Operating Experience of High Temperature Sodium Loops for Material Testing

Two independent sodium loops under common name INSOT facilities were constructed in Fast Reactor Technology Group, IGCAR for conducting material testing of PFBR components in dynamic sodium. One loop is utilized for in-sodium Low Cycle Fatigue (LCF) and Creep - Fatigue Interaction (CFI) studies and the second loop for in sodium creep studies. The loop components and piping were constructed using AISI type 316LN/316L material. The sodium loops were constructed by adopting stringent quality control measures stipulated in relevant international codes. Suitable creep and fatigue testing chambers were designed and developed indigenously. The test chambers were qualified for sodium service before commencement of experiments by conducting trial runs. The sodium purity was achieved by on-line purification method prior to admitting into the test chambers and the purity was maintained during testing. Characterization of sodium in the loops during test run were carried out by foil equilibration technique, electro-chemical carbon meter and chemical analysis of sodium sample drawn from the loop using state of art sampling techniques. A versatile PLC based instrumentation system has been successfully implemented for monitoring and controlling the process parameters. Safety interlocks were provided by hardware logic to ensure reliability.