ML20035A006
| ML20035A006 | |
| Person / Time | |
|---|---|
| Site: | 07000903 |
| Issue date: | 03/31/1993 |
| From: | Abelquist E, Reisenweaver D, Wolff J CHEVRON U.S.A., INC., NUCLEAR ENERGY SERVICES, INC. |
| To: | |
| Shared Package | |
| ML20035A005 | List: |
| References | |
| IES-160001, NUDOCS 9303230222 | |
| Download: ML20035A006 (19) | |
Text
_ - - _ - - - _ - _ - -
IES - 160001 FINAL RELEASE SURVEY PLAN OF THE NATIONAL PARK SERVICE PROPERTY LOCATED NEAR PAWLING, NEW YORK FOR CHEVRON USA, INCORPORATED MARCH 1993 PREPARED AND SUBMITTED BY:
INTEGRATED ENVIRONMENTAL SERVICES DIVISION OF NUCLEAR ENERGY SERVICES DR ADO OO 03 C
ins IES - 160001 FINAL RELEASE SURVEY PLAN OF THE NATIONAL PARK SERVICE PROPERTY LOCATED NEAR PAWLING, NEW YORK i
FOR CHEVRON USA, INCORPORATED l
1 l
Prepared by:
U M
Eric W. Abelquist, Proj6ct Manager 1
Approved by:%
sT -
.~
' Dennis W. Reisenweaver, Depanment Manager da/ j.
_I
/
Approved by:
A John TV Iff, Chevron USA, frkorporated Representative
Table of Contents I.
Introduction 1
II.
Release Criteria I
III.
Survey Prerequisites 2
IV.
Survey Procedure 2
Building Sun'ey
'2 General 2
Survey Measurements 3
Surface Scan 4
Direct Measurements 4
Removable Contamination Measurements 5
Exposure Rate Measurements 5
Outdoor Suney 6
V.
Survey Instntmentation 6
VI.
Interpretation of Survey Results 8
VII.
Quality Assurance 9
References 10 Appendix A - Final Survey Forms
I.
Introduction This final release survey plan is an extension of the Decommissioning Plan (Ref.1) for the Plutonium Facility and Multiple Failure Building and the Work Plan for the Soit Remediation (Ref. 2). Specifically, Sections III through V in the Decommissioning Plan which describe the contractor relationships, decommissioning plan control system, and project personnel, will apply to the final release surv:y plan as well.
The objective of the final release survey plan is to outline the required actions necessary for obtaining the uruestricted release of the Nuclear Lake site by the U.S.
Nuclear Regulatory Commission (USNRC). The survey procedures contained herein are consistent with the recommendations of NUREG/CR-5849, " Manual for Conducting Radiological Surveys in Support of License Termination" (Ref 3).
l The final release survey of the Nuclear Lake site will include a building survey of the Plutonium Facility and Multiple Failure Building as well as a site grounds survey of the outdoor soil locations identified in the 1988 Oak Ridge Associated Universities (ORAU) Site Radiological Survey (Ref. 4) as exhibiting elevated contamination levels.
II.
Release Criteria The release criteria established for the Nuclear Lake site decommissioning project include compliance with the surface contamination levels presented in USNRC Regulatory Guide 1.86, " Termination of Operating Licenses for Nuclear Reactors" (Ref.5). Specifically, the surface contamination in the two buildings will not exceed the USNRC guidance as stated below.
For beta-gamma emitters (e.g., Cs-137):
2 2
5000 dpm/100 cm, average (over 1 m ) fixed plus removable contamination, 2
1000 dpm/100 cm, removable contamination, and 2
2 15,000 dpm/100 cm, maximum (not more than 100 cm ) fixed plus removable contamination.
For transuranic contamination (e.g., plutonium isotopes):
2 2
100 dpm/100 cm, average (over 1 m ) fixed plus removable contamination, 2
20 dpm/100 cm, removable contamination, and 2
2 300 dpm/100 cm, maximum (not more than 100 cm ) fixed plus removable contamination.
I
In addition to the USNRC Regulatory Guide 1.86 requirements, exposure rates may not exceed background by more than 5 gR/h, measured at 1 meter from building surfaces.
Soil contamination levels will comply with USNRC agreed upon limits of 25 pCi/g for plutonium isotopes and 15 pCilg for Cs-137. Further guidance will be sought from the USNRC if additional radioactive contaminants are identified in the soil.
III.
