ML20133A737

Forwards Core Operating Limits Rept for Zion Unit 2 Cycle 15

ML20133A737
Person / Time
Site:	Zion File:ZionSolutions icon.png
Issue date:	12/27/1996
From:	Mueller J COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20133A740	List: ML20133A737 ML20133A743
References
NUDOCS 9701020086
Download: ML20133A737 (3)

Text

8 Commonwealth Edium Company l Zion Generating $tation l 101 Shiloh floulevard b

/. ion.11. N UN-2797 Tel H a7 7420H 1 I

December 27,1996 U. S. Nuclear Regulatory Commission

( Washington, D.C. 20555 Attention: Document Control Desk

Subject:

Commonwealth Edison Zion Nuclear Power Station Unit 2 Cycle 15 Reload and Core Operating Limits Report j NRC Docket Numbers 50-304

Reference:

Zion Technical Specification 6.6.1.F.2.4 l

Zion Station Unit 2 has recently completed its 14th cycle of operation and is currently j preparing for Cycle 15 startup. The purpose of this letter is to advise you of Comed's l review of the Cycle 15 reload under the provisions of 10CFR50.59 and to transmit the Core l Operating Limits Report (COLR) (included in Attachment A of this letter) for the upcoming

! cycle consistent with the referenced Technical Specification. ,

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! The Zion Unit 2 core, which consists of NRC approved fuel designs, was designed to operate i within approved fuel design criteria, Technical Specifications and related bases such that:

1) The core operating characteristics will be equivalent to or less limiting than those l l previously reviewed and accepted; or l 1

2) The re-analyses or re-evaluations have been performed to demonstrate that the limiting postulated UFSAR events which could be affected by the reload are within allowable limits.

All the core operating characteristics were equivalent or less limiting than those previously reviewed and accepted except for 3 items. The resolution of these 3 non-conforming items is l explained below to ensure the conclusions given in the UFSAR remain valid: j

! 1. The Non-LOCA transients were evaluated for en increase in maximum fuel temperatures due to the implementation of 1.0X IFBA fuel with an initial 100 psig helium backfill pressure. As a result of the fuel temperature increase, the safety analyses for the Loss of Flow and Locked Rotor events were reanalyzed.

For the Loss of Flow (UFSAR 15.3.1) and Locked Rotor (UFSAR 15.3.3) events, the I

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increased fuel temperatures resulted in increasing the transient heat flux conditions assumed in the DNB evaluations. These revised transient conditions were subsequently evaluated for DNB and found to meet the applicable DNB criterion used in the evaluation of these events.

The Condition IV Locked Rotor event was also analyzed based on the revised maximum fuel temperatures to demonstrate continued compliance with all applicable fuel temperature limits.

The results of the Locked Rotor analysis showed that all applicable fuel temperature limits  !

continue to be met with the increased fuel temperatures.

2. The use of less than 200 psig initial backfill IFBA will directly impact the large break LOCA analysis. In order to address the implementation of less than 200 psig initial backfill ,

IFBA, minimum rod internal pressure sensitivities were performed for Zion Station. In order to reasonably limit the lowest potential rod internal pressure that needs to be considered in the sensitivities, no lead rod burnup data below 50 MWD /MTU was considered. Thus, the evaluation assumes that full power will be reached after 50 MWD /MTU burnup for the lead rod. This evaluation produced a 24 F reduction in margin in PCT that will last until 1000 l MWD /MTU lead rod burnup. At 1000 MWD /MTU lead rod burnup, the rod internal pressure will increase such that IFBA fuel is no more limiting than non-IFBA fuel. Even with this  ;

PCT assessment, the limits of 10CFR50.46 continue to be met. I l

3. The reactivity versus rod position curve (SPIL item 1.1.4.a) calculated for Cycle 15 contains an extremely small non-conservatism when compared to the current limit for the first ,

4% of rod motion. The conservatism of the remaining portion of the curve offsets the small ]

deviation such that the licendng basis safety analyses remain applicable.

Consistent with past reloads, the reload licensing analyses performed for Cycle 15 utilized NRC-approved methodologies. The fresh fuel to be loaded in Cycle 15 consists of 76 VANTAGE 5 fuel assemblies without Intermediate Flow Mixer grids at a nominal 4.4 w/o enrichment. The cycle-specific power distribution limits for Cycle 15 are presented in the attached COLR.

Comed has performed a detailed review of the relevant reload licensing documents, the associated bases, and references. Based on that review, a safety evaluation was prepared, as j required by 10CFR50.59, which concluded that the reload presents no unreviewed safety i questions and requires no Technical Specification changes. The Zion On-Site review of the reload 10CFR50.59 has been completed.

Finally, further verification of the reload core design will be performed during startup testing.

The startup tests will be consistent with Technical Specifications and testing recommended in ANSI 19.6.1.

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If there are any questions regarding this matter, please contact this office.

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Sincerely, l

. IY.k)lp= = ~

J. H. Mueller  !

Site Vice President j Zion Station j i

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Attachment A: Core Operating Limits Report, Zion Unit 2 Cycle 15 cc:. A. B. Beach, Regional Administrator, Region 111

- C. Y. Shiraki, Zion Project Manager, NRR Acting Senior Resident Inspector, Zion Station

- Office of Nuclear Facility Safety - IDNS I

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