ML20198G023

Forwards Suppl 9 to CENPD-279, Annual Rept on ABB CE ECCS Performance Evaluation Models, as Required by 10CFR50.46

ML20198G023
Person / Time
Site:	San Onofre
Issue date:	12/22/1998
From:	Scherer A SOUTHERN CALIFORNIA EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9812280277
Download: ML20198G023 (4)

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December 22, 1998 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555 Gentlemen:

Subject:

Docket Nos. 50-361 and 50-362 1997 Emergency Core Cooling System Annual 10 CFR 50.46 Report San Onofre Nuclear Generating Station, Units 2 and 3

References:

1.

June 2,1998 letter from J. L. Rainsberry (SCE) to Document Control Desk (NRC),

Subject:

Docket Numbers 50-361 and 50-362, ABB-CE LOCA Evaluation Model, San Onofre Nuclear Generating Station, Units 2 and 3 2.

October 22, 1998 letter from Robert S. Bell, Jr. (ABB CE) to Annette Gilliam (SCE),

Subject:

Limited Authorization to Reproduce a Copyrighted Document This letter transmits as Enclosures 1 and'2 the San Onofre Units 2 and 3 annual report for the 1997 calendar year required by paragraph (a)(3)(ii) of 10 CFR 50.46, " Acceptance criteria for emergency core cooling systems for light-water nuclear power reactors." This regulation requires Southern California Edison (SCE) to annually report to the NRC for San Onofre Units 2 and 3 the nature of each change to or error discovered in the Emergency Core Cooling System (ECCS) evaluation model or in the application of this model that affects the temperature calculation and estimated effects of any such changes, errors, or applications on the limiting ECCS analysis. Any significant change or error is required to be reported to the NRC within 30 days.

For the 1997 reporting period, Asea Brown Boveri Combustion Engineering (ABB CE), who performed the ECCS calculations for San Onofre Units 2 and 3, discovered the following four sets of reportable changes or errors in the evaluation models or application of the models:

9812280277 981222

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PDR ADOCK 05000361 P

PM P. O. Box 128 l

San Clemente, CA 92674 0128 949-368-7501 rax 949-368-7575

Document Control Desk.

1.

The computer codes for ECCS performance analysis were converted to operate on Hewlett Packard workstations, 2.

Implementation of the methodology for small break Loss of Coolant Analysis (LOCA) ECCS performance aralysis was changed, 3.

An error in the calculation of the boric acid concentration for both the large and small break LOCA was found and corrected, and 4.

An error in the decay heat energy redistributrion factor used for large break LOCA ECCS performance analysis, which could lead to an underprediction of peak cladding temperature (PCT), was found and corrected.

"The Annual Report on ABB CE ECCS Performance Evaluation Models, CENPD-279 Supplement 9" (Enclosure 1) describes the above changes and errors in the ABB CE codes and methodology for the San Onofre Units 2 and 3 ECCS analysis for the 1997 reporting period.

CENPD-279 Supplement 9 Appendix C summarizes the 1997 ABB CE and SCE to NRC correspondence associhted with the error in the energy redistribution factor for San Onofre. Appendices A, B, D, and E of CENPD-279 Supplement 9 describe the energy redistribution factor error for plants other than San Onofre, and are therefore not included.

Subsequent to the ABB CE issuance of the CENPD, a June 2, 1998 letter from SCE to the NRC (Reference 1) was also submitted on this topic to make editorial corrections to one of the 1997 submittals.

For the 1997 reporting period, a 40*F error was found in the large break LOCA calculation. No changes or errors which impact the peak clad temperature were found in the evaluation models or application of the models for the small break LOCA or post-LOCA long term cooling calculations.

SCE made no changes to the LOCA evaluation models per 10 CFR 50.59. provides a summary of the effect on PCT of the errors or changes to the ECCS evaluation model reported under 10 CFR 50.46 for 1997.

The arithmetic sum of the PCT effects of both the 10 CFR 50.46 and 10 CFR 50.59 changes is a 40*F effect on the large break LOCA analysis PCT.

