ML18096A413

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LER 91-035-00:on 911127,radiation Monitoring Sys Noble Gas Radiation Monitor 1R12A Alarmed,Resulting in Containment Purge/Pressure Vacuum Isolation Signal.Cause Under Investigation.Detector & Housing cleaned.W/911231 Ltr
ML18096A413
Person / Time
Site: Salem PSEG icon.png
Issue date: 12/31/1991
From: Pollack M, Vondra C
Public Service Enterprise Group
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-91-035, LER-91-35, NUDOCS 9201070217
Download: ML18096A413 (6)
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Public Servi.Ce Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station December 31, 1991 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 LICENSE~ EVENT REPORT 91-035-00 This Licensee 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. However, due ~o the discovery of new information regarding this event, an extension of five (5) days was discussed with and agreed to. by the NRC resident staff.

Sincerely yours,

~A?~c? ,..p~

c.Y<. vondra General Manager -

Salem Operations MJP:pc Distribution 03005:J 95-2189 (10M) 12-89

.~** , U.S. NUCLEAR REGULATORY COMMISSION APPROVED OMB NO. 3150-6104 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 MANA-GEM ENT AND BUDGET, WASHINGTON, DC 20503.

FACILITY NAME (1) DOCKET NUMBER (2) I PAGE 131 Salem Generating Station -

TITLE (4)

Unit 1 !0 I 5 1. 0 I 0 I 0 I 21 71 2 I 1 I0 F 0 I5 ESF Signal Actuation; 1Rl2A RMS Channel Initiated a Containment Vent. Isolation Signal EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) . - OTHER FACILITIES INVOLVED (8)

MONTH DAY YEAR YEAR :tt SE~~~~~~AL \) ~~~~~~ MONTH DAY YEAR FACILITY NAMES DOCKET NUM.BERISl 1 I1 217 9 1 911 - o13 I s - o lo 112 311 *911 0 I 5 I 0 I 0 *1 0 I I I THiS REPORT IS SUBMITTED PURSUANT TO THE R~OUIREMENTS OF 10 CFR §: (Ch*ck ono or mor* of th* following) (11)

OPERATING

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- 50.36lcll21 50.73(11121 lviil OTHER (Specify in Abstrecr below and in Text, NRC Form I--

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LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER AREA CODE M. J~ Pollack - LER Coordinator 610 I 9 3 I 31 91- I 21 0 12 12 COMPLETE ONE LINE FOR EACH COMPONENT F.AILURE DESCRIBED IN THIS REPORT 1131 MANUFAC- MANUFAC*

CAUSE SYSTEM COMPONENT CAUSE SYSTEM COMPONENT TURER TUR ER I *I I I I I I I I I I I I I

.*::1:.:1::*_!j*::.:1:*:.,,*:::.::::_:*:1.::.:-:..:::

I I I I I I I I I I I I I I SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY YEAR EXPECTED SUBMISSION Iii YES (If y*s, compl*t* E~PECTED SUBMISSION DATE!

DATE 115) 0.(3 Of2 9 I 2 ABSTRACT (Li(r1it to 1400 spactJs, i.s., spproximtJttJly fifttJen sing/9-space typewritttJn lines} (16)

On November 27, 1991, at 0042 hours4.861111e-4 days <br />0.0117 hours <br />6.944444e-5 weeks <br />1.5981e-5 months <br />, the Radiation Monitoring s'ystem (RMS) {ILi 1R12A Containment Noble Gas Radiation Monitor channel alarmed resulting in a Containment Purge/Pressure-Vacuum Relief (CP/P-VR) System {BFI isolation signal. Investigation of the event was initiated which included taking a portable Containment air sample. The sample did not indicate any increased activity. The 1R12A RMS channel was declared inoperable and Technical Specification 3.3.3.1 Table 3.3-6 Action 20 was entered on November 27, 1991, at 0334 hours0.00387 days <br />0.0928 hours <br />5.522487e-4 weeks <br />1.27087e-4 months <br />. Investigation of the*root cause of this event is continu1ng. Preliminary results indicate that the 1R12A monitor may have responded to actual radioactivity, the source of which is not presently known. The 1R12A channel detector and detector housing were cleaned and ~ channel calibration check was performed satisfactorily.

