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Reference 10 (Part 1of3)-
WNYNSC Off-Site Radiation Investigation, Volume I- Summary Report (D&M, 1995)
Reference 10 - WNYNSC Off-Site Radiation Investigation, Volume 1 New York State Energy Research and Development Authority Western New York Nuclear Service Center Off'-Site Radiation Investigation Volume I: Summary Report
- DAMES & MOORE
WESTERN NEW YORK NUCLEAR SERVICE CENTER OFF-SITE RADIATION INVESTIGATION VOLUME I:
SUMMARY
REPORT December 1, 1995 Prepared by: Dames & Moore One Blue Hill Plaza, Suite 530 Pearl River, NY 10965
Contact:
Larry W. Luckett, CHP Project Manager NYSERDA Project Manager: Martin J. Willett Contract Number: 2003-WV-RWM-92 Task Order D&M-92-3 Note: The WNYNSC Off-Site Radiation Investigation discussed in this report is fully described in three separate volumes:
- Volume I: Summary Report, December 1995
- Volume II: Technical Report, December 1995
- Volume Ill: Technical Data Annex, December 1995
WESTERN NEW YORK NUCLEAR SERVICE CENTER OFF~ITE RADIATION INVESTIGATION
SUMMARY
REPORT OVERVIEW In November 1993, the New York State Energy Research and Development Authority (NYSERDA) contracted with Dames & Moore to perform radiological measurements in an area adjacent to the boundaries of the Western New York Nuclear Service Center (WNYNSC). The WNYNSC Off-Site Radiation Investigation was designed to confirm the radionuclide distribution reported by previous aerial and ground surveys, to define the location of elevated regions of radioactivity with better precision than the aerial surveys, and to estimate the radiation d~se to residents associated with the radioactive materials and the radiation distribution observed.
The WNYNSC site is located approximately 50 kilometers (30 miles) south of Buffalo,
- New York. The WNYNSC occupies 1,354 hectares (3,340 acres) almost entirely within the town of. Ashford in Cattaraugus County. Title to the WNYNSC is held by NYSERDA on behalf of the people of the state of New York. Facilities at the WNYNSC include a former commercial nuclear fuel reprocessing plant. The fuel reprocessing plant was operated by Nuclear. Fuel Services, Inc. (NFS) from 1966 to 19'n. In 1968, NFS reported an airborne release that exceeded the release rate authorized under its operating license. During the release, the winds carried the material to the west and northwest, some of it reaching areas outside the WNYNSC boundary (NFS, 1968).
Aerial surveys performed in the vicinity of the WNYNSC in subsequent years (EG&G, 1981 and EG&G, 1991) have demonstrated:
WNYNSC Off-Site Radiation Investigation S-1 December l, 1995
- The total gamma radiation exposure rates in off-site areas around the WNYNSC were not elevated in any distinctive pattern and were comparable to natural background in other pans of Western New York.
- Measurements focused on only Cs-137 gamma radiation indicated an area of elevated radiation levels running approximately 4 km northwest from the NFS process building main stack, as shown on Figure SI. The Cs-137 gamma radiation exposure rates in this *cesium Prong* were only slightly above the ambient levels observed at other locations around the site boundary. The presence of Cs-137 was observed by using instruments set to detect the gamma radiation energy of only this radionuclide.
- The Cs-137 gamma radiation from man-made origins was detectable, but the radiation exposure levels measured are less than the fluctuation in natural background radiation in the Western New York area.
The objective in conducting the current evaluation of radioactive material distribution in
. off-site properties was .to obtain better data for use in the joint environmental impact statement underway for completion of the West Valley Demonstration Project (WVDP)
- and closure of existing facilities at the WNYNSC. The data will also be useful to detennine what, if any, measures might be necessary to limit individual exposure to that radioactivity.
