ML18100A656

LER 92-026-02:on 921213,30 & 930125,ESF Actuations Initiated by 1R11A Radiation Monitoring Sys Channel.Caused by Equipment Failure.Maint Testing of 1R11A Channel Completed. Listed Leaking Valves stopped.W/931007 Ltr

ML18100A656
Person / Time
Site:	Salem
Issue date:	10/07/1993
From:	Pollack M, Vondra C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-92-026-01, LER-92-26-1, NUDOCS 9310180314
Download: ML18100A656 (6)

Text

e PS~G Public Service Electric and Gas Company P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station October 7, 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 92-026-02 This supplemental Licensee Event Report is being submitted pursuant to Code of Federal Regulations lOCF~ 50.73. The report has been modified based upon investigation results and identifies the current status of corrective actions.

Sincerely yours,

c. A. Vondra General Manager -

Salem Operations MJPJ:pc Distribution 150057

~fiA 0 1~noa14 931007 s OCK 05000272

. PDR The power is in your hands. :rE. z..i.

95-2189 REV 7-92

\fl 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 OF M_ANAGEMENT AND BUDGET, WASHINGTON, DC 20503, FACILITY NAME (1) DOCKET NUMBER (21 I PAGE 131 Salem Generating Station - Unit 1 o 1s101010121712 1!0F 015 TITLE (4)

ESF Actuations Initiated From The Radiation Monitoring System.

EVENT DATE (5) LER NUMBER (6) REPORT DATE (7) OTHER FACILITIES INVOLVED (8)

MONTH DAY YEAR YEAR  :::::::::::SEQUENTIAL o::;:;:: REVISION DAY YEAR FACI L/TY NAMES DOCKET NUMBER(S)

• '.*'.*:*:*:* NUMBER .;:;:;:::: NUMBER MONTH i I2 i I 3 9 2 9 I 2 - o l 2 l6 - oI2 i l o o 17 I 9 3 OPERATING THIS REPORT IS SUBMITTED PURSUANT TO THE R~QUIREMENTS OF 10 CFR §: (Check one or more of lh* following) (11)

MODE (9) 1 x I ,_

20.402(b) 20,405(c) 50.73(1)(2)(iv) 73.71(b)

POWER LEVEL (10) l I O I O 1--

20.406(1)(1 )(i) 20.405(1)(1 )(ji) 50.36(c)(1) 50.36(c)(2) 50.73(1)(2)(v) 50.73(1J(2)(viil 73.71(c)

OTHER (Specify in Absrrocl btJ/ow tJnd in Tt1xt, NRC Form lllilll=

20.405(1)(1 )(iii) 50.73(1)(2J(i) 50.73(1)(2)(viiil(A) 366A) 20.405(1)(1)(lv) 50,73(1Jl2llii) 50.73(1) (2) (viii) (B) 20.406(1)(1 )(v) 50.73(1)(2)(111) 50.73(1)(2)(x)

LICENSEE CONTACT FOR THIS LER (12)

NAME TELEPHONE NUMBER AREA CODE M. J. Pollack - LER Coordinator COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

MANUFAC* MANUFAC*

CAUSE SYSTEM COMPONENT TUR ER TUR ER B W 11 I 210 y I I I I I I I I I I I I I I I I I I I I I SUPPLEMENTAL REPORT EXPECTED (14) MONTH DAY YEAR EXPECTED

~NO SUBMISSION l YES (If yes, compl*le EXPECTED SUBMISSION DA TEI DATE 1151 I I ABSTRACT (Limit to 1400 spactJs, i.tJ., tJpproximtJtBly fiftatJn single*spact1 typ11writt1Jn /int1sl (16)

This supplemental LER addresses investigation results and identifies the '

current status of corrective actions associated with 4 Engineered Safety Feature (ESF) actuations initiated by the lRllA Radiation Monitoring system (RMS} channel. The lRllA RMS Channel monitors the Containment atmosphere for particulate activity. The ESF 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. Two of the events occurred on 12/13/92, one on 12/30/92, and one on 1/25/93. 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. Contributing leakage sources included: 1) lPSl Pressurizer Spray air operated valve bonnet leak; 2) pipe flange leakage, immediately upstream of the Reactor head vent manual isolation valve, 1RC900; 3) Pressurizer manway leakage past its gasket seal; and 4) Pressurizer Relief Tank rupture disk pinhole leakage.

