ML20006B470

LER 89-026-00:on 891223 & 900105,primary Containment Isolation Sys Group III Isolation & Standby Gas Treatment Sys Initiations Occurred.Caused by Failure of Sensor Converter.Isolation Reset & Monitor bypassed.W/900122 Ltr

ML20006B470
Person / Time
Site:	Vermont Yankee
Issue date:	01/22/1990
From:	Pelletier J VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-026, LER-89-26, VYV-90-005, VYV-90-5, NUDOCS 9002020259
Download: ML20006B470 (5)

Text

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VERMONT YANKEE NUCLEAR POWER CORPORATION t'

P. O. BOX 157 i GOVDtNOR IIUNT ROAD '

VERNON, VERMONT 05354 January 22, 1990 ,

VYV# 90-005

(

r U.S. Nuclear Regulatory Commission l Document Control Desk '

Washington, D.C. 20555

REFERENCE:

Operating License DPR-28 i Docket No. 50-271  ?

Reportable Occurrence No. LER 89-26  :

I

Dear Sirs:

As defined by 10CFR50.73, we are reporting the attached Reportable Occurrence as LER 89-26, Very truly yours,

! I VERMONT YANKEE NUCLEAR POWER CORPORATION l ,

h M Unmes P. Pelletier Plant Manager cc Regional Administrator I USNRC Region I  ;

475 Allendale Road King of Prussia, PA 19406 l

f i

r

?

9002020259 900122 -

PDR ADOCK 05000271 S PDC ggQ ty;

r NRC F;rs.366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMS NO.3150-0104 (6-89)

EXPIRES 4/30/92

. ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST:

50.0 HRS. FORWARD' COMMENTS REGARDING LICENSEE EVENT REPORT (LER)- BURDEN ESTIMATE TO THE RECORDS AND REPORTS -

MANAGEMENT DRANCH (P-530), U.S. NUCLEAR  ;

REGULATORY COMMISSION, WASHINGTON, DC '

20555, AND TO THE PAPERWORK REDUCTION ,

PROJECT (3160-0104), OFFICE OF MANAGEMENT .!

AND DVDGET, WASHINGTON. DC 20603. ,

FACILITY NAME (') 00CKET NO. *) FAGE (*)  ;

VERMONT YANKEE NUCLEAR POWER STATION ~ 015l0l01(012l7l1 0l110Fl014  !

TITLE (*) INADVERTENT PRIMARY CONTAINMENT ISOLATION SYSTEM ACTUATIONS DUE TO. SPIKES ON A- [

REFUEL FLODR RADIATION MONITOR.- i EVENT DATE (_8). (ER NUMBER (*) REPORT DATE_(') OTHER FACILITIES _ INVOLVED (*)

MONTH DAY EAR YEAR SEO. # REV# MONTH DAY YEAR FACILITY NAMES- DOCKET NO.(S) -

0 5 0 0 0 i M2 213 8.19 819 -

01216 -

Ol0 0l1 2 l2 9 l0 0 5 0 0 0 ,

OPERATING THIS REPORT !$ SUBMITTED PURSUANT TO RE0'MTS_OF IOCFR J: ( ONE OR MORE ( 1) l MODE (*) N 20.402(b) _ 20.405(c) X 50.73(a)(2)(iv) _ 73.71(b) 3 POWER _ 20.405(a)(1)(1) _ 50.36(c)(1) _ 50.73(a)(2)(v) _ _ 73.71(c) j LEVEL (") 110!0 20.405(a)(1)(II) _ 50.36(c)(2) _ 50.73(a)(2)(vii) _

OTHER:  ;

............... _ 20.405(a)(1)(III) _ 50.73(a)(2)(I) _ _ 50.73(a)(2)(viii)(A)  :

............... _ 20.405(a)(1)(iv) _ 50.73(a)(2)(II)~ _ 50.73(a)(2)(viii)(B) {

...m ......... 20.405(a)(1)(v) 50.73(a)(2)(!!!) 50.73(a)(2)(x) '

LICENSEE CONTACT FOR THIS LER (5: 3 ,

NAME TELEPHONE NO.

AREA -l CODE . - --

JAMES P. PEGSTIER. PLANT MANAGER 8I Ol 2 2l517l-l7l7lIl1

• J $ ETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT ( " )

CAUSE PT f NMPNT HFR REPORTABLE ..... CAUSE SYST COMPNT MFR REPORTABLE ...... ,

_,4 TO NPRDS ..... TO NPRDS ......

. . . . . '{

3 .....  :

i l1I III ..... l- llI llI I I I l- 1Il Z l ll l l l l l- I '.

