IR 05000263/1998008
| ML20217M344 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 04/30/1998 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| Shared Package | |
| ML20217M332 | List: |
| References | |
| 50-263-98-08, 50-263-98-8, NUDOCS 9805040489 | |
| Download: ML20217M344 (13) | |
Text
i
.
.
U.S. NUCLEAR REGULATORY COMMISSION REGION lli Docket No:
50-263 License No:
' DPR-22 Report No:
50-263/98008(DRS)
Licensee:
Northern States Power Company Facility:
Monticello Nuclear Generating Plant Location:
2807 W. County Road. 75 Monticello, MN 55362 Dates:
April 6 - 9,1998 Inspector:
W. Geoffrey West, Radiation Specialist Approved by:
G. Shear, Chief, Plant Support Branch 2 Division of Reactor Safety
!
i 9805040489 900430 i
PDR ADOCK 05000263
'
G PDR
,
.
.
EXECUTIVE SUMMARY Monticello Nuclear Generating Plant NRC Inspection Report 50-263/98008 This inspection evaluated the licensee's radiation protection (RP) activities during a refueling and maintenance outage. General plant radiological conditions and controls were inspected; radiation worker practices and RP staff support were observed and evaluated; and outage job radiological planning was reviewed. The following conclusions were reached in these areas:
Plant walkdowns revealed that radiation workers were cautious and conscientious of
.
radiological hazards during outage activities. For instanca, workers were careful with donning and doffing of personal contamination clothing (PCS), requested RP assistance for vatious tasks, were knowledgeable of their radiation work permit (RWP)
requirements, and were aware of radiologica! conditions in their work areas (Section R1.1).
RP staff support of plant work was very effective in reducing radiological risks. In
-
particular, the drywell entry RP staff was very active in explaining transit routes and survey results to radiation workers, and the refueling floor RP staff actively enforced good RP practices by workers on the deck (Section R1.1).
Plant housekeeping was effective in maintaining the plant relatively free of unnecessary
.
materials, equipment, and debris (Section R1.1).
The reactor water cleanup flow element installation and pipe replacement job was
.
implemented safely and effectively. Improvements were made from lessons learned in a previous similar evolution and effective methods were used to minimize worker dose.
In addition, an appropriate level of RP coverage was assigned to the job and the as-low-as-is-reasonably-achievable (ALARA) planning was detailed and comprehensive. The l
licensee's decision to include the pipe replacement in the flow element job demonstrated i
a commitment to future worker dose reduction (Section R1.2).
The drywell in-service inspection activities were carefully monitored and controlled by
]
.
!
RP personnel and had been assigned appropriate radiological controls based on the dose rates and risk of contamination involved. The plant continued to see a benefit from depleted zine oxide injection through reduced dose rates in the drywell (Section R1.3).
The ALARA/ job planning for the safety relief valve topworks rebuild and replacement
.
evolution was adequate. Appropriate engineering controls, dosimetry placement, and RP staff visual coverage contributed to the safe and efficient execution of this job.
However, the inspector also noted a lack of RP staff involvement in the mockup training for the workers, as well as the absence of any feedback to the job ALARA planner from the post-job ALARA review (Section R1.4).
I l
.
.
Report Details R1 Radiological Protection and Chemistry (RP&C) Controls l
R1.1 Walkdowns within the Radioloaically Controlled Area (RCA)
a.
Insoection Scooe (IP 83750)
l l
The inspector examined various areas of the RCA, including the reactor building and drywell, turbine building, and radwaste building. During these walkdowns, the inspector
reviewed the following items:
radiation worker practices,
!
.
l radiological posting and labeling,
.
radiation protection staff activities, and e
plant housekeeping.
a The inspector interviewed radiation protection (RP) staff regarding radiological
,
conditions and controls within the plant, and also interviewed various radiation workers l
to assess their knowledge of their radiation work permits, job functions, and radiological conditions and controls in their work areas.
l b.
