ML20005E151

LER 89-025-00:on 891128,primary Containment Isolation Sys Group III & Standby Gas Treatment Sys Initiation Occurred. Caused by Failure of Reactor Bldg Ventilation Radiation Monitor/Sensor Converter.Converter replaced.W/891226 Ltr

ML20005E151
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	12/26/1989
From:	Pelletier J VERMONT YANKEE NUCLEAR POWER CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-89-025, LER-89-25, VYV-89-268, NUDOCS 9001030410
Download: ML20005E151 (4)

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TERMONT YANKEE NUCLEAR POWER CORPOR ATION r

GOVERNOR I!UNT ROAD F ,

VERNON, VERMONT 05354 1

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December 26, 1989 E VYV 89-268

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f* 'U.S. Nuclear Regulatory Commission 8 Document Control Desk

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Washington, D.C. 20555

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REFERENCE:

Operating License DPR-28 g . Docket No. 50-271 l l Reportable Occurrence No. LER 89-25 0 '

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Dear Sirs:

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As: defined by 10CFR50.73, we are reportin'g the attached Reportable-

.0ccurrence as LER 89-25.

p Very truly yours, VERMONT' YANKEE NUCLEAR POWER, CORPORATION

. D 0G A D WYW James P.'Pelletien Plant Manager ccs- Regional' Administrator USNRC Region I

. ,475 Allendale Road

.. King of Prussia, PA 19406 .

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NRC Eorm 384 U.S._VUCLEAR REGULATORY COMMISSION

.(9-83) APPROVED OMS NO.3150-0104

_, LICENSEE EVENT REPORT (LER) EXPIRES 8/31/95 FACILITY NAME (5) PAGE (*)

VERMONT YANKEE NUCLEAR POWER STATION DOCKET NO. (*)l 2'l0 7l1 l10F Ol5l0lol0 1 10 l3

[ TITLE.(*) INADVERTENT PRIMARY CONTAINMENT ISOLATION SYSTEM ACTUATION DUE TO A FAILURE OF L A REACTOR BUILDING VENTILATION RADIATION MONITOR SENSOR / CONVERTER EVENT DATE (*)- LER NUMBER (*) REPORT DATE (') OTHER FACILITIES INVOLVED (*)

MONTH DAY YEAR YEAR SEQ. # REV# _ MONTH DAY , YEAR FACILITY NAMES DOCKET NO.(S) 0 5 0 0 0 1l$ 2l8 8l9 8l9 -

0l2l5 -

0l0 1l2 2l6 8l9 ~~~\_ 0 5 0 0 0 OPERATING- THIS REPORT IS SUBMITTED PURSUANT TO RE0'MTS 2 '.0CFR 6: V ONE OR MORE (SS)

MODE (') N 20.402(b) __ 20.405(c) ,X 50.73(a)(2)(iv) __ 73.71(b)

E POWER __ 20.405(a)(1)(I) __ 50.36(c)(1) __ 50.73(a)(2)(v)_ __ 73.71(c)

LEVEL (50) Il d 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)

............... 20.405(a)(1)(v) 50.73(a)(2)(III) 50.73(a)(2)(x)

LICENSEE CONTACT FOR THIS LER ('8)

NAME TELEPHONE NO.

AREA CODE JAMES P. PELLETIER, PLANT MANAGER Bl d 2 21 d 71-l717lIl1 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE __ DESCRIBED IN TH[S REPORT (5 8)

CAUSE SYST COMPNT ' MFR REPORTABLE ..... CAUSE SYST COMPNT MFR REPORTABLE ......

TO NPRDS ..... TO NPRDS ......

X IlL lddT ddd0 NO . N/A ------------------------------

..... l l l ......

N/A -------------------------------- ..... N/A ------------------------------

SUPPLEMENTAL REPORT EXPECTED (58) EXPECTED MO DA YR SUBMISSION

~~l YES (If ves, complete EXPECTED SUBMISSION DATE) l NO DATE (is) l l' l ABSTRACT (Limit to 1400 spaces, i.e., approx. fifteen single-space typewritten lines) (55)

At approximately 0719 hours0.00832 days <br />0.2 hours <br />0.00119 weeks <br />2.735795e-4 months <br /> on 11/28/89, with the Reactor operating at approximately 100% power, a Primary Containment Isolation System Group III and subsequent Standby Gas Trcatment System (SBOTS) initiation occurred. The PCIS isolation, which isolates the pri-tary and secondary containment ventilation, initiated when the Reactor Building Ventilation Radiation Monitor "B" (EIIS= MON) failed upscale.

After verification of normal area radiation levels, Control Room Personnel reset the isolation and returned all systems to normal operation. Technical specification 3.2.C LCO operability requirements were satisfied at all times.

I The I&C Department investigated the problem and replaced the sensor / converter (EIIS=DET) and the monitor was declared operable at 1120 hours0.013 days <br />0.311 hours <br />0.00185 weeks <br />4.2616e-4 months <br /> on 11/29/89.

