DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCEICRP ref: 4834-8186-0460
5 July 2018

Annals of the ICRPICRP PUBLICATION 1XX

Dose Coefficients for External Exposures toEnvironmental Sources
Editor-in-Chief

C.H. CLEMENT
Associate Editor

H. FUJITA

Authors on behalf of ICRP
N. Petoussi-Henss, D. Satoh, A. Endo, K.F. Eckerman,
W.E. Bolch, J. Hunt, J.T.M. Jansen, C.H. Kim, C. Lee, K. Saito,
H. Schlattl, Y.S. Yeom, S.J. Yoo

PUBLISHED FOR
The International Commission on Radiological Protection
by[SAGE logo]
Please cite this issue as ‘ICRP, 20YY. Title of the annals. ICRP Publication XXX,
Ann. ICRP 00 (0).’1

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCECONTENTS[Guest] Editorial......................................................................................................................... 4
ABSTRACT 5
PREFACE
7
MAIN POINTS .......................................................................................................................... 8
EXECUTIVE SUMMARY ....................................................................................................... 9
GLOSSARY 11
1.
INTRODUCTION ........................................................................................... 18
2.
SCHEMA FOR DOSE ASSESSMENT FROM ENVIRONMENTALEXPOSURE 23
3.
DOSIMETRIC QUANTITIES USED IN RADIOLOGICAL PROTECTION
26
3.1.
Organ absorbed dose and equivalent dose ............................................................... 26
3.2.
Effective dose........................................................................................................... 27
3.3.
Air kerma ................................................................................................................. 28
3.4.
Operational quantities .............................................................................................. 28
4.
THE ICRP REFEENCE PHANTOM .............................................................. 30
4.1.
Adult reference computational phantoms ................................................................ 30
4.2.
The paediatric phantoms .......................................................................................... 31
5.
SIMULATION OF THE ENVIRONMENTAL RADIATION FIELD (STEP
1)
35
5.1.
Soil contamination ................................................................................................... 36
5.2.
Submersion to contaminated air............................................................................... 40
5.3.
Water immersion...................................................................................................... 42
5.4.
Calculation of air kerma and ambient dose equivalent in the environmental field . 43
6.
DETERMINATION OF DOSE RATE COEFFICIENTS FORMONOENERGETIC PARTICLES (STEP 2) ......................................................................... 47
6.1.
Monte Carlo photon and electron transport calculation in the anthropomorphic
phantoms .................................................................................................................................. 47
6.2.
Dose rate coefficients for soil contamination .......................................................... 48
6.3.
Dose rate coefficients for air submersion ................................................................ 60
6.4.
Dose rate coefficients for water immersion ............................................................. 64
6.5.
Verification of the calculations (spot-checks) ......................................................... 68
6.5.1.
GEANT4 (user Hanyang University) .............................................................. 69
6.5.2.
MCNP6 (user PHE) ......................................................................................... 69
6.5.3.
MCNPX (user KINS) ....................................................................................... 70
6.5.4.
MCNPX (user NCI) ......................................................................................... 70
6.5.5.
EGSnrc (user HMGU) ..................................................................................... 71
6.5.6.
Visible Monte Carlo (user IRD) ...................................................................... 71
6.5.7.
Comparison of dose rate coefficients calculated with different codes andcomparisons with other work ........................................................................................... 72
6.6.
Dose rate coefficients for monitoring - Air kerma and ambient dose equivalent rates.................................................................................................................................. 75
7.
EQUIVALENT AND EFFECTIVE DOSE RATE COEFFICIENTS FOR
RADIONUCLIDES (STEP3) .................................................................................................. 78
7.1.
Coefficients for equivalent dose rate to organs and tissues ..................................... 78
7.2.
Coefficients for effective dose rates ........................................................................ 78
7.3.
Coefficients for air kerma and ambient dose equivalent rate .................................. 792

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

8.
8.1.
soil

APPLICATION OF DOSE RATE COEFFICIENTS ..................................... 80
Application of dose rate coefficients to various depth profiles of radionuclides in.................................................................................................................................. 80
8.1.1.
Planar sources in specific depths ..................................................................... 80
8.1.2.
Volumetric sources .......................................................................................... 80
8.2.
Radionuclide decay chain ........................................................................................ 89
8.3.
Relationship between radioactivity in soil, effective dose, ambient dose equivalentand personal dose equivalent ..................................................................................................... 90
8.4.
Comparison with new operational quantities for external radiation proposed by
ICRU.................................................................................................................................. 91
8.5.
Application of dose rate coefficients for remediation planning............................... 92
9.
CONCLUSIONS.............................................................................................. 93
REFERENCES ........................................................................................................................ 95
ANNEX A. SKELETAL DOSIMETRY ........................................................................... 101
A.1.
References .............................................................................................................. 103
ANNEX B. SKIN DOSIMETRY ...................................................................................... 104
B.1.
Electron .................................................................................................................. 106
B.2.
Photons................................................................................................................... 109
B.3.
References .............................................................................................................. 112
ANNEX C. CONTENT OF THE ELECTRONIC SUPPLEMENT ................................. 114

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DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE[GUEST] EDITORIAL
To be drafted

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ABSTRACT

Dose Coefficients for External Exposures toEnvironmental Sources
ICRP Publication XXXApproved by the Commission in xxx
Abstract- This publication presents radionuclide-specific organ and effective dose rate
coefficients for members of the public resulting from environmental external exposures toradionuclide emissions of both photons and electrons, calculated using computational
phantoms representing the ICRP reference newborn, 1-year-old, 5-year-old, 10-year-old, 15year-old, and adult males and females. Environmental radiation fields of monoenergetic
photon and electron sources were firstly computed using the Monte Carlo radiation transport
code PHITS (Particle and Heavy Ion Transport code System) for source geometries
representing environmental radionuclide exposures including planar sources on and within
the ground at different depths (representing radionuclide ground contamination from fall-out
or naturally occurring terrestrial sources), volumetric sources in air (representing aradioactive cloud), and uniformly distributed sources in simulated contaminated water. For
the above geometries, the exposed reference individual is considered to be completely within
the radiation field. Organ equivalent dose rate coefficients for monoenergetic photons andelectrons were next computed employing the PHITS code thus simulating photon andelectron interactions within the tissues and organs of the exposed reference individual. For
quality assurance purposes, further cross-check calculations were performed using GEANT4,
EGSnrc, MCNPX, MCNP6, and the Visible Monte Carlo radiation transport codes. From themonoenergetic values, nuclide-specific effective and organ equivalent dose rate coefficientsfor several radionuclides for the above environmental exposures were computed using thenuclear decay data from Publication 107. The coefficients are given as dose rates normalised
to radionuclide concentrations in environmental media, such as radioactivity concentration, inunits of nSv h-1 Bq-1 m-2 or nSv h-1 Bq-1 m-3 and can be re-normalised to ambient dose
equivalent (Sv Sv-1) or air kerma (Sv Gy-1). The findings showed that, in general, the smaller
the body mass of the phantom, the higher the organ and effective dose due to (1) closer
proximity to the source (in the case of ground contamination) and (2) the smaller amount ofbody shielding of internal organs in the younger and smaller reference phantoms. The
difference in effective dose between an adult and an infant is 60-140% at a photon energy of
50 keV, while it is less than 70% above a photon energy of 100 keV, where the smallerdifferences are observed for air submersion and the largest differences are observed for soil
contamination on the surface of the ground. For realistic exposure situations of radionuclide
environmental contamination, the difference was found to be more moderate. For example,
for radioactive caesium (134Cs, 136Cs, 137Cs/137mBa) deposited on and in the ground, thedifference in effective dose between an adult and an infant was in the range of 20-60%,
depending on the radioactivity deposition depth within the soil.

