ML17306B374

Forwards Nonproprietary & Proprietary Versions of Rev 0 to Reload Analysis Methodology for Pvngs. Proprietary Version Withheld (Ref 10CFR2.790(b)(1)

ML17306B374
Person / Time
Site:	Palo Verde
Issue date:	04/06/1993
From:	Conway W ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML17306B375	List: ML17306B374 ML20035D296
References
102-02469-WFC-J, 102-2469-WFC-J, NUDOCS 9304130030
Download: ML17306B374 (28)

Text

D ACCEI ERA DOCUMENT DIST VTION'SYSTEM REGULAT L'NFORMATION DISTRIBUTIO SYSTEM (RIDS)

ACCESSION NBR:9304130030 DOC.DATE: 93/04/06 NOTARIZED: YES DOCKET FACIL:STN-~50-528 Palo Verde Nuclear Station, Unit 1, Arizona Publi 05000528 STN-50-529 Palo Verde Nuclear Station, Unit 2, Arizona Publi 05000529 STN-50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi 05000530 AUTH.NAME AUTHOR AFFILIATION CONWAY,W.F.

Arizona Public Service Co. (formerly Arizona Nuclear Power RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk)P~r P'UBJECT:

Forwards nonproprietary

& proprietary versions of Rev 0 to "Reload Analysis Methodology for PVNGS." Proprietary version withheld (ref 10CFR2.790(b)(l).

DISTRIBUTION CODE:

BPOID COPIES RECEIVED:LTR l

ENCL g SIZE: l +gLf TITLE: Proprietary Review Distribution Pre Operating License

& 0 crating R

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NOTES:STANDARDIZED PLANT Standardized plant.

Standardized plant.

05000528 A

05000529 05000530 RECIPIENT ID CODE/NAME PD5 LA TRAMMELL,C COPIES LTTR ENCL 1

1 3

3 RECIPIENT ID CODE/NAME PD5 PD TRAN,L COPIES LTTR ENCL 1

1 3

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INTERNAL: ACRS OGC/HDS1 EXTERNAL: NRC PDR 6

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FIL 01 1-1 1

1 NOTE TO ALL"RIDS" RECIPIENTS:

PLEASE HELP US TO REDUCE WASTEI CONTACT THE DOCUMENT CONTROL DESK, ROOM Pl-37 (EXT. 504-2065) TO ELIMINATEYOUR NAME FROM DISTRIBUTION LISTS FOR DOCUMENTS YOU DON'T NEED!

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Arizona Public Service Company P.o, BOX 53999

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PHOENIX. ARIZONA85072<999 WILLIAMF. CONWAY EXECUTIVEVICEPRESI0ENT NUCLEAR 102-02469-WFC/JRP April 6, 1993 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P17 Washington, DC 20555

References:

1)

Letter 102-02360, dated November 25, 1992, from W. F. Conway, Executive Vice President, Nuclear, APS, to USNRC, 'Reload Analysis Methodology Report')

Letter dated January 26, 1993, from C. M. Trammell, Senior Project Manager, Division of Reactor Projects, USNRC, to W. F. Conway, Executive Vice President, Nuclear, APS, 'Reload Methodology Topical Report'ear Sirs:

SubJect:

Palo Verde Nuclear Generating Station (PVNGS)

Units 1, 2, and 3 Docket Nos. STN 50-528/529/530 Response to Request for Additional Information Regarding Reload Analysis Methodology Report File: 93-056-026 Enclosed, please find the Reload Analysis Methodology Report for PVNGS Units 1, 2, and 3, Revision OO-P, dated February 1993, which supersedes the report transmitted by Reference 1.

This report summarizes the program undertaken by Arizona Public Service Company (APS) to develop the capability to perform reload analysis.

Pursuant to Section 2.790(b)(1) of the regulations of the NRC, APS herewith submits an affidavit for consideration by the Commission in determining whether information sought to be withheld from public disclosure, included in the enclosed Reload Analysis Methodology Report, should be withheld. In addition to the proprietary version, Revision 00-NP is enclosed as a non-proprietaIy version where information sought to be withheld from public disclosure has been bracketed and deleted.

Also enclosed is the APS response to Reference 2.

