ML20198L243
| ML20198L243 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 05/30/1986 |
| From: | Greger L, Miller D NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20198L156 | List: |
| References | |
| 50-254-86-06-01, 50-254-86-6-1, NUDOCS 8606040244 | |
| Download: ML20198L243 (8) | |
See also: IR 05000254/1986006
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U.S. NUCLEAR REGULATORY COMMISSION
REGION III
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Report No. 50-254/86006(DRSS)
Docket No. 50-254
License No. OPR-29
Licensee:
Commonwealth Edison Company
Post Office Box 767
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Chicago, IL 60690
Facility Name: Quad Cities Nuclear Power Station, Unit 1
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Inspection At: Quad Cities Site, Cordova, IL
Inspection Conducted:
March 31, April 1, and May 16, 1986
Inspector:
D
6-N-O
Date
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Approved By:
L. R. Greger, Chief
5~~ 30 ~l2d'
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Facilities Radiation Protection
Date
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Section
Inspection Summary
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Inspection during the period March 31 through May 16, 1986 (Report
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No. 50-254/86006(DRSS))
Areas Inspected:
Nonroutine, announced inspection of an Intermediate Range
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Monitor (IRM) handling incident that occurred on March 27, 1986, during removal
of IRM 17 from the Unit 1 reactor vessel.
Results:
One violation was identified (failure to perform surveys to evaluate
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extent of radiation hazards - Section 5).
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DETAILS
1.
Persons Contacted
- R. Bax, Station Manager
- R. Carson, Lead Health Physicist
B. Dickherber, Fuel Handling Foreman
- C. Norton, QA Engineer
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C. Richardson, Instrument Maintenance Foreman
- R. Roby, Services Superintendent
J. Rosenow, Radiation Protection Foreman
- J.
Sirovy, Rad / Chem Supervisor
- G. Spedl, Assistant Superintendent, Technical Services
R. Venci, Health Physicist
- A. Madison, NRC Senior Resident Inspector
Also contacted were several other licensee employees.
- Denotes those present at the exit meeting conducted by telephone on
May 16, 1986.
2.
General
This inspection, which began at 9:30 a.m., on March 31, 1986, was conducted
to examine a handling incident that occurred during removal of an irradiated
intermediate range monitor from the Unit 1 reactor vessel on March 27, 1986.
The inspector interviewed the major participants in the event, observed a
reenactment of the handling incident, observed a videotape of a portion of
the event, and discussed the incident with licensee rad / chem managers and
supervisors.
No exposures in excess of regulatory limits resulted from the
handling of the intermediate range monitor.
3.
Summary of Intermediate Range Monitor (IRM) Removal Incident
During recent power operation, the licensee had experienced difficulty
remotely positioning IRM 17 in the core; this IRM had been in service for
about eight years.
During this outage, the IRM was to be removed from the
reactor and the guide tubes inspected to determine the cause of the
positioning problems.
The IRM was not to be reused after removal.
IRMs and their drive cables are encased in fiberglass sleeves; the sleeves'
main purpose is to insulate electrically the IRM and cable from the guide
tubes.
Until about five years ago, two sleeves (one over top of the other)
were used.
The IRM vendor then suggested use of only one sleeve; since
then, one sleeve has been used on replacement IRMs.
Use of two sleeves may
have contributed to sticking of the IRM during operation and removal.
The
drive cable is one quarter inch in diameter and composed mostly of copper.
The detector is the same diameter and less than one-inch long.
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During 1985 and 1986 to date, six IRMs were removed without incident.
The
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removal procedures, techniques;lan'd equipmes.t for the removal of the sub-
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Ject IRM on March 27, 1986, were similar to those previously used.
However,
unexpected difficulties were experienced while removing IRM 17 from Unit 1.
Removal of IRM 17 was abnormal in that it hung op in the guide tube while
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being pulled out by hand, and hung up twice in the shielding cask take-up
reel while being remotely reeled into temporary shielded storage. When the
cable stuck in the take up reel the second time, about seven feet of cable
with the IRM detector on the end remained exposed.
At this point the fuel
handler acted without consultation with others, to sever the cable and
- manually place the detecter and approximately three feet of cable into the
' shielded transport container.
Remote cutting or handling tools were not
used. Although radiation exposures as a result of the specific incident
did not exceed regulatory limits, no surveys were made of the portion of
the cable manually handled by the fuel handler.
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A discussion of various aspects of the incident is presented in the
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following sections of this report.
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4.
Planning and Qualifications
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The licensee maintains an ALARA job file for IRM removals.
The file
containh a history of removals performed in the past two or three years
including the dose rates encountered; post-job critiques; recommendations;
and a training folder which contains a description of the job with
photographs,.a sequence of events during IRM removals, and precautions.
The Rad / Chem _ Technician (RCT) assigned to support the fuel handling group
dur-ing removal of IRM 17 had not previously covered an IRM removal.
In
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preparation for the job, he completed the following actions.
