A forced cooling system for sodium-cooled fast reactor after losing all feed water

Abstract

The invention discloses a forced cooling system after a sodium-cooled fast reactor loses all its feed water. The outlet of an auxiliary boiler is connected to the inlet of an auxiliary steam system. The outlet of the auxiliary steam system is divided into two paths, one of which is connected to the inlet of a startup and shutdown cooling system, and the other is connected to a bypass system via a main steam system. A pipeline between the bypass system and the main steam system is connected to one end of a superheater outlet valve group, and the other end of the superheater outlet valve group is connected to an atmospheric release valve group via a superheater. The outlet of the startup and shutdown cooling system is divided into two paths, one of which is connected to a pipeline between the superheater and the atmospheric release valve group, and the other is connected to a heat absorption side of an evaporator. The system can avoid the problems of low waste heat discharge rate and design redundancy when a non-kinetic waste heat discharge system discharges waste heat from a core.

Description

Technical Field

[0001] The invention belongs to the field of nuclear reactor accident shutdown cooling, and relates to a forced cooling system after a sodium-cooled fast reactor loses all its feed water. Background Art

[0002] After the three-circuit sodium-cooled fast reactor loses all its feedwater cooling, the reactor automatically shuts down and relies on the passive residual heat removal system in the primary sodium pool to discharge the core residual heat into the atmosphere. The primary passive residual heat removal system has a redundant design, but has the following shortcomings: lack of diversity design, common mode failure of redundant design is one of the problems that need to be avoided in accident safety analysis; natural circulation has low heat exchange efficiency and low residual heat removal rate compared to forced circulation. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a forced cooling system for a sodium-cooled fast reactor after the loss of all feed water. The system can avoid the problems of low waste heat removal rate and design redundancy when the non-kinetic waste heat removal system discharges the core waste heat.

[0004] To achieve the above-mentioned purpose, the forced cooling system of the sodium-cooled fast reactor after losing all feed water of the present invention comprises an auxiliary boiler, an auxiliary steam system, a first isolation valve, a second isolation valve, a startup and shutdown cooling system, a main steam system, a bypass system and a plurality of evaporator / superheater modules;

[0005] Each evaporator / superheater module includes a superheater outlet valve group, a superheater, an atmospheric release valve group, an evaporator and an evaporator inlet valve group;

[0006] The outlet of the auxiliary boiler is connected with the inlet of the auxiliary steam system. The outlet of the auxiliary steam system is divided into two routes, one of which is connected with the inlet of the startup and shutdown cooling system, and the other is connected with the bypass system through the main steam system. The pipeline between the bypass system and the main steam system is connected with one end of the superheater outlet valve group, and the other end of the superheater outlet valve group is connected with the atmospheric release valve group through the superheater. The outlet of the startup and shutdown cooling system is divided into two routes, one of which is connected with the pipeline between the superheater and the atmospheric release valve group, and the other is connected with the heat absorption side of the evaporator.

[0007] The outlet of the auxiliary steam system is connected to the main steam system through the first isolation valve.

[0008] The outlet of the auxiliary steam system is connected to the startup and shutdown cooling system through the second isolation valve.

[0009] The external water supply system is connected to the inlet of the evaporator.

[0010] The external water supply system is connected to the inlet of the evaporator through the evaporator inlet valve group.

[0011] When a loss of feedwater accident occurs, the reactor is shut down, the evaporator inlet valve group is automatically closed to isolate the feedwater system from the evaporator / superheater module, the auxiliary boiler is started, and the steam generated by the auxiliary boiler is supplied to the auxiliary steam system.

[0012] When the circulating water system is available, the steam in the auxiliary steam system enters the startup and shutdown cooling system, and then enters the superheater, where it absorbs the heat of metallic sodium for heat exchange and temperature increase. The heated steam flows through the superheater outlet valve group into the bypass system for temperature and pressure reduction, and then enters the condenser. At the same time, the first isolation valve is closed to isolate the auxiliary steam system from the main steam system, and the atmospheric release valve group is in a closed state.

[0013] When the circulating water system is unavailable, the second isolation valve is closed to isolate the auxiliary steam system and the startup and shutdown cooling system, the bypass system is closed, and the steam output from the auxiliary steam system enters the main steam system, and then enters the superheater after passing through the superheater outlet valve group, where it absorbs the heat of metallic sodium for heat exchange and temperature increase. The heated steam is discharged to the atmosphere through the atmospheric release valve group.

