JPH0321078B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to a nuclear reactor coolant leak monitoring device, and in particular, to a system for remotely detecting reactor coolant leaks and preventing accidents from occurring. The present invention relates to a reactor coolant leak monitoring device for monitoring.

[Prior art]

FIG. 1 shows a schematic configuration of a conventional pressurized water reactor as an example of a reactor coolant system. In the figure,
A reactor coolant pump 3 is connected to a steam generator 2 connected to a reactor vessel 1, and a pressurizer 4 is connected to a circuit of the reactor vessel 1. The reactor vessel 1 is loaded with fuel, and the heat generated by nuclear fission is removed by reactor coolant circulating in the reactor core.
This reactor coolant is forcibly circulated through the coolant loop by the reactor coolant pump 3, heated in the reactor, and then flows through the coolant loop piping to the steam generator 2 where it is Heat exchange is performed with system feed water A. The secondary system feed water here becomes steam B and is supplied to a turbine generator (not shown) to generate electricity.

In pressurized water reactors, light water is used as a reactor coolant, and also serves as a neutron moderator to continue the nuclear fission reaction in the reactor core. Further, the reactor coolant is pressurized to a constant pressure by a pressurizer 4 to prevent it from boiling due to heat absorption in the reactor core.

If reactor coolant leaks occur in the reactor coolant system of a nuclear power plant as described above, the reactor coolant itself is radioactive in the reactor core, so it is a direct cause of radioactive contamination to the environment. In addition, if a large amount leaks, the cooling of the reactor core may become insufficient, which could lead to serious accidents such as melting of fuel or explosion due to increased pressure. For this reason, it is desirable to detect reactor coolant leaks at a very small stage and take countermeasures at an early stage.

In order to detect such leakage of reactor coolant, conventionally, a large number of radiation dose rate meters, temperature detectors, and pressure detectors were installed in the space near the piping to detect leakage of reactor coolant. There were devices to detect increases in the air dose rate of radiation and rises in temperature and pressure, as well as devices to monitor the water level and radiation dose rate of drain tanks installed to collect leaked reactor coolant.

However, in detecting reactor coolant leaks using the conventional devices described above, it is necessary to install a very large number of detectors in order to obtain sufficient leakage detection ability, and methods for measuring the air dose rate Other methods do not directly detect leaks, so early detection is difficult, and methods that measure air dose rates do not detect leaks because gamma rays are highly penetrating and emit a lot of gamma rays during reactor operation. Even without it, the dose rate was high, resulting in problems such as difficulty in detecting minute leaks.

[Summary of the invention]

This invention was made in order to eliminate the drawbacks of the conventional ones as described above. A β-ray detector is attached to the tip of a multi-articulated arm, and this is mounted on a remote moving device to control reactor coolant piping. The object of the present invention is to provide a reactor coolant leak monitoring device that can detect reactor coolant leaks early by patrolling and monitoring the system.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. In the figure, a remote moving device 10 includes a multi-jointed arm 1 that can take a free posture in three-dimensional space.
1. A surveillance television camera 13 is supported, and a β-ray detector 12 is attached to the tip of the multi-joint arm 11. The remote mobile device 10 is connected to a control panel 15 in the central control room 6 via a communication cable 14. The control panel 15 has a surveillance television camera 1.
A monitor television 16 for displaying images No. 3 is arranged. 5 indicates the reactor coolant piping that is to be monitored.

Next, the operation will be explained. An operator in the central control room 6 operates the control panel 15 to control the remote movement device 1.
0 along an inspection route including the reactor coolant piping 5. Then stop at the point to be inspected,
Monitor TV 1 for video from surveillance TV camera 13
6, operate the multi-jointed arm to scan the β-ray detector 12 around the target equipment and piping,
Check for reactor coolant leaks. The health of the reactor coolant system can be confirmed by sequentially performing such operations on equipment and piping that require inspection.

