At 0833 [EDT] on May 3, 2016, security received an alarm on a Main Control Room (
MCR) door. At 0847 [EDT], security notified the
MCR staff of the door alarm and that the door was incapable of closure. At this time, both control room ventilation filtration trains (
CREVS) were declared
inoperable in accordance with
Technical Specification 3.7.10, Condition B, due to the inoperability of the
Control Room Envelope (
CRE). Attempts to close the door were made, and it was identified that a screw had become wedged at the base of the door preventing it from latching. At 0855 [EDT], the screw was removed and the door verified to close as designed.
CREVS was determined to be
operable and
LCO 3.7.10, Condition B was exited.
The safety function of the CRE boundary is to ensure the in-leakage of unfiltered air into the CRE will not exceed the in-leakage assumed in the licensing basis analysis of Design Basis Accident (DBA) consequences to CRE occupants. In addition to an intact CRE boundary maintaining CRE occupant dose from a large radioactive release below the calculated dose in the licensing basis consequence analysis for DBAs, it also ensures the occupants are protected from hazardous chemicals and smoke.
This condition had no impact to the health and safety of the public.
The NRC Resident Inspector has been notified.
