United Nations Scientific Committee on the Effects of Atomic Radiation

ELECTRONIC ATTACHMENT 2

SUMMARY OF THE COMMITTEE'S PRE-2016
METHODOLOGIES AND THEIR DEVELOPMENTUNSCEAR 2016 Report, Annex A,
Methodology for estimating public exposures due to radioactive discharges

Contents
As part of the development of the 2016 methodology for estimating public exposures due toradioactive discharges, the Committee had requested a review of the main features of its
previous methodology and how this had been developed. The following tables contain asummary of different aspects of the Committee’s pre-2016 methodology (table 1), the dosequantities and integration times that had been used in previous assessments (table 2) and otherrelated information and assumptions that formed the basis of the Committee’s previous
approach to assessing radiation doses to the public from discharges of radionuclides to theenvironment.

Notes
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The United Nations takes no responsibility for the continued accuracy of that information or
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©

United Nations, May 2018. All rights reserved, worldwide.

This publication has not been formally edited.

Table 1. Key components of the Committee’s pre-2016 methodology
Factors

Previous approach
FEATURES OF THE SCENARIO
131

Discharges considered: noble gases, tritium,

I and particulates (representative composition assumed)Site description

Population distribution information representative of the situation in the early 1980s
GENERAL CONSIDERATIONS FOR DOSE ASSESSMENT

End points

Local, regional and global components of collective effective dose integrated to 100 years. Some presentation of per caput and representative individual doses

Atmosphericdispersion

Dispersion factors based on long-term sector-averaged Gaussian plume model. Long-term average dilution factors derived for downwind distances between 1 and
2,000 km based on representative values of deposition velocity and washout coefficient of 0.002 m/s and 0.0001 m/s, respectively; precipitation for 500 hours in a
year; 80% class D and 20% class C conditions, at average rate of 1.5 mm/h
Variation of concentrations of radionuclides in air with downwind distance beyond 1 km approximated to the following function in Committee’s assessments before
2000:
Ca (x) = D1 Q x-n
Best approximation was found for D1 of 5.3 × 10−7 s/m3 and for n of 1.42 [U7], assuming uniform wind rose

Aquatic dispersion

Factors based on total volume of freshwater bodies; marine dispersion assumed that North Sea exchange rates were representative of situation elsewhere. Residence
times based on information for 137Cs, 90Sr and 239Pu
Time-integrated concentration of radionuclide in water for discharge of activity A (Bq) assumed as follows: A/V (τ + λi) (Bq a/L), where V is volume of receiving
water (L), τ (a−1) is reciprocal of mean residence time in water assuming no radioactive decay (removal to sediments is implicitly included) and λi (a−1) is radioactive
decay constant for radionuclide, i. This factor may be alternatively described as the equilibrium concentration in water Cw,j (Bq/L) for a continuing discharge rate
(Bq/a) [U7]

Dosimetric quantities

Internal dose coefficients from [I7, I8]
ENVIRONMENTAL BEHAVIOUR OF RADIONUCLIDES

Terrestrial

Empirical transfer parameters, primarily based on fallout observations for 137Cs and 90Sr, supplemented by transfer factors for grain for other radionuclides, excepting
I, for which transfer factor for milk applied [U7]
Environmental transfer models presented in [U1, U2] primarily based on empirical data from fallout studies of 90Sr and 137Cs. [U4] cited dynamic models [C1] for thetransfer of radionuclides in terrestrial environments for assessing exposures from nuclear facilities. Transfer coefficients for 90Sr and 137Cs derived in [U3, U4]. [U6]described transfer coefficients as having been derived by regression analysis to models relating measured radionuclide concentrations in diet to annual deposition
density. Approach applied to derive transfer parameters for other radionuclides appears based on transfer parameters for grain, excepting 131I for which transfer
parameter associated with milk was used (in units of (mBq a)/kg per Bq/m3)
131

Aquatic

Transfer parameters derived from [I1, I2]

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

Discharges

3

Factors

Previous approach
EXTERNAL IRRADIATION
Dose coefficients based on [E1] for semi-infinite cloud model and effective dose equivalent rather than effective dose. These factors were modified to allow for acontribution from skin doseRadionuclides
deposited on soil

Dose coefficients derived from [B1]
For short-lived radionuclides, dose rate conversion factor for plane source was applied. For 137Cs, [U7] used dose rate conversion coefficient for exponential profile inground of mean depth of 3 cm. Mean lifetime of radionuclide and average air-to-tissue dose conversion factor applied, with indoor occupancy of 80% and shielding
factor of 0.2 [U7]
INHALATIONRadionuclides
discharged toatmosphereAge-weighted breathing rates and fractions of populations assumed in each age group were presented in [U7]Age-weighted inhalation rate corresponds to 19 m3/d, close to nominal breathing rate of 20 m3/d used in previous assessments (which assumed that collective dose
substantially determined by intake by adults in population). Committee recommended that nominal value appropriate for most applications [U7]. For Committee’s
assessments, population groups specified as infants, children and adults assumed to correspond to ICRP age categories 1–2 years, 8–12 years and >17 years

Resuspension

Dust loading factor of 50 µg/m3 assumed and applied to resuspension of naturally occurring radionuclides in soils

Nuclearinstallations/general

Population- and age-weighted inhalation rates and coefficients applied. Dust loading approach also applied to resuspension of radionuclides in soils

Mine and milltailings/radon

Radon dose factors reviewed in detail in [U7]. Radon dose coefficient consistent with that recommended by Committee in [U8]Generic radon release rates and atmospheric dispersion factors applied to determine local, regional and global components of collective doses (truncated at 10,000
years) per unit electrical energy. Methodologies are outlined in [U3, U4]. Various factors initially derived in 1970s to represent conditions in USA [U3]. Basic
methodology modified in [U6]
The pre-2016 methodology assumed emanation rates of 10 and 1 Bq/s/m2 from tailings at operational and decommissioned mines, respectively [U7] from nominal
release height of 10 m. [U3, U4] used dispersion approach outlined above to determine activity concentrations in air at and beyond 1 km under atmosphericconditions. Dose coefficients of 9 nSv per Bq h/m3 and 40 nSv per Bq h/m3 applied for 222Rn and 220Rn, respectively. Equilibrium factors of 0.4 and 0.8 for indoors
and outdoors assumed (with indoor occupancy of 80%)
INGESTION

Radionuclides
discharged toatmosphereCollective doses from ingestion of radionuclides discharged to atmosphere assessed using environmental transfer factors relating deposition to activity concentrations
in diet ((mBq a/kg) per Bq/m3) to intake (Bq per Bq/m2), from intake to dose (nSv/Bq), and thus from deposition to dose (nSv per Bq/m2) [U7]Specific activity model used to estimate doses from tritium and 14C. Specific activity model for tritium expressed in terms of tritium to hydrogen atom ratio, while for
14
C, specific activity of 14C in ingested food and water assumed to be same as activity per gram of carbon in air at point of interest. [U7] considered this approachprobably overestimates doses
Representative individual consumption rates for following foods presented in [U7] for different geographical areas for milk, grain, leafy vegetables, fruit andvegetables and meat. In practice, combined global value of total consumption rate of all foods (500 kg/a) used to derive transfer factor relating deposition to intake(Bq per Bq/m2). As above, factors relating deposition to diet for caesium and strontium isotopes based on empirical observations from fallout. Corresponding data forother radionuclides based on scaling these factors using transfer information for grain, excepting 131I for which transfer for milk was applied

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENTRadionuclides in air:cloud shine andimmersion exposure

4Factors
Radionuclides
discharged to aquatic
environment

Previous approach
Based on generic assumption of relationship between volume of water and number of people receiving doses from it, validated by global aquatic food-catch data
Collective doses assessed based on following:
Sic = Ai/ V (τ + λi) × ∑k Nkfk,idi

GLOBALLY DISPERSED RADIONUCLIDES
Tritium

Based on simplified model developed 1975 [K1]
Committee’s approach to modelling global circulation of tritium from nuclear installations was based on results from a review and comparison of models [K1], NCRP
[N1], Bergman et al. [B2] and Killough and Kocher [K3]. Concentration of tritium within compartments determined from distribution of tritium in each compartment
divided by volume of water in each compartment. Concentration in humans then determined from concentration in environment weighted by fractional intake fromeach compartment
Most reliable estimate of global collective dose from near-surface atmospheric discharges considered to be given by model by Killough and Kocher [K3] fordischarges to 30°–50° band of troposphere in northern hemisphere, which gave estimate of 2.3 man Sv/PBq. Estimated global collective dose arising from discharges
to ocean available from NCRP [N1] and Bergman et al. [B2] approaches, which indicated that these doses were around one tenth of those from atmosphericdischarges. Collective dose estimate of 0.2 man Sv/PBq for discharges of tritium to ocean thus applied. These global circulation models were reviewed and comparedin some detail [U7] and were considered still appropriate

Carbon-14

Based on a 23-compartment model developed by Titley et al. [T1]. [U7] reported that dose estimates using different models were within a factor of 1.5
The 23-compartment model (see figure VI, annex A of [U7]) was applied [T1] to estimate activity per gram of carbon in each environmental compartment over time.
Atmospheric component adapted from model used by Emanuel et al. [E2], while ocean model accounted for temperature changes, surface areas and varying ice coverin winter. Once mixing achieved, specific activity model used to estimate collective dose commitments from 14C, assuming that specific activity of 14C in carbon
ingested by humans was same as in most relevant compartments for food intake (ground vegetation for terrestrial foods and relevant surface water compartments formarine foods). The incomplete (to 10,000 years) collective effective dose commitment per unit discharge to atmosphere was around 109,000 man Sv/PBq. Doses
following discharge to soils or surface oceans considered to be about the same as for atmospheric discharges, but doses from discharge to deep ocean were around
20% lower [U7]. [K2] found predictions of six models ranged over factor of only 1.5, suggesting remarkable agreement. Attributed to long half-life of 14C relative to
its rate of environmental transport, making estimated dose commitments insensitive to detailed model structure [K2]

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

where Ai (Bq) is activity of radionuclide, i, discharged to water; V (L) is volume of receiving water; τ (a−1) is reciprocal of mean residence time of radionuclide inreceiving water assuming no decay; λi (a−1) is radioactive decay constant for radionuclide, i; Nk is number of individuals for exposure pathway k; fk,i is concentration
factor for item in exposure pathway, k, for radionuclide, i; di (Sv/Bq) is effective dose per unit activity ingested
For calculating collective doses, Committee traditionally assumed crude relationship between number of people and volume of receiving water body. Annual per
caput drinking water consumption, V/Nk, taken to be 2.2 × 107 L [U7]. For freshwater fish NkIk/V assumed to be 4.6 × 10−8 man kg/a/L, based on average fishconsumption rate of 8 kg/a, giving global consumption of 6 × 109 kg/a. This agreed generally with global harvest of 1010 kg [U7], when 50% edible weight was
assumed [U7]
NkIk/V factor for fish and shellfish within continental shelf estimated to be 3 × 10−8 man kg/a/L [U7]. Value noted to be significantly higher than used in [U3].
Residence time, assumed to be that observed for North Sea, of 3 years for 137Cs and 90Sr [C1] and 3.5 years for 239,240Pu (“first pass”) was less than that assumed inearlier reports [U7]5Factors

Previous approach
Global circulation compartment model for 129I developed by Titley et al. [T1] used in assessment in UNSCEAR 2000 Report (see figure VIII, annex A [U7]).
Represented a revision of that developed by Kocher [K4], used in earlier assessments, and modified by Smith and White [S3]. Inventories of stable iodine in modelcompartments, and fluxes between compartments, were derived from environmental measurements and mass balance assumptions. Iodine intakes from eachcompartment were determined from average food consumption and inhalation rates and concentrations of stable iodine in air and foods or by a specific activity
approach. Pathway analysis approach applied, comprising following five pathways: inhalation from land atmosphere (0.29 µg/d); deposition from land atmosphere
onto food crops ingested directly by humans or by dairy or beef cattle (6.6 µg/d); ingestion of land surface water (5.3 µg/d); ingestion of marine fish and shellfish(11 µg/d); root uptake from surface soil (200 µg/d). Equivalent dose to the thyroid and appropriate tissue weighting factor then applied

Krypton-85

Based on simple two-compartment model, originally presented in 1979 [C1]
Committee’s approach for determining global dispersion of 85Kr described in detail in [U5], citing approach presented in [U4], where simple two-compartment model
used to model introduction of 85Kr into northern hemisphere [N2]. Two compartments represented tropospheres of northern and southern hemispheres, and transfer
coefficient of 0.5 a−1 between compartments was used. Activity concentrations in air as function of time [U4]. Time integral of activity concentration in air was 10−10
Bq/m3 per Bq/s. Dose coefficients from activity concentration in air to absorbed dose rate in air and to absorbed dose rate in skin from beta radiation emitted derived
from [C1]
Collective effective dose equivalent derived in [U4] was 0.17 man Sv/PBq (assuming world population of 4 × 109), scaled to 0.2 man Sv/PBq in [U5] for populationof 4.6 × 109. This dose commitment was delivered during first 50 years after discharge. Production of 85Kr for LWRs and GCRs normalized to electricity generated
was 2.3 man Sv/(GW a). The dose, weighted for amount of fuel currently reprocessed (0.05), led to estimate of 0.12 man Sv/(GW a)

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

Iodine-129

6

Table 2. Dose quantities and integration times used in past Committee assessments
UNSCEAR 2008 Report (annex B[U9])

UNSCEAR 2000 Report[U7]

UNSCEAR 1993 Report[U6]

UNSCEAR 1988 Report[U5]

UNSCEAR 1982/1977 Reports[U3, U4] (where specified)Cites [U7]

Cites [U4, U5, U6]

Acknowledged value of dose
distribution information. Purpose oftruncation to derive maximum
future dose equivalent rate frompractice continuing for set time

Integration to 50 or 100 km for local
and to 2,000 km for continental orregional components of collective
dose; most particles from nearsurface discharges deposited within
2,000 km. Ingestion based on timeintegrated concentration factors
used since 1962

Per caput dose equivalent rate
Simplest assumption for population:
uniform density of 100 km−2.
Assumptions for local and regional
components given in annex F.
Average for mining and power
production sites: 3 km−2 for mining
site; 300 km−2 for reactor site up to
100 km; 20 km−2 out to 20,000 km
Integration for shorter-lived
radionuclides assumed world
population of 4 × 109; for 14C and129
I, assumed increases to 1010 andthen constant

GLOBALLY DISPERSED RADIONUCLIDES
3

14

85

129

H, C, Kr and I: doses(man Sv/(GW a)) truncated to
100 years: 3H: 0.004; 14C: 6.3;
85
Kr: 0.12; 129I: 0.0008 [U5]14

C 9% of total dose commitment
from single discharge delivered in
100 years; 23% in 1,000 years; 75%
in 10,000 years [T1]. Truncation
time depends on period of nuclear
power use. Population stabilizes at1010 for 14C and 129I; 5 × 109 for 3H
and 89Kr

Truncation at 10,000 years bywhich time contributions of 3H and85
Kr insignificant. 14C: 70% of dose
commitment calculated for all time.
Globally dispersed contribution
almost entirely due to 14C

Results for alternative truncation
periods provided

Integration times in 1977 for global
components: 101, 102, 104, 106, 108
years
Only 10% 14C dose delivered in
70 years

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

GENERAL METHODOLOGY

7

UNSCEAR 2008 Report (annex B[U9])

UNSCEAR 2000 Report[U7]

UNSCEAR 1993 Report[U6]

UNSCEAR 1988 Report[U5]

UNSCEAR 1982/1977 Reports[U3, U4] (where specified)

Truncated dose commitment for
10,000 years. Data given for 100,
1,000, 5,000 and 10,000 years.
Different assumptions on continuationof nuclear power: maximum 500
years, with greater contribution foralternative means, so that mining andmilling complete in 100 years

Primary release airborne.
Population density 3 km−2 withinfew 100 km; uniform population of
25 km−2 to 2,000 km [U3]MINING AND MILLING
Cites [U3, U4]. Unchanged releaseover 10,000 years. Population
density: 3 km2 at 0–100 km; 25 km2
at 100–2,000 km. Comparisons withactual sites included

1.5 man Sv/(GW a) is 3 times
greater than 1988 value. Assumed
duration of release 10,000 years—
maximum period of integrity oftailings piles (and 230Th and 222Rn
release); after this erosion completeor covered with ice
FUEL FABRICATION

0.003 man Sv/(GW a)—nospecific references

Cites [U6], same value as annex B
of [U9]. Collective dose to local
population (3.1 × 106 within 50 km)
and corresponding individual dose
10 µSv/aAssumed located in northern
Europe or North America

POWER PRODUCTION
Cites [U7], local and regional
components; model site,
population density 400 km−2 in 50
km radius; regional 20/km−2 in
2,000 km radius. Values for man
Sv/PBq from [U7]Some changes to calculation factors
for some radionuclides applied in[U4, U5]—differences presented
but not explained[U3]: dose per unit discharge for noble
gases presented for 1–10, 10–100 and
100–1,000 km. Collective dose
commitment chosen to reflect dose
received by most exposed individuals.
Page 262 gives cumulative population to
2,000 km and within 50 km

Cites [U5]. Population within 2,000
km is 250 million. Average within
50 km of 400 km−2 referenced tositing practice

REPROCESSING
Cites [U6]

Cites [U6]

Cites [U5]
WASTE

L and ILW disposal
0.5 man Sv/(GW a) [U4, U6]

L/ILW releases to groundwater 0.5
man Sv/(GW a) and from handlingspent fuel 0.05 man Sv/(GW a)
TRANSPORTATION

Transportation of spent fuel: 0.1 man
Sv/(GW a) cites [U2, U4, U7]
Other transport (incl. non-nuclear)verifiably low–detailed discussion

Transportation of 0.1 man
Sv/(GW a) based on [U5]Times at which dose delivered
presented (table 54 of [U5])ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

Cites [U3, U4]: 0.2 operational
and 0.00075 man Sv/(GW a)
residual8

Table 3. Distances used to define local and regional components of collective dose in UNSCEAR reports since 1972
UNSCEAR 1977
Report [U3]

UNSCEAR 1982
Report [U4]UNSCEAR 1988
Report [U5]

UNSCEAR 1993
Report [U6]

UNSCEAR 2000
Report [U7]

UNSCEAR 2008
Report [U9]Definition of local
and regional
components

Local component
discussed as distinct
from global
component, but
contributions toannual collective
dose not presented
separately

Subdivision of world
population. Local
and regional
components
estimated for 1–100
and 100–1,500 km,
respectively

Local and regional
populations
described as being
within few hundredand few thousand
kilometres,
respectively. Local
and regional
components notseparated indefinition ofcollective doseparameters

Local populationreferred to as thosewithin about 100 km
and regional within
about 1,000 km. Thisdefinition was notdescribed in terms ofdispersion or dose
distributions

Approach based onthat presented in1982 and 1988

The integrated doseto 50 or 100 km todefine local
component, withfurther integration to
2,000 km to define
regional orcontinental
component

Based on approach
outlined in [U7]

Other related issues

Some examples ofsite-specific local
exposures

Doses from noble
gases as function of
distance (1, 10, 100,
1,000 km)Basis for models ofrepresentative sites
for each stage of
nuclear fuel cycle onwhich later
assessments werebased.
Population
distributions definedfor distances 0–100
km and 100–2,000km

Representative sitespecific criticalgroup doses forperspective on
individual doses

Sensitivity of dose
estimates toatmospheric dispersion
assumptions, including
stack height,
considered. Gaussian
plume model overdistances >100 km
considered appropriate
for populationassessment because of
implicit averaging

Population anddistribution assumed
to continue
indefinitely. World
population of 4 × 109
assumed; for longlived nuclides,
assumed to increase
to 1010 and then stay
constant

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENTUNSCEAR 1972
Report [U2]9Table 4. General factors and parameters used in Committee assessments since 1977
UNSCEAR 2008 Report[U9]
Methodology referenced to[U7]Radionuclide composition

90% activity of particulates
discharged assumed
composed of: 54Mn, 58Co,
60
Co, 89Sr, 134Cs, 137Cs and140
Ba (including 140La). 10%of activity assumed composedof: 51Cr, 59Fe, 65Zn, 90Sr, 90Y,
95
Zr (including 95Nb), 124Sb,
136
Cs, 141Ce and 144Ce

Atmospheric dispersion

Long-term average dispersion
based on Gaussian plumemodel fitting gave simplified
dilution factor at 1 km
(5 × 10−7 Bq/m−3 per Bq/sdischarged) and further
reduction in inverse
proportion to the 1.4 power of
distance from the discharge
point. The value of D1 waslower than in 1982; owing towind direction assumptions—
uniform wind rose. Value of ntaken to be 1.2 for noble
gases which do not deposit

UNSCEAR 1993 Report[U6]

UNSCEAR 1988 Report[U5]

Environmental anddosimetric models andparameters referenced to[U5][U4] considered stillvalid for assessing
impact of discharges
from fuel cycle, although
reprocessing treateddifferently in 1988.
Fractions of fuelreprocessed added tocontributions from rest offuel cycle

UNSCEAR 1982/1977 Reports[U3, U4] (where specified)

Activity of particulates assumed
comprised of equal distributionof: 51Cr, 54Mn, 59Fe, 58Co, 60Co,
65
Zn, 89Sr, 90Sr, 90Y, 95Zr, 95Nb,
124
Sb, 134Cs, 136Cs, 137Cs, 140Ba,
140
La, 141Ce and 144Ce

Models and parametersreferenced to [U5]

Statistical methods consideredadequate for long-term averageassessments for routinedischarges; Gaussian plumerecognized as most useful andcommonly used. Simplified
relationship derived to estimate
time integrated air
concentrations.a Assumed windblows towards location 50% oftime

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

GeneralUNSCEAR 2000 Report
[U7]

10

UNSCEAR 2008 Report[U9]

UNSCEAR 2000 Report[U7]

UNSCEAR 1993 Report[U6]

UNSCEAR 1988 Report[U5]

UNSCEAR 1982/1977 Reports[U3, U4] (where specified)

Variability of results tochanges in input parameters
demonstrated; D1 insensitive
to wind speed and dischargeheight, while n sensitive tothese and deposition.
Uncertainties at regional
scales acknowledged large,
but probably within factor of
10 for simple situations

Accuracy of equations consideredby Hoffman et al. [H1]; withinfactor of 10

Discharge height

Representative effective
discharge height of 30 m used
for nuclear installations

Effective release height of 10 m
used for mines and mills
Height of release considered tohave little effect on collective
dose estimates

Deposition

Effective deposition velocityof 0.002 m/s for annual
average deposition. Value
appropriate for dry
deposition; range for wet anddry deposition 0.005–0.013
m/s, depending on downwind
distance. Larger deposition
velocity values inconsistent
with dispersion assumptions
on mass balance

Aquatic dispersion(freshwater)

Mean residence time of 90Sr
and 137Cs assumed to be 3 and5 years, respectively.
Radionuclides with high Kd(144Ce and 239Pu) assumed tobehave as 137Cs, others as
90
Sr, correcting forradioactive decay

In 1979, model for isolated water
body applied. Removal ofradionuclides onto sediment using
distribution coefficient [C1]bRiver model based on [C1], itself
based on observation that average
activity concentrations intransversely well-mixed riverwater decreased exponentiallywith distance c

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

Uncertainty in dispersion
modelling

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UNSCEAR 2008 Report[U9]

UNSCEAR 2000 Report[U7]
Residence times for North
Sea assumed representative of
all coastal seas. Mean
residence time assumed to be
3 years for 90Sr and 137Cs [C1]and 3.5 for 239Pu (“first pass”)

Drinking water intake

V/Nk (where Nk is number ofpeople exposed by particularpathway and V is volume ofwater in water body) used toindicate water use forparticular pathway. For
drinking water: 2.2 × 107
L/person assumed

Fish and seafood intake

Average intake by individual:
8 kg/a (6 kg/a marine fish;
1 kg/a each for freshwater
fish and shellfish) ranging
from 4 to 6 in West Asia andAfrica to 10–14 kg/a in East
Asia and Europe. NkIk/V from
freshwater fish estimated as
4.6 × 10−8 kg/(a L). For salt
water fish and shellfish the
NkIk/V value estimated to be
3 × 10−8 kg/(a L)

Concentration factors for fish

Values taken from [I2] forfreshwater and [I1] for marine
foods

Age groups

Noted that few assessments
included estimates of doses tochildren, but intakes by infants(1 year), children (10 years)
and adults provided in table 8of annex B

Fractional age distribution
and intakes noted in 1993
used [U6], together with agedependent dose coefficients“for most purposes” for age
groups: 1-2, 8–12 and >17
years

UNSCEAR 1988 Report[U5]

UNSCEAR 1982/1977 Reports[U3, U4] (where specified)
Simple single compartment model(for isolated waters) assumed toapply, extended to include
interactions with adjacentcompartments, of type describedin [C1]

Age-weighted annual
intakes of naturally
occurring radionuclides
derived assuming
fractional distribution of
adults, children andinfants in population of:
0.65, 0.3 and 0.05

Doses to 0–1-year-age group from
I considered in 1977; 6 months,
4 years and 14 years also
considered for 131I from nuclear
reactors in 1982
131

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

Aquatic dispersion (marine)

UNSCEAR 1993 Report
[U6]

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UNSCEAR 2008 Report[U9]

UNSCEAR 2000 Report[U7]

UNSCEAR 1993 Report[U6]

UNSCEAR 1988 Report[U5]

UNSCEAR 1982/1977 Reports[U3, U4] (where specified)

EXTERNAL IRRADIATION
Relationship between air
kerma and absorbed dose
Specific reference made to useof occupancy and shielding
factors for indoor occupancy

Recalculation identified asnecessary in future for
effective dose rather thaneffective dose equivalent

Modification of factors based on
effective dose equivalent (HE)using 0.01 Hskin to simulate
effective dose (E) first used in1982 for noble gases

Cloud shine and immersion

Approach referenced to [U4]and [E1]

Coefficients from [C1], based onsemi-infinite cloud model

External irradiation from
deposition

Based on dose rate conversion
coefficients from [B1]. No
account taken of different
behaviour of radionuclides inurban and rural environments(except for Chernobyl
accident)
INHALATION

Inhalation rate

Breathing rates from [I8]Dose coefficients

Age-dependent dosecoefficients from [I7, I8]

Dose coefficients for radon

Dose conversion convention
from [I6] giving dosecoefficients in range 6-15
nSv/(Bq h/m3) supporting useof previous value of
9 nSv/(Bq h/m3). For 220Rn,
value of 40 nSv/(Bq h/m3),
including dose from 214Pb
derived by analogy with risk
factors from [I5]

Breathing rate of 20 m3/d, close tothat given in [U4]Nominal breathing rate of
20 m3/d assumed;
collective dose assumed
dominated by intake byadults
Dose coefficients for
adult workers from [I3,
I4]
Dose coefficient for
Rn, in equilibrium with
its short-lived progeny of
9 nSv/(Bq h/m3)
222

Dose coefficient for
Rn, in equilibriumwith its short-lived
progeny of
9 nSv/(Bq h/m3)
222

Dose coefficients for adult
workers from [I3, I4]

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

External dose factors

Assumed equivalent; charged
particle equilibrium

13

UNSCEAR 2008 Report[U9]

UNSCEAR 2000 Report[U7]

UNSCEAR 1993 Report[U6]

UNSCEAR 1988 Report[U5]

UNSCEAR 1982/1977 Reports[U3, U4] (where specified)Time-dependent resuspension factor
applied; initial and intermediatefactors of 10−5 and 10−9 m−1,
respectively. Decay constants for
initial and longer-term decline inresuspension factor: 1.46 × 10−7 s−1
and 2.2 × 10−10 s−1

Resuspension (of naturally
occurring radioactive
material)

Dust-loading factor of 50 µg/m3
assumed in [U3, U4], appropriate
for long-lived radionuclides,
uniformly mixed in soil surface

Environmental transfer

Compartment models and transferfrom [C1] used to derive matricesof time integrals of activities ofradionuclides in unit mass of foodover different time periods
INGESTION

Water intake rates

500 L/a for adults, 350 L/a forchildren and 150 L/a for infants

Ingestion rates

Applied values from [U5].
Rates categorized as western(greater amounts of dairy
products and meat) andeastern (grain products,
vegetable products and fish)

Food preparation losses

Not included in Committee’s
calculations

Age-dependent
consumption rates derived.
Milk consumption 120 kg/a
and 110 kg/a for infants andchildren, respectively(compared with average of
500 kg/a). For other foods,
assumed children eat two
thirds and infants one thirdof adult values [U7]

Population-weighted
consumption rates

Dispersion approximation: χa (x) = A0 f (x/x1)-p, where χa (x) is the time-integrated concentration of the radionuclide in air at distance x; x1 (normalization distance) = 103 m; A0 is the source activity, f is a coefficient withunits s/m3, and p is a numerical exponent. For most weather categories and discharge heights, a reasonable approximation is obtained for f = 3 × 10−6 s/m3 and p = 1.5, within 100 km.
bChange in activity concentration with time in isolated water body: dχw/dt = A0/V – (λτ + λs + λ) χw, where χw is the activity concentration per unit volume in the water at time t; A0 is the rate of input of activity; V is thevolume of water; λτ is the fractional rate of renewal of water; λs is the fractional rate of removal of activity by sorption onto sediments and λ is the radioactive decay constant.
cRiver dispersion: activity concentration χw in water (including suspended sediments) at distance x is: χw(x) = A0/V e-kx, where V is the volume flow rate of the river; k is a coefficient dependent on the river and radionuclide,which is given by k = (λ + λs)/v, where v is the river velocity and other parameters are as given above.
a

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

Resuspension (ofradionuclides from nuclear
power production)

14

Table 5. Assumptions and factors included by the Committee for assessing collective doses due to radon emissions from mines and mill tailings, andin three papers that consider their applicability to particular sites
Factor

Reference

Uranium fuelrequirements

UNSCEAR 2000 Report[U7]

UNSCEAR 1993 Report[U6](250 t U308) per
GW(e) a210 t U (250 t U308) per
GW(e) aTailings surface area
normalized toelectricity generated

Similar approach to [U6]:
3 TBq/(GW a) operational,
and 1 TBq/(GW a) fromabandoned but stabilized
tailings

10 Bq/s/m2 fromoperational, 3 Bq/s/m2
from abandoned but
stabilized tailings

After decommissioning,<7 Bq/s/m2. For longterm management withwater coverage, emission
rate 0–0.2 Bq/s/m2

Underground mines
75 TBq/(GW a);mills 3 TBq/(GW a)

3 TBq/(GW a)
operational;
1 TBq/(GW a) fromabandoned but
stabilized tailings

0.946 TBq/(GW a)

3 km−2 at <100 km and
25 km−2 at
100−2,000 km

Used 100 × 100 km grids
around sites in Canada and
Mexico; compared withuniform density; reduced
population densities:<3 km−2 at <100 km,
2-7 km−2 at 100-2,000 km

63 km−2 at 0-100 km,
44 km−2 at
100-2,000 km for
Lodève mining site

3 × 10−6 Bq/m3 per Bq/s

Used US EPA ISC3amodel for 1–100 km and
CALPUFF/CALMETb
for 100–2,000 km.
Reduced concentration at
10 km by factor of 2 andat 2,000 km by 17

Atmospheric dispersion
modelling

Release height

10 m

10 m

5 × 10−7 s/m3

Mudd
[M2]

0.95 ha/(GW a)

1 Bq/s/m2, taking
account of informationin [S1] and that someareas are to berehabilitated

Population density

Air dispersion factor
at 1 km

Tort et al.
[T2]

1 ha/(GW a)

Radon release rate

Radon emission ratenormalized toelectricity generated

SENES
[S1]

Release rate from
Lodève site before
remediation:
28 Bq m−2 s−1. After
remediation, radon flux
almost zero

Up to 11.6 GBq/d (fromtailings, waste rock andlow grade ore) comparedwith Committee’s
approach, which implies
2.6 GBq/d (tailings only)

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENTUNSCEAR 2008 Report
[U9]

15

Factor

Reference
UNSCEAR 2008 Report[U9]

UNSCEAR 2000 Report
[U7]

SENES
[S1]

9 nSv/h per Bq/m3 (EEC)
40 nSv per Bq h/m3 (EEC)
for thoron from [U8]6.4 nSv/h per Bq/m3(EEC) derived from [I6]cRadon progeny
equilibrium factors

0.4 (indoors 80%)
0.8 (outdoors 20%)

Suggests 0.6 more
appropriate based on
European and US studies

Collective effective
dose factor

0.015 man Sv/TBq

Truncation period
Collective effective
dose (range)

0.2 man Sv/(GW a)
operational, and 0.00075
man Sv/(GW a) fromresidual tailings

Annual effectivedose

40 µSv (assumingcollective dose received bypopulation <100 km)

Relevant comments
noted in references

Dosimetry consistent withannex E of [U8]9 nSv/h per Bq/m3(EEC)

10,000 years

10,000 years

10,000 yearsd

0.2 man Sv/(GW a)
operational, and 0.00075
man Sv/(GW a) fromresidual tailings

150 (1–1,000)
man Sv/(GW a)

0.96 man Sv/(GW a). In
Committee’s evaluation,
quoted as 1.4 man Sv/(GWa) over 10,000 years usingradon dose coefficient
specified by Committee

380 man Sv/(GW a)(from unremediatedsite)

Individuals within
10 km 20 µSv (fromunremediated site)
Imperceptible fromvariations in normal
background dose rates
from natural sources

Up to 97% dose topopulation within 100–
2,000 km. Unclear
whether radioactive
decay taken into accountin Committee’s estimates

Committee’s data forsolid waste parameters
reasonable althoughmajor sources (waste
rock and low grade ore)lead to underestimation

Higher population
densities around mills in
China

Population grids lead toestimates of collective
dose factor of 3–4 lower
than uniform distribution

Given level of variation, using
rates normalized to electricity
generated (expressed per
GW a) unrealistic

See http://www.epa.gov/ttn/scram/dispersion_alt.htm#isc3.
See http://www.src.com/calpuff/calpuff1.htm.
cBased on 4 mSv/WLM. SENES [S1] noted lower conversion factors are used in some epidemiological studies (<2 mSv/WLM).
d
SENES [S1] states that this is used by the Committee for the sake of illustration.
b

Mudd
[M2]

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

9 nSv/h per Bq/m3(EEC)

Dose conversion
factorTort et al.
[T2]

x−1.5 (x in km)

Concentration with
distance, xa

UNSCEAR 1993 Report
[U6]

16

Table 6. Development of the Committee’s approach for assessing exposures from globally dispersed radionuclides
FactorUNSCEAR 2008 Report[U9]
Cites [U5]

Truncation period

10,000 years

UNSCEAR 1993 Report[U6]

UNSCEAR 1988 Report[U5]

UNSCEAR 1982 Report[U4]

States that environmental
transfers of 3H, 14C, 85Kr
were established, and that
reliable estimates made in[U4]a10,000 years

10,000 years

Global population

For 14C and 129I assumed 1010
at time of discharge; for 3H
and 85Kr, 5 × 109 assumed

Reprocessing

Weighting for reprocessing
0.11 for period 1990–1994

10,000 years b

Reprocessing plantdischarges weighted byfraction of energy value of
total nuclear fuel reprocessed(5%)

Model reprocessing facility
described. All reactor fuelassumed to be reprocessed

TRITIUM
Basis

Collective dose factor

Range of models discussed,with range of complexity.
Value to consolidate results
0.004 man Sv/(GW a)

2 and 0.2 man Sv/PBq for
atmospheric and aquatic
discharges from nuclear
installations, respectively

Simple model by [K1], as
implemented in [C1]3.2 × 10−5 man Sv/PBq for
population of 4.6 × 109
Totalc: 0.004 man Sv/(GW a)

Incomplete dose
commitments

Table 70 of annex B of [U5]:dose received in first few
years

Local and regional
component

Add 0.6 man Sv/(GW a)(factor >100 greater thanglobal contribution)

2.8 × 10−5 man Sv/PBq for
population of 4 × 109

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

Overall approach

UNSCEAR 2000 Report
[U7]

17

FactorUNSCEAR 2008 Report[U9]

UNSCEAR 2000 Report[U7]

UNSCEAR 1993 Report[U6]

UNSCEAR 1988 Report[U5]

UNSCEAR 1982 Report[U4]

CARBON-14
Basis

6.3 man Sv/(GW a)

Delivery of dose commitment

Approach developed in [E2]

Used [C1]. Compartments: two hemispheres, comprising
humus, circulating carbon surface and deep ocean. 14C
assumed instantaneously mixed in compartment into which
discharge occurs. Results similar to those produced from
more complex models

Complete commitment perunit discharge of 109,000
man Sv/PBq (population of1010)eIncomplete collective dose
commitment of
85 man Sv/TBq (populationof 1010)67 man Sv/TBq average for both atmospheric and aquatic
discharges (population of 1010)f. Total: 6 man Sv/(GW a)

9% of commitment fromsingle discharge delivered
within 100 years, 23% within
1,000 years and 75% within
10,000 years g

Above commitment delivered over 10,000 years
Table 70 of annex B [U5]: 3% in 10 years; 10% in 100 years
and 19% in 1,000 years

IODINE-129
Basis

Titley et al. [T1] and revisionof Kocher [K4]h. Collective
doses with time fromdifferent discharges

2.2 GBq/(GW a)i

Reprocessing
Collective dose factor(man Sv/(GW a))

Future global population of 1010; 1.4 × 104 man Sv/TBq;
0.003% delivered in 100 years; 0.03% in 10,000 years and
5% in 106 years. Most of the commitment received between
10 and 40 million years
Incomplete commitment to 106 years used: 700 man Sv/TBq

106 years: 1.5; 10,000 years:
0.0093; and 100 years 0.0008

0.008
KRYPTON-85

Basis

Reference to 1982 ReportTwo-compartment modelcomprising the tropospheresof the northern and southernhemispheres. Exchange rateof 0.5 a−1 assumed [C1]

Collective effective dose
commitment per discharge

0.2 man Sv/PBq (population
4.6 × 109)0.17 man Sv/PBq(population 4 × 109)

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

Collective effective dose
commitment factor

Model comprising 23
compartments [T1],illustrated in figure VI ofannex A of [U7]. Terrestrial
model adapted from [E2],with minor modification d18FactorUNSCEAR 2008 Report[U9]Time for delivery of dose
commitment

a

b

c

d

e
f

g

h

i
j

UNSCEAR 1993 Report[U6]

UNSCEAR 1988 Report[U5]
Within 50 years

0.12

UNSCEAR 1982 Report[U4]
Inert gas disperses throughatmosphere and achieves
uniform concentration in
2 years

Normalized production of85
Kr for different reactor
types j; weighted by 0.12, thefraction of fuel reprocessed

The UNSCEAR 1988 Report [U5] also stated that 129I posed a problem because of its very long half-life and the uncertainties in predictions over tens of millions of years—and “therefore little use can be made of thesecollective dose commitments for decision-making purposes”.
Results for alternative integration periods were presented. Results for 106 years presented and discussed (for 129I); it was stated that incomplete collective dose commitments are useful to demonstrate time distribution ofdose and to estimate per caput doses arising per year from finite duration of practice.
Atmospheric discharge from reactor operations: 46 TBq/(GW a); aquatic discharges: 40 TBq/(GW a). Reprocessing (averaged over Sellafield and Cap de la Hague) aquatic and atmospheric discharges add up to
600 TBq/(GW a). Since only 5% fuel is reprocessed, this adds 30 TBq/(GW a) to reactor discharges.
Unchanging global inventory of carbon assumed. The ocean model takes account of temperature changes, surface areas and varying ice cover in winter. Exchanges between oceanic and atmospheric compartments are
based on estimates of the dissolution of CO2 from [M1] and [S2]. The model was tested and validated.
Table 44 annex C of [U7] gives collective effective dose commitment (10,000 years) due to globally dispersed radionuclides from reactors and reprocessing.
Reactors: 57 man Sv/(GW a) from HWR, LWR, LWGR, GCR operation. Normalized discharges from reprocessing averaged over Sellafield and Cap de la Hague (3.5 TBq/(GW a) for Sellafield and 0.66 TBq/(GW a)
for Cap de la Hague). This represents for Sellafield, 234 man Sv/(GW a), and for Cap de la Hague, 44 man Sv/(GW a). Taking account of 5% fuel reprocessed annual value averaged over the two sites, the total is
6 man Sv/(GW a).
The UNSCEAR 2000 Report [U7] states this is similar to other estimates: Killough and Rohwer [K2] found estimates from six models ranged over a factor of only 1.5. The UNSCEAR 2000 Report [U7] also stated thatthe maximum annual dose for continuing practice was 1 µSv, and that limited practice of nuclear power generation would lead to progressively lower annual doses.
Model assumes circulation compartments (figure VII, annex A [U7]) for atmosphere, hydrosphere, lithosphere, and terrestrial. Fluxes determined from environmental measurements and mass balance. Assumes mean
residence time in surface soil of order of 10,000 years, mixing in the ocean 1,000 years. [U7] states that global iodine cycle and dynamic behaviour of iodine is being further studied. Iodine measurements in vicinity of
nuclear installations markedly higher and retained in surface layer <10 cm.
Discharges from Sellafield and Cap de la Hague normalized to electricity generated were 40 GBq/(GW a) to sea and 4 GBq/(GW a) which, when weighted for 5% fuel reprocessed gives 2.2 GBq/(GW a).
For LWRs, the factor is 11.5 PBq/(GW a) or 2.3 man Sv/(GW a); for GCRs the factor is 14 PBq/(GW a) or 2.8 man Sv/(GW a).

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

Collective dose factor(man Sv/(GW a))

UNSCEAR 2000 Report
[U7]

19

Table 7. Development of the Committee’s approach for assessing impacts of non-nuclear forms of electrical energy production
FactorUNSCEAR 2008 Report[U9]

UNSCEAR 2000 Report[U7]

Key issues

Focus on coal mining andpower production from coal.
Additional literature sourcesreferred toUpdates the UNSCEAR
1993 Report but detailed
methodology referenced to
the UNSCEAR 1982 Report

UNSCEAR 1988 Report[U5]

UNSCEAR 1982 Report[U4]

Three different aerosol
capture methods and one
with different sitecharacteristics assumed

Initial consideration of oil,peat, natural gas

Coal and geothermal sources
only; detailed specificationof dose assessment
methodology used insubsequent reports

Slightly modified assumptions
on proportions of sitecharacteristic of coal energy
production. Data for China
significantly different fromdefault for OECD countries. In
China, assumed usage
representative of non-OECD
countries; average worldwide
use of coal assumed as follows:
40% coal used for energy
production, 50% by otherindustries and 10% in dwellings

Main difference between[U5] and [U4] is duelassessment of discharges
from coal-fired power
stations with different
capture efficiencies.
Additional source
information on geothermal
and initial consideration ofoil, natural gas and peat forenergy production

Provides the basis formethodology

ENERGY PRODUCTION FROM COAL
Annual coal production

Annual world production ofcoal: 3.7 × 1012 kg in 1979.
Percentage use in energy andhousehold fuel varied
between countries

Coal mining

Primarily occupational
exposure; maximum
collective effective dose
equivalent of 3 man
Sv/(GW a)
Reference to crude approach
included in [U5]Two approaches used todetermine release of radon in
exhaust air, estimates of 30
and 800 TBq, collective
effective dose equivalent of
0.5 and 10 man Sv

Public exposure estimated on
basis of emission of radonfrom coal ore, mass of ore
required per unit ofelectricity generated, meanradon concentration in coal

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

GeneralUNSCEAR 1993 Report
[U6]

20

FactorUNSCEAR 2008 Report[U9]

UNSCEAR 2000 Report[U7]

UNSCEAR 1988 Report[U5]

UNSCEAR 1982 Report[U4]

Use of coal

See above general statement

Mass of coal for power
production assumed from[U4]

3 × 109 kg of coal assumed to
produce 1 GW a

Activity concentration in
coal

Assumption about activity
concentration in coal from
[U4]

Assumption about activity
concentration in coal from
[U4]

Assumed activity
concentration of 20 Bq/kg
each of 238U and 232Th inequilibrium with theirprecursors. Noted possible
exceptions of 210Pb and210
Po; enhanced activity of210
Pb may occur if large
quantities of 222Rn diffuse
from adjacent rocks

Activity concentration in ash

Cites [U5]Large power plants assumed
to give rise to 20% bottom
ash and 80% fly ash. Activity
concentrations in fly ash
from [U4] applied.
Enrichment factor of 3 for210
Pb and 210Po assumed

Radionuclides partitioned
between bottom and fly ash.
Averages in escaping ash(Bq/kg): 265 for 40K; 200 for
238
U; 240 for 226Ra; 930 for
210
Pb; 1700 for 210Po; 70 for
232
Th; 110 for 228Th; and 130
for 228Ra

Fly ash release

Two types of station
assumed; one that releases
around 10% of fly ash while
the other releases 0.5%

Average concentrations in fly
ash escaping through stack
depend on filtration. Small
particles caught lessefficiently and some traceelements concentrated on
small particles. Modelledusing an enhancement factorof 1–11 for 210Po and 210Pb
and 1–2 for uranium, radium
and thorium isotopes

Activity concentrations
released

Applies assumptions from
[U4]

220

Rn released per GW a;
60 GBq assuming all radon
contained in coal isdischarged to atmosphere

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENTUNSCEAR 1993 Report
[U6]

21

FactorTechnology-related factors

UNSCEAR 2008 Report[U9]

UNSCEAR 2000 Report[U7]

UNSCEAR 1993 Report[U6]

UNSCEAR 1988 Report[U5]

Release depends on
temperature of combustionand efficiency of filtration.
Two types of system inplace: those withsophisticated retention
devices releasing 1% of ash,and those with lesssophisticated systems where
10% is more reasonableestimate. Assumption: plantburning coal with 10% ash
content and 97.5% retention
in filtration systems.
Enrichment factor 3 for 210Po
and 210Pb and 1 for otherradionuclides

Radon releases

Applies data and approachfrom [U4]

Carbon-14 discharges

Discharge of activity-freecarbon dioxide reduction incollective effective dose
commitment of 60
man Sv/(GW a)

Use of ash

5% ash production used inconstruction of buildings.
External dose ratemeasurements indicate thatwooden and concrete houses
give rise to annual effective
doses of 30 and 70 µSv,
respectively

Release of 222Rn and 220Rn
assumed in equilibrium with238
U and 232Th in coal anddischarged in their entirety.
Average activity
concentration 20 Bq/kg andcombustion of 3 × 109
kg/(GW a) give estimatedrelease of 60 GBq/(GW a)

Use in manufacture of
cement and concrete, as aroad stabilizer

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

Three types of plantconsidered: one thirdassumed modern; one third
old and the remaining third
characteristics based on
Chinese data. Collective dosenormalized to electricity
generated 20 man Sv/(GW a)

UNSCEAR 1982 Report
[U4]

22

FactorUNSCEAR 2008 Report[U9]

UNSCEAR 2000 Report[U7]

UNSCEAR 1993 Report[U6]

UNSCEAR 1988 Report[U5]

UNSCEAR 1982 Report[U4]

OTHER FORMS OF ENERGY PRODUCTION
Data and method referenced
to [U5]2 × 109 kg oil assumed needed togenerate 1 GW a of electricity.
Estimated discharge to generate
1 GW a derived frominformation on plants in France.
When normalized to electricity
generated, levels similar todischarges from coal-fired plants
with efficient aerosol capture.
Collective effective dose
equivalent 0.5 man Sv/(GW a)

Peat

Data from [U5] cited; noestimate of worldwide
impact made owing to lackof information on worldwide
production

Finland and Sweden process;average 238U concentration inpeat of 40 Bq/kg and dust control
efficiency of 99% assumed(together with generalassumptions applied for coal
fired power stations) and 5 × 109kg of peat needed to produce
1 GW a; collective effective dose
commitment: 2 man Sv/ (GW a).
No assessment of total collective
dose

Natural gas

Data from [U5] cited

Typical value for radon
concentrations in natural gas
taken to be 1,000 Bq/m3.
2 × 109 m3 natural gas
required to produce 1 GW aof electrical energy, radon
emission 2 TBq,
corresponding to 0.03 man
Sv/(GW a). Assuming 15%
world production of naturalgas (1012 m3) used forelectrical power, collective
effective dose equivalent is
3 man Sv

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

Oil

23

FactorUNSCEAR 2008 Report[U9]

UNSCEAR 2000 Report[U7]

UNSCEAR 1993 Report[U6]

UNSCEAR 1988 Report[U5]

UNSCEAR 1982 Report[U4]
Annual release of radon estimatedbased on literature survey. Data
from Italian plants suggest
average atmospheric discharge of
222
Rn of 400 TBq/(GW a).
Resulting collective effective dose
equivalent commitment 6 man
Sv/(GW a). Individual effective
dose: 30 µSv to critical groupliving at 1 km from geothermal
plant of 1 GW (100 m stackheight)Environmental levels anddoses

Equilibrium factor between radonand short-lived progeny 0.8

Equilibrium factor between radonand short-lived progeny 0.6

Inhalation dose

Effective dose equivalent perunit activity of radon inhaled
1.1 × 10−8 Sv/Bq

No decay assumed; calculation
based on integrated atmosphericconcentration at ground levela

Data from [U5] cited

Dose from 222Rn and short-lived
progeny compared with natural
emanation rateb

Dose from depositiona

Evaluated from comparison withnatural soil activity concentrations
and annual absorbed doses intissues from naturally occurring
radionuclides. Deposited activity
assumed to have mean life of 100
years and upper 30 cm involved
in uptake.c Deposition onvegetation and foods not taken
into accountCollective dose commitment from inhalation is given by:
Mcq = A0/vdS × SδNB × Dq/Iih
A0/vdS is the integrated atmospheric concentration at ground level (Bq s/m3); S is the area in which deposition occurs, δN is the population distribution (10−4 m−2); B adult breathing rate (2.3 × 10−4 m3/s) and Dq/Iih is thecommitted absorbed dose to organ or tissue q per unit activity inhaled. A quality factor of 20 for α particles assumed. 80% assumed insoluble in line with ICRP [I6].
bCollective dose commitment from inhalation of 222Rn and short-lived progeny:
Mcq = A0/S × 1.8 (Bq/m3)/2 10−2 (Bq/m2/s) SδNB × Dq/Iih
Equilibrium factor between 222Rn and progeny 0.6; average outdoor equilibrium equivalent concentration: 1.8 Bq/m3; average emanation rate of 222Rn 2 × 10−2 Bq/m2/s.
cCollective dose commitment from deposited material:
Mcq = A0DqδNτ/hC
Dq is the natural dose rate in organ q; δN is the population density; τ is the mean life in soil (100 years); h is the thickness of soil expressed as mass per unit area (assumed to be 500 kg/m2) and C is the naturalconcentration of the radionuclide in soil.

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

Additional plant data
available suggesting
atmospheric discharge ofaround 150 TBq/(GW a)

Geothermal energy

24

ELECTRONIC ATTACHMENT 2: SUMMARY OF THE COMMITTEE'S PRE-2016 METHODOLOGIES AND THEIR DEVELOPMENT

25

References
B1
B2

C1

E1

E2

H1

I1
I2
I3
I4
I5
I6
I7

I8

K1

K2
K3
K4
M1

M2
N1
N2
S1

Beck, H.L. Exposure rate conversion factors for radionuclides deposited on the ground. EML-378.
Environmental Measurements Laboratory, Department of Energy, New York, 1980.
Bergman, R., U. Bergström and S. Evans. Environmental transport and long-term exposure for tritium
released in the biosphere. pp.535-554 in: Proceedings of the International Symposium on the Behaviourof Tritium in the Environment. International Atomic Energy Agency, Vienna, 1979.
CEC. Methodology for evaluating the radiological consequences of radioactive effluents released innormal operations. National Radiological Protection Board and Commissariat à l’Energie Atomique.
Document no. V/3865/79. Commission of the European Communities, Luxembourg, 1979.
Eckerman, K.F. and J.C. Ryman. External exposure to radionuclides in air, water, and soil. EPA-402-R93-081. Federal Guidance Report No. 12. U.S. Environmental Protection Agency, Washington, D.C.,
1993.
Emanuel, W.R., G.E.G. Killough and J.S. Olson. Modelling the circulation of carbon in the world’s
terrestrial ecosystems. pp.335-351 in: Carbon Cycle Modelling, Publication No. 1740. Environmental
Sciences Division, ORNL, 1981.
Hoffman, F.O., D.L. Shaeffer, C.W. Miller et al. Proceedings of a Workshop on the Evaluation ofModels Used for the Environmental Assessment of Radionuclide Releases. CONF-770901. Oak Ridge
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