JPH0317598A - Removal system for residual heat of nuclear reacter - Google Patents

Abstract

PURPOSE:To decrease operators' load and to enable keeping an integrity of both a pressure suppression room and a containment vessel by actuating automatically a nuclear reactor water injection mode by a signal of a containment vessel pressure high or a nuclear reactor water level low. CONSTITUTION:Although a nuclear water injection is automatically actuated by a signal of a pressure suppression room pressure high D or a pressure suppression room temperature high E, a water injection mode A is predominantly actuated when a demand signal for a nuclear reactor water injection mode A is indicated. Moreover, to not-allow-when-an-subsignal-exists F, a signal of a containment vessel pressure high B or a nuclear reactor water level low C is fed as a subsignal. Then, in case of the pressure high B or the water level low C, the water injection mode A functions. However, in case that the pressure high D or the temperature high E occurs by whatever reasons, a pressure suppression room cooling down mode G is automatically actuated and the pressure suppression room can be quickly cooled down. In this way, for a cooling down of a reactor core, whole conventional functions are reserved and for a cooling down of a pressure suppression pool, an automatic cooling down can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention (Industrial Application Field) The present invention relates to a nuclear reactor residual heat removal system for removing decay heat and sensible heat from a reactor core when the reactor is shut down.

(Prior Art) A nuclear reactor residual heat removal system is a system for removing radioactive decay heat of fission products generated by nuclear fission during operation from the reactor core after the operation of the nuclear reactor is stopped.

Conventional reactor residual heat removal systems serve both reactor water injection mode and containment vessel cooling mode. As shown in FIG. 3, reactor water injection mode A is automatically activated by a signal C indicating high containment vessel pressure B or low reactor water level. Containment vessel cooling mode is activated manually, and operators must confirm that the reactor water level has recovered before switching to containment vessel cooling mode, which places a burden on operators. The containment vessel cooling mode is divided into two: containment vessel spray and pressure suppression chamber cooling. Regarding containment vessel spray, there is a risk of water droplets splashing onto the equipment and electrical components inside the containment vessel, so careful judgment must be made when operating it manually.

Cooling of the pressure suppression chamber is easy to automate because there are no devices in the pressure suppression chamber that would be exposed to cooling water. As a reactor residual heat removal system that actually operates the pressure suppression chamber spray in response to a pressure suppression chamber pressure high signal, for example, a reactor containment vessel spray device disclosed in Japanese Utility Model Application Publication No. 56-48095 is known.

A conventional nuclear reactor residual heat removal system will be explained with reference to FIGS. 4 to 7. Figure 4 shows a system diagram of the reactor residual heat removal system.

In FIG. 4, a nuclear reactor 1 is housed in a containment vessel 2, and a pressure suppression chamber 3 is provided in the lower part of the containment vessel 2. In the pressure suppression chamber 3, the tip of a vent pipe 4 is opened in pool water. is immersed in it. A containment vessel spray sparger 5 is provided in the containment vessel 2, and a pressure suppression chamber spray sparger 6 is provided in the pressure suppression chamber 3. One end of a containment spray line 9 having a pump 7 and a heat exchanger 8 is connected to the lower part of the pressure suppression chamber 3, and the other end of the containment spray line 9 is connected to a containment spray sparger 5. .

Further, one end of the reactor water injection line is connected to the reactor water injection line branched from the containment vessel spray line 9, and this reactor water injection line 10
The other end is connected to the reactor 1.

One end of a pressure suppression chamber spray line 11 is connected to the pressure suppression chamber spray sparger 6 , and the other end of the pressure suppression chamber spray line 1 l is connected to a containment vessel spray line 9 .

Further, a pressure suppression chamber return line 12 is connected between the inside of the pressure suppression chamber 3 and the containment vessel spray line 9. In addition, the symbol I3 in the figure is a vacuum breaker valve. 14 is a relief safety valve,
15 is the containment vessel pressure gauge. +6 is the pressure suppression chamber pressure gauge,
17 indicates a pressure suppression chamber thermometer.

Therefore, in the event of a reactor loss of coolant accident, reactor water injection mode A, which is activated by a signal of high containment vessel pressure B or low reactor water level C shown in FIG. 3, will cause the system shown in bold lines in FIG. The residual heat removal system operates accordingly. After the water level in the reactor has been restored, the operator can manually switch to the containment vessel spray mode using the route shown in bold line in Figure 6 at the operator's discretion.

If reactor steam directly flows into the suppression chamber space and high pressure or temperature occurs in the suppression chamber other than during a reactor loss of coolant accident, as shown in Figure 7, It has been proposed to automatically start in the suppression chamber cooling mode by a signal from the pressure gauge 16 or the thermometer 17.

(Problem to be solved by the invention) However, since the reactor residual heat removal system has both a reactor (core) water injection function and a containment vessel cooling function, when core cooling is required, priority is given to the core water injection function. need to be activated. Therefore, it is necessary to use the two functions described above to operate effectively. The cited publication mentioned above focuses only on the latter, and does not disclose that priority is given to the water injection function of the reactor core.

Conventional nuclear reactor residual heat removal systems have the problem of increased workload on operators as described in 1 above, as well as problems with the integrity of the pressure suppression chamber and containment vessel.

