A finding of very low safety-significance (Green) and associated Non-Cited Violation of
10 CFR Part 50, Appendix B, Criterion III, Design Control was identified by the inspectors for the licensees failure to adequately calculate the maximum room temperature for G-01 and G-02. Specifically, the licensees calculation 2005-0054 failed to incorporate the design basis described in Technical Specification (TS) bases 3.8.1 related to the numbers of fire
dampers associated with G-01 and G-02 exhaust fans that must be opened to maintain room temperature. The calculation also failed to demonstrate that the temperature stratification close to the combustion air intake filter was acceptable. Instead, the calculation only considered the bulk air temperature in the room. The licensee subsequently entered these concerns into their corrective action program as
AR 01162599 and
AR 01162759. The finding was determined to be more than minor because the finding was similar to
IMC 0612, Appendix E, Example (3.J). The calculation errors were significant in that there was reasonable doubt that the maximum room temperature would not exceed the value of the Vendor Technical manual. The finding impacted the Mitigating System cornerstone of ensuring the availability, reliability, and capability of systems that respond to
initiating events to prevent undesirable consequences. Specifically, the licensee did not ensure that the maximum room temperature of EDG-1 and EDG-2 would not exceed 115 degrees (o) Fahrenheit (F), which is required to be maintained to ensure that the
EDGs will perform their safety function during a design basis accident when the outside air temperature was 95o F. The finding was of very low safety-significance based on a Phase 1 screening in accordance with
IMC 0609, Appendix A, Significance Determination of Reactor Inspection Findings for At-Power Situations. This finding was not associated with a cross-cutting aspect because the finding was not indicative of the licensees current performance