The channel was returned to service on November 29, 1991, at 1125 hours0.013 days <br />0.313 hours <br />0.00186 weeks <br />4.280625e-4 months <br />, at which time Technical Specification Table 3.3-6 Action 20 was exited. Investigation to determine the source of the Radon d~ughter products is continuing. Investigation of the 1R12A CP/PV-R System is.elation signal is continuing. Upon completion a supplemental LER will be issued.

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION

' Salem Generating Station DOCKET NUMBER .LER NUMBER PAGE*

Unit 1 5000272 91-035-00 2 of 5 PLANT AND SYSTEM IDENTIFICATION:

Westinghouse - Pressurized Water Reactor Energy Industry Identification System (EIIS) codes-are identified in the text as {xxl IDENTIFICATION OF OCCURRENCE:

Engineered Safety Feature signal initiated from the Radiation Monitoring System Event Date: 11/27/91 Report Date: 12/31/91 This report was initiated by Incident Report No. 91~864.

CONDITIONS PRIOR TO OCCURRENCE:

Mode 1 Reactor Power 100% - Unit Load 1160 MWe -

DESCRIPTION OF OCCURRENCE:

On November 27, 1991, at 0042 hours4.861111e-4 days <br />0.0117 hours <br />6.944444e-5 weeks <br />1.5981e-5 months <br />, the Radiation Monitoring System (RMS) {IL} 1Rl2A Containment Noble Gas Radiation Monitor. channel alarmed resulting in a Containment Purge/Pressure-Vacuum Relief (CP/P-VR) System {BFI isolation signal. Invesiigation 0£ the event was initiated which included taking a Containment air sample. The sample did not indicate any increased activity. The 1R12A RMS channel was declared inoperable arid Technical Specification 3.3.3.1 Table 3.3-6 Action 20 was entered on November 27, 1991, at 0334 hours0.00387 days <br />0.0928 hours <br />5.522487e-4 weeks <br />1.27087e-4 months <br />.*

The CP/P-VR System isolation signal is an Engineered Safety Feature (ESF) {JC}. Therefore, the Nuclear Regulatory Commission was notified of the automatic actuation signal in ~ccordance with Code of Federal Regulations 10CFR 50. 72 (b) (2) (ii) on November 27, 1991, at 0119 hours0.00138 days <br />0.0331 hours <br />1.967593e-4 weeks <br />4.52795e-5 months <br />.

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".

Technical Specification 3.4.6.1 states:

"The following Reactor Coolant System leakage detection systems shal'l be OPERABLE:

a. The containment atmosphere particulate radioactivity monitoring system,

LI.CENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 .. 91-035-00 3 of 5 DESCRIPTION OF OCCURRENCE: (cont'd)-

b. *The containment sump level monite>ring 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:

Investig~tion of the root cause of this event is continuing.

Preliminary results indicate that the 1R12A monitor may have responded to actual radioactivity, the source of which is not presently known.

Prior to the event, on November 26, 1991*, the 1R12A count rate was observed to be trending up.* During this increase, the lRllA Containment Particulate Monitor RMS channel spiked high resulting in a CP/P-VR System isolation signal (see LER 272/91-034-00).

Investigation of the 1R11A event identified 1800 cpm above background on the lRllA filter paper. As discussed in the Analysis of Occurrence section, the 1R11A and 1R12A monitor the same sample of Containment air. The lRllA RMS channel activity was determined to be Pb.:.214 and Bi-214 {naturally occurring Radon daughter products).*

This activity was thought to also be the source of the increase in 1R12A background counts. The 1R12A detector housing and detector were subsequently cleaned, on November 26, 1991, resulting in the lowering of the 1R12A background count rate to a nominally expected value.

The investigation of the November 27, 1991 1R12A event included cleaning the detector housing and detector, *again resulting. in the*

lowering of the 1R12A background count rate to a nominally expected value. Also, a channel calibration check was successfully performed.

