ML20005E272

LER 89-032-00:on 891203,both Channels of Source Range Hi Flux at Shutdown Alarm Found Blocked.Caused by Personnel Error.Channel Unblocked,Dilution Accident Verified Not in Progress & Operator Involved counseled.W/891229 Ltr

ML20005E272
Person / Time
Site:	Millstone
Issue date:	12/29/1989
From:	Langan J, Scace S NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-032, LER-89-32, MP-13904, NUDOCS 9001040191
Download: ML20005E272 (4)

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@Northea'stEnergy NucioafE**aNEtIEE'vUE'o'ma*"y P.O. Box 270 HARTFORD. CONNECTICUT 06414-0270 Company e

(203)665-5000 Re: 10CFR50.73(a)(2)(i)

December 29, 1989 MP-13904  !

U.S. Nuclear Regulatory Commission Document Control Desk

' Washington, D.C. 20555

Reference:

Facility Operatine License No. NPF-49 Docket No. 50-433 Licensee Event Report 89-032 1 Gentlemen: i This letter forwards Licensee Event Report 89-032-00 required to be submitted within i thirty (30) days pursuant to 10CFR50.73(a)(2)(i), any operation or condition prohibited by the plant's Technical Specifications.

Very truly yours.  ;

f NORTHEAST NUCLEAR ENERGY COMPANY FOR: Stephen E. Scace 1 Station Superintendent  !

Millstone Nuclear Pov er Station BY: arl . ement

' Unit 3 Superintendent Millstone Nuclear Power Station SES/JAL:tp

Attachment:

LER 89-032-00

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cc: W. T. Russell, Region 1 Administrator W. J. Raymond, Senior Resident inspector, Millstone Unit Nos.1, 2 and 3 D. H. Jaffe, NRC Project Manager, Millstone Unit No. 3 9001040191 891229 $gn PDR ADOCK 05000423 I s PDC s i

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NHC Fqrm 366 - U.S. NUCLE AR REGA ATORY COMM!SS'ON APPRQvtD OMB NO. 3t60-0104 '

(6-89) EXPIRE S: 4/30 92 Eshmated burdsn per responsa to comply voth this information colisction tsouest: 60 0 hrs. Forward i Comments FPQarding buroen estimate to tne Re0oros i LICENSEE EVENT REPORT (LER)- and Reoorts Management Branch (p-630). U S. Nuclear i Regulatory Comm.ssion. Wasnington. DC 20555 and to tne Paperwork Reduction Project (3150-0104L Office of Management and Buopet. Wasnington. DC 20503 F ACILIT Y NAME .0 ) .

DOWE I NJMbEh gj W l Millstone Nuclear Power Station Unit 3 ol5!ofofoldl2l3 1lOFl 0l 3 llTLE oli Two Channels of Hi Flux at Shutdown Inoperable Due to Personnel Error EVENT DATE 15) LEn NJMBER f 6) REPORT DATE 17) OTHER F ACluTIES INVOLVED '8)

MONTH DAY YEAR YEAR MONTH DAY YEAR F ACUTY NAME6 01siololof I I 1

,j 1 2 0l3 8 9 8 l9 0l3l2 0l 0 1l 2 2l 9 8l9 n; 3; og n; o 9 ;

OPERATlNO T*tS RE* ORT IS BEING SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CSR l. ICneck one or more of tne followinguit) l MODE @ 20 402(c) 20.402(c) - 50.73(aH2Hiv) 73. h ib) 1 pow g 20.405(aH1)(1) 50 36(c)O) 60.73ta H2 Hv) 73.71(c) i hik 0l0l0

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60. 73(a H2H viii)( A) Text. NRC Form 366A) 20 405(a)O Hiv) 50.73(aH2Hii) 50,73(a)(2HviinHB) 20 406 f aif1)fiv) 60. 73 t a H2 HiiO 50. 73 f a H2 s ix)

UCENSEE CONT ACT FOR THS LEA f12)

NAMg TELEPHONE NUMBER Jeffry A. Langan, Ext. 5544 '"

• 2l0l3 4l4l7l-l1l7]9l1 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DES 5 BED IN THIS REPORT f13i CAUSE SYSTEM COMPONENT hMO* CAUSE SYSTE COMPONENT pgC. g '

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I III I I I I III -l i I SUDPLEVENTAL REPORT EXDECTEC f14) MONTH DAY YEAR SUDM'SSION

] YES Of yes. comoiete EXPECTE0 SUBMISSION DATE) NO DATE 061 g g g ABSTRACT (Limit to 1400 spaces. Lo.. approximately fifteen sing +e-soace typewritten anos) (16)

On December 3,1989, at 0320 hours0.0037 days <br />0.0889 hours <br />5.291005e-4 weeks <br />1.2176e-4 months <br />, with the plant in hiode.5,132 degrees Fahrenheit and 65 psia, both channels of Source Range Hi Flux at Shutdown alarm were found blocked. Operations personnel immediately unblocked both channels ~and verified a dilution accident was not in progress as required by plant Technical Specifications. '

. The root cause of this event was personnel error. To prevent this from recurring, the Modes 1 - 4 and Modes 5-6 control room log sheets have been revised to include-verification that the Hi Flux at Shutdown is unblocked if source range counts are below the alarm setpoint. In addition, this LER was routed to all licensed operators, and will be included in the operator requalification program. The operator involved in incorrectly signing off the step has been counseled.

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NRc Form 360A U.S. NUCLE AR REGULATORY CoMMISSON APPROVED OMB No. 3160-C1o4 iV .4-691 E XPIRE S: 4 /30 /92 Estim.ted tsare.n per r.spons. to compty witn this -

LtCENSEE EVENT REPORT (LER) 'njormg,y,ct,*ngg5 Mfg,0,,h',*g,5747,0,,, .

