IR 05000456/1993019
| ML20045H324 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 07/14/1993 |
| From: | Michael Kunowski, Mccormickbarge, Paul R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20045H306 | List: |
| References | |
| 50-456-93-19, 50-457-93-19, NUDOCS 9307200086 | |
| Download: ML20045H324 (9) | |
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U.S. NUCLEAR REGULATORY COMMISSION
REGION III
u Reports No. 50-456/93019(DRSS); 50-457/93019(DRSS)
Dockets No. 50-456; 50-457 Licenses No. NPF-72; NPF-77 l
Licensee:
Commonwealth Edison Company Executive Towers West III i
1400 Opus Place, Suite 300 Downers Grove, IL 60515 Facility Name:
Braidwood Station, Units 1 and 2 Inspection At:
Braidwood Site, Braidwood, Illinois Inspection Conducted:
May 24 - June 25, 1993 Inspectors: /)lb lLmi l fY /$f)
M. Kunowski
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R. Paul V
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M [4 /ff3 Approved By:
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1-'W'.'McCormick-Harger,fActing ChieT Date f/
Radiological Controls Erection 1 Inspection Sumrnry Inspection on May 24 - June 25. 1993 (Reports No. 50-456/93019(DRSS):
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50-457/93019(DRSS))
Areas Inspected:
Routine, announced inspection of the licensee's radiation protection and radioactive waste (Inspection Procedures (IPs) 83750 and 84750), including audits and appraisals, external exposure controls during two recent refueling outages, calibration and maintenance of effluent radiation monitors, and control room emergency ventilation.
In addition, a special inspection was conducted to review the impact of a recent Unit 2 fuel leak on inplant dose rates and offsite effluents.
flesults:
No violations were identified. Overall, external exposure controls
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during the recent Cycle 3 refueling outages for Units 1 and 2 were good.
The
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higher than planned total dose for the Unit 2 outage was attributed to higher than expected dose rates for a. steam generator modification, to a relatively inexperienced scaffolding work crew, and to maintenance on the reactor coolant loop resistance temperature detector (RTD) system.
Excellent planning and-
. implementation, which resulted in dose savings, were noted for cleaning of the reactor vessel flange and removal and reinstallation of the reactor vessel level instrumentation system.
Regarding the fuel leak, inplant dose rates 9307200086 930714 PDR ADOCK 0500
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increased, but adequate compensatory actions were taken. No impact was seen on the quantity of radioactive material in liquid effluents,' but the amount of noble gas released via the two plant stacks and present in the Unit 2 containment has increased significantly.
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DETAILS 1.
Persons Contacted M. Auer, Electrical Group Lead, System Engineering
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- D. Cooper, Operations Manager
- J. Groth, Maintenance Superintendent
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- A. Haeger, Regulatory Assurance Supervisor
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- J.
Kinsella, Site Quality Verification
- R. Koback, Lead Health Physicist, Operations Group
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- F. Lesage, Site Quality Verification
- J. Lewand, Regulatory Assurance i
R. Owen, Auxiliary Systems Group Lead, System Engineering
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- E. Roche, Health Physics Services Supervisor
- R. L. Thacker, Lead Health Physicist, Technical Group
- C, Brown, Resident Inspector, NRC
- J. McCormick-Barger, Acting Chief, Radiological Controls Section 1, NRC Denotes those attending the exit meeting on June 25, 1993.
The inspectors also interviewed other plant personnel.
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2.
Licensee Action on Previous Inspection Findinas-LClosed) Inspection Follow-up Item (IFI) No. 50-456/92012-Ol(DRSS):
50-457/92012-Ol(DRSS): The inspector will review progress on a modification to the waste gas decay tank (WGDT) radiation monitor (0PR02J). The modification was completed and the previous recurrent inoperability problem because of water intrusion was corrected.
The new monitor determines activity of the waste gas with a detector attached to the outside of the WGDT vent header; the previous monitor determined activity of a sample of the gas.
(Closed) 10 CFR Part 21. Erroneous Air Flow Rate Readinas in Eberline AMS-3 Air Samplers:
Kits from the vendor to correct the potential problem with erroneous air flow rate readings were received and installed by the licensee.
(Closed) Violation No. 50-456/93007-03(DRSS):
No. 50-457/93007-03(DRSSH:
Failure to follow station procedure for posting a contaminated area. The area was posted as required and station personnel were reminded of the requirement.
