CPSES-200602416, Updated Response to Requested Information Part 2 of NRC Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors.

Updated Response to Requested Information Part 2 of NRC Generic Letter 2004-02, Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors.

ML063560392
Person / Time
Site:	Comanche Peak
Issue date:	12/13/2006
From:	Blevins M, Madden F TXU Power
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
CPSES-200602416, GL-04-002, TXX-06196
Download: ML063560392 (4)

Text

Power TXU Power Mike Blevins Comanche Peak Steam Senior Vice President &

Electric Statin Chief Nuclear Officer P. 0. Box 1002 (E01)

Glen Rose, TX 76043 Tek: 254 897 5209 Ref: #10CFR50.54(f)

Fax: 254 897 6652 mike.blevins@txu.com CPSES-200602416 Log # TXX-06196 December 13, 2006 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

SUBJECT:

UPDATED RESPONSE TO REQUESTED INFORMATION PART 2 OF NRC GENERIC LETTER 2004-02, "POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY RECIRCULATION DURING DESIGN BASIS ACCIDENTS AT PRESSURIZED-WATER REACTORS" REF: I. Letter Logged TXX-05162 from M. Blevins to the NRC dated September 1, 2005, "RESPONSE TO REQUESTED INFORMATION PART 2 OF NRC GENERIC LETTER 2004-02, POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY RECIRCULATION DURING DESIGN BASIS ACCIDENTS AT PRESSURIZED-WATER REACTORS"

2. NRC letter from M. Thadani (NRC) to M. Blevins dated February 9, 2006, Requesting Additional Information Re: Response to Generic Letter 2004-02

3. Letter Logged TXX-06062 from M. Blevins to the NRC dated March 31, 2006, "UPDATED RESPONSE TO REQUESTED INFORMATION PART 2 OF NRC GENERIC LETTER 2004-02, "POTENTIAL IMPACT OF DEBRIS BLOCKAGE ON EMERGENCY RECIRCULATION DURING DESIGN BASIS ACCIDENTS AT PRESSURIZED-WATER REACTORS"

4. NRC letter from J. Grobe (NRC) to A. Pietrangelo dated November 14, 2006, Nuclear Regulatory Commission Request for Additional Information to Pressurizer Water Reactor Licensees Regarding Responses to Generic Letter 2004-02 A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway . Comanche Peak

• Diablo Canyon . Palo Verde

• South Texas Project

• Wolf Creek

- >a TXX-06196 Page 2 of 4

Dear Sir or Madam:

The US Nuclear Regulatory Commission (NRC) issued Generic Letter 2004-02 on September 13, 2004 to 1) request that addressees perform an evaluation of the emergency core cooling system (ECCS) and containment spray system (CSS) recirculation functions in light of the information provided in the generic letter and, if appropriate, take additional actions to ensure system function, and 2) require addressees to provide the NRC a written response in accordance with I OCFR50.54(t).

Additionally the NRC requested that addressees submit information specified in part 2 of the generic letter to the NRC. The request was based on identified potential susceptibility of the pressurized water reactor (PWR) recirculation sump screens to debris blockage during design basis accidents requiring recirculation operation of ECCS or CSS and on the potential for additional adverse effects due to debris blockage of flow paths necessary for ECCS and CSS recirculation and containment drainage. Reference 1 provided the available information requested in part 2 of the generic letter as of September 1, 2005 and committed to update the information in the first quarter of 2006.

Subsequently, the NRC issued a request for additional information (RAI),

Reference 2, regarding the information provided in Reference 1. These RAIs cover a broad range of topics and are intended to support the NRC staff's ongoing review of industry activities to resolve Generic Safety Issue 191. Responses to the RAIs were requested within 60 days of the date of the letter transmitting the information requests.

TXU Power provided an update, Reference 3, to the infornation that was submitted per Reference I and revised commitment 27370.

TXU Power is providing further updates to commitment 27370 consistent with the latest infornation regarding GL 2004-02 completion and NRC guidance for response to the RAI in Reference 4. In addition, TXU Power has recently completed the 9 th

TXX-06196 Page 3 of 4 refueling outage for Unit 2. The following information is being provided in accordance with 10CFR50.54(f).

• ECCS sumps screens were replaced with new strainers increasing the surface area to over 4000 square feet per emergency sump.

The Unit 2 Refueling Water Storage Tank (RWST) Low-low setpoint and the ECCS switchover procedure were revised to support the strainers installed in Unit

2. The Refueling Water Storage Tank to Containment Spray Isolation valves were replaced to reduce closing time for switchover from injection to recirculation.

Control board instruments and controls and alarm were modified to support the setpoint change and enhance the operator interface for ECCS and spray switchover.

Various modifications were made to reduce recirculation water holdup volumes.

These modifications, in combination with the RWST changes above, increase the minimum post accident flood levels and net positive suction head (NPSH) margins Unit I changes are scheduled for completion prior to restart from Refueling Outage I RF 12, currently scheduled for Spring 2007.

Some activities such as chemical effects impact on required and available NPSH and Containment coatings still remain open and are not scheduled for resolution until the Fall of 2007. Therefore, the next update to GL 2004-02 will be provided within 90 days after completion of all activities on CPSES Units I and 2 for resolution of GSI-191 or December 31, 2007, whichever is earlier.

This letter contains one revised licensing commitment regarding CPSES Units 1 and 2.

Description of Commitment 27370 As a result of analyses, testing, and design evaluations not being fully (Revised) completed, an update to this response (modifications and maintenance actions) will be provided within 90 days after completion of all activities on CPSES Units I and 2for resolution of GSI-191 or December 31, 2007, whichever is earlier.

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TXX-06196 Page 4 of 4 Should you have any questions, please contact Mr. J. D. Seawright at (254) 897-0140.

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

Executed on December 13, 2006.

Sincerely, TXU Generation Company LP By: TXU Generation Management Company LLC Its General Partner Mike Blevins

/Fred W. Madden Director, Oversight and Regulatory Affairs JDS c - B. S. Mallett, Region IV M. C. Thadani, NRR Resident Inspectors, CPSES