Observations and Findinas l
The inspector found that radiation workers in the plant were responsive to radiological postings, careful to prevent the unnecessary spread of contamination, and aware of the
radiological conditions in which they were working, as well as the conditions of their
!
radiation work permits (RWPs). One possible contributor to this awareness was the licensee's recent installation of a new computerized RWP sign-on process for workers, l
which clearly and automatically displayed relevant RWP information to workers signing in. The inspector found this system to be both efficient and helpful to radiation workers.
Workers donned and doffed personal contamination clothing (PCS) correctly and requested RP staff assistance in surveying work areas and identifying good transit paths i
in the drywell. The inspector noted a high level of caution and awareness of radiological
!
hazards through interviews with and observations of the outage workforce.
Radiological posting and labeling in the plant was appropriate and effective in informing radiation workers of radiological conditions. For the outage, the drywell was posted as a Locked High Radiation Area (LHRA) and Contaminated Area. Though most of the drywell was usually below the LHRA criterion (greater than 1 rem per hour (R/hr) at 30 cm), these postings were appropriate because of the potential for transient elevated dose rates during the removal of shielding during work as well as the opening and movement of contaminated and/or activated components. Though areas of higher ambient dose rates were not posted in the drywell (they are posted elsewhere in the plant), the inspector observed the drywell RP staff showing workers where these locations were, monitoring worker body positioning, and performing frequent surveys.
Smear tests performed by the inspector verified the accuracy of the licensee's
)
,
i
[
l contaminated area postings on the refueling floor and elsewhere in the reactor building.
i Bags and other containers of radioactive material were also properly labeled and I
secured.
The inspector observed radiation protection staff activities in the plant and found them to be adequate. In particular, the drywell entry point RP staff was very active in explaining transit routes and survey results to entering workers. Also, refueling floor RP staff was proactive in enforcing good RP practices among radiation workers on the deck. The RP staff was frequently observed counseling workers on contamination control, proper anti-contamination dressing, stay times, dosimetry placement, and body positioning.
l However, the inspector identified one instance in which an RP helper did not exercise good contamination control practices in that operators working in the hydraulic control j
unit overhead area threw contaminated PC's down to the individual, who was standing l
outside of the contaminated area..Although the helper wore cotton gloves and the i
contamination levels in the work area were relatively low (about 1,000 disintegrations
per minute (dpm)/100 cm ), this poor practice could have contaminated the helper and spread contamination to individuals or surfaces outside of the posted contamination area. The inspector informed RP management of this observation and they stated that they would counsel the helper to discontinue this practice.
The inspector found that plant housekeeping was effective in maintaining the plant
)
relatively free of unnecessary materials, equipment, and debris. Though outage work demanded a certain amount of material to be present and the establishment of a high number of contaminated area zones, the licensee's staff ensured that clean areas were mopped frequently to reduce the spread of contamination, and appropriate clean walkways were available for employees to transit the plant. The inspector observed a large number of drums and tool carts containing low-level radioactive waste (laundry, tools, etc.) placed in a radiologically controlled area outside the radwaste building (and within the protected area). Though the containers appeared to be in good condition and were closed, the inspector questioned whether the containers, especially the tool carts, were sealed against rain intrusion and potential contamination migration. The RP staff looked into this issue and determined that, because of the structure of the containers, rain intrusion was highly unlikely; however, the radiation protection manager (RPM)
stated that the plant would investigate methods to eliminate any possibility of water intrusion. The inspector agreed with the licensee's conclusions and their proposed course of action.
c.
Conclusions Plant walkdowns revealed that radiation workers were cautious and conscientious of radiological hazards during outage activities. For instance, workers were careful with donning and doffing of PC's, requested RP assistance for various tasks, were knowledgeable of their RWP requirements, and were aware of radiological conditions in their work areas. RP staff support of plant work was very effective in reducing radiological risks. In particular, the drywell entry RP staff was very active in explaining transit routes and survey results to radiation workers, and the refueling floor RP staff actively enforced good RP practices by workers on the deck. In addition, plant
l i
l
!
- -
._
housekeeping was effective in maintaining the plant relatively free of unnecessary materials, equipment, and debris.
R1.2 Reactor Water Cleanuo (RWCU) Flow Element Installation and Pioe Reolacement a.
