ML19338F784

Requests Recalculation of Boron Dilution Event for Cold Shutdown W/Rcs Drained to half-pipe Level & Cold Shutdown W/No Reactor Coolant Pumps Running.Reanalysis & Commitment to Revise Procedures Should Be Completed within 60 Days

ML19338F784
Person / Time
Site:	Point Beach
Issue date:	09/30/1980
From:	Clark R Office of Nuclear Reactor Regulation
To:	Burstein S WISCONSIN ELECTRIC POWER CO.
References
NUDOCS 8010270249
Download: ML19338F784 (3)

Text

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3, hh5di;@j,4! dU' chi.I III.I iJUE i Bo SEp W sS0 Docket Nos. 50-266 and 50-301 Mr. Sol Burstein' Executive Vice President Wisconsin Electric Power Company 231 West Michigan Street Milwaukee, Wisconsin 53201

Dear Mr. Burstein:

During a recent review of the safety analysis for postulated uncontrolled boron dilution events fbr Millstone Unit 2, the licensee fbund that some non-conservative assumptions had been made for shutdown modes. An extract of the Licensee Event Report is enclosed for your inkrmation (Enclosure 1).

Our review of this matter indicates that there are two plant conditions which may not have been conservatively considered with respect to inad-vertent boron dilution:

1.

Cold shutdown with the reactor coolant system drained to the "Falf-pipe" level (reduced RCS volume).

2.

Cold shutdown with no reactor coolant pumps running (an effective reduced RCS volume).

A review of your FFDSAR (Section 1411.5) indicates that a boren dilution event under the:e specific plant conditions is not addressed.

Based on the fbregoing, you are requested to:

1.

Recalculate the baron dilution event fbr these plant conditions, l

using the reduced RCS volume and 15-minute criteria contained in the Standard Review Plan Section 15.4.6 (Enclosure 2).

(Ncte that unless a reactor coolant pump is continuously operating, the conservative volume to be used is the drained down ("l/2-pipe") volume of the RCS plus that of the residual heat removal system and connecting piping.)

2.

Provide a commitment to revise appropriate plant pmcedures as necessary to insure that the correct shutdown margin is maintained.

3.

Propose revised Technical Specification changes as necessary.

The reanalyses and commitment to revise plant pmcedures as necessary should be completed within 60 days. Proposed Technical Specification char; = - ha=1d ha = ' ::t fia== =sithin 1510 d===

Mr. Sol Burstein Wisconsin Electric Power Company Please contact us if pu have any questions regarding this matter.

Sincerely, gginai sii;"*d DY*

Robert A. Clark, Chief Operating Reactors Branch #1 Division of Licensing Enciosures:

1.

Millstone LER 80-05 2

SRP 15.4.6 cc: w/ enclosures See next page DISTRIBUTION Docket Files 50-266 and 50-301 NRC PDRs (2)

Local PDR TERA NSIC NRR Reading ORB 3 Reading D. Eisenhut T. Novak R. Clark C. Trammell P. Kreutzer I&E (3)

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September 30, 1980 Docket Nos. 50-266 and 50-301 Mr. Sol Burstein Executive Vice President Wisconsin Electric Power Company 231 West Michigan Street Milwaukee, Wisconsin 53201

Dear Mr. Burstein:

During a recent review of the safety analysis for postulated uncontrolled boren dilution events for Millstone Unit 2, the 1icensee found that some non-conservative assumptions had been made for shutdown modes. An extract of the Licensee Event Report is enclosed for your information (Enclosure 1).

Our review of this matter indicates that there are two olant conditions which may not have been conservatively considered with respect to inad-vertent boron dilution:

1.

Cold shutdown with the reactor coolant system drained to the " half-pipe" level (reduced RCS volume).

2.

Cold shutdown with no reactor coolant pumps running (an effective reduced RCS volume).

A review o'f your FFDSAR (Section 14.1.5) indicates that a baron dilution event under these specific plant conditions is not addressed.

Based on the foregoing, you are requested to:

1.

Recalculate the boron dilution event for these plant conditions, using the reduced RCS volume and 15-minute criteria contained in the Standard Review Plan Section 15.4.5 (Enclosure 2).

(Note that unless a reactor coolant pump is continuously operating, the conservative volume to be used is the drained down ("1/2-pipe") volume of the RCS plus that of tne residual heat removal system and connecting piping.)

2.

Provide a commit:nent to revise approcriate plant procedures as necessary to insure that the correct shutdown margin is maintained.

3.

Propose revised Technical Specification changes as necessary.

The reanalyses and commitment to revise plant procedures as necessary should be completed within 60 days. Proposed Technical Specification enanges should be subnitted to us within 180 days.

