JPH04122892A - boiling water 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 [Field of Industrial Application] The present invention relates to a boiling water nuclear reactor in which water is forcedly circulated within the reactor core by a water supply system.

[Conventional technology]

In boiling water reactors that do not have conventional recirculation systems or internal pumps, there is a method of forced circulation using a water supply system to increase core output.

A boiling water reactor, which uses a conventional water supply system to forcefully circulate the core, has a water supply system as described in "Study of Natural Circulation BWR with Feedwater Driven Jet Pump" at the 1989 Autumn Conference of the Atomic Energy Society of Japan. The water is branched into two systems, one for supplying water to the core water sparger and the other for jet pumps, and the water supply ratio is adjusted by flow rate adjustment valves in each prefecture.

[Problem to be solved by the invention]

The above conventional technology cannot increase the output of the reactor because the amount of flow into the reactor core is limited in natural circulation reactors that do not have forced core circulation equipment such as recirculation systems or internal pumps. A method of increasing the core output by branching the water supply system into a conventional natural circulation reactor and using part of it as a forced core circulation system to increase the amount of inflow into the core has been considered. A method of increasing the core output by increasing the core flow rate by installing a jet pump that uses this feed water as driving water between the walls of the pressure vessel has been considered; When a pump is installed in a pressure vessel, a jet pump creates flow resistance, so with conventional feed water pumps, the effect of using a jet pump is canceled out, making it difficult to increase reactor output. there were. In addition, in conventional boiling water reactors with forced core circulation systems or internal pumps, the circulation pumps are located inside the reactor containment vessel, making it difficult to inspect and maintain the equipment.

The present invention provides a boiling water reactor with a jet pump that uses feed water as the driving water, by increasing the pressure of the jet pump hydraulic water and increasing the amount of water flowing into the reactor core, thereby achieving high core output and a highly reliable plant. The purpose is to provide a boiling water reactor that can be obtained.

[Means to solve the problem]

In order to achieve the above object, the boiling water reactor of the present invention has a booster pump installed outside the reactor containment vessel in the water supply line connected to the jet pump that uses the supply water as active water, and a booster pump is installed outside the reactor containment vessel. This is achieved by increasing the flow rate into the reactor core by increasing the dynamic pressure, and by locating water supply line pumps, valves, feed water heaters, etc. outside the reactor containment vessel.

[For production]

The boiling water reactor described above has a forced core circulation system in which the water supply piping of a boiling water reactor without a recirculation system or internal pump is branched into two water supply branch pipes, one of which is connected to a downcomer below the reactor water level. One end is connected to the upper space inside the reactor, and the other is connected to a water supply drive jet pump installed inside the downcomer, and a pump is installed on the water supply piping to pressurize the supply water so that it can be injected into the reactor pressure vessel. The temperature of the feed water is adjusted by a feed water heater, and flow rate adjustment valves are installed in the water supply branch pipes to adjust the flow rate to each water supply branch pipe so that the feed water can be injected into the reactor pressure vessel. The water supply branch pipe connected to the drive jet pump is pressurized by a booster pump and the temperature of the water supply is adjusted by a water heater.

In this way, low-temperature water is supplied to the water supply branch pipe connected to the top of the downcomer, and high-temperature water is supplied to the water supply branch pipe connected to the water supply active jet pump. Low-temperature water with a high degree of subcooling can flow in and condense steam bubbles mixed in the downcomer, and the water supply branch pipe connected to the water supply active jet pump is pressurized by the booster pump, increasing the water supply active pressure. As the amount of water in the downcomer increases, a large amount of water in the downcomer can be supplied into the core, and as a result, the core output increases as the amount of water flowing into the core increases.

In addition, by installing a ring header in the downcomer between the reactor pressure vessel wall and the shroud wall, and by placing the location within the downcomer where the water supply branch pipe branches to multiple jet pumps, the water supply branch that penetrates the reactor pressure vessel The number of tubes can be minimized.

Furthermore, the flow rate of the water supply branch pipe connected to the jet pump can be adjusted using the flow rate adjustment valve installed in the water supply branch pipe, so in order to increase the core output, the opening degree of the flow rate adjustment valve must be increased and the core output must be suppressed. By reducing the opening degree of the flow control valve, it becomes possible to control the reactor core output without operating the barrier rods.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 7.

