Background

These radionuclides include various fission products and minor actinides, but little or no uranium and/or plutonium as these actinides have been removed by the PUREX process.

Subsequent decommissioning of these nuclear facilities will generate significantly larger volumes of liquid wastes from the decontamination of plant/equipment. Although decontamination liquors are largely restricted to nitric acid, citric acid and sodium hydroxide as these materials are compatible with the materials of construction, other proprietary chemicals are used when necessary. This variety of liquids results in various treatment techniques some of which render these treated liquid unrecyclable adding to the waste management impact. Solid materials from these treated liquids require further treatment before being considered for disposal.

An international research collaboration:
developing nano-structured hybrid materials

Consistent, routine, low cost preparation of nano-materials/nano-structured materials has eluded scientists to date and therefore their true potential has not been realised. Our programme will develop nano-structured hybrid materials that have high affinities for various fission products and minor actinides that can function in acid and alkaline solutions and require minimal down-stream treatment prior to disposal.

Key features

There are 3 key features of this ambitious programme:

1. Preparation of low cost materials that are stable in acid or alkali solutions and have high capacities for target radionuclides to minimise the quantity needed to treat these liquid wastes.
2. Selecting the appropriate functionality of the nano material to discriminate between candidate radionuclides and non radionuclides that will be found in spent decontamination liquids.
3. In-build a solid/liquid separation technology; one technique that will be incorporated is a ferrite core thus allowing the separation to be accomplished by a magnetic field.

It is envisaged that these nano materials could be used in-situ thus preventing a build up of radioactivity in the liquid.

The net result

The net result is an integrated clean up process that removes contamination in situ but also and equally important produces an end-product that can be accommodated into existing encapsulation techniques such as cementation or vitrification for final disposal.

Cost effective, efficient and safe management of wastes are primary requirements for the nuclear industry per se. These wastes whether solid, liquid or gaseous arise from every stage of the nuclear fuel cycle and are treated to ensure they comply with stringent regulatory standards before final disposal into the environment.

The industry is keen to adopt any process/technology that can reduce costs, environmental impact whist maintaining safety standards.