ML18096B285

LER 92-026-01:on 921213,30 & 930125,ESF Actuations Initiated from Rms.Caused by Increased Containment Activity.Maint Testing of 1R11A Rms Channel Completed & 1PS1 Valve Leak Stopped Via Closure of Maint Valves upstream.W/930218 Ltr

ML18096B285
Person / Time
Site:	Salem
Issue date:	02/18/1993
From:	Pollack M, Vondra C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-92-026, LER-92-26, NUDOCS 9302230322
Download: ML18096B285 (6)

Text

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Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038- .

Salem Generating Station February 18, 1993

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 92-026-01 This Licensee Event Report supplement is being submitted pursuant to the requirements of the Code of Federal Regulations 10CFR 50.73. It addresses a fourth 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, General Manager -

Salem Operations

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MJP:pc Distribution

._220049 The Energy People __.. _.

9302230322 930218 95-2189 (10M) 12-89 PDR ADOCK 0500027~

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• • Aj NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 3150-0104 (6-89)

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 OF MANAGEMENT AND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) I PAGE (3)

Salem TITLE (4)

GPn°Y~rina Station - Unit 1 Io 15 I o Io I o I  ? I7 h I 1foF nl "

En~ineered Safetv Feature actuations initiated from the Radiation Mnnitorina ~,,~~--

EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED(B) -,

MONTH DAY YEAR YEAR tt: sE,e~~~~~AL Jt ~~~~~~ MONTH DAY YEAR FACILITY NAMES DOCKET NUMBER(S) oli .-21-SLlL.3 912 -ol 216- ol1 01211s913 THIS REPORT IS SUBMITTED PURSUANT TO THE R~QUIREMENTS OF 10 CFR §: (Check one or more of the following) (11)

OPERATING

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OTHER (Specify in Abstr*ct bt1/ow and in Text, NRC Form 366A)

- &0.73(*112)(ii) 50.73(*112lliill LICENSEE CONTACT FOR THIS LER (12)

--- 60.73(o)(2)(vliil(BI 60.73(o)(2)(xl NAME TELEPHONE NUMBER AREA CODE M. J. Pollack - LER Coordinator COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (131 MANUFAC- MANUFAC-*

CAUSE SYSTEM COMPONENT TUR ER TURER I I I I I I I I I I I I. I I I I I  :::ii::::i*:::::::::*::ii:::..:::,::i::*:.:::j.*::*-i - I I I I I I I I I I I SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY YEAR EXPECTED t--i L *-~.:. . . .sg~~s~11~1N I I YES (If y~,-.,~;,,pl*t* EXPECTED SUBMISSION DATE) lvl NO I I I ABSTR11hf~ir 't'.E°R'paaeiclres~e~ fif4n 'E:;.gine~re'~r' S~f ~ty Feature ( ESF) actuations initiated through the lRllA Radiation Monit.oring System (RMS) channel which monitors the Containment atmosphere* for particulate activity. The signals were for Containment Purge/Pressure-Vacuum Relief (CP/P-VR)

System isolation. At the time of the events, the associated valves were closed and did not change position. On 12/13/92, at 0535 hours0.00619 days <br />0.149 hours <br />8.845899e-4 weeks <br />2.035675e-4 months <br /> and 0658 hours0.00762 days <br />0.183 hours <br />0.00109 weeks <br />2.50369e-4 months <br />, on 12/30/92, at 1452 hours0.0168 days <br />0.403 hours <br />0.0024 weeks <br />5.52486e-4 months <br />, and on 1/25/93 at 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br />, the lRllA RMS channel increased to the alarm setpoint (60,000 cpm) resulting in CP/P-VR System isolation signals. Investigation determined that the lRllA RMS channel was responding to actual increases in containment airborne radioactivity; i.e., Rb-88 activity (half life of 17. 8 minutes) which is a decay product of Kr-88, a fission product. After the first 3 events, a previously identified lPSl Pressurizer Spray air operated valve bonnet leak appeared to contribute to the source of the increased activity. The valve bonnet leak had been stopped_yia closure of the maintenance valves upstream and downstream and insertion of temporary sealant. The lPSl valve will be repaired at the next outage of sufficient duration. Following th~ __l/25/93 event, investigation identified that pipe flange leakage, immediately upstream of the Raactor head vent manual isolation valve, 1RC900 existed. The flange leak was stopped through installation of a temporary modification (leak repair clamp). Investigation to identify additional source(s) of Containment gaseous activity is continuing.

