IR 05000528/1991002
| ML17305B370 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 02/05/1991 |
| From: | Tenbrook W, Yuhas G NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | |
| Shared Package | |
| ML17305B369 | List: |
| References | |
| 50-528-91-02, 50-528-91-2, 50-529-91-02, 50-529-91-2, 50-530-91-02, 50-530-91-2, NUDOCS 9102270146 | |
| Download: ML17305B370 (9) | |
Text
0 U.
S.
NUCLEAR REGULATORY COMMISSION
REGION V
Report Nos.
50-528/91-02, 50-529/91-02, 50-530/91-02 License No.
NPF-41, NPF-51, NPF-74 Licensee:
Arizona Public Service Company P.
Q.
Sox 52034 Phoenix, Anzona 85072-2034 Facility Name Palo Verde Nuclear Generating Station Units 1, 2 and
Inspection at:
Wintersburg, Arizona Inspection Conducted:
January 22-25, 1991 Approved by:
~Summer:
Inspected by: N~ Is~
en roo, a )a )on pec)a )s u as,
)e Reactor Radiological Protection Branch e
ne Areas Ins ected:
Inspection of occupational exposure during outages and
)nspec or o
owup items.
Inspection procedures 83729 and 92701 were used.
Results:
The following areas are discussed in Section 3 below:
The resources provipred for ALARA eng>nearing were generous, given the scope of the Unit I surveHlance outage.
The unexpectedly high crud-burst upon shutdown and the resulting heightened dose rates in some plant areas were underestimated in the cost/benefit analysis for chemical cleaning of the reactor coolant system prior to the short-duration outage, but did not appear to alter the outcome of the cost/benefit comparison.
Thorough instructions to workers in controlled areas was a program strength.
Air sampling for radioiodine in controlled areas was not consistently performed in and around locations where iodine was potentially present.
No violations were identified.
9>oza7o>4s 9>olios PDR ADDCK 05000528 G
DETAILS Persons Contacted Licensee.
J. Albers, Radiation Protection Operations Manager W. Barley, Acting Manager, Radiation Protection Technical Services N. Bryant, Technical Assistant, Nuclear Training K. Coon, Radiation Protection Supervisor, Unit 1 R. Flood, Plant Manager, Unit 2 R. Fountain, equality Assurance Deficiency Supervisor P.
Guay, Chemistry Manager, Unit 3 S..Guthrie, Deputy Director, equality Assurance R. Hazelwood, equality Assurance Supervisor R. Henry, Site Representative, Salt River Project.
P.
Hughes, Radiation Protection General Manager.
M. Ide, Plant'Manager, Unit 1 D. Kanltz, Compliance Engineer S. Kanter, Senior Coordinator, Owner Services J.
King, Chemistry Supervisor, Unit 1 A. Ogurek, Corporate Assessment Manager M. quinn, Licensing Director R.
Rouse, Compliance Supervisor J. Scott, Site Chemistry General Manager M. Shea, Radiation Protection Manager, Unit 2 J. Sills, Corporate Assessment Rad)ation Protection D. Sneed, Radiation Monitoring System Supervisor, Unit 2 Nuclear Re viator Commission D.
Coe, Senior Resident Inspector The persons'isted above attended the exit meeting held January 25, 1991.
The inspector also held discussions with other personnel during the inspection.
Fol 1 owu (92701 0 en Item 50-529/90-19-03 (Closed):
This item concerned adequacy of on-e-~o rasnsng an qua s
>ca ion of junior radiation protection technicians.
This item was previously examined in inspection report 50-529/90-55.
The licensee had since developed an action plan documented by correspondence from J.
Bungard to T. Bradish dated January 3, 1991.
The action plan included development of a job task list, an outage junior radiation protection technician training program and amendment of qualification requirements.
The inspector had no further questions in this matter.
0 en Item 50-528/90-43-02 (Closed):
This item concerned the development o
correc son ac ors or so one plateout in sampling lines.
Calculation 13-NC-Sg-200 for iodine and particulate plating, was completed December 10, 1991, incorporating actual flow rates, measured particle size
distribution and chemical species data from Electric Power Research Institute report NP-939.
Procedure 74RM-9EF60,
"RMS Sample Collection,l'as issued on December 28, 1990, using the new plateout calculation results.
The inspector had no further questions in this matter.
0 en Item 50-528/90-43-03 Closed):
This item concerned the need for gus ance o per orm ra sa son monitoring system (RHS) setpoint determinations and periodic assessment of total dose equivalence factors for gaseous effluent.
The licensee had issued procedure 74RH-9EF42,
"RHS Setpoint Determination,"
on December 12, 1991; to provide the needed guidance.
The current dose equivalence factor, mRem/year per uCi/ml, was based on a default radionuclide mixture for 1X failed fuel obtained from the plant vendor safety analysis.
Preliminary evaluations of mixtures in grab samples indicated that the default mixture provided a conservative dose equivalent factor, chiefly because Kr-88 concentrations were overestimated.
Procedure 74RH-9EF42 specified annual reevaluation of the dose eqvivalence factor based on data from the semiannual effluent release reports.
