Radioactive waste processing equipment

The radioactive waste processing equipment (ほうしゃせいはいきぶつしょりせつび, English: Radioactive Waste Management Facility) is a facility for processing to store the radioactive waste of the relatively low radioactivity level to occur with the driving of the nuclear power plant safely mainly.

These facilities are one of the supporting facilities established in a nuclear power plant and separate various materials with the radioactivity to occur in gas, a liquid, solid form routinely depending on each degree of risk and property, and the safe thing exhausts it during environment and is a facility that the dangerous thing immobilizes it in form suitable for storage in afterward and keeps it temporarily. It is that what I perform with these facilities reduces classification of the harm no damage at the point called the radioactivity and a harmful radiological volume as much as possible without being able to be reduced by neutralization and the high temperature destruction by fire unlike the waste fluid processing in the chemical factory because the radiological radioactivity is peculiar to a nuclide.

I describe the radioactive waste processing equipment of the nuclear power plant in this item [^{source 1}].

Table of contents

Principle

Each waste disposal treatment system of gas, a liquid, the solid separates waste gas occurring with generation driving safely and maintains it so that the exposure dose that the public environment around the power station receives does not exceed a value prescribed by "a guideline about the dose of radioactivity target value around the light water type nuclear reactor facilities for the generation".

Gas

The gas waste disposal treatment system reuses the available gas by classification as much as possible. The gas which I cannot use damps radioactivity by adsorbing it to active carbons, and I measure a radiation dose and gas density, and a security level exhausts only confirmed gas in environment.

The gas waste disposal treatment system is divided into two of nitrogen gas system and the hydrogen gas system with the plant of the pressurized water reactor (PWR, Pressurized Water Reactor) and is divided into three of gas derived from a turbine condenser with the plant of the boiling water reactor (BWR, Boiling Water Reactor), turbine ground seal region derived gas, the gas derived from a vacuum pump run at the time of nuclear reactor start.

PWR

The nitrogen gas processing system processes vent gas appearing from the vent gas which cover gas with nitrogen filled with the upper part of each tank rises water level, and was exhausted and each apparatus. All these are gathered by a gas collecting duct, and they pressurize a gas surge tank, and I am compressed by a gas compressor. The extra thing damps radioactivity in an active carbon-type rare gas stickup device through a dehumidification device intermittently unless I am reused as cover gas of the primary coolant storage tank and is released while watching radioactive material density.

The hydrogen gas processing system treats the purge gas of the pro-primary cooling mainly composed of hydrogen volume control tank. Xenon gas or krypton gas generated in primary coolant materials are included, and this gas damps radioactivity in an active carbon type rare gas stickup device through a dehumidification device and releases it while watching radioactive material density.

BWR

Of the air which leaked in non-condensation gas derived from a turbine condenser, and was crowded, besides, there is the purpose to prevent an explosion with hydrogen, and dilute hydrogen density in 4Vol % lower than by the steam drive of the air extractor because oxygen and hydrogen are included by the radiolysis in the nuclear reactor [¹]. After the residual heat with the effluent gas preheater, I send it to the waste gas recombination device to react will oxygen and hydrogen by a catalyst. After having lowered temperature with a dehumidification refrigerator except water in an effluent gas condenser, I adsorb xenon gas or krypton gas at an active carbon-type rare gas stickup tower and damp radioactivity. I release it from an exhaust tower after pulling it in a vacuum pump through an effluent gas particle filter to catch a minute solid particle born from gas by radioactive decay newly.

The gas derived from a turbine ground seal part becomes able to ignore radioactivity in a process to collect using the steam of the evaporator using the water of the condensation storage tank, and the gas after having returned cohesion water to the condenser in a grand steam system condenser is just exhausted from an exhaust tower.

As for the gas derived from a vacuum pump operated on the condenser side at the time of nuclear reactor start, the radioactivity is just released in the atmosphere from an exhaust tower to finish driving before steam generated in a nuclear reactor reaches the condenser saying that I can ignore it. Release radioactivity is measured in an exhaust tower and is prevented you from surpassing an environmental standard [^{source 1}].

Liquid

The liquid waste disposal treatment system manages retention, filtration, evaporation processing, ion exchange, reuse, the release.

With the plant of the pressurized water reactor (PWR), three of boric acid collection system, waste fluid processing system, the washing waste fluid system know it and are divided into three of low conduction degree waste fluid system to be called the apparatus drain with the plant of the boiling water reactor (BWR), high conduction degree waste fluid system to be called the floor drain, the washing waste fluid system. When I discharge water treated in these processing system during environment, I temporarily store it and measure radioactivity concentration and am discharged into a sample tank after having confirmed security.

