JPH0259700A - Radioactive waste liquid treatng system - Google Patents

Abstract

PURPOSE:To efficiently eliminate a radioactive nuclear species by scavenging a suspended matter in a waste liquid by a hollow fiber filter and scavenging an ionic radioactive nuclear species by using a scavenger. CONSTITUTION:A waste liquid which is collected to a collecting tank T1 is transferred to a hollow fiber filter F1 by a pump P1, and the greater part of a suspended solid is eliminated. Subsequently, radioactive concentration of treated water is measured by a detector D1, and when the concentration is low enough, the treated water is transferred to a treated water tank T3. When the concentration is high, the treated water is transferred to a reaction tank T2, and an ionic radioactive nuclear species is scavenged by throwing in a scavenger such as an inorganic ion exchanger, etc., from a scavenger tank T4, and thereafter, said water is fed to a hollow fiber filter F2 by a pump P2 and the scavenger is eliminated and transferred to the treated water tank T3. Next, radioactive concentration of outlet water of the hollow fiber filter F2 is measured by a detector D2, and unless it is reduced enough, the water is returned to the reaction tank T2 and the processing is executed again.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention relates to a radioactive waste liquid treatment system for treating radioactive waste liquid generated in a radionuclide handling facility.

(Prior Art) Radioactive waste liquid is generated from facilities that handle radionuclides, such as nuclear power plants, nuclear fuel reprocessing plants, and facilities that handle radioactive isotopes. The composition of these radioactive waste fluids varies greatly even in the same facility. Only representative nuclides generated within each facility are listed below.

(1) Nuclear power plant = Cr, "'Mn,"8
Co.

The majority are nuclides such as 59Fe and 60Co, and 131
137 Ruka If C9 or C9 is included, also see.

(2) Nuclear fuel reprocessing plants: The nuclides contained in the waste fluid include Cs, Cs, Sr, and many other nuclides.

(3) Facilities that handle radioactive isotopes: The facilities that handle radioactive isotopes are not decided yet, so they vary from facility to facility.

Conventional radioactive waste liquid treatment systems are explained using a nuclear power plant as an example. At this facility, treatment systems differ depending on the level of conductivity of the waste liquid. That is,
The waste liquid with low conductivity is treated in a system connected to a T-filter 1 and a desalination device 2 filled with ion exchange resin, as shown in FIG.

Here, the filter 1 is a device for removing suspended matter in waste liquid, and the desalting device 2 is a device for removing ionic components that have passed through the filter 1. On the other hand, high-conductivity waste liquid is treated in a treatment system in which an evaporative concentrator 3 and a desalination device 2 are connected as shown in FIG.

The filter 1 is the latest equipment that uses a hollow fiber membrane filter. In this way, the desalination device 2 filled with granular ion exchange resin or the like is provided after the filter 1 or the evaporator 3, and 54Mn and 60Co are removed at the same time as suspended matter is removed by the filtration device 1. A desalting device 2 removes ionic components. When processed in the evaporative concentrator 3, the concentrated liquid contains 4Mn.

6°Go remains.

(Problem to be solved by the invention) Most of the radionuclides contained in the waste liquid, including not only C9 and Sr, are extremely dilute from a chemical standpoint, even if their radioactivity concentration is high. be. Considering that low-potency ions are removed using an ion-exchange resin, high-concentration components other than the radionuclides contained in the water are removed, and the waste liquid becomes more purified and approaches pure water, but the low-potency The ionic components (radionuclides) of are usually not reduced in the same way (at the same rate).

Therefore, it is considered that ionic nuclides are detected even through the desalination device 2. Furthermore, since Cs is a monovalent cation and has a large ionic radius, it is thought that it is difficult to be captured by an ion exchange resin (it has a small affinity with ion exchange groups).

In any case, conventional treatment systems have the disadvantage that they are not effective in removing Cs, Sr, etc. among ionic radionuclides.

The present invention was made in order to solve the above-mentioned drawbacks, and the present invention was made to solve the above-mentioned drawbacks.
The purpose of the present invention is to provide a radioactive waste liquid treatment system that combines efficient separation and collection of Co, 54Mn, etc.).

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the radioactive waste liquid treatment system according to the present invention is characterized by the following items (1) to (5).

(1) A collection tank for collecting radioactive waste liquid, and a hollow fiber membrane filter at the front stage connected to this collection tank and used to separate and collect suspended matter contained in the radioactive waste liquid;
A reaction tank for receiving the treated water treated by the hollow fiber membrane filter in the previous stage for further treatment, a collection agent tank for storing a collection agent to be introduced into the reaction tank, and the reaction tank. a stirring device for mixing the treated water and the scavenger received in the reaction tank; and a hollow fiber in the latter stage for decomposing and collecting only the scavenger from the scavenger-containing solution after the reaction in the reaction tank. A membrane filter, a treated water tank that receives treated water treated by the subsequent hollow fiber membrane filter, and suspended solids discharged during backwashing of each of the hollow fiber membrane filters and used capture. It is characterized by comprising a sludge receiving tank that receives the collection agent.

