ML20151X657

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PNO-77-123:on 770615,NSSS Notified Licensee of Nonconservative Error in Analysis for Small Break Loca. Millstone Point Unit 2 Currently Shut Down to Correct Main Station Transformer Problem.Media Interest Expected
ML20151X657
Person / Time
Site: Millstone Dominion icon.png
Issue date: 07/07/1977
From: Klingler G, Nolan F, Sniezek J
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE)
To:
References
PNO-77-123, NUDOCS 9809170201
Download: ML20151X657 (1)


Text

PRELIMINARY NOTIFICATIC'* L&ft July 7, 1977 C 08gg PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PH M This prelitninary notification constitutes EARLY notice of an event of POSSIBLE safety or public interest significance. The information presented is as initially received without verification or evaluation

_and is basically all that is known by IE staff on this date. ,

Facil ity: Northeast Nuclear Energy Company

  • Millstone Point Unit 2 Waterford, Connecticut (DN50-336) -

~

Subject:

NONCONSERVATIVE ERROR IN ANALYSIS FOR SMALL BREAK LOSS OF COOLANT ACCIDENT By letter dated June 15, 1977, the Nuclear Steam System Supolier (NSSS) notified the licensee of a nonconservative error in the anQsis for a small break loss of coolant accident (LOCA). Although a re-analysis has not yet been performed it is estimated by the NSSS and the licensee that the peak' fuel element clad temperature could increase by about 370'F, but would still be less than 2000 F following the LOCA. (10CFR50.46 limit is 2200 F).

The error was caused by improper inputs to the computer code for fuel peak linear heat generation rate (6% low) and high pressure safety in-jection (HPSI) flow rate (12% low). Combustion Engineering general plant inputs as opposed to plant specific inputs were utilized.

A similar error was made for the Fort' Calhoun facility (10% low on peak heat generation rate and 1~0% low on HPSI flow). This case has been re-

, ' analyzed with a resultant 372*F increase in peak fuel eler ent clad -

temperature. (Final value less than 2000 F)

Millstone Point Unit 2 is currently shut down to correct a main station transformer problem, (ReferencePNO-77-118) This small break analytical error will be resolved between the licensee and NRC prior to plant restart.

Mer'ia interest is expected because of close attention given to safety analyses related to nuclear power plants. The State of Connecticut has been informed. A press release is not planned by the licensee.

NRC, Region I, (Philadelphia) received notification of this occurrence by telephone from the Acting Unit Superintendent at 3:00 p.m., July 6, 1977. ,,

Contact,: GKlingler, IE x27451 FNolan, IE x27451 JSniezek, IE x27451 Distribution: TransmittedHSt/(: L3 Commissioner Kennedy C. C. Kammerer, CA G. F. Murphy, JCAE Commissioner Gilinsky S. J. Chilk, SECY 'H. H. Whiteside, SCNR

- H. R. Myers,.HCEE Transmitted: MNBBgjiM P Bldg /l', d SS Bldg ff;1 P L. V. Gossick, EDO E. G. Case, NRR C. V. Smith, NMSS S. H. Hanauer, EDO J. A. Harris, PA W. G. Mcdonald, MIPC Luge (MAIL) E. Volgenau, IE R. G. Ryan, OSP T. J. McTiernan, OIA Region s (fj l O H. K. Shapar ELD PRELIMINAR% NOTIFICATION 4-3070 9909170201 770707 D2"~t l PDR I&E '

PNO-77-123 PDR

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