ML071500391

Report of Changes to the Emergency Core Cooling System Evaluation Model in Accordance with 10 CFR 50.46(a)(3) for the Period of January 1, 2006 to December 31, 2006

ML071500391
Person / Time
Site:	Davis Besse
Issue date:	05/25/2007
From:	Bezilla M FirstEnergy Nuclear Operating Co
To:	Document Control Desk, NRC/NRR/ADRO
References
3343
Download: ML071500391 (7)

Text

FENOC 5501 North State Route 2 FirstEnergyNuclearOperatingCompany Oak Harbor, Ohio 43449 Mark B. Bezilla 419-321-7676 Vice President- Nuclear Fax. 419-321-7582 Docket Number 50-346 10 CFR 50.46 License Number NPF-3 Serial Number 3343 May 25, 2007 United States Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555-0001

Subject:

Davis-Besse Nuclear Power Station Report of Changes to the Emergency Core Cooling System Evaluation Model in Accordance with 10 CFR 50.46(a)(3)

Ladies and Gentlemen:

In accordance with 10 CFR 50.46(a)(3), the FirstEnergy Nuclear Operating Company (FENOC) hereby submits the annual report for changes and errors to the Emergency Core Cooling System (ECCS) Evaluation Model (EM) used at the Davis-Besse Nuclear Power Station (DBNPS). This report covers the period of January 1, 2006, to December 31, 2006.

The annual report is included as Attachment 1. Attachment 2, Commitment List, identifies that there are no commitments contained in this letter.

If there are any questions or if additional information is required, please contact Mr. Raymond A. Hruby, Jr., Manager - Regulatory Compliance, at (419) 321-8000.

Very truly yours, Mark B. Bezilla GMW/s Attachments ANOA

Docket Number 50-346 License Number NPF-3 Serial Number 3343 Page 2 of 2 cc: Regional Administrator, NRC Region III DB-1 NRC/NRR Project Manager DB-1 Senior NRC Resident Inspector Utility Radiological Safety Board

Docket Number 50-346 License Number NPF-3 Serial Number 3343 Attachment I Page 1 of 4 Annual Report of Changes to the 10 CFR 50.46 Emergency Core Cooling System Evaluation Model for the Davis-Besse Nuclear Power Station 10 CFR 50.46 (a)(3) states that each holder of an operating license shall report to the Nuclear Regulatory Commission (NRC) at least annually each change or error in an acceptable Emergency Core Cooling System (ECCS) Evaluation Model (EM) or in the application of such a model that affects the calculation of Peak Cladding Temperature (PCT).

EM General Description The Babcock and Wilcox Nuclear Technologies (BWNT) evaluation model (EM) is applicable to all Babcock & Wilcox (B&W) designed pressurized water reactors for large and small-break loss-of-coolant accident (LOCA) analyses for Zircaloy or M5 cladding. The NRC-approved topical report for this EM is BAW-10192P-A, Rev. 0 (Reference 1).

The large-break LOCA EM consists of four computer codes:

1. BAW-10164P-A, RELAP5/MOD2-B&W: computes the system, core, and hot rod response during blowdown (Reference 2),

2. BAW-10171P-A, REFLOD3B: calculates the time for refill of the lower plenum and core reflood rate (Reference 3),

3. BAW-10095-A, CONTEMPT: computes the Containment Vessel's pressure response (Reference 4) and,

4. BAW- 10166P-A, BEACH (the RELAP5/MOD2-B&W reflood heat transfer package): determines the hot pin thermal response during refill and reflood phases (Reference 5).

The small-break LOCA EM consists of two codes:

1. BAW-10164P-A, RELAP5/MOD2-B&W: computes the system, core, and hot rod response during the transient (Reference 2) and,

2. BAW-10095-A, CONTEMPT: computes the Containment Vessel's pressure response (Reference 4), if needed.

An NRC-approved fuel performance code (currently BAW- 101 62P-A, TACO3 (Reference 6) or BAW-101 84P-A, GDTACO (Reference 7)) is used to supply the fuel rod steady-state conditions at the beginning of the small or large-break LOCA. These codes are approved for use with M5 cladding as discussed in BAW-10227P-A (Reference 8).

Docket Number 50-346 License Number NPF-3 Serial Number 3343 Page 2 of 4 BWNT LOCA Evaluation Model Error Corrections or Changes There were no error corrections or changes during 2006.

BWNT LOCA Evaluation Model Generic Analyses No generic analyses were performed during 2006 that were applicable to Davis-Bessel EM Application Changes and Errors SBLOCA Analyses Application Error Correction A complete spectrum of SBLOCA break sizes was analyzed with a 4-second Main Feedwater (MFW) constant flow period due to double accounting of the 2-second delay that was targeted.

The resulting effect of this error on the SBLOCA spectrum was evaluated and results are documented in Reference 9. A MFW coastdown sensitivity study was performed as part of the evaluation. The evaluation concluded that the overall PCT predicted for the spectrum of break sizes is reflected in the 2- or 4-second MFW flow period results. The limiting break size may change as the MFW flow interval is varied; however, there is no change in the predicted PCT.

