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A finding of very low safety significance … A finding of very low safety significance and associated NCV of10 CFR Part 50, Appendix B, Criterion III, Design Control, was self-revealed upon discovery of the use of a non-conservative setpoint for the Low Temperature Overpressure Protection (LTOP) systems for Units 1 and 2. Specifically, licensee calculation 2000-0001, RCS (Reactor Coolant System) Pressure and Temperature Limits and Low Temperature Overpressure Protection Setpoints Applicable through32.2 EFPY Unit 1 and 34.0 EFPY Unit 2, established an LTOP setpoint of500 pounds per square inch gauge (psig). However, by using the setpoint calculation methodology of 10 CFR Part 50, Appendix G, the resulting LTOP setpoint was calculated to be 420 psig. Therefore, the 500 psig setpoint was found to be non-conservative and the LTOP systems were declared inoperable. As part of its corrective actions, the licensee revised the LTOP setpoints from 500 psig to 420 psig and made changes to operating procedures to delineate the acceptable operating conditions of the reactor coolant pumps and charging pumps during low temperature conditions. The finding was determined to be more than minor because the finding was associated with the human performance attribute of the Barrier Integrity Cornerstone and affected the cornerstone objective of providing reasonable assurance that physical design barriers, such as containment, protect the public from radionuclide releases caused by accidents or events. Specifically, the non-conservative LTOP setpoint provided reasonable doubt that the integrity of the RCS pressure boundary would be maintained during low temperature conditions. The inspectors determined the finding could be evaluated using the SDP in accordance with IMC 0609, Significance Determination Process, Attachment 0609.04, Phase 1 - Initial Screening and Characterization of Findings, Table 4a for the Barrier Integrity Cornerstone, dated January 10, 2008.The inspectors determined that the finding was of very low safety significance (Green)because all of the questions in the containment barrier column of Table 4a were answered NO and the actual setpoint of the power operated relief valves was 415 psig, below the revised LTOP setpoint. The inspectors also determined that the finding has across-cutting aspect in the area of problem identification and resolution, corrective action program component, because personnel did not use a low threshold for identifying issues P.1(a). (Section 4OA3.1identifying issues P.1(a). (Section 4OA3.1
23:59:59, 31 December 2008 +
23:59:59, 31 December 2008 +
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00:36:19, 21 February 2018 +
23:59:59, 31 December 2008 +