RADIOLOGICAL CHARACTERIZATION ON A COARSE GRID During *the period November 1993 - January 1994, Dames & Moore perfonned measurements of gamma radiation and sampled the surface and near surface soils at 44 locations in the 1,000-acre area between the western boundary of the WNYNSC and cattaraugus Creek, as shown on Figure 52. The survey confirmed the location of the WNYNSC Off-Sile Radiatioa Invesaiptioa S-2 December I, 1995
I .
elevated areas of Cs-137 shown on aerial survey reports and identified a smaller area of approximately 46.5 acres near the WNYNSC boundary for more extensive evaluation.
RADIOWGICAL CHARACTERIZATION ON A FINE GRID A Fine Grid Investigatiori (FGI) was defined to evaluate the magnitude, deposition patterns, and extent of radioactive material in the study area in greater detail. Field survey efforts were focused on the area of elevated Cs-137 radioactivity deposit identified in the coarse grid survey.
The initial FGI study area consisted of approximately 46.5 acres. Of this total; 5.2 acres were classified as disturbed by human activity or use: 2.3 acres of active farmland with tilled fields; 0.8 acres around a residence area consisting of one house and two trailers/mobile homes; and three areas totaling 2.1 acres used for the storage of derelict vehicles and bulk items. The other 41.3 acres in the initial study area were classified as undisturbed by human use and consisted of native woodlands. A review of historical
- maps and aerial photographs indicates that these areas have been undisturbed since 1968.
The components of the survey included
- An .evaluation of soil samples from grid blocks with a variety of terrain and ground cover to provide an indication of horizontal deposition and vertical penetration of the Cs-137, and to provide confidence on the ntagnitude of variability.
- A systematic measurement of Cs-'137 gamma radiation at eight fixed points in 10 m x 10 m grids to provide a determination of soil activity averaged over the areas.
WNYNSC Off-Site Radiation Invemgation S-3 December l, 1995
- A systematic measurement of total gamma radiation at eight fixed points in each 10 m x 10 m grid, to provide a determination of radiation dose rate averaged over the areas.
- A measurement of Cs-137 gamma radiation dliring a serpentine walkover of each 10 m x 10 m grid between the eight fixed points of the systematic measurements, provided 1009' coverage of accessible areas to ensure that anomalous point sources of radioactive material concentration would not be overlooked.
During the period July 1994 - September 1995, Dames&. Moore pcrfonned the FGI.
The survey data set consists of over 35,000 instrument readings in three modes and analysis of over 200 soil samples. The surface area surveyed contained over 1500, 10 m x 10 m grids in the 46-acre focus area. Levels of Cs-137 concentration in the surface layer 'of soil based on the activity inferred from instrument readings averaged in each 10 m x 10 m grid are shown in Figure S3 and ranged from 3.3 +/- 1.4 pCi/g in
- disturbed areas to 34, 7 +/- 8.2 pCi/g in the undisturbed woodlands.
Where the surface area had been disturbed by cultural impacts, radiation from the C.S-137 was only slightly distinguishable from ambient gamma radiation background. Within the undisturbed woodlands, this survey delineated an area with statistically elevated Cs-137, similar to the area jdentified in the aerial survey of 1984, as displayed in Figure S4.
Soil sampling at locations in the study area indicated that Cs-137 activity is associated with the organic humus layer on the ground surface. In the study region, this surface layer is approximately 2*-4* (5-10 cm) thick, lying on more impermeable clay below.
Soil radioactivity analysis indicated a variable local distribution of the observed activity; the Cs-137 concentration might_ vary by a factor of 2 to 3 within a meter or two horizontal displacement. This variation appeared to be due to local surface effects, (e.g.
WNYNSC Off-Site IUdiatioa Investiprion S-4 ~ber 1, 1995
driplines from trees and limited variations in thickness of the humus), rather than isolated particles of higher activity.
Walkover surface scans in the FGI identified 29 !Om x !Om grids where the peak count rate observed in one quarter of the grid was considered anomalous, greater than three times the average count rate in that grid. Detailed surveys of these grids demonstrated that hot particles were not present.
