JPS58205895A - Atomic power plant - 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 The present invention relates to a nuclear power plant, and particularly to a nuclear power plant suitable for suppressing reactor output during partial load operation.

As is well known, in power generation plants, an operating method is adopted in which the output of the prime mover, that is, thermal power, and in nuclear couplants, the output of the steam turbine is changed in response to changes in the generation capacity, which is the load, in a manner that follows this change. In this case, it is not uncommon for the output of the steam turbine to drop to less than half of the rated output, and it is natural that a large amount of steam is not required to drive the steam turbine in such partial load operation. However, if the amount of steam sent to the steam turbine decreases, in the water supply system of a nuclear power plant that uses the extracted steam as heating steam, the temperature of the feed water will also drop to compensate for the decrease in heating steam. If the temperature drop in the feed water becomes larger than expected, there is a concern that the following problems will occur.In other words, the core of a boiling water reactor has a large number of fuel rods in the channel box 1, as shown in Figure 1. The fuel assembly consists of approximately 750 to 880 fuel assemblies 3 containing 2. Here, the coolant, or feed water, flows from the bottom of the core to the 30 channels of the fuel assemblies 3, where it is used for nuclear reactions. The steam bubbles f'fr are generated in response to the heat generated and escape to the L section, but when the temperature of the feed water at the inlet decreases, it takes a long time to boil while flowing through the fuel assembly 2. Therefore, vapor bubbles f
decreases, and the proportion of steam bubbles f in the entire core becomes smaller. In other words, since the proportion of water increases, the supply water, which is a coolant, also serves as a moderator, so the density of the moderator becomes higher than during rated operation, υ, and as a result, the atomic atom The furnace output changes in the direction of increasing.

However, what is required in this situation is that the steam turbine side is already operating at partial load, so the reactor output should be suppressed, and in order to further stabilize the reactor core, boiling of the feed water must be carried out at the fuel assembly 2. The purpose is to ensure that this occurs at the inlet of the system. Therefore, conventionally, in such cases, the second
As shown in the figure, if the load exceeds 35 cm, the output can be controlled by controlling the water supply flow rate of the recirculation pump attached to the reactor, and if it is lower than that, the output can be controlled by driving the control rods. was doing.

However, in the former case, the reactor core may become excessively unstable when the supply water flow is completely wiped out to suppress output, and this tendency is especially severe in plants that use recirculation pumps built into the reactor. 6'b. On the other hand, in the latter case, the control response is slow and the problem cannot be handled smoothly.

An object of the present invention is to provide a nuclear power plant in which the reactor output during partial load operation is suppressed without changing the feed water flow rate, thereby greatly contributing to the stabilization of the reactor core.

An embodiment of the present invention will be described below with reference to FIG.

In FIG. 3, reference numeral 1 denotes a nuclear reactor, and this reactor 1 has main steam, which is connected to a turbine 3 via a pipe 2.
A generator 4 serving as a load is connected to this turbine 3. Furthermore, the turbine 3 is in communication with a condenser 5 which recovers the exhaust gas and circulates it back into the system. The condenser 5 is connected to a low pressure heater 7 via a condensate pump 6, and the low pressure heater 7 and the turbine 3 are connected to each other by a first bleed pipe 8. Further, the low pressure heater 7 is connected to a high pressure heater 10 via a water supply pump 9.
0 and the turbine 3 are connected to each other by a second bleed pipe 11. Therefore, an additional heater 12 is provided in the path connecting the high pressure heater 10 and the nuclear reactor 1.
A high-temperature steam pipe 13 that supplies heating steam to the additional heater 12 is branched from the main steam pipe 2. The high-temperature steam pipe 13 is also provided with a control valve 14, and the control circuit of this control valve 14 includes a temperature detector 15 that detects the temperature of the inlet water supply to the reactor 1, and converts its output signal into an electrical signal. The control valve 14 is provided with a regulator 16 which provides a valve opening command signal to the control valve 14. Furthermore, high pressure heater 1
An additional heater 12 is installed on the path connecting 0 and reactor 1.
A bypass pipe 18 having an on-off valve 17 is provided to detour therefrom. In the figure, numerals 19 and 20 indicate a main steam stop valve and a steam control valve, and numerals 21 and 22 indicate a heater inlet valve and a heater Yamaguchi valve, respectively.

