ML19296C214

Forwards IE Bulletin 80-04, Analysis of PWR Main Steam Line Break W/Continued Feedwater Addition. No Written Response Required

ML19296C214
Person / Time
Site:	San Onofre
Issue date:	02/08/1980
From:	Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
To:	Papay L SOUTHERN CALIFORNIA EDISON CO.
References
TAC-44652, NUDOCS 8002250399
Download: ML19296C214 (1)

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,,a WALNUT CREEK, CALIFORNIA 94596 February 8,1980 Docket No. 50-206 Southern California Edison Company P. O. Box 800 2244 Walnut Grove Avenue Rosemead, California 91770 A ttention: Dr. L. T. Papay, Vice President

.idvanced Engineering Gentlemen:

The enclosed IE Bulletin No. 80-04, is forwarded for action. A written response is required.

If you desire additional information regarding this matter, please contact this office.

Sincerely, fly C$ ~

M R. H. Engelken Director

Enclosure:

IE Bulletin No. 80-04 c c w/ enclosure:

R. Dietch, SCE J. M. Curran, SCE 800225"

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UflITED STATES SSINS No.:

6820 NUCLEAR REGULATORY COM!il5SION Accessions No.:

OFFICE OF INSPECTION AND ENFORCEI1ENT 7910250504 WASHINGTON, D.C.

20555 February 8, 1980 IE Bulletin No. 80-04 ANALYSIS OF A PMR I'AIN STEAt1 LINE BREAK "ITH CONTINUED FEEDUATER ADDITION Description of Circunstances:

Virginia Electric and Power Co. subnitted a recort to the Nuclear Regulatory Comission dated September 7,1979 that identified a deficiency in the original analysis of containment pressurization as a result of reanalysis of steam line break for North Anna Power Station, Units 3 and 4.

Stone and Webster Engineering Cornoration performed a reanalysis of centainment pressure following a main steam line break and determined that, if the auxiliary feedwater system continued to supply feedwater at runout conditions to the steam generator that had experienced the steam line break, containnent design oressure would be exceeded in approximately 10 minutes.

The long tern blowdown of the water supplied under runout conditions by the auxiliary feedwater system had not been considered in the earlier analysis.

On October 1, 1979, the foregoing infornation was provided to all holders of operating licenses and construction permits in IE Information Notice No. 79-24.

The Palisades facility did an accident analysis review pursuant to the information in the notice and discovered that with offsite power available, the condensate pumps would feed the affected generator at an excessive rate.

This excessive feed was not considered in the analyois for the stean line break accident.

On January 30, 1980, flaine Yankee Atonic Power Conpany inforned the IRC of an error in the main steam line break analysis for the !!aine Yankee plant.

During a review of the nain steam line break analysis, for zero or low power at the end of core life, the licensee identified ar morrect oostulation that the startup feedwater control valves would rer asitioned "as is" during the transient.

In reality, the startup feec control valves will rano to 805 full open due to an override signal ret from the low steam generator pressure reactor trip signal.

Reanalysi-the event shows the opening of the startup valve and associated high feedwater addition to the affected stean generator would cause a rapid reactor cooldown and resultant return-to-power, a condition outside the plant design basis.

Actions to be Taken by the Licensee-For all pressurized water power rea DUPLICATE DOCUMENT reactors listed in Enclosure 1:

Entire document previously 1.

Review the containment pressur entered into system under:

potential for containment over No. of pages: