JPH0750196B2 - Equipment for melting and solidifying radioactive waste - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

TECHNICAL FIELD The present invention relates to an apparatus for safely evaporating, drying and melting and solidifying radioactive waste liquid or slurry for volume reduction processing safely.

[Prior art]

At nuclear facilities such as nuclear power plants and nuclear fuel reprocessing plants,
A large amount of waste liquid is generated by washing the nuclear fuel, and the ion exchange resin used for the treatment must also be discarded. Since radioactive wastes continue to accumulate year by year, it is necessary to reduce the volume to ensure their safe management and storage locations. As a treatment method, conventionally, a method of kneading and solidifying with a solidifying material such as asphalt or cement, a method of solidifying by utilizing a production reaction of an unsaturated polyester resin, has been proposed,
It has been implemented. Another treatment method is incineration by an incinerator. When this method is used, the purpose of volume reduction is achieved fairly well, but since waste ion exchange resin is difficult to incinerate as it is and it is necessary to add other combustible substances such as polyethylene, a large amount of waste gas Occurs, and the process is troublesome. Of course, the problem of disposal of incineration ash remains.

[Problems to be Solved by the Invention]

The object of the present invention is to solve the above-mentioned problems and to continuously reduce the volume of radioactive waste liquid, waste ion exchange resin, and other wastes, regardless of whether they are liquid or solid, from evaporation drying to melting and solidification. It is an object of the present invention to provide a radioactive waste treatment device that is compact and inexpensive to manufacture.

[Means for Solving the Problems]

Referring to the drawings, the apparatus for treating radioactive waste according to the present invention, as shown in FIGS. 1 and 2, stores radioactive waste such as radioactive waste ion exchange resin and cleaning waste liquid in a solidification pot 1. A cylindrical electric furnace 2 for putting and heating to evaporate and dry the waste, and the dried waste and the glass-forming substance added to the dry waste provided in the upper part of the electric furnace 2 are irradiated with microwaves and melted. Microwave generator 4 for solidification
The oven 3 to which the waveguide 41 for transmitting microwaves from the above is connected, the pedestal 51 on which the solidification pot 1 is placed, the pedestal 51 is supported, and this is moved up and down immediately before the lead of the electric furnace 2 and the vertical axis. Support board 52, which can be rotated around
Also, a radiation capable of receiving the solidification pot containing the waste to be treated in the treatment device and delivering the solidification pot containing the treated waste and enclosing the electric furnace 2 and keeping itself airtight. The oven 3 is connected to a supply pipe 31 and an exhaust pipe 32 for supplying the radioactive waste to the solidification pot 1, and the pedestal 51 has an upper end on the lower end of the electric furnace 2. It has a seal portion 53 that is in sliding contact with the portion 21 and a support board 52 on the outer peripheral portion.
Is characterized in that it has a seal portion 55 for the inner wall 54, and is supported by the springs 56, 57 on the support board 52 with cushioning properties. The radioactivity shielding box 6 is for completely preventing leakage of radioactive substances, and is closed during movement to keep the inside under negative pressure. This is because gas generated during heating by the electric furnace and microwave irradiation is exhausted to absorb thermal expansion. The electric furnace 2 is provided above one side of the radioactivity shielding box 6 as shown in FIG. Electric furnace 2 has a cooling plate around
22 is provided, a refractory material 23 is attached to the inside, the outer circumference is kept warm by a heat insulating material 24, and the whole is covered with a radiation shielding wall 25. The oven 3 that connects the electric furnace 2 and the microwave waveguide 41 has a sufficient length, and the radioactive substance is entrained in the water vapor and gas generated when the radioactive waste is heated and melted.
The inside 41 and the microwave generator 4 are prevented from being contaminated. In order to ensure the prevention of this contamination, it is advisable to provide in the oven 3 a splash shield plate made of a substance such as quartz glass or fluorine resin, which has a small inductive loss and transmits microwaves. In addition to the radioactive waste supply pipe 31 and the exhaust pipe 32, the oven 3 is preferably provided with a glass forming substance input pipe 33 and an in-vivo inspection tube (not shown). Below the electric furnace 2, a rotary lift base 7 for lifting and rotating the solidification pot 1 is provided. When melting the radioactive waste, the solidification pot 1 is rotated through the support board 52,
This is to ensure that the microwaves are uniformly irradiated. For this purpose, the pedestal 51 of the solidification pot 1 is a support plate.
By the rise of 52, the seal portion 53 (carbon ring) provided at the upper end thereof slidably contacts the lower end portion 21 (seal flange) of the electric furnace 2, and a seal is provided between the pedestal 51 and the support board 52. Department
Seal from 55 (gasket). On the rotary lift table 7, a solidification pot 1 is moved laterally by a chain conveyor of a sprocket (not shown).
A transfer carriage 8 is provided. The transfer carriage 8 is fitted to a predetermined position of the rotary lift table 7 and is provided with a shaft 71 of the rotary lift table 7.
When it rises, it is detached from the chain conveyor, and the support board 52 of the solidification pot pedestal 51 can be fixed. On the other hand, below the other side of the shielding box 6, a door 61 for loading and unloading the solidification pot 1 is provided, and above the door 61, a lifting device 9 having a lifting tool 91 is provided.

