JPS6013159B2 - How to dispose of liquid scintillator waste - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for the primary treatment of liquid scintillator waste containing radioactive elements, and its purpose is to perform special treatment on liquid scintillator waste so that it is easy to transport and store and is easy to dispose of. The objective is to produce a solidified material containing a suitable radioactive substance.

In laboratories and hospitals that handle radioactive organic materials, liquids containing radioactive organic materials are generated as waste.

For example, when measuring the radioactivity of organic matter containing radioactive elements at 3 days or 1° C., liquid scintillator waste containing these is produced. By the way, since such liquid scintillator waste 2 contains flammable organic solvents such as toluene, benzene, and xylene, it is highly flammable, making it difficult to transport and store it, and the radioactive waste treatment system is difficult to handle. Because they are not yet fully equipped, each facility is forced to store them.

However, it is clear that in such facilities, storing highly flammable liquid scintillator waste is extremely dangerous and undesirable.

3 The present invention has been made from this point of view, and uses a simple and safe method to convert waste containing radioactive liquid scintillator waste into a non-flammable and safe inorganic material that is easy to transport and store. A method for binding to solid objects is provided. 3 The method of the present invention will be explained with reference to the drawings. In the drawings, 5 is a solid-liquid separator, 8 is a closed liquid combustion furnace, 12 is a gas-liquid separation tank, and 15 is a solid-liquid separator.
is a non-condensable gas immobilization section, 16 is a deodorizing tower, 19
indicates a closed solid combustion furnace.
4. Liquid scintillator waste containing radioactive elements such as 14C and 14C to be subjected to primary treatment enters the solid sedimentation tank 2 from line 1A, where most of the radioactive organic solids contained therein settle out. The separated liquid waste as a supernatant containing small amounts or fine radioactive solids is transferred through line 3 to solid-liquid separator 5 (eg, centrifuge, filtration machine, etc.). In these solid sedimentation tank 2 and solid-liquid separator 5, the solids separated from the liquid are led to the tank 17 through line 4 and line 7, respectively. Although a solid-liquid separation section is provided to separate fine and coarse solids in the liquid waste, this is not always necessary, and in some cases the raw liquid can be introduced directly into the combustion furnace 8. The liquid separated from the solid-liquid separator 5 is led to the combustion furnace 8 through a line 6 and an electromagnetic automatic opening/closing valve 6' attached thereto.

This combustion furnace 8 is a closed type equipped with a combustion burner, and the liquid scintillator waste is either left as it is or is combusted with other fuel as a combustion agent.The combustion gas (main component is carbon dioxide gas and water vapor (including N02 in some cases) is led through line 9 to the cooler iol, where it is cooled to less than 100 qo, usually to room temperature (20 to 300 C). By cooling, the water vapor contained in the combustion gas is condensed, but this condensed water and non-condensed combustion gas are then led to a gas-liquid separation tank 12 through a line 11, where the condensed water undergoes non-condensed combustion. The separated non-condensable combustion gases are sent to the immobilization section 15 via line 13, while the condensed water is sent to the storage tank 23 via line 14. The combustion gas is passed through absorption towers 15-a, 15-b, and 15-c containing fixing agents according to its components.
, 15-d, during which moisture, carbon dioxide, nitrogen dioxide, sulfur and halogen contained in the combustion gas are fixed and removed.

That is, the moisture absorption tower 15-a filled with a desiccant such as calcium chloride or silica gel absorbs water, and the carbon dioxide absorption tower 15-b filled with a carbon dioxide absorbent such as soda lime or caustic soda absorbs carbon dioxide and zeolite. Nitrogen dioxide is absorbed and fixed in each filled nitrogen dioxide absorption tower 151c. Nitrogen monoxide contained in combustion gas is similarly adsorbed and immobilized using a suitable adsorbent such as zeolite, but this is not very efficient, so ozone and
It is best to convert it into nitrogen dioxide by adding it. When halogen and sulfur are contained in the combustion gas, they are fixed and removed in an absorption tower 151d filled with an adsorbent such as activated carbon or alumina. Also, in the unlikely event that carbon monoxide is generated due to incomplete combustion, Hof. It can be passed through a packed column of karite to convert it into carbon dioxide and fix it. In consideration of safety, the combustion gas discharged from the immobilization section 15 passes through a deodorizing tower 16 filled with activated carbon, and then is discharged into the atmosphere from a line 29.

