ML17292B130

Application for Amend to License NPF-21,modifying Min Critical Power Ratio Safety Limits by 980515 to Allow Continued Power Operation at WNP-2 Following Restart from R-13 Refueling Outage

ML17292B130
Person / Time
Site:	Columbia
Issue date:	12/04/1997
From:	Bemis P WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML17292B131	List: ML17292B130 ML17292B132
References
GO2-97-219, NUDOCS 9712120362
Download: ML17292B130 (15)

Text

CATEGORY 1 REGUL RY .INFORMATION DISTRIBUT v'YSTEM (RIDS)

P ACCESSION NBR:9712120362 DOC.DATE: 97/12/04 NOTARIZED: YES DOCKET FACIL 50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH 3PAME AUTHOR AFFILIATION BERISI'P.R. Washington Public Power Supply System RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)

SUBJECT:

Application for amend to license NPF-21,modifying min critical power ratio safety limits by 980515-to allow continued power operation at WNP-2 following restart from R-13 refueling outage.

DISTRIBUTION CODE: AOOID COPIES RECEIVED:LTR l ENCL TITLE: OR Submittal: General Distribution SIZE: 7+ Il0 E

NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL PD4-2 LA 1 1 PD4-2 PD 1 1 POSLUSNY,C 1 1 INTERNAL: ACRS 1 1 LE CE ER 1 1 1 NRR/DE/ECGB/A 1 1 1 1 NRR/DRCH/HICB 1 1 NRR/DSSA'/SCSB 1 0 NRR/DSSA/SPLB 1 1 NRR/DSSA/SRXB 1 1 NUDOCS-ABSTRACT 1 1 OGC/HDS3 1 0 EXTERNAL: NOAC 1 1 NRC PDR 1 1 D

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NOTE TO ALL "RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTE. TO HAVE YOUR NAME OR ORGANIZATION REMOVED FROM DISTRIBUTION LISTS OR REDUCE THE NUMBER OF COPIES RECEIVED BY YOU OR YOUR ORGANIZATION, CONTACT THE DOCUMENT CONTROL DESK (DCD) ON EXTENSION 415-2083 TOTAL NUMBER OF COPIES REQUIRED: LTTR 15 ENCL 13

WASHINGTON PUBLIC POWER SUPPLY SYSTEM

,P.O. Box 968 ~ Richland, Washington 99352-0968 December 4, 1997 G02-97-219 Docket No. 50-397 U.S. Nuclear Regulatory Commission,.

Document Control Desk Washington, D.C. 20555 Gentlemen:

Subject:

WNP-2 OPERATING LICENSE NPF-21 REQUEST FOR AMENDMENT MINIMUMCRITICALPOWER RATIO SAFETY LIMITS

References:

1) ~ Critical Power Correlation Uncertainty for Limited Data Sets, ANF-,."

1125(P), Supplement 1, Appendix D, Siemens Power Corporation

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Division, Submitted on April 18, 1997

2) ~ Critical Power Correlation, ANF-1125(P)(A) with Supplements 2, Advanced Nuclear Fuels Corporation, April 1990 1 and

3) Letter KVW:97:115 dated May 20, 1997, KV Walters (Siemens) to RA Vopalensky (Supply System), Revised MCPR Safety Limits for WNP-2 Cycle 11

4) Letter KVW:97:077 dated April 8, 1997, KV Walters (Siemens) to RA Vopalensky (Supply System), "A%% Additive Constant Uncertainties for the SPC 9x9-9X Fuel Design"

5) Letter HDC:97:033 dated April 18, 1997, HD Curet (Siemens) to US NRC Document Control Desk, "Interim Use of Increased ANFB Additive Constant Uncertainty" 97i2i20362 97i204 05000997 PDR ADOCK P

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... REQUEST FOR NT MRIMCMCRITICAL WRR IIATIC SARI TT LMITS Page 2

6) Letter dated July 3, 1997, TG Colburn (NRC) to JV Parrish (Supply System),

"Issuance of Amendment for the Washington Public Power Supply System Nuclear Project No. 2 (TAC No. M98746) (Amendment No. 15 1)"

7) Letter dated November 5, 1997, ABBWP-97-104, Rev. 1, R Matheny (ABB) to RA Vopalensky (Supply System), "WNP-2 Cycle 14 Safety Limit Minimum Critical Power Ratio for SVEA-96 Fuel Based on Reference Core" In accordance with the Code of Federal Regulations, Title 10, Parts 50.59, 50.90, and 2.101, the Supply System hereby submits a request for amendment of the WNP-2 Operating License.

