CN112289472A

CN112289472A - Passive water replenishing system of steam generator for passive nuclear power plant

Info

Publication number: CN112289472A
Application number: CN202011299269.6A
Authority: CN
Inventors: 缪正强; 马柏松; 程昭
Original assignee: Shandong Nuclear Power Co Ltd
Current assignee: Shandong Nuclear Power Co Ltd
Priority date: 2020-11-19
Filing date: 2020-11-19
Publication date: 2021-01-29

Abstract

The invention discloses a passive water replenishing system of a steam generator for a passive nuclear power plant, which further comprises the passive water replenishing system of the steam generator on the basis of a starting water supply system, wherein the passive water replenishing system of the steam generator comprises a heat exchanger and a pressure accumulation box, the heat exchanger is arranged in a condensation water tank, the bottom elevation of the condensation water tank is higher than the top elevation of the steam generator, a steam pipeline at the inlet of the heat exchanger is connected with the steam generator and a main steam pipeline, and an outlet pipeline of the heat exchanger is connected with a starting water supply main pipe; a certain amount of cooling water is stored in the pressure accumulation box, high-pressure nitrogen is arranged in the pressure accumulation box to maintain pressure, and the outlet of the pressure accumulation box is connected to a starting water supply main pipe through an electric valve.

Description

Passive water replenishing system of steam generator for passive nuclear power plant

Technical Field

The invention relates to a passive water replenishing system of a steam generator for a passive nuclear power plant, wherein the passive nuclear power plant refers to a nuclear power plant adopting the technologies of AP1000, CAP1400 and the like.

Background

After the reactor is shut down, the heat generated by fission reaction caused by neutrons in a short period of time, decay of fission products and the like still needs to be discharged in a long period of time, otherwise, the serious accident of coolant boiling and even core melting can be caused. In the design of a pressurized water reactor nuclear power plant, a steam generator is supplemented with water in an active mode, and under the condition that power supply is guaranteed, a water supply pump drives the secondary side of the steam generator to supply water for forced circulation, so that the waste heat of a reactor core is led out and sent to a final hot trap.

In nuclear power plants such as AP1000, CAP1400, etc., the

steam generators

15 and 16 are supplied with water and maintained at a level by a startup water supply system under certain operating conditions. If the liquid level is reduced to a certain setting value due to the fact that the liquid level cannot be maintained successfully, a passive core cooling system of the power plant is started to discharge the core decay heat in a passive mode in an emergency mode. The startup of the passive core cooling system is limited in the service life of the power plant, so that unnecessary startup is reduced as much as possible.

As shown in fig. 1, two startup water feed pumps 2 and 3 suck water from a condensate tank 1, respectively flow through check valves 4 and 5 and isolation valves 6 and 7, and then are collected in a startup water feed main pipe 8, and flow through startup water feed adjusting valves 9 and 10, startup water feed check valves 11 and 12, and startup water

feed isolation valves

13 and 14, and then supply water to two

steam generators

15 and 16.

Disclosure of Invention

The invention aims to solve the technical problems that two starting water-feeding pumps in the prior art are electric pumps, the operation needs the support of an alternating current power supply, and under the whole-plant power-off working condition (the failure of a standby diesel generating set due to the superposition of an external alternating current power supply), the starting water-feeding pumps cannot be started, and a starting water-feeding system cannot maintain the liquid level of a steam generator, so that a passive core cooling system is started.

In order to solve the technical problems, the technical scheme of the invention provides a passive water replenishing system of a steam generator for a passive nuclear power plant, which comprises a starting water supply system, wherein the starting water supply system comprises two starting water supply pumps, the two starting water supply pumps suck water from a condensation water tank, the water is collected to a starting water supply main pipe after flowing through corresponding check valves and isolation valves respectively, and then the water is supplied to the two steam generators after flowing through corresponding starting water supply regulating valves, starting water supply check valves and starting water supply isolation valves respectively;

the system is characterized by further comprising a steam generator passive water replenishing system on the basis of starting a water supply system, wherein the steam generator passive water replenishing system comprises a heat exchanger and a pressure accumulation box, the heat exchanger is arranged in a condensation water tank, the bottom elevation of the condensation water tank is higher than the top elevation of the steam generator, a steam pipeline at the inlet of the heat exchanger is connected with a main steam pipeline of the steam generator, and an outlet pipeline of the heat exchanger is connected with a starting water supply main pipe; a certain amount of cooling water is stored in the pressure accumulation box, high-pressure nitrogen is stored in the pressure accumulation box to maintain pressure, and the outlet of the pressure accumulation box is connected to a starting water supply main pipe through an electric valve.

Wherein, a pneumatic valve is arranged on the outlet pipeline of the heat exchanger.

The invention has the advantages that:

1. when a secondary loop water supply system of the passive pressurized water reactor nuclear power plant breaks down, the liquid level of the steam generator is maintained through the passive water supply system, the waste heat of the reactor core is led out, the dependence on a passive reactor core cooling system is reduced, unnecessary starting of the passive reactor core cooling system is reduced, and the starting times are reduced.

2. The heat exchanger and the pressure storage box are automatically put into operation, so that the possibility of human error is reduced.

3. The reliability of the water supply of the two loops is improved, and the damage probability of the reactor core and the probability of releasing a large amount of radioactivity to the environment are reduced.