The most conservative dose equivalence factor from either the default mixture or the historical mixture would be employed.
The inspector had no further questions in this matter.
Unresolved Item 50-530/90-56-02 (Closed
This item concerned measuremen o
air par icu a es on ao )ne cartridges.
This observation resulted from Cs-137 deposited on an iodine cartridge during a month-long sample from RU-1, containment atmosphere monitor.
The inspector reviewed several effluent release permits and their associated gamma isotopic data and did not identify any instances were air particulates had deposited on iodine cartridges.
In addition, radiation protection addressed the concern by analyzing particulate filters and
. iodine cartridges as a package, employing a single library for nuclide identification.
The inspector concluded the licensee was in compliance with 10 CFR 20.201. io this matter.
Occu ational Ex osure Durin Outa es 83729)
Kee in Ex osures As-Low-As-Reasonabl-Achievable ALARA)
The inspector reviewed the licensee's program to maintain radiation doses ALARA during the Unit 1 surveillance outage.
The licensee.s radiological engineering group typically reviewed high-dose tasks such as steam generator entries and reactor coolant pump maintenance.
Since the scope of the surveillance outage did not involve typical refueling outage work, radiological engineering had devoted additional attention to areas historically assigned to ALARA work planning within the affected Unit, such as local leak rate testing, motor operated valve testing and valve maintenance.
In preparation for the outage, radiation protection management had reviewed the option of conducting chemical cleaning of the reactor coolant system to reduce outage dose rates.
The review determined that the cost in critical path time for reactor coolant system recirculation and cleanup could not be justified under cost-benefit analysis at the procedural
$8500/person-rem threshold.
The review determined that the reactor coolant system cleanup would provide a net benefit for outages of
greater length with tasks involving higher dose rate areas, such as refueling outages.
Hanagement's conclusions on coolant system cleanup were documented by correspondence dated July, 17, 1990, from the radiation protection general manager to-the general manager, outage planning, and included a commitment to conduct reactor coolant system chemical cleanup prior to refueling outages.
Prior to shutdown,
"A" train systems showed ~eneral dose rates of 80 mR/hr in the west wrap penetration area.
'-'B train systems showed 3b mR/hr in the east wrap area.
Upon initiation of shutdown cooling, crud burst resulted in 200 to 300 mR/hr dose rates that were not immediately mitigated by shutdown cooling purification.
These dose rates, were higher than the 120 to 150 mR/hr anticipated.
Radiological engineers stated that they could not readily predict the effects of crud burst in a given shutdown.
However, radiological engineering performed ALARA evaluations on most jobs on the basis of work scope and survey data reflecting the higher dose rates.
Only local leak rate tests were evaluated using historical dose data.
,To address the higher dose rates radiological engineering and Unit 1 radiation protection took steps to provide alditiona1 shielding, particularly in the east wrap areas where significant local leak rate testing was to take place.
There 'were no significant hot spots that would have benefitted from flushing.
Malkdowns to confirm A1.ARA precautions and practices were performed and documented, with participation of radiological engineers in shield placement and surveys.
Ouring tours of the auxiliary building, the inspector noted that "cold area" postings were placed in low dose rate areas of the penetration rooms to direct workers away from high dose rate areas.=
However, during tours of containment outside the bioshield, the inspector did not observe any cold area postings in the perimeter of the containment.
The inspector observed that containment'perimeter dose rates ranged from less than 2 mR/hr to greater than 50 w/hr next to contaminated components such as some safety injection system check valves, with no instructive
~
~
osting provided to assist workers in avoiding higher dose rate areas.
he inspector informed radiation protection of thss discrepancy and the signs were subsequently posted.
Observation of Radiation Protection Activities The inspector conducted extensive tours of the containment, auxiliary building, radwaste building and radioactive material storage areas.
The inspector observed radiological work practices and conditions performing independent surveys using dose rate instrument NRC 015844, calibrated January 8, 1991.
Immediately prior to the inspection, a pipe break occurred in the chemical drain tank pump room, 40'levation auxiliary building, between the chemical waste drain tank and a drain tank pump.
The floor of the room had been contaminated with standing water and one operator incurred minor contamination of one shoe while investigating the spill.
The inspector noted during a midweek tour that the area outside the berms surrounding the pumps had been promptly decontaminate Prior to entering the controlled area, the inspector observed thorough briefings of all-personnel signing radiation exposure permits.
The briefing included highlighting.specific briefing notes provided with the radiation exposure permit and emphasis of current radiological conditions recorded on survey maps and shift turnover logs.
In addition, virtually all rooms in controlled areas possessed lucite survey map holders with weekly'nd monthly survey data outside the room entry.
These steps demonstrated compliance with 10 CFR 19.12, '-'Instructions to Morkers."
The inspector observed the preparations to enter the bioshield to decontaminate resistance temperature detectors and differential pressure instrumentation on a reactor coolant system hot leg..
The workers were fully suited in protective clothing, plastic outer suits and respirators.
Precautionary surveys were performed to ensure that the workers were not contaminated prior to entering the work area, so as. to bound the time of any skin exposure due to contamination.
