ML062620445
| ML062620445 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 10/23/2006 |
| From: | Thomas Wengert NRC/NRR/ADRO/DORL/LPLIII-2 |
| To: | Dan Collins NRC/NRR/ADRO/DORL/LPLIII-2 |
| Wengert, Thomas | |
| References | |
| TAC MC5661 | |
| Download: ML062620445 (3) | |
Text
October 23, 2006 MEMORANDUM TO: Daniel S. Collins, Chief Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation FROM:
Thomas J. Wengert, Project Manager/RA/
Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
SUBJECT:
DAVIS-BESSE NUCLEAR POWER STATION, UNIT NO 1 - DRAFT REQUEST FOR ADDITIONAL INFORMATION (RAI), REGARDING THE DESIGN REQUIREMENTS FOR TORNADO MISSILE PROTECTION (TAC MC5661)
The attached draft RAI was transmitted by facsimile on September 18, 2006, to Mr. Tej Chowdhary of the Davis-Besse Nuclear Power Station in preparation for an upcoming conference call. Review of the RAI would allow the licensee to identify areas where clarification may be needed, as well as determine and agree upon a schedule for responding to the RAI.
This memorandum and its attachment do not convey a formal request for information or represent a Nuclear Regulatory Commission position.
Docket No. 50-346
Attachment:
As stated CONTACT: T. Wengert, NRR 301-415-4037
October 23, 2006 MEMORANDUM TO: Daniel S. Collins, Chief Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation FROM:
Thomas J. Wengert, Project Manager/RA/
Plant Licensing Branch III-2 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation
SUBJECT:
DAVIS-BESSE NUCLEAR POWER STATION, UNIT NO 1 - DRAFT REQUEST FOR ADDITIONAL INFORMATION (RAI), REGARDING THE DESIGN REQUIREMENTS FOR TORNADO MISSILE PROTECTION (TAC MC5661)
The attached draft RAI was transmitted by facsimile on September 18, 2006, to Mr. Tej Chowdhary of the Davis-Besse Nuclear Power Station in preparation for an upcoming conference call. Review of the RAI would allow the licensee to identify areas where clarification may be needed, as well as determine and agree upon a schedule for responding to the RAI.
This memorandum and its attachment do not convey a formal request for information or represent a Nuclear Regulatory Commission position.
Docket No. 50-346
Attachment:
As stated CONTACT: T. Wengert, NRR 301-415-4037 Distribution:
PUBLIC LPL3-2 R/F RidsNrrDorlLpl3-2 RidsNrrPMTWengert Accession No:ML062620445 Office LPL3-2/PM LPL3-2/BC Name TWengert DCollins Date 10/20/06 10/23/06 OFFICIAL RECORD COPY
DRAFT DRAFT REQUEST FOR ADDITIONAL INFORMATION DAVIS BESSE NUCLEAR POWER STATION, UNIT NO. 1 (DBNPS)
LICENSE AMENDMENT APPLICATION TO CHANGE DESIGN REQUIREMENTS FOR TORNADO MISSILE PROTECTION (TAC NO. MC5661)
DOCKET No. 50-346 On September 13, 2006 the Nuclear Regulatory Commission (NRC) staff held a telecon with the FirstEnergy Nuclear Operating Company (FENOC) to discuss FENOCs July 24, 2006 responses (ML062070158) to the NRCs Request for Additional Information (RAI) concerning FENOCs license amendment application dated January 11, 2005 (ML050140276) to change the design requirements for tornado missile protection for the Davis-Besse Nuclear Power Station, Unit No. 1 (DBNPS). During the telecon, the NRC technical staff requested the licensee to provide additional clarifications concerning its application of the Electric Power Research Institute (EPRI) Tornado Missile Risk Evaluation Methodology (TORMIS) model in support of the license amendment request. [Note: Question #6 was clarified via telecon between NRC and FENOC on October 3, 2006.]
In order for the NRC staff to complete its review of the licensees amendment request, the NRC staff requests that the licensee provide responses to the following questions.
1.
Explain how utilizing a tornado frequency of 4.25E-04 per year instead of the USAR frequency of 6.3E-04 per year is appropriate for a site-specific modeling approach.
2.
Regarding the selection of wind field parameters such that the ratio of near ground wind velocity to velocity at 33 feet elevation (V0/V33) is equal to a value of 0.82: confirm whether this is a variable or fixed value in the model.
- 3.
Describe how variance reduction parameters are used in the modeling and explain why the parameters are appropriate.
- 4.
Explain why the number of tornado simulations and histories included in the modeling is adequate.
- 5.
Provide additional clarification on how area ratioing was performed and explain how it is conservative and appropriate for use in the model.
- 6.
Confirm that the complete missile spectrum, incorporated as a manual input in the TORMIS code, was used in the EPRI TORMIS evaluation (as opposed to the default value which uses only 6 or 7 NRC missiles).