阅读说明：本技术 一种小型压水反应堆及安全壳长期非能动热量排出系统 (Small pressurized water reactor and long-term passive heat discharge system of containment ) 是由 曾未 宋丹戎 秦忠 江光明 许斌 钟发杰 陈智 李庆 任云 邓坚 邱志方 曾畅 于 2020-04-16 设计创作，主要内容包括：本发明属于反应堆安全技术领域,具体涉及一种小型压水反应堆及安全壳长期非能动热量排出系统。该系统包括非能动余排换热器、低压安注管线、再循环管线、低压安注水箱、安全壳地坑、安全壳和冷凝水收集装置,非能动余排换热器浸没于低压安注水箱中,低压安注箱通过低压安注管线与反应堆下降段相连,安全壳地坑通过再循环管线与反应堆下降段相连。该发明使得小型压水反应堆的安全性提升到了全新的高度,仅仅依赖空气,就可保证反应堆余热长期有效,从设计上实现固有安全,可以取消场外应急,经济性和厂址适应性都将获得极大提升。(The invention belongs to the technical field of reactor safety, and particularly relates to a small pressurized water reactor and a long-term passive heat discharge system of a containment. The system comprises a passive surplus heat exchanger, a low-pressure safety injection pipeline, a recycling pipeline, a low-pressure safety injection water tank, a containment pit, a containment and a condensate water collecting device, wherein the passive surplus heat exchanger is immersed in the low-pressure safety injection water tank, the low-pressure safety injection water tank is connected with a reactor descending section through the low-pressure safety injection pipeline, and the containment pit is connected with the reactor descending section through the recycling pipeline. The invention improves the safety of the small pressurized water reactor to a brand new height, can ensure the long-term effectiveness of the waste heat of the reactor only by relying on air, realizes the inherent safety from the design, can cancel the off-site emergency, and greatly improves the economy and the plant site adaptability.)

1. A small-size pressurized water reactor and containment long-term passive heat discharge system which is characterized in that: the system comprises a passive surplus heat exchanger (4), a low-pressure safety injection pipeline (5), a recirculation pipeline (6), a low-pressure safety injection water tank (7), a containment pit (8), a containment (9) and a condensate water collecting device (10), wherein the passive surplus heat exchanger (4) is immersed in the low-pressure safety injection water tank (7), the low-pressure safety injection water tank (7) is connected with a descending section of a reactor (1) through the low-pressure safety injection pipeline (5), and the containment pit (8) is connected with the descending section of the reactor (1) through the recirculation pipeline (6).

2. The small scale pressurized water reactor and containment long term passive heat removal system of claim 1, wherein: the condensed water collecting device (10) is tightly attached to the inner surface of the upper part of the containment vessel (9).

3. The small scale pressurized water reactor and containment long term passive heat removal system of claim 2, wherein: the condensed water collecting device (10) is connected with the containment (9) in a welding mode.

4. The small scale reactor and containment long term passive heat removal system of claim 3, wherein: the passive residual heat exchanger (4), the low-pressure safety injection pipeline (5), the recirculation pipeline (6), the low-pressure safety injection water tank (7), the containment pit (8) and the condensed water collecting device (10) are uniformly distributed in the containment (9).

5. The small scale reactor and containment long term passive heat removal system of claim 4, wherein: and two ends of the passive residual heat exchanger (4) are respectively connected with the cold end and the hot end of the reactor (1).

6. The small scale reactor and containment long term passive heat removal system of claim 5, wherein: and two ends of the passive residual heat removal heat exchanger (4) are connected with a water supply pipeline and a steam pipeline of the steam generator (3).

7. The small scale reactor and containment long term passive heat removal system of claim 6, wherein: when a non-loss-of-coolant accident occurs, heat is introduced into the low-pressure safety injection water tank (7) through the passive exhaust heat exchanger (4), heat of the reactor (1) is taken away through water heating and evaporation in the low-pressure safety injection water tank (7), steam generated by evaporation partially flows back to the low-pressure safety injection water tank (7) through the condensed water collecting device (10) after being cooled through air outside the containment (9), the working time of the passive exhaust system is prolonged, closed circulation is formed, and the heat of the containment is transferred to air outside the containment through the wall surface of the containment by using natural principles such as radiation and convection, so that the heat is discharged into the atmosphere of a final heat trap.

8. The small scale reactor and containment long term passive heat removal system of claim 7, wherein: in the cooling process of the reactor core (2) after a loss of coolant accident, the water level of the low-pressure safety injection water tank (7) is gradually lowered, the water level of the containment sump (8) is raised until the water level of the low-pressure safety injection water tank (7) is balanced with the water level of the containment sump (8), water in the containment sump (8) is injected into the reactor core (2) through the recirculation pipeline (6), the water injected into the reactor core is heated and evaporated and then enters the containment (9), steam flows upwards and is condensed by the air outside the containment (9) and then flows back along the wall surface of the containment and finally is collected into the containment sump (8), the amount of water submerged in the containment sump (8) is maintained until the balanced water level is unchanged, and therefore long-term cooling of the reactor core (2).

