Different fracture safety philosophies: Do they impair the type B(U) concept

Type B packages are required to be safe against brittle fracture. Different methods to demonstrate this resistance are possible and are practised worldwide. In the case of new material nodular cast iron, it has been found that the different intepretations of this basic requirement can lead to difficulties in the validation of Type B(U) certificates. The method applied in the Federal Republic of Germany is based mainly on tests using full-scale prototypes, while in the United States of America the method used so far is an adaptation of pressure vessel procedures, or a combination of the two approaches. The justifications for these interpretations are discussed. It is proposed that the Type B(U) concept, a major IAEA principle, should be followed in order to avoid a duplication of the complete licensing procedure. This can be achieved by promoting a greater degree of confidence between competent authorities, especially those of highly industrialized countries. (author)