ML060730021

Annual and 30-Day Reports of Loss-of-Coolant Accident Evaluation Model Changes

ML060730021
Person / Time
Site:	Cook
Issue date:	03/17/2006
From:	Tam P NRC/NRR/ADRO/DORL/LPLE
To:	Nazar M Indiana Michigan Power Co
References
TAC MC8409, TAC MC8410
Download: ML060730021 (6)

Text

March 17, 2006 Mr. Mano K. Nazar Senior Vice President and Chief Nuclear Officer Indiana Michigan Power Company Nuclear Generation Group One Cook Place Bridgman, MI 49106

SUBJECT:

DONALD C. COOK NUCLEAR PLANT (DCCNP), UNITS 1 AND 2 - ANNUAL AND 30-DAY REPORTS OF LOSS-OF-COOLANT ACCIDENT EVALUATION MODEL CHANGES (TAC NOS. MC8409 AND MC8410)

Dear Mr. Nazar:

The Nuclear Regulatory Commission (NRC) staff has reviewed the DCCNP letters dated December 28, 2004, April 29, and August 26, 2005, which reported errors and changes to the DCCNP Units 1 and 2 large-break and small-break loss-of-coolant accident (LBLOCA and SBLOCA) analyses of record. In telephone conferences on August 26, 2005, and January 17, 2006, the NRC staff discussed the information in these reports with DCCNP personnel Mr. K. Steinmetz, et al., and heard them clarify the intent of the information. Based on review of the referenced letters, as clarified in the telephone conferences, the NRC staff finds the information and the proposed schedules for reanalyses of DCCNP Units 1 and 2 LBLOCA and SBLOCA analyses of record acceptable. The enclosed safety evaluation provides details of the NRC staff's evaluation.

This completes the NRC efforts under the above TAC Nos.

Sincerely,

/RA/

Peter S. Tam, Senior Project Manager Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-315 and 50-316

Enclosures:

As stated cc w/encl: See next page

March 17, 2006 Mr. Mano K. Nazar Senior Vice President and Chief Nuclear Officer Indiana Michigan Power Company Nuclear Generation Group One Cook Place Bridgman, MI 49106

SUBJECT:

DONALD C. COOK NUCLEAR PLANT (DCCNP), UNITS 1 AND 2 - ANNUAL AND 30-DAY REPORTS OF LOSS-OF-COOLANT ACCIDENT EVALUATION MODEL CHANGES (TAC NOS. MC8409 AND MC8410)

Dear Mr. Nazar:

The Nuclear Regulatory Commission (NRC) staff has reviewed the DCCNP letters dated December 28, 2004, April 29, and August 26, 2005, which reported errors and changes to the DCCNP Units 1 and 2 large-break and small-break loss-of-coolant accident (LBLOCA and SBLOCA) analyses of record. In telephone conferences on August 26, 2005, and January 17, 2006, the NRC staff discussed the information in these reports with DCCNP personnel Mr. K. Steinmetz, et al., and heard them clarify the intent of the information. Based on review of the referenced letters, as clarified in the telephone conferences, the NRC staff finds the information and the proposed schedules for reanalyses of DCCNP Units 1 and 2 LBLOCA and SBLOCA analyses of record acceptable. The enclosed safety evaluation provides details of the NRC staff's evaluation.

This completes the NRC efforts under the above TAC Nos.

Sincerely,

/RA/

Peter S. Tam, Senior Project Manager Plant Licensing Branch III-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-315 and 50-316

Enclosures:

As stated cc w/encl: See next page DISTRIBUTION PUBLIC LPL3-1 R/F RidsNrrPMPTam RidsNrrLATHarris RidsOgcRp RidsAcrsAcnwMailCenter RidsNrrDorlLple RidsRgn3MailCenter FOrr Accession Number: ML060730021 OFFICE NRR/LPL3-1/PM NRR/LPL3-1/LA NRR/SPWB/BC NRR/LPL3-1/BC NAME PTam THarris JNakoski* LRaghavan DATE 03/16/06 03/15 /06 2/14/06* 03/17/06

• Safety evaluation transmitted by memo dated 2/14/06 OFFICIAL RECORD COPY

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION D. C. COOK NUCLEAR PLANT (DCCNP), UNITS 1 AND 2 DOCKET NOS. 50-315 AND 50-316 ANNUAL AND 30-DAY REPORTS OF LOSS-OF-COOLANT ACCIDENT EVALUATION MODEL CHANGES

