05000213/LER-1996-001, :on 960111,determined That High Side Sensing Line of Instrument Blocked.Caused by Blocked Sensing Line & Personnel Failure to Immediately Identify Problem W/Gauge. Personnel Counseled
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- 4 CAR Fan Surveillance Invalid Due To I' lugged instrument Tap EVENT DATE 16)
LER NUMaER 16)
REPORT DATE 17)
OTHER FACILITIES INVOLVED (S) l MONTH DAY YEAH YEAR
$LOVENrlAL REVISION MONTH DAY YEAR f ACIUTV NAMt DoCe t1 NVMDlM l
NUMBER g3090 l
01 1l 96 96 001 01 08 01 97
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OPERATINO THIS REPORT IS SUSMITTED PUR$UANT TO THE REQUIREMENTS OF 10 Cf R l ICheCk one of more) (III ODE (M i
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20.2203(aH2Hivl 60.3bicH2) 60.73(aH2Hvid LICENSEE CONTACT FOR THIS LER(12)
NAME TELtPHONE #dVMDLR tificlude Aeta Cocal G. P. van Noordennen (860)267 3938 COMPLETE ONE LINGT6hTK5RT6W5NDiTTATWNE DESClll8ED IN THIS REPORT 113)
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EXPECTED MONTH DAY VLAR SUSMISSION YES
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(if Yes, complete EXPECTED SUBMISSION DATEL ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
(16)
On January 11,1996, at 1000 hours0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br />, with the plant in Mode I at 100 percent power, w hile checking the No. 4 Containment Air Recirculation (CAR) Fan cooling coil differential pressure gage, it w as determined that the high side sensing line of the instrument was blocked. A review of past data indicated the instrument may have been reading incorrectly since August,1995, Without accurate instrumentation the Technical Specification surveillance requirement could not have been met. The cause of the event has been attributed to a blocked sensing line and personnel failure to immediately identify a problem with the gage. The immediate corrective action was to unplug the sensing line and perform the surveillance. The surveillance was performed with satisfactory results u hlch indicated that the No. 4 CAR Fan was operable since August 1995, Personnel were counseled on the importance of noting abnormal changes in sutteillance data and bringing this to the attention of management. This event is reportable under 10CFR50.73(aX2)(iXD) as a condition prohibited by the plant's Technical Specincations.
'this supplemental report is being issued to retract originally proposed corrective actions that were scheduled to be implemented during the next refueling outage and are no longer necessary as a result of the lladdam Neck Plant being in a permanently defueled
- state, 9708110121 970001 PDR ADOCK 05000213 S
Nnc FORM 366A U.S. NUCLEAR Rt;UL ATORY COMMis$10N 14 PM UCENSEE EVENT REPORT (LER)
TEXT CONTINUATION f ACILITY NAME tu DOCKET NUMBLR 12) tiR NUMBER I6)
FAGE (3)
YEAR LLOUINilAL RE VISION lladdam Neck WF R M UL 05000213 96 001 01 2 of 3 Text fit more space is requued use edJtronalcopies of NRC form 366Al (11) l IIACKGROUND INI ORM ATION four containment air recirculation (CAR) fans (1:11S Code.IIK) take suction near the outer periphery of the containment building middle level and discharge to a common duct uhich branches to distribution outlets within containment. During nonnal operation air enters the units through " bypass" dampers to cooling coils and then to the fan. These dampers are so named because they bypass the accident mitigation section of the unit (chevron moisturc separators, high etliciency particulate air (Ill:pA) Olters, and ch:rcoal adsorbent trays). Under normal conditions the inlet to the accident section is blocked by the " face" dampers. Upon receipt of a rafety injection / high containment pressure signal, the " face" dampers open and the
- bypass" dampers close and air flows through the accident section of the CAR fan unit to the cooling coils to the fan. Technical Specincation 3.6.2 requires four CAR fans operable in Modes I through 4. Technical Specification 4.6.2 requires demonstrating each CAR unit operable at least once per 31 days by verifying a heat removal rate of greater than or equal to 26.51:6 lituhr at 261 degrees F containment conditions. 'this Technical Speci0 cation is met by verification of acceptable cooler hydraulic resistance on the raw water side.
