Waste Technology Section
Predisposal includes all of the steps carried out prior to disposal:
- Storage; and
Characterization of waste is also an essential predisposal activity that is common to all of the above steps.
Pre-treatment includes any operations prior to waste treatment, to allow selection of technologies that will be further used in processing of waste (treatment and conditioning), such as:
- Chemical adjustment; and
Treatment of radioactive waste includes those operations intended to improve safety or economy by changing the characteristics of the radioactive waste. The basic objectives of treatment are:
- Volume reduction;
- Radionuclide removal from waste; and
- Change of physical and chemical composition.
Conditioning covers those operations that produce a waste package suitable for handling, transportation, storage and/or disposal. It may include:
- Immobilization of the waste;
- Enclosure of the waste in containers; and, if necessary
- Provision of an overpack.
Immobilization refers to the conversion of waste into a waste form by solidification, embedding or encapsulation. Common immobilization matrices include cement, bitumen and glass.
Storage of radioactive waste involves maintaining the radioactive waste such that retrievability is ensured and confinement, isolation, environmental protection and monitoring are provided during storage period.
Radioactive waste may be stored as raw, pre-treated, treated or conditioned waste. The purpose and duration of storage vary depending on the objective, which can be, for example:
- decay of waste for authorized discharge or for clearance after decay; or
- further processing and/or disposal at a later time.
Transportation refers to the deliberate physical movement of radioactive waste in specially designed packages from one place to another. For example, raw waste maybe transported from its collection point to centralized storage or processing facility. Conditioned waste packages maybe transported from processing or storage facilities to disposal facilities.
The most common modes of transport include the use of trucks, tankers, trains and barges. To protect people, property and the environment, transport is carried out in special packages to and from nuclear facilities in accordance with internationally accepted regulations. Read more on safety aspects of transportation.
Characterization of radioactive waste is an important aspect at every stage of pre-disposal management. By knowing the characteristics, it is possible to establish further adjustment, treatment, conditioning, or suitability for further handling, processing, storage or disposal.
Waste characterization involves determination of the physical, chemical and radiological properties of the waste.
Predisposal steps Photo essay