ML18096A747

LER 92-007-01:on 920306 & 0429,radiation Monitoring Sys Channel 1R11A Spiked High,Resulting in ESF Signal Actuations.Caused by Design,Const,Mfg & Installation Error. Channel Calibr & New Detector ordered.W/920528 Ltr

ML18096A747
Person / Time
Site:	Salem
Issue date:	05/28/1992
From:	Pollack M, Vondra C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-92-007, LER-92-7, NUDOCS 9206050084
Download: ML18096A747 (6)

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• Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station May 28, 1992 U. s. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Dear sir:

SALEM GENERATING STATION LICENSE NO. DPR-70 DOCKET NO. 50-272 UNIT NO. 1 SUPPLEMENTAL LICENSEE EVENT REPORT 92-007-01 This Licensee Event Report supplement is being submitted pursuant to the requirements of the Code of Federal Regulations 10CFR 50.73. It addresses a second event which has the same root cause as the first event. Both events are reportable per 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,

c. A Vondra General Manager -

Salem Operations MJP:pc Distribution

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• NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION (6-89) APPROVED OMB NO. 3150-0104 EXPIRES: 4/30/92 ESTIMATED BURDEN PER RESPONSE TO COMPLY WTH THIS INFORMATION COLLECTION REQUEST: 50.0 HRS. FORWARD LICENSEE EVENT REPORT (LERI COMMENTS REGARDING BURDEN ESTIMATE TO THE RECORDS

• , AND REPORTS MANAGEMENT BRANCH (P-530). U.S. NUCLEAR REGULATORY COMMISSION, WASHINGTON, DC 20555, AND TO THE PAPERWORK REDUCTION PROJECT (3150-0104). OFFICE FACILITY NAME (1)

Salem Generating Station - Ul:iit,l I

OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

DOCKET NUMBER (2) o 1s I o Io I o 12 I 712 I

1 loF PAGE 131 o1s TITLE (4) 2 ESF Signal Actuations - Rad Moniitor Channel Spikes EVENT DATE (5) LEA NUMBER 16) REPORT DATE 17) OTHER FACILITIES INVOLVED (B)

MONTH DAY YEAR YEAR ttf SEQUENTIAL NUMBER [) REVlSION NUMBER MONTH DAY YEAR FACILITY NAMES DOCKET NUMBER(S) 01s1010101 I I ol 3 016 9 2 9 I 2 - ol o I 1 - o-11 ols THIS REPORT IS SUBMITTED PURSUANT TO THE R~QUIREMENTS OF 10 CFR 21 8 91 2

§: (Ch*ck on* or mor* of th* following)(11) o I 5 Io Io I o I I I OPERATING MODE (9) l 20.402(b) 20.4051c)

,_ x 50.73(1)(2J(iv) 73.71(b)

POWER LEVEL (10) I 1 I 010 20.4061*)(1 )(i) 20.405(1)(1)(ii) 50.3B(c)(1) 50,3B(c)(2) -- 50.73(1)(2)(v) 50.73(1)(2)(vii) 73.71(c)

OTHER (Specify in Abstroct below and in Text, NRC. Form 20.406(1)(1 )(iii) 50.73(1)(2)(;) 60.73(1)(2)(viiil(A) 366AI

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LICENSEE CONTACT FOR THIS LEA (12)

NAME TELEPHONE NUMBER AREA CODE M. J. Pollack - LER Coordinator 61 O I 9 3 f 3 I .9 f - 12 IO f 2 12 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT 113)

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• • -:*: ........  :::-:-:*:*:* I I I ';::....1*11':._::...*1;.!.!:i_l::.**:**:.,-_*:.-:1 I I I I I I I .... I I I I SUPPLEMENTAL REPORT 'EXPECTED 114) MONTH DAY YEAR EXPECTED bi SUBMISSION I YES (If v*s. compl*t* EXPECTED SUBMISSION DATE! NO DATE (151 I I I ABSTRACT (Limit ro 1400 spaces. i.e., approxima.tefy fifteen single-spsce*type~ritten lines) (161 This LER addresses 2 Engineered Safety Feature {ESF) signals initiated by the 1R11A Containment Particulate Radiation Monitoring system (RMS)

Monitor channel. The signals were for Containment Purge/Pressure-Vaouum Relief (CP/P-VR) System isolation. On 3/6/92, the 1R11A RMS channel momentarily spiked high_resulting in a CP/P-VR System isolation signal.

