JPS6111395B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to cooling equipment for a nuclear reactor vessel, and particularly to a cooling equipment for a nuclear reactor suitable for cooling a reactor pressure vessel during shutdown of a boiling water reactor.

When shutting down a boiling water reactor and removing the top cover of the reactor pressure vessel for maintenance inspections such as reactor fuel replacement, it is necessary to cool the reactor pressure vessel itself while cooling the reactor water. Therefore, conventionally, as shown in FIG. 1, the upper cover 2 of the reactor pressure vessel 1
Before removing the reactor pressure vessel 1, a pump 6 and a heat exchanger 7 are installed in parallel to a recirculation system 5 having a recirculation pump 4 that forcibly circulates reactor water (primary cooling water) 3 in the reactor pressure vessel 1.
The primary cooling water 3 is taken out by a pump 6 into a residual heat removal system 8 consisting of a residual heat removal system 8, cooled by a heat exchanger 7, and then sealed into the reactor pressure vessel 1 through a spray nozzle 9 of the upper cover 2, and then recirculated. In addition to injecting the primary cooling water 3 from the system 5, the reactor water and the reactor pressure vessel 1 itself were cooled. By the way, when cooling the reactor pressure vessel 1 itself,
By raising the water level of the primary cooling water 3 in the reactor pressure vessel 1 to the level of the upper cover 2, the reactor pressure vessel 1 can be efficiently cooled to the same temperature as the primary cooling water 3. However, in the case of FIG. 1, if this is done, the primary cooling water 3 will flow into the main steam pipe 10 that guides the steam generated in the reactor pressure vessel 1 to the steam turbine (not shown), and as a result, Metal corrosion products (cruds) 11 floating on the water surface of the primary cooling water 3 enter, so-called dust is generated in the safety relief valve 12 and the main steam isolation valves 13A and 13B, and the radiation dose rate of the main steam piping 10 is reduced. It will cause an increase. For this reason, the water level of the primary cooling water 3 is set to the level of the main steam pipe 10 to perform the above-mentioned cooling.

Therefore, the primary cooling water 3 of the reactor pressure vessel 1
Cooling of the parts not in contact with the reactor pressure vessel 1 will be performed by natural circulation of the internal atmosphere.
It took a long time to cool down the whole thing, which became a time constraint for moving on to other tasks. Further, when the reactor pressure vessel 1 is cooled, a large temperature difference occurs between the liquid phase portion and the gas phase portion of the reactor pressure vessel 1, and the resulting thermal strain has become a problem.

The present invention has been made in view of the above, and its purpose is to efficiently cool the reactor vessel without allowing crud in the coolant to enter the main steam piping when the reactor is shut down. Its purpose is to provide cooling equipment for nuclear reactor vessels.

A first feature of the present invention resides in that a means is provided for supplying coolant to the reactor vessel from a main steam pipe that guides steam generated within the reactor vessel to a steam turbine. The second feature is a means for extracting the coolant from the residual heat removal system installed in parallel with the forced circulation path of the reactor primary cooling water from the main steam pipe, purifying it, supplying the cooled coolant to the reactor vessel, and other features. The reactor vessel is provided with means for supplying a coolant of the system to the reactor vessel to fill it with water.

Hereinafter, the present invention applied to a boiling water reactor will be explained in the second section.
This will be explained in detail using the embodiment shown in FIGS.

FIG. 2 is a system diagram showing an embodiment of the cooling equipment of the present invention. However, the same parts as in FIG. 1 are indicated by the same reference numerals, and their explanation will be omitted. In Figure 2,
A reactor purification system 20 consisting of a piping 15 branched from the residual heat removal system 8, a circulation pump 16, a non-regenerative heat exchanger 17, a primary cooling water purification device 18, and a regenerative heat exchanger 19 is connected to the reactor water supply piping 21. A connecting pipe 23 is provided which is branched before the valve 22 at the part where it joins the main steam pipe 10, and the connecting pipe 23 is connected to the main steam pipe 10 between the main steam isolation valve 13A and the main steam isolation valve 13B outside the containment vessel 14. do. Since the communication pipe 23 is connected to the main steam pipe 10 outside the containment vessel 14, there is no need to arrange the communication pipe 23 through the containment vessel 14, and it is not necessary to newly provide a pipe penetration part in the containment vessel 14. There is no.

