ML20135D772

Non-proprietary, Evaluation of Limerick Initial Core Channels for Re-Use on Ex-Shoreham Fuels Bundles

ML20135D772
Person / Time
Site:	Limerick
Issue date:	04/30/1996
From:	Higgins R, Marrotte G GENERAL ELECTRIC CO.
To:
Shared Package
ML20135D761	List: ML20135D758 ML20135D772
References
NUDOCS 9612100132
Download: ML20135D772 (6)

Text

- ..- . - _. .- - - _ - _ . - . . . . _ - _ - - . . . . . . . . - . . - . - . _ . .

1

)

, . i

)

i I

J l

Evaluation i

of l t

l Limerick Initial Core Channels  !

l i for j Re-Use on ex-Shoreham Fuel Bundles 1

i I

1 Prepared by l G. N. Manotte/R. P. Higgins General Electric Company April 1996 I

4 9612100132 961202 PDR ADOCK 05000352 p PDR

Important Notice Regarding l

Contents of This Report

1 2

Please Read Carefully k

he onh / undenakings of GE respecting information in this repon are contained in the

'l

{ agreement between PECO Energy Company and General Electric Company for Nuclear Services effective July 1,1994 and nothing contained in this repon shall be construed as changing said agreement. He use of this information for any purpose other than that for which it is intended, is not authorized; and with respect to any such unauthorized use, neither l GE nor any of the contributors to this repon makes any representation or warranty (express or implied) as to the completeness, accuracy or usefulness of the information contained in this repon or that such use of such information may not infringe privately owned rights; no do

they assume any responsibility for liability or damage of any kind which may resuk from such c

use of such information.

l 1 l I

4 l

i

)

l I

ii

Evaluation of LimerickInitial Core Channels l for Re-Use on ex-Shoreham Fuel Bundles  ;

l .

Abstract His report provides the resuhs of analyses that support the re-use oflow exposure Limenck initial core channels on ex-Shoreham fuel bundles as permitted within specified constraints.

, Introduction l A study has been performed to determine the acceptability ofre-using Limerick initial core channels on ex-Shoreham fuel bundles in peripheral celllocations at Limerick Unhs 1 & 2. '

His study utdized the re-use restrictions provided by PECO Energy and SIL 320 to establish -

speciSc re-use sequences. Potential channel-control rod interference and thermallimit impact  !

due to cell average bow were evaluated. His study assumed actual channel exposures for the imtial cycle ofuse and estimated exposures for the following two cycles ofuse.

He following key assumptions form the basis of this study:

Channels that were located on the periphery during initial core use, will be located one row in during the initial re-use cycle.

Channels that were used in Linwrick Unit 2 initial core control cells will be used on the periphery for both re-use cycles.

No more than two channels in their second re-use cycle will reside in an individual  !

cell.

He expected channel total exposure is less than typical single-bundle lifetime l

channel exposures which are taken to be approximately 35 GWd/ST. Herefore, '

the re-use oflow exposure channels may be considered within single bundle lifetime criteria.

Conclusions e

SIL 320 and SIL 320 Supplement I recommendations (as modified) are applicable to the use of Limerick initial core channels on Shoreham 3:el bundles for two additional 24 month cycles ofoperation.

De planned channel re-use is acceptable with respect to channel-control blade interaction.

Channel bow associated with re-ua:.; channels will not impact the calculated SLMCPR.

He use oflow exposure initial core Limerick channels on ex-Shoreham fuel in low power regions of the core is not expected to resuh in any impact on thermal margins.

Channel bow will impact the ex-Shoreham bundles' local peaking factors.

t I

1

~

. l Channel Bow-Control Blade Interaction Evaluation Introduction  !

i ne use oflow exposure channels from the Limerick Units 1 & 2 initial cores together with Shoreham fuel bundles is evaluated for use in the peripheral cens ofLimerick Units 1 & 2. i ne re-use of these channels is analyzed assuming the following:

e ne re-use channels received their initial exposure either in an interior control ceu or in a peripheral ceH, with a maxinnim core average exposure of 9,810 mwd /ST. Ref 1 & 2.

, e ne first re-use cycle will go to a core average exposure of17,445 mwd /ST. Ref 3.