No similar problems were seen by the inspectors during the current inspection.
No violations of NRC requirements were identified.
3.
Audits and Appraisals (IPs 83750 and 84750_1
The inspectors reviewed field monitoring reports (FMRs).hich record the.
results of quality assurance surveillances of field activit'es and noted
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that the FMRs included a representative sample of typical radiation protection activities. A comprehensive, performance-based audit of the radiation protection program (Audit No. 20-93-11). conducted by an i
offsite team was also reviewed. This audit appeared _ thorough and examined work practices and performance during outage activities,
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radiation work permits, radiation surveys, training, liquid and gaseous effluent activities, and procedure adequacy, implementation, and i
adherence.
With the exception of two findings (incorrect information in the semi-annual effluent report and unauthorized work) and an unresolved
item (inadequate guidance for completing the semi-annual report), the audit found the station had implemented an effective radiation protection program.
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In addition, the inspectors reviewed the results of a licensee review of the scope of its FMR program.
During a previous inspection (Reports No. 50-456/93002(DRSS); 50-457/93002(DRSS)), the inspector raised a question about the need to review more activities related to technical aspects of the bioassay, respiratory protection, and ALARA (as-low-as-reasonably-achievable) programs. The licensee's review indicated that the scope was adequate. This appeared reasonable to the inspectors.
No violations of NRC requirements were identified.
4.
Refuelino Outaae Exposure Control The inspectors reviewed the licensee's post-outage RP summary reports of c
the recent 3rd cycle refueling outage for Units 1 and 2.
Overall, the Unit I report was a detailed and candid document; the Unit 2 report was in draft at the time of inspection. Observations of radiation protection activities during the outages were made by resident and regional inspectors and documented in previous inspection reports.
The Unit 1 outage (AIR 03) occurred from September 5 to November 3, 1992, i
ending seven days ahead of the scheduled 66 days.
Major work included the installation of 369 plugs in 174 tubes and the replacement of 21 Inconel 600 plugs with Inconel 690 plugs (in accordance with NRC Bulletin 89-01). Total outage dose was 185.7 person-rem (1.857 person-sieverts) compared to a goal of 208.5 person-rem (2.085 person-sieverts) and there were 88 personnel contamination events.
Overall, radiological controls were well planned and implemented.
This was the first outage that used an electronic dosimeter (ED) and computer-based access control system for allowing
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entry into the radiologically controlled areas (RCAs), replacing the use of self-reading dosimeters and dose cards.
In addition, new effective practices were implemented for controlling the use of contaminated tools, for the initial staging of sea-vans of equipment in containment, j
and designating (with green flashing lights) low dose areas in containment and the curved wall area. On the other hand, higher than expected dose rates and planning or implementation problems cnntributed to several jobs exceeding pre-job estimates, including reactor vessel level system (RVLS) disconnection and reconnection and reactor vessel flange cleaning.
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i The Unit 2 outage (A2R03) ran from March 5 to May 2, 1993, ending two days ahead of the scheduled 60 days. Major work included a modification of steam generator level indication.
Unlike those in Unit 1, steam generator tubes in Unit 2 required minimal work:
16 tubes were plugged and 2 Inconel 600 mechanical plugs from one tube were removed.
Total dose for the outage was 234 person-rem (2.34 per'on-sieverts) compared s
to a goal of 211 person-rem (2.11 person-sieverts) and there were 119 personnel contamination events. Overall, radiological controls were well planned and implemented.
Using lessons-learned from the previous Unit 1 outage, significant improvements in planning and execution were made in RVLS work and vessel flange cleaning.
Specifically, for the flange cleaning, the licensee had most of the work performed by a-diver with the cavity flooded as opposed to using a crew of laborers in a dry cavity.
This new method resulted in approximately 0.3 person-rem
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(3 person-millisieverts) compared to the 3-4 person-rem (30-40 person-millisieverts) incurred using the old method.
For future flange cleaning, the licensee wrote a detailed job planning document and videotaped the dive.
Notable dose savings were also seen for snubber inspection and testing (488 snubbers were examined and 68 tested).
The savings resulted from overall good planning, location of the snubber testing equipment within the containment RCA, and the use of a dedicated RP technician.