[Work]

Disposal of radioactive waste is performed as follows. First, as shown in FIG. 3, the solidification pot 1 housed in the radioactivity shielding container 12 is lifted by the lifting tool 91, conveyed to the left side of the drawing, and received on the support board 52 fixed to the transfer carriage 8. Put it on 51. The transfer carriage 8 moves further to the left, and the rotary lift 7
Stop on Next, the shaft 71 of the rotary lift base 7 extends to solidify the solidification pot 1.
Is raised and charged into the electric furnace 2, its upper end comes into contact with the lower end of the oven 3. At the same time, the seal portion 53 at the upper end of the pedestal 51 comes into contact with the lower end 21 of the electric furnace 2, and the above-described sealed state is achieved. In this state, the radioactive waste is supplied from the supply pipe 31 to the solidification pot 1. The radioactive waste may be liquid waste or solid waste such as radioactive waste liquid, waste ion exchange resin, radioactive activated carbon, filter aid, and slurry, and may be flammable or nonflammable. The radioactive waste is supplied to the solidification pot 1 placed in the electric furnace 2 through the supply pipe 31 and heated to about 800 ° C. by the electric furnace 2. By heating, water is evaporated and dried and solidified, and the organic compound is decomposed. If the radioactive waste is, for example, a mixture of the radioactive concentrated waste liquid and the waste ion exchange resin, the water is evaporated and dried by heating in the electric furnace 2, and the evaporation residue and the waste ion exchange resin remain. By heating this to a maximum of 800 ° C, most of the waste ion exchange resin is oxidized and decomposed, leaving an inorganic radioactive substance. A glass forming substance, typically crushed glass, is added to the decomposition residue through the charging pipe 33, and the microwave generation device 4
The microwave from is radiated through the waveguide 41 and the oven 3. As the glass-forming substance, in addition to the above-mentioned quartz glass, it may be a substance such as incinerated ash of paper, cloth, wood, etc., diatomaceous earth, activated clay, etc., that vitrifies, such as SiO ₂ , and melts by microwave heating Anything is fine. Therefore,
The filter aid such as diatomaceous earth used for filtering the radioactive waste can be used as it is as a glass-forming substance, and is itself a radioactive waste to be treated by the apparatus of the present invention. The radioactive waste is heated by microwave irradiation (about 1200 ° C) along with the glass-forming material,
Melts and solidifies. During this time, suction and exhaust are performed from the exhaust pipe 32 to keep the inside of the electric furnace 2 and the radiation shielding box 6 at a negative pressure. Pressure two-stage, for example, an electric furnace -100MmH ₂ O, the radioactivity shielding box should be set to -30mmH ₂ O. This pressure difference is formed by the pressure loss of the gas leaking through the seal portion. Solidification pot 1 and pedestal 5 by heating (800 ° C) in an electric furnace
The expansion due to the thermal expansion of 1 is absorbed by a cradle support spring (coil spring) 56 provided between the cradle 51 and the support board 52. When heating (1200 ° C.) by microwave irradiation is performed, the support board 52 is slightly lowered so that the pedestal support spring 56 similarly absorbs and absorbs the expansion caused by the high temperature. The structure is such that the seal portion support spring 57 constantly presses the carbon ring 53 against the seal flange 21 so that the seal can be maintained even if expansion and contraction occur. In this way, radioactive waste can be safely and continuously processed from evaporative drying to melting and solidification while maintaining the required negative pressure. The radioactive material reduced in volume by melting and solidifying is returned to the radioactivity shielding box 12 from the door 61 of the box 6 in the reverse order to the above,
Stored and stored.