NRC Form 366 (6-89)

LICENSEE EVENT REPORT-(LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 92-026-01 2 of 5 PLANT AND SYSTEM IDENTIFICATION:

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

IDENTIFICATION OF OCCURRENCE:

Engineered Safety Feature actuations initiated from the Radiation Monitoring System Event Dates: 12/13/92, 12/30/92 and 1/25/93 Report Date: 2/18/93-This supplemental LER was initiated by Incident Report No.93-067 which identified a fourth Engineered Safety Feature signal actuation due to a similar cause. The original LER addressed events discussed in IRS92-819 a~g .~2~865.

CONDITIONS PRIOR TO OCCURRENCE:

12/13/92 - Mode 1 Reactor.Power 100% - Unit Load.1151 MWe On 12/12/92, at 0914 hours0.0106 days <br />0.254 hours <br />0.00151 weeks <br />3.47777e-4 months <br />, power was reduced to 90% due to Circulating Water System high delta T. -At *1a12-*hours (that day), a power increase to full power commenced and was reached on 12/13/-9,2._...at 0650 hours0.00752 days <br />0.181 hours <br />0.00107 weeks <br />2.47325e-4 months <br />.

12/30/92 - M_5)d.e 1:.. -Reactor Power 90% - Unit Load 1010 MWe On 12/36/92, prior to the ESF event, power was being increased from 90% to full power. The Unit had previously been removed from service due to Circulating Water system problems. --~ --

1/25/93 - Mode 1 Reactor Power 99% - Unit Load 1100 MWe On 1/25/93, prior to the ESF event, power was being increased from 88% to full power. The Unit had been removed from service for planned maintenance and experienced a manual reactor trip (LER 272/93-002-00) during shutdown on 1/16/93. Power ascension had begun on 1/23/93.

DESCRIPTION OF OCCURRENCE:

This LER addresses four (4) Engineered Safety Feature (ESF) actuations initiated through the Radiation Monitoring system (RMS)

{IL}. The signals were for Containment Purge/Pressure-Vacuum Relief (CP/P-VR). -system {BF} isolation. The associated isolation valves were closed prior to each event, and therefor=J did not change

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 92-026-01 3 of 5 DESCRIPTION OF OCCURRENCE: (cont'd) position. Per Code of Federal Regulations 10CFR 50.72(b) (2) (ii), the Nuclear Regulatory Commission (NRC) was notified of the four (4) events.

On December 13, 1992, at 0535 hours0.00619 days <br />0.149 hours <br />8.845899e-4 weeks <br />2.035675e-4 months <br />, following a power increase from 99% to 100%, the lRllA RMS channel alarmed actuating a* CP/P-VR System.

isolation. It was initially assessed to be the result or* a channel instrumentation spike; however, further investigation showed it was due to increased Containment airborne activity. Following the actuation, the alarm was cleared and the channel was left in service. At 0658 hours0.00762 days <br />0.183 hours <br />0.00109 weeks <br />2.50369e-4 months <br />, that day, the lRllA RMS channel increased from 35,000 cpm to the alarm setpoint (60,000 cpm) resulting in another CP/P-VR System isolation signal. After this alarm actuation the count level trended back to 35,000 cpm.

The lRllA RMS channel monitors the containment atmosphere for particulate activity by filtering a sample of containment air.

