A review of industry operating experience (
NRC Event Number 49889) regarding the impact of unfused Direct Current (
DC) circuits has determined the described condition to be applicable to Millstone Power Station Unit 2 (MPS2) resulting in an
unanalyzed condition with respect to
10 CFR 50 Appendix R analysis requirements.
In the postulated event, a fire induced hot short could adversely impact safe shutdown equipment. The MPS2 Main Turbine Emergency Lube Oil pump control and indication circuits route to the main control room. It is postulated that a fire in one fire area can damage this cable and cause short circuits without protection that would overheat the cable and possibly result in secondary fires in other fire areas where the cables are routed. The secondary fire could adversely affect safe shutdown equipment and potentially cause the loss of the ability to conduct a safe shutdown as required by 10 CFR 50 Appendix R.
Interim compensatory measures (i.e., fire watches) have been implemented for affected areas of the plant.
This condition is being reported pursuant to 10 CFR 50.72(b)(3)(ii)(B).
The NRC Resident Inspector has been notified.
The licensee notified the State of
Connecticut and the town of Waterford.
