TS 3.4.10, Pressurizer Safety Valves, requires two pressurizer safety valves to be
operable during Modes 1 and 2, and in Mode 3 when all
RCS cold leg temperatures are greater than 365F for Unit 1 or 301F for Unit 2. With one pressurizer safety valve
inoperable,
TS 3.4.10, Condition A, requires the
inoperable valve to be restored within 15 minutes. If this is not able to be completed or if two pressurizer safety valves are
inoperable, then
TS 3.4.10, Condition B, is entered which requires the unit to be in Mode 3 within
6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> AND the unit to be cooled down to below 365F for Unit 1 or 301F for Unit 2 within
12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Contrary to the above, on March 12, 2013, Unit 2 pressurizer safety valve BNO4375, which had been installed in position 2RV200 during the previous operating cycle, was measured higher than its TS allowable value during as-found lift point testing. On February 28, 2014, Unit 1 pressurizer safety valves BN04373 and BM07952, which had been installed in positions 1RV200 and 1RV201 respectively during the previous operating cycle, were measured lower than their TS allowable value during as-found lift point testing. In both cases, the valves had been replaced with tested,
operable valves prior to discovery of the as-found condition. Exelon concluded that the valve had been
inoperable for a period of time greater than the allowed TS outage times specified in
TS 3.4.10. Exelon entered both issues into their
CAP as CR-2013-002415, CR- 2014-002236, and CR-2014-002237. In accordance with
IMC 0609.04, Initial Characterization of Findings, and
IMC 0609, Appendix A, The
Significance Determination Process for Findings at Power, Exhibit 2,
Mitigating Systems Screening Questions, the inspectors determined that each example was a finding of very low safety significance (Green) because the finding did not represent an actual loss of the pressurizer safety valve systems credited safety function to relieve pressure to prevent
RCS pressure from exceeding 110 percent of
RCS pipings design pressure.
