ML18096A672

LER 92-006-00:on 920329,0401 & 0331,ESF Signals Initiated by Radiation Monitoring Sys Due to Paper Tear Alarm.Caused by Design Defect.Signals Added to Downscale Failure Alarms & Channel Filter Paper Motor replaced.W/920427 Ltr

ML18096A672
Person / Time
Site:	Salem
Issue date:	04/27/1992
From:	Pollack M, Vondra C Public Service Enterprise Group
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-92-006-01, LER-92-6-1, NUDOCS 9205050189
Download: ML18096A672 (6)

Text

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• Public Service Electric and Gas Com*pany P.O. Box 236 Hancocks Bridge, New Jersey 08038 Salem Generating Station April 27, 1992

u. s. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555

Dear Sir:

.I SALEM GENERATING STATION LICENSE NO .. DPR-75 DOCKET NO.* 50-311 UNIT NO. 2 LICENSEE EVENT REPORT 92-006~00 This Licensee Event Report is being submitted pu~~uan~ to the re.quirements of* the Code of .Federal Regulations lOCFR 50.73(a) (2) (iv). This report is required to. ~e issued within thirty (30) days of event discovery.

C. A. Vondra General Manager -

Salem Operations MJP:pc

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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 (11 DOCKET NUMBER 121 I P 131 Salem Generating Station TITLE (41 *

~-Unit 2 Io I 5 I o I o I o I 31 11 l 1 loF 0 I 5 3 ESF Actuation -Signals For Containment Ventilation Isolatdicim Due To Design 0

EVENT DATE 151 LER NUM BER (6) REPORT DATE (7) OTHER*FACILITIES INVOLVED (Bl MONTH DAY YEAR YEAR tt~ SE~~~~~lfL [ : ) ~~~~~~ MONTH DAY YEAR FA.Cl LITY NAMES DOCKET NUMBERISJ 01s1010101 I 1.

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60.73(o)(2)(viiiJIAJ 60.73(o)l2JlvliiJIBI 60,73JoJ(2llxJ below and in Texr, NRC Form 366AJ LICENSEE CONTACT FOR THIS LER 1121 NAME - TELEPHONE NUMBER AREA CODE M. J. Pollack - LER Coordinator COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)

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.SUBMISSION DATE 1151 I I I This LER addresses 3 Engineered Safety Feature (ESF) signals initiated by the Radiation Monitoring System (RMS). The signals were for Containment Purge/Pressure-Vacuum Relief (CP/P-VR) System isolation.

The isolation valves were closed at the time of the signals and did not change position. On.3/29/92 and 4/01/92, the 2RllA Containment Particulate RMS Monitor channel initiated CP/P-VR System isolation signals. Each of these signal actuations was the result of a "paper tear alarm". On 3/31/92, the 2R41C Plant Vent Noble Gas Monitor charinel alarmed on "low flow". The ~oot cause of these 3 events is design. During the recent Unit 2 refueling outage (2R6), RMS channels were upgraded including the tying together of downscale alarms with the CP/P-VR System isolation signal circuitry. Subsequently, it has been shown that actuation of CP/P-VR System isolation on these downscale failures is not necessary; therefore, those failure alarms which were tied to the CP/P-VR System isolation circuit have been returned to original design (i.e., alarm only). The 2RllA paper tear qlarm actuated due to failure of the paper take-up motor to maintain adequate tension. The motor was replaced. The 2R41C channel low flow alarm actuated d~e to a momentary decrease of flow as a result of concurrent work. The Auxiliary Building Ventilation System supply and exhaust fans were being swapped. Also, Che~istry had disconnected the Plant Vent composite iodine and particulate sample pump downstream connection which pulls its sample from the 2R41 sample line.

NRC Form 366 16-89)

LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station* DOCKET NUMBER LER NUMBER PAGE Unit 2

~~~~~~~~~~~~~~~~~~~-

5000311 _ _ _9 2--_Q_Q_G-_Q_Q________~___ gJ___~---*_

PLANT AND SYSTEM IDENTIFICATION:

Westing~ouse - Pressurized Water Reactor

.Ener~y Industry tdent{fication System (EIIS) codes are identified in the text as {xx}

IDENTIFICATION OF OCCURRENCE:

3 Engineered Safety Feature actuation signals for Containment Ventilation Isolatibn Ev~nt Dates: 3/29/92, 3/31/92 and 4/01/92 Report Date~ 4/27/92 This report was initiated by Incident Report Nos.92-215, 92-218 and 92-220.

CONDITIONS PRIOR TO OCCURRE_N~$:_

March *2*9, 1992: Mode 5 (Cold Shutdown) (Gth Refueling/Maintenance Outage in Progress)

• March 31, 1992: Mode 5 April 01, 1992: Mode *4 (Hot Shutdown)

DESCRIPTION OF OCCURRENCE:

This LER addresses three (3) Engineered Safety Feaiure fES~) signals initiated by the Radiation Monitoring System (RMS) {ILi. The signals were for Containment Purge/Pressure-Vacuum Relief (CP/P-VR) System

{BF) isolation., The isolation valves were closed at the time of the signals .and did n9t change position.

On March 29, 1992r at 1440 hours0.0167 days <br />0.4 hours <br />0.00238 weeks <br />5.4792e-4 months <br />, the 2R11A Containment Particul~te RMS Monitor channel initiated a CP/P-VR System isolation signal.

Alarms included annunciator panel 2RP4 "Vent Isolation" and console alarm "Phase A and Cont Vent Isolation Operate". Also, the 2R11A green normal light was off. The 2R11A RMS channel was declared inoperable. Inve~tigation revealed that the ESF signal actuation was the result of a "paper tear alarm". The 2R11A RMS channel filter paper had loosened. After the filter paper was tightened onto its*

take-up reel the alarm cleared. Upon direction from System Engin~ering, a daily.inspection ~~s initi~ted to ensure filter pap~r tension was maintained. The channel was returned to service*on March 31, 19~2 following successful completion of a channel check.

On March 31, 1992, at 1745 hours0.0202 days <br />0.485 hours <br />0.00289 weeks <br />6.639725e-4 months <br />, a CP/P-V*R System isolation signal actuated from the RMS Plant Vent Noble.Gas Monitor, 2R41C. The 2R41C RMS ch~nnel was declared inoperable due to the signal actuation.

Since the 2R12A RMS channel was also inoperable at the. time, Technical Specification 3.3.3.9 Action 34 was entered. At the time of this signal actuation the Au'xiliary Building Ventilation System (ABV) {VF}

I supply and exhaust fans were being swapped.

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*~-- *-*~---- LICENSEE EVENT REPORT (LER) TEXT CONTINUATION .

Salem G~nerating Station DOCKET NUMBER LER NUMBER PAGE u__n_i~*_t_2_ _~_**_ _ _ _ _ _ _ _ _ _ _50_Q_Q_31=.!,_ _ _ . ___~-~-=-_Q_Q_6-_Q~Q ____ 3- -of

• - - - - '

DESCRIPTION OF OCCURRENCE: (cont'd)

On April. 1, 19.92, at 1643 hours0.019 days <br />0.456 hours <br />0.00272 weeks <br />6.251615e-4 months <br />, a CP/P-VR System isolation signal was again actua-"ted off the 2R11A RMS channel. Again this occurred concurrently with a 2Rl1A RMS channel filter tear alarm. Technical Specification Table 3.3-6 and 3.4.7.1 Action Statements w~re entered.

The Nuclear Regulatory Commission was notified of these three (3) ESF actuations in accordance with Code of Federal Regulations lOCFR 50.72(b) (2) (ii) on March 29, 1992 ai liOS hou~s, on March ~1, 1992 at 1841 hours0.0213 days <br />0.511 hours <br />0.00304 weeks <br />7.005005e-4 months <br /> and on April 1, 1992 at 1813.hours.

Technical Specification Tab~e 3.3-6 Action 24 states:

"With the number of channels OPERABLE less than required by the Minimum Channels OPERABLE requirement, comply with the ACTION requirements of Specification 3.4.7.1".

Technical Specification 3.4.7.1 states:

"The following Reactor Coolant Syste~ lea~age detection systems .

shall be. OPERABLE:

a. The containment atmosphere particulate radioactivity.*

monitoring system, '

b. The containment sump level moni~oring system, and

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

Technical Specification 3.4.7.1 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 S~ANDBY 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.".

Techni~al Specification 3.3.3.9 Action 34.states:

With the number of channels QPERABLE less.than required by the Minimum Channels OPERABLE requirement, immediately suspend PURGING of radioactive effluents via this pathway."-

The root cause of the three (3) ESF actuation signal ~vents is attributed to design .

. During the recent Unit 2 refueling* outage. ( 2R6) , several RMS channels

r-

,.

