ML20183A431
| ML20183A431 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 07/01/2020 |
| From: | Hay M NRC/RGN-IV/DRP |
| To: | Reasoner C Wolf Creek |
| References | |
| EA-20-089 | |
| Download: ML20183A431 (5) | |
Text
July 1, 2020 EA-20-089 Mr. Cleveland Reasoner III Chief Executive Officer and Chief Nuclear Officer Wolf Creek Nuclear Operating Corporation P.O. Box 411 Burlington, KS 66839
SUBJECT:
NOTICE OF ENFORCEMENT DISCRETION FOR WOLF CREEK NUCLEAR OPERATING CORPORATION [EPID: L-2020-LLD-0000, EA-20-0089]
Dear Mr. Reasoner:
By letter dated June 30, 2020 (ADAMS Accession No. ML20182A429), Wolf Creek Nuclear Operating Corporation (WCNOC, the licensee) requested that the U.S. Nuclear Regulatory Commission (NRC) exercise discretion to not enforce compliance with the actions required in Wolf Creek Generating Station (WCGS) Technical Specifications (TS) related to declaring the train B emergency diesel generator (EDG) inoperable. This letter documented information previously discussed with the NRC during a telephone conference on June 28, 2020, that commenced at 10:00 a.m. (all times discussed in this letter refer to Central Daylight Time). The principal NRC staff members who participated in the telephone conference included: Michael Hay, Acting Director, Division of Reactor Projects, Region IV (RIV); Geoffrey Miller, Deputy Director, Division of Reactor Safety, RIV; Gregory Suber, Deputy Director, Division of Operating Reactor Licensing, Office of Nuclear Reactor Regulation (NRR); Neil OKeefe, Chief, Projects Branch B, RIV; Jennifer Dixon-Herrity, Chief, Plant Licensing Branch 4, NRR; Angela Buford, Chief, Mechanical Engineering and Inservice Testing Branch, NRR; Brian Wittick, Chief, Containment and Plant Systems Branch, NRR; David Loveless, Senior Reactor Analyst, RIV; Michael Montecalvo, Senior Reactor Analyst, Probabilistic Risk Assessment Oversight Branch, NRR; Samson Lee, Project Manager, NRR; Ed Miller, Notice of Enforcement Discretion (NOED)
Program Manager, NRR; Kadijah West, Technical Specification Branch, NRR; Adakou Foli, Electrical Engineering Branch, NRR; Bob Wolfgang, Mechanical Engineering and Inservice Testing Branch, NRR; and Doug Dodson, Senior Resident Inspector, RIV.
On June 25, 2020, at 2:00 p.m., the licensee declared train B EDG inoperable when the fan that was required to provide cooling for the EDG B engine room failed. As a result, the licensee entered TS 3.8.1, AC Sources - Operating, Condition B for one EDG inoperable. The actions included Required Action B.4.1, which requires restoration of the EDG to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. If this action is not met, Required Action H requires the unit be shut down to Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and cooled down to Mode 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. Following declaring EDG B inoperable the licensee verified that a common cause failure of the train A EDG and its cooling fan did not exist by running the EDG and the fan on June 25, 2020, as required by TSs.
C. Reasoner III 2 Electrical testing indicated the failed motor was grounded and needed to be replaced. The licensee determined that the corrective actions necessary to replace and test the supply fan and restore the EDG to operable status could not be completed within the 72-hour Completion Time of Required Action B.4.1 of TS 3.8.1.
During the June 28, 2020, teleconference, the licensee requested the NRC to exercise enforcement discretion for an unanticipated temporary noncompliance with TS 3.8.1 in order to avoid an unnecessary plant transient. The licensee presented the timeline to complete repair and testing of the fan to restore the EDG to operable status, demonstrating that the necessary work and testing could not be completed within the 72-hour Completion Time of Required Action B.4.1 of TS 3.8.1, which would have expired at 2:00 p.m. on June 28, 2020. The Wolf Creek Generating Station Plant Safety Review Committee approved the NOED request on June 28, 2020, prior to the verbal request for an NOED.
The licensee also explained that the longer 7-day allowed outage time in Action B.4.2.1 and B.4.2.2 could not be used because the limitations for invoking this once-per-cycle action were not all met. Specifically, the following required conditions listed in the TS Bases for using Action B.4.2.1 and B.4.2.2 were not met:
- The 7-day allowed outage time may only be used for planned maintenance.
- The diesel generators at Sharpe Station must be verified to be operating properly, including verifying that a load capacity test was completed within the prior eight months.
- Conducive weather condition must exist. The extended EDG completion time only applies between September 7 and April 5.
