Ultrasonic Study of Defects in Ductile Cast Iron Inserts for Spent Nuclear Fuel Disposal

Safe containment of radionuclides from spent nuclear fuel in geological disposal for hundred thousands of years, which may cover the period of glaciation, requires analysis of material behaviour of fuel containers under ice-age loads. The primary approach to prevent container failure is to determine critical defects and the elimination of such manufacturing defects identified by means of non-destructive examination. The results of the immersion ultrasonic techniques over a range of frequencies from 1 to 5 MHz, which was used to identify microstructure defects in a section of a real container made of ductile cast iron within the Swedish KBS 3, are reviewed. The ability of the method to detect slag inclusions and cracks is examined and the limitations of the technique in the case the large components with complex geometry are discussed.JRC.F.4-Nuclear design safet