1.0 INTRODUCTION

By letters dated December 28, 2004 (Accession No. ML050040216), April 29 (Accession No. ML051300368), and August 26, 2005 (Accession No. 052500285), Indiana Michigan Power Company, LLC (the licensee), reported errors and changes to the DCCNP Units 1 and 2 large-break and small-break loss-of-coolant accident (LBLOCA and SBLOCA) analyses of record (AOR). In telephone conferences on August 26, 2005, and January 17, 2006, the Nuclear Regulatory Commission (NRC) staff discussed these reports with DCCNP personnel and heard the licensees clarification of the above referenced submittals.

2.0 REGULATORY EVALUATION

The Commission's regulation at 10 CFR §50.46 requires that the emergency core cooling system (ECCS) be designed so that its calculated cooling performance following a postulated loss-of-coolant accident can be predicted by acceptable evaluation models. These models may prove to contain errors, or may have experienced changes, which are defined as "a calculated peak fuel cladding temperature difference by more than 50 oF from the temperature calculated for the limiting transient using the last acceptable model, or is a cumulation of changes and errors such that the sum of the absolute magnitudes of the respective temperature changes is greater than 50 oF." The regulation requires that the licensee shall report such change or error "within 30 days and include with the report a proposed schedule for providing a reanalysis or taking other action as may be needed to show compliance with §50.46 requirements."

3.0 TECHNICAL EVALUATION

3.1 Unit 1 LBLOCA The licensee reported that the AOR of 2038 oF has experienced at least 71 oF (including -11 oF, attributed as an absolute value due to cladding emissivity errors) of estimated change in peak cladding temperature ()PCT) added since the year 2000 when the AOR was performed, not including a 31 oF transition core penalty (which disappeared after one cycle). During the transition cycle, the estimated PCT is 2118 oF. Consistent with the 71 oF )PCT (greater than the 10 CFR 50.46 changes and errors sum of absolute values limit), the licensee submitted a report, and proposed a reanalysis schedule, associated with a March 2007 reload, using the

Westinghouse ASTRUM LBLOCA methodology. The licensees )PCT estimates were derived from calculations using the same BASH model as used to perform the AOR, assuring consistency of the )PCT estimates with the AOR. The licensee indicated that it is impractical to schedule fuel conversions (including reanalyses) for both DCCNP units in the same time period.

The licensees proposed reanalysis schedule (March 2007) for DCCNP Unit 1, is more expedited than for Unit 2, because Unit 1 has a significant number of fuel failures that could necessitate a forced outage if a number of additional failures were encountered.

3.2 Unit 1 SBLOCA The licensees AOR (1720 oF), done in year 2000, is normal for this design. However, since then, the AOR has experienced 3 major increases summing to an estimated 270 oF )PCT. The new estimated SBLOCA PCT is 1990 oF. This estimated PCT is high; however, the estimated PCT remains within regulatory limits with assurance that the PCT will not exceed 2200 oF.

Therefore, the NRC staff finds it acceptable for the licensee to schedule the reanalysis consistent with the proposed refueling outage (March 2007).

3.3 Unit 2 LBLOCA The licensee stated that the Unit 2 LBLOCA AOR (i.e., 2051 oF) performed in year 1995, has had at least 113 oF )PCT added, not including a -50 oF )PCT ZIRLO adjustment. The total estimated )PCT is 163 oF (sum of the absolute values of )PCT changes and errors), and the adjusted PCT is 2114 oF. Consistent with the 163 oF )PCT, which is greater than the 10 CFR 50.46 sum of absolute values limit, the licensee submitted a report, and proposed a reanalysis schedule associated with a March 2009 reload using the Westinghouse ASTRUM LBLOCA methodology. The licensees )PCT estimates were derived from calculations using the same BASH model as used to perform the AOR, thus assuring consistency of the )PCT estimates with the AOR. The licensee indicated that it is impractical to schedule fuel conversions (including reanalyses) for both DCCNP units in the same time period.

Because the licensee has determined that replacing failed fuel for DCCNP Unit 1 (including reanalysis), is more expedient than implementing a reanalysis for DCCNP Unit 2, the licensee plans to devote its resources on the Cook Unit 1 fuel activities, including reanalyses, in March 2007, and postpone the Unit 2 reanalyses to March 2009.

