ML20155H732

Submits Rev to Licensing Basis LOCA Peak Clad Temperatures (Pcts) for Lgs,Units 1 & 2.Method of Reporting Changes in Licensing Basis PCT Is Being Revised to Show Changes by Fuel Type

ML20155H732
Person / Time
Site:	Limerick
Issue date:	11/04/1998
From:	Geoffrey Edwards PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9811100261
Download: ML20155H732 (4)

Text

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strtion support Department A

y 10 CFR 50.46 (a)(3)(i) and (ii) -

PECO NUCLEAR

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965 Chesterbrook Boulevard

- A Unit of PECO Energy Wayne, PA 19087 5691 November 4,1998 Docket Nos. 50-352 l

i 50-353 I

License Nos. NPF-39 l

NPF-85 l

U. S. Nuclear Regulatory Commission Attn.: Document Control Desk

' Washington, DC 20555

Subject:

. Limerick Generating Station, Units 1 and 2 10 CFR 50.46 Reporting Requirements

Dear Sir / Madam:

In accordance with.10 CFR 50.46 (a)(3)(i) and (ii), the following is a revision to the licensing basis Loss-of-Coolant Accident (LOCA) peak clad temperatures (PCTs) for Limerick Generating Station, Units 1 and 2. ' Additionally, PECO Energy Company (PECO Energy) is revising its method of reporting changes in the P

licensing basis PCT. Rather than identifying changes in licensing basis PCT by a

('

~ single value based on tne most limiting fuel type, changes will be reported by each

' fuel type.~ This change in reporting will ensure greater accuracy in reporting ll changes in the peak cladding temperatures. Table 1 (attached) provides the revised PCT values and the applicable changes. Based on the accumulated

/

i changes which result in a temperature difference of greater than 50 F from the

/l calculated baseline temperature, this report is'veing submitted within 30 days.

L On October 5,1998, General Electric Nuclear Energy (GENE) informed PECO Energy that the accumulated PCT change of 45 F previously reported was overly conservative. The revision to our Limerick SAFER /GESTR analysis in 1995 had in 1

L fact corrected one error responsible for 5 F of the 45 F total. Therefore, this 5' F change is being eliminated from our reporting basis.

The remaining 40 F applies only to the GE9, GE11, and GE13 fuel types. The PCT errcf accumulation for P8x8R and GE8 fuels is 10 F. PECO Energy had l:

conservatively applied the prior 45 F total to the limiting P8x8R fuel type in L

. previous reports. A's noted above, it is now our intention to track and report the changes by fuel type to improve clarity.

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kj GE Nuclear Energy a asanow come

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- ;=. m ssolant Accidentsfor l

Jet Pumo and Non-Jet Pump Plants.

Dunng the reportmg period an error was discovered in some applicatio>is of the GE LOCA evaluation model SAFER /GESTR. It was determined that m some analyses cases an algorithm used to compute the number of fuel rods in a BWR !sttice was incorrectly specified. As a result. SAFER input i

prepared in accordance with the automation process may hase had mcorrect data. The only unpact was on the SAFER analyses for tuel designs contaming large water rods where the mput gescration was automated. This tindmg does not impact plant saferv Q',c3C WW g y$

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D-m Contml Desk U. S. Nuclear Re~y Commission Page 2 In March 1995, a domestic utility requested that GENE review a concern regardmg the RPV bonom head drain (BHD) impact on the LOCA analysis. He concern was that because the bosom head drain line is ducctly enaW to the reactor rectreulation loops, that a recirculation line bronk LOCA would also break the BHD, and the vessel would depressurtze to the drywell faster than assumed in current models. Also, upon such an event occurring, some water required to keep the core covered to the 2/3 core height would exit the core due to either gravity or core pressure via the inter =1 =+1 recuculation and bottom head RWCU suction lines.

A GENE evaluatma <=dadad that while no analyns had been @'via.4 to precisely evalenes the PCT impact of the recirculation line break LOCA including the BHD, it is believed that the impset is 4

less than 10*F based on engmeermg judgment and extrapolation of previous LOCA analyses. Since an event is ccs.W-4 by the NRC to be signi6 cant if the PCT is increased more than 50*F (10CFR50.46 (a)(3)(i)), this amount of increase can be considered insignificant and well within the marges of the safety analysis.

De unpact of the BHD exiting flow on rp=ntammg RPV level inside the shroud is simdarly ins! - I'==

lt was determmad that a slightly higher mmimum makeup flow will be requesd, 5

however, the increased makeup is well wittun the margas of avadable ECCS systems He numissum makeup flow cormsponds to that necessary to makeup for decay heat and the drain rate from the BHD.