【The invention's effect】

By using the apparatus of the present invention, radioactive waste can be safely melted and solidified and used for reduction. Since this device can be designed in a small size, it does not require too much equipment cost,
The processing cost is also low.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of the radioactive waste treatment device of the present invention, and FIG. 2 is an enlarged view of a part thereof. FIG. 3 is an explanatory diagram showing the entire apparatus of the present invention and the mode of operation. 1 ... Solidification pot 2 ... Electric furnace 3 ... Oven, 31 ... Waste supply pipe, 32 ... Exhaust pipe 4 ... Microwave generator, 41 ... Waveguide 51 ... Cradle, 52 …… Support board, 53,55 …… Seal part, 56,57
……Spring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsutomu Sakamoto 4002 Narita-cho, Oarai-cho, Higashi-Ibaraki-gun, Ibaraki Oarai Engineering Center, Power Reactor and Nuclear Fuel Development Corp. (72) Yuuji Harada 8 Okamura, Isogo-ku, Yokohama -9-23 (72) Inventor Tatsuo Sawaki 222-69 Fujitsuka-cho, Hodogaya-ku, Yokohama-shi, Kanagawa 222-69 (72) Shizumasa Fujimune Nagata Minamidai, Minami-ku, Yokohama-shi, Kanagawa 2-1 520

Claims (2)

[Claims] 1. An apparatus for melting and solidifying radioactive waste, which is provided in an upper portion of an electric furnace or a cylindrical electric furnace for heating the waste put in a solidification pot to evaporate and dry the waste. An oven to which a waveguide from a microwave generator for irradiating the dried waste material and a glass-forming substance added thereto with microwaves to melt and solidify is connected, a pedestal on which the solidification pot is mounted, A support board that supports a pedestal and can move the pedestal up and down along the vertical axis of the electric furnace and rotate about the vertical axis, and a solidification pot containing waste to be processed are received in the processing apparatus. In addition, it consists of a radiation shielding box that can enclose the electric furnace and keep itself airtight for delivering the solidification pot containing the treated waste, and the oven does not emit radiation. The waste supply pipe and the exhaust pipe are connected to each other, and the pedestal has a seal portion at an upper end portion which is in sliding contact with a lower end portion of the electric furnace and a seal portion at an outer peripheral portion against an inner wall of the support board. The apparatus for treating radioactive waste is characterized in that it is supported on the support board by a spring with a buffer property. 2. A rotary elevating platform for a solidification pot, a transfer platform, and a solidification pot lifting device are provided in a radioactivity shielding box, and suction means is provided at the tip of the exhaust pipe to suck the interior of the electric furnace and the electricity. The processing apparatus according to claim 1, wherein the inside of the furnace and the inside of the radioactivity shielding box connected by air leakage in the seal portion are kept at a pressure lower than atmospheric pressure.