Specifically; the Supply System is requesting modification of the minimum critical power ratio safety limits by May 15, 1998. Approval of the proposed change is necessary to allow continued power operation at WNP-2 following restart &om the R-13 refueling outage.

The proposed change would extend application of the current Cycle 13 Technical Specifications for Siemens Power Corporation (SPC) A'ILIUM-9Xfuel into Cycle 14. The current ATRIUM-9X minimum critical power ratio (MCPR) in Section 2.1.1.2 of 1.13 for two loop operation and 1.14 for single loop operation (Reference 3) would be applied in Cycle 14 as well. This fuel is co-resident with Asea Brown Boveri (ABB) fuel at WNP-2. The ABB fuel MCPR safety limit for two loop operation (1.07) is unchanged. The ABB fuel MCPR safety limit for single loop operation is increased from 1.08 to 1.09 (Reference 7) for Cycle 14.

SPC notified the Supply System (Reference 4) and other users of the A'IRIUM-9 fuel design that a change was necessary in the previously approved method used by SPC to determine the additive constant uncertainty (Reference 2). This change affects the MCPR safety limits for the ATRIUM-9 fuel used at WNP-2 (Reference 3). The proposed amendment requests NRC approval for the continued use of the same interim safety limits for the ATIUUM-9 fuel in Cycle 14 that were previously established (Reference 5) and approved (Reference 6) for Cycle 13. Continued use of the interim values is being requested because the revised methodology submitted by SPC (Reference 1) has not been approved by the NRC. Following NRC approval of the SPC method, another license amendment is anticipated to revise the interim MCPR safety limits.

Additional information has been attached to this letter to complete the Supply System's amendment request. Attachment 1 provides a detailed description of the proposed changes. Attachment 2 summarizes the proposed changes and provides marked up pages of the Technical Specifications.

Attachment 3 describes an evaluation of the proposed changes in accordance with 10CFR50.92(c) and concludes they do not result in a significant hazards consideration. Attachment 4 provides the

, Environmental Assessment Applicability Review and notes that the proposed change meets the eligibility criteria for a categorical exclusion as,set forth in 10CFR51.22(c)(9). Therefore, in accordance with 10CFR51.22(b), an environmental assessment of the change is not required.

Attachment 5 submits the typed Technical Specification pages as they would be revised by this amendment.

This request for an amendment has been reviewed and approved by the WNP-2 Plant Operations Committee and the Supply System Corporate Nuclear Safety Review Board. In accordance with 10CFR50.91, the state of Washington has been provided a copy of this letter.

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illBlhHMCRITICA WER RATIO SAFETY LIMITS Page 3 Should you have any questions or desire additional information regarding this matter, please contact me 'or P. J. Inserra at (509) 377-4147.

Respectfully, Vice President, Nuclear Operations Mail Drop PE23 Attachments:

1. Description of the Proposed Change

2. Marked up Technical Specification Pages

3. Evaluation of Significant Hazards Considerations

4. Environmental Assessment ApplicabilityReview

5. Revised Technical Specification Pages EW Merschofr- NRC RIV KE Perkins, Jr. - NRC MV, Walnut Creek Field Office TG Colburn - NRR C Poslusny, Jr. - NRR NRC Sr. Resident Inspector - 927N DI. Williams - BPA/399 CR Wallis - EFSEC PD Robinson - Winston & Strawn

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STATE OF WASHINGTON )

Subject:

Request for Amendment Minimum s ~

) ri ical Power R ti Safet Limi COUNTY OF BENTON )

I, G. O. SMITH, being duly sworn, subscribe to and say that I am the Acting, Vice President, Nuclear Operations for the WASHINGTON PUBLIC POWER SUPPLY SYSTEM, the applicant herein; that I have the full authority to execute this oath; that I have reviewed the foregoing; and that to the best of my knowledge, information, and belief the statements made in it are true.

DATE J , 1997 G. O. Smith Acting, Vice President, Nuclear Operations On this date personally appeared before me G.O. Smith, to me known to be the individual who executed the foregoing instrument, and acknowledged that he signed the same as his free act and deed for the uses and purposes herein mentioned.

