ML20127K673
| ML20127K673 | |
| Person / Time | |
|---|---|
| Site: | Pilgrim |
| Issue date: | 12/31/1992 |
| From: | BOSTON EDISON CO. |
| To: | |
| Shared Package | |
| ML20127K659 | List: |
| References | |
| NUDOCS 9301260185 | |
| Download: ML20127K673 (41) | |
Text
{{#Wiki_filter:. . . . . . 1 i PROPOSED RELOCATION AND PLACEMENT OF CONSTRUCTION SOIL CONTAINING TRACES OF RESIDUAL RADICACTIVITY FROM THE PILGRIM NUCLEAR POWER STATION DECEMBER 1992 I 9301260185 930115 PDR ADOCK 05000293 PDR p \
i i i ; 1 i . ! Table of Contents i i 1.0 Introduction l 2.0 Description of the Waste Streams i j 2.1 Waste Stream Generation i 2.2 Chemical Characteristics i 2.3 Radioactive Material Characteristics l 3.0 Proposed Disposal Method 3.1 Description of Proposed Disposal Area
; 3.2 Description of Disposal Method i
3.3 Description of Controls l 3.4 Compliance With Regulations 4 j 4.0 Radiological Assessment 4.1 Doses to a Maximally Exposed Member of the Public ! 4.2 Doses to an Inadvertent Intruder l 4.3 Doses to Workers l 4.4 Dose From Recycling 5.0 Conclusion 4 Attachment I Calculations i Attachment II References l Attachment III Figures i ? 4 ) 4 J i
l l J l 1.0 Introduction j Boston Edison Company (BECo) requests approval, pursugnt to 1 10CFR20.302(a), to dispose of approximately 79,000 ft (2238 m3 )
- of sand, silt and rough stone containing very low levels of
- radioactivity. This material is located on BEco-owned property near the Pilgrim Nuclear Power Station (PNPS).
I PNPS is a General Electric Boiling Water Reactor, 670 MWe capacity. PNPS began commercial operation in December 1972, and . its current license expires in 2012. PNPS is located on a 517 l j acre site owned by BECo in Plymouth County on the western front l of Cape Cod Bay in Massachusetts. The PNPS updated Final Safety l 1 Analysis Report, Chapter 2.0, PNPS Unit 2 Preliminary Site Analysis Report and Unit 2 Environmental Report, September 1976, provide site characteristics and site-specific information , applicable to and used in the assessment of radiological and environmental impact of the proposed disposal methods.
- This report provides an assessment of the material considered for i disposal, BECo's proposed alternative disposal method under the
- provisions of 100FR20.302(a), and an assessment of the radiological and environmental impact of the proposed disposal 4
method. NRC guidance from NUREG 1101, "0nsite Disposal of Radioactive Waste" (Reference 1), has been considered in ] developing this report. The onsite disposal of the contaminated
; material will eliminate the temporary storage area currently j being used to allow the construction of a new office building and
- a possible future interim low-level radioactive waste storage
- location.
2.0 Descrintion of the Waste Streams The contaginated gaterial for disposal consists of approximately 1 79,000 ft (2238m ) of controlled backfill grading soil placed j during original plant construction. This material is contaminated with very low levels of radioactivity. The mass of 1 this material has been estimated to be 4.0 million kilograms. The contaminated material was moved to its current location in' August 1988 to locate it further away from wetland areas. During the move, the total volume of material was determined by multiplying the number of truck loads by the volume of each load. Four projects contributed to the majority of.the material: (1) installation of a third diesel generator; (2) 10CFR50 Appendix R fire protection modifications; (3) excavation of the foundation
. of the hydrogen water chemistry injection building; and (4) physical security modifications.
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t t i 4 2.1 Waste Stream Generation } This material was contaminated by several events involving releases of radioactive materials to onsite locations where excavations were subsequently made. These events were previously 1 reported to or inspected by the NRC. Examples of these events include the June 11, 1982 Resin Egress Event (Reference 2), the i Radwaste Trucklock Spills (References 3 and 4) and the Spill from j the Cordensate Demineralizer Resin Addition Room (Reference 5). ) 2.2 Chemical Characteristics j The material contains sand, silt, and rough stone (concrete ! rubble). I- is collectively considered as soil and exhibits soil j characteris.ics. There are no chemical compounds or hazardous materials rr xed in the soil. j 2.3 Radioactive h'terial Characteristics 4 i When the material was moved to its present location (Figure 1), i samples were col ected and analyzed by gamma spectrometry. Two i radionuclides, Ct 60 and Cs-137, were identified that could be
- attributed to the meration of PNPS. Because residual Cs-137 is i commonly found in the environment due to weapons testing, Co-60 j is the only radionuclide that is directly attributable to station operation. The presence of Cs-134 in the soil along with Cs-137 i would confirm that at least some fraction of the total Cs-137 i
radioactivity was directly attributable to PNPS; however, no Cs-134 was identified. Nevertheless, for conservatism, the Cs-137 , activity is included in the total activity. I i The average gross Co-60 concentration is approximately 48 pCi/kg. l The average, gross Cs-137 concentration is approximately 110 i pCi/kg. Assuming the mass of the pile is 4.0 million kilograms, ! the estimated total Co-60 activity is 194 uti and the Cs-137 j activity is 442 uti. i a 4
3.0 PROPOSED DISPOSAL METHOD Onsite disposal of the contaminated material is proposed because the activity is low and the geological and hydrological considerations of the proposed disposal area will cause no adverse environmental impact. 3.1 Description of Proposed Disposal Area The material for disposal will be placed approximately 1200 ft. south west of the plant in an area between the off Gas Stack access road, and the main parking lot access road within the PNPS owner controlled area (Figure 1). This area was selected for reasons described below. The surface stratum in the disposal area consists of approximately 20 feet of silt-like and clay-like fine sands with scattered boulders. The stratum is moderately compact. The soils underlying the upper stratum are moderately compact to compact, poorly to well graded sands with some gravel and cobbles. Boulders are scattered throughout the overburden soil, and a discontinuous thin layer of small boulders overlies bedrock. Bedrock is approximately 60 to 70 feet below mean sea level. There are no known faults at or near the station site. The proposed storage area is a natural depression in the ground (kettle). Surface drainage will be minimized by capping with topsoil and seeding. Any remaining surface runoff will be entirely within BEco property. The material will be placed and graded to follow existing contours of the area. After placement, the surface will vary from three to as much as seven feet above the current height. The disposal location is approximately 150 ft. from the nearest wetland, shown as W-ll on Figure 1, and approxime.tely 1000 to 1500 ft. from Cape Cod Bay. The area within 2 miles of the site is sparsely developed with the exception of the seasonal population along Priscilla Beach and White Horse Beach. The closest Plymouth Town water supply source is 2 3/4 miles from the site and there is no current or proposed ground water development in the vicinity of the site. Residents within a 2 1/2 mile radius of the site receive water from the town supply with three known exceptions. These exceptions, which operate their own wells are:
- a. Approximately 1 mile southwest of the site. This well is at a former commercial boat yard. This well is not currently in use.
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- b. Approximately 1 1/2 miles southwest of the site. This well is used for irrigation of a golf course.
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1 1 c. Adjacent to southern site boundary. This well is l occasionally used to irrigate a cranberry bog. )i These wells are shown on Figure 2. i The site is located in a coastal ground water basin; the landward edge of the basin coincides ap3roximately with the surface water l
- drainage divide located less taan one mile southwest of the site. '
The source of ground water within the basin is entirely from rainfall and snowmelt on the basin. The aquifer at the site a consists of approximately 90 feet of glacial till and outwash I with permeability of 300 to 400 gallons per day per square foot. i The lower 70 to 80 feet of. the aquifer is saturated. The aquifer is underlain by relatively impervious bedrock. ! The site ground water table has a moderately steep gradient with j flow toward the northeast to Cape Cod Bay. All of the wells are to the south or southeast. The regional ground water profile and
- drainage basin are shown on Figure 3.
1 l 3.2 Description of Disposal Method ; i i The material for disposal will be placed in the trenched ground and will be compacted. After piscement and compacting, topsoil j and conservation mix grass seeding will be placed to help prevent i erosion. The topsoil and seeding will minimize the surface i drainage. Any remaining drainage and surface runoff will be entirely within the BEco owner controlled area. l 3.3 Description of Controls i The area is not planned and will not be available for public use, i Upon completing the disposal, no active controls will be employed l since the area is-within the BEco PNPS owner controlled area. 3.4 Compliance with Regulations . ) The proposed disposal of the contaminated material at the i location does not require approvals from local, state or other agencies other than the Nuclear Regulatory Commission. The proposed disposal method is intended to comply with NRC guidance [ Reference 1]. t
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1 j 4.0 Radioloaical Asseninent 1 1 Potential pathways of exposure were reviewed for the disposal of ! the contaminated material. The pathways reviewed included direct j exposure to radiation from the dirt pile, consumption of j radioactivity from its incorporation into drinking water or food i grown on the disposal site following hypothetical release of the
- site after decommissioning, and radionuclide migration in
! groundwater to Cape Cod Bay. 1 i 4.1 Doses to a Maximally Exposed Member of the Public ! ! The material for disposal will be placed approximately 1200 ft. I south west of the plant in an area between the Off Gas Stack )
- access road, and the main parking lot access road within the PNPS
- owner controlled area (Figure 1). The calculated whole body dose i from external- exposure to an individual who walks by the disposal
! site, to and from the shorefront, every day for a year is 0.025 . mrem. Radioactivity values for 1992 are assumed. Internal dose to any individual from the dirt pile for the time j period 1992 to 2017 is expected to be zero because the disposal 3 lccation is onsite and it cannot be used for growing i fruits / vegetables for consumption or for operating a drinking j water well during this time period. i i Currently, no residential wells exist in the area and the time it i j would take for the radionuclides in groundwater to reach Cape Cod
- Bay was calculated to be approximately 136 years- for Co 60 and 109 years for Cs-137. This would ensure nearly complete decay of i the radioactivity.
j 4.2. Doses to an inadvertent Intruder The 1991 decommissioning plan for PNPS 1 gives a value of 56 months as the shortest time frame in which the site could be i i . released for unrestricted use after license expiration in 2012.~
- Therefore, the following doses were calculated using decayed l radioactivity values for 2017.
