ML18152A143
| ML18152A143 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 04/15/1988 |
| From: | Bassett C, Hosey C NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | |
| Shared Package | |
| ML18152A144 | List: |
| References | |
| 50-280-88-10, 50-281-88-10, NUDOCS 8804260075 | |
| Download: ML18152A143 (25) | |
See also: IR 05000280/1988010
Text
UNITED STATES
NUCLEAR REGULATORY COMMISSION
REGION II
101 MARIETTA ST., N.W.
ATLANTA, GEORGIA 30323
APR i 8 1988
R~port Nos.:
50-280/88-10 and 50-281/88-10
Licensee: Virginia Electric and Power Company
Richmond, VA
23261
Docket Nos.:
50-280, 50-281-
License Nos.:
Facility Name:
Surry
Inspection Conducted:
March 5-11 and 23-25, 1988
Inspector:
C1!:,~-
C. H. Bassett
Accompanying Personnel:
C. Hinson
Approved by: ~ /~ {!;).tdd';J~
- M.
osey, Se~on Chief
Division af Radiation Safety and Safeguards
SUMMARY
Date Signed
Scope:
This special, announced inspection was conducted to review potential
radiation exposures in excess of NRC limits associated with the freeing of an
incore detector which had become lodged in a thimble tube in the core of the
Unit 2 reactor.
Results: Three*violations were identified - failure to adequately evaluate the
radiation hazards present during work on an incore detector, inadequate
procedures for freeing the incore detector and for briefing those involved in
the work and failure to conduct operations in accordance with approved
procedures *
8804260075 880418
PDF~
ADCICK 050002:30 *
Q
REPORT DETAILS
- 1.
Persons Contacted
2.
Licensee Employees
- W. Bartlett, Senior Staff Health Physicist~ Corporate
- D. Benson, Station Manager
R. Berryman, Director, Fuels Group, Corporate
R. Biskey, H~alth Physics Technician
- R. Blount, Superintendent, Technical Services
- W. Cameron, Director, Corporate Health Physics
W. Cook, Operations Supervisor, Health Physics
- E. Ferreria, Supervisor, Instruments
- E. Grecheck, Assistant Station Manager, Nuclear Safety and Licensing
wH. Miller, Assistant Station Manager, Operations and Maintenance
K. Niles, Lead Instrument Technician
L. Pettaway, Shift Supervisor, Health Physics
- J. Price, Manager, Quality Assurance
- S. Sarver, Superintendent, Health Physics
- E. Shaub, Licensing Engineer, Corporate
K. Stacy, Instrument Technician
T. Stafford, Instrument Technician
- T. Stallings, Supervisor, Instrumentation and Control
- W. Stewart, Vice President, Nuclear Operations
R. Thomas, Senior Engineer, Corporate.
Other licensee employees contacted included engineers, technicians,
operators, security office members, and office personnel.
Nuclear Regulatory Commission
- F. Cantrell, Section Chief, Division of Reactor.Projects
- W. Holland, Senior Resident Inspector
- L. Nicholson, Resident Inspector
- Attended exit interview on March-lJ, 1988 *
0 --
- Attended exit interview .on March 25, 1988
Exit Interview (30703)
The inspection scope and. findings were summarized on March 11, and on
March 25, 198S,-with those persons indicated in Paragraph 1 above.
Three
apparent violations, (1) fa*ilure to evaluate the radiation hazards
resulting from work on an incore detector (Paragraph 3.d.(1)); (2) failure
to provide adequate procedures for removal of an incore detector and for
briefing personnel performing work coverage (Paragraph 3.d.(3)) and
(3) failure to adhere to approved procedures (Paragraph 3.d.(4)), were
discussed in detail. *The licensee's assessment and assignment of whole
2
_ body and extremity dose was designated as an unresolved item* pending NRC
review (Paragraph 3.d.(5)).
The licensee acknowledged the inspection
findings and took no exceptions, but stated that they believed only one
problem or violation had occurred, that of an improper-assessment of the
source and the source strength of the stuck detector and cable.
NRC concerns relative to the inspection findings were discussed by
D. M. Collins of this office with R. Berryman, Director, Fuels Group and
Manager of the Incore Detector Event Investigation Team, in a telephone
conversation on March 18, 1988.
During this conversation, the NRC was
informed of further corrective actions taken, planned and/or under
consideration with regard to preventing future exposures to very high
radiation levels due to detector replacement or other operations where
such exposure might be possible.
Those actions included:
(1) formation
of a licensee task force to investigate the incore detector event, (2)
documentation of the events, (3) construction of a mock-up and videotaping
a reenactment of the event, (4) finalizing radiation dose calculation,
(5) evaluation of the adequacy of procedures used during potentially high
radiation exposure jobs, ( 6) determination whether procedures were -
f o 11 owed, the adequacy of the pre-job briefing and whether any NRC
regulations or Technica.l Specification requirements were violated,
(7) releasing *information
to
industry concerning the event,
(8) determination whether further corrective actions are warranted, and
. (9) preparation of a final report on the event.