The gamma radiation dose *rate survey results indicated that there were localiu:d regions in the study area in which the dose rate averaged over an area of 50m x 50m, was 1.2 to 1.5 microremlhour greater than the ambient background of 3. 7 microrem/hour. This level of external gamma radiation dose rate is within the variation of dose rate reported around the WNYNSC by previous aerial surveys (EG&G, 1991).
The local variations in soil radioactivity appeared within the* broad gaussian pattern of deposition from an airborne plume; qn a large scale, the Cs-137 concentration decreased
- with distance from the peak value along the central radial, and it decreased with distance away from the central radial of the deposit. Local terrain and surface characteristics had minor influence on the gaussian pattern. The contours of the Cs-137 soil concentration from this survey are compared to the contours of the previous aerial survey in Figure S4.
The deposition area is consistently located by the two surveys, within the uncertainties associated with each of the surveys.
OOSE ASSFSSMENT The dose assessment for the WNYNSC Off-Site Radiation Investigation was performed to determine a potential radiation dose to an individual in the FGI study area due to the concentration of radioactive Cs-137 in the soil. The dose assessment process uses the 95 % confidence level of the average activity in the soil (inferred from . instrument readings of gamma radiation at the ground surface), along with conservative assumptions WNYNSC Off-Site Radiation Investigation S-5 .December I, 1995
on individual exposure and_ land u5es, to develop an estimate of the potential dose to an individual through the computer modeling code, RESRAD (DOE, 1993). The RESRAD code is an analytical tool for modeling environmental transport of residual radioactivity in the soil. The code is recognized and used in analysis and comparative studies by both the NRC and the EPA. Additionally, the code enables the calculation of potential doses to individuals when appropriate exposure parameters are provided.
Plausible scenarios of current and future land use were identified, using actual land use data and standard scenarios described by the NRC and the EPA. The four land use scenarios that were evaluated included:
(1) Realistic current Use - Standard Scenario: Residem-Farmer Scenario. The site is used for residential and subsistence farming. Exposure pathways include external radiation, inhalation and ingestion of radioactive material.*
(2) Realistic Current Use - Modified Scenario: HUlller-Camper. The use of the undisturbed woodJands is for recreation purposes, primarily hunting in season, and the cutting and collection of firewood. This use of the land will be evaluated using the outside direct exposure pathway, to obtain the dose for each 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> spent in the woods.
(3) Conservative Current Use - Modified Scenario: Residenl -Homeworker. One property in the FGI area included one pennanent residence and l'Ro occupied
- house trailers. In addition to undisturbed woods, there were several acres of land cleared and used for the storage of derelict vehicles. The owner/resident operates a home auto mechanic shop on .the site in the permanent building with residence quarters over the repair shop. This use of the land will be evaluated using the residenl-farmer standard scenario, to account for extra time on site, since the occupational location is on the site just as in the resident-farmer scenario.
WNYNSC Off-Site Radiation Investigation S-6 December 1, 1995
L (4) Conservative Future* Use - Modified Scenario: Residenc~-Trailer. A plausible future use of the woodlands is that a residence could be built in an undisturbed area, leaving some of the radioactivity among the undisturbed trees in* the vicinity of the yard. The residential use least disruptive to the surface deposit of Cs-137 would involve a trailer home rather than a conventional fixed structure..In this case, the trailer home is placed on 0.6 acres (50 m x 50 m) of cleared and leveled land, but the resident can spend some time outdoors in the undisturbed woods where the radioactivity remains on the surface. For this future use scenario, the observed characteristics of disturbed locations in the Off-site area were used to conservatively apply realistic site preparation activities to the thin layer of surface contamination.
Values of the critical scenario parameters and corresponding doses are summarized in Table S-1. Upper bound doses, calculated with the RESRAD environmental transport and dosimetry computer code, indicated that:
- In current land uses, potential annual doses for the maximally exposed individual are below 5 mrem in the current year.
