ML20213D165

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PNO-I-80-39:nonconservative Assumption Made in Analysis for Boron Dilution Accident Due to C-E Not Assuming RCS Water Vol Less than Total Vol of Sys.Could Cause Criticality After 10 Minutes of Rated Dilution Instead of 15 Minutes
ML20213D165
Person / Time
Site: Millstone Dominion icon.png
Issue date: 03/12/1980
From: Brunner E, Keimig R
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
References
PNO-I-80-039, PNO-I-80-39, NUDOCS 8004240234
Download: ML20213D165 (1)


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PRELIMINAAY NOTIFICATION _.

h c Date: March 12, 1980 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE--PND-I-80-39 l

lhispreliminarynotificationconstitutesEARL,Y_ notice _of._eventsofPOSSIBLE l tafety or_public 1_nterest sign 1Ticance. The information presented is as initially received without verification or evaluation and is basically all that is known by IE starf on this date. ~

Facility: Northeast Nuclear Energy Cctnpany '

Millstone Nuclear Station Unit 2 (DN 50-245) 4 __

Waterford, Connecticut 2' 1

Subject:

NONCONSERVATIVF ANALYSIS OF BORON DTLUTION ACCIDENT S

m [8 e-3 The licensee discoycred that a nonconscrvative assumption had been made3n Me h]

analysis for boron dilution accident. ' The analysis performed by the rn i Steam System Supplier (Combustion Engineering) had not assumed a tneCng) ant Reac$ffSeiw>

. System water volume less then the total volume of the system. ,--.

MaintenaR e W '

surveillance activities during a plant shutdown could require the Reactp7 Onnlant. F System to be drained to the mid-plane of the reactor coolant hot leg with ntinimum vah in the shutdown cooling system. Assuming that the minimun technical specification requirement of 17. A{'/K, criticality could occurnitial shutd after 10 minutes of rated dilution instead of the previously analysed 15 minutes.

At present Mille. tone linit 2 is operating at 1007. power, therefore, there are no safety concerns for this plant at this time. The licensee is evaluating corrective action which may involve increasing the minimum specified shutdown margin. The nucloor system supplier is also pursuing the matter and has indicated that not1fication will be made to other customors. .

Media i-te es+ is possible because of sensitivity to nuclear power plant problems.

lhe State of Connecticut has been informed. A press release is being made by the licensee. No press release by NRC is planned at this time. RI will respond to news media inquiries.

This pH is issued for infornation and because of potential gerieric implications at other plants with Combustion Engineering reactor system. The NRC Resident inspector received notifiedtion of the occurrence from the Unit Superintendent at 3:15 p.M.,

on March 11. 1980.

This infonmillon is current as of 4:45 p.m. M,arr.h 11, 1980, .

CONTACT: R. R. Keimia, 488-1252 E. Brunner, 488-1240 00 4O23

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PR'EO HINARY NOTIFIUAliON Region I Fom 83a (Rev. January 1980)