By copy of this letter, Licensees utilizing the GE ECCS methodology in their plant licensmg are informed of the status of changes in the evaluation methodology. Since no re-analysis or ochn=1 speci6 cation modi 6 cations are required, this submittal is believed to satisfy 10 CFR 50.46 (a) (3)(ii) for evaluation model changes without further reporting on the part ofindividual utilities.

If you have any questions, please call me or J. L. Embley at (910) 675-5774.

Sincerely, Original signed by R. J. Reda, 12/15/95 R. J. Reds. Manager Fuels and Facilities Licensing (910) 675-5889. MC J26 cc: W. J. Sependa L L. Emblev

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L) i GENuclear Enerpy oa as tw em ca m a,y e.o.au rec we emi. w a m C--- 4r 15,1995 RJR-95-118 MFN-278-95 Document Control Desk U. S. Nuclear Reguistory Comnussion Wachmstan DC 20555-0001 i

Attenna R. C. Jones, Jr.

Subject:

Reporting of Changes and Errors in ECCS Evaluation Models i

Reference:

1. Letter, J. F. Klapproth to the Document Control Desk (R. C. Jones. Jr., Reporting of Changes and Errors in ECCS Evaluation Models, dated June 24. I995 (MFN-087-95).

2. Letter, R. C. Mitchell to the Office of Nuclear Reactor Regulation. Repornng of Changes and Errors un ECCS Evaluation Models. dated July I 1994 (MFN No.

088-94).

GE is submitting this letter widch revises the Reference I letter. Revisions are marked by change bars m the margm.

' lie purpose of this letter is to report. in accordance with 10 CFR 50.46 (a) (3) (U), the impact of changes and errors in the Emergency Core Cooling Systems (ECCS) evaluation methodology used by GE. This report covers the period from the last report (Reference 2) to the present. It is noted that Peak C! adding Temperature (PCT) vanations resulting from plant specific system or fuel changes are not addressed in this letter. These should be treated as appropriate. on a plant specific basis in accordance with other sections of 10 CFR 50.

Here have been no changes or errors identified for the SAFE /REFLOOD model described in NEDE 20566-P-A, AnalyncalModeljbr Loss-o)LCoolant Analysis in Accordance sath 10 CFR 30 Appendix K.

There have been no changes or errors identified for the SAFER /GESTR model desenbed in NEDE :3785-l-P-A. The GESTR-LOCA and SAFER Models for Evaluanon <? Lass-of-Coolant

.4::: dents..nd NEDE 30996-P-A. SAFER Modeljbr Evaluanon of Loss-of-roo;.:nt.tccidents for les Pump and Non-Jet Pump Plants.

QQi l t C }M d-b 8 '

November 4,1998 Docket Nos. 50-352 50-353 TABLEI LIMERICK GENERATING STATION, UNITS i AND 2 CURRENT BASELINE PCT VALUES AND APPLICABLE CIIANGES P8x8R GE8 GE9 GE 11/13 BASELINE PCT F 1625 1515 1515 1605 CHANGES

1. MFN 278-95*

10 10 10 10 Bottom head drain

2. MFN 088-96*

0 0

30 30 Incorrect number of fuel rods TOTAL-10 10 40 40 i

ESTIMATED LICENSING 1635 1525 1555 1645 BASIS PCT

• See attachment for the associated GENE letter which reported this change. The GENE letter is identified with a "MFN" designation.

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ATTACHMENT GENE LETTERS MFN 278 MFN 088-96 I

De-Control Desk U. S. Nuclear Regulatory Comnussion Page 2

'Ihis incorrect value for the number of active fuel rods resulted from a specificataon error in an automated SAFER /GESTR basedeck generation procedure. As a result of this specification error, the SAFER /GESTR bWb for those fuel types containing large water rods (GE9/10/ll/12/13) contamed both an incorrect number of fuel rods and inappropnate values for the bundle flow areas and hydraulic A=ws. Calculations performed to assess the significance of this error indicate that the unpact on the calculated claddmg temperature is less than 30'F.

Until recently, the limiting fuel types had not been associated with the large water rod designs and the base docks.a A with :he automated prnreaire were correct. The econsistacy was ducovered as part of a normal GE quality assurance review of the SAFER /GESTR analysis for a specific plant with a large water rod limiting bundle. Actions have been taken to correct the problem and to ensure that the correct variable is used in all future applications. It should be noted that the PCT unpact was small compared to the avadable margm to specified limits demonstrated by the SAFER /GESTR results and no impact on technical specification limits was found.

All utihties using these evaluation models have been notified of this error.

If you have any questions, please call me or J. L. Embley'at (910) 675-5774.

Smcerely, R. J. Reda. Manager Fuels and Facility Licensing (910) 675-5608 cc:

W. J. Sependa J. L. Embley

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