Generation and Classification of Radioactive Waste
Classification of Radioactive Waste
In Japan, radioactive waste is classified into two categories. One is high level waste, which remains after the recovery of uranium and plutonium from spent fuel in Reprocessing Facilities, and the other is low level waste.
Waste below the clearance level, the radioactive concentration of which is admittedly very low, is reused as general waste.
| Classification | Example | Origin of Waste | Treatment method (example) | |||
| High-Level Radioactive Waste | Canister | Reprocessing Facilities | Geological Disposal | |||
| Low Level Radioactive Waste | Waste from Power Reactors | high ↑ Radioactive Level ↓ low |
Relatively Higher Radioactive Waste |
Control Rods Core Internals |
Power Reactors | Sub-surface Disposal |
| Relatively Lower Radioactive Waste |
Liquid Waste Filters Used Equipment Expendables |
Near-surface Disposal (Concrete Pit Type) |
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| Very Low-Level Radioactive Waste |
Concrete Metals |
Near-surface Disposal (Trench Type) |
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| Waste Containing Transuranic Nuclides（TRU Waste） |
Parts of Fuel Rods Liquid waste Filters |
Reprocessing Facilities MOX Fuel Manufacturing Facilities |
Geological Disposal Sub-surface Disposal Near-surface Disposal (Concrete Pit Type) |
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| Uranium Waste | Expendables Sludge Used Equipment |
Enrichment and Fuel Manufacturing Facilities |
Sub-surface Disposal Near-surface Disposal (Concrete Pit Type) (Trench Type) Geological Disposal depending on the situation |
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| Waste below the Clearance Level | Most waste from dismantling | Sources as shown in the above | reuse/disposal as general wastes |
Radioactive Waste Generation at the Nuclear Science Research Institute
Waste materials generated in the controlled areas of each facility at the Nuclear Science Research Institute that are polluted with a radioactive material are treated as radioactive waste.
Gaseous waste from each facility is discharged after monitoring the removal of radioactive particulates using a HEPA filter. Solid and liquid radioactive waste is treated at Waste Treatment Facilities and is stored until disposal.
| Origin of waste | Common （During suspension and periodic check） |
Operation | Repair or Alteration | Decommissioning and Waste Management |
| Research Reactor Facilities | Even during suspension of operational functions, solid and liquid waste (e.g. water for hand‐washing, rubber gloves, masks, waste cloth, and vinyl acetate) is generated during checks and inspections of facilities. Gaseous waste is generated during management of air conditioning and ventilation. | Radioactive waste is generated from spent research material, sometimes including spent resins to improve water quality. |
Radioactive waste, sometimes including large items, is generated during repair or alteration. | A large amount of radioactive waste is generated during decommissioning of walls, ceilings, floors, built-in equipment, devices, and so on. |
| Fuel Material Use Facilities |
Radioactive waste is generated from spent research material. Post-irradiation examination facilities generate relatively more radioactive waste compared with other low level wastes. |
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| Radioisotope Use Facilities | Radioactive waste is generated from spent research material |
These radioactive wastes are classified as low level waste or waste below the clearance level.
Classification and division of radioactive waste from the Nuclear Science Research Institute
At Nuclear Science Research Institutes, these radioactive wastes are classified using the following table and are gathered at Waste Treatment Facilities for appropriate treatment and storage.
| Radioactive Rays | β・γ (※1) | α (※2) | |||||
| Characteristics | |||||||
| Solid Waste | Radioactivity Level | A-1 | A-2 | B-1 | B-2 | A-1 | B-2 |
| Surface Dose Rate (mSv/h) |
Under 0.5 | Over 0.5 Under 2.0 |
Over 2.0 Under 40,000(*3) |
Over 40,000(*3) | Over 37kBq(*4) Under 37 MBq |
Over 37 MBq(*4) | |
| Combustibles | IncinerationDirect Storage | Incineration Compaction-Enclose Direct Storage |
Compaction-Enclos Direct Storage |
Direct Storage | Direct Storage | Direct Storage | |
| Semi-combustibles | Incineration-Plasma Melting Direct Storage |
Incineration-Plasma Melting Compaction-Enclose Direct Storage |
Compaction-Enclose Direct Storage |
Direct Storage | Direct Storage | Direct Storage | |
| Incombustibles | Plasma Melting High-Pressure Compression Metal Melting Direct Storage |
Plasma Melting High-Pressure Compression Metal Melting Compaction-Enclose Direct Storage |
Compaction-Enclose Direct Storage |
Direct Storage | Direct Storage | Direct Storage | |
| Liquid Waste | Radioactivity Level | A未満 | A | B-1 | B-2 | - | |
| Division of the Surface Dose Rate (mSv/h) |
Under 0.37 | Over 0.37 Under 37 |
Over 37 Under 37,000 |
Over 37,000 Under 370,000 |
Over 1.85 | ||
| Inorganic waste | Dilution-Drainage Evaporation |
Dilution-Drainage Evaporation |
Evaporation | Evaporation | Direct Storage after solidification at generating facilities | ||
| Organic waste | Treat as solid waste after solidification | Direct Storage after solidification at generating facilities | |||||
| Gaseous Waste | Gaseous waste is discharged after purification using a filter. | ||||||
*2: Mainly waste that is polluted with radioactive material that emits alpha rays （Natural uranium and thorium are excluded）.
*3: Judged at a position 50 cm away from the container.
*4: Judged by the quantity of radioactivity per 20 ℓ in a container.
