Letter of Compliance Studies

The UK Radioactive Waste Management Directorate (RWMD) issue Letters of Compliance (LoCs) to waste producers to give them assurance that packaged intermediate level wastes will meet requirements for disposability if and when a UK waste repository is constructed. The LoCs are only issued after a detailed assessment of the packaging proposals covering a wide range of criteria.

For radiological studies, the requirements are principally for a Nature & Quantities study, a Data Recording study and a Criticality Compliance Assurance document (CCAD). Depending on the stage of submission, these may be combined into a single document of issued as separate documents.

I have been involved in production of the radiological LoC documents, and supporting documents, for many years, both as author on behalf of the waste producers and as assessor on behalf of RWMD.

Examples of specific project involvement include:

Trawsfynydd Fuel Element Debris (FED) packaging, in particular the Data Recording and CCAD documents. The justifications were entwined with design of the FED assay system, and were a challenge given the possibility of fragments of fuel being present along with general contamination arising from the storage periods in the fuel cooling ponds.

Hunterston sludge and resin packaging: I wrote supporting documents for estimation of radionuclide inventories & radiological properties, and justification of procedures for data recording.

Sizewell B dry fuel storage studies: I was deeply involved in estimation of the radionuclide inventory and radiological properties of a hypothetical study for dry packaging of PWR fuel.

Berkeley Active Waste Vaults: I have been involved in LoC supporting work over a period of around ten years, over which time the project has been re-invented many times. Challenges arose from the very heterogeneous waste form, the lack of detailed information on compositions of some of the wastes, the lack of radiochemical data and many changes to the process design. The assay system changed radically over the period of my involvement (I like to think that I influenced it for the better) which impacted on the way in which data were to be interpreted.

Assessment of LoC submissions to RWMD, including graphitic wastes from Windscale Pile 1 and Ionsiv resins