ML20128N362
| ML20128N362 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 10/10/1996 |
| From: | Horn G NEBRASKA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEB-96-003, IEB-96-3, NLS960189, NUDOCS 9610160367 | |
| Download: ML20128N362 (6) | |
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GENEROL OFFICE m%'
P.O. 80X 499. COLUMBUS. NEBRASKA 68602-0499
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G. R. HORN Senior Vice President, Energy Supply (402) 563-5518 NLS960189 October 10,1996 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001 Gentlemen:
Subject:
Response to NRC Bulletin 96-03 Cooper Nuclear Station, NRC Docket 50-298, DPR-46
Reference:
- 1. NRC Bulletin 96-03 dated May 6,1996," Potential Plugging of Emergency Core Cooling Suction Strainers by Debris in Boiling-Water Reactors"
- 2. Letter BWROG-94034 to A. C. Thadani(USNRC) from L. A. England (BWROG) dated March 24,1994, " Submittal of BWROG Interim Safety Assessment and Operator Guidance in Response to NRC Bulletin 93-02, Supplement 1"
- 3. Letter to USNRC from G. R. Horn (NPPD) dated June 10,1993, " Response to NRC Bulletin 93-02"
- 4. Letter to USNRC from G. R. Horn (NPPD) dated April 18.1994, " Response to NRC Bulletin 93-02, Supplement 1, Debris Plugging ciEmergency Core Cooling Suction Strainers"
" Response to NRC Bulletin 95 Unexpected Clogging of RHR Suction Strainers" This submittal provides the Nebraska Public Power District's (District's) 180 day response to NRC Bulletin 96-03 (Reference 1). The District intends to comply with the requirements j/
of said bulletin through the installation of a large capacity passive strainer design. The District is planning to implement this modification by the end of the first refueling outage starting after January 1,1997 (RE17, currently scheduled for March 1997) provided generic design considerations are finalized to support our niilestone schedule established for implementation during RE17. Delays in final design approval, material procurement, or strainer fabrication and delivery beyond the scheduled milestone dates would cause the District to defer installation until RE18 (currently scheduled for September 1998). Due to the nature of the design, no changes to the Technical Specifications will be required.
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NLS960189 October 10,1996 l
Page 2 of 4 Reason for Implementation Date Deferral The District is vigorously pursuing installation during RE17 as demonstrated in the attached milestone schedule. However, due to uncertainties associated with the final issuance of the Utility Resolution Guidance (URG) document, the District is concerned about the technical and financial risks associated with a firm commitment to complete this installation during RE17.
The District's design will be based on calculational methodologies developed by the BWR Owners' Group (BWROG) ECCS Suction Strainer Committee as documented in the URG.
This document has been provided to the Staffin draft form, resulting in numerous comments, and has yet to be formally submitted. Because the resolution of these comments has the potential to affect design assumptions, the District is reluctant to finalize the design and initiate citainer fabrication until the URG review process is completed. Therefore, delays introiucea c: a result of comment resolution and URG final issuance after December 16,1996 (i.e, the milestone date for design finalization), would have a direct impact to the current RE17 window.
Accordingly, the District willimplement the strainer modification during RE17 provided the final issuance of the URG is on or before December 16,1996, and the final assumptions do not vary significantly from the assumptions used in our conceptional design. Final issuance of the URG following this date will result in the District deferring installation until RE18.
Safety Implications and Mitigative Stiatecies for Deferred Implementation The safety implications for the current strainer configuration have been addressed under General Electric Safety Assessment GE-NE-A0005845-01,"BWR Emergency Core Cooling System Suction Strainers," previously transmitted to the NRC under Reference 2.
Assuming the strainer modification is deferred to RE18, the following mitigative actions in addition to those taken in response to NRC Bulletin 93-02 (including Supplement 1) and NRC Bulletin 95-02 (as documented in References 3,4, and 5) will be taken:
- 1. The suppression pool will be cleaned during RE17. This cleaning will provide an accurate basis on which to determine the rate of sludge generation and will demonstrate the effectiveness of foreign material exc!usion and housekeeping practices.
- 2. The volume of fibrous and calcium silicate type insulation in the drywell susceptible to transport following a loss-of-coolant accident will be further reduced during RE17. This will be accomplished through the use of reflective metallic insulation. Targeted areas include approximately 144 feet ofinstrumentation piping, approximately 57 feet of Standby Liquid Control system piping, chilled water supply and return piping, head vent piping, and isolated sections of Reactor Water Clean-Up system piping.
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NLS960189 October 10,1996 Page 3 of 4 These actions (both those taken in response to previous bulletins and those committed above) provide adequate assurance of suction strainer operability should the installation be deferred to RE18.
Should you have any questions concerning this matter, please contact me.
i Sincerely, 9~~~
In
'o ice President, Energy Supply
/crm Attachment ec: Regional Administrator USNRC - Region IV Senior Project Manager USNRC - NRR Project Directorate IV-1 Senior Resident Inspector USNRC NPG Distribution 1
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NLS960189 October 10,1996 Page 4 of 4 STATE OF NEBRASKA
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PLATTE COUNTY
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G. R. Horn, being first duly sworn, deposes and says that he is an authorized representative of the Nebraska Public Power District, a public corporation and political subdivision of the State of Nebraska; that he is duly authorized to submit this correspondence on behalf of Nebraska Public Power District; and that the statements contained herein are true to the best of his knowledge and belief.
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G. R. Horn Subscribed in my presence and sworn to before me this /C day of A M r,1996.
OtRAttiotARY Stateofileiwah 1[L ter Bes. !S, NO'tAItY[fUBLIC l
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to NLS960189 l
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MILESTONE SCHEDULE FOR INSTALLATION DURING RE17 Date Milestone September 12,1996 Contract awarded for conceptual design document.
October 8,1996 Conceptual design document received by the District.
November 14,1996 Contract to be awarded for strainer design, fabrication, and installation.
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December 16,1996 Draft design to be submitted to the District and fabrication to begin upon District's approval.
January 6,1997 Detailed design to be submitted to the District for approval.
January 15,1997 Design modification package to be submitted for the District's review.
February 17,1997 District's review of the modification package is to be completed.
March 17,1997 Strainer to be at Cooper Nuclear Station for receipt inspection.
March 28,1997 Refueling outage to begin.
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ATTACHMENT 3 LIST OF NRC COMMITMEMTS' l
Correspondence No: NLS960189 The following table identifies those actions committed to by the District in this document. Any other actions discussed in the submittal. represent intended or planned actions by the District. They are described to the NRC for the NRC's information and are not regulatory commitments.
Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments COMMITTED DATE COMMITMENT OR OUTAGE The District will implement the strainer modification during RE17 provided the final issuance of the URG is on RE17 or before December 16, 1996, and the final assumptions do not vary significantly from the assumptions used in our conceptional design.
If the URG is finalized following December 16, 1996, RE18 implement the strainer modification by the end of the second refueling outage starting after January 1, 1997.
If the strainer modification is deferred to RE18, perform RE17 a suppression pool cleaning during the next refueling outage.
If the strainer modification is deferred to RE18, further l'
reduce the volume of fibrous and calcium silicate type RE17 insulation in the drywell susceptible to transport l
following a loss-of-coolant accident.
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l PROCEDURE NUMBER 0.42 l
REVISION NUMBER 1.2 l
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