PWR

The boric acid collection system attracts primary coolant extraction water, containment vessel coolant drain, nuclear reactor building coolant drain, supporting building coolant drain and I add for reuse from nitrogen waste gas processing system and accumulate in the coolant storage tank. I miss in a boric acid collection device and concentrate it and divide into distilled water and boric acid and, after retention, reuse each.

After having recruited waste fluid such as apparatus drain, floor drain, the medicine drain to a waste fluid storage tank once, the background processing system isolates it to distilled water and a concentrate by a waste fluid concentrator. The distilled water releases it and the concentrate solidifies and handles it.

The washing waste fluid system recruits washing waste fluid, hand-washing waste fluid, shower waste fluid in a washing waste fluid tray tank, and filter it with a washing waste fluid filter device, and the perwater releases it and sends it to the disarray solid destruction by fire facilities which are a pro-solid waste disposal treatment part that the concentrate burns it up and reduces it.

BWR

In the low conduction degree waste fluid system, the radiological density such as the reverse washing of a thing and the ion-exchange resin called the apparatus drain that leaked out from a pro-primary cooling pump and valve treats relatively highly high-purity waste fluid. At first I recruit it in a low conduction degree waste fluid system collection tank and I filter an insoluble particle with a filter device [²] and send the solid content to the solid waste disposal treatment system as filter sludge. I send a quality of the water standard to a condensation storage tank as make-water after confirmation except ion-formed impurities with a desalter performing ion-exchange resin processing and reuse the liquid share after the filtration.

In the high conduction degree waste fluid system, radiological density such as the reproduction waste fluid composed primarily of trivial routine duties water called the floor drain in the building and sodium sulfate at the time of the reproduction of the ion-exchange resin treats waste fluid of the low purity relatively highly. At first I send it to solid waste disposal treatment system as concentration waste fluid of the high conduction degree after recruiting it in a collection tank of the high conduction degree waste fluid system, and concentrating it by the distillation with a concentrator, and the concentration waste fluid accumulating in the concentration waste fluid storage tank, and having damped the radioactivity from a thing having a short it for the half-life. I desalt it and treat the distilled water of the concentrator and confirm that the density of radioactivity is low and drain water off to a condenser coolant flood control channel.

I treat the washing waste fluid which appears when I washed clothing used in a management area in the washing waste fluid system. At first I recruit it in a washing waste fluid system collection tank and I filter it with a filter device and send the solid content to the solid waste disposal treatment system as filter sludge. The liquid share after the filtration identifies radioactivity concentration and drains water off to a condenser coolant flood control channel [^{source 1}].

Solid

After the solid waste disposal treatment system incinerating waste fluid or sludge except high radioactive solid waste as much as possible, and having reduced it, I solidify cement in a solidification device and change it into a shape suitable for a storage. I store it in the fuel pool in the plant and a storage pool for exclusive use of the high radioactive solid waste for a long term and wait for decrement of the radioactivity and do it with extra processing without the high radioactive solid waste having high radioactivity level, and handling it with these facilities.

With the plant of the pressurized water reactor (PWR) and the plant of the boiling water reactor (BWR), it processes concentration waste fluid and acid liquid drain, disarray solid waste of the used resin, cloth and paper of the desalination tower and the noninflammability solid waste such as washing filtration concentration waste fluid, the filter for the ventilation for the used liquid together.

PWR, BWR

I make it powders, and the low thing of the radioactivity level reduces the capacity by a dryer among used resin and filter sludge in addition to concentrated concentration waste fluid and acid liquid drain with a pro-liquid waste disposal treatment waste fluid evaporator [³]. The inflammables incinerate it. The destruction by fire ash is mixed with high-performance cement that it was become these powders and I pour it on the noninflammable sloppy solid and solidify. Because the thing having high radioactivity level is not suitable for solidification facilities among used resin and filter sludge, I store it in a storage tank for the long term such as several decades and wait for the drop of the radioactivity level [^{source 1}].

Explanatory note

1. The water is condensed in the ^ turbine condenser from gas to a liquid, but many other gas ingredients are gathered using not condensing easily by a central air extraction pipe of the cooling plumbing. This is called non-condensation gas.
2. The use of the hollow thread film filter of the filter device of the ^ low conduction degree waste fluid system increases.
3. I mixed it with high-performance cement without drying concentration waste fluid in the technique in ^ before.

Source

1. ^ ^{a b c d} Makoto Kanda, other works "atomic energy plant engineering" Ohmsha, February 20, 2009 first edition first impression publication, ISBN 9784274206603

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