9. The small scale reactor and containment long term passive heat removal system of claim 8, wherein: in the later stage of alleviating non-loss of coolant accident, if the power does not recover all the time, the water content of the low-pressure safety injection water tank (7) is insufficient, so that the passive surplus heat exchanger (4) is exposed, a pressure relief mode is adopted, the flow of alleviating loss of coolant accident is switched to after the pressure of a primary loop is reduced, and the long-term passive heat derivation without the power is realized.

Technical Field

The invention belongs to the technical field of reactor safety, and particularly relates to a small pressurized water reactor and a long-term passive heat discharge system of a containment.

Background

The long-term effective derivation of reactor waste heat is one of three safety functions of a reactor, a waste heat discharge system is a special safety facility for dealing with design benchmark accidents and serious accidents of the reactor, the conventional nuclear reactor safety system widely adopts passive emergency core cooling and passive waste heat discharge systems to improve the reliability of the system, but for a large pressurized water reactor, because the residual heat level of the reactor is high, the air cooling is difficult to directly utilize after an accident, a water source with large loading is generally required to be used as a final heat sink, and the final heat sink water source loading is determined by satisfying 72-hour passive waste heat derivation. For a small reactor, the residual heat of the reactor is small, so that the heat in the containment can be cooled and exhausted through the air outside the containment by using the wall surface of the containment as a heat exchanger through the containment with proper size. At present, the international small reactor design mostly continues the mode that a cooling water source is adopted as a final hot trap in a large pressurized water reactor, and the design of the final hot trap water source is not cancelled according to the characteristics of the small pressurized water reactor. Therefore, a small pressurized water reactor and a long-term passive heat removal system for a containment vessel are needed to be designed so as to improve the inherent safety of the reactor and solve the defects of the prior art.

Disclosure of Invention

The invention aims to provide a small pressurized water reactor and a long-term passive heat discharge system of a containment vessel aiming at the defects of the prior art, which fully utilize the characteristic of low residual heat level of the core of the small pressurized water reactor, utilize the air naturally existing in the medium-scale containment vessel and the outer wall surface thereof to realize the passive discharge of the residual heat of the reactor for a long time, improve the inherent safety of the small pressurized water reactor, simplify a safety system and improve the economical efficiency.

The technical scheme of the invention is as follows:

the system comprises a passive surplus heat exchanger, a low-pressure safety injection pipeline, a recirculation pipeline, a low-pressure safety injection water tank, a containment pit, a containment and a condensate water collecting device, wherein the passive surplus heat exchanger is immersed in the low-pressure safety injection water tank, the low-pressure safety injection tank is connected with a reactor descending section through the low-pressure safety injection pipeline, and the containment pit is connected with the reactor descending section through the recirculation pipeline.

The condensed water collecting device is tightly attached to the inner surface of the upper part of the containment.

The condensed water collecting device is connected with the containment in a welding mode.

The passive residual heat exchanger, the low-pressure safety injection pipeline, the recirculation pipeline, the low-pressure safety injection water tank, the containment pit and the condensate water collecting device are uniformly distributed in the containment.

And two ends of the passive residual heat exchanger are respectively connected with the cold end and the hot end of the reactor.

And two ends of the passive exhaust heat exchanger are connected with a water supply pipeline and a steam pipeline of the steam generator, and the reactor core waste heat is led out through the secondary side of the steam generator.

When a non-loss-of-coolant accident occurs, heat is introduced into the low-pressure safety injection water tank through the passive surplus heat exchanger, heat of a reactor is taken away through water heating and evaporation in the low-pressure safety injection water tank, steam generated by evaporation partially flows back to the low-pressure safety injection water tank through the condensed water collecting device after being cooled by air outside the containment, the working time of the passive surplus heat exhaust system is prolonged, closed circulation is formed, heat of the containment is transferred to air outside the containment through the wall surface of the containment by using natural principles such as radiation and convection, and therefore the heat is discharged into the atmosphere of a final heat trap.

In the reactor core cooling process after a loss of coolant accident occurs, the water level of the low-pressure safety injection water tank gradually drops, the water level of the containment sump rises until the water level of the low-pressure safety injection water tank is balanced with the water level of the containment sump, water in the containment sump is injected into the reactor core through a recirculation pipeline, the water injected into the reactor core is heated and evaporated and then enters the containment, steam flows upwards, is condensed by air outside the containment and then flows back along the wall surface of the containment, and finally is collected into the containment sump, the water amount submerged in the containment sump is maintained until the balanced water level is unchanged, and therefore long-term cooling of the reactor core is achieved.

In the later stage of alleviating non-loss of coolant accident, if the power does not recover all the time, the water charge of the low-pressure safety water injection tank is insufficient, so that the passive surplus heat exchanger is exposed, a pressure relief mode is adopted, the loss of coolant accident alleviating process is switched to after the pressure of a primary loop is reduced, and the passive heat derivation without the power for a long time is realized.