FIG. 1 is a longitudinal sectional view showing an embodiment of a boiling water nuclear reactor according to the present invention. In FIG. 1, steam generated in a reactor pressure vessel 1 in a boiling water reactor that uses a water supply system as an in-core forced circulation system passes through a dryer 5 and then enters a turbine 7 through a main steam pipe 6. After driving the turbine 7, the steam that enters the condenser 8 via the condensate pump 21 is cooled and returned to water, and this water passes through the water supply pipe 9 and then through the water supply branch pipes 11 and 12. Reactor pressure vessel 1
Return to Here, the water supply branch pipe 11.12, the booster pump 17, the flow rate regulating valve 13.14, and the feed water heater 15 are installed outside the reactor containment vessel 18.

The water supply pipe 9 led to the downcomer 4 between the reactor pressure vessel 1 and the shroud 3 surrounding the reactor core 2 branches into a water supply branch pipe 11 and a water supply branch pipe 12 on the way, and the water supply branch pipe 11 is connected to the top of the downcomer 4. At the same time, the water supply branch pipe 12 is connected to the lower part of the downcomer 4. The water supply pipe 9 is pressurized and temperature-controlled by a required number of water supply pumps 10 and water supply heaters 19. Further, each of the water supply branch pipe 11 and the water supply branch pipe 12 has a flow rate adjustment valve 13 and a flow rate adjustment valve 1.
4 is installed, and the ratio of water flowing from the water supply pipe 9 to the water supply branch pipe 11 and the water supply branch pipe 12 can be adjusted. In addition, a booster pump 17 and a feed water heater 1 are connected to the water supply branch pipe 12 connected to the water supply drive jet pump 16 at the bottom of the downcomer 4.
5 is installed, and is configured to increase the pressure of water supplied to the water supply drive jet pump 16 and adjust the temperature.

FIG. 2 is a sectional view taken along the line AA in FIG. 1, showing a first embodiment of the boiling water nuclear reactor according to the present invention. In FIG. 2, the water supply branch pipe 12 in FIG.
5 and a booster pump 17 are installed outside the reactor containment vessel 18 to adjust the pressure, temperature, and flow rate within this water supply branch pipe 12. Here, the water supply branch pipe 12 further branches into five pipes at a position outside the reactor pressure vessel 1 within the reactor containment vessel 18 as shown in FIG. 4 and a water supply drive jet pump provided at the lower part] 6.

In the above configuration, the water supply branch pipe 11 connected to the upper part of the downcomer 4
is set to low-temperature water supply, and the water supply branch pipe 12 connected to the water supply drive jet pump 12 at the bottom of downcomer 4 is set to high-temperature water supply. As a result, when the low-temperature water supply from the water supply branch pipe 11 is sufficiently supplied to the amount of steam bubbles mixed into the downcomer 4, the steam bubbles are completely condensed, and the hydrostatic head of the downcomer 4 and the core 2 flow rate are ensured. In this way, by changing the water supply flow rate ratio between the water supply branch pipe 11 and the water supply branch pipe 12 within the flow rate range that allows complete condensation of steam bubbles, the reactor core 2
Core power can be controlled by adjusting the subcooling degree of artificial cooling water.

FIG. 3 is a characteristic diagram illustrating the relationship between the booster pump 17 pressure and the core 2 flow rate ratio in FIGS. 1 and 2. In the operation of this boiling water reactor, the pressure inside the reactor pressure vessel 1 is approximately 70 kg during plant operation. Further, the discharge pressure within the reactor pressure vessel 1 of the reactor water supply system in which the feed water driven jet pump 16 is driven by the water supply is higher than the pressure within the reactor pressure vessel 1 during plant operation. If this pressure is A kg/ci, the booster pump 17 of the water supply branch pipe 12 connected to the water supply dynamic jet pump 16 has a maximum pressure of about 20 kg/cd as shown in FIG. The maximum discharge pressure to the water supply drive jet pump 16 is approximately A+20 kg/cIi. Here, the characteristics of the discharge pressure (IIi dynamic pressure) of the water supply branch pipe 12 to the feed water drive jet pump 16 and the core 2 flow rate ratio shown in FIG. When the core flow rate ratio when is Akg/ad is "'standard value 1", a high core flow rate ratio can be obtained by using the booster pump 17 with a discharge pressure range of 10 to 20 kg/cd.

