JPS58162895A - Strainer cleaning device of emergency core cooling device - 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 strainer cleaning device for an emergency core cooling system in a boiling water nuclear reactor, which enables automation of cleaning function tests.

BACKGROUND ART Conventionally, as a water injection device for an emergency core cooling system of a boiling water reactor, there is one shown in FIG. 1, for example. That is, in the event of a loss of coolant accident in the reactor 1, the pressure suppression chamber pool water 4 stored in the pressure suppression chamber 3 in the reactor containment vessel 2 is supplied to the reactor. Pool water 4 is
After foreign matter contained in the water is removed by a strainer 5, the pressure is increased by an injection pump 7 through a pump suction valve 6, and then the water is injected into the nuclear reactor via an injection pipe 8.

By the way, this water injection device requires periodic functional tests to confirm the soundness of the water injection function. For example, it is common to perform this every few months.

In this function test, the pool water in the pressure suppression chamber 3 is transferred to the strainer 5, using the test pipe 9 which also branches from the injection pipe 8.
This is carried out by circulating a circulation path consisting of a pump suction valve 6, an injection pump 7, and a test valve 10.

However, in the conventional method, foreign matter may be mixed into the pool water, and the strainer 5 may become clogged over time during a functional test, resulting in an increase in pressure loss in the strainer portion. When this pressure loss exceeds the allowable value, the effective net suction head of the injection pump 7 exceeds the required net suction head, cavitation occurs in the injection pump, and the necessary pump flow rate for the water injection device cannot be secured. Therefore, in order to eliminate this inconvenience, it is necessary to clean the strainer when the pressure loss reaches an allowable value, but since this strainer is installed in the pressure suppression chamber 3,
Pool water must be drained from this pressure suppression chamber 3.

However, since the pool water in the pressure suppression chamber 3 contains radioactive substances, problems arise, such as the need to provide a storage tank exclusively for draining this water, and the need to dispose of fluid radioactive waste.

Note that FIG. 2 shows an example of the relationship between the strainer clogging rate and pressure loss in the pressure suppression chamber. As the clogging rate increases, the pressure loss increases as shown by curve CI. For example, since a clogging rate of 50% exceeds the allowable pressure loss value C2, it is understood that the strainer needs to be cleaned before this Ct is exceeded.

The present invention has been made based on the above circumstances, and allows cleaning of the strainer without the need to drain the pool water from the pressure suppression chamber.
Therefore, it is an object of the present invention to provide a strainer cleaning device for an emergency core cooling system that can automatically perform a functional test without the need to supply cleaning water from the outside.

This object has been achieved by the present invention, in which the discharge tip of a function test pipe for functionally testing a water injection pipe is connected to a strainer of a different water injection device so that the flow can flow back, and the strainer can be automatically cleaned by the internal backflow through this circulation path. be done.

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

Note that the same reference numerals are used for parts common to those in FIG.

One test pipe 9 is connected to the suction side of an injection pump 17 installed in a different injection pipe 18.

That is, it is connected to the upstream side of the pump suction valve 16 on the outside of the pressure suppression chamber 3 . When performing a function test of each water injection device, the test valve 10 of the own system device is opened, the pump suction valve 16 of the other system device is closed, and the injection pump 7
It is for driving.

That is, the test circulation path in this case is constituted by the strainer 5 in the pressure suppression chamber, the pump suction valve 6, the injection pump 7, the test pipe 9, the test valve 101, a different strainer 15, and the pressure suppression chamber 3.

Note that 19.20 indicates different test pipes and test valves, respectively. If the circulation path is configured like this, the flow in the strainer 15 will be in the opposite direction to the normal flow, so foreign matter attached to the strainer 15 will be removed. It is removed by this flow in the opposite direction.

Therefore, since the cleaning test of the strainer 15 can be automatically performed by the function test of the water injection device, it goes without saying that clogging of the strainer 15 over time can be prevented by the function test carried out every few months, for example. Since the cleaning action of the strainer 15 is performed only by circulating the pool water in the pressure suppression chamber 3, there is no need to specially supply cleaning water from the outside. Therefore, there is no fear that the water level of the pool water in the pressure suppression chamber 3 will rise even during cleaning.

Note that if the test piping is configured so that it does not penetrate the reactor containment vessel, it is possible to reduce the number of parts that penetrate the reactor containment vessel.

As described above, according to the present invention, during a functional test of the water injection device of the emergency core cooling system, the pressure suppression chamber strainer can be cleaned automatically and there is no need to supply cleaning water from the outside.
This makes it possible to eliminate the need for a dedicated water storage tank for draining water, as well as eliminate troublesome work such as processing of fluid radioactive waste, thereby achieving the intended purpose.

[Brief explanation of drawings]

FIG. 1 is a piping configuration diagram showing a conventional example, FIG. 2 is a characteristic diagram showing a clogging situation, and FIG. 3 is a piping configuration diagram showing an embodiment of the present invention.

Claims (1)

[Claims] 1. In an emergency core cooling system for a boiling water reactor in which pool water from a pressure suppression chamber is supplied to the reactor from an injection pipe through a strainer, water is injected into different discharge tips of the functional test pipes for functionally testing the water injection pipe. A strainer cleaning device for an emergency core cooling system, characterized in that the strainer is connected to a strainer of the device so as to cause backflow, and the strainer can be automatically cleaned by internal backflow caused by the circulation path.