Should you have any questions, please call Thomas R. Bradish at (602) 393-5421.

WFC/JR P/rv j.20084 9304130030 930406 PDR ADOCK 05000528 P

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U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Reload Analysis Methodology Report Page 2

Enclosures:

1 - Revision 00-P (Proprietary) 2 - Revision 00-NP (Non-Proprietary) 3 - Affidavit 4 - Response to Request for Additional'Information cc:

J. B. Martin J. A. Sloan C. M. Trammell

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ENCLOSURE 3 AFFIDAVIT

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AFFIDAVIT PURSUANT TO 10 CFR 2.790 Combustion Engineering, Inc.

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State of Connecticut

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County of Hartford

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SS.:

I, S. A. Toelle, depose and say that I am the Manager, -Nuclear Licensing, of Combustion Engineering, Inc., duly authorized to make this affidavit, and have reviewed or caused to have reviewed the information which is identified as proprietary and referenced in the paragraph immediately below.

I am submitting this affidavit in conjunction with Arizona Public Service Company in conformance with the provisions of 10 CFR 2.790 of the Commission's regulations for withholding this information.

The information for which proprietary treatment is sought is contained in the following document:

"Reload Analysis Methodology for the Palo Verde Nuclear Generating

Station, Revision OO-P," February 1993.

This document has been appropriately designated as proprietary.

I have personal knowledge of the criteria and procedures utilized by Combustion Engineering in designating information as a

trade secret, privileged or as confidential commercial or financial information.

Pursuant to the provisions of paragraph (b)

(4) of Section 2.790 of the Commission s regulations, the following is furnished for

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consideration by the Commission in determining whether the information sought to be withheld from public disclosure, included in the above referenced

document, should be withheld.

2.

The information sought to be withheld from public disclosure, which is owned and has been held in confidence by Combustion Engineering, is the reload design

process, including the computer programs utilized and the scope of analyses performed for the Palo Verde Nuclear Generating Station.

The information consists of test data or other similar data 3 ~

4 ~

concerning a process, method or component, the application of which results in substantial competitive advantage to Combustion Engineering.

The information is of a type customarily held in confidence by Combustion Engineering and not customarily disclosed to the public.

Combustion Engineering has a rational basis for determining the types of information customarily held in confidence by it and, in that connection, utilizes a system to determine when and whether to hold certain types of information in confidence.

The details of the aforementioned system were provided to the Nuclear Regulatory Commission via letter DP-537 from F.

M. Stern to Frank Schroeder dated December 2,

1974.

This system was applied in determining that the subject document herein is proprietary.

The information is being transmitted to the Commission in confidence under the provisions of 10 CFR 2.790 with the

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understanding that it is to be received in confidence by the Commission.

The information, to the best of my knowledge and belief, is not available in public sources, and any disclosure to third parties has been made pursuant to regulatory provisions or proprietary agreements which provide for maintenance of the information in confidence.

Public disclosure of the information is likely to cause substantial harm to the competitive position of Combustion Engineering because:

a ~

b.

A similar product is manufactured and sold by major pressurized water reactor competitors of Combustion Engineering.

Development of this information by C-E required tens of thousands of manhours and millions of dollars.

To the best of my knowledge and belief, a competitor would have to undergo similar expense in generating equivalent information.

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d.

In order to acquire such information, a competitor would also require considerable time and inconvenience to develop the reload design process, including the computer programs utilized and the scope of analyses performed for the Palo Verde Nuclear Generating Station.

The information required significant effort and expense to obtain the licensing approvals necessary for application of the information.

Avoidance of this expense would decrease

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a competitor's cost in applying the information and marketing the product to which the information is applicable.

The information consists of the reload design

process, f

including the computer programs utilized and the scope of analyses performed for the Palo Verde Nuclear Generating

Station, the application of which provides a competitive economic advantage.

The availability of such information to competitors would enable them to modify their product to better compete with Combustion Engineering, take marketing or other actions to improve their product's position or impair the position of Combustion Engineering s product, and avoid developing similar data and analyses in support of their processes, methods or apparatus.

In pricing Combustion Engineering s products and services, significant research, development, engineering, analytical, manufacturing, licensing, quality assurance and other costs and expenses must be included.

