ML20090E305

AO 73-11-12:during Review of Spring 1973 Refueling Outage Tech Spec Update,Discrepancy Noted in Pressure Setpoint Trip of Recirculation Pumps.Caused by Design Error.Design Will Be Changed

ML20090E305
Person / Time
Site:	Nine Mile Point
Issue date:	11/30/1973
From:	Schneider R NIAGARA MOHAWK POWER CORP.
To:	Skovholt D US ATOMIC ENERGY COMMISSION (AEC)
References
A-73-11-12, A0-73-11-12, NUDOCS 8303140591
Download: ML20090E305 (2)

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% . s NIAGARA MOH AWK POwtR CORPORATION NIAGARA MOHAWK .) g 4

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6 g1 November 30, 1973 O A

'C7 Mr. Donald J. Skovholt Assistant Director For Reactor Operations

[h Division of Reactor Licensing U. S. Atomic Energy Commission Washington, D. C. 20545

Dear Mr. Skovholt:

Re: Provisional Operating License: DPR-17 Unusual Event 73-11-2 Docket No.: 50-220

, x In accordance with Section 6.6. b 2 of the Nine Mile Point Nuclear Station, Unit #1 Technical Specifications, the following information is forwarded concerning an unusual event-occurring at the Nine Mile Point Nuclear Station, Unit #1.  ;

During the Spring 1973 refueling outage, the circuitry to cause the trip of all' I recirculation pumps upon reacliing a pre-established reactor pressure was installed c=

in accordance with reviewed and approved design change drawings. The requirement ~hF for this change is discussed in detail in the " Technical Supplement To Petition For ~.

Conversion Fron Provisional Operating License To Full Term Operating License" ,

page IV 39 - IV 47. w A review of the existing Technical Specification with regard to updating 4was conducted this Fall, when a discrepancy was noted in the pressure set point trip of the recircu-o so lation pumps for the Analysis of Transients without scram. A thorough review by the' '

Site Operating Review Committee revealed that the pumps will be tripped at 1080 psig rather than the intended 1150 psig as stated in the above mentioned document. The- .

offect of lowering this set point has no detrimental effect on the Analysis of- f' Transients.without scram. Ilowever, it does have'an adverse effectJon the marginD , ' "

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between peak pressure reached in a transient involving scram with turbine' trip and! ',

failure of the bypass! system and the lowest safety valve setting. Althoughino;safetyL w limits are reached, the degradation of the pressnre margin is of concern. - General '. 4 Electric Company _has concluded that existing power operation is permissible with.no. ^

infringement on the safe operation of. the plant or safety of the general public.: '

.!!owever, as stated in my letter of November 30, 1973, to Mr. Giambusso, the trip-of.

recirculation pumps ~on high react 6r pressure is being deleted from-tne protection system circuitry;to prevent acsumed aggravation of other transients. ~

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sc., A THr.., Donald-J..Skovholt

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lr. . ? November 130,.1973-

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[The.GeneralElectridCompanyiscompletingareviewof.safetyanalysis-todeternine

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- " ~ " the'effect -of this new parameter on performance on transient condit' ions. When their d # review'is1 complete, design changes will be fornulated, reviewed, approved:and'

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Very truly yours,- ,

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, ORIGINAL SIGNED BY'R.R.SCllNEIDER

[,~ "~i 9 ' 11. . R. - Schneider Vice l'rcsident ;- Electric Operatioas

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'cc Mr. James' P. O'Reilly.

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