Final storage of spent nuclear fuel - KBS-3

An updating of an earlier report on the final disposal of spent nuclear fuel in Sweden is presented. The report is a summary of a large number of project reports, of which only part appears in the open literature. Four volumes contain respectively:(I) defines the scope of the study and goes on to outline a system based on reactor site cooling of fuel, then transport to an intermediate storage (40 years) plant. After such a period the spent fuel shall be encapsulated in copper and put into final storage in deep (ca 500 m) geologic strata. (II) discusses fractures and ground water movements at different geologic sites in Sweden. Ground water chemistry is discussed in relation to the corrosion of cannister systems planned. The history of Scandinavian bedrock is related and possible evolutions for the next 1 Myears, the period of interest for containment of spent fuel. (III) discusses the barriers set up against dissipation of radioactive species from depositories. Bentonite is envisaged as acting both as a buffer material and as a filler that will swell when humid. Corrosion rate of the copper canisters is estimated to give 1 million years before the first barrier is broken through. The chemistry of materials leached from fuel into the ground water within bedrock is discussed. Radiation and health effects are discussed on the time scale given by the barrier system used. (IV) discusses general safety principles, and goes on with a discussion of site-specific data. The overall radiological safety of the concept, both during operation and in the sealed repository is discussed. The final conclusion that a final repository for spent nuclear fuel can be built within Sweden with known technology and sufficient safety. (author)