ML20059D146
| ML20059D146 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 08/21/1993 |
| From: | AFFILIATION NOT ASSIGNED |
| To: | |
| References | |
| OLA-2-I-MFP-150, NUDOCS 9401070032 | |
| Download: ML20059D146 (13) | |
Text
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MANAGEMENT
SUMMARY
l While performing design modifications in radiation monitor cabinet RNRMA per work order C0072962, a craftsperson was bending a smoke detector brace. During removal of the channel lock pliers from the cabinet, the pliers came in contact with the terminals on fuse block RM-5, thus causing l a voltage transient and a containment ventilation isolation (CVI) signal (ref. 4 through ref. 8).
The root cause was determined to be personnel error in that if the electrician had taped the tool, contact with the fuse block may not have occurred.
To prevent recurrence of this event, all previous maintenance bulletins not distributed to GC will be distributed, tailboard meetings will be held with all GC crews to review previous maintenance bulletins relevant to this event, and the GC training matrix will be revis'ed to assure that all maintenance bulletins will be included.
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NCR DC1-90-WP-N093 f January.18, 1991- ,
NCR DC1-90-WP-N093 INADVERTENT GROUND:CAUSES CVI i
I. Plant Conditions .
Unit 1 was in Mode 3 (Hot' Standby) at 0% power-(ref. ,
8).
II. Description of-Event A. Event: '
While performing design modifications-in radiation monitor cabinet RNRMA in the' control room per work' '
order C0072962,. a craftsperson was' bending a smoke.
detector brace.: .Two other similar jobs had previously been successfully completed. .~.During.
removal of the channel lock pliers from.the.
cabinet, the pliers came in' contact with the.
terminals.on the fuse block for RM-5, thusicausing a voltage transient on inverterJIY-11A.- The :
transient spiked RM-111and'RM-12, ' causing a containment ventilation' -isolation o (CVI).' signal.
Containment isolation valves-FCV-681:and'691' l closed (ref. 4 through ref. 8).
CVI is an engineered safety feature ~(ESP), so;the inadvertent actuation is reportabic'to.the NRC in accordance with 10. CFR 50.72 (b).(2) (ii)L and 50.73 (a) (2) (iv) .
B. Inoperable Structures, Components, or Systems that-Contributed'to the Event:
None.
C. Dates and Approximate Times for Major Occurrences.
- 1. Dec. 27, 1990; 14:31'PST:
Event / Discovery-
.date. Inadvertent, ground causes CVI
'(ref.'4 through-ref. 8).
- 2. Dec. 27, 1990; 15:18 PST: The 4-hour non-emergency.
report required by; 90NCRWP\90WPN093.PSN Page 2 of 13'
at .
NCR DC1-90-WP-N093 January 18, 1991' 10 CFR 50.72 (b) (2) (ii) ,
was'made (ref. 6).
D. Other Systems or Secondary Functions Affected:.
None.
E. Method of. Discovery:
The event was immediately-apparent to plant operators due to alarms and indications received in the control room (ref. 4).
F. Operators Actions:
Alarms were reset and CVI was restnred to.normall (ref. 4.and ref. 6 through ref. 8).
G. Safety System Responses:
Containment isolation valves FCV-681 and 691 closed (ref. 8). As discussed in the'TRG, other ~
-valves that are designed to close upon CVI were-already closed.
III. Cause of the Event A. Immediate Cause:
Voltage transient on RM-11 and RM-12 caused.
closure of containment 11 solation valves FCV-681 ;
and 691-(ref. 8) 1 B. Determination of Cause-l
! 1. Human Factors: i l 1
- a. Communications: Not a factor. Personnel were aware that panel was hot and caution was- l needed..
- b. Procedures: Not a factor. The TRG l discussed and docided that procedural guidance was adequate. -The work order-I adequately emphasized that 1
90NCRWP\90WPN093.PSN Page 3l oof 13 j l
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l NCR DCl-90-WP-N093 l January 18, 1991 I
panel was hot, maintenance bulletins and tailboards provide adequate guidance, and no formal procedure is needed-for working on energized equipment.
l c. Training: Not a factor. Electrician was j adequately trained and had 35 years of experience.
l
- d. Human Factors:- Work order and tailboard did adequately emphasize to personnel that the panel was hot.
- Inadequate tool? No. The TRG interviewed the electrician and the large pliers was deemed necessary at the time.
- Should smoke detector have been removed and bracket have been modified in shop? No - the method of' work was adequate.
Removing the bracket was a greater risk than performing the work with it in place.
- Should we have: adjusted from the front of panel?
No - work easier to do from back.