In 1997 the limiting large break LOCA PCT did not exceed the 10 CFR 50.46(b)(1) acceptance criterion of 2200*F.

Document Control Desk.

The sum of the absolute magnitude of the 10 CFR 50.46 evaluation model changes and errors found since the approval of the August 1994 large break LOCA analysis is 40*F.

An October 22, 1998 ABB CE letter (Reference 2) providing limited authorization for the NRC to reproduce the copyrighted CENPD-279 Supplement 9 (Enclosure 1) is provided as Enclosure 3.

If you have any questions or need additional information on this subject, please let me know.

Sincerely, Enclosures cc:

E. W. Merschoff, Regional Administrator, NRC Region IV J. A. Sloan, NRC Senior Resident Inspector, San Onofre Units 2 & 3 J. W. Clifford, NRC Project Manager, San Onofre Units 2 and 3

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l ENCLOSURE 1 ANNUAL REPORT ON ABB CE ECCS '

l-PERFORMANCE EVALUATION MODELS l

CENPD-279 SUPPLEMENT 9 1

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COMBUSTION ENGINEERING OWNERS GROUP CENPD-279 SUPPLEMENT 9 ANNUAL REPORT ON ABB CE ECCS i

PERFORMANCE EVALUATION MODELS I

FINAL REPORT CEOG TASK 1024 prepared for the C-E OWNERS GROUP March 1998 8 Copynght 1998 Combustion Engmeering, Inc. All rights reserved ABB Combustion Engineering Nuclear Operations ESEEEE

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LEGAL NOTICE This report was prepared as an account ofwork sponsored by the Combustion Engineering Owners Group and ABB Combustion Engineering. Neither Combustion Engineering, Inc. nor any person acting on its behalf:

A.

makes any warranty or representation, express or implied including the warranties of fitness for a particular purpose or merchantability, with respect to the accuracy, completeness, or usefulness of the information contained in this report, or that the use of any information, apparatus, method, or process disclosed in this report may not infringe privately owned rights; or B.

assumes any liabilities with respect to the use of, or for damages resulting from the use of, any information, apparatus, method or process disclosed in this report.

Combustion Engineering, Inc.

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ABSTRACT This report describes changes and errors in the ABB Combustion Engineering evaluation models for ECCS performance analysis in 1997 per the requirements of 10CFR50.46. For this reporting period, there were four sets of reportable changes or errors in the evaluation models or application of the models:

1. All of the ECCS performance analysis codes were converted to HP workstations operating under the HP/UX operating system. This had no effect on the peak cladding temperature (PCT).

2. A change in the implementation of the methodology for small break LOCA (SBLOCA) ECCS performance analysis was made to improve the analysis process i

which would introduce a 3 F cumulative change in PCT for SBLOCA when the new process is used for the analysis of record.

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3. An error in the implementation of the boric acid concentration calculation with flushing flow for both large and small break LOCA was found and corrected. This affected the post-LOCA boric acid concentration but is unlikely to affect the time to initiate combined hot-side / cold-side injection for LBLOCA. It had no effect on the boric acid precipitation conclusions for SBLOCA. Hence, there is no effect on core coolability or PCT.

4. An error in the decay heat energy redistribution factor used for large break LOCA ECCS performance analysis was found and corrected.. This required compensatory action such as a reduction in the maximum linear heat generation rate, a reduction in the pin-to-box factor margin, or other action to maintain the applicability of the analyses of record and meet the ECCS acceptance criteria.

The following summary describes the generic status of the ABB CE ECCS performance analysis methodology. The sum of the absolute magnitude of the PCT changes for large break LOCA from all reports to date, except for the effect of the decay heat energy redistribution factor (ERF) error, continues to be less than 1 F. The effect of the ERF error is plant specific so the total LBLOCA PCT impact for each plant is the sum of 1 F and the plant specific contribution given in Appendices A through E. The sum of the absolute magnitude of the maximum cladding temperature changes for small break LOCA from all reports to date is less than 3 F. No change occurred in the PCT for post-LOCA long term cooling. Per the criteria of 10CFR50.46, no action beyond this annual report is required for the generic results.