• LICENSEE EVENT REPORT (LER) TEXT CONTINUATION Salem Generating Station ,DOCKET NUMBER LER NUMBER PAGE u~=n=i~t-=2'------------------=5000311~_ --~-~-~O_Q_6-Q_Q_:__ _____ 4 o_L5_ _

APPARENT CAUSE OF OCCURRENCE: (cont'd)

. . .

were upgrad~d via replacement ot their electronics with state of the art equipment (reference design change package 2EC~3086). Included in this design change was the tying together of downscale alarms (e.g.*,

"low flow alarm" on the 2R41C and "paper tear alarm" on the 2R11A) with the CP/P-VR System isolation signal circuitry. Subsequent engineering assessment has shown that actuation of CP/P-VR System isolation on these downscale failures is not necessary; therefore, those failure alarms_ which were tied to the CP/P-VR System isolation circuit as a result of DCP 2EC~3086 have been returned to original design (i.e., alarm only).

Investigation of the 2R11A events revealed that. the filter paper take.,..up motor did not maintain adequate tension on the ,filter paper to ensure it would not loosen and subsequently jam/bind. The filter_

paper take-up motor was replaced. Also, the 2R11A sample box was cleaned and all moving parts lubricated.

Investigation of the 2R41C event revealed that system flow had decreased to the alarm setpoint as a iesult of concurrent wprk. As stated previously, the ABV System fans were being swapped. Also, Chemistry had disconnected the downstream connection to the_ Plant Vent composite iodine and particulate sample pump (in support of 2R45 RMS Channel functional testing), which pulls its sample from the 2R41-sample line and returns it back to the 2R41 sample line. The combination 6f ihese two (2) evolutions resulted in the 2R41 sample flow decreasing to the ~10~ flow alarm" setpoint.

Testing showed that Plant_ Vent flow fluctuates when the ABV System supply and exhaust fans are swapped; however, by itself, swapping of the fans did not cause a drop in flow to the *2R41 alarm setpoint.

With the Composite Sample Pump line disconnected, some ABV System configuration changes would momentarily cause a sufficient decrease in the 2R41 sample pump flow rate to the alarm setpoint.

ANALYSIS OF OCCURRENCE :

• CP/P-VR System Isolation mitigates the release of rad~oactive material to the environment after a design basis accident. Several RMS cheynnels, including the 2R11A and 2R41C channels, aie designed to initiate a CP/P-VR System isolation signal on high activity.

The 2R11A RMS channel monitors the radioactive particulate _content of

• the Containment atmosphere. The channel i~ used in Modes 1 through 4 to identify Reactor Coolant System (ABI leakage in conjunction with the containment sump level monitor_ing system, the containment fan cooler co~densate flow rate monitors, and the, containment radioactive noble gas (2R12A) RMS.

• In Mode 6, the 2R11A chann~l provides indi~ation of a fuel handling accident and early isolation of the Containment in the event of an accident.

The 2R41C channel moriitors Plant Vent ef flµent releases for ' !

• Salem Generating Station

-* .*DOCKET NUMBER

• LICENSEE EVENT REPORT (LER) TEXT CONTINUATION LER NUMBER PAGE Unit 2 5000311 92-006 - - - - * -of

- - -

ANALYSIS OF OCCURRENCE: (cont'd) radioactive noble gasses~ The 2R41C CP/P-VR Syste~ isolation function, is-redundant to the 2R12A channel. In addition to CP/P-VR' System isolation function, the 2R41C channel .isolates the 2WG-41 valve (Waste Gas Decay Tank Vent Control Valve).

The CP/P-VR System.isolation signals were not the result of a release

• of plant vent high activity.- During thes_e events, the CP/P-VR System valves were closed and did not change position. Therefore, these.

events did not affect the health or safety of the public. However, due t6 the automatic a6tu~tion of an ESF sys~em, these events are i:-eportable in accordance with Code of Federal Regulations lOCFR SO. 73 (a) (2) (iv).

CORRECTIVE ACTION:

The CP/P-VRS System isolation signals which were added to downscale failure alarm~ via DCP 2EC-3086 have been removed. The downscale failure alarms reioain active;' although, independent of the CP/P-VR

~ystem isolation signal circuitry.

The 2RllA RMS channel filter paper motor was replaced. Upon successful completion of a channel check, the channel was returned to service and the associated Technical Specifications wer~ exited on April 4, 1992, at 0505 hours0.00584 days <br />0.14 hours <br />8.349868e-4 weeks <br />1.921525e-4 months <br />.

• After determination of the cause of the 2R41C ESF signal actuation, on M~rch 31, 1992 at*2202 hours, Technical Specification 3.3.3.9 Action 34 was exited.

General Manager -

Salem Operations MJP:pc SORC Mtg.92-051