During an enforcement conference on March 28, 1988, held on an unrelated
subject, the licensee made a presentation on the incore detector event. A
brief-overview of the event was given and the scope, schedule and status
of the ongoing investigation were outlined.
Preliminary dose estimates
- for the three workers involved were given as follows:
whole body doses
( above the knee) ranged from 800-1600 mi 11 i rem, extremity doses ( 1 ower
legs) ranged from 820-1600 millirem and a dose of 800 millirem to the hand
of the individual who held and pulled the cable.
The licensee indicated
that these exposure estimates were very conservative and would probably be
reduced when all the data were analyzed and the final calculation made.
The licensee stated further that the exposure estimates would be reviewed
by an independent vendor organization outside the corporate structure.
(Attached. is a copy of the material presented by the licensee on the
subject of the Incore Detector Event.)
3.
Inspector Followup on Significant Events (93701)
a. Synopsis of -the Incore Detector Event.
During the morning of March 3, 1988, two*instrument and control (I&C)
technicians and one health physics (HP) technician entered the Unit 2
containment to perform what was considered to be minor maintenance on
- An Unresolved Item is a matter about which more information is required to
determine whether it is acceptable or may involve a violation or deviation.
r
b.
3
the incore flux mapping sy"stem.
Unit 2 was at 100 percent(%) power
and the containment was sub-atmospheric.
The maintenance activity to
be performed included freeing the
11A
11 incore detector (which had
become lodged in a guide thimble in the core), transferring it to a
storage location and replacing that detector and the associated drive
cable with new equipment.
During efforts to dislodge the detector,
abou~ 100 feet of the cable attached to the detector were pulled
through the polar crane wall (bioshield) and t~ken up on the
11A
11
drive unit reel assembly.
As the incore detector was pulled up to
the penetration through the bioshield, the HP technician noted
rapidly increasing radiation levels near the transfer tube which soon
exceeded 1000 rem per hour (R/hr).
He then ordered the work stopped
and an evacuation of the work platform.
The workers*
thermoluninescent dosimeters (TLDs) were subsequently read and the
high.est dose recorded was 524 millirem (mr) to the whole body.
Scenario of the Incore Detector Exposure Event
Through discussions with licensee representatives, interviews with
involved personnel and review of licensee records, the circumstances
surrounding the March 3, 1988 incore detector event were reviewed.
On that date, at approximately 10:00 a.m., two I&C technicians were
briefed by a Lead I&C te_chrii ci an on the maintenance work to be
performed on the Unit 2
11A
11 incore detector and associated drive
cable.
The HP technician, who had been assign~d to cover the job,
was not inc 1 uded in the pre-job briefing. * The maintenance work
consisted of freeing the detector (which was stuck in a thimble tube)
by disconnecting the electrically operated drive box in the
11A
11 drive
unit and manually pulling the helical-wrap drive cable attached to
the detector a few feet to free its movement. The drive box would
then be reassembled so the detector could be retracted from the
vessel and driven to a storage location using normal operation of the
drive unit.
If time permitted, the technicians were to also cut off
the old detector, leaving it in a storage port in the Seal -Table Room
wall and replace it and the drive cable with new equipment.
Following the pre-job briefing and --a _5=ontrol room briefing, the I&C
technicians and the HP technician proceeded to the Change Room to
prepare for the: entry.
As they were preparing to dress out in
protective clothing (PCs), one of the I&C technicians explained the
work scope to the HP technician.
At approximately 11:00 a.m., the three individuals, dressed in
protective clothing and wearing self-contained breathing apparatuses
(SCBAs), prepared to enter containment.
In addition to TLDs, low
range self-reading dosimeters (SRDs) with a range.from 0-200 millirem
and high range SRDs with a range of 0-1500 millirem were used to
monitor personnel exposure.
After passing through the containment
airlock, the three individuals proceeded to the drive unit platform.*
The HP .technician performed a radiation survey on the work area
platform where all the incore detector d~ive units are located. The
general area rad_iation level was found to be 10-20 millirem p*er hour
4
(mr/hr) in the work area.
Following the s.urvey, ~he I&C technicians
were allowed to begin work.
Upon entering the work platform, the technician who was assigned to
pull the drive cable established communications with the control room
using a sound powered head set. Once commun_ications had been set up,
the I&C technicians disconnected the drive box and began to dislodge
the detector.
As one technician knelt down on the platform beside
the drive unit and pulled the detector drive cable, the other stood
by the drive unit and
held the cable uptake re.el assembly so that
the cable would not wind too rapidly.
