Operational experience of UBS for spent fuel verification and optimum application

IAEA and EURATOM have applied UBS for the verification of spent fuels which have been stored in spent fuel pond of THORP since 1994. Application and development of this special sealing system, UBS could establish dual containment and surveillance system for spent fuel which have been stored long-term for reprocessing in the future. It is expected to reduce the verification time of the spent fuel which have been stored long-term under safeguards and also increase verification effectiveness. Compared with NDA using gamma detector, this save to maximum 80% of verification time in THORP. On the basis of this experience it is reviewed the possibility of UBS application to the CANDU spent fuel pond which produce and store a lot of spent fuel at present