JPS59138990A - Loss-of-coolant accident detecting logic - 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 Application of the Invention] The present invention relates to a method for detecting a loss of coolant accident in a nuclear reactor, and in particular, a method for detecting a loss of coolant accident in a nuclear reactor, using dry well pressure and temperature to determine whether or not a LOCA is occurring at the time of an abnormality in a nuclear reactor. It makes a judgment and issues an alarm signal if it is not OCA, and a scram signal if it is LOCA.

[Prior art]

The first method for detecting loss of coolant accidents in conventional boiling water reactors
As shown in the figure.

Assuming a loss of coolant accident in a boiling water reactor, the water level in multiple reactors will drop due to the coolant released from the fracture.
Drywell pressure and temperature rise.

In such an event, a known example detects a loss of coolant accident due to low reactor water level or high dry well pressure, and causes reactor scram, reactor isolation, and standby of ECC 8 to be disabled.

In the known example, a scram signal is issued by the OR circuit of low reactor water level and high dry well pressure, so dry well pressure increases other than coolant loss accidents, such as malfunction of N2 injection system, non-condensable gas from air operation, etc. Reactor scram and reactor isolation +' caused by increased dry well pressure due to leakage, etc.
ECC5 standby is performed.

As a result, there is a high possibility that pool water will be injected into the core by ECC8, and the operators will also enter into emergency operation in the event of a loss of coolant accident, resulting in a simple N.

They are forced to perform careless operations until it is determined that the injection system has malfunctioned.

Furthermore, there is a risk that unnecessary operations may cause simple reactor shutdown cooling to proceed in the wrong direction.

[Purpose of the invention]

The purpose of the present invention is to easily determine whether the cause of high dry well pressure is due to a leak of non-condensable gas (N,) or a coolant loss accident, and to avoid unnecessary scram signals. The object of the present invention is to provide a method for detecting a loss of coolant accident that avoids injection of pool water into the reactor core due to ECC8 operation and does not cause unnecessary confusion to operators.

[Summary of the invention]

The present invention generates a scram signal by using an AND circuit with the high dry well pressure and high dry well temperature at the time of a loss of coolant accident, thereby avoiding a reactor scram due to high dry well pressure other than a loss of coolant accident, and causing no inconvenience to the operator. It was designed to avoid unnecessary confusion.

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

In this embodiment, a pressure sensor for detecting a coolant loss accident and a temperature sensor for detecting a coolant loss accident combined with an AND circuit are installed in the dry well.

In the event of a loss of coolant accident, the high-temperature, high-pressure reactor-subsystem blows down into the dry well, resulting in a rise in pressure and temperature within the dry well, and the loss of coolant accident is detected based on the high pressure and temperature. (It is detected by a drop in the reactor water level.) If the dry well pressure is high other than a loss of coolant accident, there is no rise in the dry well temperature or a drop in the yX sub-reactor water level, so a loss of coolant accident is not detected and the dry well pressure A high alarm signal is issued.

It is easy to judge whether the cause of high dry well pressure is due to non-condensable gas (Nt leakage, etc.) or a loss of coolant accident, resulting in unnecessary scram signals and ECC8.
Injection of pool water into the reactor core due to activation and inadvertent disruption to the 7J Bellator can be avoided.

〔Effect of the invention〕

With the present invention, it is possible to easily determine whether the cause of high dry well pressure is due to leakage of non-condensable gas (N,) or due to a coolant loss accident, and eliminate unnecessary scram signals. Boule water injection into the core by ECC8 activation,
This has the effect of avoiding unnecessary confusion for operators.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the conventional coolant loss accident detection method due to low reactor water level and high dry well pressure, and Fig. 2 is an explanatory diagram of the conventional coolant loss accident detection method due to low reactor water level and high dry well pressure. FIG. 3 is an explanatory diagram of a method for detecting a coolant loss accident by combining high temperatures with an AND circuit. -55(

Claims (1)

[Claims] 1. In the OCA (loss of coolant accident) signal detection logic of the reactor power generation equipment, the high pressure signal and the high temperature signal are combined with an AND circuit, and the high pressure signal and LO during LOCA are combined.
Coolant loss accident detection logic that is characterized by being able to distinguish high pressure signals other than CA.