Pre-assembly tests of 80 K booster systems cryostats and VJ lines

The Steady State Superconducting Tokamak (SST-1) machine is equipped with liquid nitrogen (LN2) cooled bubble panel type thermal shield to minimize the steady state heat loads on the superconducting magnet system at 4.5 K from ambient. The 80 K Booster system is essential for single phase LN2 flow inside bubble panels for uniform temperature distribution within (80K - 85K). Design, analysis and manufacturing of the 80 K booster system were done by the M/s Cryozone. Booster system is in form of three storey building as pump cryostat at bottom, sub-cooler vessel cryostat at middle and pressurized vessel cryostat at upper. Flexible bellows type process interface provided between the cryostats. After factory acceptance test (FAT) at vendor site, the 80 K booster system has been delivered to IPR site in disassemble form with each cryostats in different box package. Before carrying out installation, commissioning and testing of booster system at IPR site, it is envisaged to have possible pre-assembly tests of each cryostats and VJ lines as there may be any chance of non-conformity issues viz. damage during transportation. In order to validate the same before actual assembly at IPR site, several tests have been carried out viz. helium leak tightness of the cryostats, NER test, high pressure holding test at ambient as well as at liquid nitrogen conditions. This paper describes the procedures and test results at individual component level of the 80 K booster system in prior to their final integrated installation. (author)