ML17292A863

Application for Amend to License NPF-21,requesting Mod of Minimum Critical Power Ratio Safety Limits by 970615

ML17292A863
Person / Time
Site:	Columbia
Issue date:	05/20/1997
From:	Bemis P WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML17292A864	List: ML17292A863 ML17292A865
References
GO2-97-102, NUDOCS 9705280115
Download: ML17292A863 (11)

Text

CATEGORY 1 cz,- REGULATG INFORMATION DISTRIBUTION ..SYSTEM (RIDS)

ACCESSION NBR:9705280115 DOC.DATE: 97/05/20 NOTARIZED: YES DOCKET FACIL:50-397 WPPSS Nuclear Project, Unit 2, Washington Public Powe 05000397 AUTH. NAME AUTHOR AFFILIATION BEMIS,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,requesting mod of minimum critical power ratio safety limits by 970615.

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TITLE: OR Submittal: General Distribution NOTES:

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WASHINGTON PUBLIC POWER SUPPLY SYSTEM P.O. Box 968 ~ Richlnttd, Wnshington 99352-0968 May 20, 1997 G02-97-102 Docket No. 50-397 U.S. Nuclear Regulatory Commission Document Control Desk Washington, D.C. 20555 Gentlemen:

Subject:

WNP-2 OPERATING LICENSE NPF-21 EXIGENT REQUEST FOR AMXNDMIi22lT MINIMVI'8CRITICALPOWER RATIO SAFETY LIMITS

References:

1) ANFB Critical Power Correlation Uncertainty for Limited Data Sets, ANF-1125(P), Supplement 1, Appendix D, Siemens Power Corporation - Nuclear Division, Submitted on April 18, 1997. 'i F

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

3) Letter KVW:97:115 dated May 20, 1997, KV Walters (Siemens) to RA Volpalensky (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), ANFB 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.

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, under exigent circumstances, to the WNP-2 Operating License. Specifically, the Supply System is requesting modification of the minimum critical power ratio safety limits by June 15, 1997.

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OPERATING LICENSE AMENDMENTREQUEST MIRIMIMCRITICAL SOWER TATI R S ARTTT LMITS Page 2 The proposed change would modify the Technical Specifications for minimum critical power ratio (MCPR) in Section 2.1.1.2 by specifying new safety limits for the operation of Siemens Power Corporation (SPC) ATRIUM-9X fuel of 1.13 for two loop operation and 1.14 for single loop operation (Reference 3). This fuel is coresident with Asea Brown Boveri (ABB) fuel at WNP-2.

The ABB fuel MCPR safety limitis unchanged.

SPC recently notified the Supply System (Reference 4) and other users of the ATRIUM-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 amendment request is necessary because the change has resulted in revised MCPR safety limits for WNP-2 (Reference 3). The requested change will set conservative interim safety limits for the ATRIUM-9X fuel to allow continued power operation at WNP-2 (Reference 5). An interim value has been requested because the revised methodology submitted by SPC (Reference 1) has not yet been approved by the NRC, Following NRC approval, another license amendment is anticipated to revise the interim MCPR safety limits.

Approval of the proposed amendment on an exigent basis is warranted due to the short time between when SPC provided the Supply System with plant specific information needed to make this request (May 20, 1997; Reference 3) and when WNP-2 Cycle 13 is scheduled to start (June 15, 1997). This short time interval will not allow for the normal 30 day period for public comment.

This condition was unavoidable and not created by the failure to make a timely application for a Technical Specification amendment. Without approval of this exigent amendment, WNP-2 will be unable to resume power operation.

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 the marked up pages of the Technical Specifications. Attachment 3 describes an evaluation of the proposed changes in accordance with 10CFR50.92(c) and concludes that it does not result in a significant hazards consideration. 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 amendent request.

This request for an exigent 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.

OPERATING LICENS AMENDMENTREQUEST MSSMIIM CIIIPICALPAW SS ILIPIC S APSPP LINISS Page 3 Should you have any questions or desire additional information regarding this matter, please contact me or D.A.- Swank at (509) 377-4563.

