IR 05000390/2006010
| ML061780615 | |
| Person / Time | |
|---|---|
| Site: | Watts Bar  |
| Issue date: | 06/27/2006 |
| From: | Widmann M Reactor Projects Region 2 Branch 6 |
| To: | Singer K Tennessee Valley Authority |
| References | |
| IR-06-010 | |
| Download: ML061780615 (15) | |
Text
June 27, 2006
SUBJECT:
WATTS BAR NUCLEAR PLANT - NRC SUPPLEMENTAL INSPECTION REPORT NO. 05000390/2006010
Dear Mr. Singer:
our Final Significance Determination Letter dated April 7, 2006, that
, with Mr. J. Laughlin and other members of your staff.
This supplemental inspection was an examination of the root cause analysis, extent of cause and extent of condition determinations, and corrective actions associated with the White finding identified in the Barrier Integrity Cornerstone. The finding was related to the failure to implement shutdown procedures which resulted in multiple actuations of pressurizer PORVs on February 22, 2005.
Based on this inspection, we have concluded that your root cause evaluation was adequate and effectively identified the primary and contributing causes for this event. The completed and proposed corrective actions, including actions to prevent recurrence, appropriately addressed the results of your root cause evaluation and your implementation schedule was consistent with the overall safety significance of the problem. As such, the inspection objectives of Inspection Procedure 95001, Inspection For One Or Two White Inputs In A Strategic Performance Area, have been satisfied. Given your acceptable performance in addressing the problems associated with this event, the White finding associated with this issue will only be considered in assessing plant performance for a total of four quarters in accordance with the guidance in Inspection Manual Chapter (IMC) 0305, Operating Reactor Assessment Program.
In accordance with 10 CFR 2.390 of the NRCs Rules of Practice, a copy of this letter and its enclosure 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/
, Chief Reactor Projects Branch 6 Division of Reactor Projects Docket Nos.: 50-390 License Nos.: NPF-90 Enclosure: NRC Supplemental Inspection Report 05000390/2006010 w/Attachment: Supplemental Information
_________________________
OFFICE RII:DRP RII:DRP SIGNATURE LWG per email LWG NAME BAnderson LGarner DATE 06/27/2006 06/27/2006 6/ /2006 6/ /2006 6/ /2006 6/ /2006 6/ /2006 E-MAIL COPY?
YES NO YES NO YES NO YES NO YES NO YES NO YES NO
Ashok S. Bhatnagar Senior Vice President Nuclear Operations Tennessee Valley Authority Electronic Mail Distribution Larry S. Bryant, Vice President Nuclear Engineering&Technical Services Tennessee Valley Authority Electronic Mail Distribution Michael D. Skaggs Site Vice President Watts Bar Nuclear Plant Tennessee Valley Authority Electronic Mail Distribution Preston D. Swafford Senior Vice President Nuclear Support Tennessee Valley Authority 6A Lookout Place 1101 Market Street Chattanooga, TN 37402 General Counsel Tennessee Valley Authority Electronic Mail Distribution John C. Fornicola, Manager Nuclear Assurance and Licensing Tennessee Valley Authority Electronic Mail Distribution Glenn W. Morris, Manager Corporate Nuclear Licensing and Industry Affairs Tennessee Valley Authority Electronic Mail Distribution Paul L. Pace, Manager Licensing and Industry Affairs Watts Bar Nuclear Plant Tennessee Valley Authority Electronic Mail Distribution Jay Laughlin, Plant Manager Watts Bar Nuclear Plant Tennessee Valley Authority Electronic Mail Distribution County Executive Rhea County Courthouse 375 Church Street, Suite 215 Dayton, TN 37321-1300 County Mayor P. O. Box 156 Decatur, TN 37322 Lawrence E. Nanney, Director TN Dept. of Environment & Conservation Division of Radiological Health Electronic Mail Distribution Ann Harris 341 Swing Loop Rockwood, TN 37854 James H. Bassham, Director Tennessee Emergency Management Agency Electronic Mail Distribution Distribution (See page 4)
Report to K. from Malcolm Widmann dated June 27, 2006.