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DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE© 20YY ICRP. Published by SAGE.
Keywords: External radiation; Environmental; Effective Dose; Organ equivalent dose; Dose
coefficients; Ambient dose equivalent; Soil contamination; Air submersion; Water
immersion.
AUTHORS ON BEHALF OF ICRP
N. Petoussi-Henss, D. Satoh, A. Endo, K.F. Eckerman,
W.E. Bolch, J. Hunt, J.T.M. Jansen, C.H. Kim, C. Lee,
K. Saito, H. Schlattl, Y.S. Yeom, S.J. Yoo

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DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

PREFACEThe membership of the Task Group 90 “Age Dependent Dose Coefficients for External
Environmental Exposures” was as follows:
N. Petoussi-Henss (Chair)
W. Bolch

K. Eckerman
A. EndoH. Schlattl

Corresponding members were:
M. Bellamy
N. Hertel
J. Hunt

J.T.M. Jansen
C. LeeK. Saito

D. Satoh
Y. S. Yeom
S. J. Yoo

Additional contributor to this publication was:D. Santos
The membership of Committee 2 during the period of preparation of this report was:(2009-2013)
H-G. Menzel (Chair)
M.R. Bailey
M. Balonov
D. Bartlett
V. Berkovski
W.E. Bolch

R. CoxG. Dietze
K.F. Eckerman
A. EndoJ.D. Harrison
N. Ishigure

R. Leggett
J.L. Lipsztein
J. Ma
F. Paquet
N. Petoussi-Henss
A.S. Pradhan(2013-2017)
J.D. Harrison (Chair)
M.R. Bailey
V. Berkovski
L. Bertelli
W.E. Bolch
D. Chambers

M. Degteva
A. EndoJ.G. Hunt
C. Hyeong Kim
R. Leggett
J. Ma

D. Noβke
F. Paquet
N. Petoussi-Henss
F. Wissmann(2017-2020)
J.D. Harrison (Chair)
V. Berkovski
E. Blanchardon
W.E. Bolch
A. Giussani
D. JokischC. Hyeong Kim
R. Leggett
J. Li
M.A. Lopez
F. Paquet
N. Petoussi-Henss

T. SatoT. Smith
A. Ulanowski
F. Wissmann

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MAIN POINTS













This publication presents radionuclide-specific reference organ and effective dose
rate coefficients for the following types of environmental external exposures: soil
contamination, air submersion, and water immersion.
These coefficients are needed to evaluate effective dose and/or organ equivalentdoses from activity concentrations in the environment, air kerma free in air,absorbed dose in air, or ambient dose equivalent.
Calculation of the coefficients requires modelling of the environmental field
including the exposure geometry, density and composition of both soil and air, andspatial distribution of the radionuclide contamination. The most probable exposure
scenarios for both chronic/routine and accidental releases were identified and theserespective environmental radiation fields were simulated with the Monte Carloradiation transport code PHITS.
The magnitude of organ equivalent doses from environmental radionuclide
exposures depend on body size since, in external exposures, increasing amounts ofoverlying tissue enhance body shielding of internal organs. Accordingly, the fullseries of ICRP reference individuals – both male and female – were considered inthis report, including computational phantoms of the newborn, 1-year-old, 5-yearold, 10-year-old, 15-year-old, and adult.
The types of radiation considered were monoenergetic photons (initial energies
between 0.01 and 8 MeV) and monoenergetic electrons (same energy range). Thesesimulation results were later used to model organ dosimetry for environmental
emissions of gamma-rays, conversion electrons, characteristic x-rays, Auger
electrons, and bremsstrahlung x-rays.
The organ and effective dose rate coefficients tabulated in this report are given
normalised to environmental radioactivity concentrations for 1252 radionuclides
whose nuclear decay data (energies, yields, and branching ratios) are provided in
Publication 107.
The main text of the report provides effective dose rate coefficients for the reference
person at each reference age, with additional information on organ equivalent dose
rate coefficients provided in an electronic supplement to this report.
The ambient dose equivalent and air kerma rates were obtained for both soil
contamination and air submersion using Monte Carlo simulations for theenvironmental geometries considered. These data enable interpretation ofmonitoring data relating effective doses to measured values of ambient dose
equivalent or air kerma.

