A boron flushing water discharge method and system applied to an emergency boron injection pump of a VVER unit

Abstract

The present application relates to the field of nuclear power, in particular to a boron flushing water discharge method and system of an emergency boron injection pump applied to a VVER unit. The method is as follows: the boron flushing water discharge system is set to an initial state; during normal unit power operation, when boron flushing of the emergency boron injection pump is performed, the boron flushing water electric valve is opened, the three-way valve is operated, and the discharge direction is changed from the initial state to the boron-containing wastewater pit, while the flushing water amount is observed to see whether it meets the requirements; if the flushing water amount meets the requirements, the flushing water is adjusted to discharge to the non-boron-containing wastewater pit; if the flushing water amount does not meet the requirements, the water supply flow is adjusted according to the instructions, and after the flushing water amount meets the requirements, the flushing water is adjusted to discharge to the non-boron-containing wastewater pit. The system is connected to the boron flushing water discharge pipeline after the three-way valve, and the boron flushing discharge pipeline is connected to the non-boron-containing wastewater pit. The present application reduces wastewater discharge, increases boron recovery, prevents primary loop water pollution, can also assist in judging valve leakage, and reduces personnel workload.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nuclear power, in particular to a boron flushing water discharge method and system for an emergency boron injection pump applied to a VVER unit. BACKGROUND

[0002] In order to reduce the damage of boron crystallization to the shaft seal surface of the pump body, the emergency boron injection pump needs to be subjected to boron flushing operation. The boron flushing water source of the emergency boron injection pump comes from the primary loop important user cooling water system. Since the long-term operation of the 3 / 4 unit of Tianwan Nuclear Power Plant, the water quality of the primary loop important user cooling water system has two main characteristics:

[0003] 1) The slow-release agent needs to be added to the primary loop important user cooling water system to inhibit copper ions and ensure water quality. The primary loop important user cooling water system contains corrosion inhibitor.

[0004] 2) The primary loop important user cooling water system may exceed the standard due to user leakage. Under the operating condition of the unit, when the primary loop important user cooling water exceeds the standard, dynamic water replacement is adopted to reduce the radioactivity. Dynamic water replacement refers to starting the pump of the primary loop important user cooling water system, opening the drain valve and the water supply valve, and replacing water by draining and supplying water at the same time. In this way, the radioactivity is reduced, and the content of chemical reagent is also reduced. That is, after the primary loop important user cooling water system is subjected to dynamic water replacement, the boron flushing water at this time can be completely recycled, that is, it can be discharged to the boron-containing waste water pit. The above two characteristics will affect the discharge of boron flushing water. At the same time, the boron flushing water contains boric acid, and this part of boric acid can be recycled.

[0005] The current pipeline design is shown in Figure 1 The boron flushing water first passes through the eight-meter pump house internal boron flushing water total supply pipeline 7, passes through a supply pipeline electric valve 1 and a supply pipeline regulating valve 2, and then the supply pipeline is divided into three paths to enter the internal chamber 3 of the emergency boron injection pump, flows out from the pump chamber through three branch pipes, enters the flushing water discharge pipeline, and flows through the three-way valve 5 and the peep water pan 6 to the 4m neutron source room, and is finally connected to the boron-containing waste water pit.

[0006] The pipeline design cannot distinguish between boron-containing waste water and non-boron-containing waste water, and also cannot distinguish whether the washing water can be recycled due to exceeding the standard of radioactivity and corrosion inhibitor, resulting in excessive waste water discharge and difficulty in recycling boric acid. SUMMARY

[0007] The technical problem to be solved by the present application is to provide a boron flushing water discharge method and system for an emergency boron injection pump applied to a VVER unit, which reduces waste water discharge, increases boron recovery, prevents primary loop water pollution, and can also assist in judging valve leakage and reduce personnel workload.

[0008] The application provides a boron flushing water discharging method for an emergency boron injection pump applied to a VVER unit.

[0009] Step one: set the boron flushing water discharging system to an initial state;

[0010] Step two: during normal unit power operation, open the boron flushing water electric valve and operate the three-way valve to change the direction of the boron flushing water from the initial direction to the boron-free waste water pit to the boron-containing waste water pit, and observe whether the flushing water amount meets the requirements;

[0011] If the flushing water amount meets the requirements, adjust the flushing water to the boron-free waste water pit;

[0012] If the flushing water amount does not meet the requirements, adjust the water supply flow according to the instruction, and after the flushing water amount meets the requirements, adjust the flushing water to the boron-free waste water pit;

[0013] After the dynamic water exchange of the primary loop important user cooling water is performed, when the boron flushing of the emergency boron injection pump is performed,

[0014] According to the content of the waste water corrosion inhibitor and boric acid, the waste water is discharged to the boron-containing or boron-free pit; as long as the content of the waste water corrosion inhibitor exceeds the standard, the waste water is discharged to the boron-free waste water pit; when the content of the waste water corrosion inhibitor is lower than the standard and the content of the boric acid is higher than the standard, the waste water is discharged to the boron-containing waste water pit.

