JPS60113190A - Cooling system of boiling-water type 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 is directed to a boiling water reactor (hereinafter referred to as BWR), in which atomic This invention relates to a boiling water reactor cooling system that can efficiently remove heat generated in a reactor.

[Technical background of the invention and its problems] In a BWR, a core consisting of a large number of fuel assemblies is placed inside the reactor pressure vessel, primary cooling water is supplied to this core, and water is released by heat generation in the core. It is boiled to obtain steam. This steam is supplied to the turbine side, and the condensed coolant is supplied to the reactor core again. In this case, the reactor core contains cooling water and steam at high temperature and high pressure (approximately 285°C and 170 kg/c!).

That is, the primary cooling water in the conventional BWR will be explained based on FIG.

The cooling water that has flowed into the reactor pressure vessel 1 is transferred to the towncomer 2.
from the lower plenum 3 to the core 4 containing fuel assemblies.
It receives heat and becomes a two-phase flow of steam and water. This two-phase flow enters the steam dome 7 from the upper blenheim 5 via the dryer 6. Steam passes from the main steam pipe 8 to the turbine 9 to the condenser 10
It becomes water (fluid). This water is preheated by the feed water heater 11 and flows into the reactor pressure vessel 1 from the water feed pipe 12. When the turbine 9 does not require steam, the steam passes through the turbine bypass piping 13 and becomes water in the condenser 10.

A feed water heating pipe 14 is provided to secure steam for heating the feed water. Cold water is supplied to the reactor core 4 through the emergency core cooling piping 15 in order to cool the fuel rods of the reactor core 4 in the event of a loss of coolant accident. In this case, the water supplied from the emergency core cooling piping 15 is heated in the reactor core 5 to fill the reactor core 5 with water (or into a two-phase flow state), and then is drained into the reactor containment vessel.

In such a WR cooling system, if the primary piping connected to the reactor pressure vessel breaks, the fluid inside the reactor pressure vessel will flow out of the vessel.

Such an accident is called a loss of coolant accident (LOCA).

Even during LOCA, heat is generated in the fuel section of the reactor core. In order to remove this generated heat, emergency core cooling water is injected into the reactor pressure vessel during LOCA (ECC8>
have.

The temperature of the injected water rises due to heat from the core fuel section,
Some of it becomes steam and flows out of the pressure vessel. This method allows the heat generated in the core fuel section to escape to the outside of the reactor pressure vessel.

In this system, the water that cools the reactor core fuel section may contain some radioactive materials, so there is a high possibility that radioactive materials will escape outside the reactor pressure vessel in the event of a LOCA.

Therefore, there is a need for a boiling water reactor cooling system that can sufficiently cool the core fuel section during a LOCA and can minimize the amount of radioactive material released from the reactor pressure vessel.

[Object of the invention] The present invention has been made in response to such conventional circumstances,
To provide a reactor cooling system that can remove heat generated in the reactor core to the outside of the reactor pressure vessel without causing radioactive substances contained in the cooling water that cools the fuel part during LOCA to flow out of the reactor pressure vessel. be.

[Summary of the Invention] In other words, the present invention involves introducing steam generated by heating a coolant in a core in a reactor pressure vessel to a turbine through main steam piping, condensing it in a condenser, and supplying the condensed water with water. In a boiling water reactor cooling system in which a circulation line is supplied from a water supply pipe to the reactor pressure vessel through a heater, a first heat exchanger disposed on a dryer in the reactor pressure vessel; , a second heat exchanger connected to the first heat exchanger via outflow and inflow piping and connected to the discharge side water supply piping of the feed water heater; This is a boiling water reactor cooling system characterized by comprising a third heat exchanger having a branch valve branched from outflow and inflow pipes connecting the first heat exchanger.

[Embodiment of the Invention] An embodiment of the system according to the present invention will be described below with reference to FIG. Note that the same parts in FIG. 2 as in FIG. 1 are designated by the same reference numerals and are denoted by -C.

That is, in FIG. 2, cooling water that has flowed into the reactor pressure vessel 1 passes through the downcomer 2, passes through the lower brenum 3, and receives heat in the reactor core 4 containing the fuel assemblies, resulting in a two-phase flow of steam and water. This two-phase flow flows through the dryer 6 through the upper blenheim 5.
After that, enter Steam Dome 7. The steam passes through a main steam pipe 8, a turbine 9, and a condenser 10 where it becomes water (fluid). This water is preheated by the feed water heater 11 and flows into the reactor pressure vessel 1 through the water feed pipe 12. Note that when the turbine 9 does not require steam, water flows through the steam turbine bypass piping 13 to the condenser 1o.

In addition, in order to secure steam for heating the feed water, the feed water heating piping 14
is established. Furthermore, cold water is supplied to the reactor core 4 through the emergency core cooling piping 15 in order to cool the fuel rods of the reactor core 4 in the event of a loss of coolant accident. In this case, the emergency core cooling pipe 15
The supplied water is heated in the reactor core 5 to fill the reactor core 5 with water (or into a two-phase flow state), and then is discharged into the containment vessel.

