At [2258]
CST, on January 5, 2016, with the plant operating at 100 percent power, the main control room alarm indicating high pressure in the auxiliary building actuated. Operators confirmed that the building pressure, corrected for temperature, indicated slightly positive, whereas the building pressure limit in Technical Specifications is 0.0 - 3.0 inches of water negative pressure.
Secondary containment was declared inoperable, and the Division 2 standby gas system was started. This action restored building pressure to the acceptable range, and the building was declared operable at [0027 CST] on January 6.
This condition is being reported in accordance with
10 CFR 50.72(b)(3)(v)(C) as an event that caused the
secondary containment to be potentially incapable of performing its safety function. The NRC Senior Resident Inspector was notified.