Survey Prerequisites The following survey prerequisites will be performed prior to the commencement of the final release survey:
(1)
Instrument calibrations will be current for all equipment used during the Gnal release survey. This includes all survey meters, detectors and air samplers.
(2)
The final release survey will be performed by trained Radiological Controls Technicians who are quali6ed in Gnal survey procedures.
(3)
Daily response check determinations will be made for all survey instrumentation used during the Gnal release survey. This includes all beta-gamma and alpha probes, smear counters and exposure rate survey meters.
IV.
Survey Procedure The ORAU 1988 Site Radiological Survey sen'ed as a guide to effectively classify the Nuclear Lake site into affected and unaffected areas. Speci6cally, the affected building areas were taken as these facilities containing residual activity above USNRC release criteria, i.e., the Plutonium Facility and the Multiple Failure Building The affected soil areas are located immediately north of the Plutonium Facility, south of the Waste Disposal Building, with one small area near the downspout of the Shield Mock-up Building. The remaining areas are classified as unaffected areas based on the ORAU survey and will not undergo further release survey activities.
Buildine Survey General Survey measurements for surface activity will consist of a combination of surface scans, direct (i.e., fixed plus removable) contamination measurements, and removable surface contamination measurements. The surface scan is intended to identify the 2
l l
presence of elevated direct radiation that might indicate residual activity or hot spots.
The surface scan will be conducted for all radiations potentially present, i.e.,
plutonium isotopes and Cs-137. Systematic measurements of direct and removable surface contamination will be performed to quantify the levels of residual activity.
The building surfaces will be prepared prior to performing the survey measurements.
This preparation may include the removal of equipment and materials to obtain access to potentially contaminated surfaces, e.g., removing wall and Goor cove-ings, opening drains and ducts. The surfaces must be free of dust and water, which may attenuate alpha and low energy beta radiation.
Survey maps will consist of scale drawings of the survey area, indicating facility features, superimposed on the grid reference system.
Equipment (e.g., lab benches, fume hoods) within the buildings that was used directly for processes or activities involving radioactive materials will be surveyed. Piping, drains, sewers, sumps, tanks and other components of liquid handling systems will be surveyed at available access points. Samples will be collected as necessary for radiological analysis.
The Gnal release survey for the plumbing will consist of direct and removable contamination measurements obtained at the access point of each Door drain, sump, drain line, etc. Contamination measurements will be obtained with both beta / gamma and alpha detection instrumentation.
Expansion joints, stress cracks, and penetrations into floors and walls for piping, conduit, exhaust ventilation and surfaces around these exhausts, etc., will be surveyed as potential sites for contamination accumulation.
Surver Measurements A grid system will be established within each building to facilitate the systematic selection of survey locations and to provide a mechanism for referencing a suney measurement back to a speci6c location for possible further'remediation. A grid system also will facilitate the determination of average activity levels.
The basic grid system will consist of dividing the floors and lower walls (up to 2m heights as deGned in Ref. 3) into 1 meter grids. The upper walls and the ceilings will not be gridded unless there is evidence that these surfaces are contaminated. Suney measurements performed on ungridded surfaces will be referenced to the floor grid or to prominent building features.
3
Surface Scan Initially, a 100% surface scan survey will be performed for the Door and lower wall surfaces. A ratemeter/ scaler connected to a GM pancake probe will be used to perform the surface scan since this detector arrangement is sensitive to both aipha and beta-gamma radiation. The surface scan is perfonned by keeping the detector as close to the surface as possible (about I cm) and moving the detector at a slow speed (i.e.,
speed should not exceed one detector width per second for alpha and beta radiations).
Areas of elevated surface activity will be noted by changes.in the audible signal from the survey meter, rather ths.n by observing Ductuations in the analog / digital meter reading.
Locations of areas of elevated activity identified by the surface scan will be marked on the surface and documented on the appropriate survey form (Appendix A). Direct measurements will be taken to determine the extent of residual activity. Residual activity that exceeds the guideline value for fixed plus removable surface 2
contamination, i.e., 5000 dpm/100 cm for beta / gamma emitters and 100 dpm/100 cm; for plutonium isotopes, will be remediated. Direct measurements will be repeated following the hot spot decontamination.
Direct Measurements For all building surfaces, i.e., Doors, lower and upper walls, and ceilings, a minimum of 30 measurement locations for each surface will be collected. One direct beta-gamma and one direct alpha surface contamination reading will be taken from the center of each Door and lower wall grid. Each direct measurement will be one minute in duration. The Ludlum 2221 meter and 44-9 GM pancake probe, or equivalent instmmentation, will be used to perform the beta-gamma direct measurements, while the Ludlum 2220 meter and 43-5 alpha scintillation probe, or equivalent instrumentation, will be used to perform the alpha direct measurements.