In 2017, an intruder and his family are assumed to be living on i the disposal site year-round. They consume vegetables grown on the site and drink water from a well they drilled on the site. ! The highest internal whole body dose calculated was 0.174 mrem to the adult. The highest organ dose calculated was 0.577 mrem to the child bone. ! The calculated whole body dose frcm external exposure to an
- individual who resides on the disposal site for 8,760 hours in.
- 2017 is 0.512 mrem.
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1 i i ) 4.3. Doses to Workers I The whole body dose from external exposure to the material was
! calculated for a radiation worker involved in moving the dirt to ! the disposal site. An exposure period of 200 hours was assumed l and the resulting dose is 0.0503 mrem.
Internal dose due to intake of re-suspended radioactivity was J calculated as 0.149 mrem to the lung. This calculation is conservative in that it assumes the worker breathes all of the
- re-suspended radioactivity and that no measures are taken to minimize dust generation.
l l In order to minimize dust generation during the transfer, the j dirt will be sprayed with water prior to disruption. This procedure will be repeated as dry dirt becomes exposed. j 4.4. Dose from Recycling j The material will not be recycled; therefore, no analysis was j performed for this pathway. i l < i l i
, - - - - , . ,. _ w . - . , . . - , . . .. a ,. . - , - - . _ _ . . , , . - , - , - _ - . .
a 4 i I . . 9 1 ! i ? 5.0 Conclusion Contaminated material to be disposed onsite at PNPS does not constitute a hazard to either the plant employees, general public, or the environment. BECo requests approval to dispose of the material described in this application as submitted. 1 I I I I I I i d I~ l-i I t I l I
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Boston Edison Company Application For Approval For Onsite Disposal Of Slightly Contaminated Soil -- Attachment I CALCULATIONS _ _ _ - __._________-u_m--_ _ _ _.m_.._w_ -c-_-__.-. _
- .- .. .- -_ -. -. .- - - .- -. ~.-
4 i i ! I. AVERAGE CONCENTRATION AND TOTAL ACTIVITY OF C0-60 AND CS-137 The contaminated material was collected at the present location in two separate intervals. For the original pile, we performed a weighted i average of reported radionuclide concentration values for 24 " Buckets" j (at 3 yds. per bucket), 66 small (10 yds.) and 69 large (16 yds.) ! truckloads. Approximately 160 yds, of asphalt will be removed upon i transfer of the contaminated material that will leave 1676 yds. of i material. The total mass remaining was recorded as 2.3 million kilograms (based on a density of 1.8 g/cc for the original pile). l A second pile was added to the original pile. This was sampled in-situ
- and 13 samples were obtained. This pile was then transferred to the
- site of the original pile and has an estimated volume of 1300 yds.
! About 50 yds. of asphalt is present in this second pile. The asphalt j will be removed, leaving 1250 yds. of contaminated material. Using the i density of 1.8 g/cc, its mass is approximately 1.7 million kilograms. i l The total mass of the two piles is approximately 4.0 million kilograms. 1 i The radioactivity content of the material was determined by weighted i averaging of the samples obtained per truckload for the first pile and
, of the 13 samples from the second pile. For the purpose of weighted j averaging, the concentration stated was used and the Minimum Detectable
- Concentratior (MDC) value was included for isotopes reported as "< MDC."
i i The radioactivity values for the 159 samples' weighted average from the i original pile were decayed from May 1988 to October 1992 (4.42 years). ! The radioactivity values for the new pile were decayed from July to October 1992 (0.25 years) in computing their weighted average. j The two weighted averages were summed as one weighted average. I
- The weighted average of the 4.0 million kilograms of material is
i Isotone Concentration Activity Cs-137 109.7 pCi/kg 442 uCi. l Co-60 48.3 pCi/kg 194 uCi. l 1 : t 0 k 1
II. GROUND PLANE (DIRECT) DOSE RATE Assumptions:
- 1. The source is uniformly distributed and infinitely thick.
- 2. Dose rate conversion factors are interpolated from Reference 8, Table 2, for 0.662 Mev (Cs-137) and 1.25 Mev (Co-60) photons at a depth of 60 cm.
Cs-137 concentration x Cs-137 dose rate: 109.7 pCi x kg x 1.8q x 0.037 Bq x 1.12 E-3 Gy/yr = 8.18E-6Gy kg 1000g cc pCi Bq/cc yr Co-60 concentration x Co-60 dose rate: 48.3 x 1 x 1.8 x 0.037 x 4.32E-3 = 1.39E-5Gy 1000 yr Total - 2.21E-5Gy/yr
= 2.2 mrem /yr An individual who walks by or stands near this pile 15 minutes per day (-100 h/ year) will get a dose lof:
100 hr/yr x 2.2 mrem /yr = 0.025 mrem /yr 8760 hr/yr i l m
2 III. RADIONUCLIDE MIGRATION IN GROUNDWATER Assumptions:
- 1. Density of soil is 1.8 g/cc as used in Reference 6.
- 2. Equations and data taken from Reference 7, Chapter 4.
- 3. Kd values for Co-60 and Cs-137 from ANL/ES-160 are 100 cc/g and 80 cc/g, respectively.
- 4. Gradient was determined by elevation above MSL divided by distance to Cape Cod Bay.
Gradient = 90 ft = 0.09 ft/ft 1000 ft MSL = Mean Sea Level
- 5. For purposes of this calculation the soil category is medium sand.
Travel Time = t = x Rd [eq. 4.46] U where, x = distance to Cape Cod Bay = 1000 ft (1000 ft - 1500 ft range) U = yx = Pore velocity in cm/s [eq 4.8a] = K dj/Ne Ne AX Rd = 1 + Pb Kd = Retardation Coefficient (unitiess) Ne K = hydraulic conductivity = 1.42 E-2 cm/s (medium sand) Pb = density = 1.8 g/cc Kd - distribution coefficient = 100 cc/g for Co-60 Ne = effective porosity = 0.32 (medium sand) Rd = 1 + (1.8 o/cc)(100 cc/gl - 563.5 [eq 4.14] ' O.32 0 = (1.42E-2 cm/s)(0.09 ft/ft) = 3.99E-3 cm/s 0.32 Substitute values into travel time equation: ; t = (1000 ft)(30.5 cm/ft)(563.5) = 4.30E 9 sec. ) (3.99E-3 cm/s) t = 136.4 years 1 For Co-60, 1364 years is equal to 26 half-lives; for Cs-137, Rd=451 and t=109.17 years or 3.62 half lives.
4 IV. TOTAL BODY AND ORGAN DOSE TO AN INDIVIDUAL Assumptions:
- 1. The year is 2017, the time when the current Decommissioning Plan allows " free release" of the site.
- 2. The concentration in soil is affected by radioactive decay only (i.e., no movement of soil downward or outward from original position). For C0-60 the concentration in 2017 will be 1.78 pCi/kg and Cs-137 will be 61.8 pCi/kg.
- 3. Values for consumption of vegetables, fruits, and grains for adults, teens, and children taken from Reference 6.
- 4. Values for plant uptake of radionuclides from soil taken from Reference 6.
- 5. Values for mrem per pCi ingested for adults, teens, and children taken from Reference 6.
The equation used to calculate dose from ingestion of foodstuffs grown on the dirt pile is: mrem /yr - (Csoil)(Biv)(Vap)(DFingest) where, Csoil - concentration in soil for radionuclide of interest in pCi/kg. Biv - Stable element transfer value (from soil to plants) [ Reference 6, Table E-1) for radionuclide of interest. Vap = Usage factor (food consumption) in kg/yr [ Reference 6, Table E-5]. Foods specified in this calc. are fruits, veg., grains and leafy veg. Values are: Adult: 584 kg/yr Teen: 672 kg/yr Child: 546 kg/yr DFingest - Ingestion dose factors for radionuclide of interest [ Reference 6, Table E-11,12,13]. Units are mrem /pCi ingested.
Results for ingestion of vegetables and fruit in 2017 (mrem /yr): Adult Bone Liver T. Body Thyroid Kidney Lung GI-LLI Co-60 No Data 2.09E-5 4.61E-5 No Data No Data No Data 3.93E-4 Cs-137 2.88E-2 3.93E-2 2.58E-2 No Data 1.34E-2 4.44E-3 7.62E-4 Total 2.88E-2 3.94E-2 2.58E-2 No Data 1.34E-2 4.44E-3 1.15E-3 Teen Co-60 No Data 3.15E-5 7.09E-5 No Data No Data No Data 4.10E-4 Cs-137 4.65E-2 6.18E-2 2.15E-2 No Data 2.10E-2 8.18E-3 8.80E Total 4.65E-2 6.18E-2 2.16E-2 No Data 2.10E-2 8.18E-3 1.29E-3 Child Co-60 No Data 4.83E-5 1.43E-4 No Data No' Data No Data 2.68E-4 Cs-137 1.10E-1 1.06E-1 1.56E-2 No Data 3.44E-2 1.24E-2 6.61E-4 Total 1.10E-1 1.06E-1 1.57E-2 No Data 3.44E-2 1.24E-2 9.29E-4 Total Body maximum for adult is 2.58E-2 mrem /yr. Organ maximum for child. bone is 1.10E-1 mrem /yr. l i l l
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V. DOSE TO AN INADVERTENT INTRUDER I i Assumptions: ] 1. Methodology used is to take 25% of a year's rainfall mixed with a plume of 1000 foot radius.
- only radioactive decay removes activity from soil over the time period from when pile is relocated to when well is made operable; i j no groundwater removal or dispersion.
l - entire activity mixes with 25% of average annual precipitation for j a 1,000 foot radius of the well, f 2. Volume of dirt pile is 79,008ft 3, ! 3. Total 00-60 activity in year 2017 is 7.16E6 pCi. Total Cs-137 - g activity in year 2017-is 2.49E8 pCi.
! 4. Annual precipitation is 46 inches (from PNPS FSAR-Table 2.3-16).
I i
- 5. Adult consumes 730 1/yr of water and, teen and child consume 510
! 1/yr of water [ Reference 6, Table E-5]. 9 ! 6. Ingestion dose factors for radionuclide of interest [ Reference 6, l Tables E-11, 12, 13]. I i l 7. Intruder drills a well and begins consuming water in 2017. i j _GA l culate volume of water: l A = nr 2 i A = x(1000 ft)2 l A = 3.14E6 ft2 i i
- 25% of 46 inches is 11.5 inches : 12 inches': 1. ft l V = 3.?4E6 ft2 x 1 ft x 28.32 1/ft3 - 8.89E7 1 l
l- Calculate the a:tivity concentrations: ! h -60 7.16E6 pCi = 8.06E-2 pCi/l
- 8.89E7 1 Cs-137 2.49E8 oCi = 2.76 pCi/l l
8.89E7 1 i [~ e-r , . , - . - _ . - - - - . ~ . . - - . . _ . , , - . _ , , , , . , , . . . . , , . - . , , _ , - . _ -
Calculate activity intake f one year: Adult Co-60 (8.06E-2 pCi/1)(730 1) - 5.89El pCi Cs-137 (2.80 pCi/1)(730 1) - 2.04E3 pCi ' Teen / Child Co-60 (8.06E-2 pC1/1)(510 1) - 4.llEl pCi Cs-137 (2.80 pCi/1)(510 1) - 1.43E3 pCi Calculate dose resultina from drinkina water from well: mrem /yr - activity intake x ingestion dose factor Adult TB Co-60 (5.89El pCi)(4'.72E-6-mrem /pci) - 2.77E-4 a, rem /yr .
+ Cs-137 (2.04E3 pCi)(7.14E-5 mrem /pci) - 1.45E-1 mrem /vr 1.49E-1 mrem /yr Teen / Co-60 (4.11El pC1)(No date) - No data Child Bone Cs-137 (1.43E3 pC1)(3.27E-4 arem/pC1) - 4.67E-1 mrem /vr
- 4.67E-1 mrem /yr '
l l l [ i l_.. .. - -. .. . _ -. .. .- , .. .. .....,.,,:.,,.-_.....--.- . ,,,.- , ,,
4 f 1 i i VI. WHOLE BODY AND ANY BODY ORGAN DOSE TO AN INADVERTENT INTRUDER A. Sum the dose from vegetable and well water consumption: i i Fruit & Vegetable + Drinking Water - Total ) Adult 2.58E-2 + 1.49E-1 - 1.74E-1 mrem /yr TB Child Bone 1.10E-1 + 4.67E-1 - 5.77E-1 mrem /yr B. Ground Plane (Direct) Dose Rate Assumptions:
- 1. The source is uniformly distributed and infinitely thick.
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- 2. Dose rate conversion factors are interpolated from Reference 8, Table 2, for 0.662 Mev (Cs-137) and 1.25 Mev (Co-60) photons at a depth of 60 cm.
Cs-137 concentration x Cs-137 dose rate: j 61.8 oCi x kg x lagg x 0.037 Ba x 1.12E-3 Gv/vr - 4.61E-6Gy kg 1000g cc pCi Bq/cc yr 4 Co-60 concentration x Co-60 dose rate: . 1.78 x 1 x 1.8 x 0.037~ x 4.32E-3 - 5.12E-7Gy 1000 i yr Total - 5.12E-6Gy/yr
- - 0.512 mrem //r i
l J 4 f r
VII. DOSE TO WORKERS Assumptions:
- 1. It is conceivable that some resuspension of radiogctivity (dust) could occur during the relocation of the dirt pile. The resuspension factor is 10 . (from NUREG 1400).
- 2. The hypothetical individual is involved with the relocation of every truckload of dirt.
- 3. The total activity in the pile is:
Co-60 = 1.94E8 pCi (1992 value) Cs-137 = 4.42E8 pCi (1992 value) 1
- 4. Dose conversion factors are taken from Reference 6, Table E-7.
- 5. The age category -involved for purposes of dose assessment is " ADULT". (No teenagers or children employed as radiation workers).
- 6. The individual inhales all of the resuspended radioactivity.
Activity of each radionuclide inhaled Co-60 (1.94E8 pCi)(10-6) = 1.94E2 pCi Cs-137 (4.42E8 pCi)(10-6) = 4.42E2 pCi Internal Dose Assessment (mrem): Bone Liver T. Body Thyroid Kidney Lung GI-LLI Co-60 No Data 2.80E-4 3.59E-4 No Data No Data 1.45E-1 6.93E-3 Cs-137 2.64E-2 3.42E-2 2.36E-2 No Data 1.23E-2 4.15E-3 4 63E-4 Total 2.64E-2 3.46E-2 2.40E-2 No Data 1.23E-2 1.49E-1 4.64E-3 Organ receiving highest dose is the lung at 1.49E-1 mrem total.
i i Boston Edison Company Application For Approval For Onsite Disposal Of Slightly Contaminated Soil -- Attachment II i
! REFERENCES d
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. e ? i j REFERENCES [1] NUREG 1101, "0nsite Disposal of Radioactive Waste" l [2] Licensee Event Report 82-19/03L l [3] Licensee Event Report 77-29/IP t i [4] Licensee Event Report 88-026 j i [5] NRC Inspection Report 50-293/81-04 j [6] U.S. Nuclear Regulatory Commission Regulatory Guide 1.109,
" Calculation of Annual Doses to Man From Routine Releases of
- Reactor Effluents For The Purpose Of Evaluating Compliance With j 10CFR50, Appendix 1."
a [7] U.S. Nuclear Regulatory Commission NUREG/CR-3332, Radioloaical Assessment, 1983.
- [8] Kocher, D.C. and Sjoreen, A.L., 1985, " Dose-Rate Conversion Factors For External Exposure To Photon Emitters In Soil," Health l
Physics, 48, 193 (attached), i i i 4 i f i i 4 4 ) L 1 ( ) 1 f
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O Boston Edison Company-Reference 8 Kocher, D.C. and Sjoreen, A.L., 1985,_
" Dose-Rate Conversion Factors For External Exposure To Photon Emitters In Soil "
Health Physics, 48, 193 0 O .
i j 3 i px;gg v '~- ~ < - qWu l O i I i DOSE-RATE CONVERSION FACTORS FOR EXTERNAL EXPOSURE TO PHOTON EMITTERS IN SOILt D r.KOCllER Health and Safety Researth Dnision. Oak Ridge National 1.aboratory, Oak Ridge. TN WO
, and
, I l ' A. L. MOREEN I Computer Sciences. Union Carbide Corporation Nuclear Daision. Oak RtJge. TN 3730 Met enrd 20 /ul.r 1983; accepted 14 hmicer 1984) 8 Abstract-Dose-rate conversion factors base been calculated for external esposure abose ! I ground to monoenergetic photon emitters in soil. These factors give external dose rates per j unit source concentration m soil. The calculations are based on the point-Lernel integration 4 method and assume that the source concentration at any depth in soil is uniform oser an l in6 nite surface parallel to the ground plane. Doseeate factors in air at a height of 1 m abose l ground are tabulated fot dncrete photon energies nween 0.01 and to MeV and for source l depths in soil between 0 and 300 cm. Application of the results for plane sources in soil to i j l the calculation of photon dose rates from distnbutions of sources with depth in soil is desenbed, and dose-rate factors are tabulated for the particular cases of uniform slab sources of finite thickness and sources which are exponentially distnbuted with depth. We aho demonstrate how dose-rate factors in air for monoenergetic photon sources are used to estimate dose. rate factors for body organs of exposed indmduals and for the spectrum of O photons from radioactne decay. The calculations in this paper show that allowing for downward migration of radionuclides in soil can result in significant reductions in external dose compared with the usual assumption that radionuclides which are deposited on the ground surface remain there until removal by radioactise decay. INTRODt'CTION for example, currently uses this approach in ENTERNAL dose from radionuclides deposited estimating external doses from routine releases on the ground often has been estima.a by of radioactivity from nuclear power reactors assuming that the activity remains on the gro .nd (USNRC77). For radionuclides deposited on surface until removal by radioactive decay. soils. this assumption leads to overestimates of The U.S. Nuclear Regulatory Commission, external dose to exposed indisidual3 abose ground, because the activity normally will be transported into the soil, e.g. by water infiltration t Research spcasored by the Orhce of Radiation and by plowing of agricultural lands, and the Programs, U.S. Ensironmental Protection Agency resulting layer of soil between the source and under Interagency Agreement AD-89.F-2A-279 with receptor locations will provide greater shielding the U.S. Department of Energy under contract W. than the air above ground alone. 7405-eng-26 with the Union Carbide Corp. Although hiodels and data bases for estimating distri-the research descobed in this report has been funded by the U.S. Ensironmental Protection Agency. it has butions of radioactivity in soil and their asso-not been subjected to the Agency's required peer and ciated external doses above ground have been policy review and therefore does not necessanly presented in the literature (Be68a; NRPB79; reflect the views of the Agency and no official en- Be80). However, these methods are not yet used dorsement should be inferred. routinely in environmental dose assessments. 193 O . i i
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l M.1
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1 19-1 doser VII C Ou i RSION F ACTORS i i l 1his paper presents ca! u!ations of esternal Joses from espesure to particular radionuclides l l dose-rate conscrston factors in air abase ground whica are of interest in environmental dose 6 i for photon sources in soil for use in ensiron- 1ssessments. i mental d0se assessments. The dorrate comer. ~ht importance of accounting for shielding l sion factor, which we also call the dose rate M he radiations by soil as photon sources factor is Jefined as the dose rare per unit source o,, grate below the ground surface can be dem-mncentranon in soil The calculations in thn onstrated by considenng e sternal exposures paper represent an estension of previous results dunng constant chronic releases of raJionuclides for photon sources which are confined to the to the atmosphere. Far radionuclides with half-ground surface (Koso. Kosla: Ko83a; KoS3bt hses of more than a few hours and a deposition The source concentration at any depth in soil selocity of about 1 em/s. the predicted photon , is assumed to be uniform oser an infinite surface dose rate from actisity deposited on an impen-parallel to the ground plane. etrable ground surface esceeds the dose rate The dose-rate factor is apphed to environ- from immersion in the atmosphene cloud within mental dose assessments b> means of the general a few hours of the onset of the esposures equation (Ko83bt Furthermore, for long-lised radionu-clides. the predicted dose rate from the activity
/I(t) = x(n DRF. (1) deposited on an impenetrable ground surface dunng a long-term chronic release to the :t-where // is the esternal dose raie at time I, x is mosphere eventually exceeds the dose rate from the source concentration at the location of the air immersion by several orders of magnitude.
exposed individual, and DRF is the dose rate Further indication of the need for more re-factor. The concept of the external dose rate alistic edeulations of external dose from radio-
, factor is discussed in more detail elsewhere nuclide;, deposited on the ground is provided
.; (Ko80; KoSIa; Ko83a; Ko83b). We emphasize by a recent analysis of health nsks from geologic here that the dose-rate factor for photon emitters disposal of high level wastes (SmS2a; Sm82b).