When the reactor is shut down and the reactor pressure vessel 1 and reactor water 3 are to be cooled for maintenance inspections such as fuel exchange, the primary cooling water 3 is injected by forced circulation using the recirculation system 5, and Primary cooling water 3 is injected from the spray nozzle 9 of the upper lid 2 through the residual heat removal system 8, and is further purified and cooled by the reactor purification system 20 through the connecting pipe 23 and the main steam pipe 10. Inject primary cooling water 3. At this time, the main steam isolation valve 13B prevents cooling water from being supplied to the turbine.
Closed. Main steam isolation valve 13A is open. In addition, in this state, desalinated water (primary cooling water) in the condensate storage tank (not shown) is supplied from the reactor water supply pipe 21 to the reactor pressure vessel 1 to fill the reactor pressure vessel 1 with water. Do it like this.

In this way, when the inside of the reactor pressure vessel 1 is filled with water, the crud 1 floating on the surface of the reactor water 3 can be removed.
1 does not flow into the main steam piping 10, and the relief safety valve 12 and the main steam isolation valves 13A and 13
There is no possibility that so-called dust traps will occur in B, and the radiation dose rate of the main steam pipe 10 will not increase. Furthermore, since the reactor pressure vessel 1 is filled with primary cooling water 3, the reactor pressure vessel 1 is cooled to a uniform temperature, and the problem of thermal strain occurring in the reactor pressure vessel 1 is eliminated. Moreover, the cooling time can be significantly shortened.

Therefore, the upper cover 2 of the reactor pressure vessel 1 can be opened quickly, and maintenance inspection can be started quickly. This will shorten the shutdown period of boiling water reactors and improve their operating rates.

FIG. 3 is a system diagram showing another embodiment of the present invention,
The same parts as in FIG. 1 are designated by the same reference numerals. Third
In the figure, desalinated water in a condensate storage tank 24 is introduced through a heater 26 by a transfer pump 25 to the main steam pipe 10 between the main steam isolation valve 13A and the main steam isolation valve 13B provided in the main steam pipe 10. It is supplied to the reactor pressure vessel 1 via the main steam isolation valve 13A and the main steam piping 10, and the reactor pressure vessel 1
I made sure to fill it with water. At this time, the main steam isolation valve 13B is closed. In this case, although not shown, the primary cooling water 3 is injected from the residual heat removal system 8 shown in FIG. 1 in addition to the recirculation system 5, and the heater 26 is This was provided in order to make the temperature of the desalinated water from the condensate storage tank 24 comparable to that of the primary cooling water 3. Even if the configuration is as shown in FIG. 3, the effect is the same as in the case of FIG.

As explained above, according to the present invention, the reactor vessel can be efficiently cooled without allowing crud in the coolant to enter the main steam piping when the reactor is shut down.

[Brief explanation of drawings]

Fig. 1 is a system diagram of a conventional reactor pressure vessel cooling equipment, Fig. 2 is a system diagram showing an embodiment of the reactor pressure vessel cooling equipment of the present invention, and Fig. 3 is a system diagram showing another embodiment of the reactor pressure vessel cooling equipment of the present invention. It is a system diagram showing an example. DESCRIPTION OF SYMBOLS 1...Reactor pressure vessel, 2...Upper lid, 3...Primary cooling water, 5...Recirculation system, 8...Residual heat removal system, 9...Spray nozzle, 10...Main steam piping, 20... ... Reactor purification system, 21 ... Reactor water supply pipe, 23 ... Connection pipe, 24 ... Condensate storage tank, 25 ... Phase shift pump, 26 ... Heater.

Claims (1)

[Scope of Claims] 1. A device for cooling a reactor vessel when a nuclear reactor is shut down, comprising means for supplying coolant to the reactor vessel from a main steam pipe that guides steam generated within the reactor vessel to a steam turbine. Cooling equipment for a nuclear reactor vessel characterized by comprising: 2. The reactor vessel cooling equipment according to claim 1, wherein the means supplies the coolant in the condensate storage tank to the reactor vessel to fill it with water. 3. In systems that cool the reactor vessel during reactor shutdown, a residual heat removal system installed in parallel with the forced circulation path of the reactor primary coolant from the main steam pipe that guides the steam generated in the reactor vessel to the steam turbine. It is characterized by comprising means for supplying the reactor vessel with coolant that has been extracted, purified and cooled, and means for supplying coolant from another system to the reactor vessel to fill it with water. cooling equipment for the reactor vessel.