Respectfully, P.. Be 's V'ce President Nuclear Operations Mail Drop PE23 Attachments:

1. Description of the Proposed Change

2. Revised Technical Specifications

3. Evaluation of Significant Hazards Considerations

4. Environmental Assessment Applicability Review

5. Revised Technical Specification Pages CC: EW Merschoff - NRC RIV KE Perkins, Jr. - NRC RlV, Walnut Creek Field Office TG Colburn - NRR NRC Sr. Resident Inspector - 927N DL Williams - BPA/399 CR Wallis - EFSEC PD Robinson - Winston & Strawn

1 STATE OF WASHINGTON ) Subject; Request for Amendment to TS

) M PR afe Limi COUNTY OF BENTON )

I, P. R. BEMIS, being duly sworn, subscribe to and say that I am the Vice President, Nuclear Operations for the WASHINGTONPUBLIC POWER SUPPLY SYSTEM, the applicant herein; I

that 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 , 1997 P.R B Vice President, Nuclear Operations On this date personally appeared before me P. R. BEMIS, 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 CgQ day of 1997.

Public in and for the STATE OF WASHINGTON s

Jrg Jg Residing at C

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MINIINU16CRITICALPOWER RATIO SAFETY LIMITS e , Page 1 Attachment 1 Description of the Proposed Changes

1. Summary of the Proposed Changes The MCPR safety limit increase on ATRIUM-9Xfuel is due to a new additive constant uncertainty calculated and conservatively applied by SPC to the ATRIUM-9Xfuel. This new ATIUUM-9X additive constant uncertainty is necessary 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 from 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 different pressures and flows. 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 difference calculated between the additive constant uncertainties for the ATRIUM-9B before and aAer the data set was expanded from 125 to 527 points. This difference was then conservatively doubled and added 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-9Xfuel because the expanded data set covers both the ATRIUM-9Band ATRIUM-9Xfuel designs.

This new 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-9Xdesign was the lead fuel in that cycle). Accordingly, the new interim MCPR safety limits for the ATRIUM-9X fuel have been determined by SPC to be 1. 13 for two loop operation and 1. 14 for single loop operation (Reference 3). A license amendment is being requested because these values are greater than the existing MCPR safety limits (Technical Specifications Section 2.1.1.2) and a revision is therefore necessary to incorporate a fuel specific limit. The list of analytical methods (Technical Specifications 5.6.5) used to determine the core operating limits has also been changed to incorporate the methodology used to establish the interim value for the additive constant uncertainty (Reference 5).

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 has utilized these interim values as the basis for the Cycle 13 safety limit for the coresident ATRIUM-9Xfuel.

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OPERATING LICEN~MENDMENTREQUEST MINIMUMCRITICALPOWER RATIO SAFETY LIMITS

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Attachment 1, Page 2 After NRC approval of Reference 1, another license amendment is anticipated to change gower) the ATRIUM-9XMCPR safety limit to a value supported by the new NRC approved methodology (based on the revised data base).

2. Detailed Description of the Proposed Safety Limit Changes WNP-2 will be using Siemens Power Corporation (SPC) ATRIUM-9Xfuel assemblies in Cycle 13 operation. SPC has determined that the need exists 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 has calculated a new additive constant uncertainty for the ATRIUM-9Xfuel by including additional experimental data from critical power tests for other fuel designs which share many of the same design features as the ATRIUM-9X design. 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 from 82 and 125 data points, respectively, to 527 data points that cover a much wider range of pressures, mass fluxes 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 freedom, 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%

confidence limit standard deviation is calculated based on Chi-Square for the calculated degrees of freedom. The overall standard deviation in ECPR is converted to an additive constant uncertainty (ACU). The conversion is derived from the ratios of the ANFB correlation standard deviation to the additive constant standard deviation for the ATRIUM-9Xdata. This calculation is explained in detail in Reference 1 and summarized below:

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 added to the additive constant uncertainty prior to the expansion of the data set (based on 125 data points). This calculation is summarized below;

II N OPERATING LICEN~MENDMENTREQUEST MINIMUMCRITICALPOWER RATIO SAFETY LIMITS e

~ Attachment 1, Page 3 Additive Constant Uncertainty for ATRIUM-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 is then applied to the ATRIUM-9Xfuel and is used to calculate the new interim MCPR safety limits of 1. 13 (two loop operation) and 1.14 (single loop operation) for ATRIUM-9X fuel for WNP-2 Cycle 11 (Reference 3). Using NRC approved ABB methodology, these MCPR safety limit values will apply for future cycles for the ATRIUM-9Xfuel.

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