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41
42

EXECUTIVE SUMMARY

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(a) External irradiation from environmental sources of radionuclides is an important
pathway of exposure to members of the public which may result from both routine discharges
and major accidental releases from nuclear facilities, regions of high naturally occurring
radionuclide soil concentrations, or environmental contamination following radiologicalterrorist events. In the early stages following a nuclear accident, internal exposures due toboth inhalation and ingestion of radionuclides are likely to contribute significantly to organ
and effective doses, within additional exposure from radionuclide decays in contaminated air
plumes, all of which depend upon a variety of factors based upon regional weather
conditions. Both external and internal exposures to the public are important after a nuclear
accident, whereas external exposures are the more significant exposure pathway over longer
timeframes. This was particularly the case following the nuclear power plant (NPP) accident
in Fukushima Prefecture, Japan in March of 2011 (UNSCEAR, 2013). Radionuclide
ingestion can also play an important role after a certain time following nuclear facility
accidents, if appropriate restrictions are not performed promptly regarding the distribution
and consumption of potentially contaminated foodstuffs.
(b) Age-dependent dose coefficients for the internal exposures have been evaluatedcomprehensively by ICRP in Publications 56, 67, 69, 71, and 72 (ICRP, 1990, 1993, 1995a,c,
1996a), with current updates published for the reference adults under the Occupational
Intakes of Radionuclide (OIR) series (ICRP, 2015, 2016b, 2017). However, age-dependent
dose coefficients for external environmental exposures have not been previously evaluated by
ICRP. These data are especially important for dose evaluation in the environment whereindividuals across a wide range of age groups can be potentially exposed. The purpose of thisreport is, therefore, to provide reference age-dependent dose rate coefficients for external
environmental exposures for members of the general public.
(c) Dose rate coefficients are needed to evaluate effective dose from measured or evaluateddata on environmental radioactivity concentrations, air kerma rates, absorbed dose rates inair, or ambient dose equivalent rates. Calculation of dose rate coefficients requires evaluationof the environmental field (such as the exposure geometry, the density and composition ofsoil, and the radionuclide concentration distribution in the environmental media), anatomic
computational models of the human body (such as reference voxel phantoms representing
exposed members of the general public), and transport simulations of emitted radiations
within both the environmental media and anatomy of the exposed individuals. Organ
equivalent doses depend on body size since, in external photon exposures, increasing
amounts of overlying tissue (skeletal muscle and subcutaneous fats in particular) enhance theshielding of deeper radiosensitive organs (ICRP, 2010). Resultantly, this publicationconsiders the full range of ICRP reference individuals (newborn to adults) in thesecalculations.
(d) The Task Group has identified the most probable exposure scenarios for thispublication. These scenarios are exposure to contamination on or below the ground surface
and at different depths (ground exposure); submersion in a contaminated atmospheric cloud(air submersion); and immersion in contaminated water (water immersion). In the first two
scenarios, air-over-ground geometry and a human body standing up-right above the groundwere assumed.

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(e) Organ and effective dose rate coefficients for environmental exposures were computedfor the ICRP voxel-based adult male and female reference computational phantoms in
Publication 110 (ICRP, 2009a) as well as for the 10 ICRP reference paediatric phantoms
which are a voxel format of the polygon mesh/NURBS (non-rational B-spline) surface
phantoms of the University of Florida and National Cancer Institute (Lee et al., 2010). The
latter, following some modifications, have been selected in 2013 to become the reference
ICRP paediatric phantoms.
(f) ICRP establishes for the first time reference dose rate coefficients for exposure toenvironmental radionuclides in air, soil and water. Radiations considered include direct
photons from radionuclide decays, scattered photons in the environment, beta particles andelectrons and bremsstrahlung x-rays from beta particles and from conversion and Auger
electrons. For contaminated soil and air, computations were performed in three steps. In Step
1, radiation transport of monoenergetic particles (photons and electrons) from thecontaminated environment was conducted and with the resulting radiation field (particle type,energy, and direction) recorded to the surface of a virtual cylinder surrounding the exposed
individual (a so-called coupling cylinder). In Step 2, the recorded particles on the surface ofthe coupling cylinder were subsequently transported, in turn, within the body of each of the
12 reference phantoms. In Step 3, values of organ equivalent dose rate for monoenergetic
particles were spectrum weighted to yield radionuclide-specific dose rate coefficients.
Additional simulations under the Step 2 included the placement of an air sphere for tallying
ambient dose equivalent rate and air kerma rate at a height of 1 m from the ground surface so
as to report organ and effective dose rate coefficients normalised to either the environmental
radionuclide concentration, or measured values of ambient dose equivalent rate or air kerma
rate, where the latter might be obtained from radiation environmental monitoring data.
(g) A data viewer code is provided which allows comfortable viewing and downloading of
the dose rate coefficient data.

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GLOSSARY

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Absorbed dose, D
The absorbed dose is given by
dε
dm

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D=

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where d ε is the mean energy imparted by ionising radiation to matter of mass (dm).
The unit of absorbed dose is joule per kilogramme (J kg-1), and its special name isgray (Gy).

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125
126

Active (bone) marrow
Active marrow is haematopoietically active and gets its red colour from the large
numbers of erythrocytes (red blood cells) being produced. Active bone marrow serves
as a target tissue for radiogenic risk of leukaemia.

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128
129
130

Activity
The number of nuclear transformations of a radioactive material during an
infinitesimal time interval, divided by its duration (s). The SI unit of activity is thebecquerel (Bq; 1 Bq = 1 s-1).

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Activity concentration
Concentration of radioactivity per unit volume per of air or water. The SI unit ofactivity concentration is Bq m-3.

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Activity areal concentration
Concentration of radioactivity per unit area of soil. The SI unit of activity areal
concentration is Bq m-2.

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Activity density
The activity of a specified radionuclide per unit mass, volume or area of a specified
substance.

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Air submersion or submersion to contaminated airExternal exposure from radionuclides in the radioactive cloud or plume.

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Ambient dose equivalent, H*(10)The dose equivalent at a point in a radiation field that would be produced by thecorresponding expanded and aligned field in the ICRU sphere at depth of 10 mm on
the radius opposing the direction of the aligned field. The unit of ambient dose
equivalent is joule per kilogramme (J kg-1) and its special name is sievert (Sv).

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Ambient dose equivalent rate coefficient, ℎ̇(10)11DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

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The coefficient to convert the activity concentration to the ambient dose equivalentrate. The unit of the ambient dose equivalent rate coefficient for the environmental
exposures as referred in this report is nSv h-1 Bq-1 m3 or nSv h-1 Bq-1 m2.

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Becquerel
The special name for the SI unit of activity. 1 Bq = 1 s-1, 1 MBq =106 Bq.

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Bone marrow
Bone marrow is a soft, highly cellular tissue that occupies the cylindrical cavities oflong bones and the cavities defined by the bone trabeculae of the axial andappendicular skeleton. Total bone marrow consists of a sponge-like, reticular,
connective tissue framework called stroma, myeloid (blood-cell-forming) tissue, fatcells (adipocytes), small accumulations of lymphatic tissue, and numerous bloodvessels and sinusoids. There are two types of bone marrow, red (or active) and yellow(inactive). See ‘Active (bone) marrow’; ‘Inactive (bone) marrow’.

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Bone Surfaces
See ‘Endosteum’.

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Charged-Particle Equilibrium
Charged-particle equilibrium in a volume of interest means that the energies,
numbers, and directions of the charged particles are constant throughout this volume.
This is equivalent to saying that the distribution of charged-particle energy radiancedoes not vary within the volume. In particular, it follows that the sums of the energies(excluding rest energies) of the charged particles entering and leaving the volume are
equal.