The present invention has been made in view of the above points, and aims to automate the functions of the reactor residual heat removal system to the maximum extent possible, automatically start the pressure suppression chamber cooling among the containment vessel cooling, and give priority to the core cooling. An object of the present invention is to provide a nuclear reactor residual heat removal system that can reduce the load on operators and maintain the integrity of a pressure suppression chamber and a containment vessel.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a nuclear reactor that combines the core water injection function of a boiling water reactor and the containment vessel cooling function of a reactor containment vessel having a reactor pressure suppression chamber. In the residual heat removal system, when a high pressure signal or a high temperature signal in the pressure suppression chamber occurs, the pressure suppression chamber automatically starts in cooling mode, and when a low water level signal in the reactor water occurs, the pressure suppression chamber automatically starts up in cooling mode. The present invention is characterized in that the water injection mode is automatically started with priority, or the cooling mode of the pressure suppression chamber is automatically started in response to a high pressure signal of the reactor containment vessel.

(Function) The reactor residual heat removal system of the present invention automatically operates in reactor water injection mode in response to a signal indicating high containment vessel pressure or low reactor water level. In addition, it automatically operates in the suppression chamber cooling mode depending on the pressure in the suppression chamber or the temperature in the pressure suppression chamber. However, if both mode request signals are issued at the same time, priority is given to core cooling. That is, it operates as a reactor water injection mode. Furthermore, if the pressure or temperature rises in the pressure suppression chamber for some reason, the pressure suppression chamber cooling mode can be automatically activated to cool the pressure suppression chamber.

(Embodiment) A first embodiment of the nuclear reactor residual heat removal system according to the present invention will be described with reference to the startup circuit diagram of FIG. In addition,
In this example, explanation of the same parts as the conventional example is omitted,
I will only explain the main points.

Further, the reactor containment vessel and the piping system around the reactor are also similar to those shown in FIG. 4, so their description will be omitted.

In Fig. 1, it is automatically activated by a signal of pressure suppression chamber pressure high D or pressure suppression chamber temperature high E, but if a request signal for reactor water injection mode A is issued, reactor water injection mode A is activated with priority. .

In the figure, F indicates disallowance when an auxiliary signal is present, and G indicates the suppression chamber cooling mode, and F indicates disallowance when an auxiliary signal is present. Input as a signal.

Therefore, in this embodiment, when the containment vessel pressure is high B or the reactor water level is low C, the reactor water injection mode A functions as in the conventional case. However, if a high pressure D or a high temperature E in the pressure suppression chamber occurs for some reason, the pressure suppression chamber cooling mode G is automatically activated, and the pressure suppression chamber can be quickly cooled.

In this way, the same function as before for core cooling is ensured, and the pressure suppression pool can be cooled automatically, reducing the burden on operators and maintaining the integrity of the reactor and containment vessel. I can do it. FIG. 2 shows a second embodiment of the present invention, and the same parts as in FIG.

In FIG. 2, the pressure suppression chamber cooling mode G is automatically activated in response to a high containment vessel pressure B signal, and the reactor water injection mode A is automatically activated in response to a low reactor water level C signal. If both modes G and A are required at the same time, reactor water injection mode A takes priority. In this embodiment, starting in reactor water injection mode A in the event of a loss of coolant accident is the same as in the conventional case. Furthermore, if the pressure in the pressure suppression chamber were to rise, the pressure would open the vacuum breaker valve 13 shown in Figure 7 and flow into the containment vessel, so it is expected that a signal indicating high pressure B in the containment vessel would be issued immediately. . As a result, the pressure suppression chamber cooling mode G is automatically activated, and the health of the pressure suppression chamber can be maintained.

[Effects of the Invention] According to the present invention, in the event of a loss of coolant accident in a nuclear reactor, the reactor water injection mode can be operated in the same manner as in the past, and the integrity of the nuclear reactor can be maintained.

Further, in the case of an event in which the pressure in the pressure suppression chamber increases, the pressure suppression chamber cooling mode is activated, and the health of the pressure suppression chamber can be maintained.

Therefore, together with these factors, the load on the operators can be reduced and the health of the reactor, the suppression chamber, and the containment vessel can be maintained.

[Brief explanation of the drawing]

1 and 2 are start-up circuit diagrams respectively showing the first and second embodiments of the nuclear reactor residual heat removal system according to the present invention,
Figure 3 is a startup circuit diagram showing a conventional nuclear reactor residual heat removal system.
Figures 4 to 7 are diagrams for explaining the conventional nuclear reactor residual heat removal system, in which Figure 4 is a basic configuration diagram, Figure 5 is a diagram showing the operation in reactor water injection mode, FIG. 6 is a system diagram showing the operation in the containment vessel spray mode, and FIG. 7 is a system diagram showing the operation in the pressure suppression chamber cooling mode. ■ Reactor 2 Containment vessel 3 Suppression chamber 4 Vent pipe 5 Containment vessel spray sparger 6 Suppression chamber spray sparger 7 Pump 8・Heat exchanger 9... Containment vessel spray line 0... Reactor water injection line 1... Pressure suppression chamber spray line 2... Pressure suppression chamber return line 3... Vacuum breaker valve 4... Relief Safety valve 5...Containment vessel pressure gauge 6...Pressure suppression chamber pressure gauge 7...Pressure suppression chamber thermometer (8733) Agent: Yoshiaki Inomata, patent attorney (and others)
1 person) Figure 3 Figure 4

Claims (1)

[Claims] In a reactor residual heat removal system that has both a core water injection function of a boiling water reactor and a containment vessel cooling function of a reactor containment vessel having a reactor pressure suppression chamber, a high pressure signal or a high temperature signal of the pressure suppression chamber. If this occurs, the pressure suppression chamber automatically starts in cooling mode, and if a low reactor water level signal occurs, it automatically starts with priority given to water injection mode to the reactor core, or A nuclear reactor residual heat removal system, characterized in that the system is configured to automatically start the cooling mode of the pressure suppression chamber in response to a high pressure signal.