[0015] Further, the initial state is that the boron flushing water electric valve is closed, the boron flushing water manual valve is kept at a fixed opening to maintain the boron flushing water amount requirement, and the three-way valve is switched to the boron-free waste water pit.

[0016] Further, before the boron flushing of the emergency boron injection pump is performed, the flushing water amount is kept between 240 and 300 L / h.

[0017] Further, the judgment standard that the flushing water amount meets the requirements is that the flushing water flows out of the water receiving disc and the flushing is normal.

[0018] Further, when the content of the waste water corrosion inhibitor and the boric acid is lower than the standard, the waste water is discharged to the boron-containing waste water pit, and the desalted water is recovered after treatment;

[0019] When the content of the waste water corrosion inhibitor is lower than the standard and the content of the boric acid is higher than the standard, the waste water is discharged to the boron-containing waste water pit, and the boric acid is recovered after treatment.

[0020] The application further provides a boron flushing water discharging system for an emergency boron injection pump applied to a VVER unit, a boron flushing water discharging pipeline is connected to the three-way valve, and the boron flushing water discharging pipeline is connected to the boron-free waste water pit.

[0021] Further, an air venting pipeline is installed at the outlet of the boron flushing water discharge pipeline.

[0022] Further, an emergency boron injection pump is arranged in the pump house, and the boron flushing water discharge pipeline passes through the pump house and the neutron source and is finally connected to the boron-free wastewater pit.

[0023] Compared with the prior art, the boron flushing water discharge method and system of the emergency boron injection pump applied to the VVER unit of the application solves the problem of boron flushing water discharge of the emergency boron injection pump of the unit, and has the following advantages

[0024] Beneficial effects:

[0025] 1) The discharge direction of the boron flushing water of the emergency boron injection pump is selectively realized, a wastewater discharge mode is added, and the pollution of the primary loop water caused by the excessive ion and reagent concentration in the wastewater is avoided.

[0026] 2) The problem of rapid failure of the resin bed caused by the misentry of high-concentration corrosion inhibitor into the primary loop wastewater treatment system is prevented.

[0027] 3) The problem of wastewater recovery after dynamic water exchange is solved, and the recovery and utilization rate of boron in the wastewater is improved.

[0028] 4) A troubleshooting mode for the unexplained rise of the liquid level in the pit in the pump house of the emergency boron injection pump is added. If the liquid level in the boron-containing wastewater pit is rising, the three-way valve can be opened on site after the boron flushing water supply electric valve is not opened by the main control to determine whether the electric valve is leaking.

[0029] 5) The water flow can be measured more conveniently in the open funnel.

[0030] The boron flushing requirement of the emergency boron injection pump and the existing difficulties of the system are comprehensively considered in the application, and the purposes of energy saving, emission reduction and resource waste reduction are achieved. At the same time, the actual implementation of this scheme is also relatively easy, and the existing pipelines and spare parts of the unit are used without the need to add complex equipment or purchase new devices. The wastewater discharge problem solved by using this scheme is simple and efficient, reliable and economical. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 a structure diagram of the boron flushing water discharge system of the prior art emergency boron injection pump is shown;

[0032] Figure 2 a structure diagram of the boron flushing water discharge system of the emergency boron injection pump of the application is shown;

[0033] In the drawings,

[0034] 1 - borated water flush electric valve; 2 - borated water flush manual valve; 3 - plunger chamber of emergency borated pump; 4 - vent pipe; 5 - three-way valve; 6 - sight water receiving tray; 7 - borated water flush total supply pipeline; 8 - borated water flush discharge pipeline. DETAILED DESCRIPTION

[0035] In order to further understand the present application, the embodiments of the present application are described below in conjunction with the examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present application, but not for limiting the present application.

[0036] The embodiment of the present application discloses a borated water flush discharge method for an emergency borated pump applied to a VVER unit, comprising the following steps:

[0037] Step one: set the borated water flush discharge system to an initial state;

[0038] The initial state is that the borated water flush electric valve is closed, the borated water flush manual valve is kept at a fixed opening to maintain the borated water flush amount requirement, and the three-way valve is switched to discharge to a boron-free wastewater pit.