The licensee requested an additional 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> to restore EDG B to operable status starting at the end of the allowed 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> allowed by Required Action B.4.1. The licensee presented the results of their risk assessment for the proposed period of enforcement discretion. The results were within the limits of normal maintenance risk described in Regulatory Guide 1.160, Monitoring of Maintenance at Nuclear Power Plants. The incremental conditional core damage probability (ICCDP) and incremental conditional large early release probability (ICLERP) quantified were also within the thresholds in NRC Enforcement Manual, Appendix F, Notices of Enforcement Discretion, (ADAMS Accession No. ML19193A023).
Wolf Creek Nuclear Operating Corporation proposed to implement compensatory risk management measures during the proposed period of enforcement discretion that included:
- Supporting the repair and testing work using 24-hour staffing coverage
- Minimizing challenges to offsite power reliability by restricting access to the switchyard and restricting elective maintenance during the period of enforcement discretion
- Raising operator sensitivity to challenges to safety bus power supplies and briefing operators on plant recovery procedures for loss of power events
- Protecting train A safety systems and restricting maintenance and surveillance activities during the period of enforcement discretion
- Deploying FLEX generators if the station experienced a loss of offsite power for greater than 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />
C. Reasoner III 3 The licensee stated that the three station blackout diesel generators and the ten diesel generators at Sharpe Station were available as alternate power sources. The licensee stated that an engineering analysis demonstrated that EDG B could function in an emergency for 7 days without the fan by opening a door allowing outside air into the engine room. The licensee also stated that no severe weather was forecast, which could challenge offsite power availability during the proposed period of enforcement discretion, and grid conditions were normal.
The licensee stated that the sequence of events in responding to the fan failure precluded submitting an emergency TS amendment request. A prior NOED request involving extension of the allowed outage time for EDGs was requested and approved in January 2013, providing an opportunity to have submitted an amendment request to extend the allowed outage time, but the licensee explained that priority had been given to capital improvement projects and efforts to improve plant performance. However, the licensee committed to submit a license amendment request to extend the allowed outage time following approval of their NOED request, describing two options under consideration to meet this outcome.
In response to the licensees request and presentation, the NRC concluded that compliance with the TS 3.8.1, Action B.4.1, would cause an unnecessary transient without a corresponding benefit in public health and safety. NRC risk analysts independently verified that continued operation of the plant during the period of enforcement discretion would not cause risk to exceed the level of risk determined to be acceptable during normal work controls and, therefore, there would be no net increase in radiological risk to the public. The NRC staff concluded that the licensees June 30, 2020, letter was consistent with the verbal NOED request from the June 28, 2020, teleconference.
The staff noted that the timeline for restoring EDG B provided by the licensee did not support the need for a 36-hour extension as initially requested during the teleconference. After a discussion of uncertainties in the repair plan, the licensee agreed that an extension of 22 hours2.546296e-4 days <br />0.00611 hours <br />3.637566e-5 weeks <br />8.371e-6 months <br /> was appropriate prior to the conclusion of the call.
Based on the NRC staffs evaluation of the licensees request, the staff determined that granting this NOED is consistent with the NRCs Enforcement Policy and staff guidance, and would have no adverse impact on public health and safety to avoid an unnecessary plant transient as per the criteria in Section 2.5 of Appendix F, Notices of Enforcement Discretion, of the NRCs Enforcement Manual. Therefore, as communicated to your staff at 12:40 p.m. on June 28, 2020, the NRC exercised discretion to not enforce compliance with Technical Specification LCO 3.8.1 Required Actions B.4.1 for a total period of 94 hours0.00109 days <br />0.0261 hours <br />1.554233e-4 weeks <br />3.5767e-5 months <br />, to expire at 12:00 p.m. on June 29, 2020.
The staff noted that the licensee was able to complete repairs and testing, and EDG B was declared operable at 4:25 a.m. on July 29, 2020, within the period of enforcement discretion.
C. Reasoner III 4 As stated in the Enforcement Policy, action will be taken, to the extent that violations were involved, for the root cause that led to the noncompliance for which this NOED was necessary.
Sincerely,
/RA/
Michael C. Hay, Acting Director Division of Reactor Projects Docket No. 05000482 License No. NPF-42
Enclosure:
As stated cc w/ encl: Distribution via LISTSERV
ML20183A431 Non-Sensitive Publicly Available SUNSI Review Sensitive Non-Publicly Available OFFICE BC:DRP/B DD: DRS DD: DORL/NRR D: DRP NAME N. OKeefe G. Miller G. Suber M. Hay DATE 07/01/2020 07/01/2020 07/01/2020 07/01/2020