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Cross section,σThe cross section of a target entity, for a particular interaction produced by incident
charged or uncharged particles of a given type and energy, is given by

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N
Φ
where N is the mean number of such interactions per target entity subjected to theparticle fluence (Φ). The unit of cross section is m2. A special unit often used for the
cross section is the barn where 1 barn (b) = 10-28 m2. A full description of aninteraction process requires, ‘inter alia’, the knowledge of the distributions of crosssections in terms of energy and direction of all emergent particles from theinteraction. Such distributions, sometimes called ‘differential cross sections’, areobtained by differentiations of σ with respect to energy and solid angle.

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Deposition density
Activity of a specified radionuclide per unit ground area integrated into depth
direction, resulted from fallout. The unit is Bq m-2.

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Deterministic effectSee ‘Tissue reaction’.

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σ =

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Dose coefficient
A coefficient relating a dose quantity to a physical quantity, both for internal andexternal radiation exposure. For external environmental exposures, the quantities
activity concentration, ambient dose equivalent or air kerma are chosen.

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Dose rate coefficient
A coefficient relating a dose quantity to a physical quantity, both for internal andexternal radiation exposure per unit time.

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Dose equivalent, H
The dose equivalent at a point is given by

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H = QD
where D is the absorbed dose and Q is the quality factor at that point. The unit of dose
equivalent is joule per kilogramme (J kg−1), and its special name is sievert (Sv).

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Dose equivalent rate, ℎ̇Dose equivalent per unit time.

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Dose response function, DRF
A particular function used in this publication to represent the absorbed dose in atarget region per particle fluence in that region, derived using models of the
microscopic structure of the target region geometry, and the transport of thesecondary ionising radiations in those regions.

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Effective dose, E
The tissue-weighted sum of equivalent doses in all specified organs and tissues of thebody, given by the expression

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E = ∑ wT ∑ wR DT,R = ∑ wT H T
T

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R

T

where HT is the equivalent dose in an organ or tissue T, DT,R the mean absorbed dosein an organ or tissue T from radiation of type R, and wT is the tissue weighting factor.
The sum is performed over all organs and tissues of the human body considered to besensitive to the induction of stochastic effects. The SI unit for effective dose is joule
per kilogramme (J kg-1), and its special name is sievert (Sv).

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Effective dose rate coefficient, 𝑒𝑒̇Effective dose per unit time.

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Endosteum (or endosteal layer)
A 50-μm-thick layer covering the surfaces of the bone trabeculae in regions oftrabecular spongiosa and those of the cortical surfaces of the medullary cavities
within the shafts of all long bones. It is assumed to be the target region for radiogenic
bone cancer. This target region replaces that previously introduced in Publications 26
and 30 – the bone surfaces – which had been defined as a single-cell layer, 10 μm inthickness, covering the surfaces of both the bone trabeculae and the Haversian canals
of cortical bone.
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Equivalent dose, HT
The equivalent dose in an organ or tissue T is given by:
H T = ∑ wR DT, R
R

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where DT,R is the mean absorbed dose from radiation R in an organ or tissue T, andwR is the radiation weighting factor. The unit for equivalent dose is joule perkilogramme (J kg-1) and its special name is sievert (Sv).

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Equivalent dose rate coefficient, ℎ̇T
Equivalent dose per unit time.

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Fluence, ΦThe quotient of dN by da, where dN is the number of particles incident on a sphere ofcross-sectional area da, thus:

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dN
da
The unit of fluence is m-2.

Φ=

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ICRU 4-element tissue
ICRU 4-element tissue like material with density of 1 g cm-3, and a masscomposition: 76.2 % oxygen, 11.1 % carbon, 10.1 % hydrogen and 2.6 % nitrogen.
The ICRU sphere has this assumed composition.

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Inactive (bone) marrow
In contrast to the active marrow, inactive marrow is haematopoietically inactive (i.e.,does not support haematopoiesis directly). It gets its yellow colour from fat cells(adipocytes) that occupy most of the space of the yellow bone marrow framework.

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Kerma (K)
Quantity for uncharged ionising particles, defined by the quotient of dEtr by dm,
where dEtr is the mean sum of the initial kinetic energies of all the charged particles
liberated in a mass (dm) of a material by the uncharged particles incident on dm, thus:
K=

dE tr
dm

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The unit for kerma is joule per kilogramme (J kg-1) and its special name is gray (Gy).

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Kerma approximation
Kerma is sometimes used as an approximation to the absorbed dose. The numericalvalue of the kerma approaches that of the absorbed dose to the degree that chargedparticle equilibrium exists, that radiative losses are negligible, and that the kinetic
energy of the uncharged particles is large, compared to the binding energy of theliberated charged particles.

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Marrow cellularity

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The fraction of bone marrow volume in a given bone that is haematopoietically
active. Age- and bone-site-dependent reference values for marrow cellularity are
given in Table 41 of Publication 70 (ICRP, 1995b). As a first approximation, marrowcellularity may be thought of as 1 minus the fat fraction of bone marrow.
Mean absorbed dose in an organ or tissue, DT
The mean absorbed dose in a specified organ or tissue T, is given by264

DT = 1/mT ∫ D dm,

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where mT is the mass of the organ or tissue, and D is the absorbed dose in the masselement (dm). The SI unit of mean absorbed dose is joule per kilogramme (J kg-1),
and its special name is gray (Gy).

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Mean free path (mfp)
The average distance travelled by a particle without suffering a collision.

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Operational quantities
Quantities used in practical applications for monitoring and investigating situations
involving external exposure and intakes of radionuclides. They are defined formeasurements and assessment of doses in the body.

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Organ absorbed dose
Short phrase for ‘mean absorbed dose in an organ or tissue’.

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Organ equivalent dose
Short phrase for ‘equivalent dose in an organ or tissue’.

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Physical half life
The period of time for one-half of the atoms of a radionuclide to disintegrate.

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Protection quantities
Dose quantities related to the human body that ICRP has developed for radiologicalprotection to allow quantification of the detriment to people from exposure to ionisingradiation from both whole and partial body external irradiation and from intakes ofradionuclides.

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Quality factor, Q
The quality factor at a point in tissue, is given by
∞

287

1
Q=
Q( L) DL dL
D L∫= 0

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291

where D is the absorbed dose at that point, DL is the distribution of D in unrestricted
linear energy transfer L at the point of interest, and Q(L) is the quality factor asfunction of L. The integration is to be performed over DL, due to all charged particles,
excluding their secondary electrons.