On the other hand, the solid waste separated from the solid-liquid separation section is stored in a storage tank 17, and then guided through a line 18 and an electromagnetic switching valve 18' to a closed solid combustion furnace 19, where it is burned. . As in the case of liquid combustion, the combustion gas flows through line Z20.
It is cooled by a cooler 21 and guided to the gas-liquid separation tank 12 via a line 22, where it is separated into gas and liquid together with the cooled material from the line 11. Further, solid bulk animal and plant waste containing radioactive materials can be directly supplied to the solid combustion furnace 192 from the line lb and burned. The cooler 21 can also be combined with the cooler 10.
The condensed water separated in the gas-liquid separation tank 12 is transferred to the line 14
The water is collected in a storage tank 23 through a line 24 and enters an immobilization section 25 where it is mixed with a coagulant such as calcined stone or cement introduced through a second line 26 and solidified. In this case, the ash produced in the combustion furnace 19 is also sent from a line 22 via a storage tank 23 to a condensate fixation device where it is solidified.
3 In the method of the present invention, in order to ensure safety, a radioactivity monitoring device 28 is attached to the line 29 from the deodorizing tower 16, and this device is equipped with an electromagnetic automatic opening/closing valve 28'.
When the radioactivity exceeds the specified amount, the atmospheric communication side of the three-way valve 28' is automatically closed, and the line 30 is electrically connected to the
When the transportation side connected to the first line is opened, the pump 31 is activated, and the combustion gas is circulated through the closed system between the line 30 and the immobilization section without being released into the atmosphere. At the same time, valves 6' and 18'
will also be closed. According to a preferred embodiment of the present invention, in the immobilization section, a pair of each absorption tower is prepared in advance, and two series of immobilization sections are prepared. In reality, one series of fixed sections is used. Then, as shown in the drawing, the unimmobilized exhaust gas from the immobilization section is released into the atmosphere through a line equipped with a radioactivity monitoring device 28. When the radioactivity exceeds a specified amount, the radioactivity monitoring device is activated to automatically supply the pseudo-condensed gas from the gas-liquid separation process to the immobilization section of another system.
In addition, this separate system (i.e.,
Switching of the supply of 9E condensate gas to the immobilization section (containing fresh immobilization agent) is carried out by an electromagnetic valve moved with a radioactivity monitoring device. The use of this immobilization section containing fresh immobilization agent prevents more radioactivity from being released into the atmosphere without shutting down the apparatus. In addition, by replacing each used absorption tower with a new one, it is possible to prepare an immobilization section consisting of fresh solidification agent. The method of the present invention includes:
It is extremely effective as a pollution-free primary treatment method for liquid scintillator waste containing radioactive organic matter in solid or dissolved form.Moreover, the radioactive organic matter is completely mineralized and solidified, and the solid matter produced is radioactive. is significantly concentrated compared to the treated raw material.

In other words, this solid material has a reduced volume and is non-flammable, and since the produced solid material is completely mineralized, it is easy to store and safe to transport. This is extremely effective as a secondary or final treatment method for radioactive materials.

[Brief explanation of drawings]

The drawing is a flow sheet for carrying out the method of the invention. In the figure, numeral 5 is a gas-liquid separator, 8 is a closed combustion furnace, 12 is a gas-liquid separation tank, 15 is a non-condensable gas fixation section, 1
Reference numeral 6 indicates a deodorizing tower, and 19 indicates a closed solid combustion furnace. 〇

Claims (1)

[Claims] 1. In treating liquid scintillator waste, (a) a step of burning the waste in a closed combustion furnace;
(b) A step of cooling the generated combustion gas and condensing the water vapor contained therein, (c) A step of separating condensed water and non-condensable gas, (d) A step of separating the separated non-condensable gas into the combustion gas. A step of supplying a non-condensable gas to one of the two non-condensable gas fixing sections consisting of a fixing agent that chemically or physically binds to the contained directional component; (e) non-condensable gas in the gas fixing section; The step of immobilizing (f) the above (c)
A step of supplying the condensed water separated in step (e) to the condensed water immobilization section, (g) a step of immobilizing the condensed water in the condensed water immobilization section, (h) unimmobilized water from the step (e) above. a step of releasing exhaust gas into the atmosphere through a line equipped with a radioactivity monitoring device, and when the radioactivity of the unfixed exhaust gas exceeds a specified amount, the radioactivity monitoring device operates to The non-condensable gas from the process described above (
A method characterized in that the non-condensable gas is supplied to a separate series of non-condensable gas fixing sections in step (d). 2 When processing liquid scintillator waste, (a
) a step of separating solids contained in the liquid; (b) a step of burning the separated solids in a closed combustion furnace;
(c) burning the liquid after separating the solids in a closed combustion furnace; (d) burning the combustion gases produced in (b) and (c) separately or in combination and cooling them; (e) separating the cooling product consisting of condensed water and non-condensable gas into condensed water and non-condensable gas; (f) separating the separated non-condensable gas therein; a step of supplying a fixing agent that chemically or physically binds to a radioactive component to one of the two non-condensable gas fixing sections; (g) fixing the non-condensable gas in the gas fixing section; (h) the step (
e) supplying the condensed water separated in step (i) to the condensed water immobilization section; (i) immobilizing the condensed water in the condensed water immobilization section; (j) unimmobilized water from the step (g) above; a step of discharging the exhaust gas into the atmosphere through a line equipped with a radioactivity monitoring device, and when the radioactivity of the unfixed exhaust gas exceeds a specified amount, the radioactivity monitoring device is activated to perform the step (e) above. The non-condensable gas from the process of (f
) A method characterized in that the non-condensable gas is supplied to a separate series of non-condensable gas immobilization sections in the process.