SUPPLEMENTAL REPORT EXPECTED (") EXPECTED _MO DA YR ,

SUBMISSION -

M YES (If ves, complete EXPECTED SUBMISSION DATE) ] NO DATE (18) 01 4 Ol1 91 0 I

ABSTRACT (Limit to 1400 spaces, i.e., approx.: fif teen single-space typewritten lines) ('*)

At approximately 1830 hours0.0212 days <br />0.508 hours <br />0.00303 weeks <br />6.96315e-4 months <br /> on' 12/23/89, and 2003 hours0.0232 days <br />0.556 hours <br />0.00331 weeks <br />7.621415e-4 months <br /> on 01/05/90, both.with the .;

rGactor operating at approximately 100% power, Primary Containment Isolation System Group  ;

III isolation and subsequent Standby Gas Treatment System (SBGTS) initiations occurred. l Tha PCIS isolations, which isolate the primary and secondary containment _ ventilation,  !

initiated when the Refuel Floor Radiation Monitor "A" (EIIS= MON) spiked upscale.

After verification of normal area radiation levels, Control Room personnel reset. f th2 isolations and returned all systems to normal operation.

The cause of the spiking is suspected to be age related failure of the sensor /

c nverter. However,.due to an apparent relationship between the spiking and control room-01r.ctronics that apparently existed in the first event, additional actions were considered nect;ssary. The monitor remains bypassed and additional troubleshooting to confirm--the

- coun is ongoing. The upscale trip of the radiation monitor can remain bypassed and still satisfy Technical Specification operability requirements. The other radiation monitors atrociated with the Group III isolation are operating'normally.

Additional corrective actions will be specified as determined ' appropriate when the -~

c u n is identified. ,

.NRC F';rm 366,(6-89); ,

x _ _ _

a NRC Form 366A U.S,' NUCLEAR REGULATORY COMMISSION APPROVED OMS NO,3150-0104 (6+D9)~ -

EXPIRES'4/30/92

. ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST:

50.0 HRS. FORWARD COMMENTS REGARDING LICENSEE EVENT REPORT (LER) DURDEN ESTIMATE TO THE RECORDS AND REPORTS TEXT CONTINUATION MANAGEMENT BRANCH (P-530), U.S. NUCLEAR REGULATORY _ COMMISSION, WASHINGTON, DC

' 20550, AND TO THE PAPERWORK REDUCTION PROJECT (3160-0104), OFFICE OF MANAGEMENT AND DVDGET, WASHINGTON. DC 20603.

UTILITY NAME (') DOCKET NO, (*) LER-NUMBER (*) PAGE (*)

YEAR SEO. # REV8 ,

VERMONT YANKEE NUCLEAR POWER STATION d d d d d 2l711 8l9 -

0l2l6 -

0l0 d2 0F 014 TEXT (If more space is required, use additional NRC Form 366A) ( ')

DESCRIPTION OF EVENT JVENT #1 At approximately 1830 hours0.0212 days <br />0.508 hours <br />0.00303 weeks <br />6.96315e-4 months <br /> on 12/23/89, with the reactor operating at.approximately l 100% power, a Primary Containment Isolation System (PCIS) Group III and' subsequent Standby Gas Treatment System (SBGTS) initiation occurred. The PCIS isolation, which isolates-the primary and secondary containment ventilation, initiated when the Refuel Floor Rudiation-Monitor "A" spiked upscale. Erratic indication of the meter was observed and the monitor.

wa3 bypassed and declared inoperable.

At approximately 1837 hours0.0213 days <br />0.51 hours <br />0.00304 weeks <br />6.989785e-4 months <br />, after verification of normal area; radiation levels, Control Room personnel reset the isolation and returned the ventilation systems to normal cperation.

During the following two and one half' hours, with the radiation monitor still' bypassed, eight additional trips of the monitor were observed. At this: time the Indicator and Trip Unit module was partially withdrawn from the panel mounted equipment' rack by the-Op3 rations Department. Over the next two hours, no additional trips occurred. The unit w:s then inserted back into the equipment rack and no additional trips occurred.

Based upon the erratic performance of-the Indicator and Trip Unit and the changetin th) performance as the connectors and cables on the unit-were slightly' repositioned,-the I&C Department suspected that the trip had been caused by intermittent connections.c The connec-tions were checked and no apparent problems were found.. The connections were cleaned and th3 unit was functionally tested. The unit was monitored and no additional abnormal per-forsance occurred. The monitor was declared operable and removed from bypass.on 12/28/89.

EVENT #2 At approximately 2003 hours0.0232 days <br />0.556 hours <br />0.00331 weeks <br />7.621415e-4 months <br /> on 01/05/90, with the reactor operating at approximately_

• 100% power, a Primary Containment Isolation System (PCIS) Group III and_ subsequent Standby Gas Treatment System (SBGTS) initiation occurred. The PCIS isolation, which-isolates the pritary and secondary containment ventilation, initiated when the Refuel Floor Radiation-Monitor _"A" spiked upscale.

At approximately 2016 hours0.0233 days <br />0.56 hours <br />0.00333 weeks <br />7.67088e-4 months <br />, after verification of normal area' radiation levels,

-C;ntrol Room personnel reset the isolation and returned the ventilation systems to normal

. operation.