- The TRG considered permanent barriers on the fuse block, but determined they were not necessary because no routine tasks are performed in the cabinet.
- As discussed in the TRG, temporary taping of the
{ fuse block was infeasible because it is fragile.
- e. Management System: Should we have had a clearance? No - a clearance on the j 90NCRWP\90WPN093.PSN Page 4 of 13
l
. i NCR DC1-90-WP-N093 f January 18, 1991 entire cabinet would not be feasible, i
However, Maintenance l
l Bulletin #007 which j addresses working on l l
l energized equipment l had not been distributed to GC.
- 2. Equipment / Material: N/A. This event was not caused by a material or equipment failure. l
! a. Material Degradation: N/A.
- b. Design: N/A.
- c. Installation: N/A.
- d. Manufacturing: N/A.
- e. Preventive Maintenance: N/A.
- f. Testing: N/A.
- g. End-of-life failure: N/A.
C. Root Cause:
The root cause was determined to be personnel error in that if the electrician had taped the tool, contact with the fuse block may not have occurred. l l
D. Contributory Cause: )
1 If maintenance bulletin #007 had been reviewed l with the electrician, it may have prompted him to l tape the tool.
IV. Analysis of the Event A. Safety Analysis:
The voltage transient on the inverter resulted in a CVI actuation. This actuation is conservative, regardless of plant conditions. If an actual emergency had occurred during the event, the l 90NCRWP\90WPN093.PSN Page 5 of 13
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NCR DC1-90-WP-N093 January _18, 1991 l
ventilation systems would have been ready to perform their accident prevention functions.
Therefore, the health and safety of the public was not adversely affected.
B. Reportability:
- 1. Reviewed under QAP-15.B and determined to be non-conforming in accordance with section 2.1.2 as a significant non-routine event that requires' reporting to the NRC.
- 2. Reviewed under 10 CFR 50.72 and 10 CFR 50.73 ,
per NUREG 1022 and determined to be reportable in accordance with 10 CFR 50.72 (b) (2) (ii) and 50.73 (a) (2) (iv) .
- 3. This problem does not require a 10 CFR 21 report.
- 4. This problem does not require reporting via an INPO Nuclear Network entry.
- 5. Reviewed 10 CFR 50.9 and determined event was not reportable under 10 CFR 50.9 since event was being reported under 10 CFR 50.73.
V. Corrective Actions A. Immediate Corrective Actions:
i All work was stopped for investigation. Verified no blown fuses, containment ventilation isolation was reset, and FCV-681 and 691 were reopened. STP l I-100A was performed on RM-11 and RM-12 to verify l operability (ref. 4 and ref. 6 through ref. 8).
B.
Corrective Actions to Prevent Recurrence:
1.
Determine I&C and Electrical / Mechanical maintenance bulletins that have not been distributed to GC. Distribute them to GC, and determine which bulletins are relevant to this event.
RESPONSIBILITY: F. Krall ECD: COMPLETE DEPARTMENT: Construction Coordination Tracking AR: A0212650 , AE #05 90NCRWP\90WPN093.PSN Page 6 of 13
i NCR DC1-90-WP-N093 January 18, 1991 i
1 Outage Related? No JCO Related? No NRC Commitment? Yes CMD Commitment? No
- 2. Tailboard GC. Electrical and I&C crews to i review.those bulletins relevant to-this event.
RESPONSIBILITY: I. Zakaria ~ ' ECD: 1/31/91 -
DEPARTMENT: GC Electrical Tracking AR: A0212650 , AE #06' .i Outage Related? No :
JCO Related? No :
NRC Commitment? Yes CMD Commitment? No (
- 3. Revi_e the GC training matrix to assure that maintenance bulletins will.be included.
-s RESPONSIBILITY: F. .Krall~ ECD: 3/1/91 ;
DEPARTMENT: Construction Coordination .
Tracking AR: A0212650 , AE#07 j outage Related? No l JCO Related?- No NRC Commitment? Yes !
CMD Commitment? Yes 4
VI. Additional Information A. Failed Components: ,
None. j B. Previous Similar Events:
- 1. NCR DC2-86-TI-N041 and LER 2-86-010-00: This and other previous CVI actuations were .
determined to'have been caused by electrical noise. Therefore, corrective actions to prevent recurrence could not have prevented the recent event.
- 2. NCR DC1-87-TI-N120 andELER 1-87-021-00: The root cause of~this CVI actuation was:
determined to be. personnel error by I&C ;
j personnel. The corrective ~ actions to' prevent-
. recurrence were' training focused-on the I&C ;
department and did not prevent the.recent-90NCRWP\90WPN093.PSN Page 7 of 13 .