During preparations to enter the area, the radiation protection technician discovered that the scaffold was not tagged as ready for use.
The area coordinator was notified and learned that laborers had neglected to remove the warning tag.
The workers waited approximately fifteen minutes outside the bioshield labyrinth, a low dose rate area.
The lead radiation protection technician instructed the workers to lie on the concrete floor to remain cool.
Once the scaffold was verified safe, the wor k proceeded without incident.
The inspector concluded that radiation protection reacted appropriately to the delay.
Later the inspector learned that the actual maintenance on the hot leg instrumen 'ation had been delayed due to unforseen equipment problems, Although he inspector recognized that the observed delays were isolated and anecdd al, the inspector nonetheless emphasized vigilance over workplace pr paration to prevent delays and min>m>ze radlat)on dose.
)
During tours of the radwaste storage yard adjacent to Unit 1,'he inspector surveyed one cargo van on the north side of the fuel building, measuring dose rates approaching 2 mR/hr, the licensee's dose rate criteria for 10 CFR 20.203 "Radiation Area" boundaries.
The observation was brought to the attention of radiation protection for their independent confirmation and the boundary was posted.
Air Sam lin Methods On January 17, 1991, surveillance testing on components in the letdown isolation path required draining of isolation valve VM-75, which had body-to-bonnet leakage, and associated draining of the regenerative heat exchanger to the reactor drain tank.
A vent path was established to the 100'levation floor drains and sumps through which the regenerative heat exchanger could take suction to displace drained water.
It was expected that any movement of gas would be from the floor drain/sump system into the regenerative heat exchanger.
During the draininq, radiation protection personnel detected increasing dose rates sn containment and
'nitiated a containment evacuation.
Gas'grab samples on the 140'nd 100'levations of containment were 18 and 292 times maximum permissible concentration (MPC), respectively.
A particulate-and iodine sample obtained outside the regenerative heat exchanger cubicle totaled 0.02 MPC
The air sampling performed during and following the gas release was appropriate.
Approximately thirty persons were evacuated and surveyed.
Xe-133 was the contaminant identified during surveys and investigatory whole-body counts.
Maximum skin doses to one-operator and one radiation protection technician were estimated at 39 mrem each.
Consultations between operations and radiation protection had concluded that leakage through auxiliary spray valves between the 'pressurizer and the regenerative heat exchanger had allowed the 100 psi pressurizer gas bubble to leak into the heat exchanger during draining, subsequently dischargi ng through the vent path to the floor drains and into containment.
Radiation protection management stated that jobs involving, interfaces with the pressurizer gas space would be reviewed to prevent recurrence of such releases.
During review of Unresolved Item 50-530/90-56-02, the inspector learned that many of the air samples obtained to track concentrations of radioactive material in Unit 1 work areas were exclusively particulate samples.
Procedure 75RP-9RP01,
"Airborne Radioactivity Sampling Methodology Evaluation and Exposure Trackinp," contained instructions for particulate-only sampling using a "dummy iodine cartridge.
However there was no description of circumstances under which particulate-only samples were appropriate.
The inspector consulted the licensee's air sample log and noted several particulate-only surveys in areas where work was performed on systems contaminated with residual iodine, such as the decontamination of the chemical waste drain tank spill and repacking of valves associated with the letdown heat exchanger.
The inspector expressed concern to radiation protection management as to the adequacy of these surveys given that these components contained residual iodine-131 and iodine-132 at ten days after shutdown.
The radiation protection general manager and radiation protection operations manager also expressed concern over the current practice, but-contended that the specific samples identified by the inspector were adequate to meet the requirements of 10 CFR 20.201,
"Surveys."
Radiation protection management provided the inspector a copy of the weekly routine survey schedule which designated various areas for gas, particulate or iodine surveys, or combinat,ions thereof, demonstrating that guidance was available for types of air sampling in specific areas.
The inspector agreed that the specific instances identified did not conclusively present a radioiodine hazard requiring iodine survey under
CFR 20.201, but that the frequency of particulate-only surveys in areas with iodine contamination invited potential noncompliance.
Radiation protection management agreed and immediately issued a "Night Order" to each Unit directing that particulate and iodine surveys be performed together until management had reviewed current procedures.
Conclusions
The resources provided for ALARA engineering were generous, given the scope of the Unit 1 surveillance outage.
The unexpectedly high crud-burst upon shutdown and the resulting heightened dose rates in some plant areas were underestimated in the cost/benefit analysis for chemical
cleaning of the reactor coolant system prior to the short-duration outage, but did not appear to alter the outcome of the cost/benefit comparison.
Thorough instructions to workers in controlled areas was a
program strength.
Air sampling for radioiodine in controlled areas was not consistently performed in and around locations where iodine was potentially present.
No violations were identified.
4.
~Eit ft ti The inspector met with licensee management on January 25, 1991 to discuss the scope and findings of the inspection.
The inspector presented the status. of inspector followup items and observations regarding radiation protection practices.
The licensee's representatives acknowledged the inspector's observation ~
'