JPS58146896A - Particles and elements trapping apparatus - 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 radiation control facilities, and particularly to particles of samples with high radioactivity levels, particles suitable for collecting iodine, and an iodine collection device.

Regarding the release of gases containing radioactive substances, such as radioactive rare gases, radioactive iodine, and particulate radioactive substances, IIJ is constantly monitoring. Of these, particulate radioactive substances are collected by a filter, and radioactive iodine is adsorbed onto an adsorbent and collected separately, after which its radiation level is measured. Conventional particle and iodine trapping devices target gases with relatively low radioactivity levels, so they cannot be used in situations such as a loss of coolant accident at a nuclear power plant, which involves the release of highly concentrated radioactive materials. In the event of an accident, there is a drawback that during operations such as removing the filter, the user will be exposed to radiation from the radioactive substances present in the pipes within the collection device. Radiation exposure can be reduced by shielding pipes, but the radiation level expected in the event of an accident is 10 times higher than normal levels.
”～10＠ times as much, and a large amount of shielding material (lead: 101～
To obtain an attenuation rate of 10@, the r-ray energy must be α5MeV.
The disadvantage is that it requires about 11 to 13 crn).

The purpose of the present invention is to reduce the exposure dose during operation by extruding and replacing radioactive substances other than those attached to the collection filter in the collection device with clean gas (e.g. nitrogen) after collection. Provides a particle and iodine collection device (there is one).

The present invention combines a three-way valve, a two-way valve, and piping, and opens and closes them in an appropriate order to replace radioactive materials remaining in the piping inside the collection device with clean gas after extraction and collection. It is something.

The present invention will be explained below based on the drawings. ・Figure 1 shows a conventional embodiment, in which the sample gas entering from the sample inlet pipe 1 is heated by a heating device 2 to increase the collection efficiency of the collection material O. Particulate radioactive substances and radioactive iodine are collected in the collector 4. The sample gas is sucked in by the pump 7, and the flow meter 5
, the flow rate control device 6 controls the flow rate to be constant. After collecting for a certain period of time, remove the collection material from the collector 4, collect it, and analyze the radioactivity. If the radioactivity level is low as during normal operation, the However, in the case of an accident in which a large amount of radioactive material is released, such as a loss of coolant accident, the exposure dose during operation is not a problem even if sample gas is present in the sample gas. ~1
The radioactivity level is 6 times higher, and the exposure dose becomes a non-negligible amount.The present invention aims to reduce this exposure dose. Fig. 2 is a system diagram showing an embodiment of the present invention.

As shown in Figure 2, a combination of three-way valves and two-way valves are opened and closed in an appropriate order. The exposure dose based on sampling during a loss-of-coolant accident can be reduced by replacing the air with easily available air (such as nitrogen, which is generally supplied from readily available nitrogen gas cylinders). Figures 3 to 6 show the operating status of sampling after a loss of coolant accident occurs.
Among the symbols indicating valves in Figures 3 to 6, the direction in which the triangle mark is filled in indicates the closed state, and the direction in which it is not filled in indicates the open state. Shows the purging state, and the temple gas is from the three-way valve IG, 1.
1, the sample gas flows from the piping 16 to the flow meter 5, and the inside of the piping from the sampling point to the collection device is replaced with the sample gas.Next, FIG. is three-way valve 10,11°12.13
t, and flows to collection No. 6, where particulate radioactive substances and radioactive iodine are collected. At this time, since the radioactivity level is high, most of the sample gas bypasses the collector 4 and flows from the three-way valve 10 to the two-way valve 14 and the pipe 16★. Cleaning condition inside collector 4 and some piping
t, the clean gas pushes out the O sample gas in the collector 4 through the three-way valve 12 and the three-way valve 13, and is replaced.

The clean gas entering from the two-way valve 10 flows into the pipe 16 via the three-way valve 11, and cleans and replaces the inside of the pipe along its route. Figure 6 shows the cleaning status of the nine piping parts left after cleaning in Figure 5.
It shows that the clean gas enters from the three-way valve 10 and the three-way valve 13, flows through the pipe 16, and, together with the 5th WJgD cleaning, cleans and replaces all the sample gas after the three-way valve 10. According to the present invention, all the sample gas in the piping inside the collection device can be cleaned and replaced with clean gas, reducing the exposure dose during operation. There is an effect that can be done.

[Brief explanation of drawings]

Fig. 1 is a system diagram of a conventional zero-particle, iodine collection device, and Fig. 2 is a system diagram of a particle, iodine collection device according to the present invention.
6IIg from FIG. 3 is an operating state diagram of FIG. 20. 4... Collector %5... Flow meter, 6... Flow rate control device, 7... Pump, 10.11, 12.13... Three-way valve, 14.15... Two-way valve. 81 Country map 2

Claims (1)

[Claims] 1. A particle and iodine collection device comprising a sample pump, a flow rate control device, a heater, and a filter holder, characterized in that the device is equipped with a three-way valve and a two-way valve.