JPS6071997A - Filter for treating radioactive waste liquor - 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 [Technical Field of the Invention] The present invention relates to a filtration device for treating radiation↑1 waste fluid generated in a nuclear power plant.

[Technical background of the invention and its problems] Conventionally, a precision filtration device using a filter aid has been used as a filtration device for radioactive waste liquid generated in nuclear power plants. Due to its use, a large amount of resin waste was generated, which led to an increase in radioactive waste.

Recently, ultrafiltration (hereinafter referred to as tJF) and a filtration method using a flat membrane with a pore size of 1 μm have been adopted as a method that does not generate such secondary waste and provides better treated water quality. However, UF requires a large circulating flow rate, resulting in a complicated system configuration and high equipment costs.Furthermore, flat membrane filtration devices with a 1μ pore diameter have large pore clogging and require a large space. There is a problem.

In other words, insoluble impurities (crud) in radioactive waste liquid
When examining the particle size distribution of , it becomes as shown in Figure 1. As is clear from Fig. 1, the particle size distribution varies to some extent depending on the waste liquid, but it is mainly centered around 1 μm and almost 0.1 μm/υ
It doesn't exist.

Therefore, U F with a pore size significantly smaller than 0.1 μm
UF has the advantage that almost no solids enter the pores, and the trapped solids can be removed by backwashing, so the pores are extremely unlikely to become clogged, but UF has a small pore diameter, so the amount of water that permeates is small. Therefore, the required filtration area becomes large, and a high circulating flow rate and high filtration pressure are required.

Therefore, the device becomes complicated, and the equipment cost and space required increase.

On the other hand, in a flat membrane filtration device with a pore diameter of about 111 m, the waste liquid contains a large amount of solids with a diameter of 1 μm or less, resulting in frequent clogging and an increase in the frequency of membrane replacement.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to provide a filtration device for treating radioactive waste liquid that has a large filtration area and requires less space. be.

[Summary of the Invention] The present invention relates to a filtration device for treating radioactive waste liquid, in which a hollow fiber is installed in a container equipped with a radioactive waste liquid inlet, a filtrate outlet, a backwash water outlet, and a vent pipe. It is characterized by the provision of a filter.

[Embodiments of the invention] Embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic diagram showing an embodiment of the filtration device of the present invention.

As shown in FIG. 2, the container 1 has a radioactive waste liquid inlet 3 which introduces the radioactive waste liquid to be treated. Ill liquid outlet 5, backwash water outlet 6. Pens 1 to tubes 7 are installed, and a plurality of modules 2 of hollow fiber membranes 4 are suspended.

The radioactive waste liquid flows in from the waste liquid inflow [13, is filtered through the hollow fiber membrane 4, passes through the hollow fiber membrane, and is discharged from the filtrate outlet 5. When the filtration process progresses to a certain extent, the solid content captured in the hollow fiber membrane accumulates, so the waste liquid inflows 1]3 and i11'
A differential pressure is generated between the outlet 5 and the outlet 5.

When the differential pressure reaches a certain value, backwashing is performed and the washing waste liquid is discharged from the backwash water outlet 6. Vent pipe 7 installed in the body
is for water handling and air removal. The hollow fiber membrane is made of porous resin such as polyethylene.

In this example, hollow fiber membranes with a pore diameter of 0.1 μm and a pore diameter of 1 flIIl were used, and the relationship between the number of backwashing cycles and the change in differential pressure was investigated for each. Its conclusion is shown in Figures 3 and 4.

FIG. 3 is a graph showing the change in differential pressure when a hollow fiber membrane with a pore diameter of 1 μm is used, and FIG. 4 is a graph showing the change in differential pressure when a hollow fiber membrane with a pore diameter of 0.1 μm is used. From these graphs, it can be seen that when the pore diameter is 1 μm, the differential pressure after backwashing increases sharply, but when the pore diameter is 0.1 μm, the increase is small. This means that clogging is likely to occur with a pore diameter of 1 μm, but
At 0.1 μm, there is less clogging, indicating that when a hollow fiber membrane with a pore size of 0.1 μm is used, radioactive waste liquid filtration treatment can be performed more effectively.

[Effects of the Invention] As described above, according to the present invention, by using a hollow fiber membrane, the filtration area can be increased in a small space, and radioactive waste liquid can be effectively filtered. . In addition, if a hollow fiber membrane with an appropriate pore size is selected, clogging can be reduced, and the need for membrane replacement can be reduced.5- This also simplifies the system configuration.

[Brief explanation of the drawing]

Fig. 1 is a graph showing the distribution of clad particles in radioactive waste liquid, and Fig. 2 shows an embodiment of the filtration device for radioactive waste liquid of the present invention. lIR schematic diagrams, Figures 3 and 4 are for pore size 1, respectively.
It is a graph showing the relationship between the number of times of backwashing and the filtration differential pressure when using μm and 0.1 μm hollow fiber membranes. 1... Container 2... Module 3... Radioactive waste liquid inlet 4... Hollow fiber membrane 5... Filtrate outlet 6... Backwash water outlet 7... Vent management agent patent attorney rules Kensuke Chika (1J or 1 person) -〇-

Claims (3)

[Claims] (1) Radioactive waste liquid inlet, i1! A filtration device for treating radioactive waste liquid, characterized in that a hollow fiber membrane is disposed within a container equipped with a liquid outlet, a backwash water outlet, and a vent pipe. (2) A filtration device for radioactive waste liquid treatment according to claim 1, comprising a plurality of hollow fiber membranes of Modicol suspended within a container. (3) The filtration device for radioactive waste liquid treatment according to claim 1, wherein the hollow fiber membrane is a porous resin with a pore diameter of about 0.1 μm.