On the negative side, higher than expected dose rates associated with the steam generators (Inspection Reports No. 50-456/93007(DRSS); 50-457/93007(DRSS)), an inexperienced scaffold construction crew, and electrical and mechanical maintenance work on the reactor coolant loop RTD system contributed to the outage dose exceeding the goal.
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No violations of NRC requirements were identified.
5.
Unit 2 Fuel Leak (IPs 83750. 84750)
As discussed in Inspection Reports No. 50-456/93012(DRP);
50-457/93012(DRP), a fuel cladding leak developed in Unit 2 in mid-May 1993.
The leak, first detected with the gross failed fuel monitor (2RE-PR006), and later confirmed with gamma spectroscopic analysis of reactor coolant samples, resulted in increased dose rates in certain areas of the plant, increased noble gas levels in containment, and increased noble gas released from the station's two stacks. Dose equivalent iodine (DEI) levels in the coolant and the dose from effluents were below regulatory limits.
The del peaked at 0.548 microcuries/ gram on May 18,1993 (technical specification limit of 1 microcurie / gram), and by early July was about 0.06 microcuries/ gram.
Low levels of neptunium-239 and cesium-134, -137, indicative of fuel
" wash-out," have also been detected. The increased plant dose rates and noble gas levels are discussed below.
a.
Innlant Dose Rates Since mid-May, the licensee was tracking dose rates in 15 areas in the auxiliary building, including the chemical drain tank room, the gas WGDT cubicle, and the volume control tank (VCT) valve
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aisle. Dose rates in these areas were identified as having changed noticeably as DEI changed. As part of compensatory l
actions, the RP staff worked with the operations and maintenance groups to reduce, reschedule, or eliminate certain work activities in some of these areas, and 4 video cameras were installed to allow operators to complete rounds without entering certain other areas.
These efforts were ongoing at the end of the inspection and were adequate. The inspectors conducted. independent dose rate measurements in several of the 15 areas. The only discrepancy with licensee data was in the chemical drain tank room where the inspectors identified contact dose rates on the bottom of the tank significantly greater than 200 millirem (2 millisieverts (mSv))
per hour in the licensee's most recent survey. A subsequent licensee survey in response to the inspectors' finding identified a localized spot on the bottom of the tank reading 38 rem (0.38 Sv) per hour.
Discussions with the licensee indicated that the likely source was primary coolant discharged from the high radiation sampling system (HRSS) as part of the increased sampling for DEI determination. Although RP personnel had correctly expected dose rates in the tank to increase because of the sampling, the magnitude of the increase was not expected.
Subsequently, DEI sampling discharges were routed to the holdup tank, which not only reduced transient dose rates in the chemical drain tank, but also reduced the amount of noble gas released from the plant stacks. Noble gas from the coolant in the holdup is sent to the WGDT for decay, whereas noble gas from the chemical drain tank is not sent to the WGDT prior to release out the stacks.
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Containment Noble Gas
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Activity increased from a normal level of 5 times the 10 CFR 20 maximum permissible concentration (5 MPCs) to approximately 183 MPCs.
Increased management oversight of Unit 2 containment entries was instituted and information was solicited from other utilities who had experienced similar containment noble gas levels. One problem noted by the inspectors was for an entry on backshift made by the only RP technician onsite.
He was subsequently precluded from all but emergency response to non-RCAs
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areas because noble gas was retained in his lungs about five hours after the entry, much lenger than anticipated by RP personnel.
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In addition, corporate personnel were reviewing the need to j
correct thermoluminescent dosimeter readings for the low energy beta radiation of Xe-133. This correction may be necessary for entries of long duration where skin dose may reach the 10 CFR 20 limit for monitoring.
This will be reviewed during a future-l inspection.
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Noble Gas in Gaseous Effluents With the increase in noble gas because of the fuel leak, the quantity of noble gas released via the plant stacks also-increased.
Some of the increase was from routine Unit 2 containment purges made for pressure relief, but most of the increase was from continuous inputs to the auxiliary building ventilation exhaust system. This increase highlighted the licensee's ongoing " curie reduction program" (Inspection Reports No. 50-456/92012(DRSS); 50-457/92012(DRSS)), which was evaluating various inputs to station gaseous effluents to identify those that could be reduced or eliminated. The program-identified various individual leaky valves, WGDT system leaks, and the use of contaminated sample containers for collecting and analyzing stack releases (which possibly resulted in an overestimate of activity released from the station). Most of these problems have been corrected.