Channel indication returned to normal after the spike. The 1Rl1A RMS channel was declared inoperable and an investigation into the cause of the event was initiated. Investigation included checking the detector cable for insulation resistance and for continuity. Results were satisfactory. The event could not be reproduced. The channel was returned to service on 3/7/92. On 4/29/92, the 1R11A RMS channel spiked, again resulting in a CP/P-VR System isolation signal. During this event, Containment Purge was in progress. Upon initiation of the isolation signal the containment Purge valves closed per design. The root cause of both lRllA RMS channel ESF signal actuations is "Design, Construction, Manufacturing/Installation" error. The detector can exhibit ground loop conditions. A successful 1R11A RMS channel calibration was completed after the second 1R11A channel spike. On May 26, *1992' the channel was returned to service. A new detector has been ordered from the manufacturer. Upon receipt, it will be installed. A review will be conducted of other RMS channel detectors to determine if they too have a ground loop concern.

NRC Form 366 (6-89)

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 92-007-01 2 of 5 PLANT AND SYSTEM IDENTIFICATION:

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

IDENTIFICATION OF OCCURRENCE:

Two Engineered Safety Feature signal actuations; Radiation Monitoring System channel spikes Event Dates: 3/06/92 and 4/29/92 Report Date: 5/28/92 This report was initiated by Incident Report Nos.92-167 and 92-280.

CONDITIONS PRIOR TO OCCURRENCE:

3/6/92: Mode 1 Reactor Powet 100% - Unit Load 1160 MWe 4/29/92: Reactor defueled - 10 h Refueling outage in progress DESCRIPTION OF OCCURRENCE:

This LER addresses two (2) Engineered Safety Feature (ESF) signals initiated by the lRllA Containment Particulate Radiation Monitoring System (RMS) {IL} Monitor* channel. The signals were for Containment Purge/Pressure-Vacuum Relief (CP/P-VR) System {BF} isolation.

On March 6, 1992, at 1926 hours0.0223 days <br />0.535 hours <br />0.00318 weeks <br />7.32843e-4 months <br />, the lRllA RMS channel momentarily spiked high resulting in a CP/P-VR system isolation signal. Channel indication returned to normal after the spike. The lRllA RMS channel was declared inoperable and an investigation into the cause of the event was initiated. The isolation valves were closed at the time and did not change position as a result of the isolation signal.

Technical Specification 3.3.2.1, 3.3.3.1, 3.3.3~9 and 3.4.6.l Action Statements were entered.

At about the time of this event, a Chemistry technician was obtain_ing a Containment grab sample using the lRllA sample piping. The Chemistry technician was interviewed and his work procedure reviewed; however, it could not be shown that his activities contributed to the cause of the channel spike.

Investigation of the March 6, 1992 event included checking the detector cable for insulation resistance (i.e., meggered the cable) and for continuity. Results were satisfactory. Also, the cable was manipulated, at the detector and the ratemeter drawer, in an attempt to reproduce the channel spiking; however, it could not be reproduced. The channel was returned to service and the Technical Specification Action Statements exited on March 7, 1992, at 0103

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 92-007-01 3 of 5 DESCRIPTION OF OCCURRENCE: {cont'd) hours. Based on an engineering assessinent of investigation results, the lRllA detector was to be replaced.

On April 29, 1992, at 0736 hours0.00852 days <br />0.204 hours <br />0.00122 weeks <br />2.80048e-4 months <br />, the lRllA RMS channel spiked, again resulting in a CP/P-VR System isolation signal. During this event, Containment Purge was in progress. Upon initiation of the isolation signal the Containment Purge valves closed per design.

