IR 05000482/2012008
| ML12095A414 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 04/04/2012 |
| From: | Collins E Region 4 Administrator |
| To: | Matthew Sunseri Wolf Creek |
| References | |
| IR-12-008 | |
| Download: ML12095A414 (58) | |
Text
April 4, 2012
SUBJECT:
WOLF CREEK NUCLEAR OPERATING CORPORATION - NRC AUGMENTED INSPECTION TEAM REPORT 05000482/2012008
Dear Mr. Sunseri:
On March 6, 2012, the U. S. Nuclear Regulatory Commission (NRC) completed an inspection at your Wolf Creek Generating Station. The enclosed report documents the inspection results, which were discussed with you and other members of your staff during a public exit meeting on March 6, 2012.
On January 13, 2012, Wolf Creek Generating Station declared a Notification of Unusual Event (NOUE) at 2:15 p.m. following an automatic reactor trip and loss of offsite power. The loss of offsite power was the result of two separate electrical failures: the failure of a main generator output breaker, followed by an unexpected loss of power to the startup transformer, which together caused the switchyard to be deenergized. All safety systems initially responded as expected, and emergency diesel generators automatically powered safety-related equipment.
Wolf Creek terminated the NOUE after offsite power was restored to safety-related buses approximately 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> into the event, and the plant was cooled down. The licensee restored power to most of the plant systems on January 17 after verifying that the non-vital switchboards were safe to energize. There were no radiological releases due to this event.
In accordance with Management Directive 8.3, NRC Incident Investigation Program, deterministic and conditional risk criteria were used to evaluate the level of NRC response for this operational event. Because two deterministic criteria were met (multiple failures in systems used to mitigate the event, and repetitive failures or events involving safety-related systems),
and the conditional core damage probability for the event was estimated to be in the overlap range for a special inspection/augmented inspection, Region IV concluded that the NRC response should be an augmented inspection team.
Based on inspection, the team concluded that: (1) your operators responded to the event in a manner that protected public health and safety; (2) safety system functions were maintained; and (3) equipment issues, some of which you had knowledge of but hadnt corrected before this event, complicated the response to this event. The purpose of this inspection was to gather facts and identify issues requiring follow-up, and, as such, no findings were identified. Items requiring additional follow-up are documented as unresolved items in the enclosed report. NRC
UNITED STATES NUCLEAR REGULATORY COMMISSION
REGION IV
1600 EAST LAMAR BLVD ARLINGTON, TEXAS 76011-4511 inspectors have verified that those equipment issues required to be resolved before plant startup were adequately resolved.
In accordance with 10 CFR 2.390 of the NRCs Rules of Practice, a copy of this letter, its enclosure, and your response (if any) will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records (PARS) component of the NRCs document system (ADAMS). ADAMS is accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).
Sincerely,
/RA/
Elmo E. Collins Regional Administrator
Docket No.: 05000482 License No: NPF-42
Enclosure: Inspection Report 05000482/2012008
w/ Attachments:
1. Supplemental Information 2. Sequence of Events 3. Augmented Inspection Team Charter
cc w/ encl: Electronic Distribution