ML20062J983
| ML20062J983 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 08/18/1993 |
| From: | AFFILIATION NOT ASSIGNED |
| To: | |
| References | |
| OLA-2-I-MFP-053, OLA-2-I-MFP-53, NUDOCS 9311190409 | |
| Download: ML20062J983 (18) | |
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a DC2-93-MM-N013 UNIT 2 CONTAINMENT EQUIPMENT HATCH NOT FULLY CLOSED DURING CORE OFF-LOAD MANAGEMENT
SUMMARY
On March 12, 1993, at 1416 PST, the Refueling SRO reported observing the Unit 2' equipment hatch had a visible, approximately 1/2 inch gap in the upper 25% of its seal.
Core offload had been in progress and was immediately suspended.
On March 12, 1993, at 1615 PST, the Operations shift supervisor completed a four-hour, non-emergency notification of the NRC in accordance with 10 CFR 50.72 (b) (2) (iii) (C).
This event requires a 30-day written report to the NRC, due by April 12, 1993, in accordance with 10 CFR 50.73 (a) (2) (v) (C).
This draft dated May 28, 1993, contains the minutes from the TRG l
1 meeting held on May 28, 1993.
The TRG decided not to reconvene.
This NCR will be circulated to the TRG members for comments.
The members are to submit their comments to the TRG secretary by June 8,
1993.
The NCR will be signed and submitted'to the PSRC for-review and subsequently to QA for closure.
TRG CLOSURE ECD:
09/30/93.
9311190409 930818 PDR ADOCK 05000275 0
PDR 93NCRWP\\93MMN013.PGL Page 1
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o l i
NCR DC2-93-MM-N013 00 l
May 28, 1993 3.
March 12, 1993, at 1416 PST:
Discovery date.
Refueling SRO j
reported observing i
the Unit 2 equipment hatch-had a visible, i
l approximately 1/2 inch gap in upper portion of its seal.
Core offload was immediately 1
- suspended.
4.
March 12, 1993, at 1430 PST:
Mechanical Maintenance made-up and torqued an additional eight hr:ch bolts when informed of the equipment hatch condition.
A.
- verification that there was no visible gap at the hatch
- sealing' surface as-l viewed from outside l
the containment was performed.
4.
March 12, 1991, at 1635 PST:
Operations shift supervisor completed
- a four-hour, non-emergency not??ication,of the NRC in accordance with 10 CFR-50.72 (b) (2) (iii) (C).
F.
Other Systems or Secondary Functions Affected:
None.
L G.
Method of Discovery:
Utility personnel, during performance of a normal shift.
i equipment observation tour identified the problem.
H.
Operator Actions:
Core offload was immediately suspended.
93NCRWP\\93MMN013.PGD Page 4'
of 18 I
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l NCR DC2-93-MM-N013 00 May 28, 1993 l
I.
Safety System Responses:
i i
None required.
III.
Cause of the Event A.
Immediate Cause:
f Inadequate closure t. ~ the containment equipment hatch.
B.
Determination of Cause:
1.
Human Factors:
a.
Communications:
1 I
There was an inadequate tailboard by Mechanical l
Maintenance personnel prior to the equipment hatch closure attempt.
Visual verification that there was no gap at the hatch sealing surface from Qutside of containment was not discussed.
b.
Procedures:
The maintenance procedure (ref. 6) was adequate for the hatch closure activity had personnel followed it.
The procedure will be enhanced (as a prudent action) to make it easier to comply
- with, c.
Training:
N/A.
d.
Human Factors:
A potential contributing cause for this event.
Schedule pressures and difficult' access to the upper hatch bolting could have influenced personnel actions during this event.
Investigative action V.B.4.
requests a human factors review for this. event, e.
Management System:
There was no independent QC verification of the equipment hatch closure required during this event, whereas there is QC verification for other equipment hatch closure activities.
Investigative action V.B.5. will document this potential contributing cause.
s i
93NCRWP\\93MMN013.PGD Page 5
of 18
i NCR DC2-93-MM-N013 00 May 28, 1993 2.
Equipment / Material:
a.
Material Degradation:
N/A.
i 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:
Personnel error, failure to follow the procedure (ref. 6) c l
to verify the absence of a containment equipment hatch seal gap from the outside of containment.
D.
Contributory Cause:
1.
Independent verifications were not required for the i
containment equipment hatch closure prior to core off-load.
2.
The Mechanical Maintenance tailboard prior to the containment equipment hatch closure activity was not adequate; visual verification that there was no gap at the hatch sealing area from outside*of containment
<a was not discussed.