The CP/P-VR System isolation signal is an Engineered Safety Feature (ESF). Therefore, the Nuclear Regulatory Commission was notified in accordance with Code of Federal Regulations 10CFR 50.72(b) (2) (ii) on March 6, 1992, at 1944 hours0.0225 days <br />0.54 hours <br />0.00321 weeks <br />7.39692e-4 months <br /> and April 29, 1992, at 1034 hours0.012 days <br />0.287 hours <br />0.00171 weeks <br />3.93437e-4 months <br />, upon each ESF signal.

Technical Specification Table 3.3-6 Action 20 states:

"With the number of channels OPERABLE less than required by the Minimum Channels OPERABLE requirement, comply with the ACTION requirements of Specification 3.4.6.1 11

• Technical Specification 3.4.6.1 states:

"The following Reactor Coolant Sys,tem 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 samples of the containment atmosphere are obtained and 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 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />."

APPARENT CAUSE OF OCCURRENCE:

The root cause of both lRllA channel ESF signal actuations is attributed to "Design, Construction, Manufacturing/ Installation" error, as per NUREG 1022, "Licensee Event Report System".

• LICENSEE EVENT REPORT (LER) TEXT CONTINUATION SaJ_em Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 92-007-01 4 of 5 APPARENT CAUSE OF OCCURRENCE: (cont'd)

Subsequent discussion with the vendor (Nuclear Research corporation) identified that~ "older series of MD-3, 4, 5 detectors, can exhibit ground loop conditions which contributes to spurious count rates (spiking, transients). This is caused by connections between chassis ground and signal ground at* the detector and rate meter. 11 Troubleshooting after the second channel spike did not identify any failed components. A lRllA channel calibratio.n was successfully completed.

lRllA RMS channel spiking has occurred periodically in the past in which a specific cause could not be identified (e.g., reference LER 272/91-001-00). It is believed that those events were also caused by the ground loop condition discussed above.

ANALYSIS OF OCCURRENCE:

Isolation of the CP/P-VR System is an ESF. It mitigates the release of radioactive material to the environment after a design basis accident.

• Air samples are pulled from the Containment through filter pap1ar which continuously moves past the. lRllA (Containment Particulate Radiation Monitor) detector. The air sample then passes through a charcoal cartridge (monitored by the 1R12B detector) and is mixed into a fixed shielded volume where i t is viewed by the 1R12A (Containment Noble Gas Radiation Monitor) detector. The air sample is then returned to the Containment.

The lRllA Containment Particulate Monitor, (a Na! scintillation type detector, model LFE MD5B) monitors air particulate gamma radio-

• activity in the Containment atmosphere. It is used to identify Reactor Coolant System (RCS) {AB} leakage in conjunction with the containment sump level monitoring system, and either the containment fan.cooler condensate flow rate or the containment atmosphere gaseous (1R12A) radioactivity monitoring system.

• Both the lRllA and 1R12A RMS channels provide an alarm signal which will cause the automatic isolation of the CP/P-VR System.

During these events, airborne activity within Containment did not increase. Also, the CP/P-VR System isolation valves functioned per design. Therefore, this event did not affect the health or safety of the public. However, due to the automatic actuation signal of an ESF system, they are reportable in accordance with Code of Federal Regulations 10CFR 50.73(a) (2) (iv).

CORRECTIVE ACTION:

A successful lRllA RMS channel calibration was completed after. the r

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 92-007-01 5 of 5 CORRECTIVE ACTION:

second lRllA channel spike. On May 26, 1992, at 0306 hours0.00354 days <br />0.085 hours <br />5.059524e-4 weeks <br />1.16433e-4 months <br />, the channel was returned to service.

A new detector has been ordered from the manufacturer.which does not have the ground loop problem (see Apparent Cause of Occurrence section). Upon receipt, it will be installed.

A review will be conducted of other RMS channel detectors to determine if they too have a ground loop concern.

The circumstances surrounding the first lRllA ESF signal actuation event has been reviewed with applicable Chemistry Department personnel.

General Manager ~

Salem Operations MJP:pc SORC Mtg.92-063