The root cause of the event is evaluated to be the lack of an'tppropriate shelf / service life specification on the sensor / converter.

NRC Form 384 (9-83)

'NRC Form 384A U.S. NUCLEAR REGULATORY COMMISSION (9-83) APPROVJ D OMS NO.3150-0104 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION EXPIE S 8-31-96 UTILITY NAME (') DOCKET NO. (e) LER NUMBER (*) PAGE (s)

_ YEAR SEO. # REV#

VERMONT YANKEE NUCLEAR POWER STATION d d d d d 217] 1 8l9 - 0l2l6 -

0l0 d? 0F d3 TEXT (If more space is required, use additional NRC Form 384A) (1')

i DESCRIPTION OF EVENT At approximately 0719 hours0.00832 days <br />0.2 hours <br />0.00119 weeks <br />2.735795e-4 months <br /> on 11/28/89, with the Reactor operating at approximately 100% power, a Primary Containment Isolation System (PCIS) Group III and subsequent Standby G 3 Treatment System (SBGTS) initiation occurred. The PCIS isolation, which isolates the r

primary and secondary containment ventilation, initiated when the Reactor Building V;ntilation Radiation Monitor "B" failed upscale.

There are two radiation detectors monitoring the Reactor Building Ventilation exhaust duct. A signal from either detector will cause the system to trip, generate an isolation signal and start the Standby Gas Treatment System.

At approximately 0723 hours0.00837 days <br />0.201 hours <br />0.0012 weeks <br />2.751015e-4 months <br />, after verification of normal area radiation levels, C:ntrol Room Personnel reset the isolation and returned all systems to normal operation.

The "B" Reactor Building Ventilation Radiation Monitor was declared inoperable at the time of the isolation.

The I&C Department investigated the problem and replaced the sensor / converter and the monitor was declared operable 9t 1120 hours0.013 days <br />0.311 hours <br />0.00185 weeks <br />4.2616e-4 months <br /> on 11/29/89.

CAUSE OF THE EVENT The immediate cause of the upscale trip was failure of the sensor / converter.

The root cause of the event is evaluated to be the lack of an appropriate shelf / service life specification on the sensor / converter. The sensor / converter had only been in service fer approximately five months but it is suspected to be a unit that had been in the stock l cystem for many years. It has recently been identified as a result of corrective actions rcsulting from a previous similar event (reference LER 89-019) that the sensor / converter has a shelf life of 7 years. Until recently, no shelf life had been specified by the

tanufacturer.

ANALYSIS OF EVENT The event 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 primary l cnd secondary containment ventilation. A PCIS Group III isolation and SBGTS initiation are the expected result of a trip of one side of the Reactor Building Ventilation Radiation Monitoring System.

l CORRECTIVE ACTIONS

1. Once radiological conditions were determined to be normal, the isolation was reset and systems returned to normal operation.

"NRC Form 384A (9-83)

n 4W4C F;rm 384A U.S. NUCLEAR REGULATORY COMMISSION (9-83)' APPROVED OMS NO.3150-0104 LICENSEE EVENT REPORT (LER) TEXT CONTINUATION EXPIRES 8-31-96 UTILITY NAME (') DOCKET NO. (8) LER NUMBER (*) PAGE (*)

YEAR SEO. # REV#

VERMONT YANKEE NUCLEAR POWER STATION d d d d d 21 Yl 1 8l9 -

0l2l5 -

0l0 d3 0F d3 TEXT (If more space is required, use additional NRC Form 384A) (1')

CORRECTIVE ACTIONS (Continued)

2. The sensor / converter was replaced with a unit that had recently undergone complete repair /recertification by the manufacturer. In the past the sensor / converter units were repaired on site but as a result of the implementation of corrective actions resultir>g f rom a past similar occurrence (reference LER 89-019) the units associated with the Group III Isolation are now sent to the manufacturer for repair /recertification. The sensor / converter that was replaced was a GE Model No.

194X927G012.

3. As a result of a past similar occurrence (reference LER 89-019) sufficient repaired /recertified units are maintained in the stock system with appropriate shelf life assigned to ensure that any sensor / converter replacement units are appropriate to perform the intended function.

4. The sensor / converter that failed will be returned to GE/Reuter Stokes for analysis to attempt to provide more information regarding the root cause of the failure.

The information obtained will be used to confirm that the corrective actions taken as a result of the past similar event were comprehensive enough to prevent recurrence. The unit will also be repaired /recertified.

5. The I&C Department will evaluate the need to periodically replace the sensor / converter units associated with the Group III Isolation. The evaluation will be based upon the results of the failure analysis and additional information to be obtained in regards to shelf and service life.

ADDITIONAL INFORMATION Similar incidents occurred and were reported under LER 89-03 and LER 89-019.

NRC Form 384A (9-83)