The ability of Combustion Engineering's competitors to utilize such information without similar expenditure of resources may enable them to sell at prices reflecting significantly lower costs.

Use of the information by competitors in the international marketplace would increase their ability to market nuclear steam supply systems by reducing the costs associated with their technology development.

In addition, disclosure would have an adverse economic impact on Combustion

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s Engineering's potential for obtaining or maintaining foreign licensees.

Further the deponent sayeth not.

S. A. Toelle Manager Nuclear Licensing Sworn to before me this ~l'A day of 1993 Notary., Pub ic

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My commission expires: 3-3 -9

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ENCLOSURE 4 RESPONSE TO REQUEST FOR ADDITIONALINFORMATION

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RESPONSE TO REQUEST FOR ADDITIONALINFORMATION P

The topical is marked proprietary but specific proprietary information is not bracketed.

A~PS R The enclosed Reload Analysis Methodology Report forthe Palo Verde Nuclear Generating Station, Revision OO-P, dated February 1993, has the proprietary information bracketed.

Also enclosed is a non-proprietary version, Revision OO-NP, dated February 1993, with the proprietary information bracketed and deleted.

These enclosures supersede the Reload Analysis Methodology Report transmitted by reference 1 of the cover letter.

NRC Question 2 Reference is made to a Boron Dilution Alarm System (BDAS) to alert the operator to a boron dilution event.

The BDAS setpoint is based on a relative fractional increase in subcritical multiplication and is evaluated during each reload analysis.

In view of the recent problems encountered with the Westinghouse Boron Dilution Mitigation System, which used the same type of input for initiation, there should be additional discussion pertaining to the acceptability of the BDAS setpoint including such items as uncertainties and inverse count rate vs. boron concentration relationship.

APS Res onse Unlike the Westinghouse Boron Dilution Mitigation System, the PVNGS Boron Dilution Alarm System (BDAS) is a digital system which willalarm when the sampled average flux signal exceeds the stored base flux signal level by a fixed ratio. The base flux level will remain constant unless reset by the operator.

A drop in boron concentration would enhance the sampled fluxsignal compared to the base flux level since the measured flux ratio is higher than=the actual increase in subcritical multiplication, thus the alarm will come in earlier than required.

Therefore, the drop in boron concentration will result in a conservative alarm point.

The reload analysis of the BDAS setpoint is based on verification of the installed alarm setpoint.

The system is set to alarm at a flux ratio of 1.7.

Uncertainties accountable to instrumentation, setpoint, flux signal, and software, raise the analysis setpoint to 2.2.

Calculated flux ratios of greater than 2.2 are acceptable.

The ratios calculated for the independent analysis ranged from 3.3 to 8.4.

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NRC uestion 3 Recently, it was determined that CE plants may be operating with non-conservative tilt values in the TS due to the fact that larger values may have been assumed in the safety analyses.

The topical report should address which transients assume an initial azimuthal tilt and what maximum value is assumed.

APS Res onse Neutronics models which are used to calculate physics parameters for input to the safety analysis do not include any explicit azimuthal-tilt.

Hence all parameters which are dependent upon local power distribution effects are augmented to allow for maximum allowed tilt. Both reactivity inserted and power peaking distortion factors are adjusted where appropriate, primarily in transients involving anomalous CEA motion such as single CEA drop or CEA ejection.

However, core-wide parameters such as MTC and the cooldown curve (reactivity insertion vs. moderator temperature) for Steam Line Break, do not require any adjustments for tilt.

The safety and setpoint analyses presented in the enclosed Reload Analysis Methodology Report assumed a maximum 3 percent steady state azimuthal power tiltat powers greater than 20 percent for the conditions of COLSS Out-Of-Service (COOS) and/or CEACs inoperable because that was standard CE methodology.

However, we have realized that the current Technical Specifications allow a maximum 10 percent azimuthal power tiltfor the same conditions. An evaluation is being conducted to determine if a new safety and setpoint analysis should be performed, or the Technical Specifications changed so that the azimuthal power tilt limit is consistent with the current analyzed conditions of COOS and/or CEACs inoperable.

