cavity is carried out in the process of cooling a loop, so that the time of the major repair critical path is not occupied in the process of the voltage stabilizer steam-out cavity, thereby shortening the time of the major repair critical path and ensuring the major repair period. The embodiment of the application provides a method for exiting a major repair critical path of a voltage stabilizer of a nuclear power unit, which comprises the following steps: s10, all heaters in the voltage stabilizer are put into operation so as to ensure that the saturated state in the voltage stabilizer is maintained; s20, putting the waste heat discharging system into operation, so that the temperature of the loop is reduced at a preset temperature reduction rate; S40, maintaining the injection quantity of the main pump shaft seal, adjusting the upper charging flow of a loop to be within a first preset flow range, and adjusting the lower discharging flow to be within a second preset flow range so as to enable the water level in the pressure stabilizer to rise; S60, adjusting a spray valve in the pressure stabilizer to maintain the pressure of the first loop at a preset pressure; S70, when the water level of the pressure stabilizer reaches a first preset water level, switching the down-leakage control valve to control the pressure of a loop; And S90, before the water level of the pressure stabilizer reaches a second preset water level, the second preset water level is larger than the first preset water level, and the opening of a spray valve in the pressure stabilizer is adjusted according to the change of the downward leakage flow until the opening of the downward leakage control valve is unchanged, so that the steam cavity is completely annihilated. In some embodiments, after the step S90, the method further comprises the steps of: S100, the heaters are withdrawn from the voltage stabilizer one by one, and meanwhile, the spray valve in the voltage stabilizer is adjusted to be fully opened. In some embodiments, in the step S100, adjusting the spray valve in the regulator to be fully opened specifically includes: and adjusting the spray valve in the voltage stabilizer to a first preset opening degree for a first preset time, and adjusting the spray valve in the voltage stabilizer to be fully opened. In some embodiments, the step S20 specifically includes the following steps: s21, opening an inlet valve of the waste heat discharging system, and preheating and heating the waste heat discharging system; S22, adjusting the up-charging flow and the down-discharging flow of a loop to enable the water level of the voltage stabilizer to reach a third preset water level, wherein the third preset water level is lower than the first preset water level; s23, opening an outlet valve of the waste heat discharging system, and adjusting an adjusting valve of the waste heat discharging system to enable the primary circuit to be cooled at a preset cooling speed. In some embodiments, in the step S90, adjusting the opening of the spray valve in the pressure regulator according to the change of the drain flow specifically includes: when the increase of the discharging flow exceeds the upper limit margin, the opening degree of a spray valve in the voltage stabilizer is regulated; when the reduction o