ML14330A485
| ML14330A485 | |
| Person / Time | |
|---|---|
| Site: | Wolf Creek  |
| Issue date: | 11/26/2014 |
| From: | Troy Pruett NRC Region 4 |
| To: | Heflin A Wolf Creek |
| O'Keefe N | |
| References | |
| EA-12-135 | |
| Download: ML14330A485 (5) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION REGION IV 1600 E LAMAR BLVD ARLINGTON, TX 7601-4511 November 26, 2014 EA-12-135 Adam C. Heflin, President and Chief Executive Officer Wolf Creek Nuclear Operating Corporation P.O. Box 411 Burlington, KS 66839
SUBJECT:
WOLF CREEK GENERATING STATION - PLANNED ACTIONS TO RESTORE COMPLIANCE REGARDING ESSENTIAL SERVICE WATER DESIGN ISSUES
Dear Mr. Heflin:
On October 2, 2014, a public meeting was held between the U.S. Nuclear Regulatory Commission (NRC) Region IV staff and members of the Wolf Creek Nuclear Operating Corporation (WCNOC) staff to discuss your plans to address design issues associated with the essential service water (ESW) system. A summary of this public meeting is available in the Agencywide Documents Access and Management System (ADAMS) (Accession No. ML14290A257). The NRC has issued a number of violations associated with pitting corrosion in ESW piping and the containment coolers, as well as significant pressure transients (commonly referred to as water hammer events). A summary of the inspection findings associated with these issues and your responses to the associated violations is enclosed.
NRC Inspection Report 05000482-2014007 (ADAMS ML14283A612) documented that you have made significant progress in replacing degraded ESW piping, but have not yet implemented final actions to mitigate the effects of water hammer or to address degraded containment coolers. Our continuing inspection of your ESW piping replacement indicated that the replacements have been prioritized based on safety, and are firmly scheduled and funded.
However, corrective action and restoration of compliance for the containment coolers and water hammer mitigation have not been timely, and commitments for completing corrective actions have been repeatedly extended. Our continuing inspections have allowed us to conclude that a safety concern does not exist because you have replaced the most risk-significant degraded piping, improved non-destructive examinations to monitor the condition of the remaining piping, your pressure testing of the containment coolers have been sufficient to demonstrate continued operability and provide a reasonable assurance that the system will withstand water hammer events.
A. Heflin During the discussions held during the October 2, 2014 meeting, your staff summarized the technical issues and your plans to correct the design deficiencies associated with the ESW system and restore compliance with NRC requirements. Your staff indicated that there was some uncertainty in the schedule for implementing corrective actions, but the plan called for implementing plant modifications during the next refueling outage.
In order to facilitate NRC inspection planning to verify that your long-term actions have restored the system design and restored compliance with NRC requirements, you are requested to respond within 30 days of the date of this letter to provide the following information:
- 1. The date when the design change documents and modification packages will be complete and available for inspection for the containment cooler replacement and water hammer mitigation modification.
- 2. The dates when post-modification testing for these modifications is expected to occur.
- 3. The dates when full compliance will be restored for the significant conditions adverse to quality associated with ESW system piping pitting corrosion, containment cooler pitting corrosion, and ESW system water hammer.
In accordance with 10 CFR 2.390 of the NRCs Rules of Practice, a copy of this letter, its enclosure, and your response will be made available electronically for public inspection in the NRC Public Document Room or from the NRCs document system (ADAMS), accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html.
Sincerely,
/RA/
Troy W. Pruett Director, Division of Reactor Projects NRC Regional IV Docket No.: 50-482 License No.: NPF-42
Enclosure:
Summary of ESW Design Issues Distribution: See next page
SUBJECT:
WOLF CREEK GENERATING STATION - PLANNED ACTIONS TO RESTORE COMPLIANCE REGARDING ESSENTIAL SERVICE WATER DESIGN ISSUES DISTRIBUTION:
Regional Administrator (Marc.Dapas@nrc.gov)
Deputy Regional Administrator (Kriss.Kennedy@nrc.gov)
Acting DRP Director (Troy.Pruett@nrc.gov)
Acting DRP Deputy Director (Jason.Kozal@nrc.gov)
DRS Director (Anton.Vegel@nrc.gov)
DRS Deputy Director (Jeff.Clark@nrc.gov)
Senior Resident Inspector (Charles.Peabody@nrc.gov)
Resident Inspector (Raja.Stroble@nrc.gov)
WC Administrative Assistant (Carey.Spoon@nrc.gov)
Branch Chief, DRP/B (Neil.OKeefe@nrc.gov)
Senior Project Engineer, DRP/B (David.Proulx@nrc.gov)
Project Engineer, DRP/B (Fabian.Thomas@nrc.gov)
Branch Chief, DRS/EB1 (Tom.Farnholtz@nrc.gov)
Public Affairs Officer (Victor.Dricks@nrc.gov)
Public Affairs Officer (Lara.Uselding@nrc.gov)
Project Manager (Fred.Lyon@nrc.gov)
Branch Chief, DRS/TSB (Geoffrey.Miller@nrc.gov)
