Performance Assessment of the Geological Disposal of Spent Fuel in a clay layer

Informations projet

N° de convention de subvention: FI2W0016

Projet clôturé

Date de début 1 Mars 1991

Date de fin 31 Mars 1995

Financé au titre de

• Specific research and technical development programme (Euratom) in the field of management and storage of radioactive waste, 1990-1994

Coût total € 316 000,00

Contribution de l’UE € 158 000,00

Coordonné par

BELGIAN NUCLEAR RESEARCH CENTRE
Belgium

Publications

Other (1)

First performance assessment of the disposal of spent fuel in a clay layer

Auteurs: MARIVOET J, VOLCKAERT G, SNYERS A, WIBIN J (SCK/CEN, Mol (BE))
Publié dans: EUR 16752 EN (1996) 205pp., FS, ECU 21.50 (euroabstract 34/954), 1996, Page(s) 205, ISBN 92-827-6124-X

Résultats exploitables

Radiological consequences of geological spent fuel disposal

Hitherto the performance assessments of geological disposal in clay layers considered essentially waste forms resulting from the reprosessing of the spent fuels. The low prics of fresh uranium and the use of mixed oxides (MOX) fuel mean that the direct disposal of spent fuel is becoming a realistic option for the nuclear fule cycle. The inventories of the various spent fuel types that can be expected to arise from the Belgian nuclear programme are estimated. Available repository concepts for the disposal of reprocessing waste are adapted to allow the placement of the large spent fuel containers. Little information is available about the behaviour of spent fuel in the conditions prevailing in clay, or about the long term behaviour of spent MOX fuels in general. Many models have been developed. However the modelling of the essential release processes requires the development of a specific near field model whuch takes into account the different corroaion rates of the various componets of the disposed spent fuel assemblies and the radiolytic oxidation of the uranium oxide matrix. An examination of the methodologies indicates that the calculations of this first assessment of spent fuel disposal in clay should focus on the analysis of the normal evolution scenario. Deterministic as well as stochastic calculations are performed. An essential conclusion of the study is that the calculated maximum dose rate is about one order of magnitude higher that one estimated for the case of high level waste disposal. On the other hand, the maximum dose is still one order of magnitude lower than the one estimated for the case of the disposal of the iodine captured at the reprossing plant. Recommendations are formulated for rhe R&D programmes as well as for more advanced performance assessments. A second performance assessment of the disposal of spent fuel in a clay layer has benn started in 1996 in the framework of the EC's SPA prject.