ML20006E461

Responds to NRC Bulletin 89-003 Re Potential Loss of Required Shutdown Margin During Refueling Operations. Procedure DB-PF-00100, Fuel Handling Administration Revised to State Listed Info Under Caution

ML20006E461
Person / Time
Site:	Davis Besse
Issue date:	02/13/1990
From:	Shelton D TOLEDO EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
1770, IEB-89-003, IEB-89-3, IEIN-89-051, IEIN-89-51, NUDOCS 9002230227
Download: ML20006E461 (4)

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TOLEDO c "'

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> c__ ~ c DONALD C. SHELTON '

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Docket Number 50-346

. License Number NPF-3 0

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. Serial Number 1770 February 13.-1990' United States Nuclear Regulatory Commission Document Control Desk' Washington,-D. C. 20555 Subject.:-' Response to NRC Bulletin Number 89-03:

Potential Loss of Required.

f' Shutdown Margin During Refueling Operations Gentlemen:

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This letter is submitted pursuant to 10CFR50.54(f) in response to NRC Bulletin Number 89-03, " Potential' Loss of Required Shutdown Margin During Refueling'

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~0perations" (Log Number 1-2181 dated November 21, 1989)..On January ~29, 1990,.

Toledo ' Edison contacted Thomas V. Vambach, NRC Senior Project Manager -

. Davis-Besse Unit Number 1,'and discussed.the general status of Toledo. Edison's response and received verbal concurrence for a two week extension to.the 60-day response period.

Bulletin Number 89-03 discusses that with longer fuel-

.~ operating. cycles, the enrichment of reload fuel has been increasing which can result in-the' reduction'of the shutdown margin during refueling operations involving intermediate fuel assembly positions.- The Bulletin also indicates that although analyses'are performed to confirm that the refueling boron concentration is sufficient to maintain the required shutdown margin for the final core configuration, these analyses may not be sufficient to assure the shutdown margin vill be maintained for all intermediate fuel positions.

-To assure that adequate shutdown margin is maintained during refueling operations, thtee actions were identified by Bulletin Number 89-03: 1) any inter e diate fuel assembly configuration intended to be used during refueling must'be identified and evaluated to ensure maintenance of a sufficient

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-refueling boron concentration that results in a minimum shutdown margin of

.approximately five percent; 2) fuel loading procedures only allow those intermediate fuel assembly configurations that do not violate the allovable shutdown margin; and 3) that these procedures are strictly adhered to, and that ~ the staff responsible for refueling operations is trained in the fuel loading procedures and understand the potential consequences of violating these procedures.

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THE TOLEDO EDISON COMPANY EDISON PLAZA 300 MADISON AVENUE TOLEDO, OH!O 43652 6

9002230227 900213 Sh Thfu!

EDR ADOCK 05000346 Q

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t Lice' hse Number NPF-3 Serial Number 1770 Page.2-N

'During refseling operations at Davis-Besse, scheduled intermediate' fuel.

t assembly configurations within the core are not utilized.

Intermediate 7

. positions would only be used when a fuel assembly does not fit into its

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designated location for the cycle due to exposure induced bowing, tvisting, or other' unforeseen inabilities to. insert the fuel assembly in a normal manner.

.-Vhen this: occurs, the fuel' assembly may be set off to the' side within the core:

until a more appropriate time for final positioning. In accordanceLvith procedures, these-changes to the scheduled fuel movement sheets must be made

by a Reactor Engineer, and independently reviewed by a knowledgeable individual to ensure compliance with criticality. restrictions on fuel placement.

i Per Davis-Besse Technical Specification 3.9.1 the refueling W on concentration shall be based on the more conservative of the following reactivity conditions:-

c a) Either a K,ff.of.0.95 or less, which-includes a 1 percent ok/k conservative allowance for uncertainties, or b) A boron concentration of > 1800 ppm, which includes a 50 ppm conservative allowance for uncertainties.

The refueling boron concentration calculation for Davis-Besse assumes the final core configuration with no control rods installed.. Normally during a.

fuel shuffle only one or.two control rods are removed at any one time. Prior to nev. fuel receipt and subsequent movement, the fuel vendor performs a

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computer calculation to determine the refueling boron concentration.

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addition, Toledo Edison performs its own calculations based on vendor supplied L

core physics' data to confirm the fuel vendor's computer calculation.

l The present Davis-Besse core design requires the new fuel assemblies, each containing a burnable poison rod assembly, to be set in a checkerboard pattern. Therefore, from a criticality standpoint, the vorst possible single fuel. assembly misloading would be placing a new fuel assembly in the core with a new fuel assembly on each adjacent side.

As a part of-the vendor supplied

" Physics Operating Manual" calculations for the upcoming cycle.7, the above vorst case scenario was analyzed assuming zero B C concentration in the 3

burnable poison rod assemblies. Vith the refue1Ing boron concentration determined for the Cycle 7 core, the results of this analysis indicated a Keff of'less than 0.99 but greater thar 0.95.

The above misloading bounds all projected core configurations during refueling, from a criticality standpoint.

Based on the above results, proceGure DB-PF-00100, Fuel Handling

' Administration, has been revised to state:

CAUTION Do NOT place two or more new fuel assemblies side by side in the core, unless an analysis has been completed to ensure the boron concentration is sufficient to maintain Keff < 0.95.

(NRC Information Notice 89-51).

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'i' Licehse Number NPP-3 Serial Number 1770 Page 3 Prior _to commencement of the upcoming core refueling (Sixth Refueling Outage) similar vords vill be added to DB-PF-06300, Fuel. Load and Refueling Limits and Precautions.

In addition to the procedure modifications, training was conducted on'NFC Bulletin Number 89-03 for those individuals responsible for refueling operations. This training was completed on February 9, 1990..

Based on the above actions taken by Toledo Edison and those actions to be.

completed prior-to commencing the_ upcoming core refueling (Sixth Refueling Outage), Toledo Edison believes that the actions delineated in NRC Bulletin Number 89-03 have been adequately addressed and that the required minimum shutdown margin of:5 percent will-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 truly yours, l

JSL/ssg Enclosure

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P. M. Byron, DB-1 NRC Resident Inspector

.'A. B. Davis, Regional Administrator, NRC Region III T. V. Vambach, DB-1 NRC Senior Project Manager

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RESPONSE:TO NRC BULLETIN 89-03

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" POTENTIAL LOSS ~OF REQUIRED SHUTDOWN MARGIN DURING REFUELING OPERATIONS,"

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FOR I

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DAVIS-BESSE NUCLEAR POWER STATION UNIT NUMBER 1 e

f This letter is submitted in conformance with Section 182a, Atomic Energy Act

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of-1954~, as amended, and'10CFR50.54(f) in response to NRC Bulletin 89-03

" Potential Loss of Required Shutdown Margin During Refueling Operations."

i By:

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D. C. Shelton, Vice President Nuclear.

'Svorn and subscribed before me this 13th day of February, 1990.

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/ /ot Notary Public, State of Ohio EVELYN L DRESS s

NOTARY PUBUC, STATE OF0HO MyOccmin:o EviasMy23,1904 l

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