1 on the ground surface depends on the height of In this analysis, a significant contnbutor to the the receptor location abose ground; this height predicted radiological impacts from repositories is usually assumed to be I m. For photon in basalt or shale is external exposure to long-emitters in soil; howeser, the dose-rate factor lived '"Sn which is deposited on the ground depends on the depth of the sources in soil but surface via irrigation of contaminated river usually is insensitive to the height of the receptor water, location above-ground for heights of about 10 External dose from electron emitters which m or less (Be68at are distnbuted in soil is not considered in this i in this paper, dose-rate factors in air above- paper. The range in soil for electrons from l ground for plane sources in soil are calculated radioactive decay is usually less than 2 cm and for discrete photon energies between 0.01 and never exceeds 4 cm (NAS64L Therefore, a I 10 MeV and for source depths in soil between nominal penetration of radionuclides into soil 0 and 300 cm. These results are then applied will provide complete shieldit:g from all electron to the more realistic problem of estimating radiations. External dose-rate factors for electron
- external dose rates from distributions of sources sources which are assumed to be confined to {
with depth in soil, and dose-rate factors are the ground surface are given in recent reports ' calculated for the particular cases of sources (Ko81b; Ko83a), j which are uniformly distributed in a slab of finite thickness and sources which are exponen- DO5E-RATE FACTORS FOR PLANE tially distributed with depth. We also demor- sot;RCES IN SOIL strate how the dose-rate factors in air for mon- This section presents calculations of photon oenergetic sources may be used to obtain dose- dose-rate factors in air above ground for mon-rate factors for different body organs of an oenergetic sources as a function of emitted exposed individual and for the spectrum of energy and depth of the sources in soil. The ' ! photons from radioactive decay; it is organ calculations are based on the point-kernel inte- l l 1 i l i
a f (3_) D C. KOCHER and A L. SJOlEEN 195
.tionuclides gration method and assume that the source between the source and receptor locations ental dose concentration is uniform oser an inhnite surface ( Be68a).
parallel to the ground plane. In pnnt pie the calculation of dose-rate fac-r shieldmg In previous papers (Ko80; Ko81a: Ko83a: tors above ground for photon sources in soil is m sources KoS3bt the dose-rate factor in air abose ground more complicated than for sources which are
;n be dem-for monoenergetic photon sources which are confined t i the ground surface. because the exposures con 6ned to the ground surface was obtained by radiations ' ass through 2 ditTerent media be-t.ionuchdes integrating the photon specific-absorbed fraction tween the ;ource and receptor locations. In ; with half-
{ (Ec6Sb) in air at the receptor location over an practice, however. the calculation can be sim-deposition , infmite ground plane. The result is plified by recognizing that the shielding provided
- ed photon i by a given thickness of material is proportional an impen- '
to its density. For a receptor location which is dose rate DRF,9 c, E,) = (1/2)KE,(u, /p).,j(fdu,:) 100 cm abose ground, the shielding provided oud within by air is thus equivalent to the shielding provided exp s tres C," i D,, - 1) exp[(Da - 1)u;]} . (2) by only about 0.1becm of soil. for and photon , J radionu-transport in air can neglected nominal he activity depths of the sources below the ground surface. , ad surface ! tere, DRF " is the photon h) dose-rate factor Therefore, by analogy with eqn (2). it is a good
- m the at- in air W in units of Gy/a per Bq/cm';
- is the approximation to calculate the dose-rate factor 4 ' q from height sf the receptor location above ground in in air abose ground as a function of depth x of agt ude. cm; E, is the photon energy in MeV; K is a the sources in soil (s) according to the equation a
? mae re- constant equal to the product of 1.6 x 10'"' g-g m radio- Gy/MeV and 3.15 x 10' s/a; (u,,,/p)a and g,, f t . provided are the mass energy absorption and linear atten- DRF,"(x, E,) = (l/2)KE,(u,,,/p)aj$due )
n geologic , . ion coctlicients in air for energy E, in units S of cme and em", respectively; C and D are - C' "U%p). ac the coemeients in the Berger form of the energy- (D - 1) exp((D. - 1)u,x]} . (5) 4
'positones absorption buildup factor in air, B,,,", for energy e to long' E, gisen by (Tr66) Calculated dose-rate factors in air for discrete te g ound photon energies betwten 0.01 and 10 MeV and tied river B,,,"(u,r) = 1 + C,uar exp(Deuor), (3) depths of the sources in soil between 0 and 300 cm are given in Table 1. The values for zero where r is the distance from any point in the depth represent the usual assumption of souw d which are confined to the ground surface at:0 f""fom ns r source region to the receptor location; and fi is the first-order exponential integral are calculated from eqn (2) for a height : = 100 cm and cm The values for nonzero depths m soil are erefore, a calculated from eqn (5), and they apply to any
;into soil
,,I gg) , e.tp( oridr. (4) height within a few meters of the ground surface.
11 electron u r Dose-rate factors are listed only if they are ir electron within about 10 orders of magnitude of the mfined to For an em cd individual standing on the "alue for sources which are confmed to the nt reports . ground the dose-rate faar is usually calculated ground surface. txcept when additional values i for the single height a 400 cm above ground. would facilitay nurr.encal interpolation. The 2 terms in eqn g2) involvinc the expo- I ne mast eacrgy-absorption and linear atten-NE nential integral and the buildup factor give the uation coefficients in air used 6. the calculations contributions from unscattered and scattered for Table I were obtened from the en npilation
>f photon photons, respectively. Similar considerations of Hubbell (Hu6m. The buildup factor coetb for mon- apply to eqns (5) and (8) below Cht relative cients in nir, C, and D., were obtained from a , f emitted importance of the contributiont . o .i scattered linear le,at-squares fit of eqn (3) to published soil. The and unscattered photons depends on the photon energy-absorption buildup factors (Ch68; C169).
- rnel inte- energy and the areal density of the medium Linear attenuation coefficients and energy-ab-O O
p A
- .7.
. ig ;. -
J
. .up e _. ..
I l ( l , l l l ! l [ y 5 l li!I)lC I. l)JWrdle Outver\ tort fsk fors (Gyfa f 44 th}lCnOI Ut Utr slivre getritthl h 4 ]>]atic wmt o at sfilicwn! sls o
- tis \ In wtf
~~
l - . , - - _ _ _ _ . _ _ .._ i [ Emitted photos enes8y (MsV) j Depth 0.030 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.100 i l (col 0.150 0.200 0.300 0.400 C ; 0.0 5.54R-05 6.6 4E-0 5 5.68E-05 4.13E-05 3.56E-05 3.48E-05 3.62E-05 4.18E-05 5.12E-05 7.0$E-05 f. 0.5 5.81F-14 2.95E-08 8.06E-07 4.25E-06 6.22E-06 7.50E-06 9.12E-06 1.36E-05 9.3CE-05 1.s7F 04 1.79F 04 1.0 2.57E-22 2.011'-05 3.61E-05 5.15E-05 2.0 5.94E-11 1.04E-38 4.17E-16 4.30E-08 1.31E- 1.08E-06 4.53E-06 6.11E-06 1.00E-05 1. 51E- 0 5 2.87E-05 4.11E-05 8.58E-05 6.96E-05 1.16E-04 9.42E 05
?[
- 1. 9 8 E - 10 3. 80 E- 01 1.02E-06 2.11E-06 3. 3 8E- 06 6.45E-06 m 3.0 1.12E-12 2.93E-03 3.86E-07 1.10E-06 2.0$E-06 4.47F-oe 1.06E-05 2.09E-05 3.01E-05 5.25E-05 7.161-05 g 4.0 7.80E-06 1.62E-05 2.35E-05 4.22E 05 5.0 6.85E-15 5.09E-09 1.55E-07 6.00E-07 1.29E-06 3M9E-06 5.87E-06 1.28E-35 1.8eE-05 3.47F 05 4.80E-05 4.82E-05 d
- 9. 'i 6 E- 10 6.37E 08 3.35E-07 8.33E-07 2.321506 4.49E-06 Z 7.5 1.37E-11 7.42E-09 8.27i!-08 2.90E-07 1.08E 06 2.37E-06 1.03f-05 1.52E-05 2.90E-05 4.07F 05 <
10.0 2.16E-13 9.06E-10 6.IIE-06 9.26E-06 1.92E-05 2.76E-05 15.0 5.81E-17 1.43E-11 2.13E-08 1.0$E-07 5.17E-07 1.28E-06 3.72k-06 5.17E-06 1.30E-05 1.93E-05 h m i 1.48E-C' 1.42E'08 1.22E-07 3.85E-07 1.42F-06 20.0 2.36E-13 1.06E-10 2.31E-06 6.13E-06 9.72E-06 6 25.0 1.97E-09 2.96E-08 1.18E-07 5.50E-07 9.44E-07 2.96E-06 3.91E-15 1.66E-12 2.77E-10 7.23E-69 5.02E-06 Z 30.0 6.64E-17 5.60E-13 3.9M-11 1.77E-09 3.65E-08 2.15E-07 1.13F-08 8.45E-08 3.89E-07 t.44E-06 2.62E-06 m 40.0 1.61E 07 7.09E-07 1.3hE-06