Direct measurements indicating the presence of residual activity that exceeds the guideline value will be remediated. Direct measurements will be repeated following the hot spot decontamination.
Additional measurements will be necessary for direct measurements indicating the presence of residual activity that exceeds 60% of the guideline value (i.e.,3000 2
dpm/100 cm for beta / gamma emitters and 60 dpm/100 cm for plutonium isotopes).
An estimate of the elevated activity area will be performed and recorded. Five additional measurements will be performed at random locations within the grid, but outside of the elevated activity area. The average residual activity value reported on the survey form will be calculated by:
l 4
^
A x" = [
][1-10,000] + [y] [ 10,000 ]
(1) n
- where, x,= weighted mean residual activity for the 1 m grid, 2
x, = residual activity of each additional direct measurement, n = number of additional residual activity measurements (= 5),
A = area occupied by the elevated activity within the grid (in cm ), and 2
y = measurement of elevated residual activity (i.e., exceeds 60% of guideline value).
l The elevated residual activity area will be remediated if the average residual activity for the grid exceeds the guideline value.
For ungridded surfaces, i.e., upper walls and ceilings, a minimum of I measurement 2
per 20 m of surface area will be collected. At each measurement location a scan of the immediate area will be performed to identify the presence of any elevated residual activity, followed by the measurement. If the measurements of the ungridded surfaces indicate that residual activity exceeds 25% of the guideline, the area is considered potentially contaminated and the surface will be surveyed in the same manner as the floor and lower wall surfaces.
Removable Contamination Measurements A smear for removable contamination will be collected at each location of direct surface ac:ivity measurement. The smears will be obtained by wiping an area of 2
approximately 100 cm using a dry filter paper, or equivalent. The smears will be placed in an envelope to minimize the potential for cross-contamination.
Each smear will be counted on a Canberra Model 2400 automatic smear counter, or equivalent instmmentation, for measurements of alpha, beta and gamma removable surface contamination. The results of the removable surface contamination suney will be documented on the appropriate suney form.
Surfaces with smear results exceeding the guideline value will be remediated and the surface resurveyed.
Emosure Rate Measurements Exposure rate measurements will be obtained at I meter from floor and lower wall surfaces. These measurements will be performed at a frequency of I systematic 5
measurement per grid. The Bicron Micro-Rem meter, or equivalent meter, will be used to obtain the exposure rate measurements.
Background exposure rate measurements will be taken with the Bicron Micro-Rem meter in. unaffected locations within other buildings at the Nuclear Lake site. The background exposure rate will establish the 5 R/h above background release criteria.
Outdoor Surrev The 1988 ORAU Site Radiological Survey identi0es two areas as exceeding i
radiological release criteria established for the soil remediation. The areas are located immediately north of the Plutonium Facility and south of the Waste Disposal Building.
An outdoor grid system will be established for each affected soil area. The basic grid system will consist of dividing the excavated soil area into 5 meter grids.
The affected outdoor soil areas will be scanned with a ratemeter/ scaler connected to a NaI probe (e.g., Ludlum 2221 meter and Eberline PG-2 low energy gamma probe).
Areas of elevated suspected activity, identified in this manner, will be marked and evaluated by sampling and analyses to determine their activity concentrations. The soil samples collected south of the Waste Disposal Building will be analyzed by gamma spectrometry for the presence of Cs-137, while the samples collected nonh of the Plutonium Facility will be analyzed by alpha spectrometry for plutonium isotopes.
Exposure rate measurements will be performed at I meter above the surface of each grid block center. The exposure rate survey results will be documented on the appropriate survey forms.
V.
Survey Instrumentation A Tc-99 electroplated beta source will be used to determine the ef0ciency of the GM pancake probes and the smear counter. The Tc-99 source was chosen because it will provide a conservative estimate of the Cs-137 residual activity. The conservatism results from the fact that the beta endpoint energy of Tc-99 (292 kev) is less than that of Cs-137 (512 kev), and the higher beta energies of Cs-137 result in higher actual detection efficiencies than that determined with Tc-99.