The impact of the error in the ERF for large break LOCA is plant specific. The nature of the error, how it was resolved, and an approximation of the impact of the error on PCT is provided in Appendices A through E.

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TABLE OF CONTENTS Section Iit]s Eagg

1.0 INTRODUCTION

1 1

2.0 ~

ABB CE CODES USED FOR ECCS EVALUATION 3

3.0 EVALUATION MODEL CHANGES AND ERROR CORRECTIONS 4

4 3.1 Code Conversion 3.2 Automation of Data Transfer for Small Break LOCA Analysis 3.3 -

Post-LOCA Bonc Acid Concentration 3.4 Decay Heat Energy Redistribution Factor Error

4.0 CONCLUSION

S 11

5.0 REFERENCES

12 APPENDICES A.

ARIZONA PUBLIC SERVICE COMPANY (PVNGS Units 1-3) l B.

BALTIMORE GAS AND ELECTRIC COMPANY (Calvert Cliffs Units 1 & 2)

C.

SOUTHERN CALIFORNIA EDISON COMPANY (SONGS Units 2 & 3)

D.

FLORIDA POWER AND LIGHT COMPANY (St. Lucie Unit 2)

E.

ENTERGY OPERATIONS INCORPORATED 1.

Arkansas Nuclear One Unit 2

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Waterford Unit 3 i

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1.0.

INTRODUCTION This repon addresses the NRC requirement to report changes or errors in ECCS performance evaluation models. The ECCS Acceptance Criteria, Reference 1, spells out reporting requirements and actions required when errors are corrected or changes are made in an evaluation model or in the application of a model for an operating licensee or construction permittee of a nuclear power plant.

The action requirements in 10CFR50.46(a)(3) are:

1.

Each applicant for or holder of an operating license or construction permit shall estimate the effect of any change to or error in an acceptable evaluation model or in the application of such a model to determine if the change or error is significant.

For this purpose, a significant change or error is one which results in a calculated peak fuel cladding temperature (PCT) different by more than 50*F 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'F.

2.

For each change to or error discovered in an acceptable evaluation model or in the application of such a model that affects the temperature calculation, the applicant or licensee shall report the nature of the change or error and its estimated effect on the limiting ECCS analysis to the Commission at least annually as specified in 10CFR50.4.

3.

If the change or error is significant, the applicant or licensee shall provide this -

repon 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 10CFR50.46 requirements. This schedule may be developed using an integrated scheduling system previously approved for the facility by the NRC. For those facilities not using an NRC approved integrated scheduling system, a schedule will be established by the NRC staff within 60 days of receipt of the proposed schedule.

4.

Any change or error correction that results in a calculated ECCS performance that does not conform to the criteria set forth in paragraph (b) of 10CFR50.46 is a reportable event as described in 10CFR50.55(e),50.72 and 50.73. The affected applicant or licensee shall propose immediate steps to demonstrate compliance or bring plant design or operation into compliance with 10CFR50.46 requirements.

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i This feport documents all the errors corrected in and/or changes to the presently license i

CE ECCS performance evaluation models, made in the year covered by this report, which have not been nyiewed by the NRC staff. This document is provided to satisfy the reporting requirements of the second item above. ABB CE reports for earlier years are given in References 2.t 0.

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2.0 ABB CE CODES USED FOR ECCS EVALUATION ABB CE uses several digital computer codes for ECCS performance analysis that are described in topical repons, are licensed by the NRC, and are covered by the provisions of 10CFR50.46.

Thosis for large break LOCA calculations are CEFLASH-4A, COMPERC-II, HCROSS, PARCH, STRIKIN-II, and COMZIRC. CEFLASH-4AS is used in conjunction with COMPERC-II, STRIKIN-II, and PARCH for small break LOCA calculations. The codes for post-LOCA long term cooling analysis are BORON, CEPAC, NATFLOW, and CELDA.