[0014] The present invention has the following beneficial effects:

[0015] The forced cooling system of the sodium-cooled fast reactor after losing all the feed water of the present invention adopts an active cooling and heat exchange cooling method during specific operation, uses auxiliary steam with lower parameters generated by an auxiliary boiler, passes it into a superheater to absorb the heat of the metallic sodium for heat exchange and heating, and then sends it into a bypass exhaust system for cooling and pressure reduction, or directly discharges it into the atmosphere through an atmospheric release valve group, thereby avoiding the problems of low waste heat discharge rate and design redundancy when the non-kinetic waste heat discharge system discharges the waste heat of the core, avoiding abnormalities caused by common mode failures, improving the fault safety of the unit design, and at the same time improving the waste heat discharge rate of the first and second loops of the sodium-cooled fast reactor, and no additional equipment is required, and the equipment does not need to be operated in a mode exceeding the design parameters, and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the structure of the present invention.

[0017] Among them, 1 is the auxiliary boiler, 2 is the auxiliary steam system, 3 is the main steam system, 4 is the superheater outlet valve group, 5 is the superheater, 6 is the atmospheric release valve group, 7 is the evaporator; 8 is the evaporator inlet valve group, 9 is the startup and shutdown cooling system, 10 is the evaporator / superheater module, and 11 is the bypass system. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only an embodiment of a part of the present invention, not all embodiments, and is not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concepts disclosed in the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0019] The accompanying drawings show schematic diagrams of structures according to embodiments disclosed in the present invention. These figures are not drawn to scale, and some details are magnified and some details may be omitted for the purpose of clear expression. The shapes of various regions and layers shown in the figures and the relative sizes and positional relationships therebetween are only exemplary, and may deviate in practice due to manufacturing tolerances or technical limitations, and those skilled in the art may additionally design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0020] refer to Figure 1 The forced cooling system after the sodium-cooled fast reactor loses all feed water of the present invention comprises an auxiliary boiler 1, an auxiliary steam system 2, a first isolation valve, a second isolation valve, a startup and shutdown cooling system 9, a main steam system 3, a bypass system 11 and a plurality of evaporator / superheater modules 10;

[0021] Each evaporator / superheater module 10 includes a superheater outlet valve group 4, a superheater 5, an atmospheric release valve group 6, an evaporator 7 and an evaporator inlet valve group 8;

[0022] The outlet of the auxiliary boiler 1 is connected to the inlet of the auxiliary steam system 2. The outlet of the auxiliary steam system 2 is divided into two routes, one of which is connected to the inlet of the startup and shutdown cooling system 9 through the second isolation valve, and the other is connected to the bypass system 11 through the first isolation valve and the main steam system 3. The pipeline between the bypass system 11 and the main steam system 3 is connected to one end of the superheater outlet valve group 4, and the other end of the superheater outlet valve group 4 is connected to the atmosphere release valve group 6 through the superheater 5. The outlet of the startup and shutdown cooling system 9 is divided into two routes, one of which is connected to the pipeline between the superheater 5 and the atmosphere release valve group 6, and the other is connected to the heat absorption side of the evaporator 7. The external water supply system is connected to the inlet of the evaporator 7 through the evaporator inlet valve group 8.

[0023] The working process of the present invention is:

[0024] When a loss of feed water accident occurs, the reactor is shut down and the evaporator inlet valve group 8 is automatically closed to isolate the feed water system from the evaporator / superheater module 10. The auxiliary boiler 1 is started and the 2.1 MPa, 280°C steam generated by the auxiliary boiler 1 is supplied to the auxiliary steam system 2.

[0025] When the circulating water system is available, the steam in the auxiliary steam system 2 enters the startup and shutdown cooling system 9, and then enters the superheater 5, where it absorbs the heat of the metallic sodium for heat exchange and temperature increase. The heated steam flows through the superheater outlet valve group 4 into the bypass system 11 for temperature and pressure reduction, and then enters the condenser. At the same time, the first isolation valve is closed to isolate the auxiliary steam system 2 from the main steam system 3, and the atmospheric release valve group 6 is in a closed state.