IV.
Analysis of the Event A.
Safety Analysis:
An analysis of the consequences of an accident-during core off-load, based on the estimated flow rate out of the equipment hatch under post-accident conditions, with the gap that was observed in.the equipment hatch was performed.
This estimate included an-assumed temperature l
difference between the inside containment atmosphere and ambient throughout the postulated event and resulted in a calculated leak rate of-34 cubic feet per minute (CFM).
This result was combined with the design basis fuel handling accident source-term and meteorological-assumptions to calculate postulated. site boundary doses estimates.
93NCRWP\\93MMN013.PGD Page 6
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NCR DC2-93-MM-N013 00 May 28, 1993 The resulting dose estimates are less than 10. percent of the 10 CFR 100 limits.
Consequently, the analysis of the postulated fuel handling accident with the containment equipment hatch seal breached as' occurred in this event has shown that the resulting Site boundary dose would be bounded by the results of accidents analyzed in the FSAR Update.
Thus, the health and safety of the public were not adversely affected by this event.
B.
Reportability:
1.
Reviewed under QAP-15.B, "Nonconformances," and-determined to be non-conforming in accordance with Section 2.1.2.
2.
Reviewed under 10 CFR 50.72 and 10 CFR 50.73 per j
NUREG 1022 and determined to be reportable in accordance with 10 CFR 50.72 (b) (2) (iii) (C) and 10 CFR 50.73 (a) (2) (v) (C).
See LER 2-93-003-00-(ref. 10) for more information.
Draft and transmit an LER to the NRC for this event.
RESPONSIBILITY: J. Nolan DEPARTMENT:
Regulatory Compliance TRACKING AR:
A0298388, AE # 06 STATUS:
COMPLETE 3.
This problem will not require a 10 CFR 21 report.
4.
This problem will not be reported via an INPO Nuclear l
Network entry.
5.
Reviewed under 10 CFR 50.9 and determined the event was not reportable.
6.
Reviewed under the criteria of administrative procedure (AP) C-29, " Operability Evaluation,"
requiring the issue and approval of an OE and determined that an OE is not required.
~
V.
Corrective Actions A.
Immediate Corrective Actions:
1.
Core off-load was immediately suspended.
2.
The four bolts positioning the containment equipment hatch were retorqued and eight additional, equally 93NCRWP\\93MMN013.PGD Page 7
of 18 t
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o NCR:DC2-93-MM-N013 00 May 28, 1993 spaced. bolts were installed and torqued.
The. sealing area of the equipment-hatch'was inspected and.the i
absence of a gap was verified from outside of containment (ref. 4).
'3.
Tailboard Mechanical Maintenance personnel on.the necessity of procedure adherence RESPONSIBILITY: J. Bard DEPARTMENT:
Mechanical Maintenance (PGMT)
TRACKING AR:
A0298388, AE-# 07 STATUS:
RETURN B.
Investigative Actions:
J 1.
Determine the requirements for closing the j
containment equipmentLhatch in an emergency situation, i.e., how many bolts' must be nade-up, and torqued.
RESPONSIBILITY: J. Hinds DEPARTMENT:
Mechanical Maintenance (PGMX)
TRACKING AR:
A0298388, AE # 01 STATUS:
RETURN l
2.
Perform a preliminary determinationi(i.e.,.best' i
engineering judgement") of the radiological consequences, as specifically related-to the health and safety of the public, of a-fuel damage accident-that could have occurred during fuel movement with-the containment equipment not: fully closed between March 11, 1993 at-1408 pm PST and March 12,;.1993 at 1416 pm PST.
RESPONSIBILITY: T. Mack DEPARTMENT:
NOSRECE (NORX)
TRACKING AR:
A0298388, AE # 02-STATUS:
COMPLETE 3.
Provide a radiological safety evaluation for the' Unit 2 core alteration event described in NCR DC2-93-MM-N013, that occurred between March-11, 19931at_1408.pm PST and March'12,;1993 at 1416 pm PST.
RESPONSIBILITY: T. Mack DEPARTMENT:
_NOSRECE (NORX)-
TRACKING AR:
-A0298388, AE # 03 STATUS:
COMPLETE 4.
Perform a' human factors review of.the event described'-
in NCR DC2-93-MM-N013.
93NCRWP\\93MMN013.PGD.
Page. 8 of '18
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O NCR DC2-93-MM-N013 00 May 28, 1993 RESPONSIBILITY:
K. Doss DEPARTMENT:
Human Factors Eng.(PTMT)
TRACKING AR:
A0298388, AE # 04 STATUS:
COMPLETE.