SUBJECT:
WATTS BAR NUCLEAR PLANT - NRC SUPPLEMENTAL INSPECTION REPORT NO. 05000390/2006010 Distribution w/encl:
D. Pickett, NRR C. Evans (Part 72 Only)
L. Slack, RII EICS OE Mail (email address if applicable)
RIDSNRRDIRS PUBLIC
Enclosure U. S. NUCLEAR REGULATORY COMMISSION
REGION II
Docket No.:
License No.:
Report No.:
006010 Licensee:
Tennessee Valley Authority Facility:
Watts Bar Nuclear Power Plant Location:
1260 Nuclear Plant Road Spring City, TN 37381 Dates:
May 31 - June 2, 2006 Inspector:
Brian C. Anderson Resident Inspector, Vogtle Electric Generating Plant Approved by:
, Chief Reactor Projects Branch 6 Division of Reactor Projects
Enclosure
SUMMARY OF FINDINGS
IR 05000390/2006010; 05/31/2006 - 06/02/2006; Tennessee Valley Authority (TVA), Watts Bar
Nuclear Power Plant. Supplemental inspection for a White finding related to the failure to implement shutdown procedures which resulted in multiple actuations of pressurizer power operated relief valves (PORVs).
This inspection was conducted by a resident inspector from Vogtle Electric Generating Plant.
No findings of significance were identified. The Nuclear Regulatory Commissions (NRCs)program for overseeing the safe operation of commercial nuclear power reactors is described in NUREG-1649, Reactor Oversight Process, Revision 3, dated July 2000.
This supplemental inspection was performed by the NRC to assess Tennessee Valley Authoritys evaluation and corrective actions associated with a White finding related to the failure to implement shutdown procedures which resulted in multiple actuations of pressurizer PORVs. The performance issue for the finding was previously characterized as having low to moderate risk significance (White) in the NRC Final Significance Determination letter (IR 05000390/2006007), dated April 7, 2006.
During this supplemental inspection, which was performed in accordance with Inspection Procedure 95001, Inspection for One or Two White Inputs In a Strategic Performance Area, the NRC concluded that the licensees problem identification and root cause analysis was adequately addressed the results of the root cause evaluation.
Given the licensees acceptable performance in addressing the problems with this event, the White finding associated with this issue will only be considered in assessing plant performance for a total of four quarters in accordance with the guidance in IMC 0305, Operating Reactor Assessment Program. Implementation of the licensees corrective actions will be reviewed during a future inspection.
NRC-Identified and Self-Revealing Findings
No findings of significance were identified.
Licensee-Identified Violations
None.
REPORT DETAILS
Inspection Scope This supplemental inspection was performed by the NRC to assess the Tennessee Valley Authoritys evaluation and corrective actions associated with a low-to-moderate risk significant (White) finding applicable to Watts Bar Unit 1. The White finding was in the Barrier Integrity Cornerstone in the reactor safety strategic performance area. The performance issues associated with this finding were initially characterized in NRC Inspection Report (IR) 05000390/2005002 as an unresolved item (URI), subsequently as greater than Green in NRC IR 05000390/2005013, and later characterized as White in the NRC Final Significance Determination letter (IR 05000390/2006007), dated April 7, 2006. The inspection involved a review of the licensees problem identification, root cause analysis and corrective actions associated with this White finding.
The inspector assessed the adequacy of the licensees root cause analysis, determined if appropriate corrective actions were specified and scheduled commensurate with risk, and determined if the proposed actions were sufficient to prevent recurrence. This assessment included a review of the licensees Problem Evaluation Reports (PERs);root cause and apparent cause analyses; completed and scheduled corrective actions; programmatic and operational procedures; related drawings and documents; and interviews with key plant personnel.