(2) A first radiation detector for in-line measuring the radioactivity concentration of the treated water treated with the preceding hollow fiber membrane filter, and a signal from the first radiation detector to determine the radioactivity concentration. The present invention is characterized by comprising a control device that determines whether the concentration is high or low, and if the concentration is sufficiently low, determines not to transfer the treated water to the reaction tank but to transfer it to the treated water tank.

(3) A second radiation detector for in-line measuring the radioactivity concentration of the treated water treated with the latter hollow fiber membrane filter, and a signal from the second radiation detector that detects the radioactivity. The degree of a degree is determined, and if the concentration has not been sufficiently reduced, a decision is made to return the treated water to the reaction tank, and at the same time backwashing of the scavenger adhering to the hollow fiber membrane filter at the latter stage is performed. It is characterized by being equipped with a control device for issuing commands.

(4) If the differential pressure of the filter increases even though the capacity as a scavenger is maintained in the latter hollow fiber membrane filter, a backwashing command is issued and the scavenger is returned to the reaction tank. It is characterized by being equipped with a control device that issues commands.

(5) The method is characterized in that a powdered ion exchange resin or a powdered inorganic ion exchanger is used as the scavenger.

(Function) If most of the radionuclides contained in the radioactive waste liquid are accompanied by suspended solids, the treated liquid is recovered only by the filtering process in the first stage. In addition, if ionic radionuclides are also included, an inorganic ion exchanger is added to the filter treatment solution, the radionuclides are collected by this ion exchanger, and the ions accompanying the ion exchanger are passed through the next filter. Captures radioactive nuclides. Inorganic ion exchangers can capture very dilute ion components and have selectivity for the ions to be captured, so they can also capture ionic radionuclides at low concentrations that cannot be captured by ion exchange resins.

(Example) Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a system diagram showing the configuration of an embodiment of the present invention. As shown in the figure, this processing system is roughly divided into two zones, A and B. The A zone is a suspended radionuclide removal zone, and the B zone is an ionic radionuclide removal zone.

The main equipment in Zone A is the radioactive waste liquid collection tank (T1)
and a hollow fiber membrane filter (Fl), and the main devices in zone B are a reaction tank (Tz), a scavenger tank (T4), and a hollow fiber membrane filter (F2). In addition, the treated water tank (T3) that receives the final treated water, the sludge (suspended solids concentrate and used captured water) discharged during the backwash filter of the hollow fiber membrane filter (F1F2). The first step is to measure the radioactivity concentration of the sludge receiving tank (T5) that receives the sludge (collection agent) and the outlet water (treated water) of the hollow fiber membrane filter.
and a second radiation detector (Dl.

D2), a control device (N) is provided for determining the transfer of treated water.

Next, the radioactive waste liquid treatment method of this example will be explained.

(1) When most of the radionuclides are accompanied by suspended solids, the waste liquid collected in the collection tank (T1) is passed through the hollow fiber membrane filter (F
l) to remove most of the suspended solids.

Since the radionuclides are removed by the hollow fiber membrane filter (Fl), it is judged that there is no need for rough treatment with the radiation detector (Dl) and control device (N), and the treatment is performed by bypassing the reaction tank (T2). The water is transferred to the finished water tank (T3).

Figure 8 shows the change in radioactivity concentration at this time.

In the figure, the vertical axis is the radioactivity concentration, the horizontal axis is the collection tank T+,
The positions of the outlet of the front filter F1 (reaction tank T2) and the outlet of the rear filter F2 (treated water tank T3) are shown. Moreover, the dotted line (a) shows the case where ionic radionuclides are contained at a certain level, and the amount of radionuclides accompanying the suspended solid content is different. That is, it is clear that even if the amount of radionuclides accompanying the suspended solids increases, most of the radionuclides are captured by the filter F1 in the previous stage. The solid line indicates the concentration in each device.

(2) When radionuclides accompanying suspended solids and ion radionuclides coexist.

As shown in Figure 3, the waste liquid collected in the collection tank (T1) is transferred to the hollow fiber membrane filter (Fl) by the pump (Pl).
) to remove most of the suspended solids. However, because it contains ionic radionuclides,
Radiation detector (Dl).

The controller (N>) determines whether to transfer the waste liquid to the reaction tank (2). Collection agent is added from the collection agent tank (T4) to the waste liquid transferred to the reaction tank (T2), and the stirring device (
, M). After the ionic radionuclides are captured by the scavenger, the waste liquid (containing the scavenger) is pumped (
F2) to the hollow fiber membrane filter (F2),
The scavenger that accompanies the ionic radionuclides is removed, and the treated liquid is transferred to the treated water tank (T3) (FIG. 9).

However, the outlet water (processed liquid) of the hollow fiber membrane filter (F2)
Radioactive concentration of radiation detector (Dl) and control! If the device (N) determines that the reduction is not sufficient (Figure 10), the treated liquid is returned to the reaction tank (T2) and a new scavenger is added again, as shown in the fourth section. (Fig. 11).

