JPS5936532A - Multistage iodine filter of sgts - Google Patents

Abstract

PURPOSE:To reduce the dose to be exposed to the operator in the stage of exchanging charcoal filters for iodine in a gas treatment system for emergency purpose by dividing said filters to plural pieces to decrease the capacity for capturing iodine in the fore stages. CONSTITUTION:Charcoal filters for iodine in a fore gas treatment system 5 in a gas treatment system for emergency purpose are divided to 13-15, and the filters 13, 14 are made into the panel type which has a smaller capacity for capturing iodine and is easily attachable and detachable. If the gas treatment system for emergency purpose operates in the event of a trouble in a nuclear reactor, the greater part of radioactive iodine is absorbed in the filter 13 of the 1st stage and even if the amt. of the released iodine is large and exceeds the capacity of the filter in the 1st stage, the iodine is adsorbed by the filter 13 in the next stage. The amt. of the radioactive iodine in each one stage of the filters is small and the filters are of the easily attachable and detachable panel type; therefore, the dose to be exposed to the operator in the stage of exchanging the filters is reduced and since the operator is just required to exchange the filter 13 or 14, this method is economical.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a monthly charcoal filter such as an emergency gas treatment system, and particularly to a multi-stage iodine removal filter suitable for reducing the radiation exposure of an operator when replacing the filter.

A conventional emergency gas treatment system is comprised of a filter system 11 and a ventilation fan 2, as shown in FIG. In the unlikely event that an accident occurs in the reactor, the regular ventilation system 3 is isolated and the emergency gas treatment system is activated.

As a result, the reactor building 4 is under negative pressure to prevent radioactive substances from leaking from the building and to remove radioactive iodine by the filter system l.

As shown in FIG. 2, the filter system 1 is composed of a pre-gas treatment device 5 and a post-gas treatment device 6. Inside it, there are charcoal filters 11, 12. High performance particle filter 10. In addition, there is also a moisture removal device 7 and a heating coil 8 to prevent the efficiency of these filters from decreasing due to moisture, and a blur filter 9 to prevent the efficiency of the high-performance particle filter IO from decreasing due to clogging. is the provision.

Now, assuming an accident, most of the radioactive iodine will be stored in the charcoal filter 1 in the pre-gas treatment device 5.
1, and the dose can be large.

An object of the present invention is to provide a multi-stage iodine removal filter that reduces radiation exposure to an operator when replacing a monthly charcoal filter such as in an emergency gas treatment system.

It is known that radioactive iodine collected in a charcoal filter decreases exponentially from the upstream side of the filter with respect to the thickness of the filter.

Further, the efficiency of the filter tends to deteriorate near the surface of the filter. Therefore, by dividing the conventional filter into a plurality of filters and reducing the prestage total iodine collection capacity, the amount of element collection per filter stage can be reduced. Furthermore, the design uses a nominal type design that is easy to handle, reducing filter replacement time and reducing radiation exposure for operators.

An embodiment of the present invention will be described below with reference to FIG. Third
In the filter system of the emergency gas treatment system shown in the figure, the regular charcoal filter in the pre-gas treatment system 5 is divided into filters 13, 14, and 15. Furthermore, the filters 13 and 14 have a small iodine scavenging capacity and are easy to install and remove.As a result, if the emergency gas treatment system is activated during an accident,
Most of the radioactive iodine is first adsorbed by the first stage filter 13. In the unlikely event that the volume of the discharged waste is large and exceeds the capacity of the first stage filter, the waste will be adsorbed by the next stage filter 14.

Therefore, according to this embodiment, (1) the amount of radioactive iodine collected per filter stage is small, and the filter is of a panel type that is easy to attach and detach, which has the effect of reducing the radiation exposure of the operator when replacing the filter.

■ To prevent deterioration of filter performance during normal times and accidents.
Because you only need to replace filter 13 or 14,
Economical.

- Under normal conditions, the filter 13 can be replaced regularly to prevent deterioration of filter efficiency due to moisture.

According to the present invention, the regular charcoal filter is divided into a plurality of pieces like an emergency gas treatment system, and the volume t of the front stage is reduced.
Since it is a panel type that is easy to install and remove, it is possible to reduce the radiation exposure of the operator when replacing the filter.

[Brief explanation of the drawing]

Figure 1 is a system diagram showing the emergency gas treatment system, and Figure 2 is a system diagram showing the emergency gas treatment system.
FIG. 3 is a block diagram showing a conventional filter system, and FIG. 3 is a block diagram showing an embodiment of the present invention. 1... Filter system, 2... Ventilation fan, 3... Regular ventilation system, 4... Reactor building, 5... Front gas treatment device, 6... Post gas treatment device, 7...Moisture removal device, 8...Heating coil%9...Prefilter, 10
...High performance particle filter, 11.12...Charcoal filter for regular use, 13,14.15...Multi-stage charcoal filter for wood l Go to Kaihin h1

Claims (1)

[Claims] 1. In the emergency gas treatment system consisting of a filter system and a ventilation fan, a multi-stage charcoal filter is divided into multiple parts to reduce the required capacity for iodine collection in the front stage. 5GTS multi-stage filter for regular use.