The invention has the following beneficial effects:

the invention has two main beneficial effects, firstly, in the aspect of safety, the design enables the safety of the small pressurized water reactor to be improved to a brand new height, namely, the safety of the small pressurized water reactor is improved to a very simple design, the waste heat of the reactor can be ensured to be effective for a long time only by relying on air without a power supply, and the inherent safety is realized in the design. Due to the fact that the safety performance is changed, the design of the safety system of the small-sized reactor can be greatly simplified, off-site emergency can be eliminated, and the economy and the adaptability of a plant site are greatly improved. The benefits of the two aspects play an important role in popularization and application of the small-scale stacking technology.

Drawings

FIG. 1 is a schematic structural view of a small pressurized water reactor and containment long term passive heat removal system designed in accordance with the present invention;

wherein: 1-reactor, 2-reactor core, 3-steam generator, 4-passive residual heat exchanger, 5-low pressure safety injection pipeline, 6-recirculation pipeline, 7-low pressure safety injection water tank, 8-containment pit, 9-containment and 10-condensed water collecting device

Detailed Description

The present technology is further described below:

as shown in figure 1, the system comprises a passive surplus heat exchanger 4, a low-pressure safety injection pipeline 5, a recirculation pipeline 6, a low-pressure safety injection water tank 7, a containment pit 8, a containment 9 and a condensate water collecting device 10, wherein the outer wall surface of the containment 9 is used for air cooling, steam on the inner wall surface is used for condensation and backflow, a cooling water source is not needed to be used as a final heat sink after an accident, and only air is used as the final heat sink all the time.

After a reactor 1 is shut down, waste heat is stored in a reactor core 2, the reactor core 2 is contained by a pressure vessel of the reactor 1, a passive residual heat exchanger 4 is immersed in a low-pressure safety injection water tank 7, two ends of the passive residual heat exchanger 4 are respectively connected with a cold end and a hot end of the reactor 1, the waste heat of the reactor core 2 is led out to the low-pressure safety injection water tank 7 through the passive residual heat exchanger 4, the low-pressure safety injection water tank 7 is connected with a descending section of the reactor 1 through a low-pressure safety injection pipeline 5, a containment pit 8 is connected with the descending section of the reactor 1 through a recirculation pipeline 6, all components are uniformly distributed in a containment vessel 9, and a condensate water collecting device 10 is tightly attached to the inner surface of the upper part of the containment vessel 9 and is connected with.

The invention is based on a typical integrated reactor and can also be popularized to reactors of other arrangement types.

Two ends of the passive exhaust heat exchanger 4 are connected with a water supply pipeline and a steam pipeline of the steam generator 3, and the waste heat of the reactor core is led out through the secondary side of the steam generator 3.

When a non-loss-of-coolant accident occurs, heat is conducted into the low-pressure safety injection water tank 7 through the passive surplus heat exchanger 4, heat of the reactor 1 is taken away through water heating and evaporation in the low-pressure safety injection water tank 7, steam generated by evaporation partially flows back to the low-pressure safety injection water tank 7 through the condensed water collecting device 10 after being cooled through air outside the containment 9, the working time of the passive surplus heat exhaust system is prolonged, closed circulation is formed, heat of the containment 9 is transmitted to air outside the containment 9 through the wall surface of the containment 9 through natural principles of radiation, convection and the like, and therefore the heat is exhausted into the atmosphere of a final heat sink. And under the condition of ensuring higher recovery rate of the condensed water, the safety of the reactor core 2 for a longer period is ensured. If the water level of the low-pressure safety injection water tank 7 is not recovered after the water level is lower than a certain limit value, the automatic pressure relief system of the reactor is automatically started, and then the process of relieving the loss of coolant accident is switched to realize the long-term cooling of the reactor core.

In the cooling process of the reactor core 2 after a loss of coolant accident, the water level of the low-pressure safety injection water tank 7 is gradually reduced, the water level of the containment pit 8 is increased until the water level of the low-pressure safety injection water tank 7 is balanced with the water level of the containment pit 8, and then water in the containment pit 8 is injected into the reactor core 2 through the recirculation pipeline 6. Part of the upward flow is condensed by air outside the containment 9 and then flows back to be finally collected to the containment pit 8, and the water amount submerged in the containment pit 8 is maintained until the balance water level is unchanged, so that the long-term cooling of the reactor core 2 is realized.

This small-size pressurized-water reactor and long-term passive heat discharge system of containment, in the later stage is alleviated to the non-loss of coolant accident, if the power does not resume all the time, low pressure safety injection water tank 7 water charge is not enough, leads to the passive surplus heat exchanger 4 of arranging to expose, then takes the release mode, changes over into the loss of coolant accident after reducing a return circuit pressure and alleviates the flow, realizes the long-term passive heat derivation that does not need the power.

The present invention has been described in detail with reference to the embodiments, but the present invention is not limited to the embodiments, and various changes can be made without departing from the gist of the present invention within the knowledge of those skilled in the art. The prior art can be adopted in the content which is not described in detail in the invention.