(3) When the differential pressure of the hollow fiber membrane filter (Fl) increases and backwashing is performed.

With the treatment of waste liquid, the differential pressure of the hollow fiber membrane filter (Fl) (
The difference between the inlet and outlet pressures of the filter increases, resulting in backwashing. The state at this time is as shown in FIG. Sludge (concentrate) discharged from the filter (Fl) is transferred to a sludge receiving tank (T5).

(4) When the differential pressure of the hollow fiber membrane filter increases during normal batch processing (when the ion-trapping ability of the collector remains).

A collection agent is added to the reaction tank (T2) for the treated liquid transferred from the hollow fiber membrane filter (Fl), but if the collection agent still has the ability to capture ions (this is the case when the hollow fiber membrane filter (F2) is used again (as judged from the radioactivity concentration of the outlet water) (as many times as possible).The state in this case is as shown in Figure 6, and the hollow fiber membrane filter (F2)
The backwash liquid (collecting agent) is returned to the reaction tank (T2) and mixed with the next inflowing waste liquid. This state also occurs when the differential pressure of the hollow fiber membrane filter (F2) increases despite the ion trapping ability.

(5) When the quality of the water at the outlet of the hollow fiber membrane filter (F2) is poor, and when the differential pressure increases (when the scavenger does not have the ability to capture ions).

When the radioactivity concentration in the outlet water of the hollow fiber membrane filter (F2) is high, and when both the radioactivity S degree and the differential pressure become high, the hollow fiber membrane filter (F2) is backwashed and the ionic radionuclides are removed. The collecting agent that has captured the sludge is discharged to the sludge receiving tank (T5) as shown in FIG.

However, in this example, if most of the radionuclides contained in the radioactive waste liquid are accompanied by suspended matter, the treated liquid can be recovered using only the filter in the previous stage, and the ionic radionuclides coexist. In this case, an inorganic ion exchanger is added to the filter treatment liquid, and the ion exchanger captures radionuclides, and the next-stage filter captures the ionic radionuclides accompanying the ion exchanger. According to this example, the radioactivity I of the treatment liquid is higher than that of the conventional example. The degree can be reduced from 1/1000 to 1/10.

[Effect of the invention] According to the present invention, radionuclides (
It is possible to efficiently remove suspended matter (accompanied by suspended matter, ionic matter). Furthermore, since it is equipped with a control device that has a judgment function regarding transfer and processing, rational processing can be performed.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing an embodiment of the radioactive waste liquid treatment system according to the present invention, Figs. 2 to 7 are system diagrams showing the operating status, and Figs. Characteristic diagrams showing concentration changes, FIGS. 12 and 13 are system diagrams showing a conventional radioactive waste liquid treatment system. A... Suspended radionuclide removal zone B... Ionic radionuclide removal zone T1... Collection tank T2... Reaction tank T3... Treated water tank T4... Collection agent tank T5 ... Sludge receiving tank Fl ... Hollow fiber membrane filter F2 at the front stage... Hollow fiber membrane filter D1 at the rear stage ... First radiation detector D2 ... Second radiation detector M... Stirring device N...control device Pl to P4...pump Vl to v9...valve (8733) agent

Claims (3)

[Claims] (1) A collection tank for collecting radioactive waste liquid, and a hollow fiber membrane filter at the front stage connected to this collection tank and used to separate and collect suspended matter contained in the radioactive waste liquid;
A reaction tank for receiving the treated water treated by the hollow fiber membrane filter in the previous stage for further treatment, a collection agent tank for storing the collection agent to be introduced into the reaction tank, and the reaction tank. a stirring device for mixing the received treated water and a scavenger, and a subsequent hollow fiber membrane for separating and collecting only the scavenger from the scavenger-containing solution after reaction in the reaction tank. a filter, a treated water tank that receives treated water treated by the hollow fiber membrane filter in the subsequent stage, and collection of suspended solids and used waste discharged during backwashing of each of the hollow fiber membrane filters. A radioactive waste liquid treatment system characterized by being equipped with a sludge receiving tank that receives a sludge agent. (2) A first radiation detector for in-line measuring the radioactivity concentration of the treated water treated with the preceding hollow fiber membrane filter, and a signal from the first radiation detector to determine the radioactivity concentration. 2. The control device according to claim 1, further comprising a control device that determines whether the concentration is high or low and, if the concentration is sufficiently low, determines not to transfer the treated water to the reaction tank but to transfer the treated water to the treated water tank. Radioactive waste liquid treatment system. (3) A second radiation detector for in-line measuring the radioactivity concentration of the treated water processed by the hollow fiber membrane filter in the latter stage, and the radioactivity concentration is determined by the signal from this second radiation detector. and, if the concentration has not been sufficiently reduced, makes a decision to return the treated water to the reaction tank, and also instructs backwashing of the collecting agent adhering to the hollow fiber membrane filter in the latter stage. The radioactive waste liquid treatment system according to claim 1, further comprising a control device.