ET 08-0037, Request for Extension of Completion Date for Corrective Actions Associated with NRC Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors

Request for Extension of Completion Date for Corrective Actions Associated with NRC Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors

ML081790152
Person / Time
Site:	Wolf Creek
Issue date:	06/20/2008
From:	Garrett T Wolf Creek
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
ET 08-0037, GL-04-002
Download: ML081790152 (5)

Text

WSLF CREEK rNUCLEAR OPERATING CORPORATION Terry J. Garrett Vice President, Engineering June 20, 2008 ET 08-0037 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555

Reference:

1) Letter WO 07-0056, dated December 5, 2007 from T. J. Garrett, WCNOC, to USNRC

2) Letter ET 08-0003, dated February 29, 2008, from T. J. Garrett, WCNOC, to USNRC

3) Letter dated November 27, 2007 from USNRC to A. Pietrangelo, Nuclear Energy Institute

Subject:

Docket No. 50-482: Request for Extension of Completion Date for Corrective Actions Associated with NRC Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors" Gentlemen:

By letter dated December 5, 2007 (Reference 1), Wolf Creek Nuclear. Operating Corporation (WCNOC) committed to completing all corrective actions associated with Generic Letter (GL) 2004-02 prior to or on June 30, 2008. Although plant-specific tests at the vendor testing facility were completed, the vendor documentation necessary for WCNOC to complete subsequent analyses and evaluations has been delayed. This submittal requests an extension for completion of remaining GL 2004-02 corrective actions until September 30, 2008.

WCNOC has successfully completed testing performed at a special test facility at Alden Research Laboratory. The tests were performed based on an established test protocol with input from the NRC Staff. There have been a number of delays in completion of the test report and subsequent analysis due to the number of tests being performed for other licensees and competing resources for completion. WCNOC was present during testing for Wolf Creek Generating Station (WCGS) performed in January, 2008, and observed that adequate net positive suction head (NPSH) margin would be maintained. In addition,,the testing confirmed the effectiveness of the new strainer design and its resistance to blockage from the transported P.O. Box 411 / Burlington, KS 66839 / Phone: (620) 364-8831 An Equal Opportunity Employer M/F/HC/VET

ET 08-0037 Page 2 of 4 debris. The increase in head loss due to chemical effects was minimal. Bypass testing was also performed which is being evaluated in the downstream effects analysis. Therefore, corrective actions are nearly complete.

In SECY-06-0078, dated March 31, 2006, the NRC staff recognized that licensees may encounter situations that could delay the implementation of corrective actions as committed in response to GL 2004-02. SECY-06-0078 describes that proposed extensions to permit completion of corrective actions after December 31, 2007 may be acceptable if, based on the licensee's request, the staff determines that: "the licensee has a plant-specific technical/experimental plan with milestones and schedule to address outstanding technical issues with enough margin to account for uncertainties" and " the licensee identifies mitigative measures to be put in place prior to December 31, 2007, and adequately describes how these mitigative measures will minimize the risk of degraded ECCS and CSS functions during the extension period."

WCNOC has the following plant-specific technical/experimental plan with milestones and schedule to address outstanding technical issues with enough margin to account for uncertainties:

• Additional plant-specific tests that support assumptions and corresponding conclusions contained in the GL 2004-02 evaluations for WCGS were completed in January, 2008.

The testing included strainer performance testing, head loss testing and chemical effects/debris bypass testing including debris transport. Although plant-specific tests at the vendor testing facility were completed, the vendor documentation necessary for WCNOC to complete subsequent analyses and evaluations has been delayed.

WCNOC expects the submittal of the final test report from the vendor to occur by mid-August 2008.

• Following receipt of the final test report from the vendor, numerous additional actions are required by WCNOC to complete formal verification of design inputs, assumptions and conclusions of WCNOC calculations and evaluations conducted in response to issues identified in GL 2004-02. These activities include assessing the impact of the test results on strainer NPSH calculations, strainer bypass sampling impact on downstream effects analyses (in-vessel and ex-vessel), as well as potential impact on other Generic Letter 2004-02 corrective action evaluations. These activities also include compliance with 10 CFR 50, Appendix B requirements for design control, document control and quality assurance records. These activities will be complete by September 30, 2008.

The following mitigative measures were put in place prior to December 31, 2007 and continue to be in place:

Plant hardware modifications developed in response to issues identified in GL 2004-02, as described in Reference 1, are installed in WCGS and are supporting compliance with the regulatory requirements for long term cooling following a design basis loss of coolant accident. Hardware modifications include replacement of sump strainers with a total of 6623 square feet of surface area, and installation of debris barriers in the "A" and "D" loop entrances. The design approach is to maximize the capability of the strainer while minimizing the debris load to the extent practical.

