Advances in spent fuel dry storage technology for CANDU reactors

Until recently wet storage was the only proven and economically justifiable option considered for interim spent fuel storage purposes. However, AECL's experience significantly increased over the past years due to progress made in the implementation of its own dry storage technology for spent fuel. It is based on fuel storage in concrete canisters, which rely on passive conduction to dissipate the heat and on a double steel containment system to act as a barrier. In 1989, the first CANDU 6 utility (NBEPC) opted for storage in concrete canisters instead of sequentially constructed bays. Wolsong 1 in South Korea followed with implementation of the same technology in 1991. For CANDU 3, which is presently being designed, a cylindrical basket was adopted as the receptacle for storage of spent fuel in the storage bay. This fuel basket is used for subsequent interim dry storage and could also be used for permanent disposal. This standardized approach will be used to minimize handling of individual bundles to reduce cost and susceptibility to damage. The largest cumulative cost component in a dry storage program is the construction of the concrete canisters. AECL also developed and tested the CANSTOR Module concept, an economical, concrete vault like structure that stores the same quantity of spent fuel as 22 stand-alone canisters, thus reducing the annual operating expenditures. The concept also sharply economizes on storage area requirements. 3 figs