- 50.0 3.03E-15 7.93E-13 1.08E-10 1.10E-09 1.315-08 1.62E-14 6.57E-12 1.osE-10 2soeE-09 2.? 9E -0 8 1.7)E-07 3.851-07 ]
60.0 4.85E-09 3.31E-16 4.02E-13 1.06F 11 3.23E-10 8.47E-10 4 . 2 3 E- 0 8 1.09E-07 y 80.0 1.ueE-06 3.08 -08 ;g 1.52E-15 1.02E-13 7.99E-12 2.60E-11 100.0 9.9)E-16 6.35E-10 2.49E-09 VC 120.0 1.99E-13 7.9BE-13 3.89E-11 2.02k-10 140.0 4.94E-15 2.46E-14 2.39E-12 1.45F 11 160.0 7.59E-16 1.47E-13 1.34E-12 180.0 9.02F-15 1.10 E- ! J 8.961-15 L
% d air y - N-- wee a r - - - - - - - - -
}
N U L I l Tis!ric l . (s oort: mated)
~
l t Emitted photon e**F87 IM*%1 Depth 0.500 0.600 0.800 1.000 1.500 2.000 3.000 5.000 4.000 6.000 8.000 10.000 (se) 9 0.0 2.19E- 0 4 2.57E 04 3.2 9E-0 4 3. 92 E-04 5.32E-04 6. 51 E- 0 4 8.e4E-04 1.06E 03 0.5 1.44E-04 1.70E-04 2.19E-04 2.6 2 E- 0 4 3.97E-04 4.42E-04 5. 8 8 E-0 4 7.18E-04 1.2 5 E- 01 1.42 E 03 1. 7 7 t> 0 3 2.14E-03 p 8.4 2 E- 04 9.5 8 E -0 4 1.101: 01 1.421-03 1.0 1.17 E-0 4 1.38E-94 1.78E-04 2.13 E-04 2.91E-04 3.61E-04 4.8 2 E-0 4 5.90 E- 0 4 6.92E-b4 7. 8 9 E- 0 4 9.7 9E 04 8.91E-05 1.06 E-0 4 1.17 E 03 2.0 1. 3 7 k -0 4 1.64E-04 2.25E-c4 2.80E,04 3. 77 E- 0 4 4.6 3 E-0 4 5. 4 5 E- 0 4 6.22E-04 7.73E 04 9.22F-C4 h,9 3.0 7. 2 5 E-0 5 8.64E-05 1.12E-04 1.35E-04 1. 8 7 E-0 4 2.34E-04 3.17E-04 3. 91 E- 0 4 4.6CE-04 5.27E-04 6.55E 04 4.0 6.07E-05 7.27E-05 9.50E-05 1.15E-04 7.51E 04 1
- 1. 6 0 E- 04 2.02E-04 2 . 7 5 E-0 4 3. 40E -04 4.02E-04 4.60E-04 5.73E-04 6.84E-04 07 5.0 5.16E-05 6. 21 E- 0 5 8.18 E- 0 5 9. 9 5 E- 0 5 1.40E-04 1.77E-04 2. 4 3 E-0 4 3.02E-04 3.57E 04 4.10E-04
- 7.5 3.57E-05 5.11 E-0 4 6 .10 t - 0 4
- 4. 3 6 E-0 5 5.8 7 E-05 7.24E-)$ 1.0 4 E- 0 4 1.34E-04 1.87E-04 2.35E-C4 2.196-04 3.22 E 04 10.0 2.54E-05 3.15E-05 4.34E-05 5.45E-05 8. 0 $ E- 0; 1.05E-04 1.50E-04 1. 90 E 0 4 2.176-04 1.62E 04 4.03 E -0 4 4.81E 04 y 15 0 1.34E-05 1.72E-05 2.4 9E- 0 5 3.24E-05 1.30E 04 3.SSF 04 C1 5.07E-05 6.86E-C5 1.01E-04 1.32E-04 1.59E-04 1.86E-04 2.35E 04 2.83E-04 j 20.0 7. 26 E-06 9.64E-06 1.47E-05 1.99E-05 3.31E-05 4. 6 5 E-0 5 7.18E 0 5 9.53E-05 1.17 E -0 4 1.37E-04 25.0 3.98E-06 5.4 8 E-06 1.76E-04 2 .12 E - r:4 '
- 8. 8 3 E-06 2.20 E-06 1.24E-05 2 . 21 E-0 5 3.23E-05 5.2DE-05 7.07E 05 8.77E 05 1.040 04 1.35E 04 1.6 3 E 04 I 30.0 3.14E-06 5.35E-06 7.8 4 E-06 1.4 9E -0 5 2.27 E-0 5 3 . 81 E-0 5 5.33E-05 6.71E-05 8.07 E- 0 5 1.05' 04 1.2tF-04 40.0 6.77E-07 1.05E-06 2.00E-06 3.18E-06 6.93E-06 1.15E-05 2.13 E-0 5 3.12E-05 4.0 5 E-0 5 cf.
50.0 2.11E-07 3.52E-07 4.97 E- 0 5 6.65E-05 8.19E- 0 5 5
- 7. 5 6 E-07 1.31E-06 3.28E-06 5.91E-06 1.21 E-0 5 1.8 8 E-0 5 2.11E-01 3.15E 05 5.3 8F 0 5 60.0 6.61E-08 1.39F-07 2.88E-07 5. 4 3 E-0 7 1.57E-06 3.0 9E -06 6. 9 9 E--06 1.14E-05 1.58E-05 2.03E-05
- 4. 3 2 E- 0 5 2.86E-05 N
80.0 6.5 4 E '09 1.38E-08 4.22E-08 9.47E-08 3 . 6 6 E-07 3.61 F - 0 5 m
- 8. 5 8 E-07 2. 3 9E-06 4.37E-06 6.50E 06 8.74E-06 1.30E 05 1.6 9E- 0 5 P 100.0 6.51E-10 1. 61 E- 0 9 6 .2 4 E-0 9 1.67E-08 8. 6 3 E- 0 8 2. 4 2 E-07 8.31 E- 07 1.71E-06 2.720 06 !
3.86 E- 06 6.07 E- 06 8.14E 06 120.0 6.50E-11 1.89E-10 9,28E-10 2. 95 E-09 1.0 $ E- 0 8 6. 90 E-0 8 2. 92 E-07 6.78F-07 1.17E-06 1.73E-06 2.8 9 E- 06 3.00E 06 140.0 6.51E-12 2. 21 E- 11 1.38E-10 5.2 5 E -10 4. 90 E- 0 9 1.98E-08 1. 0 4 E- 07 2.71 E- 0 7 5.0 3 E- 07 7.8 5 E- 07 1.39E-06 1.99E 06 160.0 6.52E-13 2.60E-12 2.06E-11 9.345-11 1.17 E-0 9 5.6 8 E-0 9 3.6 9E- 08 1. 0 9 E- 0 7 2.18E-07 3.58E-07 6.7e E- 0 7 1.00 E- 06 180.0 6.54E-14 3.05E-13 3.08E-12 1.67E-11 2.82E-10 1.6 4 E- 0 9 1. 3 2 E-0 8 4.3 9E-08 9.51E 08 1.64E-07 200.0 6 . 56 E- 15 3.59E-14 4.61E-13 2.97E-12 6.77 E-11 3.31E-07 5.osE-07 4.73E-10 4. 7 3 E-0 9 1.78E-48 4.16 E- 08 7.57E 01 1.62E-07 2.596 07 250.0 1.71E-16 4.00 E- 15 4.01E-14 1.92E-12 2.13E-11 3.66 E- 10 1.87E-09 5. 3 2 E-0 9 1.10E-04 2.79E-08 4.87t-08 300.0 5. 4 3 E- 16 5.50E-14 9.64F-13 2.85k-11 4.98E-10 6.88E-10 1.6 3 k 0 9 4.8 4 t-0 9 9.3cE 09 1
~
.,- . ,u-
~ .
1 J le DUSI .R M E CON \ E RMON FACIORS 4 wrption buildup fa; tors for soil hase not been then we must take into account the shielding
- pubhshed. These parameters were obtained by prosided b.s air between the ground surface and 1 assuming that as ailable data for concrete (Ei75) the receptor location. In this case,4 ts not zero are a reasonable approximatton. The linear ar- hut is equal to the depth of so:1 which prosiJes tenuation coe:ficients m soi! were obtaineJ from the same shielding as the air abme ground. As J
a the mass :ntenuation coeficients in concrete by we discussed in densing eqn (5). x: is approx. ' equal to iW ':. w here : is the beight of the assuming a soil density of I.a g,em) j The results in Table ! show that only about receptor location abose ground. The factoc 10" { l em c' soil prosides essentially complete inciudes the ratios of the densities of atr and j shielding for the : lowest photon energies. On soil and the mass attenuation coetticients m air the other hand. more than IOC em of soil is and soil. The latter ratio depends on the photon j reqmred to reduce the dose-rate factors for energy, but is near unity in most cases (Hu69, photon energies abose 1 MeV by about 4 orders Ei75). of magnitude or more compared with the dose- For arbitrary distributions of sources in soil, rate factors for sources on the ground surface. eqn (6) must t,e sched by numencal integration. The dose rate factor as a function of photon DONE-R slE F ACIOR5 FOR DISIRIBt'TIOM OF energy and source depth in soil in the integrand , sot:RCE.5 M ill! Dil'Hf IN 5011. can be obtained by interpolation of the salues Radionuclides in soil normally will be distrib- in Table 1. uted continuously with depth rather than con-i tined to a plane surface at a single depth. In c erm smm' dmdse this section, we consider the calculation of j ds an application of egns (5) and (6), we external dose rate factors for arbitrary distribu- consider sources which are uniformiv distnbuted tions of sources with depth in soil and for the w thin a slab of finite thickness. Such an ap-I g particular cases of uniform slab sources of finite proximation may be appropriate. for examole. 4 thickness and sources which are exponentially for contaminated soils which are freque Jv i distnbuted with depth. plowed or for use with linear compartment ! models of radionuclide transport in soilin which clrburary warce distributwns the soil is assumed to be divided into a senes it we assume as in obtaining eqn (5) that the of well-mixed lasers. Since the source concen-source concentration at any depth in soil is tration in eqn (6) is uniform in this case, the uniform over an infinite surface parallel to the dose-rate factor can be obtained by integrating ground plane, then from eqn (1) the dose rate the plane-source dose-rate factor in eqn (5) ovei in air above ground foi a moncer metic source the sertical extent of the slab. From the relation which is distnbuted with depth in soil can be for derivatives of exponential integrals (Ga65) I obtained by integrating the product s . the dose- g sen bs rate factor and source conce.ntration over the - vertical extent of the source region. The dose . . ! rate in air #/, for energy E, is thus given by dE.,(w)/de = -E,y(w), (7) Of(xi, x , E,, t) the result is a
= x:(x, t)DRF,"(x, E,)dt, (6) DRF,"(xi, x2, E,) = (1/2)KE,(pm/p), I n y, where xi and x: are the upper and lower bound- C anes of the source region, respectively, and x,(x, x (f f;( ,ri) - $ (g,r ) ( + D, - 1)* ,
t) is the source concentration at depth x and . - time t in Bq/cm' X exp((D, - 1)u,xi} - expi(D, - 1)urt ] , l If the upper boundary of the source region, . . l x,, in eqn (6) corresponds to the ground surface, (8)
.M k
w p D C. KUClil an , L.MORLIN IW
/
sh'idmg where the dese-raty fa: tar is in units of Gy/a JNuss in the next section. the same reduction unate and per Bq/cm) and E: is the second-order mpo- in dose rate would apply to all body organs of M not zero nential integral gisen by (Ga65) an exposed indisidual standmg on the ground. h proudes . , The results in Tables ! and 2 also show, howewr,
- round As E:M " exp! m i u EM. (9) that it may not be reasonable to neglect the n approx. additionai dose that would accrue as high-enerp
;ht of tim Dose-rate factors ior a .'niform slab source photon emitters migrate beicw the 15-em pl owed ' actor 10' with upper boundan at the ground surface and lay er.
