ML20070H288

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Responds to NRC Question on Cycle 5 Instrument Loop Uncertainties.Uncertainty Includes Allowance for Drift Based on Plant Experience
ML20070H288
Person / Time
Site: Calvert Cliffs Constellation icon.png
Issue date: 12/17/1982
From: Lippold W
BALTIMORE GAS & ELECTRIC CO.
To: Clark R
Office of Nuclear Reactor Regulation
References
NUDOCS 8212230312
Download: ML20070H288 (3)


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4 B ALTIMORE G AS AND ELECTRIC COMPANY P.O. BO X 14 7 5 B ALTIM O R E. M A R YL AN D 21203 NUCLEAR POWER DEPARTMENT CALVERT CLIFFS NUCLEAR POWER PL ANT LUS8Y. M ARYLA ND 20657 December 17, 1982 Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C. 20555 ATTENTION: MR. R. A. Clark, Chief Operating Reactors Branch #3 Division of Licensing

SUBJECT:

Calvert Cliffs Nuclear Power Plant Unit 2, Docket No. 50-318, DPR-69 Respons1 to NRC Question on Cycle 5 Instrumeat Loop Uncertainties Gentlemen:

NRC staff posed a question relative to the similarity of instrument loop uncertainties on Unit 2, Cycle 5 and Unit 1, Cycle 6. The technique for developing instrument loop uncertainties for those plant parameters affected by the Unit 1, Cycle 6 and Unit 2, Cycle 5 reload designs and safety analyses is identical for both units. In some cases the components in instrument loops are not identical between the Units. In all cases, the manufacturer's stated tolerances or tolerances more conservative than stated by the manufacturer for a component are used in developing an instrument loop uncertainty. The instrument loop uncertainty is added algebraically to the setpoint of the plant parameter used in the safety analysis and thereby yields the value stated in the Technical Specifications. The instrument loop uncertainty includes an allowance for drift based on plant experience. In some cases the value of the setpoint entered into the equipment is more conservative than specified in the Technical Specifications in order to ensure that unexpected drift rates and 00 8212230312 821217 PDR ADOCK 05000310 PDR p

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e Office of Nuclear Reactor Regulation December 17, 1982 Page 2 Should you have any questions, please contact us.

Very truly yours, W. J. Lippvid '

Nuclear Fuel Management WJL:fid ec: J. A. Biddison, Esquire -

G. F. Trowbridge, Esquire i

D. H. Jaffe - NRC R. R. Mills - CE R. E. Architzel- NRC/CC  !

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1 c- Office cf Nuclear React:r Regulation December 17,1983 -

Page 3 bec: R. E. Denton A. E. Lundvall, Jr, R. C. L. Olson J. A. Tiernan

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