ML20058H393
| ML20058H393 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 12/06/1993 |
| From: | Michael Kunowski, Louden P, Snell W NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20058H372 | List: |
| References | |
| 50-374-93-34, NUDOCS 9312130067 | |
| Download: ML20058H393 (6) | |
See also: IR 05000374/1993034
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U.S. NUCLEAR REGULATORY COMMISSION
REGION III
Report No. 50-374/93034(DRSS)
Docket No. 50-374
License No. NPF-18
Licensee: Commonwealth Edison Company
Post Office Box 767
Chicago, IL 60690
Facility Name:
LaSalle County Station, Unit 2
Inspection At:
LaSalle County Station, Marseilles, Illinois
Inspection Conducte :
November 2 throu
9, 1993
Inspectors:
A
/R
Patrick L. Louden
Date '
Radiation Specialist
/Y
8. N h
(2/C/fJ
Michael A. Kunowski
Date
Senior Radiation Specialist
Approved By- M
d d/
a A /n
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WiTliam Snell, Chief
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Radiological Programs Section 2
Inspection Summary
Inspection on November 2 throuah 9. 1993 (Report No. 50-374/93034(DRSS))
Areas Inspected:
Special reactive inspection of the circumstances and events
involving the administrative overexposure of a worker while performing post
maintenance valve testing in the Unit 2 reactor water cleanup hold pump room
on October 31, 1993.
Results:
Two violations of NRC requirements were identified. The first
violation involved inadequately placing the reactor water cleanup system out-
of-service (00S) which resulted in the "B"
filter 'demineralizer being
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backwashed while the system was drained, which caused a 90 rem /hr (0.9 Sv/hr)
hot spot in the area in which a worker was standing. 'The second violation was
associated with the inappropriate actions of the worker who, when hearing the
electronic dosimeter _he was wearing alarm, did not immediately leave the area
as directed by.the radiation work permit (RWP) under which he was working.
A
second example of a failure to follow RWP requirements was also identified, in
that, this same worker entered a contaminated area which contained
contamination levels greater than 50,000 dpm/100cm' (833.3 Bq/100cm') wearing
minimal protective clothing (PCs). The RWP did not allow for the wearing of
minimal PCs in contaminated areas greater than 50,000 dpm/100cm (833.3
9312130067 931206
ADOCK 05000374
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Bq/100cm') . This event is a continuing example of the licensee's failure to
recognize the potential for changing radiological conditions and the overall
stationwide lack of respect for the radiation hazards encountered in day-to-
day operations within the plant.
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DETAILS
1.
Persons Contacted
Licensee staff
- J. Arnould, Regulatory Assurance
- J. Atchley, Asst. Superintendent of Operations
- R. Bare, Senior Quality Controls Inspector
- J. Bell, Supervisor, Maintenance Support Staff
- M. Friedmann, Technical Lead Health Physicist
- S. Harmon, Supervisor, Training Department
- R. Haynes, Station Quality Verification
- K. Kociuba, Master Electrician, Electrica1' Maintenance
- J. Lockwood, Supervisor, Regulatory Assurance
- J. McIntyre, Superintendent, Station Quality Verification
- E. McVey, Regulatory Assurance
- L. Oshier, Health Physics Services Supervisor
- R. Ragan, Supervisor,-Systems Engineering
- J. Rodriguez, Senior Radiation Protection Technician
- M. Santic, Superintendent, Maintenance Department
- C. Sargent, Superintendent, Site Services
- J. Schmeltz, Superintendent, Operations
- J. Terrones, Station Quality Verification Inspector
Nuclear Reaulatory Commission
- H. Clayton, Chief, Reactor Projects Branch 1
- C. Pederson, Chief, Reactor Support Programs Branch
- D. Hills, Senior Resident Inspector
- C. Phillips, Resident Inspector
Illinois Deoartment of Nuclear Safety
- J. Roman, Resident Engineer
The inspector also interviewed other licensee personnel in various
departments in the course of the inspection.
- Indicates those present at the exit meeting on November 9, 1993.
2.
Administrative Overexoosure Event of October 31. 1993
On October 31,- 1993, during the evening shift,.two operators (0pl, Op2)
were given their shift duties to perforg post maintenance. valve testing
on several valves associated with the ' Unit 2 Reactor Water Cleanup.
(RWCU) system. They reported to the radiation protection (RP) desk
where survey maps were reviewed with the radiation protection technician
(RPT) at the desk and high radiation area keys were provided for access
to rooms on three elevations of the Unit 2 reactor building. The
operators performed their inspections on the-761' and 807' elevations
and noted alleaking valve which would have to be repaired prior to their
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continuation of work on the 807' and other elevations.
Sometime during
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this part of the shift they where assigned by control room personnel to
backwash the "B" RWCU filter demineralizer.
During the initial phases
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of the backwash, Op1 entered the hold pump room to verify the proper
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cycling of the F0010B valve which actuates during the early stages of
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the backwash process (the F0010B valve is located in the same general
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area where Op2 later entered the room and received the higher dose).
Op1 exited the room and went back to the RWCU control panel to finish
the backwash with Op2.
Following the completion of the backwash, Op2
entered the hold pump room to verify proper cycling of the F0032B valve
(an air operated ball valve). Op1 began the valve cycling via the RWCU
control panel. Op2 heard the solenoid actuate on the valve.
He also
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noticed a whining noise which at the time he attributed to air movement
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associated with the opening of the valve. After the valve had cycled
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open (approximately 30 seconds), Op2 noticed that the whining noise was
continuing and he noticed that the noise was his electronic dosimeter
al arming. Op2 pulled the dosimeter'from his pocket and.saw a reading of
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220 mrem (2.2 mSv) and increasing (while standing in the same area). He
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left the area immediately after seeing the high reading on the'
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dosimeter.
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Op2 reported to RP with his electronic dosimeter in alarm.
The alarm
was indicating both high dose rate and accumulated dose. The RP shift
foreman cleared the dosimeter and dispatched a RPT to the room to
determine the cause of the alarm. Subsequent surveys revealed a 90
rem /hr (0.9 Sv/hr) hot spot in a pipe which was about head-high in the
area where Op2 was standing. The pipe exhibited dose rates from 50 to
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90 rem /hr (0.5 to 0.9 Sv/hr) throughout the length of pipe surveyed.
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Following this event, the RP department examined the historical data
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recorded by the two operators' dosimeters. Op1's dosimeter indicated
the highest dose field encountered to be 140 mrem /hr (1.4 mSv). Op2's
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dosimeter showed the highest dose field encountered to be 5 rem /hr (0.05
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Sv/hr).
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J_nspection Findinos
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The inspectors reviewed the event through interviews with cognizant
individuals involved and observed the RP department's followup time
motion study to ascertain the actual whole body dose received by the
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worker.
Based on reviews of followup radiation surveys, the worker.
sheuld have encountered a dose rate field which would have caused his
dosimeter to alarm well before he arrived at the location of the valve
in which he was to inspect.
Interviews with the worker indicated that
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he could not recall hearing the dosimeter alarming.
The dosimeter was
tested and re-calibrated after the incident and was found to be in' good
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working order.
The inspectors attended the time motion study performed by the RP
department to ascertain the actual whole body dose rate fields the
individual encountered and to determine the actual whole body dose
received. The worker was wearing his dosimeter in his right chest
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pocket. The highest dose rate field registered on the dosimeter was 5
rem /hr (0.05 Sv/hr). Adjusting for the height of the worker and his-
relative position tc the 90 rem /hr (0.9 Sv/hr) source, it was determined
that the worker's head was in a 18 rem /hr (0.18 Sv/hr) dose rate area.
The time-motion studies indicated that the worker's head was in this 18
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rem /hr (0.18 Sv/hr) dose rate field for approximately 2 minutes. The
corrected exposure values based on the time / motion study compared well
with the accumulated dose recorded on the electronic dosimeter for the
dose rate fields the dosimeter was actually within.
Based on the
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adjusted exposure values the worker's corrected exposure for the entry
was recorded as 655 mrem (6.55 mSv), and 699 mrem (6.99 mSv) total
external exposure for the day.
This total was well above the daily
administrative exposure limit of 100 mrem (1 mSv) but under the
regulatory limit of 1,250 mrem / quarter (12.5 mSv/ quarter). The
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inspectors verified that the worker had a current NRC Form 4 on file
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which would have allowed the individual to receive a quarterly
regulatory dose of 3000 mrem (30 mSv) for the quarter. Adding the
adjusted exposure for this event to the worker's previously recorded
quarterly dose gave the individual a quarterly total of 887 mrem (8.8
mSv) for the current quarter.
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Based on further review of the event the inspectors noted the following
contributors /causes to the event:
The RWCU system was not appropriately placed 00S.
When the
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system was placed 00S on or about October 1, 1993, the 00S
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package stated to verify that the system had been shutdown
according to RWCU procedures.
LOP-RT-12, step F.5, states
that all filter demineralizer trains are to be backwashed
prior to removing the entire system from service.
This
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failure to perform the backwash prior to the shutdown of the
system as required was a contributing root cause of the
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creation of the hot spot.
This failure to follow a
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procedure described in Regulatory Guide 1.33, as referenced
in Technical Specification 6.2. A is a violation of the RWCU
system shutdown procedure LOP-RT-12, step F.5. (Violation
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50-374\\93034-01)
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Based on followup surveys, Op2's electronic dosimeter should
have alarmed from a high dose rate several feet before he
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reached the area of the F0032B valve.
The worker should
have responded to the alarming dosimeter by immediately
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leaving the area when hearing the alarm as directed in the
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RWP under which he was working.
(Violation 50-374\\93034-
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02a)
During the investigation following the event, the worker
displayed an attitude of "getting the job done" rather than
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to heed dosimeter alarms.
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The worker was also not appropriately dressed in protective
clothing (PCs) for the entry into the contaminated area
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which contained contamination-levels greater than 50,000
dpm/100cm (833.3 Bq/100cm'). The RWP did not allow the
wearing of minimal PCs for areas with such contamination
levels. (Violation 50-374\\93034-02b)
The backwash procedures did not include any type of
notification to RP to perform followup surveys to ensure
radiological conditions had not changed. However, past
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experience with the system in normal configuration,
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indicated no radiological problems associated with the
backwash.
Two violations of NRC requirements were identified. One weakness with
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respect to identifying the potential for radiological conditions was
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identified.
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8.
Exit Meetina
The scope and findings of the inspection were discussed with licensee
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representatives (Section 1) at the conclusion of the inspection on
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November 9, 1993.
Licensee representatives did not identify any
documents or processes reviewed during the inspection as proprietary.
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Specific items discussed at the meeting were as follows.
The two apparent violations of concern which occurred during the
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event,
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NRC management's concerns with the attitude of radiation workers
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and particularly station management to respect the radiological
hazards encountered in the plant.
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A discussion to the effect that this event would be reviewed for
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the substantial potential for an overexposure.
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