The HP technician stood
between the
11A
11 drive unit and the polar crane wall and placed the
teletector probe near the cable transfer tube to monitor for any
changes in radiation levels which would indicate what he anticipated
to be crud or hot particles on the cable.
After the cable had been pulled approximately three feet, the drive
box was reconnected and an attempt was made by the Lead I&C
technician in the control room to drive the cabl~ out electrica1ly.
When this attempt failed, the above sequence of disconnecting the
drive box, pulling the cable and reconnecting the drive box was
repeated.
A second attempt to drive the detector out of the vessel **
also failed and the Lead. I&C technician stated that those in
containment would apparently need to continue pulling the cabl~. The
I&C supervisor for the job, who was monitoring the conversation *
between the lead I&C technician in the Control Room and the I&C
technicians at the job site using -a head set, did not object and the
cable pulling continued.
The HP technician covering the work was
not included in the discussion to continue pulling the cable by hand.
The drive cable was pulled until the detector reached the Seal Table
Room.
A radiation monitor alarm was received in the control room at
this time and a rise in the *seal Table Room radiation level was
indicated on the strip chart in the control room documenting the
increasing radiation levels in the area.* The strip chart showed that
the radiation lev~ls in the room rose until a reading of
approximately 10 rem per ho1:Jr (R/hr L was indicated.
The audible
alarm was noted in the control room however, since it had been
anticipated, no additional actions were taken by personnel in the
Control Room.
Once the detector passed what the technician assumed
to be the 10-path transfer rotary device, he noted that there was no
longer any resistance and .that .the detector and cable appeared to
move freely and be past any interferences~ The uptake reel was then
locked in. place with a pin to prevent it from withdrawing the
detector onto the work platform and the cable was pulled by hand more
slowly and in shorter increments.
During this period of cable
retraction, as soon as three or four feet of cable had been pulled
through the polar crane wall, th~ I&C technician who was helping
would unpin the reel, wind the excess cable onto the reel and then
repin the uptake reel to hold it in place.
5
At thts point in the operation, the I&C technicians had problems with
the communications equipment and the pull was suspendeq for about
five minutes.
During this break in communications, the I&C
technicians partially reconnected the drive *box in preparation for
the anticipated termination of this portion of the maintenance task.
- When communications were reestablished, the technician began pulling
the drive cable again, gradually withdrawing it in an attempt to trip
the "withdrawn" limit switch located in the transfer tube.
This
would produce a signal in the contra l room and the Lead I &C
technician would then know that the detector was fully withdrawn.
The 5-path transfer rotary device could then be switched to the
11storag~
11 mode for detector insertion.
In order to pull the cable with the drive box partially reconnected,
the techinician doing the pulling had to hold the drive box apart
slightly with his left hand while pulling drive cable with his right.
Just as the detector apparently passed the limit switch, the Lead I&C
Technician told the technician pulling the cable to stop and
indicated that the "withdrawn" light had come on.
Due to further
communications problems, the Lead I&C technician had to repeat that
warning.
The technician retracting the_ cable stopped pulltng and
waited *to get the word that the selector switch of the 5-path
trans.fer rotary device had been moved to the
11storage
11 position by
the contro1 -room so he could push-the cable and the detector into
storage.
During this same time frame, the HP technician noted that the *
radiation readings he was getting had increased to about 200 millirem
per hour (mr/hr) at a point near contact with the transfer tube in
the
11A
11 drive unit. Then he noted that the radiation levels suddenly
increased as the cable was being withdrawn and he was forced to
change scales on the survey instrument.
The radiation levels
continued to climb and* he again changed scales. The final dose rate
exceed the maximum onscale reading of-the instrument (1000 R/hr) and
he quickly moved the instrument probe to a point near the I&C
technician who was pulling the cable in order to check the work area
radiation level. Realizing-that the *radiat-i*on levels were very high,
he moved around the end of the
11A
11 drive unit and signaled that
everyone should leave the work platform.
Both of the I&C technicians
had noticed that the HP technician had switched scales on the
teletector and that the radiation levels had i-ncreased.
They, too,
were preparing to leave the area.
Just before he stood up, the
technictan who had pulled the cable inserted about six to nine inches
of cable back into the feeder transfer tube and then left the area.
Once everyone had exited the. work platform, the HP Technician read
the high range self-reading dosimeters (SRO) and determined that no
one had received an exposure over approximately 500 millirem (mr).
He then reentered the work area to take confirmatory radiation level
readings. A reading taken at the end of the work platform furtherest
from the
11A
11 drive unit (behind the
11 E
11 drive unit) indicated a
..
6
radiation level of 2 R/hr.
At a point behind the
118
11 drive unit and
approximately six feet from the
11A
11 drive box, the radiation level
was 10 R/hr.
