Speaker
Description
At IPR, in Steady State Superconducting Tokamak (SST-1), cryogenic division have two sections, one is 4.2 K and other 77 K temperature that is used for cooling of superconducting magnet material coils and for reduction of heat loads etc. The working at cryogenic temperature and high pressure environment is drastically different than working at room temperature, the material behaviour, its strength, unexpected results. There are various sub-systems of cryogenic helium plant which needs attention and regular inspection with respect to safety concern for working personnel and prevention to the damage of the systems. The cryogenic systems are namely, high pressure at 150 bar (g) in helium gas pressure vessels, safety mountings as safety valve, rupture disc and Non-Return Valve (NRV), LHe and LN2 fluid cryogenic transfer lines, Thermal and vacuum insulation in the system, 80 K vent line, high pressure helium gas cylinders for filling and testing, various low temperature lab experiments as materials testing at 4.2 K and 77 K and high pressure. The kind of problems occurred in systems during operation has been solved efficiently by conducting the performance and validation tests at operating conditions to prevent the repetition of that problem. The average helium leak orders of 10-2 to 10-4 mbar-l/s of identified helium leaks were improved to ≤ 1x10-6 mbar-l/s. In this paper, the hands on experience will be shared of repairing LN2 cryogenic transfer line, replacement of old insulation and vacuum of 80 K cryogenic transfer lines, identification, rectification and mitigation of helium leaks in cryogenic systems, in-house repairing, development of seals, installation and performance tests on safety valves with NRV in the recovery line of high pressure helium gas vessel etc. are the major tasks carried out with safety aspects. This talk also covers the mandatory aspects of cryogen safety, its handling, hazards & its cusses, protection and preventive measures, cryogenic and high pressure safety guidelines and actions at an emergency conditions and lesson learnt in the different sub-systems of cryogenic plant. The implementation of safety measures enhanced the performance of cryo systems without encountered any accident and un-acceptable events.
Keywords: Cryogenics systems, 4.2 K and 77 K temperature, Helium leak tightness, Safety implementation
| Submitters Country | India |
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