A search for leaks, within the Containment, was conducted. An extremely small leak was identified on the Pressurizer Relief -Tank (PRT) rupture disc. This leak was determined to be inconsequential to an increase in Containment airborne activity. An air sample by the PRT did not show an increase in airborne activity.

The 1R12A RMS channel was subsequently returned to service. on November 29, 1991, at 1125 hours0.013 days <br />0.313 hours <br />0.00186 weeks <br />4.280625e-4 months <br />, *at which time Technical Specification Table 3.3-6 Action 20 was exited.

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272. 91-035-00 4 of 5 APPARENT CAUSE OF OCCURRENCE: (cont'd)

On December 5, 1991, at 0230 hours0.00266 days <br />0.0639 hours <br />3.80291e-4 weeks <br />8.7515e-5 months <br />, 1Rl2A RMS channel was taken out of service due to observed readings approaching the channel's warning setpoint. The applicable Action Statement was entered. Containment air samples, as before, did not show any increase in background activity. *Analysis of detector and detector housing smears showed Pb-214, Bi-214 and Rb-88 .. The channel was returned to service and t~e Action Statement exited on December 6, 1991, at 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br />.

ANALYSIS OF OCCURRENCE:

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

Air samples are pulled from the Containment atmosphere through filter paper which continuously moves past the lRllA (Containment Particu-late Radiation Monitor) detector. The air sample then passes through a charcoal cartridge (mon1tored by the 1R12B detector) and is then mixed into a fixed shielded volume where it *is viewed by the 1Rl2A (Containment Noble Gas Radiation ~onitor) detector. The air sample is then returned to the Containment. -

  • The lRllA Containment Particulate.Monitor, (a NaI scintillation type detector, moµel LFE MD5B) monitors the air particulate gamma radio-activity in the Containment atmosphere. It is used to identify Reactor co6lant System (RCS) {AB}. leakage in conjunction with the
  • containment sump level monitoring system, and either the containment fan coolE;!r condensate flow rate or. the containment atmosphere gaseous (1R12A) radioactivity monitoring system.

The 1Rl2A, Containment Noble Gas Monitor, (a geiger-mueller detector) monitors the radioactive noble gas activity in the Containmenf atmosphere. It i~ used to identify RCS leakage in conjunction with the containment sump level monitoring system, and either the containment fan cooler condensate.flow rate monitoring system, or the containment radioactive particulate (lRllA) radioactivity monitoring system.

Both the lRllA and 1Rl2A RMS channels provide an alarm signal which will cause the automatic isolationof the CP/P-:VR System.

At the time of the 1R12A ESF signal actuation, .Containment Purge and Pressure-Vacuum Relief activities were not in progress. The Containment' Ventilation valves were closed. They did not change position as a result of the isolation signal.

During the 1Rl2A event, RCS leakage within the Containment did not increase nor were there any -significant indications of increasing Containment activity based on subsequent air samples~ Therefore, this event did not affect the health or safety of the public.

However, due to the automatic actuation signal of ari ESF system, it is reportable in _accorda_nce with Code of Federal Regulations 10CFR

50. 7 3 (a) ( 2) (iv) .

LICENSEE EVENT REPORT (LER) TEXT CONTiij'UATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 91-035-00 5 of 5 CORRECTIVE ACTION:

The 1R12A channel detectbr and detector*housing were cleaned and a.

channel calibration check was performed satisfactorily. The channel was returned to service on November 29, 1991, at 1125 hours0.013 days <br />0.313 hours <br />0.00186 weeks <br />4.280625e-4 months <br />, at which time Technical Specification Table 3.3-6 Action 20 was exited.

Investigation to determine the source of the Rb-88 and Radon daughter products is continuing.

Investigation 9f the 1R12A CP/PV-R System isolation signal is continuing. Upon completion a supplemental LER will be issued.

The PRT rupture disc leak will be repaired. A work order has .been initiated.

1/cJC7~0~

/?CA..-

G~ral Mana~er -

Salem Operations MJP:pc SORC Mtg.91-132

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