A jig will be used to ensure a reproducible geometry during the daily instmment performance checks. The Tc-99 ef0ciency for the Ludlum 2221 and 44-9 is approximately 0.18 counts per disintegration, while the Th-230 (4.68 Mev) efficiency for the Ludlum 2220 meter and 43-5 alpha scintillation probe is approximately 0.25 I
i 6
1 l
1
_J
counts per disintegration. This efficiency will be used for the measurement of Pu-239, which has a similar alpha energy (5.16 Mev).
The Cs-137 beta detection efficiency for the Canberra Model 2400 automatic smear counter is approximately 0.42 counts per disintegration and the Pu-239 alpha efficiency is 0.35 counts per disintegration.
The minimum detectable activity (MDA) will be calculated for both the fixed contamination survey instrumentation (e.g., Ludlum 2221 and 44-9 GM pancake probe and Ludlum 2220 meter and 43-5 alpha scintillation probe ) and the smear counter. The MDA will be calculated by the following equation (Ref. 6):
2.71 R
R 3 +3
+ 3.29 T'
\\
T*
T' (2)
MDA=
(eDiciency) (F k "'* ),
100 cm'
- where, R, = Background counting rate (cpm),
T = Background count time (min), and 3
T, = Sample count time (min).
The MDA for the Ludlum 2221 and 44-9 GM pancake probe will be calculated in the same units as the fixed contamination results (i.e., dpm/100 cm ). As an example, the MDA for the Ludlum 2221 (serial # 73683) and 44-9 (serial # 057871) may be calculated for a background counting rate of 60 cpm:
2.71 60 mm
@ ym
+ 3.29 1.0 min T 1.0 min 1.0 min MDA =
(3) 2 (0.18 c/ dis)( 15 cm )
2 100 cm or, J
7
MDA = 1440 (4) 2 100 cm Thus, the MDA is less than one-third of the average surface contamination level 2
(5000 dpm B-y/100 cm ) in USNRC Regulatory Guide 1.86.
Using Equation 1, the MCA for the Ludlum 2220 meter and 43-5 alpha scintillation 2
probe is calculated to be 59 dpm/100 cm, assuming an alpha background of I cpm, count time of 1 minute and detection efficiency of 0.25 counts per disintegration.
The MDA will be calculated in a similar manner for the Canberra automatic smear counter. However, no correction for probe area will be necessary to convert to units 2
2 of dpm/100 cm since the smeared surface area will be approximately 100 cm. The background counting rate for the smear counter will be determined by a 30 minute count (typical background count rates are 1 cpm and 0.1 cpm for beta and alpha emitters, respectively). The MDA for the smear counter is approximately 15 2
2 dpm/100 cm for Cs-137 (about 1.5 % of the 1000 dpm/100 cm guideline for i
removable surface contamination) and 11 dpm/100 cm for Pu-239 (about 55% of the 2
2 20 dpm/100 em guideline value for removable surface contamination).
VI.
Interpretation of Survey Results The survey data will be recorded ento the appropriate survey forms. The direct contamination readings will be converted to dpm/100 cm using the following formula 2
(probe area for the Ludlum 44-9 GM pancake probe was 15 cm ):
2 dpm/100 cm2, Rron cpm - Mgroud cpm (5)
(ejicr.ency) (probe area) 100 cm,*
The average background count rate 'or the direct survey instrumentation will be determined by a series of three 1 minute counts. Each direct measurement of fixed contamination will be 1 minute in duration. If the direct measurement results in a value les, than the calculated minimum detectable activity for the survey 8
_.______-_____--m_
--mm___
-m
instmmentation, this will be so stated on the survey documentation.
The final release survey repon and supporting documentation (e.g., survey forms) will be prepared in Danbury and subndtted to Chevron USA, Inc. and the National Park Sen' ice.
VII.
Quality Assurance The Quality Assurance Program Plan (QAPP), NES procedure 82A8027, will be implemented during the Nuclear Lake site decommissioning project. This plan establishes the basis for assuring the adequacy and quality of the final release survey data. The elements of this plan include, in pan, daily instrument performance checks, data review of the final release surveys, accuracy of devices used for radiological sampling, and the use of properly calibrated instmmentation.
Contamination control practices will continue to be followed during the final release survey. These practices include personal frisking out of the radiologically controlled areas (RCAs), preventir.g survey instmmentation to come into direct contact with surfaces potentially contaminated with loose activity and ensuring that sampling equipment is cleaned between sample collections. These practices will minimize the potential for personal contamination and the cross-contamination of samples.