ET 08-0037 Page 3 of 4 Implementation is complete for WCNOC plant administrative procedures and processes described in Reference 1 to support the GL 2004-02 hardware modifications and revised operating practices, as well as to support the assumptions, initial conditions and conclusions of the expected final version of GL 2004-02 related evaluations, when the evaluations are completed and documented. Administrative procedures and processes include implementation of changes to programmatic controls for design change processes and containment material controls, as well as implementation of a containment coatings assessment program and a containment latent debris assessment program.

" Interim compensatory measures implemented at WCGS in accordance with NRC Bulletin 2003-01, as described in Reference 2, remain in effect to minimize interim risks associated with post-accident debris blockage while GL 2004-02 evaluations are being completed. In accordance with NRC Bulletin 2003-01, these measures will remain in place at a minimum until all evaluations and corrective actions for GL 2004-02 are complete.

This letter transmits changes in WCNOC's regulatory commitments contained in References 1 and 2. Consistent with guidance in Reference 3 for licensees with approved extensions, WCNOC will submit an update to the supplemental response to GL 2004-02 describing the results of the testing and the implementation of calculations, evaluations and other changes described in Reference 1 within 90 days of completion of all actions needed to address GL 2004-02. The commitment changes are being submitted in accordance with guidance provided by industry document NEI 99-04, "Guidelines for Managing NRC Commitment Changes," as endorsed in Regulatory Issues Summary 00-017, "Managing Regulatory Commitments Made by Power Reactor Licensees to the NRC Staff." Attachment I lists the WCNOC commitments contained in this letter. Commitments contained in this letter supersede those previously contained in References 1 and 2.

If you have any questions concerning this matter, please contact me at (620) 364-4084, or Mr.

Richard Flannigan at (620) 364-4117.

Sincerely, Te arrett TJG/rlt Attachment cc: E. E. Collins (NRC), w/a V. G. Gaddy (NRC), w/a B. K. Singal (NRC) , w/a Senior Resident Inspector (NRC), w/a

ET 08-0037 Page 4 of 4 STATE OF KANSAS )

SS COUNTY OF COFFEY )

Terry J. Garrett, of lawful age, being first duly sworn upon oath says that he is Vice President Engineering of Wolf Creek Nuclear Operating Corporation; that he has read the foregoing document and knows the contents thereof; that he has executed the same for and on behalf of said Corporation with full power and authority to do so; and that the facts therein stated are true and correct to the best of his knowledge, information and belief.

By_____________________

Terry J. rrett Vice President Engineering SUBSCRIBED and sworn to before me this Xbday ofl*rL nl, 2008.

Notary Public (I Expiration Date 1kw //; ,I0/ I

Attachment I to ET 08-0037 Page 1 of 1 Regulatory Commitments The following table identifies revised due dates for those actions originally committed to by Wolf Creek Nuclear Operating Corporation in References 1 and 2. The numbering in this table is maintained consistent with Reference 1. Any other statements in this letter are provided for information purposes and are not considered to be regulatory commitments. Please direct questions regarding these commitments to Mr. Richard Flannigan, Manager Regulatory Affairs at Wolf Creek Generating Station, (620) 364-4117.

Regulatory Commitment Due Date

1. The following corrective action activities will be completed:

a. Using WCAP-16406-P, evaluate the effects of debris-laden fluid on a. September 30, systems and components downstream of the containment 2008 emergency sump strainers during the ECCS recirculation phase of design basis accidents.

b. Using NEI 04-07, evaluate the effects of design basis accident b. September 30, conditions on the ability of structures, systems and components 2008 upstream of the containment emergency sump strainers to mitigate the consequences of the analyzed accidents.

2. Submit an update to information contained in WCNOC's response to Within 90 days of Generic Letter 2004-02 Requested Information Item 2. completion of all GL 2004-02 actions

3. The following evaluations and testing will be completed:

b. Using NEI 04-07, perform a debris generation calculation for the b. September 30, analyzed design basis accidents. 2008

c. Using NEI 04-07, perform a debris transport calculation for the c. September 30, analyzed design basis accidents. 2008

d. Evaluate the impact of chemical effects on containment emergency d. September 30, sump strainer head loss during design basis accident conditions. 2008

e. Complete head loss testing of the replacement containment e. September 30, emergency sump strainer. 2008

f. Confirm that the available NPSH of the replacement containment f. September 30, emergency sump strainers during design basis accident conditions 2008 is in excess of the required NPSH.

4. Complete the final site acceptance review of the Westinghouse September 30, evaluation team analysis summary report. 2008

5. The following items will be completed:

c. Modify safety injection system components, if required, based on c. September 30, the results of the downstream effects evaluation. 2008

6. Remove the containment spray system pump cyclone separators, if September 30, required, based on the results of the downstream effects evaluation. 2008

9. Implement all plant modifications and related administrative controls September 30, that support the NEI 04-07 analysis package. 2008