At approximately 2100 hours0.0243 days <br />0.583 hours <br />0.00347 weeks <br />7.9905e-4 months <br />, the radiation monitor was bypassed and declared.

inoperable.

The Instrument and Control Department investigated the occurrence and found---

n3 obvious equipment problems. The monitor was left bypassed and recording equipment was ccnnerted in orderito determine where in the circuit the spiking was occurring. ~The

- rce:rding equipment is connected in a configuration that will show whether the spikingfis-originating from.the sensor / converter or the indicator and trip unit.

NRC F rm 366 (6-89)

NRC Form 366A. U.S. NUCLEAR REGULATORYt COMMISSION APPROVED OMS NO,3160-0104 (6-89)* y EXPIRES 4/30/92.-

ESTIMATED BURDEN PER RESPONSE TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST:

50.0 HRS. FORWARD COMMENTS REGARDING LICENSEE EVENT REPORT (LER) BURDEN ESTIMATE TO THE RECORDS AND REPORTS TEXT. CONTINUATION MANAGEMENT BRANCH (P-630),.U.S. NUCLEAR

. REGULATORY COMMISSION, WASHINGTON,:DC 20656, AND TO'THE PAPERWORK REDUCTION PROJECT:(2160-0104), OFFICE OF MANAGEMENT -

AND BUDGET. WASHINGTON, DC 20603.

UTILITY.NAME (5) DOCKET NO. (8) LER NUMBER (*) PAGE (8) .

YEAR SEO. # REV# $

VERMONT YANKEE NUCLEAR POWER STATION O! S! d O! O! 21711 8l9 -

0l2l6 -

0l0 Ol 3 0F 014 TEXT (If more space is required, use additional.NRC Form 366A) (")

BOTH EVENTS There are two radiation detectors monitoring the Refuel Floor. A signal from either detector will cause the system to trip, generate an isolation signal and start the Standby G;s Treatment System.

CAUSE_0F THE EVENTS Based upon past experience with similar occurrences, it-is suspected that the cause--

cf these events was age related failure of the sensor / converter. However, due_to an apparent relationship between the spiking and the control room electronics, that apparently cxisted in the first event, it was determined that rather than replace the sensor / converter it was necessary to attempt to confirm where in the circuit the spiking was occurring.

Additional efforts to confirm the cause are ongoing.

ANALYSIS OF EVENTS The events did not have adverse safety implications to plant equipment or the public.

The PCIS Group III and SBGTS operated as designed and successfully: isolated the pri-t:ry and secondary containment _ ventilation. A PCIS Oroup III isolation and SBGTS initiation ara the expected result of a trip of one side of the Refuel Floor Radiation Monitoring System.

The upscale trip of the radiation monitor can remain. bypassed and still satisfy Tcchnical Specification operability requirements. -The other radiation monitors associated

-with the Group III isolation are operating normally.

CORRECTIVE ACTIONS

1. Once radiological conditions were determined to be norral, the isolations were reset and-

. ventilation systems returned to normal operation.

2. Observation and troubleshooting immediately.following the first event identified-a=relaa tionship between the erratic performance e d the connections on the rear of the unit.

'3. The connections were checked and no apparent problems were found. The' connections were cleaned and the unit was functionally tested.

14. The monitor was bypassed and recording equipment was connected in a configuration that upon occurrence of additional spiking will show whether it is originating from the-tensor / converter or the indicator and trip unit. The monitor remains bypassed _with the recording equipment connected.to date.

6.jAdditional corrective actions will be specified as determined appropriate when the root cause.is identified.

NRC F;rm- 3 66_-'- ( 6- 8 9 ) <

r,

^

NRC F;rm 365A U.S. NUCLEAR RLGULATORY COMMISSION APPROVED DMS No.3150-0104 -l (6-89)* ,* EXPIRES 4/30/92-ESTIMATED BUROEN-PER RESPONSE ~TO COMPLY WITH THIS INFORMATION COLLECTION REQUEST:

50.0 HRS. FORWARD' COMMENTS REGARDING LICENSEE EVENT REPORT (LER) BURDEN ESTIMATELTO THE RECORDS AND REPORTS TEXT CONTINUATION MANAGEMENT BRANCH (P-E30), U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555,.AND TO THE PAPERWORK REDUCTION PROJECT (3160-0104), OFFICE OF MANAGEMENT-AND BUDGET. WASHINGTON, DC 20603.

UTILITY NAME ($) DOCKET NO. (*) LER NUMBER (*) PAGE'(*)-

YEAR SEO. 8 REV8

,_ VERMONT YANKEE _ NUCLEAR POWER STATION d d d d d 2l711 8l9 -

0l2l6 -

0l0 Ol'4 0F d4 TEXT (If more space is required, use additional NRC Form 366A) ($')

ADDITIONAL INFORMATION Other incidents involving spiking or failure of Radiation Monitors resulting in Grcup III isolations have occurred and were reported under LER's 85-11, 89-03,.89-19, and 89-25.

n.

NRC Form 366.(6-89) -