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Reviewed fuel handling Procedure QFP 600-3, IRM and SRM Handling.
Reviewed the ALARA job file for IRM removal.
Discussed the job with a radiation protection foreman; the foreman
had previously been a fuel handler and was familiar with the job.
Discussed the job with another RCT who previously covered an IRM
removal.
Discussed the job with the fuel handlers who would perform the removal.
Responsecheckedtheportailesurveyinstrumentstobeused.
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The fuel handlers assigned to IRM 17 removal were experienced in incore
detector removals.
Their preparation for IRM 17 removal included tha
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following actions.
Reyiew of Procedure QFP 600-3.
Discyssion of the job with the RCT who would provide radiation protection
job ceverage.
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Assembling of the equipment to be used including extra take-up reels for
the TIP cask; the extra reels to be used if problems were encountered.
Operational checkout of the equipment.
The fuel handling foreman met with the radiation protection foreman to
discuss Procedure QFP 600-3, IRM and SRM Handling, before the start of
the job.
Because of the lack of problems encountered during previous IRM and SRM
removals, the preparations did not include discussions of corrective
actions needed to respond to the problems that were encountered during
removal of IRM 17.
Coincidentally, a health physicist and a rad / chem foreman videotaped
removal of IRM 17.
The videotape is to be used to provide an additional
training tool for future IRM and SRM removals.
Consequently, most of the
observable problems encountered during removal of IRM 17 were recorded on
videotape and could be reobserved without reenactment.
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5.
Chronology of Events During IRM 17 Removal
Lis^-'d below is a chronology of events during removal of IRM 17 on
March 27, 1986, and followups to the event on later days.
Portions of the
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preparation and removal process that were normal and uneventful are only
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briefly described.
Planning and assembly / testing of equipment was completed.
The transfer cask was rolled into place in the drywell ante room.
All unnecessary persunnel were removed from the drywell.
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Two fuel handlers, the RCT, and the Health Physicist and Radiation
Protection foreman (who would videotape the IRM removal) entered the
drywell; they wore rubber gear and full face respirators.
The drywell
coolers were running; communications were poor because of noise and
wearing of respirators.
The fuel handlers installed a tygon tube (use to prevent kinking of
the cable), installed plastic sleeving to be used while pulling the
detector cable, and began the cable pull.
The RCT, using a teletector
(extendable probe portable survey instrument), monitored the cable
near the IRM guide tube; when the reading reached about 200 mr/hr, the
RCT motioned the fuel handler who stopped pulling, cut off the cable,
and bagged the withdrawn, cut-off, portion.
The fuel handler then
prepared the end of the remaining inserted cable so that it could
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later be attached to the " fish tape" on the shielded cask take-up reel.
'At this point, less than 15 feet of cable should have remained to be
pulled from the reactor vessel.
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The sleeving was attached to the end of the cable (for contamination
control).
The next step normally is to pull the remaining cable with
the detector on the far end, drag it (encased in plastic tubing) to
the transfer cask, attach cable end to fish tape, and reel-in
(remotely) the cable and detector into the transfer cask.
In this
case, the cable stuck when partly pulled; the RCT motioned the crew to
retreat to a low dose rate area to plan the next step.
After resurveys
were made and another attempt to pull the cable was made, one fuel
handler went under the platform and pulled the cable straight down;
the cable came loose.
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A fuel handler then hastily pulled the cable and detector, as usual,
while the radiation readings were measured by the RCT. The fuel
handler pulled the cable and detector so quickly that the other
members of the work and videotape crew lost track of where the
detector was and for a brief period walked / stood nearer to the cable
and detector than necessary to perform their duties.
As measured with
the teletector, contact dose rate on the cable near (about 4 feet) the
detector was about 100 R/hr, and 300 R/hr at contact with the detector.
The dose rates at one foot were about a factor of 100 less; this dose
rate information was not known by the fuel handler.
A fuel handler attached the cable to the " fish tape" and remotely
began reeling the cable into the transfer cask.
After take-up of
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several feet, the process stopped; the machine appeared jammed.
The
fuel handler cut the cable close to the cask, put into the cask
another take-up reel, attached the cable, and again began the reeling
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in process.
The machine again appeared jammed (after take-up of one
foot) with about seven feet of cable (with the detector on the far
end) remaining out of the cask.
The detector was between the fuel
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handler and the remainder of the work group, who were on the other
side of the drywell interlock door.
The dose rate at the interlock
door was about one R/hr.
After a short pause, the fuel handler severed the cable near the cask,
removed the take-up reel from the cask, moved down the cable about
four feet and cut it again, grabbed the remaining approximate three
feet of cable, with the detector attached, and guided the detector
into the transfer cask.
He stuffed the cable which remained attached
to the detector into the cask and closed the cask shielding doors.
A
later reenactment showed the final cut and transfer to the cask was
performed in less than five seconds.
A short while after the detector was placed in the shielded
transfer cask, the four-foot section of cable which had been cut
earlier to facilitate manual handling of the detector was discovered
to be causing excessive radiation levels (120 R/hr contact) in the
drywell ante room.
