Technical Specification (TS) 3.3.6.1,
Primary Containment Isolation Instrumentation, requires that the
RWCU high
differential flow instrumentation be
operable in modes 1, 2, or 3. If the instrumentation is not
operable, then
TS 3.3.6.1 requires that the
RWCU penetration flow path be isolated within
1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. Contrary to the above, the licensee identified that the
RWCU high
differential flow instrumentation was not
operable and the
penetration flow path was not isolated when the unit entered mode 1 on April 16, 2011 until August 2, 2011, because the
RWCU inlet flow sensing element was installed backwards, causing the flow sensing element to be inaccurate. The resulting inaccuracy caused the instrumentation to be unable to isolate within the required TS limit of less than or equal to 73 gallons per minute
differential flow. The finding was determined to be of very low safety significance per
Appendix A of Inspection Manual Chapter 0609,
Significance Determination Process, because the finding: 1) did not only represent a degradation of the radiological barrier function provided for the control room, auxiliary building, spent fuel pool, or the
standby gas treatment system, 2) did not represent a degradation of the barrier function of the control room against smoke or a toxic atmosphere, and 3) did not represent an actual open pathway in the physical integrity of reactor containment. Upon discovery of the condition, the licensee isolated the affected
penetration flow path and installed the flow sensing element correctly. The issue is in the licensees
CAP as
NCR #479248.