Evaluation of Inspection Requirements 02.01 Problem Identification a.
Determination of who identified the issue and under what conditions On February 22, 2005, while transitioning to solid water operations, both pressurizer power operated relief valves (
multiple times during a two hour period. The block valve for PORV 1-RFV-63-340A had been closed to reduce containment gas problems via leakage from the valve packing.
Thus this PORV did not actually relieve pressure during a total of seven actuations.
However, PORV 1-RFV-63-334D actuated a total of five times to reduce pressure.
This self-revealing issue was documented by the licensee and was addressed through a root cause evaluation in PER 77176 and an apparent cause evaluation in PER 79910.
The White finding associated with this event was documented in NRC IR 05000390/2006007.
b. Determination of how long the issue existed and prior opportunities for identification
The normal charging flow control valve, 1-FCV-62-93, is an air-operated valve that controls the centrifugal charging pump (CCP) flow rate. Documented in the licensees corrective action program since September 2000, 1-FCV-62-93 operates erratically when a high differential pressure (dP) exists across the charging line (i.e., the high discharge pressure of the CCP to the lower pressure of the reactor coolant system).
This high dP operating condition normally occurs during plant startups and shutdowns.
In December 2004, the licensee approved a design change to reduce the erratic operation of 1-FCV-62-93 during high dP conditions. This design change was scheduled to be implemented concurrent with the transition to solid water operations as part of the next refueling outage, scheduled for February 2005. On February 22, 2005, licensee staff made inappropriate operational decisions during the transition to solid water operations. After returning the charging control valve to service following the implementation of the design change, procedural requirements were exceeded when 1-FCV-62-93 exhibited erratic operation. This erratic operation occurred following activities to transfer from bypass to normal charging and when operators transferred back to bypass charging.
Erratic operation of 1-FCV-62-93 had been documented in the licensees corrective action program since September 2000. A design change was being implemented to address the erratic operation of this valve. However, opportunities existed during design change scheduling and during operational decision-making to identify the potential problems that resulted in multiple actuations of pressurizer PORVs.
c.
Determination of the plant-specific risk consequences and compliance concerns associated with the issue The NRC IR 05000390/2006007, dated April 7, 2006, stated that the preliminary estimated delta core damage frequency (CDF) for this event was approximately 7E-5 per year. The NRC staff recognized that this value was based on a conservative assumption and conducted a reassessment using multiple approaches, both quantitative and qualitative. The reassessed quantitative CDF results were determined to be within the range of 1E-6 to 1E-5 per year. Therefore, based on the risk increase over the baseline scenario being between 1E-6 and 1E-5, the finding was characterized as White.
The licensee identified that the plant evolutions most susceptible to the event that occurred are plant startups and plant shutdowns. The licensee also recognized that inappropriate operational decisions were a key contributor to this event. Training and procedural modifications specifically addressed these aspects of the event.
d.
Assessment 02.02 Root Cause, Extent of Condition, and Extent of Cause Evaluations a.
Evaluation of methods used to identify root causes and contributing causes The inspector reviewed the methodology and results of the licensees root cause analysis as documented in the PER 77176; COPS pickup and the licensees apparent cause analysis as documented in PER 79910; Solid water OPS. The analyses used several formal systematic processes to identify root and contributing causes of the problems which led to multiple actuations of the pressurizer PORVs. These methodologies included Events and Causal Factors analysis and Common Cause Analysis in addition to less-formal, programmatically controlled analysis techniques.
The root cause analyses were conducted using the guidance contained in BP-250; Corrective Action Program Handbook. The analyses appropriately considered human performance, and process and hardware issues that contributed to the problems which led to this event. The analyses contained in the two PERs identified cause for this issue which resulted in the multiple pressurizer PORV actuations.
This root cause and related contributing causes were documented in the root cause analyses performed by the licensee. Corrective actions were developed to address the causes and to prevent recurrence.
b.