[0026] When the circulating water system is unavailable, the second isolation valve is closed to isolate the auxiliary steam system 2 and the startup and shutdown cooling system 9, the bypass system 11 is closed, and the steam output from the auxiliary steam system 2 enters the main steam system 3, and then enters the superheater 5 after passing through the superheater outlet valve group 4, and absorbs the heat of the metallic sodium in the superheater 5 for heat exchange and temperature increase. The heated steam is discharged to the atmosphere through the atmospheric release valve group 6.

[0027] During the forced circulation cooling process of the three circuits, the sodium pumps of the first and second circuits maintain a low-speed operation state, which enhances the heat exchange capacity between the three circuits while reducing the heat input brought by the sodium pumps. At the same time, as the temperature of the metallic sodium in the first and second circuits of the reactor gradually decreases, the auxiliary steam supply temperature and flow rate are also gradually adjusted and reduced to achieve forced cooling of the sodium-cooled fast reactor after the loss of all feed water.

Claims

1. A forced cooling system for a sodium-cooled fast reactor after losing all feed water, characterized in that: It comprises an auxiliary boiler (1), an auxiliary steam system (2), a first isolation valve, a second isolation valve, a startup and shutdown cooling system (9), a main steam system (3), a bypass system (11) and a plurality of evaporator / superheater modules (10); Each evaporator / superheater module (10) comprises a superheater outlet valve group (4), a superheater (5), an atmospheric release valve group (6), an evaporator (7) and an evaporator inlet valve group (8); The outlet of the auxiliary boiler (1) is connected to the inlet of the auxiliary steam system (2). The outlet of the auxiliary steam system (2) is divided into two paths, one of which is connected to the inlet of the startup and shutdown cooling system (9), and the other is connected to the bypass system (11) through the main steam system (3). The pipeline between the bypass system (11) and the main steam system (3) is connected to one end of the superheater outlet valve group (4), and the other end of the superheater outlet valve group (4) is connected to the atmosphere release valve group (6) through the superheater (5). The outlet of the startup and shutdown cooling system (9) is divided into two paths, one of which is connected to the pipeline between the superheater (5) and the atmosphere release valve group (6), and the other is connected to the heat absorption side of the evaporator (7).

2. The forced cooling system for a sodium-cooled fast reactor after losing all feed water according to claim 1, characterized in that: The outlet of the auxiliary steam system (2) is connected to the main steam system (3) via a first isolation valve.

3. The forced cooling system for a sodium-cooled fast reactor after losing all feed water according to claim 1, characterized in that: The outlet of the auxiliary steam system (2) is connected to the startup and shutdown cooling system (9) via a second isolation valve.

4. The forced cooling system for a sodium-cooled fast reactor after losing all feed water according to claim 1, characterized in that: The external water supply system is connected to the inlet of the evaporator (7).

5. The forced cooling system for a sodium-cooled fast reactor after losing all feed water according to claim 4, characterized in that: The external water supply system is connected to the inlet of the evaporator (7) through the evaporator inlet valve group (8).

6. The forced cooling system for a sodium-cooled fast reactor after losing all feed water according to claim 5, characterized in that: When a loss of feed water accident occurs, the reactor is shut down, the evaporator inlet valve group (8) is automatically closed to isolate the feed water system from the evaporator / superheater module (10), the auxiliary boiler (1) is started, and the steam generated by the auxiliary boiler (1) is supplied to the auxiliary steam system (2).

7. The forced cooling system for a sodium-cooled fast reactor after losing all feed water according to claim 1, characterized in that: When the circulating water system is available, the steam in the auxiliary steam system (2) enters the startup and shutdown cooling system (9), and then enters the superheater (5), where it absorbs the heat of the metallic sodium for heat exchange and temperature increase. The heated steam flows through the superheater outlet valve group (4) into the bypass system (11) for temperature reduction and pressure reduction, and then enters the condenser. At the same time, the first isolation valve is closed to isolate the auxiliary steam system (2) from the main steam system (3), and the atmospheric release valve group (6) is in a closed state.

8. The forced cooling system for a sodium-cooled fast reactor after losing all feed water according to claim 1, characterized in that: When the circulating water system is unavailable, the second isolation valve is closed to isolate the auxiliary steam system (2) and the startup and shutdown cooling system (9), the bypass system (11) is closed, and the steam output from the auxiliary steam system (2) enters the main steam system (3), then passes through the superheater outlet valve group (4) and enters the superheater (5), where it absorbs the heat of the metallic sodium for heat exchange and temperature increase. The heated steam is discharged to the atmosphere through the atmosphere release valve group (6).

Images