Text

NRC Generic Letter 2004-02 Request for an Extension to the Completion Date for Ex-Vessel Downstream Effects Evaluations
	ML081070252
Person / Time
Site:	Turkey Point
Issue date:	04/14/2008
From:	Stall J; Florida Power & Light Co
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	GL-04-002, L-2008-073
	Download: ML081070252 (4)
	v • d • e

0 IPL.

Florida Power & Light Company, 700 Universe Boulevard, Juno Beach, FL 33408 APR 1 4 2008 U. S. Nuclear Regulatory Commission L-2008-073 ATTN: Document Control Desk 10 CFR 50.54(f) 11555 Rockville Pike Rockville, Maryland 20852 Re: Florida Power and Light Company Turkey Point Unit 4 Docket No. 50-251 NRC Generic Letter 2004-02 Request for an Extension to the Completion Date for Ex-Vessel Downstream Effects Evaluations

References:

(1) Letter L-2005-181 from J. A. Stall (FPL) to U. S. Nuclear Regulatory Commission "NRC Generic Letter 2004-02 Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized Water Reactors - Second Response,"

dated September 1, 2005 (2) Generic Letter 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation during Design Basis Accidents at Pressurized-Water Reactors," dated September 13, 2004 (3) Letter L-2006-028 from J. A. Stall (FPL) to U. S. Nuclear Regulatory Commission "Supplement to Response to NRC Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized Water Reactors,"

dated January 27, 2006 (4) Letter from B. T. Moroney (U. S. Nuclear Regulatory Commission) to J. A. Stall (FPL) "Turkey Point Plant, Unit No. 4 - Approval of GSI-191/GL 2004-02 Extension Request (TAC No. MC4726)," dated April 13, 2006 (5) Letter L-2008-033 from William Jefferson, Jr. (FPL) to U. S. Nuclear Regulatory Commission "Supplemental Response to NRC Generic Letter 2004-02, 'Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors'," dated February 28, 2008 an FPL Group company

Turkey Point Unit 4, Docket No. 50-251 L-2008-073, Page 2 of 4 By letter L-2005-181 (Reference 1) Florida Power and Light Company (FPL), the Licensee for Turkey Point Unit 4, submitted responses requested to information items 2(a) and 2(b) of Generic Letter (GL) 2004-02 (Reference 2). The responses indicated that corrective actions would be implemented to ensure that the Emergency Core Cooling System and Containment Building Spray recirculation functions under debris loading conditions would be in compliance with the Applicable Regulatory Requirements section of the Generic Letter when all modifications are completed by December 31, 2007.

Subsequently, by letter L-2006-028 (Reference 3), FPL requested an extension to the completion schedule until the end of the Unit 4 spring 2008 refueling outage. By letter dated April 13, 2006 (Reference 4), the NRC staff concluded that it was acceptable to extend the completion date for the corrective actions until the completion of the Turkey Point Unit 4 spring refueling outage (which at that time was scheduled to begin on April 27, 2008.). By letter L-2008-033 (Reference 5), FPL provided a supplemental response to GL 2004-02 for Turkey Point Unit 4 where FPL reconfirmed that a follow-up (updated) supplemental response to GL 2004-02 would be submitted within three months following the spring outage.

As discussed in a teleconference with the NRC staff on March 27, 2008, it was recently identified that the High Head Safety Injection (HHSI) pumps do not meet the shaft stiffness acceptance criteria utilizing the methodology in WCAP-16406-P, Revision 1. In accordance with the provisions (alternative analytical options) of that WCAP, a refined rotor dynamic analysis will be performed to determine if an increased wear limit is acceptable. In addition, a review of existing conservative margins may also be conducted to evaluate wear effects on the pumps. These two options are described in the WCAP. FPL plans to complete this analytical work by June 30, 2008; however, this date is later than the currently scheduled restart for Turkey Point Unit 4. Thus, FPL requests an extension for completing the ex-vessel downstream effects evaluations that support HHSI pump acceptance. If these additional tasks do not demonstrate acceptable results and additional corrective actions are required, FPL will contact the Commission. The results of the downstream effects evaluations will be provided to the NRC staff with the Turkey Point Unit 4 updated supplemental response discussed above.

