ML20059E986

Provides Justification for Applicability of Reload Methodology Topical Repts to Facility & Requests NRC Approval for Application of Reload Analysis Methodologies

ML20059E986
Person / Time
Site:	Limerick
Issue date:	08/24/1990
From:	Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9009110053
Download: ML20059E986 (5)

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[hjm- OdlLADELPHI A ELECTRIC COMPANY

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. NUCLEAR GROUP HEADQUARTERS 4

'i 955 65 CHESTERBROOK BLVD, i[N .

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',y / August 24,'1990 '!

1 idels4o.sooo cn Docket Nos.: 50-352 ,

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U.S. Nuclear Regu.atory Commission i l

ATTN: Document Control Desk-Washington,.D.C. 20555-B <)

SUBJECT:

Limerick Generating Station Units 1-and 2 Philadelphia Electric Company In-House Reactor 1 p Core Reload Methodology Topical Reports .!

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Gentlemen: -

References 1.thrrugh 4. Identified in the Attachment, submitted'

Philadelphia Electric Company (PECo) Topical Reports describing in-house reactor

+ core: reload ~ analysis methodologies-and requested NF,C approval for their use'in; 3"

performing reload analyses for our. Peach Bottom Atomic Power Station (PBAPS),-

, Units 2 and-3. Our letter dated May 30, 1989,;"In-House Reload Licensing forc a Peach Bottom Atomic Power Station," submitted the last reload methodology 1 Topical Report. References 5 through.8 provided the NRC approval'of the' ,

r B -previous Topical Reports for PBAPS and forwarded the associated-NRC~ Safety E l:  ; Evaluation Reports-(SERs). NRCJ1etter dated June 15,,1990, approved the last~  ;

/ PEco Topical Report for PBAPS and forwarded the associated SER. The! purpose of

!, ;this' letter is.to provide justification for:the applicability of these reload- .

' methodology Topical Reports to the Limerick Generating Station (LGS),; Units 11: .

and'2, and request NRC approval of their use for LGS. Units:1,and 2. core reload- ".

,, Lanalyses. This requesi. was discussed during a conference call held,on Mayl23 L 11990,--between NRC:and PECo representatives. . Based on-that discussion, we .

Junderstand that the NRC w111:need to revlew additional infornationLto.that- -

previded below in order to-approve.PEco Topical Report PECo-FMS-0006. " Methods ,

,for'Perfoming BWR Reload Safety Evaluations," for- LGS core reload analyses.

Accordingly? we will be submitting additional information to support NRC

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approval of PEco-FMS-0006 for' LGS, Units'1 and 2 by the end of the second quarter ofL1991.

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4 Document Control Desk August 24, 1990 Page 2 1

_ _ _We request NRC approval for application of the PECo reload analysis methodologies.-described in the Topical-Reports submitted to the NRC by References 1 through 4, to the LGS, Units 1 and 2, with the same restrictions

1. specified in the NRC SERs forwarded by References 5 through 8. All of the LGS and PBAPS units are of the General Electric Boiling Water Reactor (BWR) -4 design, having very similar primary reactor systems, rated operating parameters,  :

reload fuel designs, and core loading configurations. turthermore, the PECo reactor analysis methods were developed to explicity account Q the minor differences-that do exist between PBAPS and LGS. TherG m e, eor the reasons discussed below, the computer codes and procedures described in the . Topical Reports identified in References 1 through 4 can be used to perform reload i aialyses for the LGS, Units 1 and 2 cores:

The PBAPS and LGS units are very similar from a reactor thermal-

,- hydiaulic and fuel performance standpoint. The component designs end ranges of i operation to be analyzed are essentially the same. For example, feel rods in j- the PBAPS and LGS cores are identical in design (for a given fuel product line),

l and are analyzed for fuel perfomance evaluations over the same range of power history. Sla11arly, there are no differences in fuel assembly mechanical designs between stations.for a given fuel product line. Thus, the specific PECo methods-(References 1 and 2) are equally applicable to the LGS units.

L Within the primary reactor system (i.e., Nuclear Steam Supply System,

! 'NSSS). there exists a variety of a minor physical differences (e.g., length of ,

E steam lines, number of steam separators etc.) between the PBAPS.and LGS units. '

However, these differences are not conceptual in nature (i.e...these differences l: _do'not affect the analysis methods) and the same engineering methods (i.e.,

.modelling techniques) are fully applicable to the LGS as well as PBAPS units. ..

l Specifically, the RETRAN computer code analyses for LGS will:be based upon the  !

l 'same'nodalization techniques, neutronic models, hydraulic models, etc. as those

[ developed for PBAPS (Reference 3), with physical plant design differences L explicitly accounted for using previously approved engineering methods (e.g.,

References S. 6, 7, and 8).