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3.0 EVALUATION MODEL CHANGES AND ERROR CORRECTIONS This section discusses all error corrections and model changes to the ABB CE ECCS perfonnance evaluation models which may affect the calculated PCT.

i 3.1 Code Conversion All of the NRC licensed codes and related utility programs used for ECCS performance analysis were converted from operation on Hewlett Packard (HP) Apollo workstations (WS) operating under the Domain operating system (OS) to HP WS operating under the HP/UX operating system. The coding changes to maintain numeric precision and comply with FORTIRN programmmg conventions described in the 1992 code conversion, Reference 6, were preserved.

A few changes to the FORTRAN coding were necessary to accommodate differences in FORTRAN compiler implementations and replace non-standard coding with standard coding.

Some new edits were added to facilitate use of the codes. The code version numbers and implementation dates were adjusted to maintain unique identification of the new code versions.

Except for one new procedure for small break LOCA described in Section 3.2, no changes were made to the models or their implementation.

The same procedures used to validate the converted codes in the 1992 conversion, Reference 6, were used in this conversion. Direct comparison of all results from runs on the HP Apollo computers with those from the new HP computers were made with an acceptance criterion of 0.01% when feasible. For some codes, such as those that compute their own time step lengths, a direct comparison of all output is not possible due to differences in the times at which results are reported. In such cases, comparison of key parameters passed on to subsequent steps in the analysis, objective parameters such as PCT and peak cladding oxidation, or graphical comparison of the time history ofimportant parameters are used to validate the converted codes.

3.1.1 Large Break LOCA The only changes made to the ECCS performance analysis codes used for large break LOCA (LBLOCA) analysis are those required to make them function on the new computers, add new edits, and provide unique version identification. No changes to the models used for large break LOCA analysis or their implementation were made. The overall impact of the conversion was no change in PCT to the precision of the printed results, <0.01 F.

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i 3,1.2 Small Break LOCA One change was made to the ECCS performance analysis codes used for small break LOCA (SBLOCA) analysis beyond those required to make them function on the new computers, add new edits, and provide unique version identification. That change and its impact on peak cladding temperature, including the impact of code conversion is discussed in Section 3.2.

3.1.3 Post-LOCA Long Term Cooling The only changes made to the ECCS performance analysis codes used for post-LOCA long term cooling analysis are those required to make them function on the new computers, add new edits, and provide unique version identification. No changes to the models or their implementation were made. The overall impact of t.he conversion was no signi6 cant change to any result. Hence, there was no effect on peak cladding temperature due to conversion of the post-LOCA long term cooling codes.

3.2.

Automation ofData Transfer for Small Break LOCA Analysis As part of the code conversion process, one change was made to the ECCS performance analysis codes used for SBLOCA analysis beyond those required to make them function on the new computers, add new edits, and provide unique version identification. An option was added to transfer the core boundary conditions camputed by the CEFLASH-4AS blowdown hydraulics

. computer code to the hot rod heatup code PARCH via a file created by CEFLASH-4AS and read

. by PARCH. Previously, the procedure had been to manually transfer up to 50 values ofeach boundary condition from CEFLASH-4AS to PARCH. These two codes were revised to transfer 2000 evenly spaced values in time during the transient for core pressure, coolant mixture level, coolant mass, and power from CEFLASH-4AS to PARCH in a disk file. The revised process for

' data transfer provides a more accurate and efficient method of transferring the data. In a sample calculation, this change produced a 2.4*F reduction in maximum cladding temperature during the transient.

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3.3 Post-LOCA Boric Acid Concentration An error in the calculation of the boric acid concentration for post-LOCA long term cooling was found in the BORON code for LBLOCA and in the CELDA code for SBLOCA. The error affects the boric acid concentration in the reactor core and the sump when the hot side injection flow rate exceeds the boil-offrate in the core. It does not affect the results before recirculation between the sump and reactor vessel as described below.