RITS Coordinator (Marisa.Herrera@nrc.gov)
ACES (R4Enforcement.Resource@nrc.gov)
OE (RIDSOEmailcenter.resource@nrc.gov)
Regional Counsel (Karla.Fuller@nrc.gov)
Technical Support Assistant (Loretta.Williams@nrc.gov)
Congressional Affairs Officer (Jenny.Weil@nrc.gov)
RIV Congressional Affairs Officer (Angel.Moreno@nrc.gov)
RIV/ETA: OEDO (Cayetano.Santos@nrc.gov)
Distribution via Listserv for Wolf Creek Generating Station ADAMS ACCESSION NUMBER ML14330A485 SUNSI Review ADAMS Publicly Available Non-Sensitive By: NFO Yes N Non-Publicly Available S e ns itive OFFICE BC:DRP/B D:DRS D:DRP NAME NOKeefe/dll AVegel TPruett SIGNATURE /RA/ /RA/ /RA/
DATE 11/19/14 11/19/14 11/22/14
SUMMARY
OF ESW DESIGN ISSUES
Background
The Wolf Creek essential service water (ESW) system has a design deficiency which creates conditions that result in water hammer as a result of column separation during loss of offsite power events to one or more safety trains. Column separation occurs when the running service water pump suddenly stops, since water attempts to drain from the system into the lake until an ESW pump can be automatically started. The rapid refiling of the pipe and collapsing of voids that formed during the draining cause a large pressure spike in each train of ESW.
The water hammer events have resulted in large pressure transients that challenged ESW system components.
Concurrent with the susceptibility to water hammer, the ESW system has experienced pitting corrosion in carbon steel piping and copper-nickel heat exchanger tubes, which has reduced the ability of the material to withstand water hammer events. The plant has experienced water hammer events that caused leaks in the containment cooler tubes and system piping and other fittings as a result of these conditions.
Enforcement The NRC has issued several enforcement actions in response to these failures.
In 2009, the NRC issued non-cited violation (NCV)05000482/2009007-03 (ADAMS ML100330574), for failure to perform a proper condition report screening and subsequent root cause analysis and evaluation of the combined effects of water hammer and internal corrosion in the ESW system. Loss of offsite power events in April 2008 and August 2009, and subsequent starting of the ESW system resulted in water hammer events and system leaks.
Additional water hammer events in 1993, 1995, 1999, and 2004 had resulted in ESW system damage. Also in 2009, ESW system pitting had resulted in other ESW system leaks.
In 2010, the NRC issued Notice of Violation 05000482/2010006-05 (ADAMS ML102560258) for failure to correct a significant condition adverse to quality, in that the licensee had failed to determine the root cause and provide corrective actions to prevent recurrence for water hammer events that resulted in leaks in the containment coolers.
In a letter dated October 11, 2010, (ADAMS ML102920162) responding to Notice of Violation 05000482/2010006-05, WCNOC focused on the corrective action program elements that led to the failure to properly evaluate the conditions, but did not propose specific corrective actions address the significant condition adverse to quality in the plant.
In 2012, the NRC issued Notice of Violation (NOV)05000482/2012007-03 (ADAMS ML12191A269) for the failure to determine the cause of a significant condition adverse to quality and prevent repetition for the ESW water hammer event on August 19, 2009, resulting in a system leak. There was a repeat occurrence on January 13, 2012, when a water hammer event resulted in ESW leak inside containment.
Enclosure
In a letter dated August 2, 2012, (ADAMS ML12222A007) responding to Notice of Violation 05000482/2012007-03, WCNOC committed to mitigate the adverse effects of water hammer in the essential service water system by April 2, 2014. This letter also indicated that improved corrosion monitoring would be implemented by December 15, 2012. This was later revised in a letter dated December 13, 2012, (ADAMS ML12363A116) to state that ESW piping replacement was planned, but a scope and completing schedule for the piping replacement was not provided.
In a letter dated June 27, 2013, (ADAMS ML13190A036) WCNOC revised the previous commitments stated in the August 2, 2012, letter to be completed by May 2014, and committed to replace the remaining above-ground essential service water system in the next five refueling outages.
In a letter dated May 8, 2014, (ADAMS ML14321A625) WCNOC again extended the completion date of the corrective actions to mitigate ESW system water hammer effects to March 7, 2015, because the planned modification was found to have significant deficiencies shortly before planned implementation In a separate letter dated May 8, 2014, (ADAMS ML14139A009) WCNOC committed to replace, inspect or test the containment cooler bundles prior to starting up from the Spring 2015 refueling outage.
In September, 2014, the NRC issued NCV 05000482/2014007-03, (ADAMS ML14283A612) for failure to include the containment coolers in the test program. In addition, NRC Inspection Report 05000482/2014007 discussed that NOV 05000482/2012007-003 was reviewed but not closed, because WCNOC had failed to restore compliance.
Enclosure