ML20212A976

Submits 1999 Annual Rept of Any Changes or Errors Identified in ECCS Analytical Models or Applications

ML20212A976
Person / Time
Site:	Monticello
Issue date:	09/09/1999
From:	Hammer M NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9909170213
Download: ML20212A976 (5)

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! Northern States Power Company N Monticello Nuclear Generating Plant

~f 2807 West County Road 75 Monticello, MN 55362 September 9,1999 10CFR Part 50 Section 50.46(a)(3) j US Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 j l

MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 l

1999 Report of Changes and Errors in ECCS Evaluation Models  ;

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References:

1.) GE Report NEDC-32514P, Revision 1, *Monticello SAFER /GESTR-LOCA Loss-of- l Coolant Accident Analysis," dated October 1997. This report is Exhibit G of " Revision 1 to License Amendment Request dated July 26,1996 supporting the Monticello Nuclear Generating Plant Power Rerate Program," from Michael F. Hammer (NSP) to US NRC Document Control Desk, December 4,1997.

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2.) GE Letter TGR:99-043, Letter from TG Reason to TJ Asmus (NSP), " Summary of Changes and Errors in ECCS Evaluation Models", dated July 28,1999. (Attached) 3.) GE Letter TGR:99-033, Letter from TG Reason to TJ Asmus (NSP), Regarding y Counter Current Flow Limiting (CCFL) Coefficients in SAFER Analyses for GE8, GE9, GE10, and Siemens Fuel, dated July 1,1999. (Attached) {U Pursuant to 10 CFR 50.46(a)(3) the following is the required annual report of any change or error identified in ECCS analytical models or their application. Monticello's LOCA analysis of record (AOR)is contained in the License Amendment Request for Plant Rerate (Reference 1). Correspondence, from GE to NSP, reporting errors and 9909170213 990909 PDR ADOCK 05000263 R PDR 9/9/99 Jr\LICENSI F#Klodic P&J+0ftB\lCCS,99.kPT. doc

r changes to the ECCS Analysis are denoted as Reference 2 and Reference 3. No changes or errors to the GE11 Peak Clad Temperature (PCT) were reported during the period from July 1998 through June 1999.

Reference 3 identified the following error in the GE10 PCT. The SAFER code models counter current flow limiting (CCFL)in the upper part of the bundle at the upper tie plate (UTP). The CCFL correlation uses the UTP flow area and a coefficient based on test data to determine the liquid downflow into the bundle. For fuel designs in which CCFL is expected to occur at the top spacer due to enlarged UTP flow areas, the CCFL constant must be adjusted for the difference in flow areas at the spacer and UTP. This was recognized for GE11 and later fuel types, but was not applied to GE10 or Siemens fuel. As a result of this error, Monticello was assessed a 5 F penalty on GE10 PCT; the Licensing Basis PCT increased from 1922 *F to 1927 F. The GE10 PCT remains well below the 2200 *F limit The table below summarizes the calculated Peak Clad Temperature (PCT) from the AOR.

Monticello Licensing Basis Peak Clad Temperatures Fuel Type PCT ('F) Reference GE10 1927 2, 3 GE11 2087 1 GE12 (See note a) (See note a)

SPC 9x9-IX (See note b) (See note b) a.) The GE12 lead use assemblies are bounded by the GE11 LOCA analysis due to the following:

(1) GE12 design has a greater number of fuel rods, resulting in initial temperatures and stored energy lower than GE11 assemblies.

(2) GE12 fuel has a greater heat transfer area than GE11 fuel, which improves heat transfer characteristics during a LOCA.

(3) The GE12 bundles are specifically designed to have lower linear heat generation rates than the coresident GE11 fuel.

b.) The SPC 9x9-lX qualification fuel assemblies (QFAs) are bounded by the GE10 LOCA analysis for the following reasons:

(1) The SPC 9x9-lX QFA design has a greater number of fuel rods, resulting in lower initial temperatures and stored energy as compared to the GE10 assemblies.

(2) The SPC9x9-IX QFA design has a greater heat transfer area than GE10 fuel, which improves heat transfer characteristics during a LOCA.