Investigation determined that the lRllA RMS channel was functioning in accordance with its design. Analysis of the sample filter paper showed that the alarm signal was due to Rb-88 activity. Rb-88 has a half life of 17.8 minutes. It is a decay product of Kr-88 which is a fission product. Investigation to identify the source of the activity was initiated.

On December 30, 1992, at 1452 hours0.0168 days <br />0.403 hours <br />0.0024 weeks <br />5.52486e-4 months <br />, during power ascension from 90%

to full power, the lRllA RMS channel indication increased from 35,000 cpm to the alarm setpoint resulting in a CP/P-VR System isolation signal. Following the alarm the channel count rate trended back to 35,000 cpm. The alarm was again shown to be due to Rb-88.

On January 25, 1993, at 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br />, during power ascension from 88%

• to full power,_ the lRllA RMS channel indication increased from 35,000 cpm to the alarm setpoint resulting in a CP/P-VR System isolation signal. Following the alarm, the Containment Fan coil Units were put in low speed reducing containment airborne particulate activity. The channel count rate trended back to 25,000 cpm. The alarm was again shown to be due to Rb-88.

APPARENT CAUSE OF OCCURRENCE:

The cause of the lRllA RMS channel ESF signal actuations is increased Containment activity.

Investigation of the' first three (3) ESF actuations indicated that a previously identified bonn~t leak on the lPSl Pressurizer Spray air oper_ated_valve_was the probable source of the increased activity.

The maintenance valves upstream and downstream of the lPSl valve had been closed isolating the lPSl valve. As identified above, a fourth ESF actuation occurred on January 25, 1993. Investigation of this event identified pipe flange leakage immediately upstream of the

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LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 92-026-01 4 of 5 APPARENT CAUSE OF OCCURRENCE: (cont'd)

Reactor head vent manual isolation valve 1RC900 {AB}. The flange leak was stopped with a temporary modification (leak repair clamp).

Investigation to identify additional source(s) of Containment gaseous activity is continuing. To date, specific areas checked include the Pressurizer area and e~ch general elevation area.

ANALYSIS OF OCCURRENCE:

The lRllA Containment Particulate Mani tor I .. (a Na! scintillation type detector, model LFE MD5B) monitors air particulate gamma radio-activity in the Containment atmosphere. In Modes,.1 through 4, 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. In Mode 6, it is used to provide indication of a fuel handling accident and early Containment isolation in the event of an accident.

The lRllA RMS channel provides an alarm signal which will cause automatic isolation of the CP/P-VR System. Isolation of the CP/P-VR System is an ESF to mitigate the release of radioactive material to the environment after a design basis accident.

A review of lRllA RMS channel data show the alarms were not the result of spurious channel spiking. Routine containment airborne radioactivity monitoring, by Radiation Protection, confirms the l*

presence of sufficient Rb-88 to cause the alarm. Unidentified leak rate calculations (conducted by Operations} show a leak rate of 0.2

---~-gpm. The* Technical Specification limitation on unidentified leakage is 1 gpm.

The lRllA RMS-. channel is functioning per design. It has identified higher than normal airborne particulate activity in Containment. The channel ESF isolation capability is functional. 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:

Maintenance testing of the lRllA RMS channel was completed. No channel failure mechanisms were identified.

The lPSl valve leak has been stopped via closure of the maintenance valves upstream and downstream of the lPSl valve and insertion of temporary sealant. ' The lPSl valve will be repaired at the next 0

outage of sufficient duration.

LICENSEE'EVENT REPORT-(LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 92-026-01 5 of 5 CORRECTIVE ACTION: (cont'd)

The flange leak upstream of the 1RC900 valve was stopped through installation of a leak repair clamp in accordance with temporary modification procedures.

Investigation to identify other additional source(s) of Containment gaseous activity is continuing. Additional minor gaseous leaks have been identified and will be repaired. The effect on Containment particlate atmosphere will continue to be monitored.

/L ~/'-

General Manager -

Salem Operations MJP:pc SORC Mtg.93-015

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