What are the different nuclear wastes and their management?

Answer: Six classes of wastes are derived and used as the basis for the IAEA classification scheme and the type of disposal varies accordingly. To deal with wastes, management systems are required for related processes and activities such as: (a) Waste generation; (b) Waste characterization; (c) Use of controlled discharges; (d) Clearance; (e) Packaging strategies; (f) Design and manufacture of containers; (g) Handling of waste packages; (h) Safety assessment; (i) Regulatory authorization (e.g. licensing).

Classification of radioactive waste may be helpful in planning a disposal facility and at any stage between the generation of raw waste and its disposal.

 

Background

Six classes of wastes are derived and used as the basis for the IAEA classification scheme and the type of disposal varies accordingly:

- Exempt waste (EW): waste that meets the criteria for clearance, exemption or exclusion from regulatory control for radiation protection purposes …

- Very short lived waste (VSLW): waste that can be stored for decay over a limited period of up to a few years and subsequently cleared from regulatory control.

- Very low level waste (VLLW): waste that does not necessarily meet the criteria of EW, but that does not need a high level of containment and isolation and, therefore, is suitable for disposal in near surface landfill type facilities with limited regulatory control.

- Low level waste (LLW): waste that is above clearance levels, but with limited amounts of long lived radionuclides. Such waste requires robust isolation and containment for periods of up to a few hundred years and is suitable for disposal in engineered near surface facilities.

- Intermediate level waste (ILW): waste that, because of its content, particularly of long lived radionuclides, requires a greater degree of containment and isolation than that provided by near surface disposal. However, ILW needs no provision, or only limited provision, for heat dissipation during its storage and disposal. Therefore, waste in this class requires disposal at greater depths, of the order of tens of meters to a few hundred meters.

- High level waste (HLW): waste with levels of activity concentration high enough to generate significant quantities of heat by the radioactive decay process or waste with large amounts of long lived radionuclides that need to be considered in the design of a disposal facility for such waste. Disposal in deep, stable geological formations usually several hundred meters or more below surface is the recommended solution.

It will help in devising waste management strategies; in planning and designing waste management facilities; in assigning radioactive waste to a particular conditioning technique or disposal facility, in the development of legislation and the establishment of regulatory requirements and criteria, by defining operational activities and in organizing the work to be undertaken with the waste; by providing a broad indication of the potential hazards associated with the various types of radioactive waste; by facilitating record keeping and for communication.

Some countries are considering managing the final storage so that it could be reversible.