5.
Quality Control to investigate and report to the TRG the reason that there is no independent verification of the containment' hatch. closure-immediately prior to starting core o#
load, censidering that ther: is independent verification for all other containment equipment hatch closure evolutions (excepting emergency closure).
RESPONSIBILITY:
N.
Koellish DEPARTMENT:
Quality Control-(PQCE)
TRACKING AR:
A0298388, AE # 05 STATUS:
RETURN.
6.
QA to determine if evidence exists to indicate that procedure data sheets are too complicated and thus result in personnel not understanding what their signature is meant to certify.
RESPONSIBILITY: A. Hardy DEPARTMENT:
Quality Assurance (QAAM)-
TRACKING AR:
A0298388, AE # 08 STATUS:
RETURN 7.
QC to investigate the selection criteria for non-mandatory hold-point (independent verification) inclusion in maintenance procedure activities for-reporting to the TRG.
RESPONSIBILITY: N.
Koellish i
DEPARTMENT:
Quality Control (PQCE) i TRACKING AR:
A0298388, AE # 09 STATUS:
RETURN C.
Corrective Actions to Prevent Recurrence:
4 1.
Revise MP M-45.1 to include visual, independent verification of containment equipment hatch closure from outside of containment hold-points (Foreman or QC) and to include the making-up of at least 12-l equally spaced hatch. bolts for equipment hatch closures required for containment ventilation system engineered control.
I RESPONSIBILITY:
C.
Pendleton ECD: 8/15/93 DEPARTMENT:
Mechanical Maintenance (PGMX)
TRACKING AR:
A0298388, AE # 10 93NCRWP\\93MMN013.PGD Page 9
of 18
NCR DC2-93-MM-N013 00 May 28, 1993 STATUS:
ASSIGNED Not outage related.
Not OE related.
An NRC commitment; see ref. 10.
A CMD commitment; see ref. 10.
2.
Counsel Maintenance personnel involved in the Unit 2 equipment hatch event in accordance with the PG&E positive discipline program.
RESPONSIBILITY: J. Bard DEPARTMENT:
Mechanical Maintenance ( PGMT)-
TRACKING AR:
A0298388, AE # 11 STATUS:
RETURN Not outage related.
Not OE related.
i An NRC commitment; see ref. 10.
A CMD commitment; see ref. 10.
4.
Revise procedure AD8.DC54 to refer to M-45.1 to include the steps required for Mode 5/6 closure of the containment eqv.ipment hatch.
Clarify the composition of the containment hatch closure team and specify the command and control for j
emergency closure.
RESPONSIBILITY:
D. Armstrong ECD: 8/15/93 DEPARTMENT:
Planning and Scheduling (PTPS)
TRACKING AR:
A0298388, AE # 12 STATUS:
ASSIGNED Not outage related.
Not OE related.
-n au Not an NRC commitment.
j Not a CMD commitment.
8.
Present to each maintenance crew the HPES crew presentations (HPES Report # 93-06 Corrective Actions) to cover the subjects on tailboards/ pre-job briefings, procedural use and adherence, and work coordination / direction.
RESPONSIBILITY:
K. Oliver-ECD: 08/15/93 DEPARTMENT:
Human Factors Eng. (PTMT)
TRACKING AR:
A0298388, AE # 13 STATUS:
ASSIGNED D.
Prudent Actions (not required for NCR closure):
1.
QC will review the QCP 10.2 to take Technical Specification requirements into consideration when determining verification requirements.
93NCRWP\\93MMN013.PGD Page 10 of 18 I
i NCR DC2-93-MM-N013 00 May 28, 1993 l
RESPONSIBILITY: R. Cramins (PQCI) ECD: 7/4/93 DEPARTMENT:
QUALITY CONTROL TRACKING AR:
A0301758 l
2.
Implement DCNs DC2-EC-48876 (Unit.2) and DC1-EC-47876 (Unit 1) to install rigging points and permanent ladders for use during closure of the containment equipment hatch.
I RESPONSIBILITY: J. Hinds (PGMX)
ECD: 7/4/93 i
DEPARTMENT:
MECHANICAL MAINTENANCE TRACKING AR:
A301762 VI.
Additional Information A.
Failed Components:
None.
B.
Previous Similar Events:
LER 1-83-028-00, December 2, 1983.