Next, the effect will be explained.

■1 During normal operation, high-temperature, high-pressure steam sent from the raw metal reactor 1, that is, main steam, passes through the main steam pipe 2 and enters the turbine 3, where it drives the generator 4 that is directly connected to the turbine shaft. and finish the work. Subsequently, the exhaust gas from the turbine 3 is collected in a condenser 5, where it exchanges heat with cooling water sent by a pump (not shown) and becomes condensed water. This condensate is extracted by a condensate bomber and sent to a low pressure heater 7, where primary heating is performed by extracted steam from the turbine 3 sent via a first bleed pipe 8. Further, the condensate is sent to the high-pressure heater 10 by the water supply pump 9, and secondary heating is performed in this high-pressure heater IO, but the condensate here is called "supply water". In the high pressure heater 10, the water supply is the second bleed pipe]
1￥i- It is further heated to a high temperature by the bleed air sent through it. Next, the feed water bypasses the heater 12 before the heater inlet valve 21 and enters the reactor 1 through the bypass pipe 18, where it is heated again and turned into steam. Repeat. Note that during this time, the control valve 14 is fully closed, and the heater 12 is closed.
There is no flow of steam to.

(2) During zero partial load operation When the normal operation shifts to partial load operation, the heater inlet valve 21 and the heater outlet valve 22 are fully opened, and the on-off valve 17 located in the path of the bypass pipe 18 is fully closed. During this time, the amount of steam sent to the turbine 3 decreases because the opening degree of the steam control valve 20 is narrowed, and the amount of steam sent from the turbine 3 to the low pressure heater 7 and the high pressure heater 10 also decreases. Although the temperature of the feed water is thus inevitably lower than during rated operation, the control valve 14 is opened to introduce a portion of the main steam to the additional heater 12 through the high-temperature steam pipe 13. That is, a part of the main steam sent from the reactor 1 is sent to the high temperature steam pipe 13 to the additional heater 12 whose internal pressure is set lower than the inlet of the turbine 30.
It flows all the way through and gives heat to the water supply that passes through it. As a result, the temperature of the p-feed water is increased to promote boiling within the reactor core, and the reactor power is suppressed. During this period, the feed water flow rate is not particularly changed, and only the feed water temperature is controlled by the temperature detector 15 and the regulator 16 by adjusting the main steam extraction flow -3tfr&.

As described above, the present invention has the excellent effect that the feed water temperature does not decrease even during partial load operation of the plant, and the destabilization of the reactor core caused by this can be avoided. .

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the flow of feed water in the reactor core, Fig. 2 is a diagram showing the relationship between output and flow rate control in a nuclear power plant, and Fig. 3 is an example of a nuclear power plant according to the present invention. Fig. 1 is a systematic diagram ′ shown in FIG. l...Reactor 2...Main steam pipe 3...Turbine 5...Condenser 7...Low pressure heater
9... Water supply pump 10... High pressure heater 1
2...Additional controller 13...High temperature steam pipe 14...Control valve 15...Temperature detector 16.
...Regulator 17...Opening/closing valve 18...Bypass pipe (7317) Attorney Kei Chika (1 person) Figure 1 Figure 2 0 36% /θθχ Supply 2 to Ori 1

Claims (1)

[Claims] An additional heater is provided in the path connecting the high-pressure heater and the reactor, and has a bypass pipe that bypasses this during normal operation and leads the feed water directly from the high-pressure heater to the reactor. A high-temperature steam pipe that guides the supplied steam as a heating medium, and a control valve that is located in the path of this high-temperature steam pipe and that adjusts the flow rate of the steam introduced into the additional heater by increasing the valve opening degree. A nuclear power plant equipped with