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. 1 a \
NCR DC1-90-WP-N093 January lo, 1991-event, which was caused by GC' Electrical personnel. H
- 3. NCR DC1-88-ST-N012 and LER- 1-88-007-00: The' I root cause of this CVI actuation was that quality checks were not performed as required by procedures. -Corrective actions. focused;on' i assuring' completion of quality checks prior to re-energizing electrical circuits. Since the -
t recent event occurred during work on energized- -l circuits, the corrective actions did not- '
prevent the recent. event. I Tb .
I
- 4. NCR DCl-89-TI-N027 and LER 1-89-001-00: The-root cause of this CVI actuation.was !
determined to be personnel error by I&C .
{
personnel. .The corrective actions to prevent- J recurrence were training. focused on the I&C l department"and establishment of an I&C departmentLpolicy.to de-energize equipment {
i whenever possible'before working on'it. The ;
corrective actions could not'havesprevented' !
the recent event,.as the cabinet could not 1 feasibly be taken out of service for the work. !
! 5. NCR DC1-89-TI-N097 and~LER- 1-89-011-00:' The j root cause of this CVI actuation was '
determined to be personnel error.by I&C personnel. The corrective actions included a maintenance bulletin on cautions when.workingL on energized equipment. However, maintenance i
' bulletins were not being distributed;to GC at-the time this bulletin was issued:so the l l
corrective action.did not preventithe recent. !
event.
- 6. NCR DC2-90-TI-N025'and LER 2-90-004-00: The !
root cause of this CVI was determined to be '
personnel error by I&C personnel during troubleshooting. ' The corrective actions included training of'I&C personnel 1and a design evaluation of terminal. strips in Gammametrics cabinets. The corrective actions did not prevent the recent event because the.
recent. event was caused by'GC personnel inadvertently touchingla fuse. block during work on a different.part of the~ cabinet. 1 90NCRWP\90WPN093.PSN Page 8 of' 13 t i
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W NCR DC1-90-WP-N093
! January 18, 1991 C. Operating Experience Review:
- 1. NPRDS:
i Not applicable.
l
- 2. NRC Information Notices, Bulletins, Generic Letters (ref. 9):
l IE Information Notice 83-23: This information l notice was issued to remind all licensees of l the importance of assuring that procedures are l both properly developed and carefully l followed. The NRC staff was of the opinion
! that inadequate surveillance procedures or
! inadequate implementation of the procedures were the underlying cause(s) of the exam-1.es cited. Since the notice and PG&E's response were focused on surveillance procedures, they could not prevent the recent event, which was caused by an inadvertent short not related to surveillance procedures.
l IE Information Notice 81-14: This information notice deals with potential failure of Fisher Series 9200 butterfly valves. This notice is not applicable to the receent event.
IE Circular 81-09: This circular deals with containment effluent water that bypasses radioactivity monitors. It is not appliceble to the recent event.
3.
INPO SOERs and SERs (ref. 9): !
SER 28-81: See IE Information Notice 81-14 above.
D. Trend Code:
RE - A3 (Resident Electrical) -
(Personnel Error, Lack of Mental Attention)
E. Corrective Action Tracking:
- 1. The tracking action request is A0212650.
- 2. Are the corrective actions outage related? No.
90NCRWP\90WPN093.PSN Page 9 of 13 u
d NCR DC1-90-WP-N093
' January 18, 1991:
F. Footnotes and Special Comments:
None.
G.
References:
- 1. Design Change Package DCP-J-43442
- 2. Action Request A0172061 3., Work Order C0072962
- 4. Shift Foreman Log dated 12/27/90
- 5. Personnel Statement from L. Polieridated 12/27/90 g
- 6. Diablo. Canyon Power Plant Event Notification Form dated 12/27/90
- 7. Initiating Action. Request A0212436,
- 8. Information'from Work Planning - F. Krall
- 9. Search'of the OEA database for NRC.Information.
Notices,' Bulletins,-Generic ~ Letters, INPO SOERs and SERs - performed by P.-Natividad H. TRG Meeting Minutes:
On January 2, 1991,-the TRG convened andl considered the following:
Clarification of event sequence -- the ground at-the fuse block for RM-5 caused.a1 voltage transient on the inverter. The transient' caused hi-rad on-RM-11 and 12, which caused CVI (Rudy Ortega to verify - see Investigative Action #4 below).
As discussed in the TRG,'there were no other actuations or significant consequences from the inadvertent ground.
Discussion of root cause ' items discussed included: 1) tools should they have been rubber coated? (Investigative: action assigned'to'~Issa Zakaria. See Investigative Action #2 below); 2).