After evacuating the area to evaluate retrieval
options, the remaining four feet of cable was retrieved by remote
cutting and handling.
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During this evolution, no surveys or evaluations were made to evaluate the
radiation hazards incident to the evaluation.
Consequently, the doses
received by the fuel handler were not planned or controlled, and admini-
strative dose limits were exceeded.
Failure to perform surveys that were
reasonable under the circumstances to evaluate the radiation hazards is
considered a violation of 10 CFR 20.201(b).
(254/86006-01)
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6.
Dose Adjustments
Because of the abnormal handling experienced, several whole body and
extremity dose adjustments were necessary to account for doses received
that were greater than the dose monitored by the whole body and extremity
dosimetry.
No doses in excess of 10 CFR 20.10(a) resulted from the dose
adjustments.
The inspector reviewed the licensee's dose adjustment methods and
calculations; no problems were noted.
7.
Investigation Conclusions (Licensee's)
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As a result of their investigation into this incident, the licensee
identified the following problems.
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Although dosimetry placement was proper for a normal IRM removal, the
dosimetry placement was improper for the abnormal circumstances
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encountered in this incident.
The fuel handler's decision to act on his own and complete the
transfer by hand was predicated on his on-the-spot conclusion that by
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doing so he would avoid unnecessary radiation exposure to the other
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participants in the IRM task.
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Direct radiation monitoring was poor during the latter states of the
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removal of the IRM because the removal was abnormal and because of
the positioning of the participants.
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Rad / chem technicians and others do not have a good understanding of
contact dose rate terminology and meaning.
Communications were poor because full face respirators were worn and
the drywell coolers were operating.
The noise level was high and
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there was no supplemental method of communication other than hand
signals.
Although the RCT assigned to cover the IRM removal was trained and
adequately briefed, he had not previously monitored an IRM removal.
In this case, it appears that the RCT's decision to allow work to
continue was influenced by the experience level of the two fuel
handlers performing the work.
Neither procedures nor preplanning anticipated the type of problem
encountered.
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8.
Recommendations Resulting From Investigation (Licensee's)
As a result of their investigation into this incident, the licensee
recommended the following corrective measures.
Investigate methods of improving communications during IRM removals.
Better educate RCTs and other station personnel about true dose rates
at contact with sources of radiation.
Have all RCTs and fuel handling personnel view the videotape of
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IRM 17 removal and point out the problems and mistakes to them.
Use INPO resources to review industry experience with incore
detectors and investigate removal methods.
Develop a standard Radiation Work Permit for removal of incore
detectors and include special instruction and guidelines.
Revise IRM and SRM handling procedures to include instructions
concerning positioning of personnel during procedure implementation,
and to require a fuel handling foreman to be in the drywell to
provide management guidance in cases where problems develop.
Improve radiation protection and fuel handling personnel training
concerning incore detector functions, develop indicators to predict
potential problems, and update training guides.
Review equipment used in IRM removal to determine adequacy and
reliability, and make necessary changes / alterations.
Review IRM past performance and replacement history to determine if
there are performance trends that could indicate potential removal
problems.
9.
Additional Corrective Actions
As a result of the inspector's review of this incident, the following
additional corrective actions appear appropriate to preclude recurrence
of similar incidents.
These actions were discussed with the licensee
prior to and during the telecon exit meeting.
Radiation Chemistry Technicians (RCTs) should be reinstructed in
their authority and responsibility to terminate work in progress
when adverse unplanned radiological conditions arise.
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RCTs should be better trained to provide radiological job coverage of
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IRM removals.
Training should include observation of a removal before
being assigned to such job coverage.
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10.
Exit Meeting
The inspector conducted a telecon exit meeting with the licensee at the
conclusion of the inspection on May 16, 1986.
The inspector discussed the
scope and findings of the inspection.
The inspector also discussed the
likely information content of the inspection report with regard to documents
or processes reviewed by the inspector during the inspection.
The licensee
identified no such documents / processes as proprietary.
In response to
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certain matters discussed, the licensee:
a.
Acknowledged the violation.
(Section 5)
b.
Stated that the recommendations listed in their " Report of the
Radiation Chemistry Department Investigation of a Radiation Occurrence
to a Radiation Protection / Fuel Handling Work Group in the Unit 1
Dryweil on Thursday, March 27, 1986," would be implemented as commit-
ments in accordance with the following schedule.
The commitments will
be implemented by July 30, 1986, except for Items 8 and 11.
Item 11
will be implemented by August 30, 1986.
Item 8 involves a long-term
review.
(254/86006-02)
c.
Stated that the additional corrective actions listed in Section 9
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would be implemented as commitments.
The first item will be completed
by June 15, 1986, and the second item will be ongoing.
(254/86006-03)
d.
Acknowledged the inspector's comment that the investigation of
the incident was timely and thorough, and the conclusions and
recommendations appeared appropriate.
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