IR 05000374/1993025
| ML20058M409 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 09/27/1993 |
| From: | Kozak T, Louden P, Paul R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20058M403 | List: |
| References | |
| 50-374-93-25, NUDOCS 9310050206 | |
| Download: ML20058M409 (8) | |
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U.S. NUCLEAR REGULATORY COMMISSION
REGION III
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Report No. 50-374/93025(DRSS)
Docket No. 50-374 License No. NPF 18
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Licensee: Commonwealth Edison Company Post Office Box 767 Chicago, IL 60690
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Facility Name:
LaSalle County Station, Units 1 and 2 Inspection At:
LaSalle County Station, Marseilles, Illinois Inspection Conducted:
September 8 through 14, 1993 Inspectors:
'ib3/Lfn, 9/>7[f3 Fatricki ' Louden Date /
Radiation Specialist YPe4-dr
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RonaluA. Paul Date
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Senior Radiation Specialist
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Accompanying Personnel:
Charles Phillips, LaSalle Resident Inspector l
Anthony McMurtray, Reactor Engineer
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Approved By:
Ekt1 f)-7[1 Thomas (J. Kozak, Acting Chief Date
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Radiological Controls Section 2 Inspection Summary Inspection on September 8 throuah 14. 1993 (Report No. 50-374/93025(DRSS))
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Areas Inspected:
The scope of this inspection was to review circumstances and
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events surrounding the unplanned intake of radioactive material by several workers while performing work on the Unit 2 reactor vessel head on September
7, 1993.
Results: Three apparent violations of NRC requirements were identified, including:
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(1)
Failure to perform an adequate evaluation of radiological hazards
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incident to workers.
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Failure to use engineering controls to mitigate the creation and subsequent exposure of workers to an airborne radioactivity area.
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(3). Failure to follow radiation protection procedures in accordance with Technical Specifications.
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Several programmatic weaknesses were also identified during the review. A summary of the observed weaknesses are listed below:
Management oversight of in-plant activities was inadequate to ensure that expectations were being met and that work was being accomplished in an acceptable manner.
- The pre-job meeting was ineffective in identifying the nature and scope of the work to all parties.
Poor communications between the radiation protection and mechanical maintenance departments in the meeting contributed to the problem.
- Poor radiation worker and radiation protection technician performance during the disassembly.
- Ineffective long term corrective actions which were developed to address continuing radiation worker and radiation protection technician performance problems.
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DETAILS
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Persons Contacted Licensee' staff-
- L. Aldrich, Corporate Health Physics
- J. Atchley, Asst. Superintendent of Operations
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- R. Bare, Senior Quality Controls ; Inspector
- J. Bell, Supervisor, Maintenance Support Staff
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- J. Burns, Regulatory Performance Administrator
- D, Carlson, Station Regulatory Assurance
- M. Cooper, Refuel Floor' Coordinator, Technical Staff
- R. Crawford, Superintendent, Work' Planning
- M. Cray, Master, Instrument Maintenance
- J. Gieseker, Manager, Site. Engineering and Construction
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- W. Kirchhoff Site Engineering Station' Support
- P. Knoll, Contamination Control Coordinator, Radiation Protection
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- K. Kociuba, Master, Electrical Maintenance
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- D. Leggett, Outage Manager
- J. Lockwood, Supervisor, Regulatory Assurance
- J. McIntyre, Superintendent, Station Quality Verification
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- W. Murphy, Site Vice President l
- T. Nauman, Master, Mechanical Maintenance
- L. Oshier, Health Physics Services Supervisor
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- M. Reed, Superintendent, Technical Services
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- M. Santic, Superintendent, Maintenance Department
- C. Sargent, Superintendent, Site Services
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- J. Schmeltz, Superintendent, Operations
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- T.
Shaffer, Administrative Assistant to the Site Vice President
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- J. Terrones, Station Quality Verification Inspector
- D. Trager, Office Supervisor
- M. Tyrell, Acting Radioactive Waste Coordinator
Nuclear Reaulatorv Commission
- W. Axelson, Director, Division of Radiation Safety and
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Safeguards
- R. Hague, Chief, Reactor Projects Branch 1, Section C-i
- W. Snell, Acting Chief, Reactor Support Programs Branch The inspector also interviewed other licensee personnel in various departments in the course of the inspection.
- Indicates those present at the exit meeting on September 14, 1993.
2.
Refuel Floor Event of September 7. 1993
Event Description On September 4,1993, Lasalle County Nuclear Unit 2 was shutdown for a refueling and maintenance outage. As part of the reactor
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vessel head disassembly in preparations for refueling, the reactor
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vessel head studs were detensioned on the midnight shift, on
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September 7, 1993. Air samples taken in the refueling cavity i-during detensioning indicated airborne contamination levels were
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At approximately 0730, a pre-job meeting was held to-discuss the l
next evolution in the vessel disassembly work which was to continue during the day shift. Attendees at the meeting-included Mechanical. Maintenance (MM) crew members, a MM foreman, and the
three Radiation Protection Technicians (RPTs) assigned to the Refuel Floor (RFF) to cover the job.
Several aspects of the job
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were discussed but very little of the discussion entailed radiological control considerations.. The work involved the loosening of 19 reactor head studs and removing all reactor head nuts. The work was to be performed simultaneously by three crews
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using pneumatic tools. The use of-High Efficiency Particulate Air (HEPA) filtration units, exhaust diffusers for the pneumatic
tools, or other engineering control devices was 'not discussed l
during the meeting or specified in radiation work permit (RWP)-
number 93-30680A which covered reactor head disassembly.
The RWP
did specify that respirators were to be worn in areas greater than
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l 100,000 dpm/100cm.
Even though contamination levels exceeded 100,000 dpm/100cm' in some areas of the cavity prior to commencing work, no respirators were worn.
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The first crew entered the cavity at about 0810.
This three man crew was to use a large pneumatic tool to break loose 19 studs.
i The second crew followed about 10 minutes later and was assigned to spin the 19 studs free of the vessel flange (using a smaller pneumatic tool) so they could be removed with the vessel head.
A third crew entered the cavity at about 0830.
Their task was to
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remove the nuts from the remaining-studs-on the vessel head using
a small pneumatic tool similar to that used by the second crew.
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In total, three. crews (eight men) were using'three pneumatic tools
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simultaneously in the cavity. Two RPTs were covering the job at
this stage from the RFF. At no time did the RPTs enter the i
cavity. Two Continuous Air Monitors (CAMS) were functioning on
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the RFF.
However, the nearest CAM was at least fifty feet from i
the reactor cavity. No air sampling of the immediate work area
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was being performed during the work.
l At about 0900 the Operations Department secured the Unit 2 Reactor
Building Ventilation (VR) to perform a scheduled surveillance.
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This procedure had been concurred on by radiation protection.
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At approximately 0915, a third RPT (#3) entered the RFF to relieve
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one of the two RPTs (#2) already on the floor.
RPT #3 immediately went over to a CAM which was being tested for potential use at the i
station.
He attempted to source check the monitor and when several attempts proved unsucces'sful, he proceeded to the RP desk on the RFF. On his way he noticed one of the two CAMS used on the I
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. RFF was in alarm (a small red light).
The RPT looked at the strip chart and noted an increasing trend.
To verify the indicati
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he went over to CAM #2 and, while not yet in alarm, an increas
..g trend was noted on the strip chart. As RPT #3 was preparing to
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set up a local air sample, RPT #2 phoned him from the frisking station one elevation below the RFF to inform him that his face was contaminated. RPT #3 immediately went over to the cavity and informed the MM workers of the condition and ordered them to evacuate the cavity.
At approximately 0940, all the workers had exited the RFF.
The RFF coordinator requested that Operations re-start VR (believing it was a cause of the airborne condition).
Shortly thereafter, contamination was detected in various levels of the Unit 2 reactor building.
Contamination levels varied from 1,000 to 40,000 dpm/100cm (16.67 to 666.67 Bq/100cm') in localized areas
throughout most of the Unit 2 Reactor Building (RB).
The pathway of the air flow was determined to be through gaps in the RFF equipment hatch, which had not been properly sealed, and through the elevator shaft for the Unit 2 RB elevator.
In total, 22 individuals were contaminated due to the event.
All workers were sent for whole body counts after decontamination efforts were completed.
Seventeen of the workers displayed positive whole body counts, the highest being about 1,000 nCi (0.037 MBq).
The highest airborne concentration readings, based on the CAM which alarmed (approximately 75 feet away) was 5.2 MPCs.
An evaluation of the problems with the job was performed by the licensee and the work was completed later the same day with the use of respiratory protection devices, local HEPA filtered ventilation units, and breathing zone air samples.
The inspectors reviewed the station's performance in determining the extent of the contamination and the associated internal exposures of the individuals receiving intakes of radioactive material.
Independent calculations were performed by the inspectors and no problems with the licensee's evaluations were identified.
The whole body count results of three of the workers indicated that their intakes were via both inhalation and ingestion pathways.
All other worker's count results indicated that their intakes were via the ingestion pathway.
The licensee estimated that the worst case dose due to the intakes would be in the range of 50 mrem (500 Sv) and that the maximum calculated exposure to the workers was approximately 50 MPC-hours.
The various areas in the Unit 2 reactor building which were contaminated due to the spread of the airborne radioactivity were decontaminated.
The licensee formed a root cause investigation team to review the event.