The radiation level approximately three feet from the
drive box was 100 R/hr and general area radiation readings in the
vicinity where the I&C technician had been pulling drive cable were
in excess of 1000 R/hr!
After the survey was completed, the three
technicians exited containment and were debriefed. The individuals 1
TLDs were read with the following results:
Individual
TLD results
SRD result
Previous
(Rem)
(Rem)
Quarter Dose
To Mar 3(Rem)
HP Technician
0.275
0.240
0.124
I&C Tech (pulling)
0.347
o. 500*
0.038
I&C Tech (helping)
0.524
0.550
0.010
A debriefing was held for those involved with the detector event
immediately following their- exit from containment. Later in the
afternoon, the NRC Senior Resident was briefed about the event.
c.
Recovery Operations
On March 7, 1988, preparations were made.to recover from the ~vent
and place the detector into storage.
Th~ lic~nsee fabricated long
handled tools to be used in the recovery effort and provided some
limited training to those who were designated to perform the job. It
was decided to have an HP Supervisor accompany the recovery team to
assist and to further document the survey results obtained.
A
Special Radiation Work Permit, RWP 1159, Incore Detector Recovery,
dated March 7~ 1988,
was written for the recovery which specified
the radiological controls for the job.
Extremity dosimetry was
provided for all personnel and precautions were added which, among
other limitations, allowed no one to enter or place an extremity into
an area with a radiation dose rate greater than 10 R/hr.
personnel, as well as I&C, were also provided with communications
equipment.
At approximately 4:30 p.m. on March 7, one HP Supervisor, one HP tech
and two I&C techs entered Unit 2 containment to try and push the
cable and detector back through the transfer tube into the Seal Table
Room using long-handled pliers and extensions.
At about 5:00 p.m~,
the I&C techs succeeded in pushing approximately 3 inches of cable*
back into the transfer tube.
At that point the "withdrawn" limit
- switch was noted to be activated in the control room which gave the
licensee some indication as to.the approximate location the detector
had been in during the period of time when the high radiation levels
were noted.
It was also noted at that time that the drive box
appeared to be engaged or reconnected but that just one bolt was
holding it in place. It was decided not to attempt to move the cable
and detecto~ using the drive box because it could not be determined
" .
7
at that time whether or not the cable would slip or be drawn. back-
through the drive box by the tension on the uptake reel holding the
rest of the cable.
Further attempts to push more cable through the
drive box were not successful and the entry was terminated.
Following the entry a debriefing was held to discuss the situation
and plan further action.
The I&C techs stated that it would not be
feasibl~ to push the cable back through the transfer tube because the
tube was too flexible and could not be held in the proper position to
allow insertion of the cable.
It was decided to fabricate a
long-handled device with a bolt attached to the end in ord.er to
secure the drive box together and ensure that it was reconnected.
Then the cable could be driven to storage and the recovery completed.
About 360 mi 11 i rem (mr) had been received by the personnel
participating in this first recovery evolution.
On March 8, 1988, a second entry was* made to recover from the
detector event.
The drive box was reconnected using the long-handled
bolt device and the detector and cable run into the Seal Table Room.
Because the radiation levels had dropped significantly from those_
initially noted, it had been decided to make a survey of the the
detector and cable -to try and determine what the contact readings
were.
The radiation survey showe9 that approximately 6 feet of cable
had been irradiated.
At that point in time, five days after the
initia:l cable withdrawal and exposure event, the detector read 200 *
R/hr and the next 4 feet of adjacent cable read from 35-40 R/hr.
The
next 2 feet of cable read from 4-10 R/hr followed by a rapid decrease
in the radiation levels to approximately 600 mr/hr from that point
along the cable to the 5-path rotary transfer box.
Following the
survey, the detector was driven into the storage port, the cable cut
off and the entry terminated.
Sirice there was still some confusion and concern about the actual
length of the cable that had been activated during the time it was
located in the core and some questions about the relative.positions
of the three individuals who had performed the original work, another
entry ~was made to measure th-e various-*di stances in question.
The
inspector accompanted the team on th{s entry.
These measurements
were subsequently used in further evaluations of the doses received
to estimate the length of the line source and to estimate the length
of cable that was pulled p.ast the crane wall (bioshield) .and into the
drive unit work area.
d.
Review of the Exposure Event
(1)
10 CFR 20.20l(b) requires each licensee to make or cause to be
made such surveys as 1) may be necessary for the licensee to
comply with the regulations in this part and 2) are reasonable
under the circumstances to evaluate the extent of radiation
hazards that may be present.
10 CFR 20.20l(a). defines a
11survey
11 as an evaluation of the radiation hazards incident to
i
" .
..