" Application Error Correction - MFW constant flow period.

" Evaluations were performed, including a MFW sensitivity study to address the changes to the SBLOCA spectrum. The effect on the reported licensing PCT was 0 'F.

Mixed-Core Mark-B-HTP LOCA Analysis for Cycle 15 Mixed-core Mark-B-HTP LBLOCA and SBLOCA analyses were performed to support licensing of the new Mark-B-HTP fuel assembly design at Davis-Besse beginning with Fuel Cycle 15.

These analyses consisted of LBLOCA and SBLOCA analyses that considered the Mark-B-HTP fuel assembly surrounded by Mark-B 1OK, Mark-B 12 or Mark-B 1 OM fuel assemblies.

The Fuel Cycle 15 licensing calculations were completed in 2005 in order to support operation starting in the spring of 2006. The Fuel Cycle 15 analyses resulted in a PCT increase of 50 TF.

Therefore, these results were considered to have a 30-day reporting requirement and were included with the 2005 yearly report items (letter Serial Number 3258 dated May 8, 2006).

Docket Number 50-346 License Number NPF-3 Serial Number 3343 Attachment I Page 3 of 4 Summary A summary of the changes for the reporting period and the corresponding PCTs is provided in Table 1.

References

1. AREVA/FANP Proprietary Topical Report BAW-10192P-A, Rev. 0, "BWNT LOCA -

BWNT Loss-of-Coolant Accident Evaluation Model for Once-Through Steam Generator Plants," June 1998.

2. AREVA/FANP Proprietary Topical Report BAW-10164P-A, Rev. 4, "RELAP5/MOD2-B&W - An Advanced Computer Program for Light Water Reactor LOCA and Non-LOCA Transient Analysis," November 2002.

3. AREVA/FANP Proprietary Topical Report BAW- 10171 P-A, Rev. 3, "REFLOD3B -

Model for Multinode Core Reflooding Analysis," December 1995.

4. AREVA/FANP Proprietary Topical Report BAW-10095-A, Rev. 1, "CONTEMPT -

Computer Program for Predicting Containment Pressure-Temperature Response to a LOCA," April 1978.

5. AREVA/FANP Proprietary Topical BAW-1 0166P-A, Rev. 5, "BEACH - A Computer Program for Reflood Heat Transfer During LOCA," November 2003.

6. AREVA/FANP Proprietary Topical Report BAW-10162P-A, Rev. 0, "TACO3 Fuel Pin Thermal Analysis Code," October 1989.

7. AREVA/FANP Proprietary Topical Report BAW-101 84P-A, Rev. 0, "GDTACO Urania

- Gadolinia Fuel Pin Thermal Analysis Code," February 1995.

8. AREVA/FANP Proprietary Topical Report BAW-1 0227P-A, Rev. 1, "Evaluation of Advanced Cladding and Structural Material (M5) in PWR Reactor Fuel," June 2003.

9. Davis-Besse calculation number, C-NSA-064.02-036, Rev. 1, "DB-1 LOCA Summary Report," January 17, 2007.

Docket Number 50-346 License Number NPF-3 Serial Number 3343 Attachment 1 Page 4 of 4 Table 1 Evaluation Model Application Summary PlantName: Davis-Besse Unit I LOCA Spectrum Utility Name: FirstEnergy Mk-BIOM Mk-BJOK Mk-B12 Mk-B-HTP SBLOCI LBLOCA LBLOCA LBLOCA LBLOCA Item Reporting Description PCT or (Delta PCT)

1. Category ______________________________

<2,102 OF 2,102 OF 2,099 OF 2,095 OF 1,555 OF Licensing Basis at Beginning of Cycle 15 (April2006) Estimate Analyzed Analyzed Analyzed Analyzed EM R0.6 EM RO.6 EM RO.6 EM RO.9 EM RO.9 2006 Licensing Activity Application Error 1 Apiction e SBLOCA Analyses Application Error Correction. N/A N/A N/A N/A (+0 F)

<2,102 OF 2,102 OF 2,099 OF 2,095 OF 1,555 OF Licensing Basis at End of 2006 Estimate Analyzed Analyzed Analyzed Analyzed EM RO.6 EM RO.6 EM RO.6 EM RO.9 EM RO.9

Docket Number 50-346 License Number NPF-3 Serial Number 3343 Page 1 of 1 COMMITMENT LIST The following list identifies those actions committed to by the Davis-Besse Nuclear Power Station in this document. Any other actions discussed in the submittal represent intended or planned actions by Davis-Besse. They are described only as information and are not regulatory commitments. Please notify the Manager, Regulatory Compliance, at (419) 321-8000 at Davis-Besse of any questions regarding this document or associated regulatory commitments.

COMMITMENTS DUE DATE None N/A