Insoection Scooe (IP 83750)
The inspector reviewed the as-low-as-is-reasonably-achievable (ALARA) and job planning for the RWCU flow element installation and pipe replacement job, which was the most dose-intensive activity of the refueling outage. The inspector interviewed the ALARA planners for the job, as well as the line supervisor, to determine the scope of the evolution and to assess the planning and execution of the work. In addition, the inspector observed the installation of shielding on the newly installed piping, inspected the general job area, and reviewed pre-and post-job survey results.
b.
Observations and Findinos This job involved the installation of a flow element and associated instrument lines which were to perform an RWCU leakage isolation function foi plant operations. In addition, the plant took this opportunity to replace approximately 30 feet of highly contaminated piping in the same room (a small chamber behind the RWCU heat exchanger room) in order to reduce future dose rates in the area. The original carbon steel piping, which had been in service since 1989, was approximately 3-4 roentgen per hour (r/hr) on contact, and made work in the heat exchanger room very dose-intensive. The new line was a stainless steel pipe with a chromium-electroplated surface, intended to reduce the buildup of radioactive contamination on the pipe walls.
The job and ALARA planning for this job estimated a total dose to workers of 14.1 rem, based on the past pipe replacement evolution in 1989. Based on the lessons learned from that previous evolution, the plant staff decided to use a bandsaw rather than a torch to cut the pipe for disassembly. This change was intended to reduce the total time for the evolution and also to reduce the production of airborne contamination. The pipe was cut into small segments, placed into barrels, and transported to the barrel aisle in the radwaste building. Another change from the previous evolution was the cleaning of the remaining pipe stubs before the welding in of new pipe to reduce installation dose.
The inspector noted that the total job dose at the time of the inspection was about 7 rem, with essentially all of the dose-intensive work done (only disassembly and removal of scaffolding, etc. remained to be done).
In the area of engineering controls, lead shielding was not used for dose reduction during cutting operations because the time that would have been expended for its installation and removal would have counteracted any dose savings. However, some shielding was used for associated instrument rack work. The licensee also utilized portable High Efficiency Particulate Air (HEPA) ventilation units during this operation, in the area of worker dosimetry and job coverage, the cutters and pipe segment transporters wore finger rings, RP technicians observed body positioning to verify proper
dosimetry placement, and the job was assigned continuous RP coverage, which included timekeeping and surveying activities.
Full-face air-purifying respirators were wom by all personnel in the rocm during the pipe cutting operation. The inspector reviewed the respirator ALARA review, which indicated that dose would be slightly loss if respirators were ont worn. However, because the difference was minimal and the uncertainty in the effects of the bandsaw on airborne
]
levels were significant, the licensee allowed workers to elect to use respirators if q
desired. Based on the circumstances of the job and the experience level of the workers,
.
this approach was reasonable and conservative. The inspector identified one deficiency
in the ALARA planning sheet used for respirator selection: the form used to document the calculation for dose incurred while wearing a respirator did not include a term for the internal dose contribution. Essentially, this method assumes an infinite protection factor for respirators. Licensee staff indicated that the absence of this term was not significant j
because the intemal dose contribution would be very small when compared to the extemal dose term and to the uncertainties in the other factors (such as the airborne concentration or the additional time expenditure for wearing a respirator). The inspector agreed with this assessment in part, in that for this particular job, where external doses are high and airborne concentrations are uncertain and/or relatively low, the term would j
have made little difference to the dose estimate and no difference in the selection of respirators. However, tha inspector pointed out that in situations where extemal dose rates are lower and airborne concentrations are higher (particularly if alpha radiation is a concern) and more certain, the lack of this term could affect the decision on whether to issue a respirator. The plant senior health physicist agreed with this analysis and subsequently informed the inspector that this term would be added to the form to prevent possible future errors and that a spreadsheet version was being created to automate and simplify the calculations.
c.
Conclusions The RWCU flow element installation and pipe replacement job was implemented safely and effectively. Improvements were made from lessons teamed in a previous similar evolution and effective methods were used to minimize worker dose. In addition, an appropriate level of RP coverage was assigned to the job and the job ALARA planning was detailed and comprehensive. The licensee's decision to include the pipe replacement in the flow element job demonstrated a commitment to future worker dose reduction.