8
the production, use, release, disposal or presence of
radi cacti ve materi a 1 s or other sources of radiation under a
specific set of conditions.
After questioning of the licensee by the inspector, the licensee
reviewed the location of the detector in the reactor and the
length of time the detector had been in the reactor.
The
licensee determined that the detector had apparently been
inserted in the wrong guide tube due to a misalignment of the
10-path transfer rotary device.
During the flux mapping on
February 8, 1988, when the
11A
11 incore detector became lodged in
the guide tube, the detector was supposedly inserted into the
. 0-10 guide tube.
When it was noted that.the detector was stuck,
it was decided to terminate further mapping attempts because a_
sufficient number *of guide tubes had a 1 ready been mapped and no
further data were needed at that time.
I&C was notified that
the
11A
11 incore detector was stuck and that it would need to be
repaired prior to the next flux mapping effort.
Following the
exposure event and upon analyzing the final flux map taken on
February 8, the licensee determined that the
11A
11 incore detector
had apparently been inserted into the J-5 guide *tube due to the
aforementioned misalignment of the 10-path transfer rotary
device.
The fact that the detector had been inserted into the
wrong guide tube.was not known by th~ perionnel who planned the
initial entry and they therefore did not evaluate the
radiological hazards associated with the irradiated detector and
cable.
In discussions with licensee representatives and through reviews
of records, the inspector determined that the job of freeing a
stuck detector had been performed several times in the past. It
was noted that the detector had typically read between 5 and 35
R/hr while the cable had never been noted to have read anything
above background.
Based on previous experiencet no extra
precautions or further evaluations of the potential problems of
freeing the detector were considered or discussed by the
1 icensee prior to plann-ing. and pe-rform:i-ng the work on March 3,
1988.
-
Failure to adequately evaluate the radiation hazards incident to
removing a detector and a portion of the drive cable which-had
been lodged in the reactor core while at.power was identified as
an*. apparent
violation
of
(50-280,
281/88-10-01).
(2)
10 CFR 19.12 requires that all individuals working in a
restricted area be kept informed of the storage, .transfer, or
use of radioactive materials or of radiation in such portions of
the restricted area and be instructed in the health protection
problems associated with exposure to such radioactive materials
9
or radiation, and in precautions or procedures to minimize
exposure ..
The inspector reviewed in detail the documentation of the
briefing given to the I&C technicians who were to perform the
work of freeing the stuck detector and discussed the contents of
the briefing with those personnel involved iri giving and
receiving the briefing.
All personnel involved indicated that
the steps of the procedure describing the work of freein~ the
detector and repl-acing the detector and cable were reviewed but
that no indication was given that radiation levels would be any
higher than usual.
Along with the procedure review, ~uch items.
as pre-job preparations, tool control, changing gl aves after
handling the highly contaminated cable, keeping exposures as low
as reasonably achievable (ALARA), working safely and maintaining
good communications were also discussed.
The individuals also
indicated that, due to past experience with freeing stuck
detectors and the radiation levels noted during those
operations, no discussion was held concerning the potentiar for
extremely high radiation fields or precautions that should be
taken in such circumstances.
The inspector also interviewed thos~ responsible for planning
and authorizing the detector replacement.
It was noted that
none of these individuals knew of or were made aware of the fact
that the detector and associated cable were lodged in the core
and that the result would be the activation of the cable as well
as the detector.
Everyone involved in planning and authorizing
the work on the detector believed that the job would be similar
to those performed in the past and that no further precautions
were therefore required.
(3) Technical Specification 6.4.A requires that* detailed written.
procedures with appropriate check-off lists and instructions be
provided for preventive or corrective maintenance operations
which would have an effect on the safety of the reactor.
Technical Specification 6.4.B re-quires that radiation control
procedures be provided and that the station radiation protection
program be organized to meet the requirements of 10 CFR 20.
Technical Specification 6.4.E requires that temporary changes to
procedures described in 6.4.A and *s which do not change the
intent of the original procedure may be made, provided that such
changes are approved prior to implementation by a designated
person based on the type of procedure to be c.hanged.
Technical Specification 6.4.F requires that temporary changes to
ptocedures described in 6.4.A and B which change the intent of
the original procedures may be made, provided such c.hanges are
-.-. --~
"
10
approved prior to implementation by a designated person based on
the type of procedure to be changed.
10 CFR 20.206 requires licensees to provide instructions to
individuals working in or frequenting any portion of a
restricted area as specified in 10 CFR 19.12. _
10 CFR 19.12 requires that all individuals working in a
restricted area be-kept informed of the storage, transfer, or
use of radioactive materials or of radiation in such portions of
the restricted area and be instructed in the health protection
problems associated with exposure to such radioactive materials
- or radiation, and in precautions or procedures to minimize
exposure.
