JPH0517515B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides nuclear power generation equipment that prevents a sudden increase in reactor pressure that occurs when the circulation pump is stopped and the reactor is scrammed when the main steam isolation valve is closed. Regarding.

[Technical Background of the Invention] In nuclear power generation equipment using a boiling water reactor, steam generated within a reactor pressure vessel is supplied to a turbine via a main steam pipe. Coolant within the reactor pressure vessel is also circulated through the reactor core by circulation pumps, such as a plurality of internal pumps. In addition, a main steam isolation valve is installed at the part where the above-mentioned main steam pipe penetrates the reactor containment vessel, and in the event of an emergency, these main steam isolation valves are closed to isolate the inside of the reactor containment vessel. It is configured. Of course, in such a case, all control rods are fully inserted into the reactor core, the reactor is scrammed, and the safety relief valve is opened to drain excess steam generated in the reactor pressure vessel into the suppression pool. The reactor pressure vessel is configured to release the reactor to prevent pressure build-up within the reactor pressure vessel.

However, since safety is the top priority in nuclear power generation facilities, backup safety equipment is provided in case the scram caused by the control rod insertion fails. As part of this backup safety equipment, in the event of a scram failure, all internal pumps are stopped, the proportion of steam bubbles in the reactor core, or void ratio, is increased, and the amount of this coolant, which also serves as a moderator, in the core is reduced. There are things that can safely shut down a nuclear reactor.

[Problems with Background Art] By the way, when all the internal pumps are stopped as described above, the void ratio in the reactor core increases rapidly. As a result, the reactor pressure within the reactor pressure vessel rapidly increases transiently. Of course, in such a case, the safety relief valve is configured to open and release the steam generated within the reactor pressure vessel into the suppression chamber, thereby suppressing the pressure rise within the reactor pressure vessel. However, because the capacity of this relief safety valve is limited, the pressure inside the reactor pressure vessel rises excessively during a transient period. For this reason, there is a possibility that the integrity of the reactor pressure vessel and fuel will be adversely affected, and such a transient pressure increase is not desirable.

[Purpose of the invention]

The present invention has been made based on the above circumstances, and its purpose is to reduce the transient pressure of the reactor inside the reactor pressure vessel when the circulation pump such as the internal pump is stopped and the reactor is scrammed. The objective is to provide nuclear power generation equipment that can prevent a sudden increase in nuclear power generation.

[Summary of the invention]

That is, the present invention provides a reactor pressure vessel, a reactor core housed in the reactor pressure vessel, a plurality of circulation pumps that circulate coolant in the reactor pressure vessel through the reactor core, and An element that sequentially stops the plurality of circulation pumps one or more at a time when the reactor pressure rises above a predetermined pressure when the main steam isolation valve is closed in response to a reactor pressure signal in the vessel. It is equipped with a furnace pressure control device. Therefore, by stopping multiple circulation pumps in stages one by one, the sudden generation of voids in the reactor core is prevented, and the transient pressure rise in the reactor pressure vessel is prevented. It is.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. In the figure, 1 is a reactor pressure vessel, and a reactor core 2 is accommodated within this reactor pressure vessel. Furthermore, a plurality of circulation pumps, such as a plurality of internal pumps 4, are provided at the bottom of the reactor pressure vessel. The coolant 3 in the reactor pressure vessel 1 is circulated through the reactor core 2 by these internal pumps 4 . The operation of these internal pumps 4 is controlled to control the flow rate of the coolant 3 passing through the reactor core 2, that is, the core flow rate, and by controlling the core flow rate, the core flow rate is controlled.
The reactor is configured to control the void fraction within the reactor and control the output of the reactor. In addition, if all these internal pumps 4... are stopped, the reactor pressure vessel 1
As described above, the coolant 3 inside the reactor undergoes natural circulation, the core flow rate decreases, the void ratio within the reactor core 2 increases, and the reactor is shut down.
Further, control rods 15 are inserted into or withdrawn from below into the reactor core 2 by control rod drive mechanisms 20 to shut down the reactor, adjust reactivity, etc.