Corrective actions included revision of maintenance procedure (MP) M-22 to
... inspection of the equipment hatch in greater l
include:
detail to ensure closure and add additional bolts as l
necessary to assure that there are no visible air gaps on the sealing surface." (ref. 5).
C.
Operating Experience Review:
1.
NPRDS:
N/A.
2.
NRC Information Notices, Bulletins, Generic Letters:
NRC Information Notice 79-33, " IMPROPER CLOSURE OF PRIMARY CONTAINMENT EQUIPMENT ACCESS HATCHES,"
describes an event at Brown's Ferry when the equipment hatch was not fully closed.
3.
None.
D.
Trend Code:
Responsible department MM, and cause code A1.
i 93NCRWP\\93MMN013.PGD Page 11 of 18
}
i b
NCR DC2-93-MM-N013 00 May 28, 1993 i
E.
Corrective Action Tracking:
1.
The tracking action request is A0298388.
2.
Corrective actions are not solely outage related.
F.
Footnotes and Special Comments:
None.
G.
References:
1.
W/O R0094908.
2.
OP B-8D, " REFUELING PREREQUISITES."
3.
j 4.
Personnel statement, S. Watkins, March 15, 1993.
5.
LER 1-83-028-00.
6.
MP M-45.1,
" CONTAINMENT EQUIPMENT HATCH DOOR OPENING AND CLOSING."
7.
Initiating Action Request A0297874.
8.
Discharge Permit 93-2-19.
1 9.
Personal communication J. Nolan to M. Rhodes, March 17, 1993.
- 10. LER 2-93-003-00, "UlilT 2 CONTAINMEh EQUIPMENT HATCH NOT FULLY CLOSED DURING CORE OFF-LOAD."
4 H.
TRG Meeting Minutes:
1.
On March 17, 1993, the TRG met in room 533 of the administration building at 10:00 am PST.
Personnel-involved in the event were interviewed and investigative actions were assigned as noted herein.
The preliminary root cause for the event was agreed to be personnel error, failure to follow the applicable procedure.
The TRG plans to reconvene on or about March 25, 1993.
2.
On March 25, 1993, the TRG met in room 302 of the administration building at 10:00 am PST.
Causes:of 93NCRWP\\93MMN013.PGD Page 12 of 18 i
~
1 i
NCR DC2-93-MM-N013 00 May 28, 1993-the event were discussed and the root cause was determined.to be personnel error, as noted herein.
Corrective actions were assigned, as well'as additional investigative actions.
The-TRG plans to reconvene on or about April 1, 1993, to discuss pending safety issues, procedure revisions and to sign-off the LER (due to the NRC April 9, 1993).
3.
On April 1, 199' at 10:00 am PST'in room 214 of the-administration building the TRG reconvened to discuss additional corrective actions that will complete the response to this event.
A corrective action to revise the Safety Plan and two prudent actions.as noted herein were assigned.
No TRG. reconvene is planned at this time.
An ECD for this NCR will be determined later.
On April 5, 1993, LER:2-93-003-00 was; submitted to l
the NRC via PG&E letter DCL-93-076.
4.
On May 28, 1993, at 10:00 am PST in room 425.of the administration building the TRG reconvened and reviewed the HPES report # 93-06 corrective actions.
It was decided to close Investigative Action AE # 4 and write another AE (AE # 13) to present to each maintenance crew the HPES; Report # 93-06 which covers-the subjects on tailboards/ pre-job briefings, procedural use and adherence, and work coordination / direction.
It was agreed to add in AE # 12'to incl"ie in.the revision of procedure AD8.DC54 clarification ~of the composition of the containment hatch closure team and specify the command and control for emergency closure.
The TRG adjourned at 11:50 PDT.
THE TRG IS NOT TO RECONVENE. THE TRG SECRETARY TO SUBMIT THE NCR FOR COMMENTS'BY THE TRG MEMBERS.
TRG MEMBERS TO SUBMIT THEIR COMMENTS TO THE SECRETARY BY JUNE 8.
1993.
UPON INCORPORATION OF THE COMMENTS. THE TRG VOTING MEMBERS WILL BE ADVISED TO COME AND SIGN THE NCR. BEFORE SUBMITTAL TO THE PSRC AND SUBSEQUENT CLOSURE BY QA.
TRG CLOSURE ECD:
09/30/93.
93NCRWP\\93MMN013.PGD Page 13 of 18
I NCR DC2-93-MM-N013 00 May 28, 1993 i
I.
Remarks:
None.
J.