GIVEN under my hand and seal this ~eef day of 1997 f

Notary Public m and r the STATE OF WASHINGTON Residing at My Commission Expires

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SRRRIIM CIIITICAL WRR RATIO SASRTY LOOTS Attachment 1, Page 1 of 3 Description of the Proposed Changes

1. Summary of the Proposed Changes The current licensing analysis projects Cycle 14 will be comprised of 124 &esh ABB assemblies, 112 once-burned ABB assemblies, 104 twice-burned ABB assemblies, and 424 of the at least thrice-burned SPC ATRIUM-9Xassemblies. The NRC approved methodology (i.e., COLR Reference 11: CENPD-300-P-A) assumes that the safety limit MCPR (SLMCPR) for the non-ABB resident fuel is unchanged Rom the last cycle for which it was evaluated by its, supplier. The ATRIUM-9Xfuel was last evaluated by SPC in Cycle 11. Accordingly, a new ATRIUM-9XSLMCPR for Cycle 11 has been determined by SPC (Reference 3) using the, changes to the additive constant uncertainty discussed below. The SPC determined SLMCPR was applied by ABB to Cycle 14 and will be applied to future cycles that the ATRIUM-9Xfuel.

'se A license amendment is being requested to:

~ continue the use of the existing SPC MCPR safety limits (Technical Specifications Section 2.1.1.2) in Cycle 14 that were previously approved for Cycle 13; and

~ to change the ABB MCPR safety limit for single loop operation from 1.08 for Cycle 13 to 1.09 for Cycle 14.

ABB has calculated single loop SLMCPR results that are about 0.006 greater for Cycle 14 than they were for Cycle 13 (Reference 7). The higher Cycle 14 results are due to an assembly radial power distribution used for the Cycle 14 calculations which places a slightly greater number of assemblies close to the peak assembly power than for the Cycle 13 calculations. The increase in ABB single loop MCPR safety limit is attributed to a slightly more conservative assembly power distribution used in the Cycle 14 calculations following ABB standard methodology. While the Cycle 13 result is also conservative, the increase in Cycle 14 is intended to accommodate small cycle to cycle variability.

Continued use of the MCPR safety limit increase on ATRIUM-9Xfuel during Cycle 14 is due to a new additive constant uncertainty calculated and conservatively applied by SPC to the ATRIUM-9Xfuel.

This new ATRIUM-9Xadditive constant uncertainty is necessmy because SPC has determined that the original data base (82 points) used to determine the ATRIUM-9Xadditive constant uncertainty should be expanded to include a wider range of test conditions (Reference 4). In response to this need for additional data points, SPC compiled a larger set of data for the recalculation of the additive constant uncertainty. Data sets &om fuel designs which, like ATRIUM-9X, have full length rods, 9x9 design, and inner water channels were included in the statistical analysis to provide a data pool of 527 points at diferent pressures and Qows. The revised methodology for treating the uncertainties has been submitted to the NRC for approval (Reference 1).

Until the new SPC methodology is approved by the NRC (Reference 1), an interim approach will be used that provides additional conservatism in the calculation of the MCPR safety limit consistent with Reference 5. Reference 5 established a conservative additive constant uncertainty using the di6erence calculated between the additive constant uncertainties for the ATRIUM-9B before and after the data set was expanded Rom 125 to 527 points. This difference was then conservatively doubled and added

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MRIMIIMCRITICA WERIIATIOEAEETTLMITE Attacbment 1, Page 2 of 3 to the original additive constant uncertainty (based on the 125 point data set) to establish a new interim value. This interim value can be applied to the ATRIUM-9X fuel because the expanded data set covers both the ATRIUM-9Band ATRIUM-9Xfuel designs.

This conservative interim additive constant uncertainty was then used by SPC in conjunction with their original NRC approved methodology (Reference 2) to determine the appropriate MCPR safety limit for the ATRIUM-9Xfuel in WNP-2 Cycle 11 (the ATRIUM-9X design was the lead fuel in that cycle). Accordingly, the interim MCPR safety limits for the ATRIUM-9Xfuel have been determined by SPC to be 1.13 for two loop operation and 1.14 for single loop operation, (Reference 3).

The Supply System believes that this conservative approach for calculating the interim MCPR safety limit will continue to ensure design basis fuel protection while Reference 1. is under NRC stafF review.

Using NRC'approved methodology, ABB applied these interim values as the basis for the Cycle 14 safety limit for the co-resident ATRIUM-9X.

After NRC approval. of Reference 1, another license amendment is anticipated to change gower) the, ATRIUM-9XMCPR safety limitto a value supported by, the new NRC approved methodology (based on the revised data base).

