05000220/LER-1985-001, :on 850123,24 & 0207,automatic Initiations of Reactor Bldg Emergency Ventilation Sys Occurred.Caused by off-normal Spiking of Ventilation Duct Radiation Monitor 11.Sensor Converter Replaced

:on 850123,24 & 0207,automatic Initiations of Reactor Bldg Emergency Ventilation Sys Occurred.Caused by off-normal Spiking of Ventilation Duct Radiation Monitor 11.Sensor Converter Replaced

ML20107K161
Person / Time
Site:	Nine Mile Point
Issue date:	02/22/1985
From:	Lempges T, Randall R NIAGARA MOHAWK POWER CORP.
To:	NRC OFFICE OF ADMINISTRATION (ADM)
References
LER-85-001, LER-85-1, NMP-10624, NUDOCS 8502280163
Download: ML20107K161 (3)

LER-1985-001, on 850123,24 & 0207,automatic Initiations of Reactor Bldg Emergency Ventilation Sys Occurred.Caused by off-normal Spiking of Ventilation Duct Radiation Monitor 11.Sensor Converter Replaced

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv), System Actuation
2201985001R00 - NRC Website

text

_

e esRC Form 308 U S. NUCLEJA AE[ULATORY COMMIS$80N

1. 83' APPROVED OMG NO 319o-0104 LICENSEE EVENT REPORT (LER)

1. ACiLITV NAa#E Hi DOCKET NUMSER (2)

PAGE 433 NINE MILE POINT UNIT 41 0l5l0l0l0l2l2lc 1 lOFl ol 7 TITLE (48 ATUOMATIC INITIATION OF REACTOR BUILDING EMERGENCY VENTILATION SYSTEM EVENT DATE 154 LER NUMBER (6)

REPORT DATE 17)

OTwtR F ACILITiES INVOLVED (8)

MONTM DAY YEAR YEAR

,8, MONTn DAY YEAR P ACluTv hawES DOCKET NuwSERiSI O 151010101 1 I 0l1 d3 8 5

8l 5 0l 0 l1 0l0 0l2 2 l2 8l5 0 1 5[0l0,0g l l Twis REPORT is suSMiTTED PURSUANT TO TwE REOuiREMe=Ts 0, to Cem g iCane ea..m

.< ra, ren

,s nu

"*D'

N 20 aoacw to sost.1 X

so 73aH2H.i 73.73 6w zososwHiHe so.3stenu so r3 eH2 Hot 73.7ii :

noi 11010 to aosioniHin so.3ei.H2 gw,E song; gag sonaH2Hai 2o aoSteH1Hdd so.73teH2Hd to.73 eH2HeniH A)

Js6AJ to easteH1Hhl So.73teH2Hei Go.73(eH2HveeHE) 2o.4o8(eH11tvi to F34H2Him)

So 731eH2Hal LICENSEE CONTACT FOR TulS LER (121 NIME TELEPMONE NOUSER ARE A CODE ROBERT RANDALL, SUPERVISOR TECHNICAL SUPPORT 311 15 31419 I-l21 414l5 COMPLETE ONE LiNE FOR EACM COMPONENT F AILURE DESCRIBED IN Tul8 REPORT t131 MA AC-REP WA AC REP E

CAUSE

Sv8TEU COMPONENT

CauSE

SYSTEM COvPONENT O PR S yO NPR X

IlL R IE I I GI 01 8 10 Y

l I i l l l 1 I

I I I I I I I

I I I I I I SUPPLEMENTAL REPORT EXPECTED H46 MONTw CAV YEAR SL8vis$ SON YES fl9 ver, ca.nps.te Ex!ECTED Svincts3 ION DATil NO l

l l

AesTRAC,et

,M uoo em.

.-..,r.n

.,.M=.

w r,..,s.

,oe, ABSTRACT During normal operation on January 23, 1985, the first of three auto initiationc of the Reactor Building Emergency Ventilation System occurred (other initiations occurred on 1/24/85 and 2/7/85). The three initiations were a result of an off-normal spiking of No. 11 Reactor Building Ventilation Duct Radiation Monitor.