In future land uses, the most conservative scenario assumption (i.e., the scenario in which a residence house trailer is located in the highest 0.6 acre area of the contamination contours) results in a projected annual dose to the maximally exposed individual below 8 mrem in the current year.
Due to the radioactive decay of Cs-137 with a half-life of 30.2 years, annual doses in subsequent years will naturally decrease by 2.2 percent each year.
WNYNSC Off-Site Radiation Investiptioo S-7 December l, 1995
Table Sl Table Sla Summary or Parameters Used in Scenario Modellil&
Resident- Hunter- Resident- Residence-Puamet.er Fumec 1 Campcrl Homeworker 3 Trailer' Cs-137 soil layer thickness (m) 0.3 0.075 0.15 . 0.3 es-13'7 Activity (pCi/I) 1.0 21 3 1.8 Transmission to Indoors' 67'5 - 109' 80" Time Indoon SS" 05' S5ti S5'5 Time Outdoors 21 '5 1.145' 6 21 '5 219
Diet from oa site Vegeeables. fruit, pain 505' o" 09' 09' Milk 100$ 09' o" 09' Meat and Aquatic foods 509' Oti 09' Oti Drinking water 1005' 09' 1009' 1009' Groundwater frllctiaa 100'5 0'5 1005' lOO!i Table Slb Summary of Doses by Pathway for Reference Expo.sure Scenarios Doses by Pathway Resident- Hunter- R.csideat- Residence-(mrcm. per year) . Farmer 1 Camperl Homeworker 3 Trailer' Ground Direct Inside 1.87 - 1.0 3.9 Ground Direct Outside 1.06 0.73 3.8 4.1 9 Inhalation 0 0 0 0 Plmt foods O.ll6 - - -
Meat Foods 0.07 - - -
Milk from site 0.04 - - -
Drinkin& Water 0 - 0 0 Soil Ingestion 0 0 0 0 TO(&J Do6c in First Year 3.10 0.73 7 4.8 8.0 Notes: *-* the pathway is not put of the scawio 6 1.149' of year = 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br />
- o* cakulated dOGe ~ 0.01 mremiyr 7 Tot,al Dose for each 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> spent in 1 US NRC stao.dard evaluation sceaario the undisturbed woods 2 Realistic scenario, current and future 8 Time outdoors apportioned to 17 9' in use of undisturbed woods cleaml land and 4" in undisturbed woods 3 Conservative scenario, current use 9 Sum of l.S mmu while in cleared land 4 Conservative acenario, future use and 2.6 mrem while in undisturbed woods S Shielcfini of inhabitants by building WNYNSC Off-Site Radiation Investigation S~8 December 1, 199S
L CONCLUSION The WNYNSC Off-Site Radiation Investigation was performed in phases of field sampling, measurement and analysis. The observations and survey results discussed in this summary indicate that the area of deposited Cs-137 was adequately bounded and quantified by the survey procedures used. The instrument measurements provided a valid representation of the surface deposition that made more extensive sampling and laboratory analysis unnecessary. Eight readings in each lOm x lOm grid provided an indication of the average and 95th percentile Cs-137 activity to meet the characterization and interpretation requirements identified in the NRC manual NUREG-5849 (NRC, 1992).
The dose assessment indicates that, under current and future land uses, conservative assumptions on personal exposure result in a projected annual dose to the maximally exposed individual below 8 mrem in the current year. The calculated upper bound doses are in the range of doses suggested by proposed federal decommissioning criteria (15 mrem per year) and state guidance (10 mrem per year) as discussed in Section 2 (EPA,
- 1994; NRC, 1994; NYSDEC, 1993). The doses are considerably below the 100 mrem per year dose limit reeommended by the NCRP (NCRP, 1987a) and arc only a small fraction of the average annual effective dose equivalent to a member of the U.S.
population, 295 mrem per year (NCRP, 1987).
