Doel 3 - Tihange 2 / German RSK Evaluation & Reply

OI 4

With regard to the load-bearing capacity analysis according to ASME III, NB-3228.3 for RPV sections containing flaws, additional fracture mechanics analyses were conducted by the Belgian side for 1.5 times the design pressure. Thus, it could be demonstrated that at 1.5 times the design pressure there are sufficient margins with regard to a global plastic collapse. In addition, a representative accumulation of flakes has been modelled in 3D in an elasto-plastic finite element analysis and it was demonstrated that also the local plastic strains remain limited below 1.5 times the design pressure and no plastic ligaments will develop between the individual cracks. Accordingly, no local plastic failure will occur. Position of the RSK: The Belgian side has responded to the question of the RSK with the new analyses. The approach is comprehensible. It was thus confirmed that the requirements of the ASME code for the load- bearing capacity analysis are met and that there is a safety factor of 1.5 with regard to the plastic collapse load. This issue has thus been clarified.

•

Subsequent to the meeting, FANC confirmed that the Belgian institutions will become involved in German research projects. How this will be organised in practice, is still to be agreed upon.

RSK/ESK Secretariat at the Federal Office for the Safety of Nuclear Waste Management

Page 14 of 19