L TEXT CONTJNUATION .no R.oons u.n.g.m.ni er.nen ip.sson u.s. Nuci..r Re.Quinto.ry in P r*oncommession. Was.tiin9 R.oucuan pro, ton. De 20sss ci <aisc-oio4 and of n ovne. to M.n ao.m.nt o ano suop.t w.sninoton. oc rosos.

. F AclLrrY NAME ( t) .

DOCKET NVMBER (2) LEn NuuMn to PAGE 13) vEAR @

Niillstone Nuclear Power Station Unit 3 ol6[ol0lol4l2l3 8l9 0l3l2 0l0 0l 2 OF 0l3 TEXT ot more so c. is r aun.o. us. .aomon.i NRc Form a66A s) (17)

1. Descrintion of Event On December 3,1989, at 0320 hours0.0037 days <br />0.0889 hours <br />5.291005e-4 weeks <br />1.2176e-4 months <br />, with the plant in Mode 5 (Cold Shutdown),132 degrees Fahrenheit and 65 psia, both channels of Source Range Hi Flux at Shutdown (HFSD) alarm were ,

found blocked. The condition of the HFSD alarm was discovered by the Supervismg Control Operator (SCO) during a review of the hiain Control Board 4 annunciator panel. Operators immediately unblocked both channels of Source Range Hi Flux at Shutdown, and verified a dilution accident Tvas not in progress as required by plant Technical Specifications.

II. came nf Frent ,

The root cause of this event was personnel error. Operator procedure OP 3207 Reactor Shutdown, directs operations to unblock the HFSD alarm when source range counts drop below the alarm setpoint as indicated by the HFSD bistable status light on the nuclear instrumentation cabinet extinguishing.

When the plant was shutdown on November 28, 1989, there was approximately a one hour and twenty five minute delay between the time when the plant entered Mode 3 (Hot Standby) and source range counts dropped below the HFSD setpoint. Normally, the procedure step should have remained open and flagged as an open item to be completed when plant conditions permit.

However, when proceeding through OP 3207, the operator inadvertently initialed the step as completed. Further, the requirement for the HFSD alarm to be unblocked when in Modes 3, 4, and 5 was not included in the control room log sheets. As a result of these inadequacies, the HFSD alarm remained blocked from approximately 2020 hours0.0234 days <br />0.561 hours <br />0.00334 weeks <br />7.6861e-4 months <br /> on November 28,1989, until 0320 on December 3,1989.

III. An** of Event This event is reportable under 10CFR50.73(a)(2)(i), as an operation proltibited by the plant's Technical Specifications. In blodes 3, 4, and 5: plant Technical Specif; cations require one channel of source range instrurnentation be operable ( or two channels if the reactor trip breakers are closed). The function of the source range instrumentation is to monitor the reactivity of the core, alert operators in the event of an unexpected addition of positive reactivity to the core, and provice a reactor trip signal if a preset count level is reached. Had a dilution accident occurred while the HFSD alarm was blocked, operators ma3 not have detected it until the Source Range Hi Flux reactor tnp setpoint was reached. (Even with the reactor trip breakers open, the first out annunciator on the reactor trip annunciator panel would sound). This scenario is extremely unlikely, however, since operators have indication of source range counts at both Main Control Board 4 and the Nuclear Instrumentation panel. Source range counts are also recorded on a strip chart recorder on Main Control Board 4, and an audible count rate signal is mamtained in the Control Room. With all these indicators available to the operators, coupled with the very slow rate at which a dilution accident would progress, it is reasonable to expect that an inadvertent dilution would be detected and corrected before shutdown margin requirements were violated. Therefore, this event had no significant impact on plant safety.

l NRc Form a66A (6-891

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NRC FoPm 366A U.S. NUCLE AR REOULATORY COMM:SSION APPROVED OMB NO 3160-0104 (6-69)i EX* IRES. 4 /30/92 Estimatec baroen per response to comply with tnis

'ntormaten conect on reauest so o nrs. Forwere y* LICENSEE EVENT REPORT (LER) -

Comments regarding buroen estimate to the Aetores TEXT CONTINUATION ano neports uanagement eranen ip.63oi. u.s. Nucioar Aegulatory Commission. Washington. DC 20E55 and to the Paperwork Aeouction proiset Q16W0104). Office of Management and Bucoet. Washinoten DC 20603 F ACILITY NAME (t) . DOCKET NUMBER (2) t Fn Inivppn set PAGE Q1 YEAR -WN N Millstone Nuclear Power Station U"il 3 0l 6l 0l 0l 0l4 l2 l3 8l9 0l 3l 2 0] O 0l 3 Or 0l3 TEXT (11 rnore space is recuaroc. use accetional NRC Form 366A o) 07)

IV. Corrective Action Both channeh of Source Range Hi Flux at Shutdown were immediately unblocked, and the operators 'zerified a dilution accident was not in progress as required by plant Technical Specifications. In addition, the plant process computer was queried to verify that the HFSD had been blocked since the shutdown on November 26.1989. To preclude this event from recurring, a change has been made to the Mode 1 - 4 anc Mode 5 - 6 control room log sheets to ensure the HFSD alarm is unblocked in Mode 3 and below, when source range counts are below the setpoint, in addition, this LER was routed to all licensed operatorsi and will be included in the operator requalification program. The operator involved in incorrectly signing off the step has been counseled.

V. Addi'innnl Information There have been no other LER's with the same root cause and sequence of events.

Ells Code <

Svetems Comnonents IG - Incore/Excore Monitoring System JA - Alarm, Power l

NRC Form 366A (6-89)

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