Level of detail of the root cause evaluation The inspectors review of the licensees root cause and apparent cause analyses determined that they had been performed to a level of depth commensurate with the significance of the issue and provided reasonable assurance that the root causes and contributing causes had been identified.
c.
Consideration of prior occurrences of the problem and knowledge of prior operating experience The inspector determined that during the root cause analysis conducted under PER 77176 and the apparent cause analysis conducted under PER 79910, the licensee reviewed both industry and internal operating experience to determine if any similar problems had been previously identified to aid in the resolution of the issues related to this event. This review included operating experience from within TVAs nuclear fleet and from other nuclear utilities.
d.
Consideration of potential common causes, extent of condition, and extent of cause of the problem The licensees root cause analysis considered, in part, activity scheduling, training, procedural guidance, and evolutions involving solid water operations to determine potential common causes and extent of condition. The inspector determined that the analysis did examine multiple disciplines, human performance, and different types of equipment and plant systems. Common cause considerations were focused on extent of condition. Extent of cause evaluation, associated with long standing equipment issues, mainly addressed valves with high differential pressure conditions and systems that operate under solid plant operations. Corrective actions were implemented to address procedural and training deficiencies identified as part of the consideration of common cause and extent of condition. The inspector concurred that the licensees actions properly identified and addressed common cause failures and the extent of condition.
e.
Assessment The licensees root cause and apparent cause analyses associated with the problems that led to multiple actuations of the pressurizer PORVs and resulted in a White finding were adequate and identified both root and contributing causes for this event.
Corrective actions have been developed to address each of these causes in the PERs containing the root cause and apparent cause analyses documentation.
02.03 Corrective Actions a.
Appropriateness of corrective actions The inspector reviewed all completed and pending corrective actions associated with this finding. The licensee identified nine corrective actions to address the root cause and contributing causes of this event. The corrective actions can be generally categorized as procedural enhancements, training, scheduling process improvements, and the repair or replacement of the normal charging flow control valve 1-FCV-62-93.
. The inspector determined that the corrective actions were clearly defined and appropriate for all identified causes of this event.
b.
Prioritization of corrective actions The inspector determined that the corrective actions associated with this event have been appropriately prioritized based on risk significance.
c.
Establishment of schedule for implementing and completing the corrective actions The inspector verified that all corrective actions associated with this finding are captured in the electronic corrective action program system. All pending corrective actions assign responsible individuals, identify completion dates and contain sufficient detail to ensure they are tracked and completed commensurate with their relative priority.
d.
Establishment of quantitative or qualitative measures of success for determining the effectiveness of the corrective actions to prevent recurrence
.
e.
Assessment Management Meetings
Exit Meeting Summary
The inspector presented the inspection results to Mr. J. Laughlin, Plant Manager, and other members of licensee management on June 2, 2006. The inspector confirmed that proprietary information was not provided or examined during the inspection.
ATTACHMENT:
SUPPLEMENTAL INFORMATION
KEY POINTS OF CONTACT
Licensee
- C. Allen, Mechanical Engineering
- M. DeRoche, Nuclear Assurance Manager
- J. Frisco, Engineering Manager
- J. Laughlin, Plant Manager
- L. McCormick, Design Manager Site Engineering
- P. Pace, Licensing and Industry Affairs Manager
- S. Robertson, Design Engineering
- P. Salkeld, Operations Support Superintendent
- M. Skaggs, Site Vice President, Watts Bar Nuclear Plant
- R. Stockton, Licensing Engineer Watts Bar Licensing
- D. Voeller, Maintenance and Modifications Support Manager
- D. White, Operations Manager
NRC
- J. Bartley, Senior Resident Inspector
- M. Widmann, Chief, Reactor Projects Branch 6, Division of Reactor Projects, RII
ITEMS OPENED AND CLOSED
Opened
None
Closed
None