EVENT DI:SCRipTION On January 11.1996, at 1000 hours0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br />, with the plant in Mode I at 100 percent power, while checking the No.4 Containment Air Recirculation (CAR) cooling coil difTerential pressure gage, it was determined that the high side sensing line of the instrument was completely blocked. A review of past No.4 CAR Fan Cooling coil suncillance results indicated the instrument may have been reading incorrectly since August 1995. There was a signl0 cant decrease in the hydraulic resistance surveillance results in August 1995 that was not noticed. In December 1995, a problem with the dif ferential pressure page was suspected. Upon investigation on January 11,1996, it was con 0rmed that the high side sensing line of the instrument uas blocked. Without accurate No.4 CAR coil differential pressure, the Technical Specincation sun cillance requirement uas not being met and, therefore, the operability of the No.4 CAR fan w as not being verined. This event w as considered a missed surveillance.
CAUSE OF Tile EVENT The cause of this es ent has been attributed to blockage of the CAR cooling coil differential pressure instrument line and personnei failure to identify an abnormal trend in a timely manner. The surveillance results were within the acceptance criteria of the procedure during the period. the acceptance criteria includes an upper limit but no lower limit. There were no speclR:
instructions to verify that the data was not tiending in a direction indicating the cooling coils were getting cleaner, Et,yhasis was placed on ensuring the data was not trending suct that a failure of the sunci!!ance acceptance criteria haJ or M occur. The abnormal data w as not recognized immediately by personnel involved in testing and trending.
l The blocked instrument line was caused by sitt in the service water which fouled the nipple upstream of the mstrument root isolation vahe. Over time this fouling caused partial blocking of the instrument sensing line, it appears that when the instrument was inspected and an attempt was made to flush the sensing line, complete blockage of the line occurred.
SAFETY ASSESSMENT
This esent is reportable under 10CFR50.73(aX2XI)(B) as operation or a condition prohibited by the plant's Technical Speci0 cations. A review of past data indicated the instrument may hase been readmg incorrectly since August,1995. Without accurate instrumentation the Technical Specification suncillance requirement could not have been met.
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NitC f OHM 366A U.S. (;UCLt.AR FtE;ULATORY COMMISSION 14 c6)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION f ACtllTV NAME til DOCKET NUMBER 12)
Lt R NUMBf R 16)
PAOf 13)
YEAR S(OUt N11AL HE VISION lladdam Nc(k NUMRtR NUMEl.!L 05000213 96 001 01 3 of 3 1LK1 It!Inore space is requard use ad&tionalcopies of NRC form 366Al 11Tt Technical Specincation 4.6.2 requires demonstrating cath CAlt unit operable at least once per 31 day s by verifying a heat removal rate of greater than or equal to 26.51:6 Intu hr at 261 degrees F containment conditiont 1he heat removal requirement is verined by the measurement of the hydraulic resistance of the senice water through the cooler whlch is used as the cooling medium.1he blockage of the high side sensing line of the pressure instrumentation resulted in the indication of a lower cooler differential pressure than the previous surveillance test. This implied that the cooler portion of the CAR fan was cleaner than previous indications.1he surveillance procedure was performed after cleaning of the sensing line and the heat removal capability was demonstrated to be acceptable in accordance with the Technical Speci0 cation requirement.
Since the CAlt fan was operable and capable of perfunning its intended function during the period in question the safety signincance of this esent is low.
CORiti:CTIVE ACTIONS Immediate corrective action was to unplug the high side sensing line and perfonn the surveillance. The surveillance was performed with satisfactory results which would indicate that the No.4 Call l'an was operable since August 1995. Personnel were counseled on the importance of noting abnonnal changes in surveillance data and bringing this to the attention of management.
Also, the surveillance procedure was revised and data acquisition personnel will review previous trend data prior to performing the surveillance. The procedure also includes, in the evaluation process, guidance to look for and investigate any signincant changes in the data.
ADDillONAL INI Olth1ATION Ihis supplemental report is being issued to retract originally proposed correctise actior 'cheduled for implementation in the nest refueling outage that will no longer be necessary as a result of the lladdarn Neck Plant being in a permanently defueled state.1hese long tenu corrective actions included ievising the sun eillance procedure to Oag and imestigate abnonnal changes in results. In addition, procedures would bas e been revised to incorporate the steps necessary to inspect / clean the sensing lines, gages, and calibrate th-ages on line, PitEVIOUS SthilLAll EVENTS None.
IGC FORM 3f>6A 14 95)