阅读说明：本技术 一种核电厂新型自动卸压系统及方法 (Novel automatic pressure relief system and method for nuclear power plant ) 是由 夏栓 王炜波 向文娟 吴辉平 李东祚 刘冰 刘佳 刘洁 杨小杰 徐进 武心壮 于 2021-05-31 设计创作，主要内容包括：本发明涉及核电厂蒸汽自卸压系统技术领域,具体地说是非能动设计的一种核电厂新型自动卸压系统及方法,包括稳压器、ADS隔离阀、喷射器、位于安全壳内的高位水箱、鼓泡器、低位水箱、ADS排放管道以及吸水管道；稳压器的出口端采用ADS排放管道依次连接ADS隔离阀、喷射器的一个进水口、鼓泡器；鼓泡器位于高位水箱内,低位水箱采用吸水管道连接喷射器的另一个进水口。本发明与现有技术相比,可以有效地利用蒸汽喷射时释放的能量,使原先直接排放至高位水箱内的能量被有效地利用,同时将原先低位水箱内用不到的水源抽至高位水箱,高位水箱的尺寸也可以减小,从而最大化地利用安全壳内部的布置空间,最终提升核电厂的安全性和经济性。(The invention relates to the technical field of a steam self-pressure relief system of a nuclear power plant, in particular to a novel automatic pressure relief system and a method of a nuclear power plant, which are designed in a passive mode, wherein the novel automatic pressure relief system comprises a pressure stabilizer, an ADS (automatic pressure dependent Surveillance) isolation valve, an ejector, a high-level water tank, a bubbler, a low-level water tank, an ADS discharge pipeline and a water suction pipeline, wherein the high-level water tank, the bubbler, the low-level water tank, the ADS discharge pipeline and the water suction pipeline are positioned in a containment; the outlet end of the pressure stabilizer is sequentially connected with an ADS isolation valve, a water inlet of the ejector and the bubbler by adopting an ADS discharge pipeline; the bubbler is positioned in the high-level water tank, and the low-level water tank is connected with the other water inlet of the ejector by adopting a water suction pipeline. Compared with the prior art, the invention can effectively utilize the energy released during steam injection, effectively utilize the energy originally directly discharged into the high-level water tank, simultaneously pump the water source which cannot be used in the original low-level water tank into the high-level water tank, and reduce the size of the high-level water tank, thereby maximally utilizing the arrangement space in the containment vessel and finally improving the safety and the economy of the nuclear power plant.)

1. A novel automatic pressure relief system of a nuclear power plant, which is characterized in that,

the device comprises a pressure stabilizer (1), an ADS isolation valve (2), an ejector (3), a high-level water tank (4) positioned in a containment, a bubbler (5), a low-level water tank (6), an ADS discharge pipeline (7) and a water suction pipeline (8);

the outlet end of the pressure stabilizer (1) is sequentially connected with an ADS isolating valve (2), a water inlet of the ejector (3) and the bubbler (5) by adopting an ADS discharge pipeline (7); the bubbler (5) is positioned in the high-level water tank (4), and the low-level water tank (6) is connected with the other water inlet of the ejector (3) by adopting a water suction pipeline (8).

2. The new automatic pressure relief system of nuclear power plant as claimed in claim 1, characterized in that there are several branches in parallel between said pressurizer (1) and the ejector (3), and there are two ADS isolating valves (2) in series in each branch.

3. The method of automatic pressure relief system as claimed in claim 2, wherein: when a nuclear power plant breaks the opening and loses water accident, the ADS isolation valve (2) is opened successively, high-pressure steam flows through the ejector (3) from the pressure stabilizer (1) through the ADS discharge pipeline (7), the high-pressure steam converts pressure into suction kinetic energy in the ejector (3) through the nozzle, water in the low-level water tank (6) is ejected into a suction chamber of the ejector (3) through the water suction pipeline (8) under the action of the suction kinetic energy, the water in the low-temperature water tank (6) and the high-pressure steam in the ejector (3) are mixed to form mixed liquid which is discharged out of the ejector (3) together, and then the mixed liquid is discharged into the high-level water tank (4) through the bubbler (5), so that the pressure of a reactor coolant system is reduced.

Technical Field

The invention relates to the technical field of steam automatic pressure relief systems of nuclear power plants, in particular to a novel automatic pressure relief system and a novel automatic pressure relief method of a nuclear power plant, which are passively designed.

Background

The main function of an automatic pressure relief system (ADS) is to reduce the pressure of the Reactor Coolant System (RCS) to allow safe injection into service after a loss of coolant accident at the nuclear power plant so that the core remains cool. The automatic pressure relief system of a general nuclear power plant mainly comprises an automatic pressure relief valve and related pipelines, wherein an inlet of the automatic pressure relief valve is connected with a pressure stabilizer, and an outlet of the automatic pressure relief valve is discharged to a pressure-restraining water tank or a refueling water tank.

The operation of the automatic pressure relief system is accompanied with the release of a large amount of steam waste heat, and a large amount of energy is wasted, so that a novel automatic pressure relief system is needed to be designed to effectively utilize the waste heat. Safe injection is the primary means of maintaining core cooling in nuclear power plants. The water level difference is utilized to carry out safe injection, the device has the characteristic of no need of using a pump, a fan, a diesel engine or an alternating current power supply, and is an advanced passive reactor core cooling mode. However, as the water level decreases as the injection progresses, the driving capability decreases, resulting in a decrease in the safe injection flow rate, which is detrimental to the cooling of the core.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, effectively utilize the energy released during steam injection, pump the water in the low-level water tank into the high-level water tank through the ejector and improve the capability of the high-level water tank for maintaining gravity injection; in addition, the design water content of the high-level water tank can be reduced, so that the space occupied by the high-level water tank is reduced, and the arrangement in the containment vessel is optimized.