According to this embodiment, the booster pump 17 is installed in the water supply branch pipe 12 connected to the water supply driven jet pump 16 at the bottom of the downcomer 4, and the booster pump 17 is set at a higher driving pressure than the conventional water supply driven jet pump. As a result, the amount of water supplied from the downcomer 4 by the water supply dynamic jet pump 16 can be increased, so the amount of water flowing into the core 2 can be increased, and furthermore, this increase in the amount of water flowing into the core can increase the core output. can be increased. In addition, the booster pump 17 and feed water heater 15 installed in the water supply branch pipe 12 are installed outside the reactor containment vessel 18.
This makes it easier to inspect equipment during plant operation, which has the effect of improving plant reliability.

FIG. 4 is a sectional view taken along the line AA in FIG. 1, showing a second embodiment of the boiling water nuclear reactor according to the present invention. In FIG. 4, the water supply branch pipe I2 in FIG.
5 and a booster pump 17 are arranged outside the reactor containment vessel 18 to adjust the pressure, temperature, and flow rate within this water supply branch pipe 12. Here, the feed water branch pipe 12 is guided into the reactor pressure vessel 1 at the rear of the feed water heater 15 without being branched to each feed water drive jet pump 16 as shown in FIG. The water supply pipe 12 led to the reactor pressure vessel 1 and the shroud 3 is connected to a ring header 20 provided at the bottom of the downcomer 4, and this ring header 20 is connected to the five water supply drive jet pumps 1.
6 and distributes water sent from the water supply branch pipe 12 to each water supply drive jet pump 16.

According to this embodiment, in addition to the effects of the first embodiment, the hole penetrating the reactor pressure vessel 1 can be minimized when connecting the water supply branch pipe 12 and the water supply drive jet pump 16. In addition, the exposure dose can be reduced by reducing the number of water supply branch pipes 12 outside the reactor pressure vessel 1, making it easier to arrange the water supply branch pipes 12 inside the reactor containment vessel 18, which makes the plant safer. This has the effect of improving economic efficiency by supplying

FIG. 5 is a longitudinal cross-sectional perspective view of the main parts of FIGS. 1 and 4, showing a third embodiment of the boiling water nuclear reactor according to the present invention. In FIG. 5, the water supply branch pipe 12 in FIGS. 1 and 4 includes a flow rate regulating valve 14, a feed water heater 15, and a booster pump 17.
is arranged outside the reactor containment vessel 18, and adjusts the pressure, temperature, and flow rate within this water supply branch pipe 12. Here, the water supply branch pipe 12 is connected to a water supply heater 15 as shown in FIGS. 4 and 5.
The reactor pressure volume W! is not branched to each feed water drive jet pump 16 at the rear of the reactor pressure volume W! A water supply branch pipe 12 led into the reactor pressure vessel 1 is connected to a ring header 20 provided at the bottom of the downcomer 4 between the reactor pressure vessel 1 and the shroud 3. The ring header 20 is connected to five water supply drive jet pumps 16 and distributes the water sent from the water supply branch pipe 12 to each water supply drive jet pump 16, but here, as shown in FIG. A nozzle 22 for supplying water to the water supply driving jet pump 16 is provided at the lower part of the jet pump 20 .

In the above configuration, the longitudinal cross-sectional shape of the ring header 20 shown in FIG. 5 is an elliptical shape or a streamlined shape with the long axis in the vertical direction.

This makes it possible to minimize the rate of decrease in the flow path area of the water flowing downward in the downcomer 4 between the reactor pressure vessel 1 and the shroud 3 by the rudder 20 to the ring. The flow path resistance caused by the ring header 20 for water flowing through the ring header 20 can be minimized.

According to this embodiment, in addition to the effects of the second embodiment, it is possible to minimize the flow resistance of water due to the ring header 20 within the downcomer 4, thereby improving plant efficiency.

FIG. 6 shows a fourth embodiment of the boiling water reactor according to the present invention, and shows the relationship between the core 2 flow rate and the core 2 power ratio in FIGS. 1 and 2 or 4 or 4 and 5. It is a characteristic side view of a relationship. FIG. 7 is a characteristic diagram illustrating the plant operating method of FIG. 6. In this boiling water reactor, the water supply pipe 9 shown in FIG. is installed. Further, a booster pump 17 is connected to the water supply branch pipe 12 connected to the water supply drive jet pump 16, and the water supply drive jet pump 1 is connected to the booster pump 17.
This is a configuration that can increase the driving pressure of 6.