The discussions that follow support FPL's request to extend the completion of these analyses until June 30, 2008.

Risk Estimate WCAP-1 6362, "PRA Modeling Template for Sump Blockage," provides a general model for sump blockage that was used to perform a simplified risk impact evaluation of extending the completion of Generic Letter 2004-02 actions at Turkey Point Unit 4. The risk impact was limited to large break loss of coolant accidents (LOCAs), because only

Turkey Point Unit 4, Docket No. 50-251 L-2008-073, Page 3 of 4 large break LOCAs are large enough to create enough debris to clog the containment sump. From NUREG/CR-6928, "Industry Average Performance for Components and Initiating Events at U. S. Commercial Nuclear Power Plants", the frequency of a large break LOCA is 1.33E-06 per year. Minimal credit was taken for mitigation of sump blockage. For Turkey Point Unit 4, mitigation includes providing make up fluid to the Unit 4 Refueling Water Storage Tank (RWST) to allow extended injection, and starting the Unit 3 Safety Injection pumps for injection from the Unit 3 RWST. These mitigating actions are based on steps in the Emergency Operating Procedures. A screening value of 0.2 was used for the probability of failing to successfully perform these mitigating activities. The calculated increase in the core damage frequency due to sump clogging is therefore (1.33E-06 per year) x (0.2) = 2.66E-07 per year, which is well below the Regulatory Guide 1.174 definition of less than 1 E-06 per year for a "very small change" in core damage frequency. Therefore, extending the completion date for the ex-vessel downstream effects evaluations, until June 30, 2008, does not pose a significant risk increase.

Permanent Modifications In addition to modifications made in the fall 2006 outage, the remaining permanent modifications are scheduled to be complete before startup from the current spring 2008 outage, as discussed in our letter L-2008-033 (Reference 5). Final modifications include replacement of interim sump strainers with the final/permanent sump strainer system, replacement of existing Reactor Coolant Pump insulation with reflective metallic insulation, and replacement of mechanical seals and removal of the cyclone separators on the containment spray pumps.

Additional Supporting Activities Also, as discussed in our letter L-2008-033 (Reference 5), other supporting activities including analysis, testing and administrative/procedural changes will be completed by the end of the current spring outage. These include coating tests that support a qualified coating Zone Of Influence of 4.0D; integrated debris and chemical effects testing to validate the strainer design (large flume test); walkdowns to identify potential recirculation flow path chokepoints and quantities of latent and miscellaneous debris in the containment; programmatic activities to control the quantity of unqualified/degraded coatings in containment; assessment that current containment housekeeping procedures are acceptable; and configuration control of insulation within containment.

Conclusion In summary, with the exception of the requested analysis extension for the HHSI pumps to June 30, 2008, FPL will have completed planned GL 2004-02 improvements to Turkey Point Unit 4 by the completion of the spring 2008 outage. This results in significantly improved safety margins associated with the containment sumps.

Turkey Point Unit 4, Docket No. 50-251 L-2008-073, Page 4 of 4 It is requested that the NRC respond to this extension request by May 1, 2008.

This information is provided pursuant to the requirements of Section 182a of the Atomic Energy Act of 1954, as amended, and 10 CFR 50.54(f).

Please contact Rajiv S. Kundalkar at (561) 694-4848 if you have any questions regarding this request.

I declare under penalty of perjury that the foregoing is true and correct.

Executed on April / 4- , 2008 Sincerely yours, J. A. Stall Senior Vice President, Nuclear and Chief Nuclear Officer cc: Regional Administrator, Region II USNRC Project Manager, Turkey Point Senior Resident Inspector, USNRC, Turkey Point