Notwithstanding the success of the curie reduction program, over 800 curies (29.6 terabecquerels (TBq)) of noble gas were released in the first six months of 1993, compared to approximately 233 curies (Ci) for all of 1992.
During the review of the gaseous effluent data, the inspectors noted relatively wide variation in the quantity of noble gas and tritium released since 1991. A table showing this information is given below.
NOBl.E GAS TRITIUM (Ci (TBq))
(Ci (TBq))
1993*
1122 (41)
(1.4)
1992 233 (8.6)
272 (10)
1991 10531 (390)
(3.6)
1990 2445 (90)
(3.2)
1989 1680 (62)
(0.5)
- as of early July 1993 Whereas much of noble gas released in 1991 was attributed to valve leakage (Inspection Reports No. 50-456/92019(DRSS);
50-457/92019(DRSS)), and much of the 1993 release to valve leakage (exacerbated by the fuel leak), the 1992 noble gas value appeared anomalously low while the tritium appeared high.
Further confounding an understanding by the inspectors of release data was
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uncertainty about the effect of a recent change by the licensee in the lower limit of detection for noble gas and the use of the contaminated noble gas sample containers. This matter will be
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reviewed in a future inspection (IFI No. 50-456/93019-01(DRSS);
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50-457/93019-01(DRSS)). The inspectors noted that calculated offsite doses from gaseous releases at Braidwood have been well
below regulatory limits since 1989.
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No violations of NRC requirements were identified.
6.
Liauid Radioactive-Waste (IP 84750)
The inspectors reviewed the licensee's liquid radioactive effluent
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program including information concerning: waste sampling, process and effluent release paths, verification of adequate tank liquid discharge tank mixing, batch releases, and procedures for waste and effluent streams.
The program was reviewed for calendar year 1992 and 1993 to date; no significant problems were identified.
Review of the semiannual effluent reports for 1992 indicated no instances of a release exceeding regulatory limits. There were no abnormal liquid releases during this period.
No violations of NRC requirements were identified.
7.
f.ffluent Control Instrumentation (IP 84750)
The inspectors selectively reviewed calibration and channel functional test records, procedures, and selected setpoint records for effluent radiation monitors and inspected several monitors in the plant.
It appearea that the calibrations and functional tests were performed in
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accordance with procedural requirements.
Detectors were initially calibrated using liquid and gaseous radioactivity; subsequent calibrations were performed using secondary solid sources.
Although efforts of a recently formed licensee task force have improved the availability of station area and process monitors (Inspection Reports No. 50-456/93007(DRSS); 50-457/93007(DRSS)), further effort may he necessary for several monitors. The inspectors noted that in 1992 anu 693 to date, the liquid radwaste discharge and station blowdown monitors were inoperable during several liquid radwaste discharges, due to contaminated sample containers. Although replacement of the containers was usually completed within one day, the paperwork process may have added additional days to the period of monitor unavailability.
Discussions with the licensee also indicated a recurrence of problems
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with the containment fuel handling incident area monitors (Inspection Reports No. 50-456/92012(DRSS); 50-457/92012(DRSS)).
The latest problems were identified before failure of the detectors and generation of a containment ventilation isolation signal, unlike the previous probl ems.
Because of apparently similar failures at the Byron station, the licensee is evaluating the possibility of a generic problem with these detectors as used in containment.
The inspectors will review resolution of the problems with the liquid release and fuel handling incidents during a future inspection.
No violations of NRC requirements were identified.
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8.
Air Cleanino Systems (IP 84750)
The inspectors reviewed results of surveillances conducted to satisfy technical specifications 4.7.6.c.1) and 3), and 4.7.6.h. for the control room ventilation system.
No problems were identified during the review.
Measurements of system flow rate and filter and adsorber in-place penetration met the acceptance criteria. Offsite laboratory analyses of charcoal adsorber samples indicated methyl iodide penetration below the specified limit.
The surveillance: were conducted at the required frequency.
No violations of NRC requirements were identified.
9.
Exit Meetina The scope and tentative findings of the inspection were reviewed with licensee representatives (Section 1) at the conclusion of the inspection on June 25, 1993. The licensee did not identify any documents as proprietary. The following matters were specifically discussed by the inspectors:
radiological controls during the recent Unit 2 outage (Section 4),
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efforts of the curie reduction program (Section 5), and e
actions taken in response to the Unit 2 fuel leak (Section 5).
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