Waste management

Radioactive materials for which no further use is foreseen, and with characteristics that make it unsuitable for authorized discharge, authorized use or clearance⁽¹⁾ from regulatory control are called radioactive waste. Of course, measures to prevent or minimize the generation of radioactive waste have to be put in place in the planning and implementation of all the activities that have the potential to generate radioactive waste.
The radioactive waste arising from nuclear power plants and from research reactors is diverse and varied in nature and it encompasses a broad range of radionuclides, half-lives, activity concentrations, volumes, and physical and chemical properties. They may include: spent ion exchange resins, filters, activated metals, liquid and gaseous effluents, irradiated experimental components, spent fuel declared as waste and waste from decommissioning.
It is paramount that nuclear waste has to be properly processed to make it safe for disposal. A key feature of the predisposal management of radioactive waste from nuclear power plants and research reactors is the interdependence between the steps in the processes of predisposal management and the disposal within a national framework for waste management.
Predisposal management of radioactive waste covers all steps in the management of radioactive waste from the assessment of potential and actual waste arisings, the evaluation of the management options, its generation, up to (but not including) its disposal, including waste processing, storage and transport.
Before selecting a waste processing strategy, it is essential to know and understand the waste source and rate of waste generation, as well as the amounts and characteristics of the waste.
Characterization is a step that provides information on the physical, chemical and radiological properties of the waste, which helps identify appropriate safety requirements and

potential processing options. It also ensures compatibility and compliance with accepted storage and disposal criteria.
There are three main steps in the processing of nuclear waste: pre-treatment, treatment and conditioning. Pre-treatment prepares the waste for processing and may include sorting and segregation to separate out contaminated items from non-contaminated ones. Sometimes it is necessary to reduce the size of the waste by, for example, cutting or shredding it to optimize its downstream processing. Decontamination techniques reduce the volume of waste requiring treatment, which in turn minimizes the cost of its disposal.
The next step is treatment. Generally, treatment processes aim to reduce the volume by separating out the radioactive component from the bulk waste, often changing the waste’s composition. A variety of waste treatment processes are available depending on the nature of the waste and the waste acceptance requirements of the chosen disposal site. Two common treatment techniques are: incineration of solid waste and evaporation of liquid waste.
Treatment contributes to enhance waste safety and reduce the costs of further management phases, such as storage or disposal.
The third step in the process is conditioning, which involves those operations that transform radioactive waste into a safe, stable and manageable form suitable for subsequent activities such as handling, transport, storage and disposal. Conditioning techniques are designed to slow the release of radionuclides from the disposed waste package into the environment. To condition waste for disposal, it is often encapsulated or solidified in cement, bitumen or polymer for low level and intermediate level activity waste, and glass for high level activity waste, in accordance with the waste acceptance criteria, or overpacked into special containers.

The conditioned waste are ready for storage, which refers to the temporary placement of radioactive waste in a facility where appropriate isolation and monitoring are provided. In this view, storage is an interim activity performed with the intent to retrieve the waste later for the proper waste management option.
Waste management options such as clearance from regulatory control, for authorized use, for processing, for authorized discharge in the case of effluent and authorized disposal, in compliance with the conditions and acceptance criteria established by the regulatory body, should be used as far as practicable, with preference given to recycling, reuse and clearance from regulatory control.
The ultimate goal of predisposal management of radioactive waste that is not to be cleared, discharged, recycled or reused is to make the waste suitable for disposal (or for storage if no disposal facility is available). This implies that each waste package, that is made of the final waste form and the waste container, has to comply with the waste acceptance criteria⁽²⁾ of the disposal facility (or with the operational safety requirements of the storage facility).
National governments have to make provisions for the safe management and disposal of radioactive waste arising from facilities and activities. Such provisions should be included as essential elements of governmental policy and of the corresponding strategies. Then the regulatory body and organizations operating or planning to operate transport services, storage facilities and disposal facilities should be consulted in deciding which types of pretreatment, treatment and conditioning will be necessary. When the disposal facility or acceptance requirements for disposal are not yet available, waste acceptance criteria should be specified on the basis of reasonable assumptions about the final disposal option.