L From a reactor physics perspective, the PBAPS and LGS units are also very similar. All units' cores are comprised of standard, enriched uranium

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Light Water Reactor (LWR) fuel assemblies that are operated under essentially 4 identical ranges'of nodal conditions (power, pressure, temperature, moderator '

I- void content..etc.). The only significant in-core difference between the PBAPS and LGS units is the reactor core radial geometry. The geometrical differences L :between"C"(i.e.,LGSreactorcores)and"D"(i.e.,PBAPSreactorcores) )

. lattice configurations have a~ minimal impact on the methods described or results

' reported _in Reference 4. "C" lattice plants are typically loaded with L '

assemblies which have different nuclear design characteristics (i.e., fuel pin b enrichment distributions) than "D" lattice essemblies. This, however, is lessentially no'different than varying nuclear designs with a "D" lattice design; l

a typical practice used during the analysis of PBAPS reload fuel. Secondly, while. a given fuel assembly. . loaded in the same core location and operated under L

the same gross core conditions at both stations, will experience somewhat different localized (i.e., nodal) operating parameters, the overall range of

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4 Document Control Desk August 24, 1990 i Page 3 nodal operating conditions is very consistent between "C" and "D" lattice cores, further supporting the applicability of the_PCAPS steady-state core physics methodology benchmarks to LGS. We also note that our core physics methods explicitly evaluate and ace wnt for observed differences between unit operating- 3 data and pure analytical so v ons. While the observed accuracy of our core

. physics methods may vary somewhat from unit to unit and from fuel cycle to fuel

! cycle. the NRC SERs state that the technigees used by PECo to account for core i

~ modelling biases and uncertainties are reasonable. Finally, much of the L benchmarking reported in Reference 4 (i.e., isotopic inventory, fuel pin power L distributions, reactivity cuefficients, etc.) is of a_ generic nature, reflecting a variety of plant designs, fuel designs, and core configurations. This e confirms the general applicability of our core physics methods to a wide range of reactor designs and analyses.  ;

l; The fact that many of the benchmarks also discussed in the referenced L PECo reports are of a generic nature is significant. Examples of this include

? benchmarks to the ATLAS test loop critical quality data, Yankee Rowe isotopics

measurements, Halden fuel performance test rods, Kritz pin power distribution  !

_ data, A.B. Atomenergi Doppler measurements PECo/ Yankee Atomic /Studsvik Energiteknik-AB KENO-IV (Monte Carlo Program) pin power and reactivity

' coefficient re mits, and the NRC RETRAN-02 standasd test problem. Reliance on

. generic be*:hmarks and safety evaluations which frequently reflect different LWR reactor de igns, fuel designs, and core loading configurations is _a cosmion  ?

Industry p actice for benchmarking methods. A substantial portion of the-material presented in the referenced reports is, therefore, equally applicable H to the LGS units as it is.to the PBAPS units.

The NRC has approved our reactor analysis methods for application to the PBAPS units' core reloads (References 5. 6. 7, and 8) based on a significant volume of generic industry benchmarks, generic computer safety evaluations, and

-a variety of PBAPS specific qualification studies. The methods that we employ have been demonstrated.tc be applicable to a variety of LWR designs, fuel

. designs, and core loading configuratione by a number of other licensees and i vendors. The NRC has also cited, in References 5, 6, 7, and 8, the expertisa of J PECo personnel .and the acceptability of the engineering methods which we apply to the PBAPS reactor analyses, methods'which account for observed biases and uncertainties relative to actual plant data. ,

Based on the above discussion, and the fact that the PBAPS and LGS

--units are.BWR-4s with primary reactor systems and cores configured in a nearly-identical manner, we consider that there is sufficient justification for the NRC to approve this request to use the methods described in References 1, 2, 3, and 4 for the core reload analyses for LGS, Units 1 and 2. As stated in the referenced PECo reports, w will continue to monitor the accuracy of our core reload analysis methods relative to measurements obtained from both the PBAPS and LGS units to assure the continued applicability of these methods.

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. ..'If you have any questions;.or require additional.information, please-contact us;.

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' i Q i, Very.truly yours, y

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m  : G. .- nger, Jr.

Je 4 ' Manager- :

Licensing Section .

Nuclear Engineering.and Services 1- ~!

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L i Attachment'.

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a > < .T. T. Martin,-Administrator,' Region I, USNRC-l1 1 ~ .cc: LT.LJ. Kenny, USNRC Senior Resident. Inspector, LGS m g a; I t i 4 i f

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K i Ref erences'-

- 1. Letter from S. L. Daltroff (PECo) to D. R. Muller (NRC) " Philadelphia Electric Company In-House Reload Licensing " dated August 29, 1986.

2. Letter from J. W. Gallagher (PECo) to W. R. Butler (NRC) "Pn11adelphia Electric Company.in-House Reload Licensing Methods Reports," dated July b '

13, 1987, t

3. LetterfromJ.W.Gallagher(PECo) tow.R.'3utler(NRC)," Philadelphia:

Electric Company-In-House Reload Licensing," dated September _ 28, 1987.

h .4. Letter fron'J. W. Gallagher (PECo) to W.LR.-Butler-(NRC), " Philadelphia Electric' Company In-House Reload Licensing," dated. february 1, 1988.

S. Letter fros'R. E. Martin-(NRC) to E. G. Bauer (PECo)', " Safety Evaluation for Reports PECo-FMS-0001 and PEco-FMS-0002 for. Core Reload Analyses,"

dated October 22,.1987.

f6. Leh ar from R. E. Martin (NRC) to G. A. Hunger, Jr. -(PECo\, " Safety Evaluation of PEco's FROSSTEY Fuel' Performance Code: PECo-FMS-0003."

_ dated September 21. 1989.

7. Letter.from R.'E. Martin (NRC) to G. A. Hunger, Jr. (PECo), " Safety Evaluation for Topical Report PECo-FMS-0004, ' Methods for Performing BWR

' System Transient Analysis' " dated November-23, 198".

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8. - Letter from Gene -Y. Suh (NRC) to G. A. Hunger, Jr. (PECo), " Safety Evaluation for Topical Report PECo-FMS-0005, ' Methods for Performing BWR Steady-State Reactor Physics Analyt.es'," dated November 9, 1989.

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