In each case a work request was issued to troubleshoot the problem and recalibrate the unit after corrections were made. After initially tightening, and then rewiring the sensor converter cable connectors, the sensor converter unit was replaced and source calibrated following the third emergency ventilation initiation.

Problems with No.

11 Reactor Building Ventilation Duct Radiation Monitor have been resolved and the unit is operating properly.

8502280163 850222 ADOCK0500gO PDR S

NRCPerm 308 19 431 Lu

a e assa u s. auctama aeoutaroav co==.essoa LICENSEE EVENT REPORT (LER) TEXT CONTINUATION amovEc ows aio modio.

EXP5AES. 8/3145 Pacaufv mase ela cock 47 auasseR t23 LSA esunsetA 106 Pae8 (3 88Q8]Td'b b

S, vtam O l0 0l2 0F 0 l2 NINE MILE POINT UNIT 41 0 j5 l0 l0 l0 l21210 8l 5 0 l0 l 1 rexT,,-==.===t macr anawim

- TEXT During normal operation on three separate occasions No. 11 Reactor Building Ventilation Duct Radiation Monitor experienced a spurious spike which initiated the Emergency Ventilation System. The first two initiations occurred on January 23, and 24, 1985. Following the spike the indications returned to normal, the HI radiation signal was reset and system cleared. Work requests were issued following each initiation in order to troubleshoot and make the needed repairs. It was discovered that the automatic initiation of the Emergency Ventilation System occurred due to a malfunction of the sensor converter unit.

Following the first system initiation loose connectors were tightened on the sensor convertor cables. These connectors were later rewired after the second system initiation. The third automatic initiation occurred on February 7, 1985.- This time the Emergency Ventilation System was left in operation and a new sensor converter unit was installed. In each case No. 11 Reactor Building Ventilation Duct Monitor was source calibrated by Radiation Protection following repairs. Problems with the unit have been corrected and it is now operating properly.

ASSESSMENT OF' POTENTIAL SAFETY CONSEQUENCES Reactor Building Ventilation Duct Radiation Moni+qr No. 11 experienccd a spurious spike and initiated the Emergency Ventilation System on a reading greater than 5mR/hr. Since the system did initiate as designed and emergency vent operation is a conservative mode, the system initiation posed no threat to the safety of the plant.

A redundant reactor building ventilation monitor is provided. Therefore, had Radiation Monitor No. 11 been inoperable, redundant Reactor Building Ventilation Monitor No. 12 would have been available to initiate the Emergency Ventilation System on a reading above SmR/hr. The sensor converter for Reactor Buildina Ventilation Monitor No. 11 has been replaced and source calibrated. No furthei spiking problems with monitor No. 11 have been experienced.

Based on these results, there were no actual adverse consequences from this event and the potential consequences are within the design basis of the plant.

CORRECTIVE ACTION

The sensor converter cable connectors for Reactor Building Ventilation Duct Monitor No. 11 were initially tightened and then rewired in efforts to resolve the spiking problem. The sensor converter for ventilation Duct Monitor No. 11 was finally replaced and successfully source calibrated. Af ter Channel til was proved operational and returned to service, Channel #12 was inspected for loose connector connections and repaired accordingly.

gmau m.

{[;

~~

NMP-10624 NIAGARA MOHAWK POWER CORPORATION NIAGARA MOHAWK 300 ERIE BOULEVARD, WEST SYR ACUSE. N. Y.13 202 February 22, 1985 United States Nuclear Regulatory Commission Document Control Desk Washington,.DC 20555

^

RE:

Docket No. 50-220 LER 85-01 Gentlemen:

In accordance with 10 CFR 50.73, we hereby submit the following Licensee Event Report:

LER 85-01 Which is being submitted in accordance with-10 CFR 50.73 (a)(2)(iv).

"Any event or condition that resulted in manual or automatic activation' of any Engineered Safety Feature."

10 CFR 50.72 reports were made at 0130 on 1/23/85, 1915 on 1/24/85 and 0833 on 2/7/85. This Licensee Event Report was completed in the format designated in NUREG-1022, dated September 1983.

Very truly yours, fgv>Hbj -

W Thomas E.

Lempges Vice President Nuclear Generation TEL/lo attachments-cc Dr. Thomas E. Murley Regional Administrator

$'k t