To enhance the safety case for the superheater header penetrations at Wylfa Nuclear Power Station, WS Atkins Consultants Ltd. undertook the design of safety restraints to limit the possible consequences of failure of their closure welds. The restraints contain mild steel tubes to be crushed diametrically as the energy absorbing components. The crush tubes were designed using LS-DYNA, a non-linear finite element code. Component testing was undertaken to validate the crush tube finite element models. The results were incorporated into system models of the restraints, also developed using LS-DYNA. These models were used to design the restraint and assess the integrity of the superheater header penetrations. A full restraint assembly was tested under impact loading by a specially designed rig, which showed the restraint behaviour to be acceptable under loading significantly in excess of the design conditions. This paper describes the development of the finite element models, compares results from the analytical work and the tests and summarizes the lessons learned for future analysis.
展开▼
