ML20062K017

Notifies That NRC Review of Licensee Safety Analysis for Postulated Uncontrolled Boron Dilution Events Indicates Nonconservative Plant Conditions.Recalculation of Boron Dilution & Tech Spec Mod Recommended.W/Supporting Info

ML20062K017
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
TAC-43514, TAC-43515, NUDOCS 8011190059
Download: ML20062K017 (4)

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NUCLEAR REGULATORY COMMISSION E

WASHINGTON, D. C.,20555 5

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September 30, 1980

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l Docket Nos. 50-266 and 50-301 Mr. Sol Burstet.1 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 for Millstone Unit 2, the licensee 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 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 " 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.S) indicates that a boron 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 15.4.6 (Enclosure 2),

(Note 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 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 procedr es as necessary should be compl eted within 60 days.

Proposed Technicul Specif' cation changes should be submitted to us within 180 days.

80111'90059 THIS DOCUMENT CONTAINS of P0OR QUAUTY PAGES i

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

Sincerely, l(Jjnl E

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

1 Millstone LER E0-05 l

2.

SRP 15.4.6 cc: w/ enclosures See next page

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Mr. Sol Burstein ff Wisconsin' Electric Power Company cc: Mr. Bruce Churchill, Esquire Mr. Wi.lliam Guidemond

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Shaw, Pittman, Potts and Trowbridge USNRC Resident Inspectors Office; 1800 M Street, N.W.

, 6612 Nuclear Road Washington, D. C.

20036

,Two' Rivers, Wisconsin 54241 Joseph Mann.L5brary 1516 Sixteenth. Street

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Two Rivers, Wisconsin.54241 Mr. Glenn A. Reed, Manager Nuclear Operations Wisconsin Electric Power Company Point Beach Nuclear Plant 6610 Nuclear Road Two Rivers, Wisconsin 54241 Walter L. Myer Town 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 Medison, Wisconsin 53703

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Director, Tech'nical Assesscent Division 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 V Office ATTN:

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

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ATTACHMENT 1

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LER 20-05/lT-0 Hillstone Unit 2 Docket No. 50:335 Event Descriotion During a review of the safety analysis itiwas discovered that an -

incorrect assumption had been made in the analysis of the boron dilution event.

The analysis of this event while in Mode 5 (cold shutdown) had assuced a full reactor coolant system and a 1% shutdewn nts resulted in a time to beceme critical of 20 minutes margin.

i which satisfied the requirement for the 15 minute maximum time assumed for the cperators to raccgnte the situation and take action.

However, the analysis had not considered the fact that operation is possible with the reactor ceciant system drained to the centerline cf the hot leg.

Including this reduced volume of reactor coolant to ha diluted in the analysis resuits in a time to reach criticality of less than 15 minutes.

Cause Descricticn and Corrective Actions At the reduced system volume the time te reach criticality during the Mode 5 dilution avent would have been less than the 15 minutes allowed for the cperator to teminate the event.

By increasing the required shutdcwn cargin in Mode 5 to 2%, a time to criticality of greater than 15 minutes is reestablished.

l'ntil the necessary Technical Specification changes can be appr:ved, the unit will administrative 1y maintain a shutdewn margin in excess of 2% in Mede

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In the past it has been standard practice t; maintain the Mede 4 shutdown boron concentration requirement while in Mode 5, which provices reasonable assurance that a greater than 2% shutdown margin has been maintained during previcus Mode 5 operatien.

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c::t.-ci syste: (CYC5), to increase cere reactivity. This c.ty hap;en inadvertently, because j

cf c;-erater er cr or CVCS calfun: icn, and cause an unwanted increase in rea:tivity and a decnase in shutdown margin. The c;trater must step this un:lanned dilution before the

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]l c:nditi ns at the time of the ut;1anned dilutien, such as refueling, starta:, power

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nd:"2 c:e-atten (aute.,matic cent ci and r.anual c.: des), het staneby, and cold shut:r.m.

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y zu-r Tr.e revie.' cf p:stulated caderat:r dilutien eve.ts considers causes, initiatin; eve nts, tre se:vence of events, the analy-ical model, the values Of parameters uset in the ana-k'.

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Tr.e se:vence cf events des:ribed in the a;;,licant's safety analysis re; rt (SAR) is f

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ir. a stfe c:ndition. The !! CSS reviewtr con:entrates en :ne instrumentatier, and centrols ti;e:ts of the se:ven:e described in the SAR te evaluate whether' ?.he rea:::t and plant f

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centrols and instruser.tation syste=s will functica as assumed in

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II. A:CI?TANCE CRITERIA

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Tne general cbje::ive of the review of c,:.derater dilutica events is to confim that g

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either of the following c:nditiens are met:

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'The consecuences of these events are less severe than the consequences of ancther f

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transient that results in an une:nt :lled in:rease in reactiv,ity and has the same

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anticipated frequen:y classification.

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The plant res;cnds :: the events in such a way that the criteria recarding fuel

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ine specific criteria for :noderater dilu:f on events are:

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P. essure in the rea:::r c clant and r. tin steam systems should be maintained below E

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Criterien 1 cf SR? 4.a is satisfied th-: ugh ut the transien:.

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T; Such incidents will not senerate a r.:re sericus ;1 ant ::ndition without other faults E

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The applicant's analysis of coderator dilution events sh:uld be ;:rfer=:d using an

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the reviewer requests an evalcati n by'C?5..

