ML20128F583

Submits Response to Request for Additional Information Regarding Revision to License Change Request 96-01 Re Safety Limit MCPR Due to Use of GE13 Fuel Product Line

ML20128F583
Person / Time
Site:	Peach Bottom
Issue date:	09/27/1996
From:	Hunger G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9610080131
Download: ML20128F583 (5)

Text

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Ct tion tupport Depirtmrnt

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PECO NUCLEAR neo-c-965 Chested > rock Boulevard A Unit of PECO Energy wayne. PA 19087-5691 September 27,1996 Docket Nos. 50-277 50-278 License Nos. DPR-44 DPR 56 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555

Subject:

Peach Bottom Atomic Power Station, Units 2 and 3 Response to Request for Additional Information Regarding Revision to License Change Request No. 96-01

Dear Sir:

Attached is our response to your Request for Additional Information (RAI), discussed in our telephone conversation on September 26,1996 regarding the new Safety Limit Minimum Critical Power Ratios (GLMCPRs) due to the use of the GE13 fuel product line. Revision to License Change Request No. 96-01 was forwarded to you by letter dated August 23,1996.

The specific issues addressed in this response are as follows:

1) Explain what is meant by " conservative variations of projected control blade pattems."

2) Explain the difference between the cycle-specific (PBAPS, Unit 2, Cycle 12) SLMCPR value of 1.11 and the Generic GE13 SLMCPR value of 1.09 (i.e., the difference of 0.02).

The response to these two issues is attached in the letter from R. M. Butrovich (GE Nuclear Energy) to H. J. Diamond (PECO Energy), " Peach Bottom 2 Cycle 12 SLMCPR Licensing Clarification," dated September 26,1996.

As discussed in your letter dated September 5,1996, conceming this subject, if circumstances change during the notice period such that failure to act in a timely way would result, for example, in l derating or shutdown of the facility, the Commission may issue the license amendment before the  ;

expiration of the 30-day notice period. We currently anticipate that start up of PBAPS, Unit 2 could occur as early as midni0ht Saturday, September 28,1996. In order to avoid holding the reactor in a derated condition, we request that you issue this amendment by 11:00 pm Saturday, September 28,1996.

If you have any questions, please do not hesitate to contact us.

Very truly yours,

. . t -

G. A. Hunger, Jr.,

D; rector- Licensing

/

Enclosures:

Affidavit, Attachment cc: H. J. Miller, Administrator, Region I, USNRC W. L. Schmidt, USNRC Senior Resident inspector, PBAPS R. R. Janati, Commonwealth of Pennsylvania sn 9610000131 960927 PDR ADOCK 05000277 P PDR

. . . COMMONWEALTH OF PENNSYLVANIA :

ss.

COUNTY OF CHESTER  : 1 l

D. B. Fetters, being first duly swom, deposes and says:

i That he is Vice President of PECO Energy; the Applicant herein; that he has read I the enclosed response to the NRC Request for Additional Information involving the Revision to License Change Request No. 96-01 for Peach Bottom Atomic Power Station, Units 2 and 3, Facility Operating License Nos. DPR-44 and DPR-56, and knows the contents thereof; and that the statements and matters set forth therein are true and correct to the best of his knowledge, information and belief.

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Vice President Subscribed and sworn to before me thisc 2 day of 1996. -

Notary Public Notariai Geat f

Mary Lou Skrocki. Notary Pub'i0 {

! i Tredyffrin Twp., Chester Cor.y r

{' t.'y commasion Erp res fily 17, W-n 1 .. ' F:.

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EEP-27-23 $7:31 FROM GE-NUCLEAR FUEL ids 9103735SS4 PAGE 1/3 l GENuclextEnergy j , , , , ,, . . . - . . . .. . . . .

Richard M Butrovich Nuclear fuel. Anernas Fo*t141ea Mmmer Gerwatkuw company Caslie Nbyne b,,d PO Bus 780. M cA33 W#wgton. NC 2M010180 9106?$.6266 Das Coon 8 '2916)66 September 26,1996 "'*

cc: D. B. Wahermire RMB:96-215 C. L. Heck J. L. Rash J. M. Carmody Mr. H. J. Diamond, Director Fuel & Services Division

• PECO ENERGY COMPANY 965 Chesterbrook Boulevard Wayne, PA 19087-5691

SUBJECT:

Peach Bottom 2 Cycle 12 SLMCPR Ucensing Clarification

REFERENCES:

1. NEDC-32505P, R-Factw Calculation Methodfw GE11, GE12 andGE13 Fuel, November 1995.

2. Licensing Topical Report, GeneralElectric BWR Thermal Analysis Basis (GETAB): Data, Cwrelation andDesign Application, NEDO-10958-A, January 1977.

3. GeneralElectric StandardApplicationfw Reactw Fuel, NEDE.

24011-P-A-13-US, August 1996.