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Radiation weighting factor, wR

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A dimensionless factor by which the organ or tissue absorbed dose is multiplied toreflect the higher biological effectiveness of high-linear energy transfer (LET)
radiations compared with low-LET radiations. It is used to derive the equivalent dosefrom the absorbed dose averaged over an organ or tissue.

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298

Red (bone) marrow
See ‘Active (bone) marrow’.

299
300
301
302

Reference Male and Reference Female (Reference Individual)
An idealised male or female with characteristics defined by ICRP for the purpose ofradiological protection, and with the anatomical and physiological characteristics
defined in Publication 89 (ICRP, 2002).

303
304
305
306
307

Reference Person
An idealised person, for whom the equivalent doses to organs and tissues arecalculated by averaging the corresponding doses of the Reference Male and theReference Female. The equivalent doses of the Reference Person are used for the
calculation of effective dose.

308
309
310
311

Reference phantom
The computational phantom of the human body (male or female voxel phantom basedon medical imaging data), defined in Publication 110 (ICRP, 2009a) with anatomicaland physiological characteristics defined in Publication 89 (ICRP, 2002).

312
313
314
315

Reference value
Value of a quantity recommended by ICRP for use in dosimetric applications or
biokinetic models. Reference values are fixed and specified with no uncertainty,
independent of the fact that the basis of these values includes many uncertainties.

316
317
318
319
320
321
322

Relaxation mass per unit area
Activity concentrations in soil in many instances are described by a depth-dependant
exponential function of the form A = exp(-z/β) where A is the activity concentration, zis the soil depth, and β is a parameter called the relaxation mass per unit area. The
magnitude of beta is an indication of the radionuclide penetration in the soil withlarge values of β indicating a steeper exponential distribution. The unit of relaxation
mass per unit area is g cm-2.

323
324

Response function
See ‘Dose response function’.

325
326

Soil contamination, ground source
A source describing deposited radionuclides on the surface and in the soil.

327
328
329
330
331

Spongiosa
Term referring to the combined tissues of the bone trabeculae and marrow tissues(both active and inactive) located beneath cortical bone cortices across regions of theaxial and appendicular skeleton. Spongiosa is one of three bone regions defined in the
Publication 110 (ICRP, 2009a) reference phantoms, the other two being cortical bone

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333
334
335

and medullary marrow of the long bone shafts. As the relative proportions oftrabecular bone, active marrow, and inactive marrow vary with skeletal site, thehomogeneous elemental composition and mass density of spongiosa are not constantbut vary with skeletal site [see Annex B of Publication 110 (ICRP, 2009a)].

336
337
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339
340

Tissue reaction
Injury in populations of cells, characterised by a threshold dose and an increase in theseverity of the reaction as the dose is increased further. Tissue reactions are also
termed ‘deterministic effect’. In some cases, these effects are modifiable by postirradiation procedures including biological response modifiers.

341
342
343
344

Tissue weighting factor, wTA factor by which the equivalent dose in an organ or tissue T is weighted to represent
the relative contribution of that organ or tissue to the total health detriment resulting
from uniform irradiation of the body (ICRP, 1991). It is defined such that:345∑ w = 1.
T

T

346
347
348
349
350

Voxel phantom
Computational anthropomorphic phantom based on medical tomographic images inwhich the anatomy is described by small three-dimensional volume elements(voxels). Collections of these voxels are used to specify the organs and tissues of thehuman body.

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352

Yellow (bone) marrow
See ‘Inactive (bone) marrow’.

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354

Water immersion
External exposure from radionuclides in the radioactive water.

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356

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1. INTRODUCTION

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(1) In the environment, the public is exposed to various external radiation sources such as
naturally occurring radionuclides in soil and other environmental media, as well as cosmic
radiation originating from solar particle events and galactic cosmic rays. Moreover, small
quantities of radionuclides are discharged from nuclear facilities into the environment underroutine operations, leading to small but constant exposures to the public. In the case of amajor nuclear facility accidents, potentially large quantities of radionuclides could be released
into the environment, resulting in wide geographic regions of contamination. Such was thecase following the nuclear power plant (NPP) accidents in Chernobyl, Ukraine in 1987 and in
Fukushima Prefecture, Japan in 2011. Both resulted in exposures to members of the generalpublic, with the former being substantially more significant than the latter. In such cases,
accurate evaluation of radiation doses to the exposed public is essential to estimate the impactof the accident and to take appropriate radiological protection measures.
(2) External exposure to environmental sources is an important pathway of exposure of
the public after major releases of radionuclides to the environment. In the early stage after anuclear accident, internal exposures due to inhalation and ingestion of radionuclides are likely
to significantly contribute to organ equivalent and effective dose, together with external dose
contributions from submersion within the radioactive cloud or plume, depending on manyfactors, such as the regional weather conditions. However, sometime after an accidental
release, and if appropriate restrictions of foodstuffs based on reliable measurements are
implemented, external exposures become the dominant contributor to the radiation dose tomembers of the public. As shown in Fig.1.1, this was specifically the case following theaccident at the nuclear power plant in Fukushima Prefecture in 2011.
(3) Age-dependent dose coefficients for internal exposures have been evaluatedcomprehensively by ICRP in Publications 56, 67, 69, 71, and 72 (ICRP, 1990, 1993, 1995a,c,
1996a), with recent revisions for adult exposures released as part of the OIR (Occupational
Intakes of Radionuclides) (ICRP, 2015, 2016b, 2017). However, to date, reference values ofage-dependent dose coefficients for external environmental exposures have not been
evaluated by ICRP. In this publication, environmental radionuclide external exposures to thefull range of ICRP reference individuals is addressed, as age-dependent dose rate coefficientsare essential in dose evaluations from environmental exposures.