The reason why the β-ray detector 12 is used to detect leakage of the reactor coolant is as follows. Reactor coolant is activated in the reactor core and emitted alpha rays,
It begins to emit beta rays, gamma rays, and neutron rays,
Of these, neutrons are extremely rare; α-rays have a short range of several centimeters in the air, making remote measurement difficult; and gamma-rays, which are the most conspicuously detected radiation, have limited ability to penetrate materials. Because it is strong and easily passes through walls such as piping, the air dose rate around the reactor coolant system is quite high, and even if there is a leak, the difference will not be noticeable. It has been determined that beta rays, which have a distance of several tens of centimeters or more and are completely blocked by metal piping, are most suitable for detecting leaks.

As a β-ray detector, for example, a scintillation counter using an organic material such as plastic that absorbs only a small amount of gamma rays is commercially available, and these can be used.

The arm mechanism of a general industrial robot can be used as the multi-jointed arm 11 for scanning the β-ray detector at the inspection location, but as mentioned above, β-rays have a small ability to penetrate materials, and are difficult to detect in the shadows of objects. This means that it cannot be detected at all, and that nuclear plant equipment
Piping is complicated and it is necessary to pass through the space well, so an arm with a large degree of freedom is required.

Although detailed explanation of the remote mobile device 10 will be omitted,
It may be a vehicle that runs on wheels, a vehicle that travels using a mechanism similar to a human foot, or a vehicle that travels on rails laid along the inspection route, and the vehicle may be selected as appropriate depending on the conditions of use.

Furthermore, although the communication method between the remote mobile device 10 and the control panel 15 is wired via the communication cable 14 in this embodiment, it is not limited to this.
Needless to say, it may be a wireless type using radio waves or light.

Note that there is a television camera 13 mounted on the remote mobile device 10 and a monitor television 16 that monitors the image.
is for monitoring when the operator operates the multi-joint arm 11, but can also be used to confirm the position of the remote moving device 10 at the same time. However, if the inspection procedure is determined in advance and there is no need for monitoring, it may be omitted.

In the above embodiment, the leakage detection of the coolant of a pressurized water reactor was explained as an example, but the present invention is not particularly limited to this.
It goes without saying that any type of nuclear reactor that emits radiation can be applied. In addition, although the explanation has been made on the assumption that a human operates remotely, the route to be patrolled by the remote moving device 10 and the route to be scanned by the multi-joint arm 11 are determined in advance,
A similar effect can be obtained even if the vehicle is automatically operated to monitor leakage of the reactor coolant. Furthermore, if various sensors such as a temperature sensor, humidity sensor, pressure sensor, and microphone are installed in addition to the β-ray detector, and those signals are also monitored, it is possible to monitor only the leakage of reactor coolant. This enables comprehensive operation monitoring.

〔Effect of the invention〕

As described above, according to the present invention, a β-ray detector is attached to the tip of a multi-jointed arm and mounted on a remote mobile device, so leakage of reactor coolant can be detected without installing multiple detectors. Not only can leaks be detected early and reliably, but the location of leaks can also be accurately determined.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional nuclear reactor coolant system to be monitored by the present invention, and FIG. 2 is a perspective diagram of a schematic configuration of an embodiment of the present invention. 1...Reactor vessel, 2...Steam generator, 3...
Reactor coolant pump, 4... Pressurizer, 5... Reactor coolant piping, 6... Central control room, 10... Remote movement device, 11... Multi-joint arm, 12... Beta ray detector, 13... Surveillance TV camera, 15...
Control panel, 16...Monitor TV.

Claims (1)

[Scope of Claims] 1. A remote moving device that is controlled by a control signal and travels an inspection route of a reactor coolant system, a multi-jointed arm supported by the remote moving device and controlled by the control signal, and a multi-jointed arm that is supported by the remote moving device and controlled by the control signal. β is attached to the tip of the articulated arm and measures the dose rate of β-rays in space.
A reactor coolant leak monitoring device equipped with a radiation detector. 2. The reactor coolant leakage monitoring device according to claim 1, comprising a television camera provided on a remote moving device for confirming the position of the tip of the multi-jointed arm.