JPS6244692A - Decay heat removing device for nuclear reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a decay heat removal device for a Z1 nuclear reactor, which is a safety measure equipment in the event of a total loss of AC power at a nuclear power plant.

[Technical background of the invention and its problems] When a total AC power loss event occurs during the rated operation of the nuclear reactor at a nuclear power plant, all dynamic equipment that uses AC power as a noise source stops, and the nuclear power If the power plant is ≦2, this will be one of the situations with the greatest impact. Even in such a case, in order to ensure that the safety of the nuclear power plant is not compromised, a turbine-driven Reactor Isolation Cooling System (hereinafter abbreviated as RCIC), which uses reactor steam as a driving source, is installed. do.)
is provided. Since this RCIC uses nuclear reactor steam as its source of ground motion, it is designed to be able to function even if all AC power is lost, unlike other electrically driven systems. In the configuration C2, the condensate storage ml- is shorter than the turbine-driven pump 1-.
For longer periods of time, reactor water from the stored water source is injected into the reactor from the suppression pool, making it possible to maintain the water level in the reactor even when all AC power is lost. However, if the total AC power loss becomes prolonged, the DC power used to control the RCIC will run out in a few hours, making it difficult to continue operating the RCIC, and the reactor water level will drop, causing a worst-case scenario. This would lead to core meltdown accident C2. Furthermore, even if this problem of DC power depletion could be solved by some method, assuming that all AC power continues to be lost for an extended period of time, the steam generated by the reactor's decay heat C2 will have to be released. The decay heat is transferred from the safety valve to the suppression pool of the reactor containment vessel, where it is condensed and cooled. This ζ2 causes the temperature and pressure inside the reactor containment vessel to rise, and if this state continues for a long time, the final C2 will reach the failure temperature and failure pressure of the reactor containment vessel, causing the reactor containment vessel 1 to fail. If the reactor containment vessel is damaged, the suppression pool water will rapidly boil under reduced pressure and the water level will drop, making it impossible for the RCIe pump to secure the required suction head (required NPSH) and stop it. What you end up doing C: Become. If this happens, the water level in the reactor will also decrease below the decay heat C, leading to exposure of the reactor core, which could lead to a core meltdown accident.

[Object of the Invention] The present invention has been made in view of the above-mentioned facts. At a nuclear power plant 1, a complete loss of AC power supply occurred during the rated operation of the reactor, and the reactor cooling system and emergency core cooling system If all electric core cooling functions including the residual heat removal system etc. are lost,
It is an object of the present invention to provide a decay heat removal device for a nuclear reactor that appropriately removes decay heat from a reactor core and prevents core damage due to decay heat and overtemperature damage or overpressure damage to a reactor containment vessel.

[Summary of the Invention] The present invention provides a first pipe that guides steam generated by C1 from a reactor housed in a reactor pressure vessel when all AC power is lost through a flow rate adjustment valve; A pool that condenses the released steam and leads coolant from outside the reactor building, a water storage tank that stores the condensed water condensed in this pool, and a water storage tank that leads the condensate in the condensate storage tank to raise the pressure. a pump, an upper spray pipe that leads water pressurized by the pump to an upper spray nozzle provided in an upper part C of the reactor pressure vessel, and a steam turbine directly connected to the pump;
A second pipe that branches from the first pipe and guides steam to the steam turbine via a flow rate regulating valve, and a generator that is directly connected to the steam turbine and used as a control power source after rectifying the generated current. A decay heat removal device for a nuclear reactor is characterized by:

[Embodiment of the Invention] Hereinafter, a first embodiment of the present invention will be described based on FIG. 1C. Figure 1C: The reactor pressure vessel l that houses the nuclear reactor is stored inside the reactor containment vessel 2 (-).
A water gate 10 is provided between the gas phase portion of the reactor pressure vessel 1 and a water source 9 such as pool 6 water, river water, or ground water via V+ separation valves 3 and 4 and a flow rate adjustment valve 5. Also,
A check valve 1], a pump 12, and a flow rate adjustment valve 1 as piping for supplying make-up water into the reactor pressure vessel 1 from the condensate storage tank 8.
3 to the upper spray nozzle 15ac of the reactor pressure vessel 1 via the isolation valves 14 and 15.
is provided. Further, as a steam line for driving the steam turbine 18, a steam line is connected to the steam turbine 18 from the gas phase part of the reactor pressure vessel 1 via an isolation valve 3.4 and a flow rate adjustment valve 17.
A second piping 18a leading to is provided. The steam turbine 181 is directly connected to the pump 12, and is also equipped with a small generator 19, which is used as a rectifier 20 to convert AC power into DC power. A power distribution line is provided to distribute power to a lubricating oil cooler (not shown) for the bearings of the turbine 19.

In the above configuration C unit, during the rated operation of the reactor at nuclear power plant C2, an accident occurred in which all AC power was lost in unit 1, and all electrically driven reactor cooling systems, emergency core cooling systems, and residual heat When all core cooling functions including the removal system are lost, the steam generated in the reactor pressure vessel 1 is removed from the gas phase to remove the decay heat generated in the reactor core. , 4 and adjust the flow rate regulating valve 5 to set an appropriate steam flow rate C2.