af air and depths of the lower boundary between 0.5 and . As a second example, consider a hncar com-ents in air ISO em are gnen in Table 2. The calculatiers partment model which has been developed to he photon take into account the thickness of air between desenbe the downward migration of radiocu- .es (Hu69; the ground surface and the receptor location as clides in undisturbed soil (NRPB79). Exposure desenbed following ean (6). A blank entrv in- to sources in undisturbed soil probably is more
'es in soil. dicates that the last value entered in that column common than exposure to sources in plowed iteration. is reneatei_for a_llyreater depths of the lower soil. In this model, the nrst 30 cm of soil is
)f photon boundary The last va!ue for each energy tEs divided into 4 compartments of depths 0-1 cm, integrand gives the dose rate factor for a uniform, semi- 1-5 cm, 5-15 cm, and 15-30 cm. A similar the values inlinite source region. I he reduction in the model (SjS4) includes an additional compart-additional contnbution to the dose-rate factor ment between 30 and 100 cm. The downward with increasing depth of the lower boundary is migration ef activity is described by transfer
; apparent from the dependence on depth of the coetheients between adjacent compartments, and d M we , dose-rate factors for plane sources given in within each compartment the radionuclide con-
!istnbuted i Table 1. For energies between 0.2 and 3 Ntev, centration at any time is assumed to be uniform. 'h an up- the last entries in Table 2 are about 15c'c greater The dose rate tattor for sources of any energy eumpl, than the dose-rate factors for uniform sources in the nrst compartment can be obtained by 'requently previ usly c lculated by Beck and de Planque interpolation of ti.e values for 1-cm depth of pa O t uaing a polynomial expansion matnx equation the lower boundary in Table 2. For the other inL h method (Be68a), compartments, however, the upper boundary of ) a seYes Use f the results in Table :in environmental the source region does not correspond to the concen- dose assessments is illustrated as follows. Radio- ground surface. In this case, v.2 use the fact case, the nuclides deposited on agneultural soi!s are often that the dose-rate factor for a uniform slab itegrating assumed to be uniformly mixed in the nrst 15 source in eqn (8) obeys the general superposition 1 (5) oser em of soil as a result of frequent plowing relation . relation
, (USNRC77). Consider, for example, the dose DRF/('(' x:)
s (Ga65) r te in air at a height of I m abose ground fo* a source of 1-MeV photons of concentration 0.1 Bq/cm which is uniformly mixed in the 3 = DRF/(x,, x:) - DRF/(xi, x'), (10) plowed layer. From the dose-rate factor for 1 where xi < x' < x2 and the dependence of the A MeV and 15cm depth in Table 2, the dose rate dose-rate factor on photon energy has been is 10.1 Bq/cm )(1.4 X 10'3 Gy/a per Bq/cm 3) suppressed. Thus, the dose-rate factors for the 3
' l.4 X 10-* Gy/a. !f the entire quantity of uniformly mixed compartments below the activity were assumed to be confmed to the ground surface can be obtained by simple sub-t ~
ground surface instead of uniformly dispersed tractions of values obtained from Table 2. For [ ' in the plowed layer, then the surface concentra- example, the dose rate factor for sources of 1-tion would be 1.5 Bq/cm and. from the dose- MeV photons in the 5-15 cm soil byer is the 3 rate factor for 1 MeV and zero depth in Table difference between the values for 0-15 cm and l : 2 1, the dose rate would be (1.5 Bq/cm )(3.9 0-5 cm slab sources, or (1.4-0.8) X 10- 3 e 0.6 x 10-4 Gy/a per Bq/cm 2
) = 5.9 x 10-' Gy/a. x 10'3 Gy/a per Bq/cm . The dose rate in air 3
.,I g3j' Therefore, uniform mixiog of the activity in 15 from the calculated activity in each comt. art-
cm of soil reduces the dose late by about a ment is then obtained usirg egn (l), as illust:ated i< (g) factor of 4 for this photon energy. As we shall in the first example given above. l(I
!*1
!ei
!9l m, {l
( ! + Li k f~ #\
- - - . _ - - - _ . . ..-..o..
u_, 0
.1 l
Table 2. Daw-rate conversion factors (Gy/a per lkt lem'y in air abme growid Isr umiburn slab wim a between the grotmd swla c ami Jdlerent depths in wJ faitted photon eser8y (hsV) m Depth 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.100 0.150 0.200 0.300 0.400 50 (se) , m 0.5 1.4 6 E- 0 8 5. 5 2 E-07 1.7 9E-06 3.42E-06 3.83E-06 4.13 E-06 4.7 3 E-06 6.6 5 E- 06 9. 6 0 E- 06 1.68E-05 2.40E-05 3.97E-05 5.3 7 E-0 5 h 1.0 5.54E-07 1. 92 E-06 4.6 4 E- 06 6.03 E-06 7.0 4 E- 06 3.44E-06 1.25E-05 1. 8 4 E- 0 5 3.2 s E-G S 4.6 9E-0 5 7.8tE 05 2 .co E- 0 4 Z 2.0 1. 93 E- 04 5.2 0 E - 06 7. 8 7 E- 0 6 1. 0 2 E-0 5 1. 3 0 E- 0 5 2.0 5 E-0 5 3.12 E-0 5 5.72E-05 8.19E 05 1,3 8 E- 04 1.87F 04 < 3.0 5.2 s E-06 8. 51 E-06 1.17 E-0 5 ' t . 56 E-0 5 2.59E-05 4.03E 05 7.56 E- 0 5 1.08E-04 1. 8 5 E- 0 4 2. 5 2 E- 0 4 ] 4.0 5.2 9 E-06 8,77 E- 06 1.25E-05 1.73E-05 2. 94 E-0 5 4.71E-05 9.00E-05 1.2 9E-0 4 2.24E 04 3.05E-04 un 5.0 8. 8 7 E-46 1. 3 0 E-0 5 1. 8 3 E-0 5 3.24E'05 5.22 E- 0 5 1.0lE-04 1. 4 6 E 0 4 2.53E-04 3. 4 9E- 0 4 { 7.5 8.93E-06 1.34E-05 1.96 E-0 5 3.64E-05 6.05E-05 1. 21 E- 0 4 1.76E-04 J.15E-04 4.3 3 E-0 4 gt 10.0 8.94F-06 1.353-05 2.01E-05 J.83E-05 6.4 9E-0 5 1.34E-04 1.95E 04 3.54E 04 4.9tE 04 , 15.0 1.36E-05 2.03E-05 3.97E-05 6.8 6 E- 0 5 1. 4 5 E-04 2.14E 04 4.our 04 5.61004 y' 20.0 4 .00 E- 0 5 6.97E et5 1. 5 0 E- 0 4 2.21F-04 4.2tE 04 5. 96 E-0 4 q 2.24E-04 4.32E-04 6.15E-04 4.01 E-0 5 7.01 E-0 5 1.52 E -0 4 l 25.0 7.02E 05 1.52 E 04 2. 2 6 E- 0 4 4.37E 04 6.24E-04
]
y
! 30.0 ! 40.0 1. 5 3 E -04 2.26E 04 4.4?E 04 6.32E-04 m 50.0 2.27E-04 4.42E-04 6.34E-04 60.0 e.35E-04 l
L r. e _ 9 _ . _ __ _y 9
rm
? >
)
\d) i \
) \ i
\
(/ (/ k TaNe 2. (wntinued) Imitted photue emergy (MeV) i Depth 0.500 0.600 0.80C 1.000 1.500 g 2.000 3.000 4.000 5.000 6.000 8 000 10.000 , (cm)
- _ - - - - - . r 0.5 6.66 E-0 5 7.89E-05 1. 0 2 E-0 4 1. 2 2 E- 0 4 1.66E-04 2.0 $ E-0 4 2.72E 04 3.321r04 3.89E-04 4. 4 2 E- 0 4 5.48E-04 6.5 3 E-0 4 7 3.0 1.3 t E-04 2.00E-04 2.3 9E- 04 3.26E-04 4.03E-?4 5. 3 6 E -0 4 6.55E 04 7.68E 04 2.0 2.32E-04
- 1. 5 5 E- 0 4 2.75E 04 3.55k-04 15E 04 5.80E-04 7.19E 04 9.59E-04 1.17 E- 0 3 1. 3 e E- 0 3
- 8. 7 4 E-0 4 1.57E"03 1.08E'03
- 1. 95 E- 0 3 1.2 9E- 03 2.321 03 ka 3.0 3.13E-04 3.71E-04 4.7 9E-0 4
- 13E-04 7.85E-04 9.74E 04 1. 3 0 E-0 3 1. 6 0 E --0 3 1. 8 8 E 0 3 2.14E-03 2.66E 03 3.17t-03 F 4.0 3. 7 4 E-0 4 4 . 50 E-0 4 5.8 2 E-0, 6.94E-C4 9.58E-04 1.19E-- 03 1.60E 03 1.9e E03 2.31E 0 3 2.63E 03 3.2 7 E- 03 3.90E 03 7' 5.0 4.35E-04 5.17E-04 6.70E-04 8.35E-04 1. I l E-01 1.38E-03 1.86E-03 2.2 8E- 03 2. 6 9E-03 3.07E 03 3.4t E- 03 4.54F 03 c 7.5 ).43E-04 6.47E-04 8. 4 3 E- 0 4 1.02E-03 1.4tE-03 1.77E-03 2.3 9E-03 2.95E-01 3.4 7 E-03 3. 9'J t-0 3 4.94E-03 5.90E-03 10.0 4.18E-04 7. 40 E -0 4 9. 7 0 E- 0 4 1.17E 03 1.64E-03 2.06 E-03 2.8 t E-03 3.48E-03 4.10E-03 4.70E-r3
[ 5.BSE 03 6.98E-03 - 15.0 7.12E-04 8. 5 8 E -0 4 1.14F 03 1.39E-01 f . 96 E- 03 2. 4 9 E--03 3.4 2 E- 03 4.27E 03 5.0$E-03 5.801-03 7.24E 03 8.6 5 E- 03 20.0 7.62E-04 9.2 3 E- 04 1.23E-03 1.51F-03 2 .16 E - 0 3 2. 7 7 E-03 3.85E-03 4.83E 03 5.73E 03 6.60E 03 8.26 E 03 9.6 8 E- 0 3 r-25.0 7.89E-04 9.60 E- 04 1.29E-03 1. 5 9F - 0 3 2.30E 03 2.97E-03 4.16 E-0 3 5.24E-03 6. 24E- 03 7.20E 03 9.03E-03 1.08E-02 30.0 8.04E-04 9.81E-04 1. 3 2 E --03 I.64E-03 2.3vE 03 3 .10 E- 03 4.38E 03 5.55E-03 6.6 2 E43 7.66E 03 9.6 3 E -0 3 1.15E 02 $ 40.0 8.17E-04 1.00 E- 0 3 1.36L-01 1.5 9E 0 3 2.50E-03 3.27E 03 4.67E-03 5.96E-03 7.ISE-03 5.30E 03 1.051-02 1.26 E U2 O 50.0 8.2sk-04 1.OIE-03 1. 3 7 E- 0 3 1. 7 2 E- 0 3 2.54E 01 4.8 3 E- 03 60.0 8. 2 3 E-04 1.3bE P3 1.72E-03 2.57E 03 3.35E-03 3.3 9E~03 4.93 E-0 3 6.20E 03 6.35E-03 7.47E 03
- 7. 6 7 E-0 3 8.70E 03 8.95E 03 1.10E 02 1.14E 02 2.32F-02 h m
.31E 02 BC .0 1.731' 03 2.5aE 03 3. 4) E- 03 5.01E-03 6. 50 E- 0 3 7.88E 03 9.2 3 E- 0 3 1.16E 02 J .4 2 E -02 2 100.0 2.19E- 03 3.44 E -03 5.04E-03 6.35E-03 7.97E 03 9.34E 03 1.19E 02
- 44E-02 .