Currently, administrative controls are in place to ensure that the analyses for the conditions of COOS and/or CEACs inoperable are conservative ifthe measured tilt exceeds 3 percent.

This is accomplished by making appropriate adjustments to the CPC addressable constants.

NRC uestion 4 Statistical convolution is used forthe CEA ejection, locked rotor, and inadvertent opening of a SGADV to determine the number of fuel rods in DNB.

Do any other events use convolution?

APS Res onse As discussed in the enclosed Reload Analysis Methodology Report, the statistical convolution technique is currently used for the following events,

1) CEA ejection, 2) locked rotor, and 3) inadvertent opening of a, SGADV, to determine the number of fuel rods in DNB. No other events use the convolution technique.

NRC uestion 5 Comparisons to CE results are somewhat muddled since the APS Cycle 3 calculations were done for a longer Cycle 2 cycle length that the CE calculations and beyond the actual Cycle 2 burnup.

It would seem that proper benchmarking would require identical initial conditions.

Although, for the most part, the differences between the results are small, it is difficultto determine whether the comparisons would be better or worse for identical initial conditions.

APS Res onse The analyzed cycle lengths (burnup windows) were different for a reason.

The APS analysis was based on a contingency schedule in case Unit 3 Cycle 2 did not enter the CE analysis shutdown window in time to avoid a refueling outage in the summer.

Both the APS and CE designs used the Unit 3 Cycle 3 fuel management pattern developed by APS as the starting point. The CE analysis was based on a best estimate Unit 3 Cycle 2

schedule, EOC occurring in the spring of 1991 with a cumulative burnup between 384 EFPD and 436 EFPD.

The APS analysis was based on a contingent schedule, delaying the scheduled Unit 3 Cycle 2 EOC until the fall of 1991, with a termination burnup between 436 EFPD and 458 EFPD.

Ultimately, the Unit 3 Cycle 2 EOC occurred on March 16, 1991, at 390.8 EFPD (within the CE analyzed burnup window).

Identical initial conditions would have made better comparisons.

However, the comparisons between APS and CE results show excellent agreement.

The basis for any minor differences have been thoroughly investigated to demonstrate that the differences were not the result of incorrect applications of the CE methodology.

As expected, the results of the comparison show that the small difference in cycle lengths did not have any significant impact on the reload analysis results.

This is because,

1) physics parameters used in analysis of BOC transients are either based on Technical Specification limits (MTC) or vary slowly and smoothly with the shutdown burnup of the previous cycle, and

2) physics parameters used in analysis of EOC transients are again either based on Technical Specifications or are affected by the maximum fuel burnup achieved, which was explicitly accounted for within the APS analyses.

Furthermore, the APS design calculations for the independent analysis were forwarded to CE for a technical review. 'This was done to verify the ability of APS to correctly implement CE models and methods which was confirmed in CE's letter on their review of the APS Reload Topical Report (

Reference:

Letter from N. J. Breckenridge [C-E] to P. F. Crawley [APS], "ABB CE Review of the APS Reload Topical Report," V-92-237, November 30, 1992).

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NRC uestion 6 Since the LOCA analysis is done by CE, is the input to the LOCA analysis supplied to CE by APS or is it generated by CE? What effect do the differences between the APS and CE calculated parameters that are input to LOCA analysis have on LOCA results?

APS Res onse In the event that APS performs a reload analysis independent of CE, APS would supply to CE the cycle dependent input required for the LOCA analysis.

For the case presented in the Reload Analysis Methodology Report, the input to the LOCA analysis for Unit 3 Cycle 3 was generated by CE. APS generated LOCA data for the alternate Cycle 2 endpoint, but CE did not perform the LOCA analysis for the APS design since there was no need.

Had Unit 3 Cycle 2 entered the APS analyzed burnup window, CE would have performed the appropriate LOCA analysis with the APS input.

Key input parameters to the LOCA analysis such as the hot pin average temperature, centerline temperature, gap conductance, and rod internal pressures were compared and presented in Section 4.3 of the enclosed Reload Analysis Methodology Report. The gap conductance and temperature results were nearly the same, and the slight discrepancy in rod internal pressures was found to be acceptable.

Therefore, the effect of the differences on the LOCA results is expected to be negligible.

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