[0039] Step two: during normal unit power operation, when borated flushing of the emergency borated pump is performed, open the borated water flush electric valve, operate the three-way valve, and change from initial discharge to the boron-free wastewater pit to discharge to the boron-containing wastewater pit, and at the same time, observe whether the flush water amount meets the requirement;

[0040] The judgment standard for the flush water amount meeting the requirement is that there is flush water flowing out of the sight water receiving tray, and the flushing is normal;

[0041] If the flush water amount meets the requirement, adjust the flush water to discharge to the boron-free wastewater pit;

[0042] If the flush water amount does not meet the requirement, adjust the water supply flow according to the instruction, and after the flush water amount meets the requirement, adjust the flush water to discharge to the boron-free wastewater pit;

[0043] After dynamic water replacement of the primary circuit important user cooling water is performed, when borated flushing of the emergency borated pump is performed,

[0044] According to the content of the wastewater corrosion inhibitor and boric acid, discharge to the boron-containing or boron-free pit is selected; as long as the content of the wastewater corrosion inhibitor exceeds the standard, discharge to the boron-free wastewater pit is selected; when the content of the wastewater corrosion inhibitor is lower than the standard value and the content of boric acid is higher than the standard value, discharge to the boron-containing wastewater pit is selected;

[0045] Specifically:

[0046] When the content of the wastewater corrosion inhibitor and boric acid is lower than the standard value, discharge to the boron-containing wastewater pit is selected, and after treatment, desalted water is recovered;

[0047] When the content of the wastewater corrosion inhibitor is lower than the outline value, and the content of boric acid is higher than the outline value, then the wastewater containing boric acid is selected to be discharged to a pit, and the boric acid is recovered after treatment.

[0048] Before the boron flushing of the emergency boron injection pump is performed, the flushing water volume is kept between 240 and 300 L / h.

[0049] The boron flushing of the emergency boron injection pump is performed during power operation, and the on-site operator should quickly reduce the observation time when the three-way valve is switched to discharge to the pit containing boric acid wastewater, and immediately switch back to discharge to the pit not containing boric acid wastewater after observation, so as to prevent water pollution caused by unqualified wastewater quality.

[0050] The embodiment of the application also discloses a boron flushing water discharge system of an emergency boron injection pump applied to a VVER unit.

[0051] Specifically, the boron flushing water discharge system of the emergency boron injection pump applied to the VVER unit comprises:

[0052] The boron flushing water total supply pipeline 7 is connected to the plunger chamber 3 of the emergency boron injection pump, and the boron flushing water total supply pipeline 7 is divided into three branches to enter the internal chamber 3 of the emergency boron injection pump, flows out from the pump chamber through the three branches, enters the flushing water discharge pipeline, and is discharged through the three-way valve 5, the peep water tray 6, reaches the 4m neutron source room, and is finally connected to the pit containing boric acid wastewater.

[0053] The boron flushing water total supply pipeline 7 is connected to the plunger chamber 3 of the emergency boron injection pump, and the boron flushing water total supply pipeline 7 is divided into three branches to enter the internal chamber 3 of the emergency boron injection pump, flows out from the pump chamber through the three branches, enters the flushing water discharge pipeline, and is discharged through the three-way valve 5, the peep water tray 6, reaches the 4m neutron source room, and is finally connected to the pit containing boric acid wastewater.

[0054] The three-way valve 5 is also connected to the boron flushing discharge pipeline 8, and the boron flushing discharge pipeline 8 is connected to the pit not containing boric acid wastewater.

[0055] In order to prevent the pit water from being siphoned, the boron flushing discharge pipeline 8 is provided with a vent pipeline 4 at the outlet.

[0056] The actual pipeline design is as follows: after the original three-way valve, the pipeline passes through the 8m emergency boron injection pump pump room, the emergency boron injection pump is arranged in the pump room, passes through the 8m floor of the 4m neutron source room, and then passes through the northeast corner of the 4m neutron source room floor to reach the ceiling of the 0m safety pump room, the pit containing boric acid wastewater is arranged in the safety pump room, the ceiling is a steel grid structure, the distance between the ceiling and the ground is about 4m, and then the pipeline passes through the boundary cement wall of the same floor through the ceiling to reach the adjacent 0m important user cooling water pump room, and is finally discharged to the pit not containing boric acid wastewater.

