ML18096A399

LER 91-032-00:on 911114,containment purge/pressure-vacuum Relief Sys Isolation Signal Actuated.Caused by High Channel Spike on Containment Particulate Radiation Monitor 1R11A. Channel Calibr Check Performed satisfactorily.W/911212 Ltr

ML18096A399
Person / Time
Site:	Salem
Issue date:	12/12/1991
From:	Leap B, Vondra C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-91-032, LER-91-32, NUDOCS 9112260010
Download: ML18096A399 (5)

Text

.. Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station December 12, 1991 U. S. Nuclear Regulatory Commission Document Control Desk Washington, DC 2d~55

Dear Sir:

SALEM GENERATING STATION LICENSE NO. DPR-70 DOCKET NO. 50-272 UNIT NO. 1 LICENSEE EVENT REPORT 91-032-00 This Li~ensee Event Report is being submitted pursuant to the requirements of the Code of Federal Regulations 10CFR 50.73(a) (2) (iv). This report is required to be issued within thirty {30) days of event discovery.

Sincerely yours,

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C. A Vondra General Manager -

Salem Operations MJP:pc Distribution

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91/J.}b 0010 95-2189 (10M) 12-89

I NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION e

16-891 APPFJOVED OMB NO. 3150*0104

.. EXPIRES: 4/30/92 ATED BURDEN PER RESPONSE TO COMPLY WTH THIS

• I RMATION COLLECTION REQUEST: 50.0 HRS. FORWARD LICENSEE EVENT REPORT (LERI COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS AND REPORTS MANAGEMENT BRANCH IP-5301. U.S. NUCLEAR REGULATORY COMMISSION. WASHINGTON. DC 20555. AND TO THE PAPERWORK REDUCTION PROJECT 13150-01041. OFFICE OF MANAGEMENT AND BUDGET. WASHINGTON. DC 20503. .

FACILITY NAME 11 I DOCKET NUMBER 121 PAGE 131 Salem Generating Station - Unit 1 TITLE 141

! 0 I 5 I 0 I 0 I 0 I 2, 7 I 2* I 1 0 F 0 14 ESFActivation Signal for Cont. Vent. Isolation Due To Inadequate Design EVENT DATE (51 LEA NUMBER 161 REPORT DATE 171 OTHER FACILITIES INVOLVED IBI MONTH DAY YEAR YEAR (} SEQUENTIAL NUMB EA' >>: REVISION NUMBER MONTH OAY YEAR FACILITY NAMES DOCKET NUMBERISI 0 I5 Io I o I o I I I 1 11 114 9 1 91.1 0 ~ 12 -D 10 ~ 12 1 12 9\1 0 I 5 Io Io I o I I I THIS REPORT IS SUBMITTED PURSUANT TO THE R~QUIREMENTS OF 10 CFR §: (Chock one or mqre of rhe following) 111 I OPERATING 1 1---,-----------r--.----------~---,.-----------.---,.--------~-t MODE (91 20.402(bl

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- OTHER (Specify 1n Abstr*ct bolow *nd m Texr. NRC Form 366A) 20.4051*111 llvl

- 50.73l*ll2lliiil 50.731*11211xl LICENSEE CONTACT FOR THIS LER 1121 NAME TELEPHONE NUMBER AREA CODE B. w. Leap

i Io 19 3 13 19 I 2 12 I 11 4 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (131 MANUFAC* MANUFAC*

CAUSE SYSTEM COMPa°NENT TUR ER TUR ER I I I I I I I

-:;:::.::>:::::::::::.:::,*::;1*::::**:. I, I I I I I I I I I I I I I  :::::::::*:::::::: :::::::::;;:::: \ I I I I I I I SUPPLEMENTAL REPORT EXPECTED 1141 MONTH DAY YEAR EXPECTED

~NO SUBMISSION I YES I/I vos. comp/or. EXPECTED SUBMISSION DATE)

DATE (151 I I I ABSTRACT (Limit to 1400 _spaces, i.a .. afJf)rD:KimartJly fifteen singlt1*sp.ac~ rypewrirran Imes} (16)

On 11/14/91, a Maintenance Instrument and Controls (I&C) technician began a preventive* maintenance (PM) task to open, clean, inspect and close the sample box for the Radiation Monitoring System (RMS)

Containment Particulate Radiation Monitor, lRllA. At 0842 hours0.00975 days <br />0.234 hours <br />0.00139 weeks <br />3.20381e-4 months <br /> the same day, during the performance of the PM task, a Containment Purge/Pressure-Vacuum Relief System (CP/P-VR} isolation signal actuated as a result of a high channel spike on lRllA. The associated containment isolation valves were closed at the time and did not change position as a result *of the isolation signal. The C_P /P-VR System isolation is an Engineered Safety Feature (ESF) . The root cause of the channel spike is attributed to a design inadequacy. As indicated by prior LERs, the RMS channels are subject tci intermittent spikes due to external influences. Investigation could not identify the specific cause of this channel spike. The lRllA channel was restored following the investigation. A channel calibration check was completed satisfactorily. Subsequently, the Action Statement was exited November 14, 1991, at 1105 hours0.0128 days <br />0.307 hours <br />0.00183 weeks <br />4.204525e-4 months <br />. The event was discussed with the appropriate Maintenance I&C RMS qualified technicians. The Maintenance Department Work Standard "Paperchange has been revised to provide instructions for blocking the channel trip function. The desiqn of the entire RMS system is being reviewed and the appropriate design changes will be implemented to enhance the system.

NRC Form 366 16-891

LICENSEE EVENT REPORT {LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 91-032-00 2 of 4 PLANT AND SYSTEM IDENTIFICATION:

Westinghouse - Pressurized Water Reactor Energy Industry Identification System {EIIS) codes are identified in the text as {xx}

IDENTIFICATION OF OCCURRENCE:

Event Date: 11/14/91.