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415
416

Fig. 1.1 Estimated district-averaged effective doses to adults, children and infants, living inFukushima city (from UNSCEAR (2013)).
(4) The current ICRP system of radiological protection uses a generalised, gender and age
averaged set of tissue and radiation weighting factors to convert organ absorbed dose to organ
equivalent dose and then to the effective dose, E. While doses incurred at low levels of
exposure may be measured or assessed with reasonable accuracy, the associated risks are
uncertain. However, bearing in mind the uncertainties associated with risk projection to low
doses, it is considered reasonable to use E as an approximate indicator of possible risk, withthe additional consideration of variations in risk with age, sex, and population group (ICRP
publication on Effective Dose, in preparation). E, according to Publication 103 (ICRP, 2007),is calculated for sex-averaged Reference Persons at specified ages. Publication 103 definition
includes the specification of reference male and female anatomical models for radiationtransport calculations. While exposures may relate to individuals or population groups, E iscalculated for Reference Persons exposed in the same way.
(5) Organ equivalent doses depend on body size, and so dose rate coefficients for the
adult are not adequate for the assessment of doses to children. However, tissue weighting
factors and radiation weighting factors are approximate values determined by judgment basedon in-vivo and other radiobiology or radiation epidemiological studies.
(6) For external exposures to environmental sources, the dosimetric quantities of interest
are the radiation doses received by the radiosensitive organs and tissues of the body due tophotons and electrons emitted by radionuclides distributed in soil, air or water. The types ofradiation considered are those of importance for external exposure by radionuclides: photons
including bremsstrahlung and electrons including beta particles. The neutron dose fromradionuclides released to the environment after a nuclear accident is considered to be
negligible. Also, neutrons as well as muons from cosmic radiation are not dealt with in thispublication. If there is a need to estimate doses from cosmic radiation the reader is referred tothe study by Sato (2016).

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(7) The geographic pattern of radionuclide distribution in air or soil is dependent on timeand duration of release, deposition pathways, the chemical form of released radionuclides,
and on prevailing meteorological conditions at the time of the release. The latter can include
the wind direction and any rainfall or snowfall occurring during the passage of the plume. Fora routine or extended release, wind direction can be expected to vary over time. In the longer
term, rainfall, snowfall, and weathering will allow penetration of deposited radionuclides into
soil and some migration via water pathways or through resuspension. The deposition densities
of released radionuclides are often quite heterogeneous. Generally in the longer term, one or a
few radionuclides will dominate as the principal contributors to human exposure (such as
137
Cs and 134Cs as in the case of the Fukushima NPP accident) (UNSCEAR, 2008, 2013;
ICRP, 2009b; Saito et al., 2015).
(8) Soil contamination is the most important source in large-scale accidents since depositedradionuclides continue to expose member of the general public over wide geographicalregions for long time periods (UNSCEAR, 2008, 2013; Mikami et al., 2015; Saito et al.,2015). Deposited radionuclides in the ground with respect to depth (via leaching) may be
represented sometime after the accident by an exponentially decreasing concentration profile
from the soil surface; moreover, the so-called relaxation mass per unit area (in units of g cm2), is an indicator of radionuclide migration into the ground and is observed to increase withelapsed time since initial soil deposition (ICRU, 1994; Matsuda et al., 2015). Further, thedeposited radionuclides could have various concentration profiles – mostly exponential or
profiles exhibiting a peak at a certain soil depth that can be approximated by a hyperbolic
secant function (Matsuda et al., 2015). Since it is not possible to simulate all possible soildepth distributions, simulations for planar sources at fixed depths below the ground surface
can provide the basic data to enable the reconstruction of diverse and complex radionuclide
sources with different depth profiles. A similar approach was employed by Eckerman and
Ryman (1993) and by the ICRU (1994) where dose rate coefficients for planar sources wereconvoluted to approximate any specific or desired radionuclide concentration soil depth
profile.
(9) Similarly, the source conditions following a radioactive release in air could change invarious ways according to the prevailing and time-dependent meteorological conditions. Near
the release point, the radionuclide concentrations in air are often modelled by Gaussian
distributions perpendicular to the wind axis (Gaussian plume model), and typical metrologicalconditions are classified into several categories due to atmospheric turbulence conditions andtemperature-altitude profiles. The degree of radionuclide dispersion could be entirely different
according to these meteorological conditions; therefore, the relation of dose rates attributed toradionuclide concentrations and their distributions in air can vary greatly. Consequently, it is
not practical to evaluate dose rate coefficients to cover all possible diverse conditions. At
locations sufficiently far from the release point, the radionuclide distributions in air could beapproximated to be uniform and the hemispherical submersion model is considered to be agood approximation at all exposure locations due to the rapid homogenisation of theradioactive material in air.
(10) Water immersion might be rare in the pathway of environmental exposure; however,radioactive releases to the oceans and seas, or the contamination of surface waters have been
observed following major radiological accidents. In a large accident, aquatic systems such as
rivers, ponds, and seas might be contaminated, and inhabitants might be immersed in watercontaining radionuclides. Generally, it is anticipated that exposure from water immersion is
not significant in most cases, but in order to be able to evaluate such exposures, dose rate
coefficients for water immersion are also needed.

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(11) A number of publications have reported dose rate coefficients for external irradiationof the body for monoenergetic sources or for radionuclides distributed in the environment(Dillman, 1974; Poston and Snyder, 1974; O' Brien and Sanna, 1976; DOE, 1988; Petoussi etal., 1989, 1991; Jacob et al., 1990; Saito et al., 1990, 1991, 1998; Eckerman and Ryman,
1993; Zankl et al., 2002; Petoussi-Henss and Saito, 2009). Most of the above publications are
based on mathematical computational phantoms, mainly of adults. Data on organ equivalentdoses for external exposures to the newborn and children are scarce. The first calculated data
based on voxel computational phantoms stemmed from work published in Saito et al. (1990),
Jacob et al (1990) and Petoussi et al. (1991), who computed the dose rate coefficients for ababy of 8 weeks of age and for a 7-year-old child.
(12) After 2011, many research studies re-visited these calculations using current and morestate-of-the-art Monte Carlo methods and anatomic phantoms. An update of the work of Saito
et al. (1990) and Jacob et al (1990) can be found in Petoussi-Henss et al. (2012). Saito et al.
(2012) estimated effective dose rate coefficients, assuming an exponential distribution ofradioactivity in the ground and over a wide range of depths for both adults and the newborn.
Yoo et al (2013a,b) presented nuclide-specific dose rate coefficients for air submersion,
ground surface contamination, and water immersion exposure situations for the ICRP adultreference phantoms. Satoh et al (2015) presented dose rate coefficients for exposure to both134
Cs and 137Cs for different age-groups using both the ICRP adult reference phantoms and the
University of Florida paediatric NURBS-based computational phantoms. Bellamy et al (2016)
employed age-specific mathematical phantoms for calculations of effective dose rates forsubmersion in radioactive air, and for water immersion. Veinot et al (2017) computed thesevalues for the same phantoms following exposure to contaminated soil.
(13) The purpose of the present report is, therefore, to provide ICRP reference agedependent dose rate coefficients for external exposures to environmentally present
radionuclides as needed for both prospective and retrospective radiological protection
assessment to exposed populations of children and adults. Experience from post-accident
situations suggests that there is broad public concern that children are more at risk fromradiation exposure than adults, and that the protection of children in particular is of highimportance to the population, and consequently, for radiological protection. The variability oforgan equivalent dose with gender, body size, and age has been demonstrated byinvestigations covering various types of external exposures (Zankl et al., 2002; Johnson et al.,2009; Cassola et al., 2011; Petoussi-Henss et al., 2012; Lv et al., 2017).
(14) Today the main method for assessment of absorbed doses in the human body fromexternal radiation fields is by the application of Monte Carlo radiation transport methods. The
simulation results are then expressed in terms of organ equivalent dose rate coefficientsgiving the organ equivalent dose rate per unit of environmental activity concentration, or
external dose rate measurement. Hereafter in this publication, they will be referred to as dose
rate coefficients, or simply as coefficients.
(15) For simulating the exposure to fields of environmental radiation, the following three
typical cases of environmental sources have been addressed in this report: (1) soil (ground)contamination, simulated as fully infinite planar sources on the ground surface and at selected
depths below the ground surface; (2) air submersion, simulated as a semi-infinite volume
source of radionuclides in air; and (3) water immersion, simulated as a fully infinite
radionuclide source in water. The dose rate coefficients have been computed for the ICRP
voxel-based adult male and female reference computational phantoms (ICRP, 2009a) as well
as for the 10 paediatric NURBS-based phantoms of the University of Florida/National Cancer
Institute series (Lee et al., 2010). The latter are voxelized computational phantoms and have21