Mr. Sol Burstein Wisconsin Electric Power Company '

Please contact us if you have any questions regarding this matter.

Sincerely, Robert A. Clark, Chief Operating Reactors Branch fl Division of Licensirg Enclosures :

1.

Millstone LER 80-05 2.

SRP 15.4.6 cc: w/ enclosures See next page i

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Mr. Sol Surstein ff Wisconsin Electric Power Company cc: Mr. Bruce Churchill Esquire Mr. Williar. Guldemond Shaw, Pittman, Potts and Trowbridge USNRC Resident Inspectors Office.

1800 M Street, N.W.

, 6612 Nuclear Road Washington, D. C.

20026 Two Rivers Wisconsin 54241 JosephMann-L5brary 1516 Sixteenth. Street Two Rivers', Wisconsin.54241

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Mr. Glenn A. Reed, Manager Nuclear Operations Wisconsin Electric Power Ceepany Point Beach Nuclear Plant 6610 Nuclear Road two Rivers, Wisconsin 54241 Walter L. Myer Tcwn Chairman Town of Two Creeks Route 3 Two Rivers, Wisconsin 54241 Ms. Kathleen M. Falk General Counsel Wisconsin's Environmental Decade 302 E. Washington Avenue Madison, Wisconsin 53703 Director, Technical Assessment Divisien l

Office of Radiation Programs (AW-459)

U. S. Environmental Protection Ag'ency Crystal Mall #2 Arlington, Virginia 20460 U. S. Environmental Protection Agency Federal Activities Branch Region Y Office ATTN:

EIS COORDINATOR 230 S. Dearborn Street Chicago, Illinois 60604 Chai rman Public Service Connission of Wisconsin Hill Farms State Office Building Madison, Wiseonsin. 53702 I

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ATTACFJiENT 1 L5R 20-05/17-0 Millstone Unit 2 Oc:ket No. =.. 3;..o v-Event Descri tion During a review cf the safety analysis it was disc:ve. ed that an -

in:orrect assumption had been made in the analysis Of the bcr:n dilution event.

The analysis of this event while in Mede 5 (:cid shutdcwn) had assuced a full reacter c:clant systa., and a 15 shutdewn margin.

Tnis resulted in a time to bec:me critical of 20 minutes which satisfied the requiremen: for the 15 minute maximum time assumed for the cperators to re::gni:e the situatien and take action.

However, the analysis had net ::nsidered the fact that c;aration is pessible '4ith the reac r c:clent sys:em drained to the centerline cf the hat leg.

Including this reduced volume of reacter ceciant to be cilute: in the analysis resuits in a time to reach criticality cf less than 15 minutes.

Cause Descri::ica and Corrective Actions m

At the reduced syste volume the time t: reach criticality during the Pede 5 dilution even: wculd have been less than the 15 minu as allowed for the cperator to te nina:e the even:.

5y in:reasing :he requi.ed shutdown cargin in Mede 5 to 2t, a time to c.-iticality of greater than 15 minutes is reestablished.

Until the necessary Technical Specification changes can be 2;;r:ved, tne uni will administratively caintain a shutde 9 margin in ax:sss of 2% in Mcde 5.

In the pas: it has been s andard pra::fes :: maintain :ne Mede 4 shutdown bcr n cen:entration requiremenc hile in F.cde 5, v.hich

rivides reas

nable assurance tha: a greater than 2% shutscwn margin has been main ained during previ:us Mece 5 c;cratien.

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D U 3 ;7 R m EV-Lt: -ated =tter can de added := the rea:::r ::ala.: syste::, via the :hemical volume and g

=n*. 01 syste: ( */CS), : increast c:rt rea::ivity. This ay happen inadverter.:!y, because tE cf :e et.:r e:--:r er 705 :.alfun::icn, and cause an unwante: increase in rea:tivity and E

e a de: ease in shutd:.n margin.

he :; erat:r must s.:: this un: Tanned diluti n bef:re tne sa:t.do. =a ;in is eliminated..!!nce :ne se:ven:ss :f events :nat may :::ur ce:end :n eg l L.

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a:i:n (aster.atic ::nt :1 and =anual.::es), h: stan:ty, tnd : id shut:: m.

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lytical ecdel, and predicted :=r.sequen:es f the event.

Tr.e se:uence =f events described in the a: lican 's safety analysis re: r: ISAR) is e<1e --d by bc.h the RSS and 113*53. The R$3 revie.er ::n=entrates en :ne need for the ta: :r :-:: : icn system and :?.e :: erat:r a: icn e:uired :: sa:ure and aintain :ne rea:::e

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