Work package - adequately emphasized that the 90NCRWP\90WPN093.PSN Page 10 .of' 13
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i NCR DC1-90-WP-N093 January 18, 1991 panel was hot; 3) work environment was adequate, though since the cabinet was'small, a smaller pliers should have been used; 4) tailboard was adequate. The preliminary root cause was determined to be personnel error in that adequate cautions were not exercised during the work on the hot panel. Investigative actions were assigned to verify this root cause (see below).
Corrective actions will be determined after investigative actions are complete and root cause is verified.
The TRG will discuss previous similar events at l
the reconvene.
TRG will reconvene Thursday, 1/10/93 at 10:00.
On January 10, 1991, the TRG reconvened and considered the following:
The TRG interviewed the electrician involved in the event. The electrician stated that the contact occurred on the side of the fuse terminal block opposite him above his pliers while he was avoiding wires in the cabinet. The rest of the cabinet was taped off. With hindsight, the electrician would have used a smaller pliers and worked from the front of the cabinet. The electrician had used a larger pliers and worked from the back of the cabinet because he thought i the bracket would be harder to bend than it i actually was. He stated that if the ra.intenance bulletin (regarding precautions such as taping tools) had been reviewed with him, he would have done so. The TRG determined that if he had taped the tool, the inadvertent contact might have been prevented. The electrician was adequately cautioned and aware that'the cabinet was energized before performing the work. He was not involved !
with the two previous similar jobs that were done. i As discussed in the TRG, taping off the fuse block was infeasible because-it was fragile. Also, there was no way to place the wires out of the way _
because they came from both sides.
90NCRWP\90WPN093.PSN Page 11 of 13
NCR DC1-90-WP-N093 January 10, 1991 There is no plant.or GC procedure specifically regarding work on energized equipment. The TRG determined that none is needed, as precautions against energized equipment are common knowledge to journeyman electricians, and I&C maintenance bulletin 89-12 and Electrical / Mechanical Maintenance Bulletin #007 are adequate to disseminate additional guidance. Maintenance Bulletin #007 provided precautions such as treating all equipment as if it were energized and
- taping tools. However, GC did not start receiving maintenance bulletins until after #007 was issued.
The TRG discussed providing warnings (n) work orders or on the LDC/ sponsor meeting checklist that a potential CVI could result from the work.
However, potential problems from incidental contacts are beyond the scope of the work.
l The TRG discussed the time delays on the radiation monitors. The TRG determined that it is technically reasonable that only RM-11'and 12 would have been affected by the transient.
l The overall ECD for this NCR was determined to be 4/1/91. This TRG will not reconvene.
I. Investigative Actions
- 1. Interview the involved personnel and verify the root cause determined by-the.TRG.
RESPONSIBILITY: I. Zakaria ECD: COMPLETE DEPARTMENT: GC Elect.
l Tracking AR A0212650 , AE #01 Outage Related? No JCO Related? No NRC Commitment? No CMD Commitment? No
- 2. Review current NECS policy on working on energized equipment. Investigate whether it l is the same as plant policies, and whether it i
needs revision or enhancement.
RESPONSIBILITY: I. Zakaria ECD: COMPLETE DEPARTMENT: GC Elect.
Tracking AR A0212650 , AE #02 90NCRWP\90WPN093.PSN Page 12 of 13 l
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NCR DC1-90-WP-N093 January 18, 1991 Outage Related? No JCO Related? No
-NRC Commitment? No CMD Commitment? No ,
-l
- 3. Review the adequacy of'the LDC/ Sponsor meeting {
checklist. Review should include:the :
determ/reterm checkoff and. feasibility of an l additional " potential ESF actuation" checkoff.
RESPONSIBILITY:- F..Krall -ECD: COMPLETE DEPARTMENT: Construction Coordination.
Tracking AR A0212650 ,. AE #03 Outage Related? No JCO Related? No NRC Commitment? No CMD Commitment? No
- 4. Verify the CVI actuation signals occurred as postulated in the TRG. Verify that a clearance on the entire radiation monitor cabinet for work is not-feasible.
RESPONSIBILITY: R. Ortega ECD: COMPLETE DEPARTMENT: System' Engineering; Tracking AR A0212650 , -- AE~#04 Outage Related? No ,
JCO Related? No NRC Commitment? No >
CMD Commitment? No ,
- 5. Investigate the availability of non-conductive type tools.
RESPONSIBILITY: I. Zakaria ECD:- COMPLETE ,
DEPARTMENT: GC Elect.
Tracking AR A0212650 , 'AE #08 Outage Related? No JCO Related? No '
NRC Commitment? No CMD Commitment? No 90NCRWP\90WPN093.PSN Page 13 of. 13-
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