Attachment:
l ROOT CAUSE ANALYSIS FOR NCR DC2-93-MM-N013 l
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93NCRWP\\93MMN013.PGD Page 14
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ROOT CAUSE ANALYSIS FOR NCR DC2-93-MM-N013 EFFECT CAUSE EVIDENCE BARRIER T.S.
3.9.4a violated 1.
Fuel movement in progress Personnel
- 2. Gap in the equipment statement by hatch refueling SRO 1.
Fuel movement in 1.1 Unloading the core CC1 OP B-8D did not progress prevent the T.S.
violation Unloading the core ROOT CAUSE: Refueling the-reactor
- 2. Gap in the equipment 2.1.
Bolts were not evenly Personnel CC2 MP M-45.1 step hatch spaced statement by 7.2.4-not followed refueling SRO CC3 No independent verification CC4 MP.M-45.1 App 8.1 was signed w/o completion of steps CC5 MP M-45.1 was not followed Proposed: Independet closure-verification i
2.1 Bolts were'not evenly Mechanic placed bolts that Personnel spaced were within reach-
~ statement by refueling.SRO Mechanic placed bolts that 2.1.2' Safer to do bolts that Personnel ~
Potential:
1.
Specify..
were within reach are within reach statement by which bolts are to.be 2.1.2 He thought the bolts MM; journeyman tightened in the were evenly spaced enough
~
procedure or!on the-hatch
- 2. Specify tightening more than14 bolts by procedure 93NCRWP\\93MMN013.PGD Page 15 of 18-
=-
~ -. -
I EFFECT CAUSE EVIDENCE BARRIER 2.1.1 Safer to do bolts ROOT CAUSE: Only requires a Personnel Potential:
1.
Install that are within reach ladder and no special statement by special rigging rigging available MM journeyman 2.1.2 He thought the bolts ROOT CAUSE: Human error -
MM journeyman CC6 Tailboard was were evenly spaced enough knowledge exceeded statement in inadequate TRG
- CC1 OP B-8D did not The hatch was signed off by-nP B-8D prevent the T.S. violation MM OCC rep The hatch was signed off by Told by the MM foreman that Verbal MM OCC rep installation step was comp statement by MM OCC rep Told by the MM foreman that Foreman thought that the job Verbal Potential: Independent installation step was was complete statement by verification complete MM foreman Foreman thought that the Foreman saw the job signed W/O &
job was complete off in the work order and in appendix B.1 App. 8.1 sign offs
- CC2 MP M-45.1 step 7.2.4 Inspection from outside Personnel Potential: Independent was not followed containment not performed statement by verification MM journeyman Inspection from outside Mechanic thought inside Personnel CC6 Tailboard was containment not performed inspection was okay statement by inadequate MM journeyman Mechanic thought inside Human error - inattention to Potential: Counseling inspection was okay detail 93NCRWP\\93MMN013.PGD Page 16 of 18
EFFECT CAUSE EVIDENCE BARRIER
- CC3 No independent There was no verification of W/O R0094908 verification, this step There was no verification 1.
Inspection for this job Potential: Make the of this step is optional inspection mandatory 2.
QC planner decided no inspection was necessary 1.
Inspection for this job Programatic aspect Selection criteria is optional less than effective.
Programatic aspect Manpower limitations
- 2. QC planner decided no No inspection failure in the inspection was necessary previous 9 years
- CC4 MP M-45.1 App. 8.1 Steps were signed off w/o Appendix 8.1 CC7 Foreman's review did not prevent the T.S.
being performed didn't prevent violation Steps were signed off w/o Mechanic thought the job was being performed done correctly Mechanic thought the job Human error - inattention to Potential: Counseling was done correctly detail
- CC5 MP M-45.1 not Mechanic performed the task Potential: Emphasize followed from memory AD2.ID1 requirement w/MM personnel Mechanic performed the task More convenient than taking MM journeyman from memory the procedure into statement in containment the TRG More convenient than taking Paperwork has to be frisked the procedure into out containment 93NCRWP\\93MMN013.PGD Page 17 of 18
EFFECT CAUSE EVIDENCE BARRIER
- CC6 Inadequate tailboard Didn't discuss the MM foreman inspection or the statement in significance of the job the TRG Didn't discuss the Didn't take the time to be inspection or the thorough significance of the job Didn't take the time to be Human error - inattention to Potential: Counseling thorough detail
- CC7 Foremen's review Review performed was not didn't prevent thorough Review performed was not Human error - inattention to Potential: Counseling thorough detail r
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93NCRWP\\93MMN013.PGD fl age 18 of 18
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