(a) Maintenance Procedure IMP-C-IFM-20, Replacing Incore Flux
Mapping Detector, dated August 27, 1987, was used as the
basis for the job of freeing the stuck incore detector.
Because it did not contain steps to perform this work; the
lice'nsee wrote a temporary change to the procedure to cover
this.evolution. It was decided that the added work did not
change the intent of the procedure so the change was made.
- in accordance with Technical Specification 6.4.E and
licensee Admi ni strati ve Procedure SUADM-ADM-21, Sta ti on
Procedures, dated January 26, 1988.
Administrative
Procedure SUADM-ADM-21 states* that any change or deviatioD
to the
11Purpose
11 section of a procedure is defined as
changing the intent. Although no written change was made
to the purpose section in the procedure, the scope or
purpose of the procedure was actually changed by adding
instructions to free the stuck detector, which was not
addressed in the original procedure. Because it did change
the intent -of the procedure, the 1 icensee should have
complied with the more stringent requirements of Technical
Specification 6.4.F by sending the procedure change to the
Station Safety and Operating Committee (SNSOC) prior to
implementation. -
The change, as it was originally written and approved on--=----
March 3, 1988, directed the I&C techs to remove the top and
1 eft side cove.rs of the i ncore drive unit, remove the *
screws holding the drive box together and free up the stuck
-detector.
Once the detector had been dislodged, the drive
cable was to be properly meshed with the drive box, the
drive box reassembled and the detector driven to the proper
storage location by those in the control room.
The change
did not include any *precautions conc~rning assessment of
the
detector
1 s
location
in
the
core
nor
_
i rradi ati on/activation analyses to predict possible hi_gh
radiation levels that might be expected on the incore
detector. It also did not contain any limitations such as
" *
(b)
11
stopping work if a maximum radiation level were exceeded or
reevaluating the job if the detector could not be retracted
using the drive unit as specified. The change allowed the
technicians to free the detector and then engage the drive
unit to complete the withdrawal; it .did not have provisions
or steps which allowed them to continue to pull the
detector into the Seal Table Room and to the limit switch
located near the crane wall.
The individual who wrote the change to the procedure stated
that he had referred to changes that had been written in
the past and had used.the same steps as in the previous
changes.
Because he was not aware of any special problems
or unusual
circumstances, no other precautions -or
instructions were added.
He indicated that, even though
there were only four steps incorporated into the procedure
to guide the workers in how to free *the detector, the
nature of the task did not require any more direction.
Failure to properly classify the change to the procedure as
a change in intent and to provide a written procedure which
addressed such considerations as assessment of detector
position, *, rradi ati on/activation analyses, precautions
concerning high radiation levels and limitations on the job
for freeing the stuck detector was i den ti fi ed as an
apparent violation of Technical Specification 6.4 (50-280,
281/88-10-02).
.
.
While reviewing the documentation for the briefing given to
the I&C techs_ in preparation for dislodging the detector,
it was noted that the HP tech assigned to cover the job had
not attended.
Health Physics Radiation Protection Manual,
Section 2, Part 1,* Radiation Work Permits, dated January
21, 1988, in Step E.2.b requires a Job Foreman/Supervisor
to ensure that the work crew is properly briefed on the
work to be done.
In discussing the fact that the HP tech
did not attend the-briefing_~ with* 1-i censee representatives,
they indicated that this is standard practice.
Briefings
are usually given by the group performing the work and HP
is not involved except in cases where major job evolutions
or other unusual circumstances occur.
The inspector
indicated that containment entries at power to perform work
. are* specfal circumstances .and should . have warranted a
pre-work briefing of all parties involved.
Failure of the Radi.ation Work Permit procedure to require
that all personnel (health physics in this case) involved
in special jobs, such as work performed in containment at
power, be briefed on the work to be performed was
i denti fi ed as another example of an inadequate procedure
12
and an apparent violation of Technical Specification 6.4
(50-280, 281/88-10-03) *.
(4) Technical Specification 6.4.B requires that radiation control
procedures be provided and that the station radiation protection
program be organized to m~et the requirements of 10 CFR 20.
Technical Specification 6.4.D requires that procedures described
in 6.4.A and B be followed.
(a) Health Physics Radiation Protection Manual, Section 2,
Part 1, Radiation Work Permits, dated January 21, 1988,
requires is Step C.2.a that a Special Radiation Work Permit
be used for the performance of a specific work activity in
a specific location or area.
The inspector reviewed the Radiation Work Permit (RWP) used
to cover freeing the detector. The RWP, Number 88-SWP-702,
Minor Maintenance and Inspections Cleared by HP,* dated
January 1, 1988, was found to be .a Standing RWP which could
be* used by anyone entering Unit 2 containment for
routine/minor maintenance or inspections.
