ML20043A227

LER 90-006-00:on 900414,auxiliary Bldg Isolation Occurred from Spent Fuel Pit Area Radiation Monitors 0-RM-90-102 & 103.Caused by Personnel Error.Training Ltr Issued to Instrument Mechanics & Operations personnel.W/900514 Ltr

ML20043A227
Person / Time
Site:	Sequoyah
Issue date:	05/14/1990
From:	Bynum J, Spencer S TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
LER-90-006-01, NUDOCS 9005210035
Download: ML20043A227 (4)

Text

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TENNESSEEi VALLEYR AUTHORITY 6N 38A Lookout Place ~

Chattanooga . Tennessee 37402-2801:'

May114,o1990

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i U.S. Nuclear. Regulatory Commissioni

. ATTN Document Control' Desk, ,

Washington, D.C.; 20555. ,.

Gentlemen -

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.. TENNESSEE VALLEY AUTHORITY -.'SEQUOYAH NUCLEAR PLANT UNIT 1 - DOCKET N0i

50-327 - FACILITY OPERATING LICENSE;DPR LICENSEE EVENT REPORT (LER); '

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327/90006 ,

-The:enclos'ed LER'provides details.concerning an inadvertent: auxiliary; building ,

isolation- that occurred because. a radiation monitor -relay was not

reset 'af f er.  ;

'the performance of.a postmaintenance test. This event is reported.in'

'accordance with 10 CFR 50.73(a)(2)(iv)l.as- an engineered' safety: feature actuation.-

-Very truly yours.

~

' TENNESSEE VALLEY AUTHORITY?

J.' R. B . Vice President

' Nuclear Power ProductionL -[

f Enclosure ,

7 cc (Enclosure):

• INPO Records 1 Center Institute of Nuclear Power Operations 1100 circle 75 Parkway, Suite'1500 Atlanta, Georgia 30339:-

1 NRC Resident Inspector l Sequoyah Nuclear Plant 2600.Igou Ferry Road .

Soddy Daisy. Tennessee 37379 :t Regional Administration I-U.S. Nuclear ~ Regulatory Commission

, Office of Inspection and Enforcement Region II 101 Marietta Street, Suite 2900 Atlanta. Georgia 30323 ,

t 9005210035 900514 P PDR ADOCK 05000327 --

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F ACILITV NAME 11) DOCKET NUMSER 12) PAGE I3i S2quoyah Nuclear Plant. Unit 1 01510 l o l 013 l 2 l 7 1 lOFl0 13 ,

'"An inadvertant auxiliary building isolation occurred when maintenance personnel failed to comflete required steps of the postn.aintenance test EVENT DATE ISI LER NUMBER tel kEPORY DATE (7) OTHER F ACILITIES INVOLVf D (Si 8 ACittiv ee AMas 00CKE1 NUMSER(5p MONTH DAY YEAR YEAR "O L"' "*j,$

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NAME TELEPHONE NUMSER AREA CODE S. W. Spencer, Compliance Licensing Engineer 6l1l5 84 3 -l7l5l 4l0 COMPLETE ONE LINE FOR E ACH COMPONENT F AI URE DESCRISED IN TH18 REPORT (131

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On April 14, 1990, at 1759 Eastern daylight time, with Unit 1 in Mode 6 and Unit 2 in Mode 1 an auxiliary building isolation (ABI) occurred. The ABI signal was initiated from the spent fuel pit area radiation monitors (RMs) 0-RM-90-102 and 103 during l rcstoration of the RMs. The RM's high radiation relays had been removed to prevent i inadvertent actuation and facilitate the transfer of highly contaminated piping from the

. containment building to the refueling floor for decontamination. .After completion of the postmaintenance test on RMs 0-RM-90-102 and 103, the handswitches for 0-RM-90-102 and 103 were not reset before unblocking the RMs resulting in the ABI. Immediate corrective action consisted of recovery and resetting of the ABI and initiating the avsnt investigation. Corrective action consisted of issuing a training letter to instrument mechanics and Operations personnel, taking appropriate disciplinary actions for personnel involved, and holding lessons learned meetings with planners to enhance specifically addressing engineered safety feature functions.