In the operation of this boiling water reactor, on the one hand, the water supply branch pipe 12
The amount of water supplied can be adjusted by adjusting the opening degree of the flow rate adjustment valve 14 provided in the. Figure 6 illustrates the relationship between the core 2 flow rate and the core 2 power ratio when the control rod position is constant, and the area between B and 0 of the core exit ratio in Figure 6 is the natural circulation region of the core flow rate. However, the area between A and B of the core power ratio is an operating region where the core flow rate is controlled depending on the amount of water supplied to the feed water instant jet pump 16, and based on this characteristic, the amount of water supplied to the feed water driven jet pump 16 is 2 outputs to area A-B
can be controlled within the range of

According to this embodiment, by controlling the amount of water supplied to the water supply immediate-acting jet pump 16 without operating the control rods, the plant can be controlled within the region A-B of the core power ratio as shown in FIG. This method allows the plant to be operated more safely in accordance with the demand for electricity, and has the effect of improving the economic efficiency of the plant.

〔Effect of the invention〕

According to the present invention, it is possible to control the core power by changing the degree of subcooling of the cooling water at the core inlet, and furthermore, by increasing the amount of inflow into the core and increasing the core power, there is an effect of improving the economic efficiency of the plant. .

Furthermore, the reduction in the number of water supply branch pipes outside the reactor pressure vessel has the effect of improving plant safety and economic efficiency.

Furthermore, the economical efficiency of the plant can be improved by reducing the water flow path resistance of the ring header in the downcomer.

In addition, it is possible to suppress the reactor core power of the plant more safely, and the economic efficiency of the plant can be improved by controlling the reactor core power. Installing it outside the containment vessel has the effect of making equipment inspection and adjustment easier.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing one embodiment of the boiling water reactor according to the present invention, and FIG.
FIG. 3 is a characteristic diagram illustrating the relationship between booster pump pressure and core flow rate ratio in FIGS. 1 and 2, and FIG. 4 is a cross-sectional view taken along line A-A in FIG. A, -A sectional view of FIG. 1 showing the second embodiment of the boiling water reactor,
FIG. 5 is a vertical cross-sectional perspective view of the main parts of FIGS. 1 and 4 showing a third embodiment of the boiling water reactor according to the present invention, and FIG. 6 is a fourth embodiment of the boiling water reactor according to the present invention. The first example of
FIG. 7 is a characteristic diagram illustrating the method of operating the plant shown in FIG. 6. 1...Reactor pressure vessel, 2...Reactor core, 3...Shroud, 4...Downcomer, butt...Dryer, 6...Main steam pipe, 7...Turbine, 8...Condensate Vessel, 9...
Water supply piping, 10... Water supply pump, 11.12... Water supply branch pipe, 13.14... Flow rate adjustment valve, 15.19...
Feed water heater, 16... Water feed water jet pump, 17
... Booster pump, 18 ... Reactor containment vessel, 20
...Ring header, 21...Condensate pump, 22...
·nozzle. Agent Patent Attorney Tadashi Akimoto Actual Diagram] 6 Figure Diagram 7° jj, [Thff1 force (kg/
crrr? ) Figure A-A Page 1 Figure Figure ■ Turn B-1-Kaoru

Claims (1)

[Claims] 1. A reactor core made of nuclear fuel, a shroud surrounding the reactor core,
In a boiling water reactor consisting of a pressure vessel containing a shroud, the water supply system that supplies coolant to the reactor is branched into multiple lines, and one of the lines is pressurized using a booster pump to connect the shroud wall and the pressure vessel. A boiling water nuclear reactor characterized in that water is used to drive a jet pump provided in a downcomer between walls, and other systems are connected to the liquid phase part of the downcomer. 2. To supply water to a jet pump driven by the water supplied by one series of water supply pipes branched into the plurality of water supply pipes in the downcomer between the shroud wall of the pressure vessel and the pressure vessel wall. 2. The boiling water nuclear reactor according to claim 1, further comprising a ring header, and a branch nozzle for supplying driving water from the ring header pipe to a plurality of jet pumps in the downcomer. 3. By making the cross-sectional shape of the ring header pipe provided inside the downcomer longer in the vertical direction of the downcomer and shorter in the lateral direction, the flow path area of the water flowing inside the downcomer is increased and the flow path resistance due to the ring header is reduced. The boiling water nuclear reactor according to claim 2, characterized in that it has a shape that can be made small. 4. Claim 1, characterized in that a plurality of water supply pipes branched into the plurality of systems are provided with valves, and the flow rate of the drive water flowing to the jet pump can be adjusted by the opening degree of the valves.
Or the boiling water nuclear reactor according to claim 2 or 3.