R1.3 Drvwell In-Service insoection (ISI) Activity a.
insoection Scoce (IP 83750)
The inspector reviewed the ALARA and job planning for the drywell ISI activities, which consisted primarily of visual and ultrasonic equipment and material inspections. The inspector interviewed the ALARA planner for the job to determine the scope of the evolution and to assess the planning and execution of the work. In addition, the
E
inspector observed various drywell inspection points and observed workers performing ISI activities.
b.
Observations and Findinas ISI activities in the drywell were grouped into two RWPs: 509 and 520, which controlled
- typical" dose rate and higher dose rate activities, respectively. The typical dose rate activities included work on the B and C feedwater nozzles and recirculation piping, while the higher dose rate work included ISI on the reactor vessel pipe windows (ports).
The drywell ISI activities included continuous RP r. overage for the higher dose rate jobs and any work occurring on the 951' and 962' elevations, where dose rates where higher.
Also, these jobs included provisions for the use of teledosimetry. The plant had recently acquired a new teledosimatry system, which operated at a lower frequency than their previous system. The reason for this change was because the older, higher-frequency system had the potential to interfere with sensitive instrumentation in the immediate transmission area. Interviews with plant workers and RP personnel at the drywell control point indicated that the system was performing quite well and reception was superior to the old system. Lead shielding had been applied in several areas of the drywell, especially near recirculation risers and piping, to reduce dose rates, in addition, the drywell entry point utilized a timekeeping computer system to track the amount of j
time a worker should remain in the drywell based on dose rates and the RWP. RP staff had also designated two low dose rate standby areas for personnel to use for rest l
periods or between job steps. The inspector observed that radiatiott workers were using l
these areas appropriately.
Drywell ISI doses were at or below projections based on percent of work completed versus percent of dose acquired. For example, with essentially all of the RWP 520 work complete, the total dose acquired was 3.97 rem, versus the projected dose of 7.5 rem.
Most of the credit for this shortfall was due to the continuing reduction of drywell dose
rates as a result of the switch to depleted zine oxide (DZO) injection into the reactor q
coolant in early 1993.
j
!
Though several personnel contaminations from the drywell (and elsewhere) had been recorded on condition reports during the outage, none of the events involved a significant spread of contamination or the potential for an overexposure. Based on a
,
review of these condition reports, the inspector pointed out to RP management that two r
l of the events indicated a possible lack of visual attention to undervessel workers on the
'
part of assigned RP technicians. However, the inspector also noted that no such lack of attention was seen during actual work observed by the inspector during the course of
'
l the inspection.
c.
Conclusions The drywell ISI activities were carefully monitored and controlled by RP personnel and had been assigned appropriate radiological controls based on the dose rates and risk of
,
!
contamination involveJ. The plant continued to see a benefit from DZO injection
!
through reduced dose rates in the drywell.
l l
R1.4 Rebuild and Reolacement of Safety Relief Valve (SRV) Tooworks a.
Insoection Scooe (IP 83750)
l The inspector reviewed the ALARA and job planning for the rebuild and replacement of four SRV topworks, as well as the full valve internal inspection, high torque operation, l
and air fitting leak rate testing for these components. The inspector interviewed the l
ALARA planner for this job and Inspected the work area, located on the 951' elevation of the drywell.
!
b.
Observations and Findinas The ALARA planner for this job indicated that the main radiological concern for the SRV job was the relatively high external dose rates present on the 951' elevation of the drywell, particularly near the reactor recirculation risers and piping. Because of this i
l concern, the ALARA planner concentrated significant attention to proper (conservative)
l dosimetry placement for the workers near this piping. The orientation of the ~ workers with respect to nearby sources was carefully observed during the evolution by RP l
personnel at the job site and/or by remote camera from the drywell entry point to ensure l
that dosimetry was properly positioned. In addition to extemal dose, airbome l
radioactivity was a concem for the breaching of the valves. During this job step, smears i
of valve internals and air samples were taken to assess the extent of contamination. In i
addition, workers were double-gloved and wore dust masks and face shields during high-risk (for contamination) portions of the job. Unlike previous similar evolutions,
'
j workers used a torch to cut the valve bolts off, rather than a saw, in order to increase
,
speed (and thereby decrease dose). Because the bolts were not a source of significant l
contamination or airbome radioactivity, the licensee determined that this method would l
result in a net dose savings.