120.0 5.05E 03 6.57t-03 8.00D 03 9.40E 03 1.20E-02 1.45F-02 140.0 6. 5 8 E- 03 8.02E 03 9.421-03 1.21E 02 1.46E 02 160.0 6.59E-03 9.43 E 03 180.0 9.4 4 E 03 tJ Q. 9-9 _ ___. O_J
-~
N S fa Ta!>!< 3. Darw-rate aniwrsion fas surs ((iy/a jvr lhllcm') in air ri.< se n:wini./ is er njuoms,irial!r alistrilriacal wous n iri wil a Psitted photos emergy (WeV) e 0.010 0.015 0.020 0.030 0.040 0.050 0.060 0.080 0.190 $.150 (1/cm)* 0.200 0.300 0.400 0.01 1.97E-27 8,24E-15 9.04E-11 1.32E-08 5,00E-Og 9.41E-08 1.52E-07 3.17 t - 07 5.6BF 07 1.27E ^6 1.8#h 06 ),74F os 0.02 8. 90E-2
- 1.77E-11 3.7sh-09 6.05E-ca 1.31E-07 2.11 E- 07 3.2?t 07 5.4tE-06 6.42F-07 1.13t-66 2.47F~06 3.69E-06 7.201-06 0.05 1.60E-13 4.34E-09 5.31E-03 2.13E-07 3.61E-07 5.38E-07 7.ssE-07 1.04E-05 C7 1.51F-06 2.61E-06 5.56E-06 8.25F-06 1.57E-05 2.24E-05 0.10 5.07E-11 3.21E-08 1.61E-07 4.44E-07 7.11E-07 1.03E-06 1.47E-06 2.72F-06 C) 0.20 9.98E-10 9.7 3 E-0 8 3.46E-07 4.58E-06 9.49E 06 1. 4 0 E- 0 5 2. toe-05 3.6SE 05 -$
8.69E-07 1.33E-06 2.86E-06 2 . 5 6 E-06 4.52F-06 1.3SF-06 0.50 6.44E-09 2.57E-07 8.41E-07 1.97E-06 1.482-05 2.16 E 's5 3.90t-05 5.42E-05 2.81E-06 3.632-06 4.71E-06 7.6 9E- 06 1.20E 05 37 1.00 1.39E-08 4.99E-07 1.58E-06 3.42E-06 2.29E-05 3.32E-05 5.78F-05 7.95E-05 4.49E-06 5.41E-06 6.71E-06 1.01E 05 1.56E-05 2.89E-05 4 2.00 2.72E-08 9.40E-07 2.83E-06 5.46E-06 6.53E-06 7.412-06 *B.76E-06 4.17E-05 7.14E 05 9.77E-05 ;j 5.00 1.28F-05 1.90E-05 3.42E-05 4.93E-05 8.34E-05 6.39E-08 2.00E-06 5.39E-06 8.70E-06 9.31E-06 9.87E-06 1.12E-01 1.14E-04 10.00 1.16 E- 07 3.22E-06 7.80E-06 1.12k-05 1.11E-05
- 1. 56 E-0 5 2.26E-05 3.99E-05 5.74E-05 9.6 3 E- 05 1.312 04 1.14 E - 6 5 1.26E-05 1.72E-05 2.46F-05 4.31E-05 h) 6.206-03 1.04E-04 1.41E-04
}
Emitted phetos emer87 IMeV) n 3 e 0.500 0.600 0.800 {} 1.000 1.503 2.000 3.000 4.000 5.000 (1/:al' 6.000 8.000 10.000
})
ri 0.01 7 05E-06 8.48E-06 1.19E- 0 5 1.49E-05 2.23E-05 2.96E-05 4.31E-05 5.57E-05 6.75E-05 H 0.02 1.34E-05 1.65E-05 2.24E-05 2.80E-05 4.14E-05 5.43E-05 7.80E-05 9.99E-05 1.20E-04 7.89E-05 1.01E-04 1.21F-04 C) 0.05 2.87E-05 3.50E-05 4.70E-05 5.81E-05 8.412-05 1.09E-04 1.52E-04 1.92E-04 2.30E-04 1.40E-04 1.78E-04 2.14 E- 04 ) 0.10 4.65E-05 5.6 2 E-0 5 7.4 7E-0 5 9.35E-05 1.30E-04 1.66E-04 1.2 9E-04 2.65E-04 3.33E-04 4.00E 04 2.85E-04 3. 3 9E- 04 3.89P-04 4.87E 04 5.82E-04 0.20 6.852-05 8.222-05 1.08E 04 1.31E-04 1.84E-04 2.32E-04 3.15E-04 3.91E-04 4.61E-04 5.28E-04 4.58F-04 0.50 9.97E-05 1.196-64 1.55E-04 1.87E-04 2.59E-04 3.23E-04 4.35E-04 7.86F 04 1.00 1.22E-04 5.15E-04 6.30E 04 7.18F - 0 4 8.93E-04 1.07F 03
- 1. 4 5E- 04 1.89E-04 2.28E-04 3.13E-04 3.90E-04 5.22E-04 6.40E-04 7.52F-64 2.00 1.42E-04 1.69E-04 2.20E-04 2.64E-04 8.57F-04 1.06E 03 1.27E 03 3.63E-04 4.50E-04 6.01E-04 7.36E-04 8.64E-04 5.00 1.642-04 1.95E-04 2.53E-04 3.042-04 4.17E-04 9.84E-04 1.22E-03 1.46E-03 5.17E-04 6.89E-04 8.4 2 E- 0 4 9.48E 04 1.12E-03 1.39E-03 10.00 1.76E-04 2.10E-04 2.72E-04 3.27E-04 5.56E-04 1.66E-03 4.49E-04 7.39E-04 9.03E-04 1.06E-03 1.20E-03 1. 4 9E- 03 1.7BE-03
- 8estprocal of tha ratasstion leegth for the esposential distributies 9 9 8 .
i O O Exponentia! source distributions D. C. KOCHER and A. L FlOREEN 2M Finally, we consider the dose-rate factor for particular body organs of individuals exposed i sources w hich are exponentially distributed with to the spectnam of photons emitted by panicular radionuclides. depth in soil. This source distribution has been
} i For energy E, and any depth of the sources i used to oesenbe measured concentrations of in soil, the dose-rate factor for body organ k is ! fallcut from atmospheric weapons testing related to the dose-rate factor in air at the ! (Be68a), and it may be appropnate for the location of the exposed individual by the equa-general case of chronic depositions of radionu- tion
[ clides omo uudisturbed soils. For an exponential distribution, the source DRF/(E,) = DRF/(EJG/(E,1. l concentration as a function of depth in soil is t12)
; gisea by
, where G/ is defined as the ratio of the dose Ux) = xo exp( ax), (!I) rate in the kth organ to the dose rate in air for >
energy E,. Values of G/ hase been calculated where xo is the concentration at the ground only for immersion in a semiinfinite armo-surface and a is the reciprocal of the relaxation spheric cloud source, so that this ratia is usually length; t.c.1/a is the depth at which the con- assumed to be independent of the mode of centration is reduced by 1/e of its value at the exposure (Ko80; Ko81a; KoS3a; Ko83b). Thus, surface. T he limiting cases a = 0 and a = ' for exposure to sources on the ground surface correspor.d to a uniform source distribution and or in soil, the values of G/ for 24 body organs '
; a plane source at the ground surface, respec- and 15 photon energies between 0.01 and 10 tively. hieV can be estimated by dividing the organ The dose-rate factors calculated from eqns dose-rate factors foi air immersion in Table 2 (5), (6) and (11) for exponentially distributed of Kocher (Ko83a) by the corresponding dose-j sources in soil are given in Table 3. For an rate factar in air for a semi-infinite atmospheric y aregl concentration of activity in soil of 1 Bq/ cloud, i.e. the so-called air kerma. The air cm , the surface concentration xo m eqn (11) is kerma is given by (1/2)KE,/p.,, where K is numerically equal to a. The rewlts in Table 3 defmed with eqn (2) and p, is the density of air
; apply to a height of I m above ground. Thus, in g/cm).
