05000456/LER-1989-017-05, :on 891206,gas Detector Channel of Process Radiation Monitor Experienced Spike,Resulting in Alert Alarm.On 891210,spike on Channel Resulted in High Radiation Alarm.Caused by Failed Detector

:on 891206,gas Detector Channel of Process Radiation Monitor Experienced Spike,Resulting in Alert Alarm.On 891210,spike on Channel Resulted in High Radiation Alarm.Caused by Failed Detector

ML20005F961
Person / Time
Site:	Braidwood
Issue date:	01/08/1990
From:	Auer M, Querio R COMMONWEALTH EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
BW-90-0029, BW-90-29, LER-89-017-05, LER-89-17-5, NUDOCS 9001170437
Download: ML20005F961 (5)

LER-1989-017, on 891206,gas Detector Channel of Process Radiation Monitor Experienced Spike,Resulting in Alert Alarm.On 891210,spike on Channel Resulted in High Radiation Alarm.Caused by Failed Detector

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(1) 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(viii)(B)
4561989017R05 - NRC Website

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January 9,1990 3

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Dear Sir:

' The enclosed Licensee Event Report from Braidwood Generating

' Station is being transmitted to you in accordance with the requirements of

,10CFR50.73(a)(2)(iv) which requires a 30-day :;ritten report. -

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This report is number 89-017-00; Docket No. 50-456.

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Enclosure:

Licensee Event Report No. 89-017-00 l

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NRC Region III Administrator

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LICENSEE EVENT REPORT (LER)

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Form Rev 2.0 facility Name (1) e Docket Number (2)

Pane (3)

Braidwand 1 01 51 01 01 01 41 51 6 1lof!0l4 Title (4)

Control Room Ventilation Actuations Due to Failed Radiation Detector Event bate (5)

LER Number (6)

Reoort Date (7)'

Other Facilities Involved (8)

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Ho?.th Day Year Year

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pg TH15 REPORT IS SUSHITTED PURSUANT TO THE REQUIREMENTS OF 10CFR

((Agek one or more of the followino) (11) 3 20.402(b) 20.405(c)

_X. 50.73(a)(2)(iv) 73.71(b)

POWER' 20.405(a)(1)(1),

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50.73(a)(2)(v) 73.71(c) 20.405(a)(1)(ii) 50.36(c)(2) 50.73(a)(2)(vil)

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LICENSEE CONTACT FOR THIS LER (12)

Name TELEPHONE NU>eER AREA CODE Mike Auer. Technical Staff Enaineer Ext.

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COMPLETE ONE LINE FOR EACH COMPON FAILURE DESCRIBED IN THIS REPORT (13) l-

CAUSE

SYSTEM COMPONENT MANUFAC-REPORTABLE

CAUSE

SYSTEM COMPONENT MANUFAC-REPORTABLE TURER TO NPRDS TURER TO NPRDS x

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SUPPLEMENTAL REPORT EXPECTED (14)

Expected Month 1 Day l Year l

Submission lyes (If vos. comg M e EXPECTED SUBMISi}0N DATE)

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ABSTRACT (Limit to 1400 spaces, i.e approximately fif teen single-space typewritten lines) (16) l On December 6,1989 the Gas Detector channel of Process Radiation Monitor (PR) OPR31J, Control Room Outside Air L'. In't;ke A, experienced a spike that resulted in an Alert Alarm on the monitor.

During the next several days L

sev:ral alert alarms were received. On December 10, 1989 a spike on the channel resulted in a iligh Radiation l

A1:rm which caused a Control Room Ventilation (VC) actuation for the OA Train of VC. After maintenance

tr ub1: shooting it was believed the spikes were due to a faulty high voltage connector which was replaced. At 0649 on December 21, 1989, a spike on the channel again resulted in the High Radiation Alarm which caused a VC tetuation for the OA VC train. At 1840 a spike on the channel resulted in another VC actuation for the OA Train of VC. During maintenance troubleshooting, it was discovered that the detector had failed. A new detector was installed and calibrated. Discrepancies with Radiation Monitoring components are being trended. This event has bien-added to that trend. Previous corrective actions are not applicable to this event.

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_ Energy Indur.try Identification System (EIIS) codes are identified in the text as (XX).

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, A,i PLANT CONDITIONS.PR10R TO EVENT:

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Event Date: December 10, 1989; Event Time: 0718; y

. Mode:, 3 - Hot Standby; Rx Power: 0%;

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'RCS [AB). Temperature / Pressure: NOT/NOP; Unit: Braldwood 1;-

Event Date:= December 21, 1989; Event' Time: 0649:

Node:' 1. Power Operation;

.Rx Power: 50%;

RCS Temperature / Pressure: NOT/NOP; Unit: -Braidwood I; Event Date: December 21, 1989; Event Time: 1840; Mode:' l'- Power Operation;'

Rx Power: 49%:-

RCS Temperature / Pressure: NOT/NOP r

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DESCRIPTION OF EVENT

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' Th:re.were no systems or components inoperable at the beginning of the event which contributed to the severity of th) event.