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, Once recirculation between the sump and reactor vessel begins, after the boric acid storage or makeup tanks (B ASTs) and refueling water tank (RWT) empty, the BORON code calculates the boric acid concentration in the reactor vessel and sump from the following differential equations

p. C-10 in Reference 11:

4 dBeca/dt

-= (Won x Bstw.Ws x Bcon) / Va dB w/dt

= (Ws x Bcom - Wow x 3stw) / Vson -

3t where Bcon boric acid concentration in core (wt%)

Bsta boric acid concentration in sump (wt%)

Va volume ofliquid water in reactor vessel (gallons)

Vson volume ofwaterin sump (gallons)

Wu

. flow rate into sump (gpm)

Won flow rate from sump (gpm)

. The CELDA code finds the boric acid concentrations using the same methodology.

. In the original implementation of the BORON and CELDA codes, the flow rate into the sump and out of the sump were found, respectively, as Wu

= Wausu Won = Wson, where Wson.

- boil-off rate (gpm) -

Wausa flushing flow rate (gpm)

~ The flow rate out of the sump into the core should include the flushing flow rate as well as the boil-off rate or i

Won = Weon. + Wn.csa This change was implemented in the BORON and CELDA codes. The effect of correcting the codes is discussed below.

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i 3.3.1 Effect cfError for LBLOCA Boric Acid Concentration The BORON code finds the boric acid concentration in the core after a LBLOCA. The effect o the error in Wour depends on the timing of hot side injection and the magnitude of the flow. Two examples are used to illustrate this point.

The first example initiates hot side injection with a flow rate sufficient to exceed the boil-off rate at the time hot side injection begins. The boric acid concentration in the core for this case is shown in Figure 1 for the erroneous and corrected calculation. The correction has no effect on the maximum boric acid concentration although it shows a slower rate of decrease than the erroneous implementation of the boric acid concentration model.

The second example initiates hot side injection with a flow rate less than the boil-off rate at the time injection begins. Figure 2 shows that the core boric acid concentration continues to rise until nearly four hours with injection starting at three hours. The corrected maximum boric acid concentration is about 0.22 wt% higher and occurs about one-tenth of an hour later. Consistent with the results of the first example, the rate of decrease is slower with the corrected model.

Results similar to those reported in Figures 1 and 2 art, expected for all post-LOCA boric acid precipitation analyses performed by ABB CE although the magnitude of the results would differ from plant to plant. The effect of the error shown in Figure 2 is small compared to the difference between the maximum calculated boric acid concentration for ABB CE plants and the associated solubility limit.

3.3.2 Effect ofError for SBLOCA Boric Acid Concentration CELDA includes a copy of the BORON coding as a subroutine with revisions to link it to the overall CELDA hydraulics calculation. The BORON subroutine is run at the end of the CELDA calculation to evaluate boric acid concentration using flushing flows calculated by CELDA. The corrected code gives a maximum boric acid concentration about 0.1 wt% higher than the erroneous implementation af the boric acid concentration model. This increase is insignificant in comparison to the margin to the boric acid solubility limit for the SBLOCA boric acid concentration analysis.

3.4 Decay Heat Energy Redistribution Factor Error An error in the decay heat energy redistribution factor (ERF) for voided conditions used in the large break LOCA analysis was discovered and corrected in 1997, References 12 and 13. The ERF is defined as the ratio of the fission energy deposited in the hot fuel rod divided by the 7

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, energy generated in the hot rod. Typical values range from 0.92 to 0.98 depending on the hot rod pin-to-box ratio.

As described in the ABB CE large break LOCA evaluation model topical report (Reference 14) the ERF used in the large break LOCA evaluation model includes the effect of moderator voiding.

Because of fuel design changes made in the 1970s which produced flatter power distributions with the hot rod no longer adjacent to a guide tube, ABB CE calculated new values for the ERF for both fission and decay heat power. Erroneously, the calculations did not include the effect of moderator voiding on,the recalculated values for the decay heat ERFs.

