CONSTOR STEEL CONCRETE SANDWICH CASK CONCEPT FOR TRANSPORT AND STORAGE OF SPENT NUCLEAR FUEL

A spent nuclear fuel transport and storage sandwich cask concept has been developed together with the Russian company CKTI. Special consideration was given to an economical and effective way of manufacturing by using conventional mechanical engineering technologies and common materials. The main objective of this development was to fabricate these casks in countries not having highly specialized industries. Nevertheless, this sandwich cask concept fulfills both the internationally valid IAEA criteria for transportation and the Gennan criteria for long-tenn intennediate storage. The basic cask concept has been designed for adaptation to different spent fuel specifications as well as handling conditions in the NPP. Recently, adaptations have been made for spent fuel from the RBMK and VVER reactors, and also for BWR spent fuel. The analyses of nuclear and thennal behaviour as well as of strength according to IAEA examination requirements (9-m-drop, 1-m-pin drop, 800 °C-fire test) and of the behaviour during accident scenarios at the storage site (drop, fire, gas cloud explosion, side impact) were carried out by means of recognized calculation methods and programmes. In a special experimental programme, the mechanical and thennodynamic properties of heavy concrete were examined and the reference values required for safety analyses were detennined. The results of the safety analysis after drop tests according to IAEA-regulations as well as after 1-m-drops at the storage site were confinned by means of a test programme using a scale model. The fabrication technology has been tested with help of a half scale cask model. The model has been prefabricated in Russia and completed in Gennany. It has been shown that the CONSTOR cask can be fabricated in an effective and economic way.