In addition to the above, the cooling system of the present invention also provides a cooling system for the reactor pressure vessel 1.
a first heat exchanger 16 installed in the first heat exchanger 16;
a second heat exchanger 17 that heats the water supply with the heat obtained from the heat exchanger 16; and a third heat exchanger 18 that exhausts the heat obtained from the first heat exchanger 16 to the outside. The outflow pipe 19 exiting from the first heat exchanger 16, the inflow pipe entering the first heat exchanger 16, and the outflow pipe 19 from the first heat exchanger 16 are connected to the second heat exchanger 17 and the third heat exchanger 17. It is composed of a branch valve 21 and a valve 22 for branching to the exchanger 18.

In the event of a loss of coolant accident such as a rupture of the circulation line of the reactor-subcooling system, water for cooling the reactor core is supplied into the reactor pressure vessel 1 from the emergency core cooling piping 15). This water receives heat in the reactor core (), becomes heated water or steam, fills the core with water (or enters a two-phase fluid state), and then flows out of the rupture hole into the reactor containment vessel outside the reactor vessel. Since this outflow fluid passes directly through the core fuel section, there is a high possibility that it contains radioactive materials. In this case, water from the emergency core cooling pipe 15 is supplied to the core until the core 4 is filled with fluid.

The steam generated in the core is cooled and condensed in the first heat exchanger 16, and returns to the core to cool the fuel rods. First heat exchanger 1
The heat received in the first heat exchanger 16 is exhausted by the third heat exchanger 18 through the pipe 19 and valve 22 that exits the first heat exchanger 16.
The fluid cooled in the heat exchanger 18 is transferred to the first heat exchanger 1.
6 and returns to the first heat exchanger 16 via an inlet pipe 20 that enters the heat exchanger 16 .

As a result, the heat generated in the reactor core 4 is exhausted to the outside of the reactor pressure vessel 1 using a separate fluid from the fluid that directly cools the reactor core, and radioactive materials are prevented from flowing out of the reactor pressure vessel 1. Can be minimized.

Further, during abnormal operation of the nuclear reactor (when heating feed water), the heat generated in the reactor core is removed by the cooling system of the first heat exchanger 16 and the third heat exchanger 18.

During normal reactor operation or abnormal operation (however, when heating of feed water is required), the heat received by the first heat exchanger 16 is transferred to the first heat exchanger 1.
The feed water is heated in the second heat exchanger 17 via an outflow pipe 19 and a valve 21 coming out from the heat exchanger 6, and the cooled fluid enters the first heat exchanger 16 via an inflow pipe 20 to the first heat exchanger. Return to 16.

[Effects of the Invention] As explained above, according to the present invention, heat is taken from the reactor core through an external loop separate from the reactor pressure vessel, so that in the event of a loss of reactor coolant accident, radioactive materials flowing out from the fuel rods are It is possible to minimize leakage to the outside of the furnace pressure vessel. Also, during reactor operation, water supplied to the reactor can be heated.

[Brief explanation of the drawing]

Figure 1 is a system diagram showing a conventional nuclear reactor-subcooling system.
FIG. 2 is a system diagram showing an embodiment of the nuclear reactor cooling system according to the present invention. 1......Reactor pressure vessel 2...
・・・・・・・・・Evening Uncomer 3・・・・・・・・・
・・・Lower plenum 4・・・・・・・・・Reactor core 5・・・・・・・・・Upper plenum 6・・・・・・
・・・・・・Dry V 7・・・・・・・・・Steam Dome 8・・・・・・
・・・・・・Main steam piping 9・・・・・・・・・Turbine 10・・・・・・・・・Condenser 11・・・・・・・・・・・・...Water heater 12...
......Water supply piping 13...
・Turbine bypass piping 14・・・・・・・・・・・・
Feed water heating piping 15...Emergency core cooling piping 16...First heat exchanger 1
7... Second heat exchanger 18...
......Third heat exchanger 19...
... Outflow pipe 20 ... Inflow pipe 21.22 ... Branch valve agent Patent attorney Sa Suyama -

Claims (1)

[Claims] (1) The steam generated by heating the coolant in the reactor core inside the reactor pressure vessel is guided to the turbine through the main steam piping, then condensed in the condenser, and the condensed water is passed through the feed water heater and discharged from the feed water piping. In a boiling water reactor cooling system having a circulation line supplying to a reactor pressure vessel, a first heat exchanger disposed on a dryer in the reactor pressure vessel; connected via outflow and inflow piping,
and a second pipe connected to the discharge side water supply pipe of the feed water heater.
and a third heat exchanger having a branch valve branched from outflow and inflow pipes connecting the second heat exchanger and the first heat exchanger. boiling water reactor cooling system.