Here are responses to the two questions, verbalized during our conference call with the l NRC on September 26,19%, regarding the SLMCPR for Peach Bottom 2 Cycle 12. The questions were verbalized as follows and accompanying them is GE's response:

1. Please provide clarification of " conservative variations ofprojectedcontrolblade patterns" used to calculate the SLMCPR for Peach Bottom 2 Cycle 12.

Projected control blade patterns for the rodded burn through the cycle are used to deplete the core to the cycle exposures to be analyzed At the desired cycle exposures, the bundle exposurt distributions and their associated R-factors, determined in accordance with Reference 1, are then utilized for the SLMCPR cases to be analyzed. Using different rod patterns, to achieve the desired cycle exposure, has been shown to have a negligible impact on the actual SLMCPR calculated. An estimated SLMCPR is obtained for an exposure point near beginning of cycle (BOC) and end of cycle (EOC), as well as the calculated cycle exposure for peak hot excess reactivity (PHE), in order to establish which l

SEP 27 '96 8:33 0106755684 PAGE.001

SEP-27-93 07,32 FROMsGE-NUCLEAR FUEL ids 91eG755684 PAGE 2/3

, Mr. H. J. Diamond 2 9/26/96

" exposure point (s) will produce the highest (most conservative) calculated .

tnese exposure points, the goal of page IV-7 ofReference 2 is applied:

"The objective in establishing the initial condition power distribution is to satisfy total power and local limits and to maximize the calculated number ofrods expected to experience boiling transition."

His is achieved by following the rule on page IV-6 in Reference 2.

"For a given reactor, at a particular exposure, there is a variety of rod pattems which produce k,e = 1.0 [withm the established tolerances] and satisfy local power and MCPR constraints. For conservatism, the statistical analyses of the core are performed for only those operating states yielding MCPR equal to the limit, unless this involves an unreasonable power distribution or gross violation of kW/P. limits."

To maxunize the calculated SLMCPR value at the exposure point ofinterest, different control rod pattems are evaluated to find the pattems that yield the most bundles on or near the operating limit MCPR at this cycle exposure point. His is what is meant by "comervative wiriations ofprojectedcontrolbladepattems". ne variations are conservative since they are selected to maximize the number ofrods susceptible to transition by mavimimg the number ofcontributing bundles. For Peach Bottom 2 Cy 12 analysis, 36 control blade patterns were attempted to meet this criteria to achieve the objective stated earlier, to place the most bundles (and rods) on limits. It becomes clear when performing these calculations that an asymptote is reached where the number of bundles close to limits is maximwed. Often, as is the case for this core, there will be several different viable control blade patterns that produce equivalent numbers of bundles on/close to limits. In this case the Monte Carlo calculations were performed for each of these patterns. He highest SLMCPR, from these patterns that met the criteria above chosen as the cycle specific SLMCPR value. His occurred at the near end ofcycle exposure point.

2. Please explain why the Peach Bottom 2 Cycle 12 SLMCPRis 1.11 versus the generic GE13 value of 1.09.

According to the latest approved revision of GESTAR II (Reference 3), the SLMCPR analysis for a new fuel design shall be performed for a bounding equihtrium core. His is how the 1.09 value was obtained for the GE13 product line. However, Peach Bottom 2 Cycle 12 is not an equilibrium core. It is a mixed core of gel 1/GE13 fuel. Over the last several cycles, the average enrichment for the fresh fuel has progressively increased.

Higher enrichment in the fresh fuel (compared to the rest of the core) produces higher power in the fresh bundles which causes more rods to be susceptible to boiling transition in the statistical analyas than for an equilibrium core. In cores that operate for two years it is typical that almoci all of the bundles close to the knuting MCPR of the core are fresh SEP 27 '96 8:33 8106755G84 PAGE.002

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SEP-27-93 97s32 FROM GE-NUCLEAR FUEL ids 91537552C4 PAGE 3/3 l Mr. H. J. Diamond 3 9/26/96 fuel From a flow standpoint, the GE13 fuelhas a slightly higher pressure drop than the i Gell fuel and would operate with slightly less flow through the fresh fuel than would be seen in an equilibrium core where all the fuel bundles are geometrically identical 'Ihis lower flow can cause more rods to be susceptible to boiling transition when the

uncertainties are statistically evaluated, thus increasing the calculated SLMCPR above an l equilibrium core.

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i Also, Peach Bottom 2 Cycle 12 is loaded aggressively with a high batch fraction to 1

achieve a two year cycle. With this loading it is easier to put more bundles in this core on i

MCPR limits than is generally possible for assumed equih'brium core designs. For the above reasons the Peach Bottom 2 Cycle 12 SLMCPR is higher than the generic 1.09

value.

i Very truly yours,

. Butrovich l FuelProject Manager i

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