Temperature and hydrogen concentration influence on Zi -2.5Nb alloy mechanical and fracture toughness characteristics

This paper deals with an investigation of temperature and hydrogen concentration influence on Ignalina NPP RBMK-1500 unit 2 reactor fuel channel tube material - Zr-2.5Nb zirconium alloy (TMT-2) mechanical and fracture toughness characteristics. Two types of specimens were used in this study - tensile and compact semi-natural specimens. Testing temperatures were selected from 20 to 300°C that correspond various operating regimes of the reactor. Made-up hydrogen saturated specimens were tested at hydrogen concentration levels from 52 up to 140 ppm m order to examine hydrogen influence on mechanical and fracture toughness characteristics of the alloy. Dependence of fracture toughness to various mechanical characteristics of the alloy was analysed. Investigation has shown correlation of stress intensity factor Kc to modified plasticity criterion of the alloy.