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523
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531
532
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537
538
539
540
541
542
543
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546

been selected, following specific modifications, to become the reference ICRP paediatricphantoms (Bolch et al., 2016; Chang et al., 2017).
(16) Computations performed for soil contamination and submersion to contaminated air
were carried out in three distinct steps: Step 1 involves radiation transport of monoenergetic
particles from the contaminated environment (soil or air) to a virtual cylinder surrounding theexposed individual subsequently referred to as the ‘coupling cylinder’; Step 2 involves
transport of the primary and secondary radiation particles recorded on the surface of thecoupling cylinder into the phantom; Step 3 entails spectrum weighting of the resultant organ
equivalent doses to yield radionuclide-specific dose rate coefficients. Additional simulations
under Step 2 include the placing of an air sphere for tallying air kerma and ambient dose
equivalent rates at a height of 1 m above the ground surface. This additional step is needed inorder to report organ and effective dose rate coefficients both in terms of environmental
radionuclide concentration, but also in terms of these measured quantities. Separation of Steps
1 and 2 significantly improves the calculation efficiency and statistical accuracy of thecomputed results, because the same radiation fields recorded at the coupling cylinder can be
repeatedly used for different exposed computational phantoms. For water immersion, theorgan equivalent dose rate coefficients for monoenergetic particles were computed directly,
without the use of the coupling cylinder.
(17) The expected applications of the dose rate coefficients are: (a) pre-accidental
evaluations in order to predict the possible impacts to the public by postulated radiologicalaccidents, (b) post-accidental evaluations to estimate doses in order to develop a radiologicalprotection strategy for the exposed populace, (c) evaluations following discharge ofradionuclides from nuclear and radioisotope facilities during routine operations, and (d)evaluations of naturally occurring radionuclides in the environment. The pre/post-accident
analyses are performed typically by software packages (e.g. codes for severe accidents). The
software predicts the dispersion, migration, and distribution of radionuclides in theenvironment. The dose rate coefficients of the present publication can thus be implemented inthese codes.
(18) It should be noted that dose rate coefficients are calculated for idealised andhypothetical source geometries such as semi-infinite and uniform distributions, for reference
phantoms wearing no clothing, and for an idealised, upright postures, even for the exposed
newborn. As a result, they do not fully reflect actual exposures for a particular situation andexposed individual.

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547
548

2. SCHEMA FOR DOSE ASSESSMENT FROM ENVIRONMENTALEXPOSURE

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(19) Dose rate coefficients are needed to evaluate effective dose from measurable
quantities such as radioactivity concentrations (i.e., surface activity density and air activity
density), air kerma rate, absorbed dose rates in air, or ambient dose equivalent rates. These
quantities are mostly obtained from environmental measurements but also from evaluation
using computational models or computer simulations. Calculation of dose rate coefficientsrequires the evaluation of the environmental field (i.e., exposure geometry, density andcomposition of soil and air, and radionuclide concentration depth profiles), anatomic modelsof the human body (i.e., reference phantoms for various members of the general public), andthe simulation of the radiation transport through the environment and into the body of the
exposed individual. Organ equivalent doses depend on body size since, in external exposures,increasing amounts of overlying muscle and adipose tissue enhances the shielding of deeper
seated radiosensitive organs (ICRP, 2010). Furthermore, the characteristics of radiation fields
change with height above ground soon after the deposition, especially for sources on and in
the ground, and thus the body height, and extension the differing locations of radiosensitive
internal organs, can impact the magnitude of assessed organ equivalent dose. For example, inthe early stages after the accident in Fukushima nuclear power plant, it was reported that thedose rate in air at 0.5 m height was higher than that at 1 m, which caused many concerns
regarding the reliable evaluation of exposures to children.
(20) Fig. 2.1. shows a schematic representation of the evaluation of organ equivalent andeffective dose rates in the environment. The measurable quantities used mostly for theevaluation of exposures in the environment are the radionuclide concentration in the soil, air,or water, and the dose rates in air at 1 m height. To evaluate organ equivalent dose rates or
effective dose rates from these quantities, dose (rate) coefficients are necessary. Generally,
there are three methods for dose assessment for external environmental exposures, as shownin Fig. 2.1.
(21) The first method (DC1 in Fig. 2.1) is the direct conversion from radionuclide
concentration in the environmental media such as soil, air, and water. The radionuclide
concentrations, expressed in units of Bq kg-1 or Bq m-3, are usually determined by collection
and analyses of environmental samples of these environmental media. In case of soil
contamination, deposition density per unit area (Bq m-2) is often used because this quantity
indicates the contamination level of a location regardless of radionuclide depth profile.
Alternatively, in situ measurements using a portable Ge semiconductor detectors are
sometimes performed (Mikami et al., 2015). Furthermore, computer modelling could be used
to determine the radionuclide concentrations in the environment. For example, simulations of
air dispersion enable the analysis of the movement of radionuclides within the environment,
and thus provide predicted values of radionuclide concentrations in air and on the ground. For
evaluating the exposure, these data need to be related to the effective dose rates or organ
equivalent dose rates experienced by exposed individuals located within the vicinity of where
the modelled or measured radionuclide environmental concentration is present.
(22) The second method (DC2 in Fig. 2.2) is employing conversions based uponmeasurement of dose rates in air. Historically, dose rates in air have been measured in termsof air kerma rate or air absorbed dose rate (both in units of Gy h-1). After the introduction of
the operational quantity ambient dose equivalent, the ambient dose equivalent rate (in Sv h-1)
was also applied to environmental radiation monitoring and has been widely used. An
enormous amount of air dose rate data has been accumulated in terms of Gy h-1 and Sv h-1,
and these data are converted to effective dose and equivalent dose rates with dose rate
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623
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630