REFERENCF.S DOE 1993 U.S. Department of Energy, *Manual For Implementing Residual
'Radioactive Material Guidelines Using RFSRAD,
- Version 5.05.
September 1993.
EG&G 1981 U.S. DOE Remote Sensing Laboratory, *A Comparison of Aerial Radiological Survey Results of the Nuclear Fuel Services (NFS) and Surrounding Area.* Report EG&G # EP-FOOl. June 1981.
EG&G 1991 U.S. DOE Remote Sensing Laboratory, *An Aerial Radiological Survey of the West Valley Demonstration Project and Surrounding Area.*
Report EGG-10617-1080, September 1991. [This 1991 report presents the results of the aerial survey conducted in Aug-Sep 1984].
WNYNSC Off-Site Radiation Investigation S-9 Docembel' 1, 1995
EPA 1994 U.S. Environmental Protection Agency, *Technical Summary Report Supporting the Development of Standards for the aeanup of Radioactively Contaminated Sites (DRA.FI1.~ Washington, DC, April 1994.
NCRP 1987 National Council on Radiation Protection and Measurements, *Ionizing Radiation Exposure of the Population of the United States,* NCRP Report No. 93, Washington, DC, 1987.
NFS 1968 Nuclear Fuel Services, Inc., *A Study of Particulate Release Rate During the Period March 8-10, 1968," West Valley, NY, March 24, 1968.
NRC 1992 U.S. Nuclear Regulatory* Commission, *Manual for Conducting Radiological Surveys in Support of License Termination (DRAFT),"
Report NUREG/CR-5849, 1992.
NRC 1994 U.S. Nuclear Regulatory Commission, *Radiological Criteria for Decommissioning - Proposed Rule," Federal Register, August 22, 1994, Part m: pages 43200-43232.
NYSDEC 1993 NYS Department of Environmental Conservation, *Technical Administrative Guidance Memorandum No 4003,
Subject:
Cleanup Guidelines for Soils contaminated with Radioactive Materials.*
September 14, 1993.
WNYNSC Off-Site Radiation Jnvestiptioa S-10 Dcccmber l, 1995
( (
9 Explanation
- 15.4 Conloun lrom 1984 tlyo*er 1ur.,.p by EG&G.
1 15.1 Mop source ls lhe Town ol A*hlord
"' To* Mop. Properly lln** and other lealurH were dlglllud by mean* of 27.1 ~ computer aided drafting .
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23.1 J 21 Figure S 1 Cs-Prong as Defined by I 1984 flyover Survey l..----------------------~----------------------~--------------------------------.l!!"!:;=D=A;M=E=S~&;;;;;~M~O=O=R=~i_....:..;Ap~r~ll-3~,_.:.:19~9~~--.J
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--*.!_!!le II Explanation Actual *Sample Locallons 11.t
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. Map eourc* 11 lh* Town of A1hlord Ta* Map. Properlr llnH and olhor f*ah1r** **** dlglllzed by m*uns ol compuler aided dralllng.
Sc*le In feel tZ'\iq3 o 100200 400 eoo Figure S2 Scale in meter* Actual Sample Locations I ____
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- DAMES & MOORE Janua
EXPLANATION 0 pCl/9
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li ne of suNeyed areo Figure S3 Contours of Average Cs-137 Concentrations {pCi/ g)
SCALE: Grid cells are 50m X 50m
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- DAMES I< MOORE
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(/l EXPLANATION lS ,,O/t 20 ,cJ/1 Plum* contou" from 15 pCl/1 198' otrial survey (EG.tG. 1991 )
10 ,cl/t 0 llCl/t lln* of surveyed area t
l Figure S4 Comparison of Ground Surveyed and Aerial Surveyed CS-137 Concentrations I SCALE: Grid cells are 50m X 50m I
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- DAMES I< MOORE