A Case Diagnose of Loose Part for MCP Blade in TNPS Unit 1

An alarm event of loose part monitored by LPMS of unit 1 in TNPS was analyzed and diagnosed using the off line-analysis software of LPMS.The diagnosis conclusion was made that the events lied in or near by the main pump of loop 4 and the event was not a loosed part but may was a loosing part or dynamic to static friction.According to the overhaul suggestion,an inspect to the main pump of loop 4 and an explore to the bottom of pressure vessel were putted in practice in the time of T101 overhaul for unit 1,and it was found that a lamina of the impeller of the main pump of loop 4 was broken off and the lamina was found on the bottom of the pressure vessel.So the diagnosis was proved correctly.It shows that the effective moni-toring and the professional diagnosis to loose part play an important role in overhaul of nuclear power plant.