The magnitude of the error in ERF is dependent on the pin-to-box ratio and pin lattice as shown in the table below. A generic approximation of the effect on PCT can be made based on an observed sensitivity of about 40*F in PCT per 1% change in ERF for a typical plant where the limiting PCT occurred during the reflood phase of the event.

14x14 Fuel Assembly 16x16 Fuel Assembly Pin / Box ERF Channe (%)

ERF Channe (%)

1.03 1.3 1.0.

1.10 1.0 0.7 ABB CE Infobulletin 97-04, Reference 12, and its status updates provide additional information regarding the ERF error. A plant specific discussion of the ERF error is given in Appendices A through E.

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Figure 1 Initial Hot-Side Injection Rate Exceeds Boil-off Rate Corrected Version

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4.0 CONCLUSION

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'I All of the codes used in the ABB CE ECCS performance evaluation model were converted to H

.. workstations operating under the HP/UX operating system and one change in the applicatio the evaluation model for SBLOCA occurred in 1997. In addition, two errors were identified --

one for post-LOCA long term cooling and one for LBLOCA.

The change in computers used to run the ABB CE ECCS performance analysis computer codes produced no changes in the PCT for LBLOCA, SBLOCA, or post-LOCA long term cooling.

j Excluding plant specific effects due to the error in ERF, the sum of the absolute magnitude of th changes in PCT calculated using the ABB CE ECCS evaluation models, including those from i

previous annual reports, References 2-10, remains less than l'F for LBLOCA. The total LBLOCA PCT impact for a given plant is 1 F plus the plant specific effect of the ERF error giv in Appendices A through E.

The change in the application of the SBLOCA model combined with the effects from previous annual reports, References 2-10, produce a cumulative change in maximum cladding temperature for SBLOCA ofless than 3'F. This change in the application of the SBLOCA model was not applied to any Analysis ofRecord (AOR)in 1997.

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An error was discovered and corrected in the computer codes that calculate the post-LOCA boric acid concentration in the core. The error has minimal or no impact on the margin between the maximum calculated boric acid concentration for ABB CE plants and the associated solubility limit. Correction of the errorin boric acid concentration has no effect on the PCT.

A generic statement applicable to all plants for the impact of the ERF error on PCT is not possible. The approximate increase in PCT for the lattices and range of pin-to-box ratios repor in the table in Section 3.4 is 28 to 52*F but the results depend on the lattice and the pin-to-box factor. A 0.2 kW/ft reduction in the PLHGR or other compensatory actions could support the existing AOR. Plant specific information about the PCT impact of the error in ERF and the actions taken by each plant licensee to address the error is given in Appendices A through E.

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' REFERENCES 1.

" Acceptance Criteria for Emergency Core Cooling Systems for Light Water Nuclear Power Reactors," Code of Federal Regulations, Title 10, Part 50, Section 50.46.

2.

" Annual Report on C-E ECCS Codes and Methods for 10CFR50.46," CENPD-279, April, 1989.

3.

" Annual Report on C-E ECCS Codes and Methods for 10CFR50.46," CENPD-279, Supplement 1, February,1990.

4.

" Annual Report on C-E ECCS Codes and Methods for 10CFR50.46," CENPD-279, Supplement 2, April,1991.

5.

" Annual Report on C E ECCS Codes and Methods for 10CFR50.46," CENPD-279, i

Supplement 3, April,1997 6.

" Annual Report on C-E ECCS Codes and Methods for 10CFR50.46," CENPD-279, bpplernent 4, April,1993.

7.

" Annual Report on C-E ECCS Codes and Methods for 10CFR50.46," CENPD-279, Supplement 5, February,1994.

8.

" Annual Report on ABB C-E ECCS Performance Evaluation Models," CENPD-279, Supplement 6, February,1995, 9.

" Annual Report on ABB C-E ECCS Performance Evaluation Models," CENPD-279, Supplement 7, February,1996.

t 10.

" Annual Report on ABB C-E ECCS Performance Evaluation Models," CENPD-279, l

Supplement 8, February,1997.

I 11.