The steam generated in the core 2 is separated from water by a steam separator 23, moisture is removed by a steam dryer, and then sent to the turbine 8 via the main steam pipe 5. Drive 8. Note that a main steam isolation valve 6 and a main steam control valve 7 are provided in the middle of the main steam pipe 5. and,
The steam discharged from the turbine 8 is transferred to a condenser 10
It is condensed and becomes condensate. Then, this condensate is returned into the reactor pressure vessel 1 via the condensate pump 12, the water supply pipe 11, and the water supply pump 14. The feedwater pump 14 is configured to be driven by a feedwater pump driving turbine 13, and the feedwater pump driving turbine 13 is driven by main steam extracted from the main steam pipe 5. In addition, relief safety valves 16 are connected to the main steam pipe 5, and when the reactor pressure rises above a predetermined pressure, these relief safety valves 16 open.
The reactor pressure vessel 1 is configured to release steam into a suppression chamber (not shown) so that the reactor pressure within the reactor pressure vessel does not rise above a predetermined pressure.

Such nuclear power generation equipment is provided with a reactor pressure control device 17. Further, a reactor pressure detector 22 for detecting the reactor pressure inside the reactor pressure vessel 1 is provided. The reactor pressure signal 18 detected by the reactor pressure detector 22 is sent to the reactor pressure control device 17. This reactor pressure control device 17 is used to control the internal pressure when the main steam isolation valve 6 is closed and the reactor is isolated, and when the scram due to control rod insertion fails and the reactor pressure rises excessively. It is configured to send a trip signal to the pumps 4 to stop these internal pumps 4. When the reactor pressure control device 17 stops the internal pumps 4, for example, it first stops 3 of the 12 internal pumps 4, and then, after a 3 to 5 second delay, three more. It is configured to stop the internal pumps 4... in this way, and in this way, the internal pumps 4...
... are configured to stop one or more of them in a step-by-step manner.

Next, the operation of this embodiment will be explained. When an abnormality occurs in the reactor, the main steam isolation valve is closed, the reactor is isolated, and all the control rods 15 are fully inserted into the reactor core 2, causing the reactor to be scrammed. However, if the scram caused by the insertion of the control rods 15 fails, steam continues to be generated from the reactor core 2.
In such a case, the relief safety valves 16 are opened and the generated steam is released into the suppression chamber, but under high power conditions, the generated steam cannot be released completely, and the atoms in the reactor pressure vessel 1 are Furnace pressure increases. In this case, the increase in the reactor pressure is detected by the reactor pressure detector 22, and the reactor pressure signal 18 is sent to the reactor pressure control device 17. Then, the reactor pressure control device 17 sends a trip signal 19 to the internal pumps 4 where the reactor pressure exceeds a predetermined pressure, and sequentially stops these internal pumps 4, for example, three at a time. let Therefore, the core flow rate decreases little by little, and the void ratio within the core 2 does not increase rapidly. Therefore, when the reactor is shut down in this manner, the reactor pressure does not rise suddenly and transiently.

Incidentally, FIG. 2 shows the characteristics of this embodiment when the nuclear reactor is shut down. That is, as is clear from FIG. 2, when the number of internal pumps that are stopped increases sequentially, the reactor pressure decreases and then increases only slightly, and there is no transient pressure increase.

〔Effect of the invention〕

As described above, the present invention includes a reactor pressure vessel, a reactor core housed in the reactor pressure vessel, a plurality of circulation pumps that circulate coolant in the reactor pressure vessel through the core, and a reactor core housed in the reactor pressure vessel. If the reactor pressure rises above a predetermined pressure when the main steam isolation valve receives the reactor pressure signal in the reactor pressure vessel and closes, the above-mentioned plurality of circulation pumps are sequentially activated one or more at a time. It is equipped with a reactor pressure control device to shut down the reactor. Therefore, by stopping several circulation pumps one by one in stages, it is possible to prevent the sudden generation of voids in the reactor core and to prevent a transient pressure rise in the reactor pressure vessel. The effects are great, such as being able to do the following.

[Brief explanation of the drawing]

The figures show one embodiment of the present invention, with FIG. 1 being a schematic configuration diagram and FIG. 2 being a diagram showing the characteristics of reactor pressure fluctuations when the reactor is shut down. 1...Reactor pressure vessel, 2...Reactor core, 4...Internal pump (circulation pump), 6...Main steam isolation valve, 8...Turbine, 17...Reactor pressure control device, 22...Atom Furnace pressure detector.

Claims (1)

[Claims] 1. A reactor pressure vessel, a reactor core housed in the reactor pressure vessel, a plurality of circulation pumps that circulate coolant in the reactor pressure vessel through the core, and atoms in the reactor pressure vessel. A reactor pressure control device that receives a reactor pressure signal and sequentially stops the plurality of circulation pumps one or more at a time when the reactor pressure rises above a predetermined pressure when the main steam isolation valve is closed. Nuclear power generation equipment characterized by comprising: