ML20040D147
| ML20040D147 | |
| Person / Time | |
|---|---|
| Issue date: | 05/31/1979 |
| From: | NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | |
| Shared Package | |
| ML20040D143 | List: |
| References | |
| RTR-REGGD-3.051, TASK-OS, TASK-RH-802-4 REGGD-03.XX, REGGD-3.XX, NUDOCS 8201300324 | |
| Download: ML20040D147 (69) | |
Text
-
, A:
~
May 1979
~
i Division 3 Task RH 802-4
~
6 DR!ff 9
[a 9
h CALCULATIONAL MODELS FOR ESTIMATING RADIATION DOSES TO MAN FRCM AIRBORNE RADI0 ACTIVE MATERIALS RESULTING FROM URANIUM MILLING OPERATIONS A
I h
l j e
8201300324 020112 o[yhk PDR
{
_-)
ka6u I
DRWf TABLE OF CONTENTS
_Page A.
INTRODUCTION........................
1 B.
DISCUSSION.........................
1 1.
Uranium Mill Source Terms...............
2 2.
Critical Exposure Pathways...............
3 3.
Required Dose Estimates................
3 3.1 Individual Doses.................
3 3.2 Population Doses.................
5 4.
Use of This Guide...................
6 C.
REGULATORY POSITION 7
1.
Concentrations in Environmental Media.........
8 1.1 Radionuclide Accumulation on the Ground......
8 1.2 Total Air Concentrations.............
10 1.3 Vegetation Concentrations.............
12 1.4 Heat and Milk Concentrations...........
14 1.5 Concentrations at Different Times.........
14 2.
Dose Calculations for Individuals...........
16 2.1 Inhalation Doses.................
16 2.2 External Doses..................
18 2.3 Ingestion Doses..................
19 2.4 Individual Dose Totals..............
20 3.
Population Dose Calculations..............
21 3.1 Regional Population Doses.............
21 3.2 Continental Population Doses...........
25 3.3 Total Po,pulation Dose Commitments 26 D.
IMPLEMENTATION........................
28 REFERENCES 41 LIST OF SYMBOLS.........................
44 APPENDIX A - Site-Specific Information and Data Used by the NRC Stan in Performing Radiological Impact Evaluations for Uranium Milling Operations.................
52 iii
um DRAFf TABLE OF CONTENTS (Continued)
P.32 APPENDIX B - Staff Methodology for the Computation of 100-Year Environmental Dose Commitments...............
57 APPENDIX C - Radon Dose Conversion Factor............
60 REFERENCES FOR APPENDIX C....................
61 VALUE/1MPACT STATEMENT......................
62 iv
-__--______.m_
.t
' rKs:
00]J'I r7 LIST OF TABLES Table P_ag 1
Isotopes end Particle Sizes for Which Direct Air Concen-t' rations (C values) are Required as Input Data....
28 aidp 2
Environmental Transfer Coefficients............
29 3
Inhalation Dose Conversion Factors............
30 4
Dose Conversion Factors for External Exposure.......
31 5
Food Consumption Rates Used for Calculating Doses to Individuals........................
32 6
Ingestion Dose Conversion Factors.............
33 7
Average Agricultural Productivity Factors for Various States..........................
34 8
Food Consumption Rates Used for Calculating Doses to Populations........................
35 9
Age Distribution of Population, Average and Per Capita Consumption Rates, and Fractions Used in the Absence of Site-Specific Data....................
36 10 Continental Population Doses per kCi* of 222Rn Released in 1978...........................
37 11 Projected Population of the United States, 1978-2100...
38 12 Conversion Factors into SI Units............. 40 l
A-1 Plant, Plant Operations, Meteorological, and Environmental Data Routinely Used by the NRC Staff in Performing Radi-ological Impact Evaluations...............
53 B-1 Comparison of Staff and Conventional Techniques for i
Environmental Dose Commitment Calculation........
59 LIST OF FIGURES Figure M
1 Schematic Diagram of Information Flow and Use for Dose Calculations.......................
39 i
a See Table 12.
v
~
,,j.f.,
r at :.
~
DRAff A.
INTRODUCTION Analyses of radiation doses to the public, or individual members thereof, resulting from the radioactive effluents from uranium mills are required to be made by the NRC staff for the following purposes:
1.
Evaluating compliance with 40 CFR Part 190, "Envirorimental Radiation Protection Standards for Nuclear Power Operations,"
2.
Evaluating compliance with the "as low as is reasonably achievable" (ALARA) criterion embodied in 10 CFR Part 20, " Standards for Pro-tection Against Radiation," and 3.
Evaluating overall radiological impact as part of the complete environmental impact assessment required by the National Environ-mental Policy Act (NEFA) of 1969 (Public Law 91-190, 83 Stat. 852).
This regulatory guide describes basic features of calculational models employed by the NRC staff for such evaluations and suggests values for various parameters used in the estimation of radiation doses to man from uranium milling operations.
Specifically, this guide addresses the calculation of radiation doses to man from previously estimated environmental radioactivity concentrations in air.
The environmental radioactivity concentrations in air required for this calculation result from extensive and detailed analyses ofeffluentreleaseratesandatmospericdispersionphenomena.
Information kthe approach or estimating source terms is included in the l
Final Generic Environmental Impact Statement on Uranium Milling, NUREG-0706 l
l (Ref. 1).
The methodology used by the staff for calculating atmospheric dis-persion is documented in the MILDOS code user's manual, NUREG/CR-2011 (Ref. 18).
B.
DISCUSSION This guide describes rodels used by the NRC staff to estimate the radi-ological impacts resulting from uranium mills for the purpose of evaluating-compliance-with 40 CFR Part 190 and 10 CFR Part 20 as well as assessing over-all environmental radiological impacts in accoraance with NEPA.
J i
i 1
i
_. _ _.. _ _ =,... _. _.... -
,m.
ud:
) /
1.
URANIUM MILL SOURCE TERMS
[gd I A' uranium mill, unlike other types of fuel cycle f goes through phases in its life cycle in which both the composition and the magnitude of its radioactive emissions (and associated impacts) vary greatly.
For this reason, the NRC staff will perform impact evaluations for each individual mill at different stages of its existence.
Typically, a uranium mill will operate for a period of years during which there will be radon and particulate releases from the ore storage pile, the mill itself, and the tailings disposal area.
During this operational period, both particulate and radon releases from the tailings pile may be somewhat limited by maintaining the pile at least partially under water.
Mechanical sprinkler systems or chemical stabilizing agents may also be used to inhibit air suspension by wind action of radioactive tailings dust.
Upon the cessation of actual milling, the tailings pile is normally allowed to dry by process of natural evaporation until it is ready for stabili-zation.
In this postoperational, prestabilization period, there are essentially no releases from the ore storage pile or the actual mill.
However, as the tail-ings pile dries, releases of radon and particulates from this source may increase, reaching a maximum prior to implementation of measures required to achieve long-term stabilization.
After stabilization and reclamation of the tailings area, there should be no further radioactive particulate releas However, small quantities of radon may continue to diffuse upward from the tailings and may be released to the atmosphere. These continuing radon releases, though small, will likely persist for tens of thousands of years.
Depending on the specific details of the site, facility, effluent controls, and stabilization program, maximum individual particulate exposure could occur either during the last year of actual milling or the last year prior to stabili-zation of the tailings.
Maximum individual doses due to radon releases are i
likely to occur during the last year prior to stabilization.
The radioactive isotopes comprising uranium mill radioactivity releases are mostly those belonging to the 2ssU and 2ssu decay series.
The 2ssU series j
members amount to less than 5 percent of total releases and are routinely dis-l regarded because of their insignificant contribution to overall radiological impact.
2 i
di BRAFT 2.
CRITICAL EXPOSURE PATHWAYS Exposure pathways of concern for airborne releases from uranium mills normally include inhalation of airborne radioactive material, ingestion of vegetable and animal products contaminated via deposition, and direct external exposure to radiation emitted by airborne activity and activity deposited on ground surfaces.
Liquid exposure pathways are not usually of concern because there are usually no discharges to surface water of liquid effluents.
Liquid pathways may exist, however, and methodology similar to that used in Regula-tory Guide 1.109, " Calculation of Annual Doses to Man from Routine Releases of Reactor Effluents for the Purpose of Evaluating Compliance with 10 CFR Parc 50, Appendix I" should be used for evaluating intakes via the liquid pathway.
How,
ever, ingestion dose factors from Teble 6 should used in converting intakes to doses.
All individual exposure pathways of significance will be evaluated at loca-tions where the exposure pathway and a dose receptor actually exist at the time the analysis is made.
Also, the applicant may take into account any real phenomena or actual exposure conditions that may be present.
Such conditions could include actual values for agricultural productivity, dietary habits and food sources, residence times, measured environmental transport factors, or similar values determined for a specific site. However, if the analysis is based on existing conditions and if potential changes in land use and food pathways could result in exposures significantly higher, the applicant should provide reasonable assurance that a monitoring and surveillance program will l
be performed on a regular and continuing basis to determine if such changes have occurred.
l 3.
REQUIRED DOSE ESTIMATES l
l 3.1 Individual Doses Evaluations of the dose received by an exposed individual are made to satisfy the requirements of both 40 CFR Part 190 and 10 CFR Part 20.
The EPA regulation, 40 CFR Part 190, speaks to individual radiation doses from all pathways and all nuclear power and fuel cycle facilities combined, except that exposure from radon and its daughters need not be included.
10 CFR Part 20 includes a requirement to keep all radiation exposures "as low as is reason-ably achievable" (ALARA).
ALARA is a general concept that has not to date i
3
A DRE been interpreted in the form of numerical design objectives for uranium mills as it has for light-water-cooled nuclear reactors (see Appendix I, " Numerical Guides for Design Objectives and Limiting Conditions for Operation to Meet the Criteria 'As low As Is Reasonably Achievable' for Radioactive Material in Light-Water-Cooled Power Reactor Effluents," to 10 CFR Part 50, " Domestic Licensing of Production and Utilization Facilities").
However, a case-by-case evaluation will be made to ensure that doses are kept as low as is reasonably achievable.
ALARA evaluations will address all releases, includ-ing radon and its daughters, and will consider population doses as well as individuel doses.
For the purpose of evaluating compliance with 40 CFR Part 190, the whole body and organ doses to any individual, considering all pathways combined, from all activity releases except radon and its daughters are evaluated for:
a.
The last year of actual mill operation, and b.
The last year prior to tailings pile reclamation.
These evaluations are adequate for assessing ALARA compliance except that exposure to radon and its daughters is to be included and radon and daughter exposure for the first year after tailings pile reclamation is also to be evaluated.
Postreclamation exposure to radon and its daughters is to be evaluated at the location of greatest radon concentration where unrestricted land use after mill decommissioning may be permitted.
Exposed individuals are characterized with regard to food consumption, occupancy, and other uses of the region in the vicinity of the mill site.
l All physiological and metabolic parameters for the exposed individuals are assumed to have those characteristics that represent the averages for the various age groups in the general population.
Although specific individuals will almost certainly display dietary, recreational, and other living habits l
considerably different from those suggested here and actual physiological and metabolic parameters may vary considerably, the NRC staff considers the use of these reference values to be acceptable because the actual physio-logical and metabolic characteristics of specific individuals cannot usually be determined.
Applicants are encouraged to use information and cata appli-cable to a specific region or site when possible. Where site-specific infor-mation and data are used, its origin or derivation should be documented for the NRC staff's review.
4
..a..
'uIf.. ' -
DMi In this guide, the term " dose" is used instead of the more precise term
" dose equivalent," as defined by the International Commission on Radiological Units and Measurements (ICRU).
When applied to the evaluation of internal deposition of radioactivity, the term " dose," as used here, includes the prospective dose component arising from retention in the body beyond the period of environmental exposure, i.e., the committed dose equivalent.
The committed dose equivalent is evaluated over a period of 50 years.
The committed dose equivalent per unit intake, either by inhalation or ingestion, usually varies by age as well as by organ.
For the purpose of calculat'ing collective (population) doses, the population has been assumed to be composed of four age groups:
infants (0 to 1 year), children (1 to 11 years), teenagers (11 to 17 years), and adults (17 years and older).
Four sets of ingestion-dose conversion factors are presented later in this guide, one for each of these four age groups.
Available data are not suffi-cient to permit the calculation of age-specific dose conversion factors for inhalation exposure, and adult dose conversion factors are assumed to apply for all age groups for this exposure pathway.
3.2 Population Doses Evaluations of population doses resulting from uranium milling opera-tions are required to satisfy NEPA stipulations with respect to assessing the total environmental impact associated with the operation of each facil-ity.
Calculated estimates of resulting population doses therefore need to reflect, insofar as practicable, the overall radiological impact of each uranium mill over the duration of its existence.
For a typical uraniurr. mill life cycle, the total radiological impact is composed of the impacts of the three major phases of existence:
the operational phase, the postoperational prereclamation phase, and the post-reclamation phase.
The first two phases say involve substantial releases of radon gas and particulates but are of relatively short duration.
The postreclamation phase involves only small releases of radon, but these releases may persist for periods of tens of thousands of years.
For each separate mill life-cycle phase, the average annual radiological impact will be estimated by the NRC staff by use of the following basic procedure:
5
lLi'..
r l
b]~I a.
Annual average releases over the duration of the particular mill phase will be estimated for each isotope.
b.
The radiological impact resulting from 1 year of average releases will aluated in terms of population dose, using the EPA con-cept of " environmental dose commitment" (Ref. 3).
The environmental dose commitment will be evaluated for a period of 100 3 ears follow-ing release as per the procedure used by EPA in setting the stand-ards in 40 CFR Part 190.
The total dose commitments for the operational and prereclamation phases will be' calculated by multiplying the annual population dose commitments by the number of years the mill is expected to be in each phase.
The sum of these two products then represents an approximation of the combined radi-ological impact of the facility prior to tailings pile reclamation.
The annual population dose commitments from postreclamation radon releases are also calculated and represent the continuously recurring impact of this residual activity source.
Consideration of particulate releases will generally be limited geograph-ically to the area within 80 km (50 mi) of the mill site. Within this area, exposure pathways requiring assessment include all those considered in the evaluation of maximum individual exposure.
Outside the 80-km (50-mi) radius, only radon and daughters require consideration and thece are treated separately from particulate releases (see Section 3.2).
4.
USE OF THIS GUIDE Present NRC staff practice with regard to the calculation of radioactive emission rates from uranium milling facilities involves the enaracterization of such releases by radionuclide, particle size, and density (Ref. 1).
The data required as input for use of the calculational models described in this guide consist of annual average air concentrations resulting directly from such releases at specific locations (not including resuspended air concentra-tions of radioactive materials previously deposited on giaund surfaces).
The required input air concentrations are denoted in this guide, for a particular 3
location, by the symbol Cadip (in pCi/m ), where the subscripts indicate air 6
a.d.J 1
1 l
concentration (a), direct (d), radionuclide (i), and particle size (p).
Direct l
air concentrations required are those for values of the subscripts i and p as identified and defined in Table 1.
The primary calculational tool employed by the staff in performing radi-ological impact evaluations of uranium milling operations is the MILD 05 code, i
Ref. 18), a modified version of the Argonne National Laboratory Uranium Dis-persion and Dosimetry (UDAD) Code (Ref. 2).
In the N.lC staff code, MILD 05, only five primary radionuclides in the 238U decay chain are treated explicitly as source terms.
These radionuclides are 23sU, 2soTh, 22sRa, 21oPb, and 222Rn.
Release rates for these radionuclides are required for each potential onsite source (for particle sizes 1 through 4 in Table 1).
For 222Rn daughters, which grow in during transport of 222Rn from the site, the resulting ingrowth concentrations (particle size 5 in Table 1) are also required.
These 222Rn daughters include 21spo, 214Pb, 214Bi, stoPb, and 21oPo.
The dosimetry model accounts for releases and ingrowth of other radionuclides, using assumptions of secular equilibrium.
Appendix A identifies and describes the various other site-specific information and data routinely used by the NRC staff in performing radio-logical impact assessments for uranium milling facilities.
Appendix B pro-vides a more detailed discussion of the method used in this guide for calcu-lating environmental dose commitments. Appendix C provides a detailed explanation of the derivation of the radon dose conversion factor used in this guide.
C.
REGULATORY POSITION Equations and other data by which the NRC staff will estimate radiation exposure for individuals and the population in general are presented below.
These equations are appropriate for the exposure pathways that the staff routinely considers in its evaluations.
In addition, other pathways that may be present because of unique conditions at a specific site should be considered if they are likely to provide a significant contribution to total dose. A pathway is considered significant if a conservative evaluation yields an additional dose increment of more than 10 percent of the total from all other pathways considered in this guide.
7
WU.. ; -
DRAFI 1.
CONCENTRATIONS IN ENVIRONMENTAL MEDIA As discussed in Section B.4, annual average direct air concentrations I
are required as input data for use in the equations that follow.
These equa-tions yield resulting concentrations in environmental media of interest, including total air concentrations, ground surface concentrations, and concer-trations in edible vegetation, meat, and milk. These concentration calcu-lations are explicitly performed only for certain members of the 23sU decay chain.
Concentrations in environmental media of other chain members are inferred from those for which concentrations are explicitly calculated.
The basic calculational procedure first involves treatment of the direct air concentrations to obtain ground surface concer.trations and resuspended air concentrations.
Resuspension of radioactive materials deposited on ground surfaces is not treated as a loss mechanism for ground concentrations.
For this reason, deposition of resuspended air concentrations onto ground sur-faces is not considered.
Resuspended particulate concentrations in air are oddcd to the airborne concentrations arising directly from the source to obtain total air concentrations.
The calculated total air concentrations are then used to obtain total deposition rates onto vegetation (resuspension losses of activity deposited on vegetation are assumed to be accounted for by the application of a weathering half-life).
Total deposition rates and ground concentrations are used to compute concentrations in various vegeta-tion types, including hay and forage.
Radionuclide concentrations in hay and animal forage are initial inputs for the calculation of radionuclide concentrations in meat and milk ingested by man. This basic calculational process, the resulting environmental media concentrations, and the exposure pathways for which they are used are indicated schematically in Figure 1.
1.1 Radionuclide Accumulation on the Ground Radionuclide ground concentrations are computed from the calculated airborne' particulate concentrations arising directly from onsite sources (not including air concentrations resulting from resuspension).
Resuspended 8
l 1
Qi:.
h4 particulate concentrations are not considered for evaluating ground concen-trations. The direct deposition rate of radionuclide i is calculated,, using the following relationship:
Ddi =
C (1) adip p p
where C
is the direct air concentration of radionuclide i, particle.
adip 3
size p, in pCi/m ;
D is the resulting direct deposition rate of radionuclide i, di 2
in pCi/m per sec; and V
is the deposition velocity of particle size p, in m/sec (see p
Table 1).
The concentration of radionuclide i on a ground surface due to constant over time interval t is obtained from deposition at the rate Ddi
~
~ 1 - exp[-(Aj + A,)t]
(2) g (t) = Ddi A.+A C j 1
e where g (t) is the grou:;d surface concentration of radionuclide i at time C j 2
t, in pCi/m ;
t is the time interval over which deposition has occurred, in sec; A,
is the assumed rate constant for environmental loss, in sec 1; and A
is the radioactive decay constant
- for radionuclide i, in j
sec 1 The environmental loss constant, A,, corresponds to an assumed half-time for loss of environmental availability of 50 years (Ref. 1).
This parameter dCCounts for downward migration in soil and loss of availability due to chemical binding.
It is assumed to apply to all radionuclides deposited on the ground!
Ground concentrations are explicitly computed only for 2380, 230Th, 22sRa, an 3 21oPb.
For all othe: radionuclides, the ground concentration is ARadiological decay constants employed by the NRC staff are obtained from data given in Reference 4.
9
g i
assumed equal to that of the first parent radionuclide for which the ground concentration is explicitly calculated.
For 21oPb, ingrowth from deposited 22sRa can be significant.
The concentration of 21oPb on ground due to 22sRa deposition is calculated by the staff, using the standard Bateman equation and ignoring the very short-lived daughter radionuclides.
This is equiva-lent to assuming that 22sRa decays directly to 21oPb.
Using i = 6 for 22sRa and i = 12 for 21oPb (see Table 1), the following equation is obtained:
12 d6 1-e-A$2t
,-Agt
,-Aypt A D p
Cg12(Pb Ra) =
Ag Aj2 A$~A52 where Cgyp(Pb Ra) is the incremental 21oPb ground concentration resulting from 22sRa deposition, in pCi/m ; and 2
A*
is the effective rate constant for loss by radioactive n
decay and migration of a ground-deposited radionuclide and is equal to A
- A, in sec 1 n
e
- 1. 2 Total Air Concentrations For use of the models described in this guide, air concentrations arising directly from onsite sources are required for each receptor location as a function of particle size (for particulates).
Direct air concentrations are assumed to include the effects of depletion by deposition (particulates) or ingrowth and decay in transit (for radon and its daughters).
In order to compute inhalation doses, the total air concentration of each radionuclide i
I at each location (as a function of particle size) is computed as the sum of the direct air concentration and the resuspended air concentration:
C,$p(t) = Cadip + Carip(t) k (4)
~
where C
is the calculated direct air concentration of radionuclide i, adip 3
particle size p, (constant), in pCi/m ;
C,$p(t) is the calculated total air concentration of radionuclide i, 3
particle size p, at time t, in pCi/m ; and 10
e, bl i
Carip(t) is the calculated resuspended air concentration of radionu-3 clide i, particle size p, at time t, in pCi/m.
The resuspended air concentration is computed using a time-dependent and particle-size-dependent resuspension factor, which, for deposits of age t years, is defined by
-A t
~
R (t) = (0.01/V )10 5 e R (for t 5,1.82 yr)
(Sa) p p
R (t) = (0.01/V )10 9 (for t > 1.82 yr)
V, (5b) p p
where R (t) is the ratio of the resuspended air concentration to the ground p
concentration, for a ground concentration of age t yr, of particle size p, in m 1; A
is the assumed decay constant of the resuspension factor R
(equivalent to a 50-day half-life), 5.06 yr 1; 0.01 is the deposition velocity for the particle size for which the initial resuspension factor value is 10 5/m, in m/sec; 10 5 is the initial value of the resuspension factor for particles with a deposition velocity of 0.01 m/sec, in m 1; 10 9 is the terminal value of the resuspension factor for particles with a deposition velocity of 0.01 m/sec, in m 1; and 1.82 is the time required to reach the terminal resuspension factor, in yr.
The basic formulation of the above expression for the resuspe$sion factor, the initial and final values, and the assigned decay constant.ierive from experimental observations (Ref. 1).
The decrease with age primarily accounts for agglomeration with other larger particles.
The inverse relationship to deposition velocity physically accounts for decreased resuspendibility of larger particles; mathematically, it eliminates mass balance problems for the 35 pm particle size.
Based on this formulation, the resuspended air concentration is given by 4
.. 3
-J :.
DRAFT 1-exp[-(Ay+A)(t-a)]
R 10 5 Carip(t) = 0.01Cadip (gj,g) p
~
exp[-Aj(t-a)]-exp(-Ayt)
+ 10 4 6(t)
(3.156 x 107) 6)
g) where a
is eque.1 to (t - 1.82) if t > 1.82 and is otherwise equal to zero, in yr; 6(t) is zero if t < 1.82 and is unity otherwise, dimensionless; Ay is the effective removal constant for radionuclide i on soil, in yr 1; and 3.155x107 is sec/yr.
Equation 6 yields the resuspended air concentration of radionuclide i in particle size p because of deposition over time span t, in years.
Total air concentrations are computed using Equations 6 and 4 (in that order) for all particulates in particle sizes 1 through 4 (see Table 1).
Particulate daughters of 222Rn (particle size 5 in Table 1) are not assumed to be depleted because of deposition and are also not assumed to resuspend.
1.3 Vegetation Concentrations As illustrated in Figure 1, vegetation concentrations are derived from l
ground concentrations and total deposition rates. Total deposition rates are given by the following summation:
Dj= {C,$pp (7)
V P
l where D,
is the total deposition rate, including deposition of resus-2 2
l pended activity, of radionuclide i, in pCi/m per sec.
1 i
ancentrations of released particulate materials can be environmentally trans-ferred to the edible portions of vegetables, or to hay or pasture grass con-sumad by animals, by two mechanisms -- direct foliar retention and root uptake.
12
7.1 us&-.
DWT Five categories of vegetation are treated by the staff.
They are edible above ground vegetables, potatoes, other edible below ground vegetables, pasture grass, and hay.
Vegetation concentrations are computed using the following equation:
[1-exp(-A,t) sf/
B i
y yg
+ C (8)
Cyg=DFEgry y3 gg vw p
L where B
is the soil-to plant transfer coefficient for radionuclide yg i, vegetation type v, dimensionless; C
is the resulting concentration of radionuclide i, in vegeta-yg tion v, in ;Ji/kg (wet weight);
E is the fraction of the foliar deposition *eaching edible por-y tions of vegetation v, dimensionless; F
is the fraction of the total deposition retained on plant r
surfacts, 0.2, dimensionless; p
is the assumed soil areal density for surface mixing, 240 kg/m2 (dry weight);
t is the assumed duration of exposure while growing of vegeta-y tion v, in sec; 2 (wet Y
is the assumed yield density of vegetation v, in kg/m y
weight); and A,
is the decay constant accounting for weathering losses (equivalent to a 14-day half-life), 5.73 x 10 7 sec 1 The value of E is assumed to be 1.0 for all above ground vegetation and y
0.1 for all below ground vegetables (Ref. 5).
The value of t is taken to y
be 60 days, except for pasture grass where a value of 30 days is assumed.
2 The yield density, Y, is taken to be 2.0 kg/m, except for pasture grass y
where a value of 0.75 kg/m is applied.
Values of the soil-to plant transfer 2
coefficients, Byg, are provided in Table 2.
13
w;.
. q.
DRAFT 1.4 Meat and Milk Concentrations Radioactive materials can be deposited on grasses, hay, or silage that are eaten by meat animals that are in turn eaten by man.
The equation used to estimate radionuclide concentrations in meat is Cbi = QFbi(F C j+FCh hi)
(9)
^
pg pg where I
is the resulting average corcentration of radionuclide i in bi meat, in pCi/kg; C
is the concentration of radionuclide i in hay (or other stored hi feed), in pCi/kg; C
is the concentration of radionuclide i in pasture grass, in pgj pCi/kg (wet weight);
F is the feed-to-meat transfer coefficient for radionuclide i, bi in pCi/kg per pCi/ day ingested (see Table 2);
are the fractions of the total annual feed requirement assumed Fpg,Fh to be satisfied by pasture grass or locally grown stored feed (hay), respectively, dimensionless; and Q
is the assumed feed ingestion rate, 50 kg(wet weight)/ day (Ref. 5).
The equation used to estimate milk concentrations from cows ingesting contaminated feed is C,3 = QF,9(F C j+FCh hi)
(10) pg pg i
where C,9 is the resulting average concentration of radionuclide i in milk, in pCi/L; and F,9 is the feed-to-milk transfer coefficient for radionuclide i,
~
in pCi/L per pCi/ day ingested (see Table 2).
1.5 Concentrations at Different Times Maximum doses to individuals are calculated for the last year of mill operation and for the last year prior to tailings pile reclamation.
This 14
.ud.
. - 1.
\\
w l
llI section explains the procedures used by the NRC staff to obtain annual average environmental media concentrations for these years.
In order to estimate average environmental media concentrations during the final year of actual mill operation, for an operational lifetime of T, years, the value of the time variable t appet-ing in Equations 2, 3, 4, and 6 is set equal to T, (in appropriate units). The resulting concentration values are those predicted for the end of the final year of operation and are assumed to represent average values existing over that year.
Environmental concentrations existing during the final prereclamation year result from postoperational releases and residual conta"ination due to releases during the period of mill operation.
Because direct air concentra-tions from operational releases vanish, environmental concentrations due to operational releases, at the time of reclamation, arise only from residual ground and resuspended air concentrations.
Ground concentrations at the end of the milling period are calculated using Equations 2 and 3, with the value of t set to T,,
the operational lifetime.
Residual ground concentra-tions at the end of the final prereclamation year are then determined by g (T ) = Cg$(T,)exp[-A (T )]
(11)
C g d d
where g$(T,) is the ground concentration of radionuclide i at the time of C
2 mill shutdown, in pCi/m ;
Cg9(T )
is the residual ground concentration of radionuclide i resulting d
from operational releases, at the end of the T year drying d
2 period, in pCi/m ; and i
T is the duration of time required to dry the tailings pile d
prior to reclamation, in yr.
Residual resuspended air concentrations resulting from operational releases are determined at the end of the final prereclamation year by 10J exp[-A arip(T ) = 0.01Ca_ dip d
C d
1 - exp(-A T,)
9 (3.156 x 107)
(12) l A,
l l
15 I
.s.
aw.
JWH where C
is the direct air concentration of radionuclide i in particle adip 3
size p resulting from operational releases, in pCi/m ; and Carip(T ) is the residual resuspended air concentration of radionuclide i j,
d in particle size p resulting from operational releases, at the-3 end of the T year drying period, in pCi/m.
d Ground and resuspended air concentrations resulting from postoperational releases, at the end of the final prereclamation year, are calculated using Equations 2, 3, 4, and 6 with the value of t equal to T. These con-d j
eentrati*ons are then incremented by the residual concentrations due to opera-tional releases, calculated using Equations 11 and 12 to obtain the required totals. Total air concentrations and concentrations in vegetation, meat, and milk are then calculated from the total ground and resuspended air concentrations.
2.
DOSE CALCULATIONS FOR INDIVIDUALS Doses to individuals are calculated for inhalation, external exposure-to air and ground concentrations, and ingestion of vegetables, milk, and meat.
Internal doses are calculated using dose conversion factors that yield the 50 year committed dose equivalent, i.e., the entire dose received over j
a period of 50 years following either inhalation or ingestion.
The annual doses are actually the 50 year committed dose equivalents resulting from a 1 year exposure period. The 1 year exposure period is taken to be the year (s) when environmental concentrations resulting from plant operations are expected to be at their highest level.
2.1 Inhalation Doses Inhalation doses are calculated from the total radionuclide concentration l
in air, including resuspended material.
The inhalation dose conversion factors -
I for radioactive particulate materials used in this analysis are presented in
{
Table 3.
With the exception of the dose conversion factors presented for " mass average lung," these dose conversion factors have been computed by Argonne l
National Laboratory's UDAD computer code (Ref. 2) in accordance with the Task l
16
a.
sa:
Group Lung Model (TGLM) of the International Commission on Radiological Protec-tion (Ref. 6).
Dose conversion factors for the mass average lung have been conputed by mass-averaging the UDAD-calculated dose conversion factors for the four regions of the TGLM:
nasopharyngeal, tracheobronchial, pulmonary, and lymph.
Ordinarily, the dose computed specifically for the pulmonary region is reported or presented as the " lung" dose.
For the principal lung dose contribu-tors (uraniun and thorium), doses computed for the mass average lung are slightly higher than those calculated for the pulmonary region. The net overall effect, considering all isotopes, it thus a slight increase in the reported lung dose.
In, addition to the physical characteristics of the particulate matter involved, use of the TGLM demands the assignment of a solubility class, denoted by Y (years; for slowly soluble or insoluble compounds), W (weeks; for moderately saluble compounds), or D (days; quite soluble).
Solubility classifications have been assigned on the basis of experimental data reported and summarized by Kalkwarf in NUREG/CR-0530 (Ref. 19).
These data indicate that thorium, lead, l
and polonium are 100% class Y in ore, yellowcake, or tr. lings dusts.
Radium was determined to be best characterized by the split-solubility classification 10% class D, 90% class Y.
Uranium in ore dust was determined to be 100%
class W; uranium solubility for tailings dusts was not analyzed and is assumed to be class Y.
Data for uranium in yellowcake were mixed and showed a pronounced dependence on the specific source of the yellowcake sample.
Results reported by Kalkwarf indicate a split-solubility classification is appropriate, and on review of those results (particularly those given on page 55 of NUREG/CR-0530) the staff has assumed uranium in yellowcake to be 50% class D and 50% class Y.
The computed inhalation dose conversion factors are given in Table 3.
Doses to the bronchial epithelium from 222Rn and short-lived daughters are computed based on the assumption of indoor exposure with 100% occupancy.
The dose conversion factor for bronchial epithelium exposure from 222Rn is derivcd as follows (see Appendix C for detailed basis):
a.
1 pCi/m3 222Rn in outdoor air will yield an average indoor concentra-l tion of about 5 x 10 8 Working Level (WL).*
I b.
Continuous exposure to 1 WL = 25 cumulative working level months 1
(WLM) per year.
c.
1 WLM = 5000 mrem (Ref. 7).
l n
l One WL concentration is defined as any combination of short-lived radioactive decay products of 222Rn, per liter of air, that will release 1.3 x 105 MeV of l
alpha particle energy during their radioactive decay to 21oPb.
l 17
i.
u.-
BRA 7 Therefore, 1 pCi/m3 222Rn x (5 x 10 8 m3)x(25fL) pC b
x(5000]*)=0.625mremh and the 222Rn bronchial epithelium dose conversion factor is taken to be 3
0.625 mrem /yr per pCi/m.
Inhalation doses are computed by the staff by use of the following equation':
j p
jjp(inh) b (13) d (inh) =
{C,g DCF ip where d (inh) is the inhalation dose to organ j, in mrem /yr; and j
DCFjjp(inh) is the inhalation dose conversion factor for radionuclide i, 3
organ j, and particle size p, in mrem /yr per pCi/m.
2.2 External Doses External doses resulting from exposure to air and ground activity concen-trations are computed, using the dose conversion factors presented in Table 4 and assuming 100 percent occupancy at a given location.
Indoor exposure is l
assumed to occur 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> per day at a dose rate of 70 percent of the outdoor i
dose rate, which is equivalent to a dose reduction factor for structural l
l shielding of 0.825.
The following equation is used by the staff to calculate 1
external doses:
DCF )(gnd) 4)
v d (ext) = 0.825 p C,jDCFj3(cid) + C9j j
9 w
i where 8
l C,$
is the total air concentration of radionuclide i, in pCi/m ;
d)(ext) is the external dose to organ j, in arem/yr; DCF$3(cici) is the dose conversion factor for cloud exposure for radio-8 nuclide i, organ j, in mrem /yr per pCi/m ;
l i
18
7 y.
M:
DRAFT DCF )(gnd) is the dose conversion factor for ground exposure for radio-g 2
nuclide i, organ j, in mrem /yr per pCi/m ; and 0.825 is the effective reduction factor because of structural shielding for indoor exposure periods.
2.3 Ingestion Doses Ingestion doses are routinely calculated for ingestion of vegetables and meat (beef, unprocessed pork, and lamb).
Milk ingestion doses are also computed if that pathway exists at the time of licensing.
Ingestion doses are based on environmental concentrations established using Equations 8, 9, and 10, ingestion rates given in Table 5, and dose conversion factors given in Table 6.
Ingestion doses from vegetable consumption are r. 4puted under the assumption that an average of 50 percent of the initial activity will be lost in food preparation (Ref. 5), usually involving washing, peeling, boiling, etc. The following equation is employed to compute the annual radionuclide intake via ingestion:
C (15)
Iik
- mk mi + bk bi + 0.5 { Uvk yg v
l where l
is the activity ingestion rate of radionuclide i by an ik individual in age group k, in pCi/yr; are mm (in Uyr) aM meat (in kg/yr) ingesdon rates for l
Umk,Ubk age group k; U
is the ingestion rate of vegetable category v for age group vk k, in kg/yr (wet weight); and 0.5 is the fraction of vegetable activity remaining after food preparation, dimensionless.
j Ingestion doses are then computed by I
DCFijk(ing)
(16)
C jk(i"9) * [ I d
ik A
i j
where l
jk(ing) is the ingestion dose for organ j, age c oep k, in arem/yr; d
j and l
19 n
w
. f; c4$s s
DCFijk(ing) is the ingestion dose conversion factor for 'radionuclide i, organ j, age group k, in units of mrem /pCi ingested.
2.4 _ Individual Dose Totals Individual doses are calculated by the NRC staff for purposes of evalu-ating compliance with 10 CFR Part 20 and 40 CFR Part 190.
For evaluating compliance with 40 CFR Part 190, dose contributions from 222Rn and daughters are excluded.
Total doses to individuals are calculated for both purposes using the following equation, which sums the dose contributions from inhala-tion, external dose, and ingestion:
djk(tot) = d)(inh) + d)(ext) + djk(ing)
(17) where jk(tot) is the total dose to organ j of an individual in age group k d
from all exposure pathways, in mrem /yr.
To evaluate compliance with 40 CFR Part 190, the staff will compute total doses to appropriate individual receptors, using the above equation and all other models, data, and assumptions described in this guide, except that a.
All dose contributions from radiation emitted by 222Rn, 21spo, 214Pb, 214Bi, and 214Po will be excluded, and b.
All dose co.ntributions from radiation emitted by 21oPb, 21 obi, and 21oPo formed by decay of released 222Rn will be excluded.
With reference to Table 1 of this guide, the dose contributions eliminated for the purpose of evaluating compliance with 40 CFR Part 190 include those due to any radiation emitted by (a) radionuclides for which i = 7, 8, 9, 10, or 11 and (b) radionuclides present in particle size category p = 5 (radon daughters). The staff will add to dose totals computed for evaluating compliance with 40 CFR Part 190 any known significant doses resulting from any other light-water-cooled nuclear power generating or fuel cycle facilities,,
as appropilate (excluding doses from 222Rn and its daughters as stipulated above and excluding doses from any radioactive materials released by nuclear or other facilities or operations not included under 40 CFR Part 190).
20
.a.
Gili.
}
3.
POPULATION DOSE CALCULATIONS Population doses are calculated, using the environmental dose commitment concept with an integrating period of 100 years (Ref. 3).
Under this approach, radiological impacts for a given release of activity are integrated over a time interval of 100 years following the releasa.
The 100 year environmental dose commitment resulting from average release rates over a 1 year period is computed for (a) the period of actual uranium milling and (b) the period of time after the cessation of milling during which tailings are allowed to dry prior to final stabilization and reclamation.
The NRC staff's rationale for the selection and use of a 100 year integrating period and the staff's tech-nique for computing environmental dose commitments are addressed in Appendix B to this guide.
Population doses resulting from particulate and radon releases are evalu-ated over the general region of the facility site for the first two mill-life-cycle time spans (milling operation and prestabilization postoperation phases).
For these two time intervals, and for the postreclamation era, annual popula-tion dose commitments resulting from transcontinental dispersion of 222Rn are also evaluated.
3.1 Regional Population Doses Population doses resulting from environmental radioactivity concentra-l
?. ions in the region of the site are evaluated for all exposure pathways con-sidered in the evaluation of maximum individual doses; other pathways should also be considered if they are likely to result in an increase of more than 10 percent to the total result.
Regional population dose commitments are generally computed on the basis of the population and agricultural productiv-ity within a distance of 80 k:n (50 mi).
Individual localized population centers lying beyond this distance should also be considered if their inclu-sion would_ increase the population dose estimates by more than 10 percent.
3.1.1 Inhalation and External Doses l
Inhalation and external doses are computed by the NRC staff, using the identical models, equations, data, and assumptions as previously described for individual dose calculations in regulatory positions 1 and 2 of this 21
- - +
- +, -
---e
-w,
---mv"-
n l rudi.
b guide. The procedure for calculating regional population doses from those pathways is to (a) divide the geographical site region into segments by radius and direction, (b) establish average individual doses within each segment, (c) multiply these individual doses by the estimated population lyir.g within each segment, and (d) sum over all segments.
The population distribution required is that projected for the final year of mill operation.
The appropriate population projection should be presented for each segment formed by radii extending outward from the site and bisecting the 16 compass directions (forming 22.5' sectors) and con-centric tircles drawn at distances of 1, 2, 3, 4, 5, 10, 20, 30, 40, 50, 60, 70, and 80 km.
The 13 circles and 16 radii then form a grid composed of 192 individual segments.
Average doses over the population within each segment are computed by the NRC staff along the segment directional centerline at a distance midway between the inner and outer boundaries of each annulus.
The population dose in the site region from inhalation and external exposure pathways is computed by the staff, using the following equation:
M)(inh + ext) = 10 3 P Edh(inh) + djs(ext)]
(18) s s
where djs(ext) is the average external dose to organ j in segment s, in mrem /yr; js(inh) is the average inhalation dose to organ j in segment s, in d
mrem /yr; M (inh + ext) is the resulting population dose from inhalation and external j
exposure pathways, in rem /yr; P
is the population residing in segment s; and 3
10 3 is a conversion factor from millirem to rem.
3.1.2-Food Ingestion Doses Collective population doses from food ingestion are calculated on the basis of the region's agricultural productivity rather than its population.
This is because the total population dose from food pathways is proportional to the total amounts of radionuclides in all food produced in the region rather than the number of people exposed.
The model employed by the NRC 22
BMFT staff considers population doses resulting fr.om radioactive contamination of vegetable, meat, and milk products produced in the region.
For population dose calculations, the vegetable category includes fruit and grain crops as well. The procedure followed by the staff to compute food ingestion doses is similar to that used for inhalation and external doses and is composed of the fcilowing procedural steps:
a.
The site region is divided into segments and each segment is assigned a productivity rate for reach food category (vegetables, 2
meat, and milk, in kg/yr per km );
b.*
The average activity concentrations for each food type are computed and multiplied by thL segment productivity factor and by the segment area; c.
Total activity content of the regional food production is then determined by summing over the segments;.and d.
Population doses are determined assuming that all food produced in the region is consumed by a population with the same age distri-bution as the U.S. population.
Agricultural productivity data required for use in this analysis are generally available on a county-by-county basis for a relatively recent year.
The available raw data should be projected forward in time to provide a reason-able estimate of productivity during the final year of mill operation.
If other means are not available, the NRC staff considers it acceptable to assume that regional agricultural productivity will remain in constant proportion to the U.S. population.
Should other site-specific data not be available, the staff will rely on the statewide average productivity data presented in Table 7.
The following equation is used to obtain segment average radio -
nuclide concentrations in vegetables:
I (19) vis "V9) " [ w C C
vs vis v
~
where
~
C is the average concentration of radionuclide i in vegetable vis type v produced in segment s, in pCi/kg; Cyg,(avg) is the average concentration of radionuclide i, averaged over all types of vegetables, in segment s, in pCi/kg; and 23
ab BMF(
W is the weighting factof for vegetable type v in segment s vs (fraction of total production), dimensionless.
When relying on the state-average production data given in Table 7, the NRC staff will use values of W, that have been selected to roughly correspond to the fractions of the three vegetable types in the average diet.
From Reference 1, these W values are 0.78 for above ground vegetables, 0.20 for y
potatoes, and 0.02 for other below ground vegetables.
The gross activity content of the regional food production for each food type (vegetables, meat, or milk) is obtained by o' eu Ofi * {O AC (20) fs 3 fis s
where 2
A, is the area of segment s, in km ;
C is the concentration of radionuclide i in food category f in fis segment s, in pCi/kg; G
is the productivity factor for food f in segment s, in kg/yr fs 2
per km ; and Qj is the gross activity content of radionuclide i in food f, f
in pCi/yr.
Since the food produced may be eaten at different rates by different age groups and since ingestion dose conversion factors are also age dependent, it is necessary to establish the fractions of the Q g values determined by f
Equation 20 that are ingested by the various age groups.
The following rela-tionship applies:
F U h
(21) pk fk Ffk =
{Fpk fk U
k
~
where F
is the fraction of the production of food type f ingested by fk individuals in age group k, dimensionless; F
is the fraction of the regional population belonging to age pk group k, dimensionless; and 24
asi
?
o (Mwe{c U
is the average consumption rate in kg/yr or L/yr of food type f fk for an individual in age group k (see Table 8 for values).
In the absence of suitable site-specific information, the NRC staff will assume average consumption rates for the population at large, as given in Table 8, and population age fractions and fractional consumption rates, as given in Table 9.
Using values obtained from Equations 20 and 21, total population inges-tion doses from all food categories are calculated by M (ing) = 10 8 E Q j fkDCFijk(ing)
?
(22)
F j
ff fik where E
is a factor to account for activity remaining after food prepara-f tion, dimensionless; and M (ing) is the resulting regional population dose f roin food inge:; tion j
for organ j, in rem /yr.
The value of E is assumed to be 0.5 for vegetables and 1.0 for meat f
and milk.
Fractions of the population belonging to the various age groups used in Equation 20 are determined from U.S. census data in the absence of site-specific information (see Table 9 for values).
3.2 Continental Population Doses 1
Substantial contributions to the total population dose may arise from 222Rn across the North American continent.
Forma-l the transport of released tion of long-lived 21 Pb from 222Rn may result in both inhalation and ingestion doses to people in Canada and Mexico, as well as in the United States (Ref. 8).
I In order to estimate population doses occurring beyond the immediate region of the site, the staff makes use of the data presented in Table 10. These j
data consist of estimates of population doses resulting from 1,000-Ci releases 1
The l
of 222Rn from four specific locations in the western United States.
location closest to the mill site should be used. The population doses pro-vided are those that would have resulted from releases during calendar year l
1978, including doses to Canadian and Mexican populations, and are based on the use of the environmental dose commitment concept with an integrating period of 100 years.
25 i
.ao.
W For projected releases of 222Rn in future years, resulting population doses are computed by assuming those doses to be proportional to the U.S.
population (use the population data provided in Table 11).
The anticipated annual 222Rn release, in kCi, is multiplied by the appropriate population doses from Table 10, and these results are then multiplied by the ratio of the projected U.S. population for the year of release to the 1918 U.S.
population.
3.3 Total Population Dose Commitments Population doses over the site region and the North American continent are computed on an annual basis for the milling, pile drying, and postreclama-tion uranium mill life-cycle phases.
The total radiological impact due to emissions during the first two phases is estimated by multiplying the annual impacts by the durations and summing.
Total annual impacts for each of the three phases are obtained by j = M (inh + ext) + M (ing) + M (Rn)
(23)
M j
j j
where M
is the annual committed population dose to organ j, in rem /yr; j
and i
M (Rn) is the annual continental population dose from 222Rn and its j
daughters to organ j, in rem /yr.
Total impacts over the first two mill-life-cycle phases are obtained by M (m&d) = T,M (m) + T M (d)
(24) j j
dj where i
M (d) is the annual committed population dose to organ j during j
l the drying phase, in rem /yr; M(m) is the annual committed population dose to organ j during j
the milling phase, in rem /yr; M (m&d) is the aggregate committed population dose to organ j over j
l the milling and drying phases, in rem; and T,T are the durations of the operational and pile drying phases, g d respectively, in yr.
26
.. d.
. se QU The calculation, compilation, and presentation of these population doses is considered by the NRC staff to represent a reasonably complete description of the radiological impact incurred by the operation of a +.ypical uranium mill.
D.
IMPLEMENTATION Portions of the models specified in this guide have been used by the NRC staff in evaluating current uranium mill licensing applications.
Except in those cases in which an applicant proposes acceptable alternative methods foi performing the evaluations described herein, the methods described in this guide are to be used for radiological impact evaluations for uranium mill license applications or renewals docketed after December 1, 1980.
e 27
d
}
n+.
Bd I
3 TABLE 1 ISOTOPES AND PARTICLE SIZES FOR WHICH DIRECT AIR CONCENTRATIONS (C VALUES) ARE REQUIRED AS INPUT' DATA adip Particle Size Group Characteristics (Ref. 1) i Unit Density Activity-Median Aerodynamic Equivalent Particle Diameter Mean
- Density, Diameter (AMAD),
Deposition size Group
- Range, um Diameter, um g/cm3 pm Velocity, m/sec 1.0 8.9 3.0 1.0 x 10.2
~
p=1 1.0 2.4 1.5 1.0 x 10 7 p=2 p=3 1 to 10 5.0 2.4 7.75 1.0 x 10 -2 p=4 10 to 80 35.0 2.4 54 8.82 x 102 0.3 1.0 0.3 0.3 x 10 p=5 Particle Size Group Index**
i Radionuclide p=1 p=2 p=3 p=4 p=5 1
uranium-238 C&R C&R C&R C&R 2
thorium-234 se se se se 3
protactinium-234 se se se se 4
uranium-234 se se se se 5
thorium-230 C&R C&R C&R C&R 6
radium-226 C&R C&R C&R C&R 7
radon-222***
se se se se 8
polonium-218 se se se se C&R 9
lead-214 se se se se C&R 10 bismuth-214 se se se se C&R 11 polonium-214 se se se se se 12 lead-210 C&R C&R C&R C&R C&R 13 bismuth-210 se se se se C&R 14 polonium-210 se se se se C&R AParticle size groups are assigned to effluents as follows:
p=1forgellowcake 22 Rn air in-dust; p = 2, 3, or 4 for fugitive ore and tailings dusts, p = 5 for growth concentrations of particulate daughters.
enThe entry "C & R" indicates that the particular C value is explicitly calculated adip by the staff and required as input for use of the models, equations, and data described in this guide.
The entry "se" indicates that radionuclide is assumed to be in secular, equilibrium with the next-higher-up parent for which the direct air concentration is explicitly calculated.
The air concentration of 222Rn is also calculated by the staff and is required as input for use of this guide; 222Rn gas is not assigned a particle size.
28
\\
A-DRIR TABLE 2 ENVIRONMENTAL TRANSFERS COEFFICIENTS
- U Th Ra Pb I. Plant / Soil (Byj)
(pCi/kg plartt - wet weight)/(pCi/kg soil - dry weight)
-3
-3
-2
-3 a.
Edible Above Ground 2.5 x 10 4.2 x 10 1.4 x 10 4.0 x 10
-3
-3
-3
-3 b.
Potatoes 2.5 x 10 4.2 x 10 3.0 x 10 4.0 x 10
-3
-3
-2
-3 c.
Other Below Ground 2.5 x 10 4.2 x 10 1.4 x 10 4.0 x 10
-3
-3
-2
-2 d.
Pasture Grass 2.5 x 10 4.2 x 10 1.8 x 10 2.8 x 10 e.
Stored Feed (Hay) 2.5 x 1073
-3
-2
-2 4.2 x 10 8.2 x 10 3.6 x 10 II. Beef / Feed (Fbi)
-4
~4
-4
-4 (pCi/kg per pCi/ day) 3.4 x 10 2.0 x 10 5.1 x 10 7.1 x 10 III. Milk / Feed (F,5)
~4
-6
-4
-4 (pCi/L per pCi/ day) 6.1 x 10 5.0 x 10 5.9 x 10 1.2 x 10 Ssurces for tnese data include References 9-12.
29
TABLE 3 INHALATION 00!!E CONVERSION FACTORS mrem /yr per pCi/m3 Radon Decay Products Particle Size = 0.3 micron 21oPb 21opo 3
Density = 1.0 g/cm AMAD = 1.0 microns Whole Body 7.46E+00 1.29E+00 Bone 2.32E+02* 5.24E+00 Kidney 1.93E+02 3.87E+01 Liver 5.91E+01 1.15E+01 Mass Average Lung 6.27E+01 2.66E+02 Yellowcake dust Particle Size = 1.0 micron assU 234U 2soTh 22sRa stoPb 21opo 3
Density = 8.9 g/cm AMAD = 3 microns Whole Body 9.82E+00 1.12E+01 1.37E+02 3.58E+01 4.66E+00 5.95E-01 Bone 1.66E+02 1.81E+02 4.90E+03 3.58E+02 1.45E+02 2.43E+00 Kidney 3.78E+01 4.30E+01 1.37E+03 1.26E+00 1.21E+02 1.79E+01 Liver 0.0 0.0 2.82E+02 4.47E-02 3.69E+01 5.34E+00 Mass Average Lung 1.07E+3 1.21E+3 2.37E+03 4.88E+03 5.69E+02 3.13E+02 Uranium Ore dust Particle Size = 1.0 micron 23s0 234U 2soTh 22sRa 21oPb 220Po 3
Density = 2.4 g/cm AMAD = 1.5 microns Whole Body 4.32E+00 4.92E+00 1.66E+02 3.09E+01 4.36E+00 4.71E-01 Bone 7.92E+01 7.95E+01 5.95E+03 3.09E+02 1.35E+02 1.92E+00 Kidney 1.66E+01 1.89E+01 1.67E+03 1.09E+00 1.13E+02 1.42E+01 Liver 0.0 0.0 3.43E+02 3.87E-02 3.45E+01 4.22E+00 Mass Average Lung 1.58E+02 1.80E+02 3.22E+03 6.61E+03 7.72E+02 4.20E+02 Fine Tailings Particulates Particle Size = 5.0 microns 2ssU 234U 2soTh 22sRa 21opd stopo 3
Density = 2.4 g/cm AMAD = 7.75 microns Whole Body 1.16E+00 1.32E+00 1.01E+02 4.00E+01 4.84E+00 7.10E-01 Bone 1.96E+01 2.14E+01 3.60E+03 4.00E+02 1.50E+02 2.89E+00 }
Kidney 4.47E+00 5.10E+00 1.00E+03 1.41E+00 1.25E+02 2.13E+01 j i
Liver 0.0 0.0 2.07E+02 4.97E-02 ~ 3.83E+01 6.36E+00 e I
Mass Average Lung 1.24E+03 1.42E+03 1.38E+03 2.84E+03 3.30E+02 1.88E+02 Coarse Tailings Particulates Particle Size = 35.0 microns assy as4U 2soTh 22sRa 21oPb stopo s
Density = 2.4 g/ca 1
AMAD = 54 microns 3
7.23E-01 Whole Body 7.92E-01 9.02E-01 5.77E+01 4.90E+01 4.43E+00
'?
Bone 1.34E+01 1.46E+01 2.07E+03 3.90E+02 1.38E+02 2.96E+00 Kidney 3.05E+00 3.47E+00 5.73E+02 1.38E+00 1.15E+02 2.19E+01 J
Liver 0.0 0.0 1.19E+02 4.85E-02 3.51E+01 6.52E+00
ARead 2.32E+02 as 2.32 x 102 = 232.
k 1
b e
/
f 30 1
i i
l l
l l
l
s.
4 DR
'IABLE 4 DOSE C0K _ -.aN FACTORS FOR EXTERNAL EXPOSURE Dose Factors for External Doses from Air concentrations (mrem /yr per pCi/m3)
Radionuclide Skin Whole Body
- 2380 1.05E-05**
1.57E-06 234Th 6.63E-05 5.24E-05 234mPa 8.57E-05 6.64E-05 234U 1.36E 05 2.49E-06 2soTh 1.29E-09 3.59E-06 226Ra 6.00E-05 4.90E-05 222Rn 3.46E-10 2.83E-06 21spo 8.18E-07 6.34E-07 214Pb 2.06E-03 1.67E-03 214Bi 1.36E-02 1.16E-02 214Po 9.89E-07 7.66E-07 21 Pb 4.17E-05 1.43E-05 Dose Factors for External Ocses from Ground Concentrations (mrem /yr per pCi/m2)
Radionuclide Skin Whole Body
- 23sU 2.13E-06 3.17E-07 l
234Th 2.10E-06 1.66E-06 l
234mPa 1.60E-06 1.24E-06 l
234U 2.60E-06 4.78E-07 2soTh 2.20E-06 6.12E-07 226Ra 1.16E-06 9.47E-07 222Rn 6.15E-08 5.03E-08 218Po 1.42E-08 1.10E-08 214Pb 3.89E-05 3.16E-05 l
214Bi 2.18E-04 1.85E-04 214Po 1.72E-08 1.33E-08 21oPb 6.65E-06 2.27E-06 Doses to internal body organs are assumed to be the same as computed for
~
l the whole body.
l Read as 1.05 x 10 5 or 0.0000105.
l l
31
w.
haali btIl TABLE 5 FOOD CONSUMPTION RATES USED FOR CALCULATING DOSES TO INDIVIDUAL 5 Ingestion Rates by Age Group *
(kg/yr)
Infant Child Teen Adult I. Vegetables (Total) 47.8 76.1 105.
- a. ' Edible Above Ground 17.3 28.9 39.9 27.2 42.2 60.4 b.
Potatoes 3.3 5.0 5.0 c.
Other Below Ground II. Meat (Beef, Fresh Pork, 27.6 44.8 78.3 and Lamb)
III. Milk (L/yr) 208.
208.
246.
130.
'All data are taken from Reference 5 Ingestion rates are averages for typical farm households.
No allowance is routinely credited for portions of year when locally grown or home grown food may not be available.
32
TABLE 6 INGESTION DOSE CONVERSION FACTORS Internal 00se Conversion Factors by Organ and' Age Qrem per pCi ingested)
Age Group Organ 238U 234U 234Th 230Th 22sRa*
21oPb 2toBi 210po Infant Wh. Bod 3.33E-04 3.80E-04 2.00E-08 1.06E-04 1.07E-02 2.38E-03 3.58E-07 7.41E-04 Bone 4.47E-03 4.88E-03 6.92E-07 3.80E-03 9.44E-02 5.28E-02 4.16E-06 3.10E-03 Liver 0.
O.
3.77E-08 1.90E-04 4.76E-05 1.42E-02 2.68E-05 5.93E-03 Kidney 9.28E-04 1.06E-03 1.39E-07 9.12E-04 8.71E-04 4.33E-02 2.08E-04 1.26E-02 Child Wh. Bod 1.94E-04 2.21E-04 9.88E-09 9.91E-05 9.87E-03 2.09E-03 1.69E-07 3.67E-04 Bone 3.27E-03 3.57E-03 3.42E-07 3.55E-03 8.76E-02 4.75E-02 1.97E-06 1.52E-03 Liver 0.
O.
1.51E-08 1.78E-04 1.84E-05 1.22E-02 1.02E-05 2.43E-03 Kidney 5.24E-04 5.98E-04 8.02E-08 8.67E-04 4.88E-04 3.67E-02 1.15E-04 7.56E-03 Teenager Wh. Bod 6.49E-05 7.39E-05 3.31E-09 6.00E-05 5.00E-03 7.01E-04 5.66E-08 1.23E-04 Bone 1.09E-03 1.19E-03 1.14E-07 2.16E-03 4.09E-02 1.81E-02 6.59E-07 5.09E-04 Liver 0.
O.
6.68E-09 1.23E-04 8.13E-06 5.44E-03 4.51E-06 1.07E-03 Kidney 2.50E-04 2.85E-04 3.81E-08 5.99E-04 2.32E-04 1.72E-02 5.48E-05 3.60E-03 Adult Wh. Bod 4.54E-05 5.17E-05 2.13E-09 5.70E-05 4.60E-03 5.44E-04 3.96E-08 8.59E-05 Bone 7.67E-04 8.36E-04 8.01E-08 2.06E-03 4.60E-02 1.53E-02 4.61E-07 3.56E-04 Liver 0.
O.
4.71E-09 1.17E-04 5.74E-06 4.37d-03 3.18E-06 7.56E-04 Kidney 1.75E-04 1.99E-04 2.67E-08 5.65E-04 1.63E-04 1.23E-02 3.83E-05 2.52E-03
" Adult whole body and bone dose conversion factors for 22sRa have been obtained from Reference 5 and are based on applicable models and data from Reference 13.
22sRa whole body and bone dose conversion factors for other age groups have been computed by assuming the same proportion to adult whole body and bone dose factors as given in~ Reference 14.
All other dose conversion factors are directly from Reference 14.
- e 3==
~'".!
am DRLF TABLE 7 AVERAGE AGRICULTURAL PRODUCTIVITY FACTORS FOR VARIOUS STATES State-Average Productivity *
(kg/yr per km )
z State Vegetables Meat Milk Arizona 580 1,040 1,130 Colorado 2,800 3,200 1,400 Idaho 14,200 2,000 3,400 Montana 1,800 2,000 370 Nevada 18 510 230 New Mexico 280 1,150 460 South Dakota 2,400 6,400 3,600 Texas 1,200 5,300 2,100 Utah 370 790 1,800 Washington 10,700 1,600 6,000 Wyoming 320 1,400 230
' Data presented are based on a staff survey and analysis of available data on agricultural productivity for 1973.
l I
l l
34
=-
i.nc.-
Exh.
DRVif TABLE 8 FOOD CONSUMPTION RATES USED FOR CALCULATING DOSES TO POPULATIONS Average Consumpticn Rates *
(kg/yr)
Food Category Infants Children Teens Adults I. Vegetable Pathway A.
Berries and Tree Fruit O.
54.1 63.9 49.2 B.. Fresh Vegetables **
1.
Potatoes 0.
27.2 42.3 60.4 2.
Other root veg.
O.
3.4 5.0 5.0 3.
Leafy vegetables 0.
5.8 9.4 13.9 4.
Other above ground vegetables 0.
11.4 19.5 26.0 C.
Processed Vegetables 1.
Potatoes 0.
2.3 3.6 5.2 2.
Other root veg.
O.
0.9 1.4 1.4 3.
Leafy vegetables 0.
0.4 0.6 0.8 4.
Other above ground vegetables 0.
14.4 24.6 32.8 D.
Grain, Rice, and Wheat 0.
118.2 136.2 90.8 Total Vegetables 0.
238.1 306.5 285.5 II. Heat, Pathway A.
Beef and Lamb **
0.
21.8 35.9 64.0 B.
Unprocessed Pork **
0.
5.9 8.9 14.3 C.
Poultry and Processed Pork 0.
21.0 33.2 49.6 Total Meat 0.
48.7 78.0 127.9 III. Milk Pathway (L/yr)
A.
Fresh Milk **
207.6 207.6 246.0 129.6 B.
Milk Products 0.
27.2 45.4 46.7 Total Milk 207.6 234.8 291.4 176.3 AAll data are taken from Reference 5 and are representative of average consumption rates by individuals at farm residences.
nsThese food categories are evaluated for individual doses from ingestion pathways.
35
4 $E s DR\\fi TABLE 9 AGE DISTRIBUTION OF POPULATION, AVERAGE AND PER CAPITA CONSUMPTION RATES, AND FRACTIONS USED IN THE ABSENCE OF SITE-SPECIFIC DATA Average Total Consumption Rates **
Age Fraction of (kg/yr)
Group Population
- Vegetables Meat Milk Infants 0.0179 0.
O.
207.6 Children 0.1647 238.1 48.7 234.8 Teenager's 0.1957 306.5 78.0 291.4 Adults 0.6217 285.5 127.9 176.3 Fraction of Regional Production Ingested by Each Age Group Age Group Vegetables Meat Milk Infants 0.
O.
0.0178 Children 0.1418 0.0780 0.1850 Teenagers 0.2167 0.1485 0.2728 Adults 0.6415 0.7735 0.5244 AAge fractions given reflect average values for the entire U.S. population indicated by 1970 census data, as reported in Reference 15.
- Consumption rates given are from Table 8 and are not those used for, or appropriate to, the calculation of maximum individual doses.
36
^~:
m BRM TABLE 10 CONTINENTAL POPULATION DOSES PER kCi 0F 222RN RELEASED IN 1978 Population Doses Resulting from a 1-kCi Release of 222Rn During 1978, organ-rem
- Bronchial Whole Pulmonary.
Release Site Epithelium Body Lun L Bone Casper, Wyoming 56.
8.8 2.0 120.
Falls City, Texas 72.
5.8 1.6 77.
Grants','New Mexico 52.
8.2 1.8 110.
Wellpinit, Washington 43.
9.0 1.7 120.
Average 56.
8.0 1.8 110.
RValues given are based on data reported in Reference 8 and amended for inclusion in Reference 1.
Exposure pathways considered include inhalation and ingestion.
Isotopes considered include 222Rn and its short-lived daughters, 21oPb, 21 obi, and 21oPo.
A 100 year integrating period was used in the application of the environmental dose commitment concept.
e 37
KE.*
!1 RUT TABLE 11 PROJECTED POPULATION OF THE UNITED STATES, 1978-2100 Projected U.S.
Projected U.S.
Population, Population, Year mi.11 ions
- Year millions
- 1978 218.4 1992 247.4 1979 220.2 1993 249.3 1980 222.2 1994 251.1 1981 224.2 1995 252.8 1982 226.3 1996 254.4 1983 228.5 1997 255.9 1984 230.7 1998 257.5 1985 232.9 1999 258.9 1986 235.1 2000 260.4 1987 237.2 2025 287.5 1988 239.4 2050 291.1 1989 241.5 2075 291.9 1990 243.5 2100 293.0 1991 245.5 Population projections through the year 2000 are from Reference 16.
Later projections were obtained from Reference 8 and are based on a predicted growth rate obtained from Reference 17.
38
b e<,
/
/
N RESUSPENDED AIR DIRECT AIR CONCENTRATION CONCENTRATIONS pC&m' PCkm' (C4'st
- al (Cadw
, r n
\\
[
h USED TO COMPUTE INHALATION DOSE i
AND EXTERNAL OOSES FROM TOTAL AIR SUBMERSION IN A CONTAMINATED DIRECT CONCENTRATIONS DEPOSmON pCUm ATMOSPHERE a
a pCkm -sec ICg's)
(D 's!
g
\\
/
4 Nr
/
3 x
3 TOTAL OROUND DEPOSITION CONCENTRATIONS pCum'~sec pCWm' 1D 's) g (C,g'el
\\
USEC TO COMPUrE EXTERN AL DOSES
\\
Fh0M CCNTAMINATED GROUND PLANE m
l CONCENTRATIONS USED TO COMPUTE VEGETA8LE VEGETATION INGESTION DOSES pCWg (C 'el g
1 1
e
% CONCENTRATIONS
~
USED TO COMPUTE MEAT (BEEF)
MEAT INGESTION DOSES pCUkg (C 's) g 4
/
p MILK USED TO COMPUTE MILK
+
CONCENTRATIONS INGESTION DOSES
~
pCL1 (C,, s)
Diagram Of Information FIOw and Use FOr Dose Calculation d
Figure 1.
Schematic
- 417~Sp A
- - ~. _ _ _ _ _
.O d.
bD TABLE 12 CONVERSION FACTORS INTO SI UNITS CONVERSION IN OLD IN HEW FACTOR FROM UNITS
- SI UNITS OLD TO NEW UNITS Activity Concentrations (Environmental)
Airborne Particulates and Gas pCi'm 3 Bq m 8 3.70E-02 Liquids.(Water, Milk, etc.)
pCi'L 1 Bq' L 1 3.70E-02 Solids (Soil, Sediment, pCi kg 1 Bq*kg 1 3.70E-02 Vegetation, Food Stuff, etc.)
Activity Concentrations (Effluent)
Gas (air)
(pCi'mL 1)**
Bq'm 3 3.70E+10 Liquid (pCi'mL 1)**
Bq'L 1 3.70E+07 Exposure Rate (Environmental) pR'h 1 C'kg 1*h 1 2.58E-10 Absorbed Dose mrad Gy 1.00E-05 Dose Equivalent mrem (Sv)***
1.00E-05 Dose Equitalent Rate mrem'yr 1 (Sv yr 1)***
1.00E-05 (Commitment)
- Sanctioned for temporary use.
- Adopted because of established convention and use in Maximum Permis-sible Concentration (MPC) tabulations.
- Proposed, not yet authorized for use.
40
as.
a.i.
REFERENCES 1.
" Final Generic Environmental Impact Statement on Uranium Milling," USNRC Report NUREG-0706, Office of Nuclear Materials Safety and Safeguards, September 1980.
2.
M. H. Momeni, Y. Yuan, and A. J. Zielen, "The Uranium Dispersion and Dosimetry (UDAD) Code," US NRC Report NUREG/CR-0553.
3.
" Environmental Radiation Dose Commitment:
An Application to the Nuclear Power Industry," Environmental Protection Agency, EPA-520/4-73-002, 1974.
4.
D. C. Kocher, " Nuclear Decay Data for Radionuclides Occurring in Routine Releases from Nuclear Fuel Cycle Facilities," USNRC Report ORNL/NUREG/
TM-102, August 1977.
5.
J. F. Fletcher and W. L. Detson (compilers), " HERMES - A Digital Computer Code for Estimating Regional Radiological Effects from the Nuclear Power Industry," Hanford Engineering Development Laboratory, HEDL-TME-71-168, December 1971.
6.
ICRP Task Group on Lung Dynamics, " Deposition and Retention Models for Internal Dosimetry of the Human Respiratory Tract," Health Physics 12:181, 1966.
l 7.
National Academy of Sciences--National Research Council, "The Effects
(
on Populations of Exposure to Low Levels of Ionizing P.adiation," Report of the Advisory Committee on the Biological Effects of Ionizing Radiation i
(BEIR), U.S. Government Printing Office, 1972.
8.
C. C. Travis et al., "A Radiological Assessment of Radon-222 Released from Uranium Mills and Otner Natural and Technologically Enhanced Sources,"
Oak Ridge National Laboratory Report ORNL/NUREG-55, USNRC Report NUREG/
CR-0573, 1979.
41
.a,
- a..;.1 :
REFERENCES (Continued) 9.
Y.' C. Ng et al., " Prediction of the Maximum Dosage to Man from the Fallout of Nuclear Devices, Handbook for Estimating the Maximum Internal Dose from Radionuclides Released to the Biosphere," USAEC Report UCRL-50163, Part IV, 1968.
10.
R. S. Booth et al., "A Systems Analysis Methodology for Predicting Dose to Man from a Radioactivity Contaminated Terrestrial Environment,"
Proceedings of the Third National Symposium on Radioecology, USAEC Report CONF-710501, Oak Ridge, Tenn., pp. 877-893, 1971.
11.
R. J. Garner, " Transfer of radioactive Materials from the Terrestrial Environment to Animals and Man," CRC Press, Cleveland, Ohio, 1972.
12.
L. L. McDowell-Boyer et al., " Review and Re::ommendations of Dose Conver-sion Factors and Environmental Tranport Parameters for 21oPb and 22sRa,"
Oak Ridge National Laboratory Report ORNL/NUREG-56, USNRC Report NUREG/
CR-0574, 1979.
13.
International Commission on Radiological Protection, " Recommendations of the International Commission on Radiological Protection," ICRP Publication 10A, Pergamon Press, New York, 1971.
14.
G. R. Hoenes and J. K. Soldat, " Age-Specific Radiation Dose Commitment Factors for a One-Year Chronic Intake," Battelle Pacific Northwest Laboratories, USNRC Report NUREG-0172, November 1977.
15.
" Environmental Analysis of the Uranium Fuel Cycle, Part II - Nuclear Power Reactors," U.S. Environmental Protection Agency, EPA-520/
9-73.003-C, November 1973.
42
p.s,.
^
u E-A REFERENCES (Continued) 16.
U.S. Bureau of the Census, " Projections of the Population of the United States:
1977-2050," Current Population Reports Series P-25, No. 704, U.S. Government Printing Office, Washington, D.C. 20402, 1977.
17.
" Development of the Methodology Relevant to U.N. Global Projections,"
paper presented to the Ad Hoc Group of Experts on Demographic Projec-tion, U.N. Fund for Public Activities, Population Division, New York, 7-n November 1977.
18.
D. L. Strenge and T. J. Bander, "MILDOS--A Computer Program for Calcu-lating Environmental Radiation Doses from Uranium Recevery Operations,"
U.S. NRC Report NUREG/CR-2011 (PNL-3767), April 1981.
19.
D. R. Kalkwarf, " Solubility Classification of Airborne Products from Uranium Ores and Tailings Piles," U.S. NRC Report NUREG/CR-0530, January 1979.
43
TN! '.
w t
LIST OF SYMBOLS Symbol Description a
Equal to (t - 1.82) if t > 1.82 and otherwise equal to zero, in yr 2
A Area of segment s, in km s
B Soil-to plant transfer coefficient for radionuclide i, yg vegetation type v, (pCi/kg (wet) plant per pCi/kg (dry) soil)
C Direct air concentration of radionuclide i, particle adip 3
size p, resulting from operational releases, in pCi/m 3
C,9 Total air concentration of radionuclide i, in pCi/m C,$p(t)
Total air concentration of radionuclide i, particle size 3
p, at time t, in pCi/m Carip(t)
Resuspended air concentration of radionuclide i, particle 3
size p, at time t, in pCi/m arip(T )
Residual resuspended air concentration of radionuclide C
d i in particle size p resulting from resuspnsion of mate-rial released during operation which contributes to the air concentration at the end of the T year drying period, d
3 in pCi/m C
Resulting average concentration of radionuclide i in bi
~
meat, in pCi/kg C
Concentration of radionuclide i in food category f in fis segment s, in pCi/kg (wet weight) 44
..a,.
..aaE.
04n LIST OF SYMBOLS (Continued)
Cgg(t)
Ground surface concentration of radionuclide i at time t, in pCi/m2 g (T )
Residual ground concentration of radionuclide i resulting C
g d
from material released during operation which is present 2
at the end of the T year drying period, in pCi/m g
g (T,)
Ground concentration of radionuclide i at the time of C
g 2
mill shutdown, in pCi/m C yp(Pb +- Ra)
Incremental 21oPb ground concentration resulting from g
22sRa deposition, in pCi/m2 C
Concentration of radionuclide i in hay (or other stored hi feed), in pCi/kg (wet weight)
C,9 Resulting concentration of radionuclide i in milk, in pCi/L C
Concentration of radionuclide i in pasture grass, in pgg pCi/kg (wet weight)
C Resulting concentration of radionuclide i, in vegetation yg l
v, in pCi/kg (wet weight) l l
C Average concentration of radionuclide i in vegetable vis type v produced in segment s, in pCi/kg (wet weight) l Cygg(avg)
Average concentration of radionuclide i, averaged ove.-
all types of vegetables, in segment s, in pCi/kg (wet weight) 45
a>
nu$s a
07 LIST OF SYMBOLS (';ontinued)
DCF )(cid)
Dose conversion factor for cloud exposure for radionuclide i, organ j, in arem/yr per pCi/m3 DCF$3(gnd)
Dose conversion factor for ground exposure for radionuclide i, organ j, in mrem /yr per pCi/m2 DCFijk(ing)
Ingestion dose conversion factor for radionuclide i, organ j, age group k, in mrem /pCi ingested DCF$3p(inh)
Inhalation dose conversion factor for radionuclide i, 3
organ j, and particle size p, in mrem /yr per pCi/m D
Resulting direct deposition rate of radionuclide i, in di pCi/m2 per sec D
Total deposition rate, including deposition of resuspended j
2 activity, of radionuclide i, in pCi/m per sec d)(ext)
External dose to organ j, in mrem /yr d (inh)
Inhalation dose to organ j, in mrem /yr j
djk(ing)
Ingestion dose for organ j, age group k, in mrem /yr jk(tot)
Total dose to organ j of an individual in age group k d
from all exposure pathways, in mrem /yr d,(ext)
Average external dose to organ j in segment s, in j
mrem /yr 46
Y:
o'.
0,S a
=
a a
LIST OF SYMBOLS (Continued) d),(inh)
Average inhalation dose to organ j in segment s, in mrem /yr E
Factor to account for activity remaining after food pre-f paration, dimensionless E
Fraction of the foliar deposition reaching edible portions y
of vegetation v, dimensionless F
Feed-to-meat transfer coefficient for radionuclide i, bi in pCi/kg per pCi/ day ingested (see Table 2)
F Fraction of the production of food type f ingested by fk individuals in age group k, dimensionless F,9 Feed-to-milk transfer coefficient for radionuclide i, in pCi/L per pCi/ day ingested (see Table 2)
Fractions of the total annual feed requirement assumed Fpg,Fh to be satisfied by pasture grass or locally grown stored feed (hay), respectively, dimensionless F
Fraction of the regional population belonging to age pk group k, dimensionless F
Fraction of the total deposition retained on plant r
surfaces, 0.2, dimensionless
-G Productivity factor for food f in segment s, in kg/yr fs 2
per km 47
~. a r
.i.
s k
LIST OF SYMBOLS (Continued) l Activity ingestion rate of radionuclide i by an individual ik in age group k, in pCi/yr M)
Annual committed population dose to organ j, in rem /yr M (d)
Annual committed population dose to organ j during the j
drying phase, in rem /yr M (ing)
Resulting regional population dose from food ingestion j
for organ j, in rem /yr M (inh + ext)
Resulting population dose from inhalation and external j
exposure pathways, in rem /yr M (m)
Annual committed population dose to organ j during the j
milling phase, in rem /yr M (m&d)
Aggregate committed population dose to organ j over the j
milling and drying phases, in rem M (Rii)
Annual continental population dose from 222Rn and its j
daughters to organ j, in rem /yr p
Assumed soil areal density for surface mixing, 240 kg(dry weight)/m2 P
Population residing in segment s s
Q Assumed feed ingestion rate, 50 kg(wet weight)/ day Qg Gross activity content of radionuclide i in food f, in f
pCi/yr 48 T
1
~
.f :
LIST OF SYMBOLS (Continued)
R (t)
Ratio of the resuspended air concentration to the ground p
concentration, for a ground concentration of age t yr,
~1 of particle size p, in m t
Time interval over which deposition has occurred, in sec T
Duration of time required to dry the tailings pile prior d
to reclamation, in yr T
Durations of the operational phase, in yr o
t Assumed duration of exposure while growing of vegetation y
v, in sec U
Average consumption rate of food type f for an individual fk in age group k (see Table 8 for values) in L/yr or kg/yr Milk (in L/yr) and meat (in kg/yr) ingestion rates for Umk,Ubk age group k U
Ingestion rate of vegetable category v for age group k, vk in kg/yr V
Deposition velocity of particle size p, in m/sec (see p
Table 1)
W Weighting factor for vegetable type v in segment s (frac-vs tion of total production), dimensionless 49
g Mi e
DRAFf LIST OF SYMBOLS (Continued)
Y, Assumed yield density of vegetation v, in kg/m2 (wet weight) 6(t)
Zero if t < 1.82 and unity otherwise, dimensionless A,
Assumed rate coastant for environmental loss, in sec 2 A
Radioactive decay constant for radionuclide i, in sec 1 A*
Effective removal constant for radionuclide i on soil, in yr 1 A*
Effective rate constant for loss by radioactive decay and migration of a ground-deposited radionuclide and d
equal to A + A,, in see 3
A Assumed decay constant of the resuspension factor R
(equivalent to a 50-day half-life), 5.06 yr 1 A,
Decay constant accounting for weathering losses (equivalent to a 14-day half-life), 5.73 x 10 7 sec 1 i
10 9 Terminal value of the resuspension factor for particles with a deposition velocity of 0.01 m/sec, in m
10 5 Initial value of the resuspension factor for particles with a deposition velocity of 0.01 m/sec, in m 1 10 3 Conversion factor for millirem to rem 0.01 Deposition velocity for the particle size for which the initial resuspension factor value is 10 5/m, in m/sec s
s 50
7m41 t
cr# h t
LIST OF SYMBOLS (Continued) 0.5 Fraction of vegetable activity remaining after food preparation, dimensionless 0.825 Effective reduction factor because of structural shielding for indoor exposure periods 1.82 Time required to reach the terminal resuspension factor, in yr 3.156 x 107 Sec/yr p
51
ui:
L 2:
.i I
APPENDIX A SITE-SPECIFIC INFORMATION AND DATA USED BY THE NRC STAFF IN PERFORMING RADIOLOGICAL IMPACT EVALUATIONS FOR URANIUM MILLING OPERATIONS Table A-1 lists and partially describes most of the information and data commonly used by the NRC staff in performing its uranium mill radi-ological impact evaluations.
All the data detailed in Table A-1 are not always available on a site-specific basis, in which case the staff will employ cpnservative estimates or assumptions.
In some situations, the data identified in Table A-1 may not be adequate, so the staff will attempt to secure additional information.
This situation may arise, for instance, when operations at more than one site are involved and the staff is required to evaluate combined impacts.
In most cases, however, provision of the data identified in Table A-1 allows the staff to completely fulfill its respon-sibilities with regard to the preparation of a thorough, knowledgeable, and technically sound radiological impact evaluation.
G 52 i
i.
3DM TABLE A-1 PLANT, PLANT OPERATIONS, METEOROLOGICAL, AND ENVIRONMENTAL DATA ROUTINELY USED BY THE NRC STAFF IN PERFORMING RADIOLOGICAL IMPACT EVALUATIONS I. PHYSICAL PLANT DATA A.
Detailed site plot plan (overlaid on topographic map, with scale and true north arrow) clearly identifying all locations of 1.
Site property boundaries 2.
Raw ore storage pads 3.
Primary crushers 4.
Secondary crushers 5.
Crushed ore storage areas 6.
Ore grinders 7.
Yellowcake dryer and yellowcake dryer stack
- 8.
Yellowcake packaging area and exhaust stack 9.
Tailings impoundments and their boundaries 10.
Any heap leach piles and their boundaries 11.
Restricted area boundaries if different from site property boundaries 12.
Fences B.
Plant operations data 1.
General data a.
Ore processing rates for all crushers and grinders, MT/d; hr/d and d/yr operational Raw ore grade, % U 0s by weight, average, and range b.
3 c.
Fractions of uranium, thorium, radium, and lead in raw ore expected to flow through to tailings d.
Expected yellowcake purity, % U 0s by weight, average, 3
and range, MT/yr produced e.
Expected calendar years of initial ore milling, final ore milling, and completion of tailings area reclamation aPart of the input to the NRC staff's impact assessment computer code consists of X, Y, and Z coordinates for various release and receptor locations.
The staff routinely determines these coordinates with respect to the topographic elevation at the location of the yellowcake dryer stack.
A list of all such locations should be given in the radiological assessment.
53
pu.
DRLFj Table A-1 (Continued) 2.
Ore storage data 2
a.
Areas of each pile or bin complex, in m b.
Ore storage masses 3 by weight c.
Ore grades, % U:,0 d.
Antidusting measures routinely implemented Anticipated dusting rates, in MT/yr e.
f.
Anticipated 222Rn releases, in Ci/yr g.
Fractions of input ore sent to storage 3.
Crushing, grinding data Description of ventilation air filtration equipment a.
b.
Design efficiency of exhaust filters c.
Minimum efficiencies of exhaust filters d.
Filter testing procedure and schedule if applicable Fraction of time filters not operational or used e.
f.
Any measured effluent concentrations g.
Stack heights and airflows h.
Anticipated release rates, in kg/hr or kg/MT yellowcake processed i.
Anticipated 222Rn release rate, in Ci/yr j.
Fractions of ore thrcughput reaching filters as dust 4.
Yellowcake drying and packaging data Processing rates, MT/hr, for drying and packaging if a.
different b.
Hr/d and d/yr drying and packaging operations are carried out Description of all ventilation air filtration equipment c.
with design, expected, and minimum efficiencies d.
Filtration equipment testing procedures and frequencies Any measured effluent concentrations e.
f.
Stack heights and airflows g.
Anticipated release rates, in kg/hr, for the dryer stack, the packaging area ventilation exhaust, and any yellowcake storage area ventilation exhausts
~
h.
Annual yellowcake yield, MT/yr 5.
Tailings impoundment system (including evaporation and/or settling ponds) data Complete physical, chemical, hydrological, and radio-a.
logical description 54
lssu-E,
- l %g,
ll
y }?
us; Table A-1 (Continued) 8)
III. ENVIRONMENTAL DATA A.
A detailed topographic map of the area within 8 km (5 mi) of the site showing the locations of all 1.
Site boundaries 2.
Lands owned, leased, or otherwise controlled (including mill site claims) by the applicant 3.
Lands privately owned 4.
Lands under the jurisdiction of the U.S. Bureau of Land Management 5.
Lands otherwise publicly held 6.
Lands useable and available for grazing 7.
Private residences or other structures used by the general public 8.
Vegetable or other crops, identified by type 9.
Private, public, and industrial water wells and natural springs 10.
Milk animals (cows or goats)
B.
Regional data (within 80 km) 1.
Population distributions by direction (16) and radius (for 1, 2, 3, 4, 5, 10, 20, 30, 40, 50, 60, 70, and 80 km) for a recent year (no earlier than 1970), for the last year of expected milling (approximate), and for the last year prior to completion of tailings area reclamation (approximate),
with expected age group fractions (if available) 2.
Available county food production data, in kg/yr, for vegetables (by type and totals), meat (all types), and milk; and any available future predictions by local governmental, industrial, or institutional organizations 56
m CA APPENDIX B STAFF METHODOLOGY FOR THE COMPUTATION OF 100-YEAR ENVIRONMENTAL DOSE COMMITMENTS A primary objective of the NRC staff's radiological impact analysis is to estimate the aggregate radiological impact of the evaluated facilities.
In attempting to achieve this goal, the staff employs the concept of environmental dose commitment (EDC) and uses an integrating period of 100 years.
In adopting this general calculational approach, the staff has also endeavored to select and employ a specific calculational scheme suitable for routine use, both by the NRC staff and uranium milling license applicants.
The specific technique used by the staff is, for this reason, greatly simplified but somewhat less comprehensive in comparison with other published approaches for EDC computa-tion.
This appendix describes the staff's technique for EDC evaluation and addresses the rationale for selecting a 100 yea'r integrating period.
j Ordinarily, to compute mar.imum individual doses, the staff uses environ-l mental concentrations calculated for the final year of the particular phase of milling operations.
The duration of the milling phase is most often esti-mated to be 15 to 20 years, while drying of tailings piles may require from 2 to 5 years or slightly longer.
The lengths of these time intervals define the value of the time variable "t" that appears in Equations 2, 3, 4, and 6 of regulatory position 1, Concentrations in Environmental Media, of this guide.
The staff technique for evaluating region'al population EDCs for an inte-grating period of 100 years following activity release involves artificially l
setting the value of t to 101 years.
The specific procedural steps taken by I
the staff in the calculation of 100 year EDCs are then as otherwise described in regulatory positions 1 and 3 and as follows:
1.
Obtain all necessary input direct air concentrations, as identified in Table 1, for average release rates (by isotope) over the time j
interval of the mill life-cycle phase being evaluated.
l 2.
Evaluate all required environmental media concentrations by means of the equations provided for this purpose in regulatory position 1, using a value of 101 years for the variable t appearing in Equations 2, 3, 4, and 6.
57 l
?
- /
a.1 3.
Based on the environmental media concentrations computed for t =
101 years, using appropriate population, agricultural, and other data as described in regulatory position 3, calculate the regional popula-tion doses for all exposure pathways for an exposure period of 1 year.
4.
Sum the computed doses, as appropriate, over all exposure pathways.
These calculational procedures actually result in the computation of the population dose commitments resulting from a 1 year exposure period to environmental concentrations existing during the 101st year of releases at the constant rates employed. The similarity of this result to the desired EDC (the. population dose commitments resulting from a 100 year period of exposure to environmental concentrations resulting from constant releases over a 1 year time period) is illustrated in Table B-1, which provides a comparison of staff and conventional methodologies for EDC computation.
This table has been organized to display the component parts of each calcu-lational method.
Line-by-line equivalence of these component parts can be readily demonstrated under conditions of constant population, population distribution, and agricultural productivity in the site region.
The staff has elected to use the approach described, rather than the more conventional approach, and a 100 year integrating period, primarily because of the following reasons:
1.
The major exposure pathways are dominated by doses resulting from airborne activity, which decreases rapidly in the absence of a continuing source (the resuspension factor has a half-life of about 50 days);
2.
The major dose impact of ground concentrations arises from the food ingestion pathways, which depend on estimates of agricultural productivity (forecast data for food productivity in specific areas are rare and are considered to be potentially unreliable);
3.
Inordinate computational difficulties are involved in routinely taking into account growth trends not amenable to description by very simple mathematical functions; and 4.
The vast majority of resulting population exposure results from environmental concentrations at distances between 20 and 80 km from the site at which routine atmospheric dispersion calculations cannot generally yield results with sufficient accuracy to justify accounting for minor perturbations.
58
[- 5 TABLE B-1 COMPARISON OF STAFF AND CONVENTIONAL TECHNIQUES FOR ENVIRONMENTAL DOSE COMMITMENTS CALCULATION NRC Staff EDC Calculational Technique
- Conventional EDC Calculational Technique Defined as:
Populatign dose commitments Defined as:
Population dose commitments rcsulting from a 1 year period of exposure resulting from a 100 year period of exposure to cnvironmental concentrations present to environmental concentrations resulting during the 101st year of constant releases.
from constant releases over a 1 year period.
Exposure Release Average Time Exposure Release Average Time Line Interval, yr Interval, yr Difference, yr Interval, yr Interval, yr Difference, yr 1
100 - 101 100 - 101 0
0-1 0-1 0
2 99 - 100 1
1-2 1
3 98 - 99 2
2-3 2
4 97 - 98 3
3-4 3
5 96 - 97 4
4-5 4
6 95 - 96 5
5-6 5
94 7-8 93 93 - 94 93 95 6-7 94 94 - 95 94 96 5-6 95 95 - 96 95 97 4-5 96 96 - 97 96 98 3-4 97 97 - 98 97 99 2-3 98 98 - 99 98 100 1-2 99 99 - 100 99 101 0-1 100 100 - 101 100 A
This table has been purposely organized to portray a line-by-line similarity between staff and conventional i
EDC computation methods.
Computation by both methods is broken down into component parts that, under con-ditions described in the text, can be shown to be mathematically identical.
Ds I
i s
I
n.
1 tu:a APPENDIX C RADON DOSE CONVERSION FACTOR The basis on which the NRC staff has relied for its radon daughter inhala-tion dose conversion factor consists of the following major component parts:
1.
The indoor working level (WL) concentration resulting from an outdoor 222Rn concentration of 1 pCi/m3 is approximately 5.0 x 10 8 WL.
2.
The number of cumulative working level months (WLM) exposure per year for an average individual at a constant concentration of one WL is 25 WLM/yr.
3.
The committed dose equivalent to the bronchial epithelium (basal cell nuclei of segmented bronchi) per unit WLM exposure is 5000 mrem (5 rem).
These component parts enter into the following equation, which yields the 222Rn inhalation dose conversion factor used by the staff:
5.0 x 10 8 WL
- 25 WLM/yr
- 5000 mrem -_ 0.625 mrem /yr 1 pCi/m3 WL WLM 1 pCi/m3 Each of the three components identified above derive from sources and data identified below:
1.
5 x 10 8 WL per pCi/m3 of 222Rn is established by the assumed indoor air concentration ratios for 222Rn, 21spo, 214Pb, and 21481 of 1.0/0.90/0.51/and 0.35.
These concentration ratios and the derived conversion factor are representative of conditions in a reasonably well-ventilated structure (Refs. 1 and 2).
2.
25 WLM/yr per WL concentration derives from the assumption that an average individual's average breathing rate will be about 50 percent of that of a working miner. A WLM is defined, in terms of exposure to a working miner, as one month's occupational exposure 60
~~~
~~ ~
..e.
85, j
to a 1-WL concentration.
This assumed breathing rate would result in an average individual receiving about 0.5 WLM as a result of the same length of exposure to air at a 1-WL concentration.
The following relationship applies:
(8760 hr/yr) x x 0.5 = 25 M/yr-WL 40 hr/ k 2 k/yr 3.
Five rem /WLM is the value derived from applying a quality factor (QF) of 10 for alpha radiation to convert from rad to tem (Refs.
1, 2, and 3) to the figure of 0.5 rad /WLM as reported in the BEIR Report (page 148 of Ref. 3).
The NRC staff considers the above basis for its 222Rn inhalation dose conversion factor to be both sound and reasonable, The staff acknowledges that radon dosimetry is extremely complex and strongly influenced by assumed environmental and biological conditions.
In view of the large variations induced by rather small changes in the assumed free-ion fraction, relative equilibrium, thickness of the intervening tissue and mucuous layers, etc.,
the staff has endeavored to use physical, environmental, and other data reasonably representative of average conditions.
REFERENCES FOR APPENDIX C 1.
" Potential Radiological Impact of Airborne Releases and Direct Gamma Radiation to Individuals Living Near Inactive Uranium Mill Tailings Piles," Environmental Protection Agency, EPA-520/1-76-001, January 1976.
2.
" Environmental Analysis of the Uranium Fuel Cycle, Part I--Fuel Supply,"
Environmental Protection Agency, EPA-520/9-73-003-B, October 1973.
3.
National Academy of Sciences--National Research Council, "The Effects on Populations of Exposure to Low Levels of Ionizing Radiation," Report of the Advisory Committee on the Biological Effects of Ionizing Radiations (BEIR), November 1972.
61
.: se a L$ VALUE/ IMPACT STATEMENT 1. PROPOSED ACTION 1.1 Description l The proposed action consists of the development and publication of a routine inethodology for assessing the radiological impacts of routine radio-active releases from uranium mills. These radiological impacts include doses to exposed individuals, doses to the population within an 80-km (50-mi) radius, doses to the entire U.S. population, and doses to the entire world population. Evaluations made using the published methodology would serve several regulatory and licensing purposes for which the methodology must be suitable. These purposes include evaluating compliance with 40 CFR Part 190 and NRC regulations, evaluating impacts of releases as part of the overall ALARA evaluation, and evaluation of environmental impacts to meet NEPA requirements. 1.2 Need for the Proposed Action Radiological impact evaluations for routine releases from uranium mills have been carried out in the past and numerous new and repeat evaluations will likely be required in the future. Past evaluations hhve been prepared in-house by NRC personnel or by personnel from national laboratories under contract. These assessments have lacked a uniformity of approach and purpose for numerous reasons, the most important being the absence of a standardized routine procedure. Other reasons include, but are not limited to, the evolu-tion of new models, techniques, and data; the development of new concerns requiring new methods of analysis; and the problems associated with having evaluations prepared by different groups of people. This situation needed to be corrected. The proposed action includes the publication of state-of-the-art analytical models, including environmental transport models and data, models and data for human dosimetry, and appropriate data for 62
s receptor characteristics. An example of the problems to be addressed by this effort is the evaluation of the long-term time-integrated impact of mill tailings piles, heretofore assessed by NRC only in terms of the impact during a single year. 1.3 Value/ Impact of the Proposed Actig 1.3.1 NRC The document conveying the results of the proposed action will be a useful tool and should result in substantial benefits to NRC. These include upgrading the quality of future evaluations, particularly with regard to uniformity, completeness, and the application of more up-to-date methods and data. Other benefits will include greater flexibility in personnel assignments and reduced allocations of personnel time to completing evaluations. 1.3.2 Other Government Agencies Other agencies will have available a reliable reference document explaining NRC's evaluation techniques. If evaluations can be conducted more uniformly, there will be a benefit to other agencies concerned with radiological and health impacts in that they may become more familiar with a routine approach and require less time to review NRC evaluations. l 1.3.3 Industrial and Public Interest Groups Clearly predictable impacts on these groups include the costs involved in familiarizing themselves with the product document. Benefits will be derived from more easily predicting and understanding the results of NRC evaluations. It is assumed that some differences from past evaluation tech-niques will be incorporated in the product document and that such changes l l would alter the results of past and future evaluations. The degree and effects of-such alterations are presently undefinable. 1.3.4 Public The public will derive a benefit from the availability of a reference document explaining NRC evaluation techniques and, hopefully, a further 63
..s. d$.. MAR benefit will be derived from the increase in quality of NRC evaluations and subsequent licensing decisions and regulatory requirenents. 2. TECHNICAL APPROACH The technical approach to be used is based in part on contract work pre-pared by staffs of the Argonne National Laboratory, Pacific Northwest Labora-tory and the Oak Ridge National Laboratory. This approach reflects techniques currently being adopted for use in review of uranium milling license applica-tions antf license renewal applications by the Office of Nuclear Material Safety and Safeguards. Comments on the technical approach were solicited by the issuance of the draft guide RH-802-4 for public comment. The comments received were evaluated and modifications were made to the Guide where appropriate. 3. PROCEDURAL APPROACH 3.1 Procedural Alternatives Possible SD procedures that may be used to carry out the proposed action include the following: j Regulation l Regulatory Guide ANSI Standard, endorsed by a Regulatory Guide Brinch Position Nbh2G 3.2 Value/ Impact of Precedural Alternatives Preparation of a NUREG report is inappropriate because the product docu-ment includes staff positions. An acceptable ANSI standard is neither avail-able nor currently under preparation. The subject matter of the product document is intended to convey informa-tional material as to the purposes,. mechanisms, and minimum requirements of NRC evaluations. It is also intended to demonstrate acceptable evaluation l 64
psi t i models for use by license applicants. Publication of a regulation is viewed as inappropriate because the strength of law is unnecessary and would not allow the flexibility often required in such matters wherein changing scien-tific, technical, and regulatory bases may be expected. Branch positions, although sometimes prepared for guidance of this sort, enjoy only limited distribution and are usually followed by a regulatory guide if they prove useful. In this case, no branch position has been pre-pared, nor is one expected. 3.3 Decision on Procedural Approach A regulatory guide should be prepared. 4. STATUTORY CONSIDERATIONS 4.1 NRC Authority The product document establishes routine procedures by which NRC will evaluate radiological impacts of routine airborne releases from uranium mills. These evaluations will be and are being used in "as low as is reasonably achiev-able" determinations to evaluate compliance with NRC regulations, to evaluate compliance with EPA's 40 CFR Part 190 regulation, and to evaluate environmental impacts as part of NRC's overall NEPA determination. 4.2 Need for NEPA Assessment The issuance of a guide on calculational models did not require an environmental impact statement as it was not "a major Commission action significantly affecting the quality of the environment" as detailed in para-graph 51.5(a)(10) of 10 CFR Part 51. 5. RELATIONSHIP TO OTHER EXISTING OR PROPOSED REGULATIONS OR POLICIES No potential conflicts with other agencies have been identified. How-ever, the product document will be a principal tool in the implementation 65
o ' N}t : BWi of 40 CFR Part 190, issued by EPA. Implementation of 40 CFR Part 190 is an NRC responsibility. There is some possibility that backfitting requirements may result from implementation of 40 CFR Part 190. Such possible requirements will not result from the proposed action, but rather from the original EPA regulation. 6.
SUMMARY
AND CONCLUSIONS The proposed action consists of developing and publishing final guidance on routine procedures for evaluating the radiological impact of routine air-borne releases of radioactive material from uranium mills. The recommended procedural approach is to publish the product document in the form of a final regulatory guide. I i l I l 66 -}}