" Post-LOCA Long Term Cooling Evaluation Model," CENPD-254-P-A, June 1980.

12.

" Potential Error in the Energy Redistribution Factor Used in LOCA Analysis,"

Combustion Information Bulletin 97-04, Rev. 01, July 11,1997.

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" Report Pursuant to 10CFR21 Regarding Error in the Energy Redistribution Factor Used t

in LOCA Analysis," LD-97-024, August 14,1997.

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" Calculative Methods for the C-E Large Break LOCA Evaluation Model," CENPD.

132P, August 1974.

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4 APPENDIX C SOUTHERN CALIFORNIA EDISON COMPANY Effect of ERF Error on PCT for SONGS Units 2 and 3 Introduction As described in Section 3.4, a non-conservative error in the decay heat energy redistribution factor (ERF) which could lead to an underprediction of peak cladding temperature (PCT) was discovered and corrected. Persuant to the requirements of 10CFR 21, the NRC was notified of the error in the ERF by Reference I which stated that the peak cladding temperature could be underestimated by 20 to 60 F. Licensees using the ABB CE LBLOCA evaluation model were informed that the validity of their analyses of record (AOR) would be maintained provided that the margin to the peak linear heat generation rate (PLHGR) is at least 0.2 kW/ft.

FErc In Rderence 2 SONGS notified the NRC that ABB CE had found that the peak cladding temperature (PCT) increased by less than 50 F for the SONGS 16x16 lattice configuration.

Reference 2 stated that the linear power density penalties already implemented for the current SONGS cycles provided sufficient conservatism to account for the 0.2 kW/ft reduction in PLHGR recommended by ABB CE. It further stated that sufficient margin existed for each presious cycle to ensure that the PCT was maintained below the required 2200 F. Further information about the penalties used for the Core Operating Limit Supervisory System (COLSS) and for the Core Protection Calculator (CPC) was provided in Reference 3. SCE determined that, based on the final ABB CE estimate of a 40*F PCT change, the 10CFR50.46 50 F criterion for a significant change was not violated. SCE further concluded that the PCT with the 40 F ERF error is below 2200 F. The results of this evaluation support final resolution of the ERF error.

Conclusion Sufficient margin exists in the SONGS 2 & 3 LOCA analysis to compensate for the ERF error and assure conformance to the 10CFR50.46 acceptance criteria.

References:

Letter from I. C. Rickard (ABB-CE) to Document Control Desk (USNRC), " Report 1.

Pursuant to 10CFR21 Regarding Error in the Energy Redistribution Factor Used in LOCA Analysis," LD-97-024, August 14,1997.

2.

Letter, R. W. Krieger (SCE) to Document Control Desk (USNRC), " Docket Numbers 50-361 & 50-362, Voluntary Report - ABB-CE LOCA Evaluation Model, San Onofre Nuclear Generating Station, Units 2 & 3," October 9,1997.

3.

Letter, R. W. Krieger (SCE) to Document Control Desk (USNRC), " Docket Numbers 50-361 & 50-362, ABB-CE LOCA Evaluation Model, San Onofre Nuclear Generating Station, Units 2 & 3," November 6,1997.

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I ENCLOSURE 2 LOSS OF COOLANT ACCIDENT (LOCA) MARGIN

SUMMARY

- SAN ONOFRE GENERATING STATION l

UNITS 2 AND 3 i

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LOSS OF COOLANT ACCIDENT (LOCA) MARGIN

SUMMARY

SAN ONOFRE NUCLEAR GENERATING STATION UNITS 2 AND 3 i

As shown in Table 1, the error found during 1997 did not result in exceeding the 10 CFR 50.46 peak cladding temperature (PCT) limit of 2200 F.