3.4 Unit 2 SBLOCA The licensee reported that the AOR (i.e., 1956 oF) performed in 1992, is normal for this design.

However, since then the AOR has experienced several changes, the absolute values of these changes summing to an estimated 354 oF )PCT. Given due consideration to the increases and decreases in PCT associated with the changes, the resulting estimated PCT is 1739 oF. The licensee performed an additional assessment of the Unit 2 SBLOCA AOR using an NRC-approved revision of the 1992 SBLOCA methodology NOTRUMP. The result was a 150 oF

)PCT benefit in the assessment of the SBLOCA PCT, bringing the estimated PCT down to 1589 oF; but this also raised the total absolute value of )PCT due to changes and errors to 504 o

F. The estimated )PCT is thus equivalent to about 54 percent of the SBLOCA temperature rise from pre-accident normal operating conditions and raises question about the fidelity of the

Unit 2 model for SBLOCA analyses. However, even if all the estimated )PCTs were added, the PCT would still be more than 150 oF below the 10 CFR 50.46 PCT limit.

Because the licensee has determined that replacing failed fuel for Unit 1 (including reanalysis),

is more expedient than implementing a reanalysis for Unit 2, the licensee plans to devote its resources on the Unit 1 fuel activities, including reanalyses, in March 2007, and postpone the Unit 2 reanalyses to March 2009. This schedule is acceptable to the NRC staff.

4.0 CONCLUSION

Based on the above evaluation, the NRC staff concludes that :

(1) The licensee has discovered, accounted for (by quantifying the effects of the reported changes and errors and of off-setting considerations for LBLOCA and SBLOCA analyses), and reported changes and errors in the LBLOCA and SMLOCA analyses of record for DCCNP Units 1 and 2 in accordance with 10 CFR 50.46(a)(3).

(2) The licensee has proposed schedules for reanalyses of both LBLOCA and SBLOCA for both units in accordance with 10 CFR 50.46(a)(3). The reanalysis schedules proposed for both units are acceptable. However, the licensees proposed schedules do not appear to have fully considered the accumulations of estimated )PCT corrections due to changes and errors. The )PCTs estimates have enhanced credibility because they are based on sensitivity analyses performed with DCCNP licensing ECCS analysis methodologies. In the case of Unit 2, the SBLOCA was reassessed using a different NRC-approved revision of the SBLOCA methodology from the version approved for Unit 2.

(3) The NRC staff finds the Unit 1 and Unit 2 ECCS errors and changes reports submitted by the licensee acceptable as discussed above, but suggest that the licensee implement a program of heightened vigilance and reporting in consideration of the large sums of changes and errors ()PCTs) noted above, and the proximity of the estimated PCTs (and implied oxidation and hydrogen generation) to 10 CFR 50.46(b) PCT limits.

Principal Contributor: Frank Orr Date: March 17, 2006

Donald C. Cook Nuclear Plant, Units 1 and 2 cc:

Regional Administrator, Region III Michigan Department of Environmental U.S. Nuclear Regulatory Commission Quality Suite 210 Waste and Hazardous Materials Div.

2443 Warrenville Road Hazardous Waste & Radiological Lisle, IL 60532-4351 Protection Section Nuclear Facilities Unit Attorney General Constitution Hall, Lower-Level North Department of Attorney General 525 West Allegan Street 525 West Ottawa Street P. O. Box 30241 Lansing, MI 48913 Lansing, MI 48909-7741 Township Supervisor Lawrence J. Weber, Plant Manager Lake Township Hall Indiana Michigan Power Company P.O. Box 818 Nuclear Generation Group Bridgman, MI 49106 One Cook Place Bridgman, MI 49106 U.S. Nuclear Regulatory Commission Resident Inspector's Office Mr. Joseph N. Jensen, Site Vice President 7700 Red Arrow Highway Indiana Michigan Power Company Stevensville, MI 49127 Nuclear Generation Group One Cook Place James M. Petro, Jr., Esquire Bridgman, MI 49106 Indiana Michigan Power Company One Cook Place Bridgman, MI 49106 Mayor, City of Bridgman P.O. Box 366 Bridgman, MI 49106 Special Assistant to the Governor Room 1 - State Capitol Lansing, MI 48909 Mr. John A. Zwolinski Safety Assurance Director Indiana Michigan Power Company Nuclear Generation Group One Cook Place Bridgman, MI 49106