He second re use cycle will go to a core average exposure of15,662 mwd /ST. Ref 4.

He first re-use cycle for channels which were initially in an interior control cell will be on the periphery.

The second re-use cycle for channels which were innially in an interior control cell will be on the periphery.

He first re-use cycle for channels which were initially on the periphery will be one row in from the periphery. l e I The second re-use cycle for channels which were initially on the periphery will be on the periphery, or one row in from the periphery.

Evaluation Method l

GE Proprietary Information Removed i

References

1. 23A1755 Rev. O, " Limerick 1 Cycle 1 Summary Report"

2. L11-00357 Rev. O," Limerick 2 Cycle 1 Summary Report".

4

3. Fax from Jim Tusar to Sten Akerlund dated 9/1/95, containing bundle average exposures for LGS-1 cycle 7.

4. Fax from Tun Tusar to Sten Akerlund dated 11/21/95, containing bundle average i exposures for LGS-2 cycle 4.

2 i

Impact on ex-Shoreham Fuel Thermal Margins Purpose ne purpose of this analysis is to assess the potential impact of these re-used channels on

, thermal margins and on the safety limit MCPR.

Dermitions l

1 Bow, or cell average bow, refers to the average amount ofbow in the four fuel bundles surrounding a control blade. Bow generally peaks near the middle nodes of the bundle and is zero at the top and bottom ends. .

i Assumptions i It is assumed that the ex-Shoreham fuel will continue to be loaded only in low power regions I (i.e. on the periphery or one row inward).

Fuel Designs Two bundle types of ex-Shoreham GE6 fuel are being used in Limerick Units 1 and 2. One 235 bundle 2

has an initial average enrichment of 2.19% U , the other has an enrichment of1.76%

U ". Each bundle consists of three different enriched lattice designs ud one natural uranium lattice design. Rese bundles may be equipped with either 80 mil or 100 mil thick channels.

i Thermal Margin Impact ofIncreased Bow l GE Proprietary Information Removed

)

3

i. .

~

4 l Channel Re-Use Scenario i A study of possible channel re-use sequences was made based upon the current Limerick 2 i Cycle 4 and a preliminary Cycle 5 core loading pattems. His study showed that for the 260 ex-Shoreham bundles,120 will be on the periphery for two operating cycles, 36 will be one row in for two operating cycles and the remainder (104) will be one row in followed by the '

periphery. His scenario is presented as one possible channel use scenario and is not intended  ;

' to present a scenario that must be explicitly followed by PECO Energy. Speci6c guidelines to be followed were provided by PECO Energy as inputs to this analysis.

Limerick 2 Cycle 5 (limerick 1 Cycle 8)  :

! A total of 88 new ex-Shoreham bundles are planned for use. 48 bundles are being placed one row in and the remainder on the periphery. These 48 bundles need to utilize channels from s

the Limerick 2 initial core natural bundles with the least exposure. He 48 bundles consist of j

40 2.19% enriched and 81.76% enriched bundles. He 40 peripheral bundles need to utilize i the lowest exposure Limerick 2 initial core control cell channels. He 40 bundles include 16 3

2.19% enriched and 241.76% enriched bundles.

{ He core loading for this cycle includes 80 once burned ex-Shoreham bundles with TSA q cnannels. 52 of these bundles are planned to be located on the periphery. His leaves 40 1

locations for 40 fresh ex-Shoreham bundles with re used channels.

} IJmerick 2 Cycle 6 A total of 88 once burned ex-Shoreham bundles with re-used channels may be used during this cycle. Rese may be distributed in the core with 36 one row in and 52 on the periphery.

A total of d4 fresh ex-Shoreham bundles are planned for use. 44 may be placed one row in and 40 may be on the periphery, ne 56 fresh 2.19% bundles may be positioned with 40 one j row in and 16 on the periphery. He 281.76% fresh bundles may be positioned with 24 on the periphery and 4 one row in. He bundles placed one row in should utilize the remainmg

! Limerick 2 natural bundle channels.

Ilmerick 2 Cycle 7 (Limerick 1 Cycle 9)

A total of 84 once burned ex-Shoreham bundles with re-used channels may be used during j this cycle. Rese bundles will be located on the periphery.

i i

I 4

4

_ _ _ _ __- _ . .. . _ __