[0057] The boron flushing water discharge system of the emergency boron injection pump applied to the VVER unit in the application improves the line in the technology without changing the original design pipeline, is convenient and safe, and reduces the cost.

[0058] The boron flushing water discharge system can recycle the boron in the waste water, reduce the waste water discharge, and prevent the one-loop water pollution.

[0059] Moreover, when the liquid level of the boron-containing waste water pit in which the emergency boron injection pump house is located rises for unknown reasons, the peep water saving disc can be used to assist in judging whether the liquid level rise is caused by the internal leakage of the boron flushing water supply valve. At this time, the flushing water electric valve is kept closed, the manual valve is placed according to the actual judgment, the three-way valve is switched to the boron-containing waste water pit by the on-site operator, and the peep window is observed. If there is continuous water flow from the peep disc, the upstream valve has internal leakage.

[0060] The on-site personnel determine that the method and system are reliable and feasible after a period of field operation, the method has been well verified in the No. 3 and No. 4 units of Jiangsu Nuclear Power, and the expected design purpose and effect are achieved.

[0061] The above description of the embodiments is only used to help understand the method of the application and its core idea. It should be pointed out that for ordinary skilled persons in the art, some improvements and modifications can be made to the application without departing from the principles of the application, and these improvements and modifications also fall within the protection scope of the claims of the application.

[0062] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the application. Various modifications to the embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the application. Therefore, the application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for discharging boron flushing water from an emergency boron injection pump of a VVER unit, characterized in that: The following steps are involved: Step 1: Set the boron flushing water discharge system to the initial state; Step 2: During normal unit power operation, when performing boron flushing of the emergency boron injection pump, open the boron flushing water electric valve and operate the three-way valve to switch from initially discharging to the boron-free wastewater pit to discharging to the boron-containing wastewater pit, while observing whether the flushing water volume meets the requirements; If the flushing water volume meets the requirements, adjust the flushing water to discharge into the boron-free wastewater pit; If the flushing water volume does not meet the requirements, adjust the water supply flow according to the instructions. After the flushing water volume meets the requirements, adjust the flushing water to discharge into the boron-free wastewater pit; After the dynamic water replacement of the cooling water of the important users in the primary circuit, when the emergency boron injection pump is flushed with boron, Based on the content of corrosion inhibitor and boric acid in the wastewater, choose to discharge it to a boron-containing or non-boron-containing pit; as long as the content of corrosion inhibitor in the wastewater exceeds the standard, choose to discharge it to a non-boron-containing wastewater pit; when the content of corrosion inhibitor and boric acid in the wastewater are both lower than the outline value, or when the content of corrosion inhibitor in the wastewater is lower than the outline value and the content of boric acid is higher than the outline value, choose to discharge it to a boron-containing wastewater pit; The initial state is that the boron flushing water electric valve is closed, the boron flushing water manual regulating valve maintains a fixed opening to maintain the boron flushing water volume requirement, and the three-way valve is switched to discharge to a boron-free wastewater pit.

2. The boron flushing water discharge method for an emergency boron injection pump of a VVER unit according to claim 1, characterized in that: Before performing boron flushing of the emergency boron injection pump, the flushing water volume should be maintained between 240 and 300 L / h.

3. The boron flushing water discharge method for an emergency boron injection pump applied to a VVER unit according to claim 1, characterized in that: The judgment standard that the flushing water volume meets the requirement is: flushing water flows out of the water receiving tray and the flushing is normal.

4. The boron flushing water discharge method for an emergency boron injection pump applied to a VVER unit according to claim 1, characterized in that: When the contents of corrosion inhibitor and boric acid in wastewater are lower than the outline values, the wastewater is discharged to the boron-containing wastewater pit, and then treated and desalted water is recovered; When the corrosion inhibitor content in the wastewater is lower than the outline value and the boric acid content is higher than the outline value, it will be discharged into a boron-containing wastewater pit for treatment and recovery of boric acid.

5. A boron flushing water discharge system using the boron flushing water discharge method according to any one of claims 1 to 4, characterized in that: A boron flushing water discharge pipeline is connected after the three-way valve, and the boron flushing discharge pipeline is connected to a boron-free wastewater pit.

6. The boron flushing water discharge system according to claim 5, characterized in that: An air pipeline is installed at the outlet of the boron flushing discharge pipeline.

7. The boron flushing water discharge system according to claim 5, characterized in that: The emergency boron injection pump is installed in the pump room, and the boron flushing water discharge pipeline passes through the pump room, the neutron source room, and is finally connected to the boron-free wastewater pit.

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