ML20196E530

Requests NRC Concurrence W/Approach of Performing Cycle 7 LOCA Max Linear Heat Rate Calculations Using TACO3 in Lieu of Performing Confirmatory Calculation for Cycle 6 by 881230

ML20196E530
Person / Time
Site:	Davis Besse
Issue date:	12/02/1988
From:	Shelton D TOLEDO EDISON CO.
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
NUDOCS 8812120028
Download: ML20196E530 (2)

Text

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TOLEDO EDISON A Ca4rcr trurgy Cm Docket No. 50-346 DONALD C. SHELTON va n,-m.,

License No. NPF-3 #*"

Serial No. 1606 December 2, 1988 United States Nuclear Regulatory Commission Document Control Desk Vashington, D. C. 20555

Subject:

Calculation of LOCA Haximum Linear heat Rates at 4, 8, and 10 Foot Core Elevations i

Gentlemen:

License Amendment Number 123 (Log No. 2719), which approved the Davis-Besse Nuclear Power Station Cycle 6 Reload Report with associated revised Technical Specifications, was issued by the NRC on October 3, 1988. The Safety Evaluation issued with this Amendment by the NRC Office of Nuclear Reactor Regulation requires that Toledo Edison provide Cycle 6 confirmatory calculations for the LOCA maximem linear heat rates at the 4, 8, and 10 foot core elevations within six months after the start of Cycle 6. The Cycle 6 calculational results for the 2 and 6 Sot elevations vere provided in the

. License Amendment Request for the Cycle 6 Patload Report (Serial No.1516, dated May 18, 1988). The purpose of this letter is to address the need for the calculations at the 4, 8, and 10 foot elevations and to propose o alternative actions to be taken by Toledo Edison, i.e. performance of a complete reanalysis of LOCA maxim a linear heat rates for all elevations for Cycle 7 in lieu of performing cea?irmatory calculations for selected core j i elevations for Cycle 6.

l In April, 1987 B&V submitted a topical report to the NRC for an update to its fuel performance analysis code which is used in the LOCA Evaluation Model.  !

This code (TACO 3) is expected to be approved by NRC in December 1988. Since  !

q approval of this code is imminent, Toledo Edison proposes to perform the LOCA  !

j maximum linear heat rate reanalysis using this update to the evaluation model. l This analysis will include the 4, 8, and 10 foot core elevations for Cycle 7, .

rather than Cycle 6. In addition, Toledo Edison vould re-perform the 4

calculations at the 2 and 6 foot elevations for Cycle 7 using this nev a

evaluation model. <

5 Toledo Edison believes that it is preferable to perform the calculations for 1 Cycle 7 rather than reperforming confirmatory calculations for Cycle 6 for the following reasons. Toledo Edison understands that the overall intent if the  !

NRC request for these confirmatory calculations is to address tid combineo l"

! effects of the densification model and the revised cladding rupture, strain Ad ,l l THE TOLEDO EDSON COMPANY EDSON PLAZA 300 MADSON AVENUE TOLEDO, OH O 43652 l D 8G12120028 G81202 PDR ADOCK 05000346 P PDC

i Dockot No. 50-346 License No. NPF-3 Serial No. 1606 Page 2 and blockage models of NUREG-0630, "Cladding Svelling and Rupture Mcdels for LOCA Analysis". A limiting aspect of the NRC currently approved evaluation model is the effect of densification on the fuel temperature and pressure. It is noted that densification occurs early in fuel life and the effects of the densification penalty incurred are bounded by the assumptions used for the generic LOCA analysis after the new fuel has accumulated a burnup of 1000 MVD/MTU (approximately 25 effective full power days [EFPD]). After this burnup is reached, the generic maximum linear heat rates are retained for the remainder of the cycle.

The Cycle 6 calculations requested by the NRC Staff pertain only to che first approximately 25 EFPD and, as a result, the calculations vould not provide meaningful operational information six months following the startup of Cycle 6. Toledo Edison considers that performance of the calculations for Cycle 7 using the latest approved evaluation model vould result in more cost-beneficial use of both the Toledo Edison and the NRC Staff resources and would provide more important and useful information than additional confirmatory calculations for Cycle 6. Further, the calculations performed for Cycle 6 are not expected to be representative for Cycle 7 and subsequent cycles since the fuel to be utilized for Cycle 7 and beyond vill have a lover fuel pin pre-pressure.

Based on the above, Toledo Edison requests NRC Staff concurrence with its approach of performing Cycle 7 LOCA maximum linear heat rate calculations using TACO 3 in lieu of performing confirmatory calculations for Cycle 6. The terults of the Cycle 7 calculations foc the LOCA maximum linear heat rates at the 2, 4, 6, 8, and 10 foot core elevations vould be submitted to the NRC approximately 6 months prior to the beginning of the 6th refueling outage.

Toledo Edison requests your concurrence with this request by December 30, 1988.

a Additiaally, as discussed with A. V. DeAgazio on October 17, 1988, a typographical error has been noted on page four of the NRC safety evaluation for License Amendment No. 123. The sentence which reads, "The values of the maximum LHR's at the 4, 6, and 10 foot elevations for Cycle 6 vere calculated using methods acceptable ...", contains a typographical error in that the "6"

{

i should be an "8". As noted above, the Cycle 6 calculation results for the 6

( foot elevation was provided to the NRC in Serial No. 1516.

Should you require any additional information, please contact Mr. R. V.

Schrauder, Nuclear Licensing Manager, at (419) 249-2366.

Very truly yours,

/ [Vv GBK/dlm cct P. Byron, DB-1 NRC Senior Resident Inspector A. V. DeAgazio, DB-1 NRC Senior Project Manager A. B. Davis, Regional Administrator, NRC Region III