Experiences and Status in Safety Assessment Methods within the Scope of Licensing Procedures for Multi-Purpose Flasks in Germany

Abstract

The Federal Institute for Materials Research and Testing in Germany (BAM) is the German competent authority for safety assessment and design testing of flasks for transport and storage of radioactive waste. Referring to the IAEA regulations (Safety Standards Series No ST-1) four different methods for demonstration of compliance with the performance standards are possible: (1) tests with prototype flasks, (2) tests with scaled models, (3) reference to previous safety demonstrations, and (4) calculation. The advantages and disadvantages of these methods. are described with reference to the nearly 20 years experience of BAM in design testing under mechanical accident conditions. Drop testing with prototype flasks and scaled model flasks was the basic method at the beginning of flask development. With better knowledge of flask behaviour under such impact conditions methods (3) and (4) were increasingly used for various flask designs. The present trend is to use numerical calculation methods also for new flask designs because of the high potential of modem computer technology. Some actual examples are given and the necessary requirements for the acceptance of this method are discussed. During recent years numerous flask designs were granted transport licences as well as licences for interim storage at the Gorleben and Ahaus sites. Because of different actions of opponents the licenses for the interim storage sites were the object of legal proceedings with special reference to the flask design testing methods. Finally, the experience obtained from these legal disputes and their relevance to acceptable safety assessment methods are discussed.