Passive Surveillance: A Technique to Characterize the Condition of Power and Control Circuits in a Nuclear Plant

This paper reports on progress by EG&G Idaho in examination of electrical circuits exposed to the accident environment at Three Mile Island Unit 2 (TMI-2) during and after the loss-of-coolant accident of March 28, 1979. Interpretations of the data collected suggest that the major functional impact on the electrical circuits (a) occurs very late in time, (b) is caused by moisture intrusion, and (c) can be detected by remote surveillance prior to functional failure. The electrical testing was performed from outside the TMI-2 Reactor Building at the penetrations using a special circuit characterization and diagnostic system developed by EG&G Idaho. This paper concentrates on representative data from those circuits which were recently retested.