Preliminary findings of the team were basically consistent 5 with those of the inspectors.
The investigation was not complete
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at the end of the inspection.
Inspect ion F indings Three apparent violations of NRC requirements were identified with regard to the evaluation and execution of this job.
The inspection findings indicated that radiation protection personnel failed on several opportunities to identify the potential for radiological conditions to change.
Further, radiation protection technician and radiation worker performance during the job was poor in that, although there were clear indications that problems were occurring, the changing radiological conditions were not recognized.
The findings are summarized as follows:
The As-Low-As-Reasonably-Achievable (ALARA) review did not
reference previous experience in performing this job.
P,adiological control precautions used in lieu of respiratory protection during previous outages such as allowing only one crew to operate at a time and the use of a strippable coating which contained contamination on the cavity walls were not considered when evaluating what radiological conditions would be present in the work area.
Without these precautions it is clear, given the contamination levels present in the cavity prior to performing work and the local exhaust of the pneumatic tools, that there was a potential for radiological conditions to change and control measures should have been specified.
The failure to perform an adequate survey to evaluate radiological hazards incident upon workers is an apparent violation of 10 CFR 20.201(b).
(Apparent Violation 50-374/93025-01).
- RWP 93-30680A did not specify the use of engineering controls such as the use of HEPA filtration units or exhaust diffusers for the pneumatic tools.
Clearly, the contamination levels in the work area and on the studs themselves indicated that localized veritilation units, at a minimum, should have been used to limit the spread of contamination.
Failure to use engineering controls to mitigate or limit the creation of an airborne radioactive area is an apparent violation of 10 CFR 20.103(b)(1).
(Apparent Violation 50-374/93025-02).
- RWP 93-30680A stated that radiation protection personnel could waive respiratory requirements if contamination levels in the work area were between 50,000 and 100,000 dpm/100cm".
Survey information prior to the job indicated that some areas within the reactor cavity were greater than 100,000 dpm/100cm' yet the work continued without a review to erisure prescribed protective clothing and other controls were adequate to ensure protection to the workers.
Failure to follow radiation protection procedures is an apparent
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violation of Technical Specifications 6.2.B. which requires, in part, that radiation protection procedures be followed (Apparent Violation 50-374/93025-03).
e The RPIs covering the job did not recognize that radiological conditions were changing in the reactor cavity once the work began.
Due to the inadequate positioning of the CAMS, airborne contamination surveys were not performed in the work area during the job.
Because of this, the airborne problem was not identified until well after it had occurred.
Failure to perform surveys to determine radiological hazards present is another example of an apparent violation of 10 CFR 20.201(b).
- The Operations Department secured the Unit 2 Reactor Building Ventilation (VR) to perform a scheduled surveillance even though lessons learned from previous problems indicated that constant air flow should be maintained on the RFF during work evolutions.
When the ventilation was restarted, several floors of the reactor building were contaminated.
This was due, in part, to j
covers placed over the RFF equipment hatch not being taped as required by RWP 93-30680A.
This is another apparent violation of Technical Specifications 6.2.B.
Several programmatic weaknesses were also identified during the review.
A description of the weaknesses are listed below:
e Management oversight of in-plant activities was inadequate to ensure that expectations were being met and that work was being accomplished in an acceptable manner.
The overall radiological responsibility for the RFF was given to the RPIs covering the job (s).
Only a limited amount of oversight by supervisory personnel and management was provided on the RFF.
- Communications at the pre-job meeting were poor in that the radiation protection technicians did not fully understand the operation of the air tools.
Therefore, they could only speculate on the effect the tools' exhaust would have on the surrounding area.
Poor interdepartmental communications has been a topic of discussion in past NRC Inspection Reports and at an Enforcement Conference held in January 1992.
e The maintenance workers in the cavity saw indications of material moving around the studs, but they did not recognize that their activities were creating an airborne environment.
This is an example of poor radiological worker performance.
Further, the RPTs performance was poor in that they did not recognize that the three pneumatic tool exhausts could be causing an airborne contamination condition.
The NRC has previously identified and discussed radiation worker and RPT
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performance problems with the licensee in a 1991 Management
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Meeting and a 1992 Enforcement Conference.
It does not appear that long-term corrective actions have been l
effective, 8.
Exit Meetina The scope and findings of the inspection were discussed with licensee representatives (Section 1) at the conclusion of the inspection on September 14, 1993.
Licensee representatives did not identify any documents or processes reviewed during the inspection as proprietary.
Specific items discussed at the meeting were as follows:
e The three apparent violations.
Observations by the inspectors and NRC management of the e
additionally observed weaknesses identified during the inspection.
NRC management discussed recent radiological events which appear e
to indicate a declining performance with respect to radiological controls.
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