Smears on the valve intemals indicated contamination levels of about 100,000 - 250,000
l dpm/100 cm, which was within the expected range and similar to values encountered l
during the last outage. Air sample results showed no significant airbome radioactivity and the valve system intemals were covered after the old topworks were removed until replacement pieces could be fitted to the valves.
The inspector noted that a mockup of the SRV had been used by the job crews to plan
,
l their evolutions, though RP did not have direct involvement in this process. Also, the
!
RP ALARA coordinator met with the work crews after completion of the job to perform an ALARA post-Job review, which evaluated the effectiveness of the radiological controls for the job and also reviewed methods to make the job run more smoothly in the future.
However, the inspector noted that the RP planner for this job did not attend this briefing and was unaware of the feedback and the lessons learned. This feedback would have
,
been an opportunity for the ALARA planner to increase his skills and to familiarize himself with potential improvements for future jobs.
l
,
.
c.
Conclusions The ALARASob planning for the SRV topworks rebuild and replacement evolution was adequate. Appropriate engineering controls, dosimetry placement, and RP staff visual coverage contributed to the safe and officient execution of this job. However, the inspector also noted a lack of RP staff involvement in the mockup training for the workers, as well as the absence of any feedback to the job ALARA planner from the post-job ALARA review.
R8 Miscellaneous RP&C lasues (IP 92904)
l R8.1 (Closed) Insoection Follow-uo item 50-263/96010-03: Survey procedure does not require industry accepted lower limits of detection (LLDs) for the unconditional release l
of bulk liquid material. The licensee was using effluent LLDs rather than the industry-l standard environmental LLDs for the counting of bulk liquids for free release. The l
licensee had submitted a technical evaluation to the inspector to justify this decision with respect to safety significance and regulatory wquirements. Though this issue may be reviewed generically by NRC management for further clarification, no violations of NRC requirements were identified by the inspector regarding this practice and no further inspection activity is required. This item is closed.
R8.2 (Closed) Insoection Follow.uo item 50-263/97017-01: Control room personnel not respirator-qualified due to the wearing of beards. This item concerned an inspector observation that one lead control room operator had a beard. The licensee initiated Condition Report No. 97002924 to address this issue. The licensee subsequently performed a thorough analysis of plant policies and procedures related to this item, as well as its safety ramifications. Inspector review of this analysis found that the plant was l
and had been meeting its fire brigade and minimum shift composition requirements by i
appropriate staff selection. The licensee elected to establish an operations policy (in i
Operations Work Instruction OWi-01.06) requiring all operations shift personnel to report l
for duty clean shaven except when medical conditions necessitate otherwise. This action was conservative and potentially increased the reliability of a control room response to an accident. This item is closed.
R8.3 (Closed) Violation 50-263/9800341: Inadequate radiological evaluation performed for an instrument calibration job. This violation involved the contamination of an instrument
l worker with highly radioactive resin. The inspector reviewed the licensee's corrective
actions for this job, which included a staff briefing, an addition to the plant advanced radiation worker training curriculum, and the addition of steps to a line-flushing L
l procedure (Operations Manual B.7.3-05.02," Solid Radwaste System: System i
l Operation") to eliminate the potential for future similar events. These actions were
)
l appropriate and should result in decreased risk of personnel contaminations at the plant.
This item is closed.
!
!
J
n
.
.
'X1 Exit Meeting Summary.
The inspector presented the inspection results to members of licensee management at the conclusion of the inspection on April 9,1998. The licensee acknowledged the findings
- presented.
l l
The inspector asked the licensee whether any materials examined during the inspection should i
be considered proprietary. No proprietary information was identified.
!
l l
l l
l l
!
!
,
i i
'
i-
!
i i
t I
r
.
...
.
.
..
.
.
.
