WASTE MANAGEMENT SAFETY

The main objective in the management of radioactive waste is to ensure the protection of the public, workers and environment by isolating all hazardous material from the biosphere. Technologies are required for the various stages of waste management, i. e. the handling, temporary storage and long-term disposal. To ensure safety, the handling, storage and disposal of all waste materials arising from all plant operations is carefully managed according to the degree of hazard.

Wastes are obtained from all stages of the fuel cycle, from uranium extraction, refining, reactor operation and decommissioning. Waste can arise in gaseous, liquid or solid forms. Some of these waste products are radioactive with varying degrees of activity. They include low-level radioactive spoil from uranium mining residues and uranium and plutonium residues from fuel fabrication.

Reprocessing plant operations produce waste of medium level of radioactivity, arising from various waste streams, and hulls from residual cladding and support materials from fuel elements. There are other low-level wastes from reprocessing operations, including miscellaneous items such as gloves, containers, etc.

The reactors produce highly radioactive waste in the form of spent fuel; this issue is discussed further in the next section. They also produce inert gas (waste) from fractured fuel elements, liquid waste in the form of tritiated water and solid waste, e. g. filters and resins. The latter arise from water treatment plants; these resins are used to clean up primary system fission or corrosion products.

Decommissioning also produces mildly radioactive structural materials.

Drainage water from reactor support systems, fluids from decontamination operations and ion-exchange resins in the form of liquid effluents are collected in tanks. These effluents are then categorised and distributed to various sub-systems depending on their activity or impurity content.

Low-level effluents are discharged under controlled conditions back into the reactor plant. Solid low-level wastes may be compacted and then encased in stainless steel drums. Intermediate effluents may be treated with ion-exchange filters or evaporated, with the purified water returned to the reactor coolant system. Active resins or concentrated active liquids are stored in tanks, to allow for decay of the shorter lived isotopes, before being sent for waste treatment. Solid wastes such as filter resins evaporation residues are treated and then cast in concrete.

More details on the scale of the global nuclear waste management issue and present and possibly future containment practices are given in Chapter 6.

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