as described with eqn (6), the upper boundary For example, for immersion in a semi-infmite 3 of the :.ource region is set equal to 0.1 cm for cloud source of 1-MeV photons, the dose-rate g all photon energies. The term m the dose-rate factor for total body (Ko83a) is 1.24 Sv/a per e
;; 3 factor equation involving an integral over the Bq/cm and the air kerma is calculated as product of the exponential source distribution descdbed above as 1.95 Gy/a per Bq/cm ,3 Thus,
; and the first-order exponential mtegral in eqn the value of G/ for this body organ and photon
,3
($) was evaluated numerically using Laguerre energy is 1.21/l.95 = 0.63. The example dose-integration (Ab65; Go69). The results m Table rate factors in air for 1-MeV photon sources in y 3 for energies between 0.2 and 3 Me\ and a soil which were calculated in previous sections between 0.1 and 10 agree within about 5% with of this paper then can be multiplied by the
- the previous calculations of Beck and de Planque factor 0.63 to obtain the dose-rate factors for 3 iBe68a). total body. Similar considerations would apply i to any other body organs and emitted photon
; energies. Values of G/ are also given in the ,
j [* DOSE-RATE FACTORS FOR BODY ORGA.NS AND PARTICt;f_AR RADIONOCLIDES documentation for the DOSFACTER compute-
; code (Kodla). !
in this section, we demonstrate how the dose- j
.; The dose-rate factors for particular radionu- ; rate factors in air above ground for monoener- .clides are obtained from the values for mono- ,
getic photon sources in soil, as calculated in i, . j this paper, can be applied to the problem of energetic sources by assuming that the spectrum i' interest in environmental dose assessments; of photons from radioactiva decay consists en-'j namely, the estimation of dose-rate factors for tirely of discrete y and x rays. Therefore, for any depth of the sources in soil, the dose-rate O: O ' L
o . R 204 DOSE-R ATE COWERSION FACTORS O factor for body organ k and a parttcular radio- ties in the calculated dose rate factors them-nuchde is gisen by seh es. The calculations in this paper have shown i DRFf = Z fsDRFME,.jG,W.,). (13) that an accounting of the shielding provided by l , soil can result in sisniftcant reductions in exter-nal dose compared with the usual assumption ' where 1, is the intensity of the tth photon of that radioruclides which are deposited on the energy E, in number per decay and the sum- gr7und surface remain there until removal by mation includes all photons in the decay spec. radioactive decay. Therefore, to tne extent that trum. external dose from sources deposited on the Application of eqn !!3) without the term G/ ground is an important pathway for an ensiron-would gise the dose-rate factor in air for the mental dose assessment, the reduction in dose panicular radionuclide. Dose-rate factors in air as radionuclides migrate downward in soils for a number of radionuclides which are as. should be incorporated into the assessment. surned to be exponen:i' ally distributed in soil have been calculated by Beck (Be80). REFERENCES Abe5 Abramowitz M. and Stegun E A. (Editorst CONCLUsiO%s 1965. "Numencal interpolation, ddferentiation. and This paper has presented calculations of dese- integration". in: //andbook at J/athematical Func. tmns p. 877 (New (ork: Doser Presst 4 rate consersion factors for external exposure to Be68a Beck H. L. and de Planque G.,1968. The photon emitters in soil. Dose-rate factors were Raduaion Field in Air Due to Distnbuted Gamma. calcubted for infmite, uniformly distributed Ray Sources in the Ground. Health and Safety plane sources of monoenergetic photons at var. Laboratory, U.S. Atomic Energy Commission, New ious depths in soil. The results were then applied York, NY, HASL-195. to the calculation of dose-rate factors for uri, Be68b Berger M.1,1968, " Energy deposition in formly contaminated slab sources in soil and water by photons from point isotropic sources . I for sources which an. exponentially distributed A ucl JIed. Suppl.1,15. wtth depth. External dose rates in air above Be80 Beck H. L.,1980. Exposure Rate Conversmn ground can be obtained by multiplying the FactorsJbr Radionudides Deposued on the Ground, dose-rate facters by a known source concentra- Ernironmental Measurements Laboratory, U.S. Department of Energy. New York. NY, EML-378. tion which is obtained, for example, from a Ch68 Chihon A. B.,1968, " Broad beam attenua-known quantity .of activity deposited on the tion", in: Engmeering Compendium on Rad:ation ground and models of radionuclide transport in Shieldine Vol 1 (Edited by R. G. Jaeger), p. 202 soil. The precedure for converting dose rates in (New York: SpringerNerlag). air from monoenergetic sources to dos cates in C169 Clark F. H.,1969, " Gamma-ray buildup fac-body orgars ofindividuals exposed to a spectrum nd, air, and wood (cellulose)", Auct of photons demonstra ted. t' rom radioactive decay has also been Ed5 Eisenhauer C. M. and Simmons G. L "Pomt isotropic gamma-ray buildup factors in The methods used to calculate the dose-rce concrete", Nuct Sa Ene 56,263. factors involve idealized assumptions concerning Ga65 Gautsetsi W, and Cahill W. F.,1965, "Ex-vertical and lateral distributions of sources in ponential integral and related functions", in: soil and the extent of shielding provided by the Handbook of 3/athematical remetmns (Edited by air above ground. These assumptiors undoubt. M. Abramowitz and L A. Stegun), p. 227 (New edly are not strictiv valid for most realistic York: Dover Press). cxpcsure situations. ilowever, in evaluating the Go69 Golub G. H. and Webch J. H.1969, " Cal-validity of the results for applicatiori to environ- [.la[ n f Gaussian quadrature rules", 3/ath. mental dose assessments, it should be borne in Hur > Hi bbell i H.,1969, Photon Cross Sectrons, mind that uncertainties in predicting radionu. clide deposition rates onto the ground surface Attenuar on Coefcients, and . Energy Absorption and subsequent downward migration in soil are Coe#cte *ts from 10 kev to 100 GeV, National Bureau of 5tandards Report NSRDS NBS 29 likely to be more important than any uncertain-(Washington, DC: 11S. Department of Comme e). O
< , . -U'
a ln ! ! D C. LOCHER and A. L SJOREEN 205 LJ rs them. Kow KMc D C.. leo. "D#c rate conversion (Lusembourg: Cominission of the European Com-txtars or esternal eywure to pheten and electron muniacst ! show n r diation from radenuchdes occurnng in r utine Sp4 Sjoreen A. L Kocher D. C.. Killough G G. I nided by roca ,es from nudear fuel c> de facihties",1/cair and Nii!!er C. W. D83. 3/LSO/L and DFSOll-P >h C mruter Codes to Esn na:e EM!ne Graund umption Nosla Kacher D C.,1981. DwRate Cenerswn Suna:e Cweiratwrn for Dme Comrutv ont
& r L i ern.P Eapemre to Photons and Oak Ridge National Laboraton. Oak Ridge. TN.
on the 73. ron t Oak Ridge Nanonal Laboiators, Oak ORN L-5974 Dd DF Ridee. TN. NUREG CR 1913. ORNL/NUREG- Sm32a Smah C. B. Egan Jr D L. Wilhams tent that 3- W. A., Gruhlke J. N1. Hung C.-Y. and Senni B on the Ko81b Kccher D. C. and Eckerman K. F.,19S !. '" . Populanen Rish frem Dnposal e/High.
,,n s t ro n Lerel Radioactise it'ast:s m Geva,rc Reroutories.
! .. Electron dme rate consersion factors for esternal
) in dost. esposure of the skin Heaah P/nT 40. th e . EPA 520/3-80-006 (Washington. DC. U.S. Ensi-
,I in soi!s ranmental Protection Agenen Kc83a Kos her D. C. 198 3. " Dose.ra'e cons ersion Sm32b Smith J. NI , Fowler T. W. and Goldin ment. factors for esternal exposure to photons and elec- A. S. 1982 Enuronmental Pathwar Afode/S lor i trans", Health Pin s. 45, b65. 5, popuja,wn yfe,j;g g,q.Wrom Dispoul Ko43b Kocher D. C.1981 "Extcrnal dosimetrs" o.' //reh-L'esel Radmactne it'ane m Geolocc Re-
' E '!" '
in: Radw/cgical A ssessment (Edited by J. E. Till roatories. EPA 520/5 50-002 (Washiraton. DC: ui n
,' * [nd "
and H. R. Nic>erk Chap. S (Washington, DC: U.S- U.S. Ensironmente' Protection Agency). Nuclear Regulatory Commissionk Tr66 Trubey D. K.,1966. A Surver of Eminnca/ 79g y, NASbs Natnonal Academy of Sciences-National Funcnon.: Used :o Fit Gamma-Rav Bwidup Fa.
/ Gamma- Rm rch Council IM Studet m Penetration of. tors. Oak Ridge National Laboratory, Oak Ridge.
g 3,g Chamed Paracles m .Wtter. Pubhcation i133 TN. ORNL-RSIC 10. sion, Ne; M shington DC: Nanonal Academy of Sciences). L'SN RC77 U.S. Nuclear Regulatory Commission, NRPB79 Nanonal Radiological Protection Board 1977. "Calculatan of Annual Doses to Ntan from asition in and Commissanat a FEnergae Atomique, 1979 Routine Releases of Reactor Ef!luents for the Pur-urces".1 Alei h do/ m /W Esaluanne the Radu>loccal Con- pose of Evaluating Comphance with 10 CFR Part p >coences of Rasiwactne Efn.ents Released .in 50. Appendix I", Regulatorv Gnade 1.104 (Wash-
. on g,/n -- 4 Norma! Operanons. Doc. No V/3865/79-EN.FR ington, DC: U.S. Nuclear Regulatorv Commissionk 1e Ground.
pory, U.S. ENtL 378. f Radia:wn attenua-irt p.202 nildup fac-m )" Nuci L 1975. factors in 965, "Ex. ons", in: Edited bs - t i 227 (New i 969, " Cal-s". Math i s Sections. l: bsorpaan National .
' N35 29 < mmerce).
in s
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J
d 4 i 4 , , . . 4 , O 1 l S Boston Edison Company i I Application For Approval For Onsite Disposal Of Slightly contaminated Soil -- Attachment III i i )
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- 400 - SECTION 4 A' * *t00 200 j ,M s
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eu m f.h:li... . a5 LEGEND '* Existing Water Welt. Numeen in cross references Tabia 2-23 "h Pond: Shows elevation of water surf ace from U.S.G.S. Quadrangte
,,4 Pond: Shows elevations of next lower and higher cantours f rom U.S.G.S. Quadrangle, s**.** 0 Crancerry bog;Shows elevations of next lower and higher contaurs from U.S.G.S. Quadrangle.
l -
.- Surface water drainage divide.
BASE: U. S.G.S. 7%' Quadrangles: Manomet, Mass. (1962) and eastern part of Flyrnoutn, Mass; (1962) 1:24000, contours interval - 10 feet. I
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