JPS592873B2 - Exhaust equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting radioactive isotopes contained in a liquid flowing inside a pipe using a radiation detector installed outside the pipe.

Conventionally, in light water reactors, in order to detect ■131, which is one of the nuclear fission products, reactor cooling water 1 was flowed through ■131 detection piping 2, as shown in Figure 1, and radiation detector 3 was used to detect ■131. was detected.

In this method, the reactor cooling water 1 is in direct contact with the inner wall of the pipe 2, so once the reactor cooling water containing 1131 flows, 131 adheres to the inner wall of the pipe 2, and the pack ground rises. .

(2) The half-life of 131 is about 8 days, which has the disadvantage that the detection sensitivity of 1131 decreases for a while afterward.

Therefore, an object of the present invention is to provide a radioisotope detection device in a liquid that overcomes the above-mentioned drawbacks of the prior art and has consistently high detection sensitivity.

The present invention will be explained in detail below using examples.

FIG. 2 is a block diagram when the present invention is implemented in a device for monitoring the amount of radioactive iodine in nuclear reactor cooling water.

The pipe 12 is installed vertically or almost vertically, and the lower part of the pipe 12 is opened to the air 18 in the tank 16.

A funnel-shaped orifice 15 is welded inside the pipe 12 above the radiation detector 14 .

This may be installed in flange style.

Tank 16 is filled with air 18 and reactor cooling water 19.

Reactor cooling water 19 accumulated in tank 16 is pumped out through piping 17.

Reactor cooling water sampled from the reactor cooling system 11
is squeezed by the funnel-shaped orifice 15 and can pass through without contacting the inner wall 13 of the detection pipe.

Therefore, ■ 131 does not adhere to the inner wall 13 of the detection pipe.

FIG. 3 is a configuration diagram showing another embodiment of the present invention.

In FIG. 3, the piping 22 is installed vertically or almost vertically, and the lower part of the piping 22 is connected to the air inside the tank 26.
It is open at part 8.

A funnel-shaped orifice 25 is welded inside the pipe 22 above the radiation detector 24 .

The piping 22 near the radiation detector 24 is cooled and heated by a heat exchanger 30.

Also, a branch pipe 31 is connected to the pipe 22 below the orifice 25.
is installed, and a valve 32 is installed in the branch pipe 31.

The tank 26 is filled with air 28 and reactor cooling water 29, and the water level of the reactor cooling water 29 is maintained within a certain range by pumping out the reactor cooling water 29 through the pipe 21. .

The operation of this embodiment will be explained below.

First, clean water is flowed into the pipe 22 from the branch pipe 31,
The pipe 22 is cooled by the heat exchanger 30 to form a thin layer of ice 33 on the inner wall of the pipe 22, and then the valve 32 is closed.

In this state, the reactor cooling water 21 sampled from the reactor cooling system flows through the orifice 25, and the radiation detector 24 detects 131.

At this time, even if the spray of reactor cooling water 21 adheres to the ice layer 33, the adhered 1131 can be removed by melting and washing away the ice layer 33 after the measurement is completed.

In addition, by constantly flowing clean water from the branch pipe 31 along the inner wall of the pipe 22 without forming an ice layer 33,
It is also possible to reduce the amount of 1131 adhering to the inner wall of the pipe 22 by wiping.

Also, since the boiling point of ■131 is 184.5℃,
The heat exchanger 30 can prevent the adhesion of 131 even if the pipe 22 is heated to about 200°C.

As explained above, according to the present invention, the radioactive isotope contained in the liquid does not adhere to the inner wall of the pipe of the radiation detection section, so the background can be suppressed and the liquid can have high detection sensitivity. A radioisotope detection device can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional radioisotope detection device in a liquid, and FIG. 2 is a block diagram showing an embodiment of the present invention. FIG. 3 is a configuration diagram showing another embodiment of the present invention. In FIG. 2, reference numeral 15 denotes an orifice for preventing the reactor cooling water 11 from coming into contact with the inner wall 13 of the pipe 12. 14 is a radiation detector. In FIG. 3, 25 is an orifice, 24 is a radiation detector, 30 is a heat exchanger, 31 is a branch pipe for supplying clean water, and 33 is an ice layer.

Claims (1)

[Scope of Claims] 1. In a device for detecting a radioactive isotope contained in a liquid flowing inside a pipe using a radiation detector installed outside the pipe, the pipe of the radiation detection section is arranged vertically or almost vertically. A radioactive isotope in a liquid that is installed vertically and configured to prevent the liquid from coming into contact with the inner wall of the pipe of the radiation detector by installing an orifice for narrowing the flow path in the pipe above the radiation detector. Detection device. 2. A device for detecting radioactive isotopes contained in a liquid flowing inside a pipe using a radiation detector installed outside the pipe, including a cooling means for forming an ice layer on the inner surface of the pipe, 1. A radioisotope detection device in a liquid, characterized in that the radiation detector is disposed outside the pipe at a position where an ice layer is formed.