PARTIAL LIST OF PERSONS CONTACTED Licensee i
T. Corrigan, Radiation Protection Specialist j
P. Decker, Radiation Protection Specialist G. Gunther, Construction Superintendent M. Hammer, Plant Manager G. Mathiasen, Senior Health Physicist M. Olson, Radiation Protection Specialist j
W. Shinnick, ALARA Coordinator
{
J. Windschill, General Superintendent, Radiation Services
]
NEC j
i S. Ray, Acting Senior Resident inspector, Monticello D. Wrona, Resident inspector, Monticello INSPECTION PROCEDURES USED IP 83750:
Occupational Radiation Exposure l
IP 92904:
Followup - Plant Support
ITEMS OPENED, CLOSED, AND DISCUSSED Closed 50-263/96010-03 IFl Survey procedure does not require industry accepted LLDs for the unconditional release of bulk liquid material.
50-263/97017-01 IFl Control room personnel not respirator-qualified due,to the wearing of beards, i
50-263/98003-01 VIO Inadequate radiological evaluation performed for an instrument j
calibration job.
I l
i t
.
.
LIST OF ACRONYMS USED
'
ALARA As Low As Reasonably Achievable dpm disintegrations per minute DRS Division of Reactor Safety DZO Depleted Zinc Oxide HEPA High Efficiency Particulate Air IFl Inspection Followup item IP inspection Procedure ISI in-Service Inspection LHRA Locked High Radiation Area LLD Lower Limit of Detection MNGP Monticello Nuclear Generating Plant NRC Nuclear Regulatory Commission PC Personal Contamination Clothing PDR Public Document Room RCA Radiologically Controlled Area RP Radiation Protection RP&C Radiation Protection and Chemistry l
RPM Radiation Protection Manager l
RWP Radiation Work Permit SRV Safety Relief Valve l
VIO Violation I
l
,
l l
,
12 l
.
.
PARTIAL LIST OF DOCUMENTS REVIEWED Memorandum dated 4/2/98 from J. Windschill to File, " Meeting w/l&C and RP on resin job lessons learned" Letter dated 4/1/98 from M. Hammer to US NRC," Reply to Notice of Violation Contained in NRC Inspection Report No. 50-263/98003" (w/ enclosure)
Reactor Coolant Zn-65 Concentrations by Cycle Chart (M7710L-011 Rev.1)
Reactor Coolant Co-60 Concentrations by Cycle Chart (M7710L-011 Rev.1)
Buildup of Activity in Recire Pipe Film Chart (M7710L-011 Rev.1)
Recire Pipe Dose Rates Chart (M7710L-011 Rev.1)
Advanced Radworker Lesson Plan (M-7710L-011 Rev. 0)
Condition Reoorts:
97002924, " Question concerning minimum number of operators that must be respirator qualified."
)
98000489, " Respirator Fit Test Requirements" 98000501," Storage of Rad Mat outside the Protected Area."
98000683, " Personnel contamination of insulator in A RHR"
'
98000754, "Significant percon in RWCU" 98000772, "Significant percon of operator in Drywell" 98000775, "Significant percon of helper in B RHR" 98000795, "Significant percon in Drywell" 98000797, "Significant percon of maintenance on Top of Torus"
,
98000827, "Significant percon in Condenser Room" 98000828, "Significant percon of operator on 1027' Rx."
l
!
Radiation Work Permits (with ALARA Plann;la Worksheetsh l
131 (Rev. 2), " Install new [RWCU pipe, hangers, shleiding and insulation)"
182 (Rev.1), "HP Turbine Repair of the horizontal joint" 509 (Rev. 2), " Perform General ISI, IWE, and EROC inspections in drywell."
l 511 (Rev. 0), " Replace / Rebuild C, H, F, & D SRV topworks..."
512 (Rev. 0), " Snubber changeout in drywell..."
525 (Rev. 0), " Remove / Reinstall Control Rod Drives..."
544 (Rev. 0), " Repair 'D' MSIV includes breech of system and PM 4514-1" 701 (Rev. 0), " Reactor Disassembly & Reassembly..."
Procedures:
Operations Manual B.7.3-05.02 (Rev. 6)," Solid Radwaste System: System Operation" Operations Work Instruction owl-01.06 (Rev. 0), " Duty Operations Personnel Requirements and Responsibilities"
_-