All protective
clothing, dosimetry -and radiation monitoring requirements
were noted as
11to be determined
11 by the HP Shift Supervisor
for the specific job to * be . performed.
No* special
precautions or instructions were gjven exce~t thdse
generally found on any generic RWP.
In discussing the RWP with licensee representatives, they
indicated that the job of freeing the stuck detector and
replacing the detector and cable was considered as minor
maintenance and was thus covered by the Standing RWP.
The
licensee also indicated that the use of Standing RWPs for
such tasks was authorized by the RWP Procedure. Step C.l.d
of the RWP Procedure a 11 ows perfo.rmance of a specific
maintenance task under a current Standing RWP provided it
is authorized by an HP Shift-Supervisor.
An interview with
the HP Shi ft Supervisor who authorized the use of the*
Standing RWP for freeing the stuck detector-. ._i ndi ca tea that,
based on the knowledge he had of the job and the expected
dose rates irrthe work area, he had authorized the work and
the use of the aforementioned Standing RWP for this job and
ass'igned specific requirements for radiological coverage of
the job based on the nature of the work.
The Supervisor
also indicated that, had he known or been made aware of the
fact that the detector and cable were to be withdrawn from
the core region of the reactor, he would have required a
Special RWP to cover the work alon_g with very specific
precautions and monitoring requirements.
.. *
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- (b)
Health Physics Procedure HP-3.1.3, Personnel Dosimetry -
Dosimetry Issue and Dose Determination, dated December 8,
1986, requires in Step 4.13.1.3.c that* no person, who has
been working in an area where the non-uniformity of the
radiation total fields meets the criteria for the use of
special dosimetry and special dosimetry was not worn, is to
be allowed entry into the Restricted Controlled.Area (RCA)
until the form HP-14 is completed and the calculated dose
is recorded.
Step 4. 7. 3 .1 requires the licensee to
evaluate the need for multiple whole body badges when the
dose rate to any portion of the whole body (head to thigh)
exceeds* the dose rate at the normal dosimetry location
(upper frontal torso) by a factor of 1.5 and the dose rate
to any portion of the whole body exceeds 100 millirem per
hour.
Step 4.7.3.2 requires the licensee to evaluate the
need for extremity badges when the expected exposure to *the
hands and forearms or feet and ankles is equal *to or
greater than 1 Rem per hour (R/hr) and the extremity to
whole body dose (12 inches from the contact dose rate)
ratio is 5:1 or greater.
On March 5, 1988, the inspector asked for the licensee's
estimates of the whole body exposure received by each of
the individuals involved in the incore detector event. The
licensee indicated that *the doses recorded on. the
individuals' TLDs were* considered to be representative of
the dose each received and, therefore, no further dose
estimates or calculations w~re necessary.
When asked about
estimated extremity exposures, the licensee stated that,.
based on initial calculations of source strength, these
would not be necessary either. Later in the week, a
corporate health physicist was asked by station management
to come to the station and assist in calculating possible
extremity doses from what was thought to be a point source.
As more data were acquired as to the actual nature of the
source term, the inspector again asked.for the l.icensee's
estimates of whole-body expqsure and extr_emity exposure for
each of the people involved.**
From calculations made by the licensee's engineering group,
it was determined that a si*gnificant -portion. of the
radiation detected during the exposure event was
- - attri bu tab 1 e to the activated components .of the cab 1 e; the
detector played a relatively insignificant role during the
initial 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> following withdrawal of the detector and
cable from the core region. Activation analyses were still
being performed by the licensee, however, initial
indications showed that the detector may have had a
radiation level of approximately 5,000 R/hr and the cable
50,000. R/hr.
The licensee indicated that these were very
14
conservative estimates and that actual levels would
pr9bably be well below these figures.
Once this was known, it was *determined that the source term
was the activated cable, a line source, not the detector as
had originally been assumed. * Due to the complex nature of
- the source term in this event, the licensee indicated that
it would be several *days before any initial estimates could
be made.
It was noted that the estimates would need to be
based on the continually changing position of a line source
with respect to the time the workers were in its vicinity,
their respective distances from the source and the limited
shielding provided by the various objects in the work area.
On March 9, 1988, the inspector noted that the three
individuals who had performed the work on the detector were
sti 11 wearing their company-issued TLDs.
The inspector
inquired as to why these people had not been restricted
The * l i censee indicated that,
because of the initial assumption concerning the. adequacy
of their whole body and extremity exposures, the
individuals had been allowed to retain their JLDs and have
. access to the RCA.
Failure of t~e licensee to restrict the three individuals
involved in the detector exposure event from entering the
RCA until an evaluation of their radiation dose was
complete was identified as example of an apparent violation
of Technical Specification 6.4.D (50-280, 281/88-10-03).