' On December 6,1989 the Gas Detector channel of Process Radiation Monitor (PR)tIL)' 0PR31J. Control Room Outside l Air Intake A,' experienced a spike that resulted in an Alert Alarm on the monitor. The Nuclear Station Operator

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(NS0) (Licensed Reactor Operator) confirmed that a High Radiation condition did not exist by trending the OPR313 cnd the redundant monitor, OPR32J. A Nuclear Work Request (NWR) was written to address the problem. During the n;xt several days, inspections and filter changes did not identify the cause of the problem. Several alert alarms were received during this period.

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At'0718 on December 10, 1989 a spike on the Gas Detector channel of OPR31J resulted in a High Radiation Alarm l

53tpoint being exceeded. This caused a Control Room Ventilation actuation for the OA Train of Control Room IV:ntilation (VC)[VI). As a result the following occurred:

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The OA'VC supply Fan Dampers repositioned to provide flow through charcoal adsorbers.

2.

The OA VC Hakeup Fan started.

3.

Dampers repositioned to provide flow through the OA Hakeup Filter Unit.

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traldmaad 1 0 l S l 0 l 0 l 0 1 41 51 6 8I" 0l1I7 01 0 01-3 0F 01 4 TEXTL Energy Industry Identificetion System (EIIS) codes are identified in the text as (XX)

.IN.DESCRIPTIONOFEVENT:-(Con't)-

The NSO verified all automatic actions and confirmed that e High Radiation condition did not exist..The moMtor was declared inoperable and the appropriate Technical Specification Action Statement was entered and complied with.

.J The appropriate NRC notification via the ENS phone system was made at 0858 pursuant to 10CFR50.72(b)(2)(li).

At 2027.on December 16. 1989 the maintenance troubleshooting of OPR31J was complete. The spiking was

, believed to have occurred due to a faulty high voltage connector. It was believed that the connector was generating occasional electrical noise which created false radiation signals on the Gas detector. The

connector had been replaced..The Nonitor was declared operable and the Technical Specification Action St:tement was exited.

At'0649 on December 21,'1989 a spike on the OPR31J Gas detector resulted in the High Radiation Alarm setpol'nt being exceeded. This caused the OA VC Supply ran suction Dampers to reposition. The OA VC train was in st ndby. mode. No other components receive actuation signals on a standby VC Train. The NSO verified that a High Radiation Condition did not exist. Due to a smaller spike that occurred on the redundant monitor, OPR32J. it was r:oncluded that the spikes were caused by a radio transmission in the area of the monitors.

Th} appropriate NRC notification via the ENS phone system was made at 0837 pursuant to 10CFR50.72(b)(2)(ii).

At 1840 a 'sp'ike on' the Gas Detector channel of OPR31J resulted in a High Radiation Alarm Setpoint being cxceeded.- This caused another Control Room Ventilation actuation for the OA Train of VC. The monitor was d:clared inoperable and the appropriate Technical Specification Action Statement was entered and complied

- with. A new NWR was written to investigate the cause of the spiking.

Th3 appropriate NRC notification via the ENS phone system was made at 1938 pursuant to 10CFR50.72(b)(2)(li).

At 2040 on December 30, 1989 the maintenance troubleshooting of OPR031J was completed. It was discovered th:t the detector-for the Gas Channel of monitor OPR31J had failed. A new detector was installed and

- calibrated. The Nonitor was declared operable and the Technical Specification Action Statement was exited.

This event is being reported pursuant to 10CFR50.73(a)(2)(iv) - any event or condition that resulted in (manual or automatic actuation of any Engineered Safety Feature, including the Reactor Protection System.

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Energy Industry Identification System (EIIS) codes are identified in the text as (XXT i

' -CCCAUSE'0FEVENT:

The root cause of'this event was the failure of the detector for the Gas Channel of OPR31J.'

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.1-K D(iSAFETY ANALYSIS:L o

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'This event had no effect on the safety of the plant or the public. ;There was no radioactivity present.

(OPR31J operated as designed and generated a Control Room Ventilation Actuation signal for the OA train of

. VC. The OPR32J was operable and available for redundant indication of. the activity level.

.Under more limiting conditions of actual-radioactivity, the Control Room' Ventilation would have shif ted to

the ESF safe configuration as was the case in this event.

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CORRECTIVE ACTIONS

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' All= automatic actions were verified for all three incidents.

NS0s~ verified 'that a High Radiation condition did not exist using the redundant monitor and trends on the f0PR31J.-'

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[Thidetector for the Gas Channel of monitor OPR31J was replaced.

• Discrepancies with Radiation Monitoring. components are currently being trended in the Braidwood Station Trend

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R; port program. This event has been added to that trend.

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PREVIOUS OCCURRENCES

i Th:re have been previous occurrences of spurious Control Room Ventilation Actuation Signals. In each case L

c:rrective actions'were implemented addressing both root and contributing causes. Previous corrective actions are not applicable-to this event.

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G. ' COMPONENT FAILURE DATA:

Manufacturer-Nomenclature NFG Part Number l.

- Strento Electronics Gas Detector 0360-2090-02 2%9m(010890)/6