ML20082P668

Submits Revised Response to NRC Bulletin 89-003, Potential Loss of Required Shutdown Margin During Refueling Operations. Listed Actions Will Be Taken to Ensure Adequate Shutdown Margin During Refueling Operations

ML20082P668
Person / Time
Site:	Davis Besse
Issue date:	08/28/1991
From:	Shelton D CENTERIOR ENERGY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
1975, IEB-89-003, IEB-89-3, TAC-M75420, NUDOCS 9109110001
Download: ML20082P668 (3)

Text

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. l CENTERDOR ENERGY Donald C. Shelton 300 Maison Avenue Voe Presdent Nuclear Tokdo. OH 43%2 0001 Davis flesse (419)249 2300 Docket Number 30-346 License Number NPF-3 t Serial Numbet 1975 August 28, 1991 United States Nuclear Regulatory Commission l

Document Cont 1ol Desk Vashington, D.C. 20$$$

Subjects Revised Response to NRC Bulletin Number 89-03: Potential '

Loss of Required Shutdown Margin during Refueling Operations (TAC No. H75420)

Gentlemen:

On November 21, 1989, the NRC Staff issued Bulletin Number 89-03

" Potential hoss of Required Shutdown Margin During Refueling Operations" (Toledo Edison Log Number 1-2181). The bulletin discussed that, with longer fuel operating cycles, the enrichment of reload fuel has been increasing which can result in the teduction of the shutdown margin during refueling operations involving intermediate fuel assembly positions. To assure that an adequate shutdown margin vill be I maintained during refueling operations, three actions were identified l by Bulletin Number 89-03: ,

1

1. Assure that any intermediate fuel assembly configuration (including control rods) intended to be used during refueling is identified and evaluated to maintain sufficient refueling boron concentration to result in a minimum shutdown mr.rgin of approximately five percent.

2. Assute that fuel loading procedures only allow those intermediate ,

fuel assembly configurations that do not violate the allovable  ;

shutdown margin and that these procedures are strictly adhered to. '

l 3. Assure that the staff responsible for refueling operations is trained in the procedures recommended in Item 2 above and understand the potential consequences of violat .ig these

! procedures. This training should include che fundamental aspects of criticality control with enriched fuel assemblies.

l 9109110001 910020 PDR ADDCK 05000346 O PDR

operavmg compomes Cieveland Dectoc mummateg g Toledo Edison

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Docket Number 50 346

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. License Number NPF-3 Serial Number 1975 Page 2 By letter (Serial Number 1770) dated February 13, 1990, Toledo Edison provided a response to NRC Bulletin Number 89-03 to address the three actions described above. In this initial response, Toledo Edison stated: (1) the refueling boron concentration calculation for the Davis-Besse Nuclear Power Station (DBNPS) assumes the final core configuration with no control rods installed and (2) during refueling operations at the DBNPS, scheduled intermediate fuel assembly -l configurations within the core are not utilized. The above appronch alleviated the necessity to perform a detailed analysis of all of the allowed interim core configurations to calculate the minimum required  ;

refueling boron concentration. The NRC staff found Toledo Edison's response to Bulletin Number 89-03 to be satisfactory and closed associated TAC No. H75420 by letter dated April 18, 1990 (bledo Edison Log Number 3221).

Although Toledo Edison's past practice has been that the refueling '

boron concentration calculation assumes the final core configuration vith no control rods installed, an acceptable alternate calculational method is to calculate the refueling boron concentration while considering control rod worth. Should Toledo Edison utilize this alternative calculational method, in which control rod vorth is considered, the calculational method vill ensure that the specified boron concentration maintains an overall core reactivity of K duringfuelhandling,withcontrolrodsandfuelassembliesaIkbme$0.95 d to be in the most adverse configuration (least negative reactivity) allowed by the core reload sequence. The K O.95 or less includes aonepercentAK/Kconservativeallowance18b,c' s,ertainties.

Regardless of the calculational method used, Toledo Edison vill only

• allow fuel and control rod movements that. result in configurations within the core that are bounded by the assumptions of the calculational method used to determine the refueling boron concentration.

Based on the above discussion, the actions delineated in NRC Bulletin Number 89-03 vill be addressed by using either calculational method to >

ensure that the minimum required shutdevn margin of 5 percent vill be maintained during refueling operations.

Should you have any questions or require additional information, please contact Mr. R. V. Schrauder, Manager - Nuclear Licensing, at (419) 249-2366. -

Very tr yours, Ifv '.

RhS/dlm Attachments cci P. H. Byron, NRC Region III, DB-1 NRC Senior Resident Inspector A. B. Davis, Regional Administrator, NRC Region III J. B. Hopkins, NRC/NRR DB-1 Senior Project Manager Utility Radiological Safety Board c _

. i_ _ , i

Docket Number 50-346

+'

• License Number NPF-3

• • Serial Number 1975 Enclosure ,

Page 1 l

REVISED RESPONSE TO NRC BULLETIN 89-03

" POTENTIAL LOSS OF REQUIRED SHUTDOVN HARGIN DURING REFUEb1NG OPERATIONS,"

FCA DAVIS-BESSE NUCLEA POVER STATION UNIT NUMBER 1 This letter is submitted in conformance with Section 182a, Atomic Energy Act of 1954, as amended, and 10CFR50.54(f) in response to NRC Bulletin Number 89-03, " Potential Loss of Required Shutdown Margin During Refueling Operations."

By: I '

C.' Shelton, Vice President Nucliar D.

Sworn and subscribed before me this 28th day of August, 1991.

kwhJ h 10b)

Notary Public, State of Ohio

. . . ,