(3) The SPC 9x9-IX design has a larger water channel than the GE10, which improves LOCA performance by providing additional heat sinks during the batup period of the accident.

General Electric performed sensitivity studies to illustrate the effect of alternate operating modes on PCT. Of particular interest for Monticello is the effect of the

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i-maximum extended load line limit analysis (MELLLA) on PCT (see Reference 1),

g because this is a common mode of operation. The treatment of SAFER calculations performed for alternate operating modes as sensitivity studies was questioned during the BWROG/NUPIC Technical Assessment of GE LOCA Analysis Methods. Current  !

practice defines the licensing basis PCT at nominal operating conditions; alternate i' operating modes in which the plant may frequently operate (e.g., MELLLA) are addressed in such sensitivity studies. This issue is being considered by the BWROG and GE, and will be addressed by GE in correspondence to the NRC later this year.

NSP will continue to follow the progress of this issue through its participation in the BWROG.

This letter contains no new commitments nor does it modify any existing commitments.

Please contact Marcus Voth, Project Manager of Licensing at (612) 271-5116 if you require further information.

t24s++tiv Michael F. Hammer Site General Manager Monticello Nuclear Generating Plant c

Regional Administrator-lil, NRC NRR Project Manager, NRC Sr. Resident inspector, NRC State of Minnesota l Attn: Steve Minn  !

J E Silberg I I

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GE Nuclear Energy

, Tammy G. Reason ' lac:ur .* vel Pmourt Mana<ternent l*wl Pf07.1 f.fanaucf 'ner31 EwClrtC ComCany

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Mdmn; tan. NClS.:in C180 JI]675 5752 DC 2':92 5752. fas :010 6?S SGN l'syer co33251611 isvury Heiacma pne ge wm July 1,1999 '- cc: C. A. Bonneau TGR:99-033 J. E. Fawks H. H. Paustian R. A. Rossi D. G. Wegener Mr. T. J. Asmus Senior Engineer, Fuel Resources Northern States Power Company 414 Nicollet Mall- Ren Sq 10 Minneapolis, MN 55401-1927 .

Dear Tom:

Following is a GE notification to our customers concerning Counter Current Flow Limiting (CCFL) Coefficients in SAFER Analyses for GE8, GE9, GE10 and Siemens Fuels. Please note

- that this error has a 5' impact on Monticello's Peak cladding temperature. This should be reviewed by your team to determine 10CFR50.46 reportability.

If you have any questions, please contact me.

B.st reg ds, aJ w T. G. Reason e

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GE Nuclear Energy l Tammr G. Reason huch. fuelPunsuctMwagement EnelProtect Manaaer GeneralElecinc Comoany Castle Hayne %d. P O Su /80. M:C A))

Nirntngton. NC 28401-0780

?!O 675 5752. DC 8~222 5752. Fax : 106755684 Pmjer 8883251674 rammy steasonuvyene ye corn July 28,1999 cc: C. A. Bonneau TGR:99-043 J. E. Fawks M. A. Higar H. H. Paustian

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R. A. Rossi )

D. G. Wegener )

Mr. T. J. Asmus Senior Engineer, Fuel Resources Northern States Power Company

- 414 Nicollet Mall - Ren Sq 10 Minneapolis, MN 55401-1927

Subject:

Summary of Changes and Errors in ECCS Evaluation Models

Reference:

1. NRC Information Notice 9715, dated April 4,1997.

2. TGR:99-033 Counter Current Flow Limiting (CCFL) Coefficients in SAFER Analyses for GE8, GE9, GE10 and Siemens Fuel dated July 1,1999

Dear Tom:

Enclosed is a copy of the annual letter recently sent to the NRC summarizing the impact of changes and .

errors in the methodology used by GE to demonstrate compliance with the Emergency Core Cooling System (ECCS) requirements of 10CFR50.46.

These changes and errors have previously been reported to affected utilities (Reference 2).

The enclosed notification letter to the NRC does not satisfy the licensee reporting requirements per 10 CFR 50.46(a)(3)(ii), however, per Reference 1, licensees may reference this notification in their annual j report.

e If you have any questions, please call me.

m Best reg ,

bA AS -

T. G. Reason