JPS6189596A - Method of disposing concrete structure in tritium treating facility - 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 [Field of Industrial Application] The present invention relates to a method for disposing of concrete structures in tritium handling facilities.

[Prior art]

Tritium (tritium) T is an isotope of hydrogen H. At facilities that handle tritium, such as Mito, nuclear fusion research facilities, and spent nuclear fuel reprocessing facilities, measures are taken to prevent this tritium T from leaking outside. . This tritium Tfl
By replacing one H atom of , H, and O, triple water takes the form of HTO, but since this triple water is 9 water, the above-mentioned measure to prevent leakage to the outside is necessary to keep it as a liquid. Alternatively, measures are taken to make the areas where tritium is generated airtight to prevent it from evaporating and leaking outside of nuclear reactor facilities.

By the way, currently there is almost no disposal and demolition of each of the above facilities, so it is sufficient to prevent the leakage of tritium at each facility as described above, but in the future, it will be necessary to dispose of each of the above facilities and, therefore, to dismantle the concrete structures that make up the facilities. It is expected that the amount of demolition and disposal will increase.

[Problem that the invention seeks to solve]

If the concrete structures that make up each of the above facilities are radioactively contaminated, what will happen when they are demolished? Radiation MJ - 1 animal
``Things'', L-3R, so they must be collected and stored permanently under human control.

By the way, in the research carried out by the present applicant, it was discovered that triple water (HTO), which exists in the air as extremely small amounts of water vapor, was found to be free water in concrete such as floors and walls. Alternatively, they discovered a phenomenon in which crystallized water penetrates and becomes fixed in concrete by replacing it with crystallized water. Therefore, upon demolition, these tritium-contaminated concretes
Even if there is no contamination with other nuclides or activation by neutrons, permanent storage is required as described above, but permanently storing all the concrete structures that make up the tritium handling facility would be costly due to demolition. The problem is that the amount is enormous.

In view of the above circumstances, this invention aims to reduce as much as possible the amount of waste that must be permanently stored when a tritium handling facility is dismantled and disposed of.

(f14] Means for solving the problem) In order to solve the above problem, the present invention crushes a concrete structure, heats the crushed concrete mass, and evaporates the water in the concrete mass. , collects evaporated water,
It was decided to discard the heated concrete mass.

(Effect) As water is removed from the concrete mass by heating, tritium water (triple water) is also removed, and the concrete mass ceases to be a radioactive substance.

The evaporated water, including tritiated water, is collected, but only this collected water is treated as radioactive waste.

〔Example〕

The drawing is a system diagram of a concrete lump processing apparatus, in which a high-frequency heating furnace 1 is used as a heating device.

The high-frequency heating furnace 1 is composed of a furnace body 2, a high-frequency generator 3, a high-frequency horn 4, etc. The furnace body 2 has an airtight concrete loading door 2&, a concrete discharge door 2b, and a container 5P+3 housed inside. concrete mass 6 is heated. The concrete discharge door 2b is of a hinge type that opens downward, and a concrete lump receiver 7 is placed below it.

A steam exhaust pipe 8 is connected to the upper part of the furnace body 2, and a moisture collector 9 is connected in the middle through an airtight joint 0. Valves 11 are provided on both sides of the pipe to collect moisture. The steam exhaust pipe 8 on the downstream side of the vessel 9 is lowered into the water 41ii112 for absorbing moisture, and the suction pipe 13 is raised from the upper space of the water Wj12 to the suction side of the suction pump 14. An exhaust pipe 15 connected to the discharge side is connected to an exhaust tower (not shown). Note that a monitoring filter 16 is provided in a portion of the suction pipe 13 immediately before the suction pump 14 .

To explain the operation of the embodiment, a concrete structure constituting a tritium handling facility is dismantled, crushed into concrete blocks of appropriate size, and these are placed into the furnace body 2. When the concrete block 6 is heated by the high-frequency heating furnace 1, the water (free water or crystalline water) that has permeated and fixed inside is evaporated, becomes water vapor, passes through the steam exhaust pipe 8, and is captured by the moisture collector 9. I can gather.

The exhaust gas from which moisture has been removed is sucked by the suction pump 14 and sent to the exhaust tower, where it is discharged to the atmosphere.

Note that while the apparatus is in operation, the monitoring filter 16 is replaced, for example, once every hour to confirm that the tritium concentration in the exhaust gas is below the permissible concentration.

The tritium concentration may be measured using a liquid scintillation counter for tritium bonds in the filter 16, for example.

Further, the heating condition is preferably maintained at a temperature of 500° C. or higher for several hours, for example. This completely separates free water and crystallized water in concrete.

Since the concrete lump from which moisture has been removed by heating as described above is no longer a radioactive material, it is taken out into the concrete lump receiver 7 and disposed of as general waste.

As the moisture collector 9, it is preferable to use one filled with molecular sieve (trade name of Daisoko Futsuishi) or other water-absorbing substance. The moisture collector 9, such as a molecular sieve, that has trapped moisture is disposed of as radioactive waste.The heating method used in the embodiment is high frequency heating, but electric heating and other various heating methods can be used.

In addition, in the embodiment, the water vapor evaporated from the concrete mass is collected twice in the moisture collector 9 and the water tank 12, but as long as the concentration is below the allowable level, only the water tank 12 may be used. In addition, as long as it is confirmed through monitoring that the water vapor itself coming out of the heating furnace 2 is below the permissible concentration, the heating furnace 2 is
The water vapor may be discharged directly to the atmosphere.

〔Effect of the invention〕

According to the present invention described above, the concrete mass is heated to evaporate and remove the free water or crystal water that has permeated and fixed inside, so the concrete mass contaminated with tritium is disposed of as general waste. Only the collected water needs to be disposed of as radioactive waste.

Therefore, compared to the case where all the concrete structures that make up the tritium handling facility had to be treated as radioactive waste, the amount of waste that must be permanently stored as radioactive waste is significantly reduced, and therefore, the amount of waste that must be permanently stored as radioactive waste is significantly reduced. The cost of dismantling the facility can be significantly reduced.

[Brief explanation of the drawing]

The drawing is a system diagram of a concrete lump processing apparatus showing an embodiment of the method of the present invention. 1... High frequency heating furnace, 2... Furnace body, 6
... Concrete lump, 8 ... Steam discharge pipe, 9 ... Moisture collector, 12 ... Water tank, 13 ... Suction pipe , 15...exhaust pipe.

Claims (1)

[Claims] The method is characterized by crushing a concrete structure in a tritium handling facility, heating the crushed concrete mass to evaporate water in the concrete mass, collecting the evaporated water, and disposing of the heated concrete mass. Disposal method for concrete structures in tritium handling facilities.