Report Date: 12/12/91 This report was initiated by Incident Report No.91-831.

CONDITIONS PRIOR TO OCCURRENCE:

Mode 1 Reactor Power 100% - Unit Load 1152 MWe DESCRIPTION OF OCCURRENCE:

On November 14, 1991, at 0825 hours0.00955 days <br />0.229 hours <br />0.00136 weeks <br />3.139125e-4 months <br />, a Maintenan6e Instrument and Controls (I&C) technician began a preventive maintenance (PM) task to open, clean, inspect and close the sample box for the Radiation Monitoring System (RMS) fILl Containment Particulate Radiation Monitor, lRllA. At 0842 hours0.00975 days <br />0.234 hours <br />0.00139 weeks <br />3.20381e-4 months <br /> the same day, during the performance of the PM task, a Containment Purge/Pressure-Vacuum Relief System (CP/P-VR) isolation signal actuated as a result of a high channel spike on lRllA. The associated containment isolation valves were closed at the time and did not change position as a result of the isolation signal. Subsequently, per Technical Specification Table_

3.3-6 Action 20, Technical Specification 3.4.6.1 Action Statement (for Reactor Coolant System leakage detection) was entered.

Technical Specification 3.4.6.1 states:

"The following Reactor Coolant System leakage detection systems shall be OPERABLE:

a. The containment atmosphere particulate radioactivity monitoring system,

b. The containment sump level monitoring system, and

c. Either the containment fan cooler condensate flow rate or the containment atmosphere gaseous radioactivity monitoring system."

Technical Specification 3.4.6.1 Action Statement states:

"With only two of the above required leakage detection systems OPERABLE, operation may continue for up to 30 days provided grab sam~les of the containment atmosphere are obtained and

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LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272. 91-032-00 3 of 4 DESCRIPTION OF OCCURRENCE: (cont'd) analyzed at least once per 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> when the required gaseous and/or particulate radioactivity monitoring system is inoperable; otherwise, be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the.following 30

• hours."

The CP/P-VR _system isolation is an Engineered Safety Feature (ESF)

{JE}. Therefore, on November 14, 1991, at 1211 hours0.014 days <br />0.336 hours <br />0.002 weeks <br />4.607855e-4 months <br /> the Nuclear Regulatory Commission was notified of the automatic actuation signal in accordance.with Code of Federal Regulations 10CFR

50. 72 (b) (2) (ii).

APPARENT CAUSE OF OCCURRENCE:

The root cause of the channel spike is attributed to design inadequacy.

An investigation assessed the activities associated with the PM to determine the cause of the event. It was thought that the spike may have been caused by the lRllA detector cable being disturbed

• during repositioning of the lead shielding around the detector housing. Therefore, the channel trip function was blocked and the detector cable manipulated to determine if there was a malfunction in the cable or detector connection. There was no indication that the cable or detector were malfunctioning. The rags used to cleari the sample box were frisked to determine if the spike had been caused by loose contamination or a hot particle. The*rags were not contaminated.

A review was conducted to determine if other work activities (i.e.,

welding} being performed in the immediate area contributed to the cause of tpe event. There were no such activities being performed at the time of the event.

As indicated by prior LERs .(reference 272/91-001-00), the RMS channels are subject to intermittent spikes due to external influences. To limit the number of possible spurious channel spikes the Maintenance Department Work Standard ("Paperchange"),

for replacement of the 1R11A channel filter ~aper, has been revised to include blocking the lRllA channel trip function as part of the PM.

The lRllA channel was .restored following the investigation. A channel calibration check was comple-ted satisfactorily.

Subsequently, the Action Statement was exited November 14, 1991, at 1105 hours0.0128 days <br />0.307 hours <br />0.00183 weeks <br />4.204525e-4 months <br />.

ANALYSIS OF OCCURRENCE:

The lRllA, Containment Particulate Monitor, (a Nal scintillation type detector, model LFE MD5B} monitors the air particulate gamma

LICENSEE EVENT REPORT CLER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 91-032-00 4 of 4 ANALYSIS OF OCCURRENCE: (cont'd) radioactivity in the Containment atmosphere. **It is used to identify RCS leakage.in conjunction with the containment sump level monitoring system, the cont&1nment fan cooler condensate flow-rate monitors, and the contaiill!lent atmosphere gaseous radioactivity (1R12A) RMS channel.. An alarm signal causes the automatic isolation of the CP/P-VRS.

Air samples. are pulled directly from the Containment atmosphere through filter paper which continuously moves past the lRllA scintillation detector .. After the air sample passei through the filter paper, it go~s through a charcoal cartridge (monitored by the 1R12B monitor) and is then mixed into a fixed shielded volume where it is viewed by the 1R12A noble gas monitor. The air sample is then returned to the Containment. * .

During the lRllA channel spike, RCS leakage within the Containment did not increase, and the corroborating RMS channel (1R41A) was operable and would have provided isolation of the CP/P-VR system if there had been any increase in Containment airborne activity.

Therefore, this event did not affect the health or safety of the public. However, due to the automatic actuation signal of an ESF system, it is reportable in accordance with.Code of Federal Regulations 10CFR 50.73(a) (2) (iv).

CORRECTIVE ACTION:

A channel calibration check was performed satisfactorily and the channel returned to service.

The event was discussed with the appropriate Maintenance I&C RMS qualified technicians.

The Maintenance Department Work Standard "Paperchange" has been revised to provide instructions for blocking the channel trip function.

The design of the entire RMS system is being reviewed and the appropriate design changes will be implemented to enhance the system.

General Manager -

Salem Operations BWL:pc SORC Mtg.91-125