In order to achieve the aim, the novel automatic pressure relief system of the nuclear power plant is designed, which is characterized in that,

the device comprises a pressure stabilizer, an ADS isolation valve, an ejector, a high-level water tank, a bubbler, a low-level water tank, an ADS discharge pipeline and a water suction pipeline, wherein the high-level water tank, the bubbler, the low-level water tank, the ADS discharge pipeline and the water suction pipeline are positioned in a containment;

the outlet end of the pressure stabilizer is sequentially connected with an ADS isolation valve, a water inlet of the ejector and the bubbler by adopting an ADS discharge pipeline; the bubbler is positioned in the high-level water tank, and the low-level water tank is connected with the other water inlet of the ejector by adopting a water suction pipeline.

Furthermore, a plurality of parallel branches are arranged between the voltage stabilizer and the ejector, and two ADS isolation valves connected in series are arranged in each branch.

A method of a novel automatic pressure relief system of a nuclear power plant is characterized by comprising the following steps: when a nuclear power plant has a breach loss of coolant accident, the ADS isolation valve is opened successively, high-pressure steam flows through the ejector from the pressure stabilizer through the ADS discharge pipeline, the high-pressure steam converts pressure into suction kinetic energy in the ejector through the nozzle, water in the low-level water tank is injected into a suction chamber of the ejector through the water suction pipeline under the action of the suction kinetic energy, the water in the low-temperature water tank and the high-pressure steam in the ejector are mixed to form mixed liquid, the mixed liquid is discharged out of the ejector together, and the mixed liquid is discharged into the high-level water tank through the bubbler, so that the pressure of a reactor coolant system is reduced.

Compared with the prior art, the invention can effectively utilize the energy released during steam injection, effectively utilize the energy originally directly discharged into the high-level water tank, simultaneously pump the water source which cannot be used in the original low-level water tank into the high-level water tank, and reduce the design size of the high-level water tank, thereby maximally utilizing the arrangement space in the containment, optimizing the design of the containment, and finally improving the safety and the economy of the nuclear power plant.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

The invention will now be further described with reference to the accompanying drawings.

The invention effectively utilizes the kinetic energy discharged by the automatic pressure relief system to absorb the water in the low-level water tank to the high level through the passive structural design, and simultaneously can reduce the design size of the high-level water tank.

The main design principle is as follows: an ejector 3 is added on an ADS discharge pipeline 7 at the downstream of the ADS isolation valve, the high-pressure working fluid-steam in the ADS discharge pipeline converts the pressure into kinetic energy through a nozzle of the ejector 3, the pumped fluid-water in a low-level water tank is ejected into a suction chamber of the ejector 3 due to the shearing force between the pumped fluid and the working fluid, the turbulent diffusion effect of a jet flow boundary layer enables the two fluids to exchange energy, and a mixed fluid is formed and is discharged out of the ejector 3 together. Therefore, the ejector 3 is arranged on the ADS pipeline 7, so that energy originally directly discharged into the high-level water tank 4 is effectively utilized, meanwhile, a water source in the original low-level water tank 6 is pumped into the high-level water tank 4, the injection capacity of the high-level water tank 4 is maintained, the design size of the high-level water tank 4 can be reduced, the arrangement space in the containment is utilized to the maximum degree, and the design of the containment is optimized.

Example 1

Referring to fig. 1, the novel automatic pressure relief system of the nuclear power plant is characterized by comprising a pressure stabilizer 1, an ADS isolation valve 2, an ejector 3, a high-level water tank 4 positioned in a containment, a bubbler 5, a low-level water tank 6, an ADS discharge pipeline 7 and a water suction pipeline 8;

the outlet end of the pressure stabilizer 1 is sequentially connected with an ADS isolating valve 2, a water inlet of the ejector 3 and the bubbler 5 by adopting an ADS discharge pipeline 7; the bubbler 5 is positioned in the high-level water tank 4, and the low-level water tank 6 is connected with the other water inlet of the ejector 3 by adopting a water suction pipeline 8. A plurality of parallel branches are arranged between the voltage stabilizer 1 and the ejector 3, and two ADS isolation valves 2 connected in series are arranged in each branch.

Based on the automatic pressure relief system, when a nuclear power plant has a breach water loss accident, in order to carry out step-by-step controlled pressure relief on RCS, the ADS isolation valve 2 is opened successively, high-pressure steam generated in a loop flows through the ejector 3 from the pressure stabilizer 1 through the ADS discharge pipeline 7, the high-pressure steam converts pressure into suction kinetic energy in the ejector 3 through a nozzle, water in the low-level water tank 6 is ejected into a suction chamber of the ejector 3 through the water suction pipeline 8 under the action of the suction kinetic energy, water in the low-temperature water tank 6 and the high-pressure steam in the ejector 3 are mixed to form mixed liquid which is ejected out of the ejector 3 together, and then the mixed liquid is ejected into the high-level water tank 4 through the bubbler 5, so that the pressure of a reactor coolant system is reduced.

According to the invention, through adding the ejector 3, the energy which is originally directly discharged into the high-level water tank 4 can be effectively utilized without additional kinetic energy, and meanwhile, the water source in the original low-level water tank 6 is pumped into the high-level water tank 4 to maintain the injection capacity of the high-level water tank 4, so that the design size of the high-level water tank 4 can be reduced, the arrangement space in the containment is utilized to the maximum extent, the design of the containment is optimized, the effect of effectively reducing RCS pressure is achieved, and the high-level water tank has higher application value in the design of a nuclear power plant.