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~Dascription of Event t

On April 14, 1990,'at 1759 Eastern daylight time (EDT) with Unit 1 in Mode 6-(shut down for refueling) and Unit 2 in Mode 1 (100 percent power 2,235 pounds per square' inch ,

g,uge, and 578 degrees Fahrenheit) an auxiliary building isolation (ABI) (EIIS Code VF) occurred. .

s On April 13, 1990, in accordance with Work Request-(WR) 773130, Maintenance removed the hjgh radiation relays from spent fue", pool area Radiation Monitors (RMs) (EIIS Code IL)~

0-RM-90-102 and 0-RM-90-103 to prevent inadvertent actuation-and facilitate the transfer of highly contaminated piping from the containment building to the refueling floor for dscontamination. The WR had required checkoffs for the postmaintenance test (PMT) and the work described required no qualification factor other than basic journeyman skills.

On April 14, 1990, the refueling supervisor requested that the relays be reinstalled to allow the use of the auxiliary building crane above the spent fuel pool'to remove inspection equipment. ' Steps 3 and 6 of the WR required the resetting of control room Hindswitches 0-HS-90-102'and 0-HS-90-103 located on Panel 0-M-12. These two hindswitches are interlock reset switches, which deenergize Relays NR102 and NR103. The high radiation' relays were installed, and.the PMT was started. The instrument mechanics (IMs) verified that the RMs 0-RM-90-102 and 103 were blocked simulated a high radiation signal and verified the appropriate annunciators illuminated. The: annunciator alarms-ware' cleared, however, the IMs did not realize that.the handswitches were interlocked; therefore, concluded that resetting the handswitches as required by Steps 3 and 6 of the WR was not necessary because the annunciator alarm had cleared. The IMs informed the i unit operator that the PMT was complete, and the RM could be unblocked. Even.though the RM signal blocking handswitches have an operator aid requiring the resetting of Handswitches 0-HS-90-102 and 103, respectively,:the operator failed to reset the i switches. Upon unblocking of the RMs, a path was provided for initiation of the ABI.

Operations immediately verified that the ABI was inadvertent and reset.the ABI in -

accordance with System Operating Instruction (SOI) 30.5D, " Recovery from Auxiliary  !

Building Isolation," and returned the RM to service ten minutes'after the event at 1809 EDT.

Cruse of the Event

Ths root cause of this event was attributable to personnel error by the IMs in that the-IMs did not follow the steps as detailed in the WR. A contributing factor was failure of the operator to follow the operator aid by unblocking the RMs before resetting 0-HS-90-102 or 103.

I Annlysis of Event An ABI is an engineered safety feacture (ESF) actuation and is reportable pursuant to i thn criteria established in 10 CFR 50.73(a)(2)(iv). '

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TEXT f# more masse e soeuseet oss salisummer NAC perm m W (171 Analysis of Event (Continued)

An ABI-can be automatically initiated by either: (1) high temperature'in the auxiliary l building air intake (2) high radiation in the spent fuel pool-area .(3) Phase _A-containment isolation signal..or (4) high radiation in the auxiliary building vent. ,

During this event, a high radiation signal was simulated.on the RM for the spent-fuel' pool and, an- ABI was generated. Subsequent to. the ABI signal, all equipnient functioned j

-as designed as the' general supply and exhaust. fans shut off, the fuel handling-area fans shut off, the appropriate dampers operated, and both. trains of auxiliary building' gas- l treatment system started. Because no high radiation levels actually existed, this did-  ;

not adversely effect the health and safety of the public. i Corrective Actions'

'As immediate corrective action, Operations personnsi recovered from the ABI in cecordance with SOI-30.50.

Corrective action to prevent recurrence include the following:

1. Appropriate disciplinary action was taken for Operations and-IM personnel involved l in this event.

l l 2. Lessons learned: meetings were conducted with WR planners to ensure personnel r understand the importance of identifying ESF actuation steps separately.

3. A training letter was issued to Operations personnel addressing the specific operator aid concerninF this event and addressing operator aids in general. ,

Additional Information There have'been three previously reported occurrences-of inadvertent'ESF actuations from .,

similar activities. The previous events are SQRO-50-327/88030, 50-327/88038, and 50-328/88035. The previous actuations resulted from inadequate PMTs, not from failure to follow the steps identified in the PMT.

Commitments None.

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. NRC Form SEBA (M95  ;