Drawings

FIG. 1 is a prior art startup water supply system;

reference numbers in the figures: the system comprises a condensation water tank 1, a starting feed pump 2, a starting feed pump 3, a check valve 4, a check valve 5, an isolation valve 6, an isolation valve B7, a starting feed main pipe 8, a starting feed adjusting valve A9, a starting feed adjusting valve 10, a check valve 11, a check valve 12, a starting feed isolation valve 13, a starting feed isolation valve 14, a steam generator 15, a steam generator 16, a steam isolation valve 17 and a steam isolation valve 18;

FIG. 2 is a schematic view of an improved passive water replenishment system for a steam generator according to the present invention;

reference numbers in the figures: the system comprises a condensation water tank 1, a starting feed water pump 2, a starting feed water pump 3, a check valve 4, a check valve 5, an isolation valve 6, an isolation valve B7, a starting feed water main pipe 8, a starting feed water adjusting valve 9, a starting feed water adjusting valve 10, a check valve 11, a check valve 12, a starting feed water isolation valve 13, a starting feed water isolation valve 14, a steam generator 15, a steam generator 16, a steam isolation valve 17, a steam isolation valve 18, a pressure storage tank 21, an isolation valve 22, an isolation valve 31, a heat exchanger 32, an air-operated valve 33 and a check valve 34.

Detailed Description

In order to make the invention more comprehensible, preferred embodiments are described in detail below with reference to the accompanying drawings.

Examples

In the embodiment, a passive water replenishing system of the steam generator is additionally arranged on the basis of starting the water supply system, as shown in figure 2.

1. The condensation water tank 1 is placed at a high position, and the elevation of the bottom of the water tank is at least higher than the elevation of the top of the steam generator.

2. A heat exchanger 32 is arranged in the condensation water tank 1, a steam pipeline at the inlet of the heat exchanger 32 is connected with main steam pipelines of the

steam generators

15 and 16, and an outlet pipeline of the heat exchanger is connected with a starting water supply main pipe 8.

3. The pressure accumulation box 21 is additionally arranged, a certain amount of cooling water is stored in the pressure accumulation box, the water quality is consistent with that of the condensation water tank, and the pressure of the condensation water tank is maintained by high-pressure nitrogen. In addition, an electrically operated valve 22 is provided at the outlet of the accumulator tank, as shown.

When the liquid levels of the

steam generators

15 and 16 are lower than a certain set value and the water supply provided by the electric starting water supply pumps 2 and 3 is lost (under the whole plant power-off working condition) or is expected to be lost (the external alternating current power supply is lost and the standby diesel generating set is about to stop running), the

steam isolation valves

17 and 18 are closed in time, the pneumatic valve 33 is opened, the heat exchanger 32 is put into operation, so that condensed water after steam condensation is injected into the two

steam generators

15 and 16 again through the starting water supply main pipe 8, heat is absorbed for vaporization, the decay heat source is continuously led out to the condensation water tank 1, and meanwhile, the water content in the whole closed loop is kept unchanged. In addition, according to the change of the liquid level of the steam generator, the electric valve 22 is automatically opened, the high-pressure nitrogen in the pressure accumulation tank 21 provides driving force, cooling water is provided for the

steam generators

15 and 16, and the liquid level of the steam generators is increased or maintained. The aim of avoiding the startup of the passive core cooling system as much as possible is fulfilled.

In contrast to other inventions, the present invention arranges the heat exchanger in the existing condensation tank 1 of the passive nuclear power plant. In the case of unavailable electric pump, after natural circulation of steam-condensed water is established, decay heat can be led out in a passive mode. In addition, the natural circulation is slow to establish, and when the natural circulation is established, the liquid level of the steam generator is probably reduced to a certain setting value, the passive core cooling system is automatically started, and the aim of avoiding the start of the passive core cooling system cannot be achieved. To solve this problem, a pressure accumulator tank 25 is also provided in this patent application, which provides a short supply of water to the steam generator before the natural circulation of steam-condensate is established, using compressed nitrogen.

Claims

1. A steam generator passive water replenishing system for a passive nuclear power plant comprises a starting water supply system, wherein the starting water supply system comprises two starting water supply pumps, the two starting water supply pumps suck water from a condensation water tank, respectively flow through corresponding check valves and isolation valves and then are collected to a starting water supply main pipe, and then respectively flow through corresponding starting water supply regulating valves, starting water supply check valves and starting water supply isolation valves to supply water to two steam generators; the system is characterized by further comprising a steam generator passive water replenishing system on the basis of starting a water supply system, wherein the steam generator passive water replenishing system comprises a heat exchanger and a pressure accumulation box, the heat exchanger is arranged in a condensation water tank, the bottom elevation of the condensation water tank is higher than the top elevation of the steam generator, a steam pipeline at the inlet of the heat exchanger is connected with a steam generator and a main steam pipeline, and an outlet pipeline of the steam generator is connected with a starting water supply main pipe; a certain amount of cooling water is stored in the pressure accumulation box, high-pressure nitrogen is arranged in the pressure accumulation box to maintain pressure, and the outlet of the pressure accumulation box is connected to a starting water supply main pipe through an electric valve.

2. The steam generator passive water replenishment system for a passive nuclear power plant according to claim 1 wherein a pneumatic valve is provided on the heat exchanger outlet line.