Table 1 Limiting Large Break LOCA (LBLOCA) PCT Time Line A PCT PCT Limiting LBLOCA PCT (end of 1996)

N/A 2160 F Model Errors Discovered in 1997:

Error in the energy redistribution factor (7/97)

+40 F 2160 F*

e 1997 Penalty Factor Existing plant operating penalty credited to compensate

-40 F 2160 F*

o for the energy redistribution factor error (7/97)

Limiting LBLOCA PCT (end of1997)

N/A 2160 F (This value is reported in Updated Final Safety Analysis Report section 15.6.3.3)

The existing plant setpoints had sufficient conservatism to accomodate the penalty factor without the need to change the setpoints. Therefore, the energy redistribution factor error merely reduced the available margin in the plant j

setpoint without atTecting the PCT.

The cumulative 10CFR50.46 changes and errors are shown in Table 2.

Table 2 Cumulative 10 CFR 50.46 Changes / Errors A PCT

[lA PCT l Cumulative 10 CFR 50.46 Changes / Errors Prior to 1997 N/A

<1 F (Sum of the absolute magnitude of the 10 CFR 50.46 changes and errors found since the approval of the August 1994 LBLOCA analysis) 10 CFR 50.46 Changes / Errors Discovered in 1997:

Error in energy redistribution factor (7/97)

+40 F 40 F Cumulative 10 CFR 50.46 Changes / Errors (Sum of the N/A 40 F absolute magnitude of the 10 CFR 50'.46 changes and errors found since the approval of the August 1994 LBLOCA analysis)

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9 ENCLOSURE 3 LIMITED AUTHORIZATION TO REPRODUCE A COPYRIGHTED DOCUMENT

A ED D

7% D D October 22,1998 Via Fax: (626) 302-1922 Annette Gilliam, Esq.

Southern California Edison 2244 Walnut Grove Avenue Rosemead, CA 91770

Subject:

Limited Authorization to Reproduce a Copyrighted Document

Dear Ms. Gilliam:

In support of regulatory actions related to the San Onofre Nuclear Generating Station (SONGS), Southern Califomia Edison (Edison) recently has requested that the U.S. Nuchar Regulatory Commission (NRC) be granted permission to reproduce a Combustion Engineering, Inc. (C-E) copyrighted document which Edison is planning to submit. Accordingly, by this letter, which you may include or reference in Edison's submittal, C-E authorizes the NRC to reproduce the following C-E copyrighted document for its internal use, for filing in NRC Public Document Rooms, and for limited distribution to members of the public who may request this document from the NRC.

ABB Combust. ion Engineering Nuclear Power, Combustion Engineering, Inc., " Annual Report on C-E ECCS Codes and Methods for 10 CFR 50.46", CENPD-279, Supplement 9, CEOG Task 1024.

This authorization is subject to the following provisions:

(1)

The NRC is permitted to make that number of copies of the above-mentioned C-E copyrighted document that is reasonab!y needed for its internal use in the performance of its legitimate regulatory functions pursuant to the Atomic Energy Act of 1954, as amended, and implementing regulations or other applicable laws.

(2) in addition, the NRC is permitted to make the number of copies of the above-mentioned C-E copyrighted document necessary to have one copy available for public viewing in the relevant docket files in the NRC Public Document Rooms.

ABB Combustion Engineering Nuclear Power Robert S Ben, Jr.

Cornbustion Engineenng. Inc.

Telephone (860) 285 9780 G

al ounsel HI oa Windsor, Connecticut 06095-0500

Annette Gilliam, Etq. October 22,1998 (3)

Also, the NRC is permitted to make a single copy of the above C-E copyrighted document for members of the public who specifically request the document from the NRC.

l (4)

In all cases where the copyright notice appears on the C-E document, the copyright notice must also be included in all copies made by the NRC or by its Public Document Rooms contractors.

The specific reproduction authorization provided herein remains applicable to the subject C-E document unless terminated by C-E upon written notice to the NRC, or superseded by regulations in force covering the treatment of copyrighted submissions to the NRC.

By providing this limited authorization to the NRC, C-E does not waive any other rights and protection it has related to C-E copyrighted materials. If you have any questions on this matter, please call me.

Very truly yours,

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Robert S. Bell,'Jr.

RSB/jch cc:

J. M. Wade i

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