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All of the follodng plant initial conditiens sh:uld be c:nsidered in the analysis:

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refue'.ing, startup, power c;eration (aute:atic centrol and =anual c: des), het

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Be parameters and assu=pti:ns used in the analytical e,: del sh:uld be suitably con-

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s erva tive. The following values and assu:;; ions are considered acceptable:

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Fcr analyses durin; ;:.er ::eratien, the initial p:-er level is rated cutput is a.

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measurement uncertainty.

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The boren dilutien is assu=ed to oc:ur at the e.aximum possible rate.

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most limiting c::bination of moderater tem;trature cesfficient, veid coefficient, jg 0:ppler c: efficient, axial ;: er ;r: file, and radiai power distribution. This 55

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vai es will be used in ne analysis, anc the revie.<er sh:uid ::::are taase 7 :ne limitin; g

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Mr. John T. Collins, Denut'. Director U. S. Suclear Regulatory Coccission c/o Three Mile Island Nuclear Station Middletown, Pennsylvania 17057

Dear Sir:

Three Mile Island Nuclear Station, l,nl:

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Operating License No. DPR-73 Decke: No. 50-320 Status of Proprietarv Documente Two proprietarv d ec ur.en t s relatinc to the EPICOR Radraste F"Ete wer-f orwa rde :' to the TC as follows:

TLL 3 9, cared 7/16/50

" EPIC 0F, II Resin Irradiation ?atc" TLL '::. dat e d 9 '0 5 /8 0 "Evaluat ion of EP ICnR II

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Deter-ination of ';RC acceptance of these documents as beinc croprietar.

has net been received.

It is recuested the ':RC provide a status of, and a date when thi.a deternination will be made.

The status of TL 3 0 i:

c' particular i. tere s: since this letter has been in :

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TMI-2 Corrsspondenem (bec list)

Mr. E. L. Blake, Jr.

Dr. Steven Long, Director Sh!.w, Pittman, Potts, & Trowbridge Power Plant Siting Program 1800 M Street, N.W.

Department of Natural Resources W2thington, D.C.

20036 Tawes State Office, Building B-3 580 Taylor Avenue Mr. A. S. Dam Annapolis, Maryland. 21401 Burns and Roe, Inc.

650 Winters Avenue Mr. Thomas Gerusky, Director Paramus, New Jersey 07652 Bureau of Radiation Protection PA Department of Environmental Resources Mr. T. F. Hartley, Jr.

Fulton National Bank Building Marsh and McLennan, Inc.

Harrisburg, Pennsylvania 17120 1221 Avenue of the Americas Niw York, New York 10020 Mr. Kent Hamlin American Nuclear Insurers Mrs. Pat Higgins The Exchange - Suite 245 Edison Electric Institute 270 Farmington Avenue 1111 19th Street, N.W.

Farmington, Connecticut 06032 Wxshington, D.C.

20036 w - C_r d % s}on ]

w Mr. George Kulynych c/o Document Management Branch Babcock and Wilcox, Inc.

Washington, D.C.

20555 P.O. Box 1260 Lynchburg, Virginia 24505 LERs ONLY Mr. Bill Lavallee H

Nuclear Safety Analysis Center d

P.O. Box 10412

.0. Box 88 Palo Alto, California 94303 Middletown, Pennsylvania 17057 G. K. Hovey, Director TMI-2, Admin. Building W. F. Schmauss, TMI-2 GRC Chm., Parsippany P. R. Clark, GPUSC Parsippany A. S. Bell, TMI GORB Sec., Parsippany R. Fenti, Trailer 22 - QA M. A. Nelson, THI-l PORC Chm., Trailer 60 J. J. Barton, TMI-2 Admin. Building M. A. Shatto, TMI-1 PORC Sec., TMI-I L. W. Harding, TMI-1 Licensing, Trailer 68 G. A. Kunder, TMI-2 PORC Chm., Adm. Bldg.

N. Kszanas, Parsippany - QA D. C. Carl, TMI-2 PORC Sec., Admin. Bldg.

J. F. Wilson, TMI-2 Admin. Building B. A. Hockley, Discovery rm., Crawford St.

J. G. Herbein, Trailer 118 J. Theising, Bechtel, green building B. Ballard, Trailer 16 R. L. Rider, Bechtel, TMI-2 Admin. Bldg.

G. P. Miller, TMI-1 P. S. Walsh, GPU Parsippany R. C. Arnold, TMI-2 Admin. Bldg., and D. Buchanan, TMI-2 Admin. Buil/ing Parsippany B. D. Elam, TMI-2 Admin. Building D. G. Mitchell, Trailer 68 J. J. Chwastyk, TMI-2 Admin. Building S. D. Chaplin, TMI-2 Admin. Building G. J. Troffer, Trailer 198 R. A. Knief, Trailer 118 G. Mencinsky, Parsippany J. C. DeVine, TMI-2 Admin. Building J. Brasher, TMI-2 Admin. Building R. W. Heward, Parsippany W. N. Moreau, Parsippany J. T. Collins, NRC Trailer 1 E. G. Wallace, Licensing, Parsippany R. F. Wilson, Parsippany L. Smith, Parsippany - DDCC FILE (7) 54 J