A control current power source is used for all these operations.

The extracted steam exchanges heat with the pool 6 through a heat exchange pipe 7a passing through the pool 6, becomes condensed water, and is stored in a condensate storage tank 8. The pool 6 is normally filled with fresh water to prevent corrosion of the heat exchange piping 7a, but when the temperature rises due to decay heat transfer, the water gate 10 is opened and seawater is poured into the pool 6.

River water or groundwater 9 is introduced into pool 6E.

- In order to replenish the reactor cooling water, the pump 12 draws cooling water from the water storage tank 8, and after adjusting the supply water flow noise with the flow rate adjustment valve 13 (:), it is passed through the isolation valve 14 and 15 to the upper spray nozzle 16a. The steam turbine 18 supplies cooling water into the reactor pressure vessel l.The steam turbine 18 is for driving the pump 12 and the small AC generator 19, and is used to control the flow rate of steam taken out from the gas phase part of the reactor pressure vessel 1. After adjusting the flow rate with the regulating valve 17, the steam turbine 18 is driven.The small generator 19 generates electricity.The alternating current power is exchanged to direct current using the rectifier 20, and then stored in the battery 21. It is also used as a power source for the bearing sleeve oil cooler of steam turbine 9.

Next, a second embodiment of the present invention will be described with reference to FIG. Note that in FIG. 2, the same parts as in FIG. 1 are given the same reference numerals. FIG. 2 1-7, A reactor pressure vessel 1 housing a nuclear reactor is installed within a reactor containment vessel 2. Further, from the gas phase part of the reactor pressure vessel 1, it passes through the isolation valves 3, 4 and the flow rate adjustment valve 5, through the heat exchange piping 7a in the pool 6, and then through the isolation valve 14, 15 again to the reactor. A pipe 7 leading to the liquid phase portion of the pressure vessel 1 is provided, and a water gate 10 is provided between the ZJ0 pool 6 and a water source 9 such as seawater, river water, or groundwater.

In the above configuration, when all AC power is lost, steam is taken out from the gas phase part of the reactor pressure vessel 1 via the isolation valve 3.4, and the flow rate of this steam is adjusted by the flow rate adjustment valve 5. After that, it is guided to the heat exchange piping 7a in the pool 6 and exchanges heat with the cooling water to form condensed water from the reactor pressure vessel 1 due to its own weight C2.
It is returned to the liquid phase.

In order to prevent corrosion of the heat exchange piping 7a in the pool 6, fresh water is normally stored in the pool 6. However, if the water temperature rises above the decay heat of 62, the ini will be sluice 10.
is opened, and cooling water is introduced into the pool 6 from a water source 9, which is seawater, river water, or underground water, and the pool 6 is cooled.

[Effect of the invention] As described above, the decay heat removal device C for a nuclear reactor according to the present invention
At a nuclear power plant (-), a complete loss of AC power occurred during the rated operation of the reactor, and all electrically driven reactor cooling systems, emergency core cooling systems, rapid decay heat removal systems, etc. In the event that all core cooling functions, including the
Semi-permanent operation is possible because a variety of water sources such as seawater, river water, or groundwater, which have an infinite heat capacity, are used as a heat radiation source. Therefore, it is possible to prevent core melting due to decay heat (-), damage to the child reactor pressure vessel, and damage to the reactor containment vessel, and to prevent risks to the environment.

[Brief explanation of the drawing]

FIG. 1 is a schematic system diagram showing a decay heat removal device for a nuclear reactor according to the first embodiment ζ2 of the present invention, and FIG. 2 is a schematic system diagram showing a decay heat removal device for a nuclear reactor according to the second embodiment C2 of the present invention. It is a schematic system diagram. 1... Reactor pressure vessel 5, 13.17... Flow rate adjustment valve 6... Pool 7... First piping 7a
...Heat exchange distribution W8...Condensate storage tank 9...Water source ■2...Pump 16...Upper spray piping 16a...Upper spray 18...Steam turbine 18a... Second piping 19... Small generator 22... Le IJ official load agent Patent attorney rules
Ken Chika Yudo Hirofumi Mitsumata

Claims (1)

[Claims] (1) A first channel that guides steam generated from the reactor housed in the reactor pressure vessel when all AC power is lost through a flow rate regulating valve.
a pool that condenses the steam led from this first pipe and leads coolant from outside the reactor building, a condensate storage tank that stores condensed water condensed in this pool, and a condensate storage tank that stores condensed water condensed in this pool, and A pump that guides and pressurizes condensate in a water storage tank, an upper spray pipe that guides the condensate pressurized by this pump to an upper spray nozzle provided at the upper part of the reactor pressure vessel, and an upper spray pipe that is directly connected to the pump. a steam turbine;
A second pipe that branches off from the pipe and guides steam to the steam turbine via a flow rate regulating valve, and a generator that is directly connected to the steam turbine and used as a control power source after rectifying the generated current. Features of nuclear reactor decay heat removal equipment.