On February 6, 2017, the licensee identified during an engineering review that a vendor recommendation for containment air cooler (
CAC) motors was not incorporated into plant procedures. The
CAC fan motor vendor manual (M40000002) states that the motors were designed and manufactured to meet the requirements of National Electrical Manufacturers Association (
NEMA) standard MG1 for motors and generators which recommends no more than two cold starts and one hot start per hour. The
CAC monthly surveillance test procedures [DBSP03294 (
CAC 1 Monthly Test), DBSP03295 (
CAC 2 Monthly Test), and DBSP03296 (
CAC 3 Monthly Test)] did not specify 31 limitations on the number of allowable hot and cold starts per hour. As a result, the motors were routinely operated with more than one hot start per hour, and the inspectors concluded it contributed to the failure of the
CAC 1 fan motor in May 2014 as discussed in section 4OA2.3.
10 CFR Part 50, Appendix B, Criterion V Instructions, Procedures, and Drawings states: Activities affecting quality shall be prescribed by documented instructions, procedures, or drawings, of a type appropriate to the circumstances and shall be accomplished in accordance with these instructions, procedures, or drawings. Instructions, procedures, or drawings shall include appropriate quantitative or qualitative acceptance criteria for determining that important activities have been satisfactorily accomplished. Contrary to these requirements, the licensee failed to incorporate appropriate vendor recommendations on the number of hot and cold starts allowed per hour for the
CAC fan motors into the
CAC monthly surveillance procedures and was at least a contributor to the failure of
CAC 1 in May 2014. The licensee had operated these motors in this manner for several years prior to the failure of
CAC 1 motor. The objective of the Mitigating System Cornerstone of Reactor Safety is to ensure the availability, reliability, and capability of systems that respond to
initiating events to prevent undesirable consequences (i.e., core damage). A key attribute of this objective involves maintaining procedure quality of maintenance and testing procedures. In accordance with NRC
Inspection Manual Chapter (IMC) 0612, Power Reactor Inspection Reports, Appendix B, Issue Screening, the inspectors determined that the violation was of more than minor significance in that it had a direct impact on this cornerstone objective. Specifically, the failure to have incorporated into station procedures the limit and precaution that
CAC motors should be limited to two cold starts and one hot start per hour resulted in routinely cycling the containment air coolers with more than one hot start per hour, and ultimately was a contributor to the failure of
CAC 1 motor in May 2014. Using NRC
IMC 0609, Appendix A, The
Significance Determination Process for Findings At-Power, Exhibit 2, Mitigating System Screening Questions, the inspectors determined that the violation was of very low safety significance (Green), since the inspectors answered no to all of the screening questions. The licensee had entered this issue into their
CAP as CR 201701306. Licensee corrective actions included, but were not limited to, updating the
CAC monthly surveillance procedures to add a new limit and precaution on allowable
CAC motor starts per hour.