NRC Form 366 (6-89)

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 92-026-02 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: 10/7/93 This supplemental LER addresses investigation results and identifies the current status of corrective actions. The prior LER supplement and original LER addressed events were initiated based on Incident l

Reports92-819, 92-865 and 93-067.

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 1812 hours0.021 days <br />0.503 hours <br />0.003 weeks <br />6.89466e-4 months <br /> (that day), a power increase to full power commenced and was reached on 12/13/92 at 0650 hours0.00752 days <br />0.181 hours <br />0.00107 weeks <br />2.47325e-4 months <br />.

12/30/92 - Mode 1 Reactor Power 90% - Unit Load 1010 MWe On 12/30/92, 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 therefore, did not change

/

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 92-026-02 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 of a channel instrumentation spike; however, further investigation showed it was due to increased Containment airborne activity. Fol-lowing 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 Qpm) 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 o_f 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 root cause of the ESF events is equipment failure. Small leaks from various components had led to increased Containment airborne activity.

Investigation of the first three (3) ESF actuations indicated that a previously identified bonnet leak on the lPSl Pressurizer Spray air operated 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. Also, the lPSl valve was leak repaired. Investigation of the fourth ESF actuation identified pipe

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 92-026-02 4 of 5 APPARENT CAUSE OF OCCURRENCE: (cont'd) flange leakage immediately upstream of the 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 has been completed. Those other sources identified include leakage past the Pressurizer manway*s gasket seal and several pinhole leaks on the Pressurizer Relief Tank (PRT) rupture disk.

Temporary leak repair of the Pressurizer manway was completed. This reduced the Containment Rb-88 activity to below the lRllA RMS channel warning setpoint. Permanent repairs will include gasket and diaphragm replacement and repair of any identified damage during the Unit 1 eleventh refueling outage (which began on October 2, 1993).

System Engineering completed a Deficiency Report (930217211) which included a safety evaluation. The evaluation concludes that the pinholes do not inhibit the rupture disk from performing its intended function. Based on this assessment, the PRT rupture disk will be replaced during the Unit 1 eleventh refueling outage.

ANALYSIS OF OCCURRENCE:

The lRllA Containment Particulate Monitor, (a NaI 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.

At the time of these ESF actuations, the lRllA RMS channel provided an alarm signal which caused automatic isolation of the CP/P-VR System. Isolation of the CP/P-VR System is designed to mitigate the release of radioactive material to the environment after a design pasis accident. Since the occurrence of these ESF actuations, an engineering review was conducted to determine the necessity for the lRllA RMS channel to have this function. It was concluded that in Modes 1 - 5 the lRllA channel does not require this function.

Therefore, the ESF function has been disabled during plant operation in Modes 1 - 5. This.eliminates unnecessary challenges of the CP/PV-R ESF System.

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 presence of sufficie.nt Rb-88 to cause the alarm. Unidentified leak

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station DOCKET NUMBER LER NUMBER PAGE Unit 1 5000272 92-026-02 5 of 5 ANALYSIS OF OCCURRENCE: (cont'd) 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 functioned per design. It has identified J' higher than normal airborne particulate activity in Containment. The channel ESF isolation capability was 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 was 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 during the Unit 1 eleventh refueling outage.

The flange leak upstream of the 1RC900 valve was stopped through installation of a leak repair clamp in accordance with temporary modification procedures. Permanent repair will be completed during the Unit 1 eleventh refueling outage.

Permanent repair of the Pressurizer manway gasket seal and replacement of the PRT rupture disk will be completed during the Unit 1 eleventh refueling outage.

Salem Operations MJP:pc SORC Mtg.93-089