UNEXPECTED ANOMALY OF GHF (GRADIENT HEATING FURNACE) ON BOARD

摘要

GHF (Gradient Heating Furnace) is vacuum furnace thatrnenables to raise temperature up to 1600 degree Celsius.rnGHF consumes large amount of power (about 4 kW),rncontains pressure vessel and has interface with vacuumrnline. Therefore, GHF has hazardous function in nature.rnJAXA performed safety analysis thoroughly, identifiedrnall causes and set appropriate safety controls to meetrnsafety requirements. JAXA launched GHF in Januaryrnof 2011 and operates in Kibo laboratory of ISSrn(International Space Station). JAXA encounteredrnunexpected anomalies during operations on-board.rnThey did not give safety degradation actually sincernsafety devices inherent to GHF worked, but some ofrnanomalies were unexpected.rnThis paper presents one of the "unexpected" anomalyrnhappened on-board, and how it relates with safety andrnhow it is controlled not to lead to safety accident.rnIt is pretty hard to find out “root cause” for some ofrnanomalies due to limited telemetry information and crewrnresources. In addition, most of engineers designingrnGHF have gone. This paper also introduces agencyrnlevel efforts to struggle to find out causes and to setrnappropriate countermeasure.rnFinally, this paper summaries lessons and learned fromrnanomaly JAXA encountered.