(5)
Exposure Assessment
Due to the nature of the source term and the continuing
investigation of the incore detector event 9 the licensee did not
have a final estimate of exposure for the three individuals at
the time of the exits on March 11 and March 25, 1988.
A
corporate hea 1th phys-i-ci st i ndi-eated that the activation
analyses and dose assessments we~e still* under review and would
be in the report to--=oe***is~ued by the investigation teain.
Because no results were ava*ilable for review~ the inspector
informed the licensee *that the issue of whole body and extremity
exposure evaluation and dose assignment would be identified as
an -unresolved item pending NRC review (50-280, 281/88-10-04) *
INCORE DETECTOR MAINTENANCE
RADIATION EXPOSURE EVENT
!
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SURRY UNIT NO~ 2
MARCH 3, 1988
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I OBJECTIVE OF PRESENTATION I
' * -Provide a Brief Overview of the Event
- Provide the Scope, Schedule, and Current Status of
the Investigation
- Provide Preliminary Results of Radiation Dose
Assessment
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I OVERVIEW OF EVENT I
2-8-88 . * "A" lncore Detector Stuck
3-3-88
- Containment Entry to Free and Replace Detector
(Two Instrument Technicians and One Health *
Physics Technician)
- * Detector Manually Withdrawn When Attempt To
Electrically Drive Failed
- Work Terminated By HP When High Radiation
- .
Levels Were Detected
3-8-88 * * ; Subsequ~nt Evaluations ldentif ied The Primary
1 Source of Radiation To Be Activated Cable
3-9-88
- Recovery Actions Completed
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3-11-88 * Investigation Team Appointed
HEALTH PHYSICS
SPECIALIST
( 1 )
DR. B. BARTLETT
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W. L. STEWART
MANAGER
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SUSAN BARNUM
~E~~; ------------- ---------------1 SECY/RECORDER 1 ,
HEAL TH PHYSICS
- ENGINEERING
CONSULTANT
LICENSING
INDUSTRY/IN PO
HUMAN
MOCK-UPa
INTERFACE
PERFORMANCE
EQUIPtv'ENT
EVALUATION
EVALUATION
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, ( 2)
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( 1 )
( 1 )
( 1 )
(3)
DR.CHABOT
R:>NTHOMAS
..DEHEGNER
TOMSHAUB
PATPATTERSON
VVESTINGHOUSE
BILL SAUNDERS
AUDIONISUAL
MEDICAL
QUALilY
PUBLIC
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PRESE;NTATIONS
EVALUATION
ASSlJW\\ICE
INFORMATION
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( 1)
( 1 )
( 1 )
TOMSWEENEY
DR. DINGLEDINE
B.BELONGIA
J.MCDONALD
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I SCOPE OF INVESTIGATION I
Task.
1. Document Sequence of Events
2. Document Cause of Stuck Detector
3. Build Moc~~up and Videotape Reenactment
4. Finalize Radiation Dose Calculation
. 5. Evaluate Se:quence of .Events/Controlling
Procedures and. Determi*ne Corrective Action
6. Review Industry Occurences/Release
Information to Industry
7. Prepare Final Investigation Report .
Scheduled.
Completion
Date
3/22/88 *
3/25/88
3/30/88
3/31/88
3/31/88
4/08/88
4/08/88
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I CURRENT STATUS OF INVESTIGATION~
e Interviews Have Been Conducted and Recorded
- * Preliminary Sequence of Events Has Been Documented
11 Preliminary DQse Calculations Have Been Completed
- to Determine Maximum Dose
- Refine'd Dose Calculations In Progress
- Preliminary Assessment Has Been Made of the
Cause of the Stuck Detector
- INPO Network Entry Made
- Mo~k-up Constructed and Reenactment Videotaped* ;
Editing and Narration in Progress
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. I RADIATION DOSE ASSESSMENT I
Initial Dose Assessments
- Whole Body Based on TLD
.* Extre.1J1ity Based on Survey and Source Decay
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- No Quarterly Limits Exceeded
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1 RADIATION DOSE ASSESSMENT 1 *
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Current Dose Estimate
- Whole Body Adjusted for Proximity to Source
- . Extremity Calculation Based on Conservative
Line Source Model
- ~o Quarterly Limits Exceeded .
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CURRENT DOSE ESTIMATE
Whole Body Doses (above knee)*
- 800 * 1600 mrem
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- : Extremity Doses (lower leg)
820 ~ 1600- mrem
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- Hand Dose at wire
- * about 800 mrem
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I RADIATION DOSE ASSESSMENT I
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- Final *Dose Calculation
- Based on Mock-up Time and Position Study
- * Non-uniformity of Source C*onsidered
- Survey and TLD Data Related to Radiation Source
- Final Dose Expected To Be Lower Than Current
Dose Estimate :: * : ;,
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