2. Detailed Description of the Proposed Safety LimitChanges A) Siemens Power Corporation (SPC)

Just as in Cycle 13, WNP-2 will use Siemens Power Corporation (SPC) ATRIUM-9Xfuel assemblies in Cycle 14 operation. SPC has determined that the need existed to increase the size of the data base for determining the additive constant uncertainty for SPC's ATRIUM-9Xfuel designs with an internal water channel (Reference 4). SPC calculated a new additive constant uncertainty (ACU) for the ATRIUM-.9Xfuel by including additional experimental data fiom critical power tests for other fuel designs which share many of the same design features as the ATRIUM-9Xdesign. The information was selected to address the full operating range of the fuel. Reference 1 details the statistical analysis performed on the data.

SPC increased its ATRIUM-9Xand ATRIUM-9B critical power test data base &om 82 and 125 data points, respectively, to 527 data points that cover a much wider range of pressures, mass cruxes and axial power shapes. The Experimental Critical Power Ratio (ECPR) and the standard deviation of the ECPR for each of the 527 data points were statistically examined by an Analysis of Variance. The results of the Analysis of Variance for each of the pressures are a mean ECPR, a standard deviation of ECPR, degrees of &eedom, and equivalent sample size (Reference 1).

The overall uncertainty for CPR is statistically calculated using the standard deviation of the pooled data and the variance between the means associated with the axial power shapes. An upper 95/o confidence limit standard deviation is calculated based on Chi-Square for the calculated degrees of fi'eedom. The overall standard deviation in ECPR is converted to an ACU. The conversion is derived

&om the ratios of the ANFB correlation standard deviation to the additive constant standard deviation for the ATRIUM-9X data. This calculation is explained in detail in Reference 1 and summarized below:

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RRRMIM CRITICA WAR IAATICSASRTT CMITS Attachment 1, Page 3 of 3 Overall Standard Deviation = 0.0388 (Reference 1)

ECPR to ACU Ratio = 1.99 (Reference 1)

ACU for ATRIUM-9X(data set of 527 points) = 0.0388  : 1.99 = 0.0195 For additional conservatism, this calculated additive constant uncertainty is not directly applied to the MCPR safety limit calculation. Rather, a conservative additive constant uncertainty is used to calculate a new ATRIUM-9XMCPR safety limit for WNP-2 Cycle 11.

Utilizing the ATRIUM-9B design as the basis, the difference is calculated between the additive constant"uncertainties after and prior to the data=set being expanded to include 527 points. This difference is then conservatively doubled. The doubled difference in the additive constant uncertainties is then adde'd tothe additive constant uncertainty prior to the expansion of the'data set (based on 125 data points). This calculation is summarized below:

Additive Constant Uncertainty for ATIGUM-9B (data set of 125 points) = 0.010 Additive Constant Uncertainty for ATRIUM-9B (data set of 527 points) = 0.0195 Calculation of the interim Additive Constant Uncertainty for the ATRIUM-9B=

(0.010+ 2(0.0195-0.010)) = 0.029 The resulting conservative additive constant uncertainty of 0.029 for ATRIUM-9B was then applied to the ATRIUM-9Xfuel and was used to calculate the interim MCPR safety limits of 1.13 (two loop operation) and 1.14 (single loop operation) for ATRIUM-9Xfuel for WNP-2 Cycle 11 (Reference 3).

Using NRC approved ABB methodology, these MCPR safety limit values apply for future cycles for the ATRlUM-9Xfuel.

After NRC approval of Reference 1, an additional license amendment is anticipated to change gower) the MCPR safety limit for the ATRIUM-9X fuel based on the application of the newly approved methodology.

B) Asea Brown Boveri (ABB)

ABB has completed an evaluation of the cycle dependent SVEA-96 Safety Limit Minimum Critical Power Ratio (SLMCPR) for WNP-2 Cycle 14 (Reference 7). The Cycle 14 SLMCPR of 1.07 for two loop operation remains unchanged from Cycle 13. The SLMCPR for single loop operation has been determined to be 1.09 for Cycle 14. The calculated single loop SLMCPR results are about 0.006 greater for Cycle 14 than they were for Cycle 13. The higher Cycle 14 results are due to an assembly radial power distribution used for the Cycle 14 calculations which places a slightly greater number of assemblies close to the peak assembly power than for the Cycle 13 calculations. The increase in single loop MCPR safety limit is attributed to a slightly more conservative assembly power distribution used in the Cycle 14 calculations following ABB standard methodology. While the Cycle 13 result is also conservative, the increase in Cycle 14 is intended to accommodate small cycle to cycle variability.

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