Canadian Experience with the Dry Storage of Used CANDU Fuel

Abstract

In 1974, Atomic Energy of Canada Limited (AECL) began a demonstration program to investigate the feasibility of dry storing used fuel in concrete canisters (CCs). Because of the success of that program, CCs have been licensed for the dry storage of used CANDU fuel in Canada. Today CCs are being used at three reactor sites to store about 27 000 ( 390 Mg U) of used CANDO fuel bundles. Most of the fuel being stored in the CCs has been previously cooled in water pools for periods greater than 10 years.The largest quantity of fuel in dry storage in Canada is at the site of the decommissioned Douglas Point reactor. The peak and average burnups of that fuel are about 832 and 667 GJ/kg O, respectively, and the peak fuel temperature in the CCs was about 125 degrees C. The radiation dose experienced by the operators while loading the CCs was 0.25 mSv per canister. In 1978, AECL initiated a research program to investigate the long-term behaviour of used fuel ( both undefected and defected) during dry storage. The program is funded jointly with Ontario Hydro, a provincial government electricity-generating utility, and is scheduled to continue beyond the year 2000. Intentionally defected fuel that has been stored for about five years in 150 degrees C moisture-saturated air has been examined recently. The results of the examination revealed no significant degradation of the fuel or cladding.Ontario Hydro has also designed a multipurpose concrete integrated container (CIC), with a capacity for 384 CANDU fuel bundles, for the dry storage, transportation and, possibly, the final disposal of used fuel. Two CICs are scheduled to be loaded with used fuel in 1988 for demonstration purposes, and two more are planned for construction in 1989 for transportation tests.