Open Phase Condition

Byron Open Phase condition pertains to an nuclear industry issue regarding a design vulnerability in the 4.16kV bus undervoltage protection scheme in that an Open Phase Condition (OPC) resulting in unbalanced three-phase currents (which can damage plant equipment) went undetected. Byron initiated ENS 47636. INPO generated Level 2 IER L2-12-14 and NRC generated IN 2012-03 and then Bulletin 2012-01. Issue is currently tracked as NEI Open Phase Condition (OPC) Initiative.

Byron Open Phase Condition (OPC) Issue An automatic Reactor SCRAM at Byron station resulted from a design vulnerability in the 4.16 kV bus undervoltage protection scheme in that an Open Phase Condition (OPC) resulting in unbalanced three-phase currents (which can and did damage plant equipment) went undetected.