A chain +f-custody form will accompany all radiological samples collected during the Nuclear Lake site decommissioning project. This sample management practice will ensure that the integrity of the sample is maintained by providing a record of sample collection, transport, analysis and disposal. The chain-of-custody ensures that the sample analyzed in the laboratory is the actual sample collected from a specific location in the field.
As stated in the QAPP, there will be at least one NES/IES audit of the decommissioning activities and records. The audit will verify compliance with the requirements of the QAPP and the referenced procedures.
l 9
References 1.
" Decommissioning Plan for the Plutonium Facility and Multiple Failure Building of the National Park Service Located Near Pawling, New York." February 1993.
2.
" Work Plan for the Soil Remediation of the National Park Service Property Located Near Pawling, New York." November 1992.
3.
NUREG/CR-5849. " Manual for Conducting Radiological Surveys in Support of License Tennination"; 1992.
4.
Berger, J.D. et al. " Radiological Survey of the Nuclear Lake Site, Pawling New York," Oak Ridge Associated Universities: 1988.
5.
USNRC " Regulatory Guide 1.86. " Termination of Operating Licenses for Nuclear Reactors"; 1974.
6.
Strom, Daniel J. and Stansbury, Paul S. " Minimum Detectable Activity When Background is Counted Longer Than The Sample." Health Physics 63(3):360-361; 1992.
l 10
APPENDIX A FINAL SURVEY FORMS
ELETATED READINGS CONTAMINATION RESULTS DATE:
LOCATION:
INSTRUMENT-PROBE:
EFF:
Model PRE-DECONTAMINATION RESULTS POST-DECONTAMINATION RESULTS GRID NUMBER CPM dpm/100cm2 GRID NUMBER CPM dpm/100cm2 Average background counts per min.
2 NOTE:
DPM/100 cm calculated as follows-dom (gross count rate)-(backaround count rate) 100cm2 (efficiency)
(orobe area)
SURVEYOR 100cm 2 SUPERVISOR
AVERAGE CONTAMINATION SURVEY RESULTS DATE:
LOCATION:
INSTRUMENT-PROBE:
EFF:
MODEL NUMBER MODEL GRID NUMBER dom /100cm2 GRID NUMBER dpm/100cm2 Average Background counts per minute
- BASED ON AVERAGE OF 5 DIRECT MEASUREMENTS (INITIAL DIRECT MEASUREMENT WAS GREATER THAN 60% OF GUIDELINE VALUE) dom (cross count rate)-(backcround count rate)
SURVEYOR 100cm 2 (efficiency)
(crobe areal 100cm 2 SUPERVISOR
AVERAGE CONTAMINATION SURVEY RESULTS dpm/loocm 2 DATE:
LOCATION:
INSTRUMENT:
PROBE:
EFF:
Model Number Model GRID NUMBER GRID NUMBER GRID NUMBER GRID NUMBER 1.
1.
1.
1.
2.
2.
2.
2.
3.
3.
3.
3.
4.
4.
4.
4.
5.
5.
5.
5.
X X
X X
GRID NUMBER GRID NUMBER GRID NUMBER GRID NUMBER 1.
1.
1.
1.
2.
2.
2.
2.
3.
3.
3.
3.
4.
4.
4.
4.
5.
5.
5.
5.
X X
X X
GRID NUMBER GRID NUMBER GRID NUMBER GRID NUMBER 1.
1.
1.
1.
2.
2.
2.
2.
3.
3.
3.
3.
4.
4.
4.
4.
5.
5._
5.
5.
X X
X X
Average Background counts per minute NOTE:
Results recorded in DPM/100cm2 using the formula:
dom
(
_ oross count rate)-(background count rate) SURVEYOR
~
I 100cm 2 (efficiency) (orobe area) 100cm 2 SUPERVISOR l
REMOVABLE CONTAMINATION DATE:
LOCATION:
COUNTER:
EFFICIENCY:
Model Number Alpha Beta / Gamma DPM/100cm2 DPM/100cm2 DPM/100cm2 SMEAR #
Qy a
SMEAR #
py a
SMEAR #
Qy n
ALPHA BKG COUNT RATE:
BETA / GAMMA BKG COUNT RATE:
SURVEYOR l
SUPERVISOR
DATE-LOCATION:
INSTRUMENT-CAL DUE:
EXPOSURE RATE EXPOSURE RATE GRID NUMBER urem/h GRID NUMBER nrem/h lem 1m lem im MEASUREMENTS TAKEN AT 1cm AND/OR 1m ABOVE THE FLOOR.
SURVEYOR SUPERVISOR