coefficients expressed in units of Sv Gy-1 or Sv Sv-1. UNSCEAR (2013) has used the value of
0.7 for conversion from air absorbed dose (Gy) to effective dose (Sv). This is considered to bea representative value for adults; however, this value could change according to the source
distribution, energy spectrum and age of exposed individual. For example, this value isobviously lower for low energy photon sources. It must be noted that ambient dose equivalentneeds also to be converted to effective dose for appropriate dose evaluations in theenvironment even though the units are the same (i.e. Sv h-1). After the radiological accident in
the Fukushima NPP, ambient dose equivalent was often erroneously regarded to be equal toeffective dose without the application of any dose rate coefficients, and this resultantly led tooverestimation of exposure doses to members of the public.
(23) The third method (DC3 and then DC2) demonstrated in Fig. 2.1 is employed when theestimation of dose rates in air (i.e. absorbed dose rates in Gy h-1 and ambient equivalent dose
rates in Sv h-1) is necessary in addition to the estimation of effective dose and equivalent dose
rates (Sv h-1). From a viewpoint of environmental radiation monitoring, the measured dose
rate in air at 1 m height is a very important quantity and can be compared with the value
calculated using method DC3. To calculate the effective or equivalent dose a two-step
approach, DC3 followed by DC2, can be used. First, the radionuclide concentration in theenvironment (Bq m-2 or Bq m-3) is converted to dose rate in air at 1 m height using DC3 andthen the dose rate in air can be converted to effective dose and equivalent dose rate with DC2.
In principle, the effective dose and equivalent dose rates obtained by the two-step method
provide similar values to those which would have been obtained directly using DC1 given thesame initial conditions.
(24) If the source conditions are not typical and DC3 cannot provide reliable estimation ofdose rates in air, and if direct measurements are difficult, a modified two-step approach could
be applied. First, dose rates are evaluated taking into account the specific conditions of thecontamination situation, then the evaluated air dose rates are converted to effective dose andequivalent dose rates using DC2. This approach was used after the Fukushima NPP accident,
for cases where the deposition density per unit area and depth profile of radionuclides
deposited on the ground varied significantly with location, especially if decontamination was
performed. In such complex contamination conditions, dose rates in air in terms of ambient
equivalent dose rate are evaluated, taking into account precisely the horizontal and vertical
distribution of radioactive caesium, as performed by Malins et al. (2016) who aimed atinvestigating the efficiency of decontamination work postulating different decontamination
methods and extents. The dose rate in air obtained in this way could be further converted into
effective dose or equivalent dose rates by applying DC2, which is an approach less sensitive
to source distribution.

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631
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Fig. 2.1. Schematic representation of evaluation of effective and organ equivalent dose rates
in the environment. DC1-DC3 indicate the different methods of dose evaluation, as explained
in section 2.

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3. DOSIMETRIC QUANTITIES USED IN RADIOLOGICALPROTECTION

639

3.1. Organ absorbed dose and equivalent dose

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641
642
643
644

(25) The mean absorbed dose averaged over the volume of organs and tissues is theprimary scientific quantity from which effective dose, E, is calculated. Absorbed dose (D) isdefined as the quotient of mean energy dε , imparted by ionising radiation in a volume
element and the mass, dm, of the matter in that volume:
D=

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dε
dm

(3.1)

(26) The SI unit of absorbed dose is J kg-1 and its special name is gray (Gy). Absorbed doseis derived from the mean value of the stochastic quantity of energy imparted, ε, and does notreflect the random fluctuations of the interaction events in tissue. While it is defined at any
point in matter, its value is obtained as an average over a mass element dm and hence overmany atoms or molecules of matter.
(27) When using the quantity absorbed dose in radiological protection, doses are averaged
over tissue volumes. It is assumed that for low doses, the mean value of absorbed dose
averaged over a specific organ or tissue can be correlated with radiation detriment forstochastic effects in that tissue with an accuracy sufficient for the purposes of radiologicalprotection. The averaging of absorbed dose is carried out over the volume of a specified organ(e.g. liver) or tissue (e.g. active bone marrow) or the sensitive region of a tissue (e.g.
endosteal surfaces of the skeleton). Absorbed dose D is used to set limits on organ/tissue
doses to prevent tissue reactions (deterministic effects).
(28) Equivalent dose, HT to a tissue or organ is defined as:
H T = ∑ wR DT, R

(3.2)

R

663
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670

where wR is the radiation weighting factor for radiation type R, and DT,R is the organ absorbed
dose from radiation type R in a tissue or organ T of the age-specified Reference Male or
Female. Since wR is dimensionless, the SI unit for the equivalent dose is the same as forabsorbed dose, J kg-1, and its special name is sievert (Sv). Values of wR are shown in Table
3.1 and are taken from Publication 103 (ICRP, 2007).
Table 3.1. ICRP radiation weighting factors.
Radiation Type
Radiation Weighting Factor, wR
Photons
Electrons and muonsProtons and charged pions
Alpha particles, fission
heavy ions
Neutrons

fragments,

1
1
2
20
Continuous function of neutron energy
See Eqn. 4.3 of Publication 103

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671

3.2. Effective dose

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675

(29) The effective dose, E, introduced in Publication 60 (ICRP, 1991) is the risk-related
quantity in radiation protection and is defined as a weighted sum of tissue equivalent doses. In
accordance with the definition of effective dose in Publication 103 (ICRP, 2007), theeffective dose is computed as:

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693

694
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705
706
707
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709
710

𝐻𝐻 𝑀𝑀 +𝐻𝐻 𝐹𝐹

𝐸𝐸 = ∑ 𝑤𝑤𝑇𝑇 � 𝑇𝑇 2 𝑇𝑇 �

(3.3)

where 𝐻𝐻𝑇𝑇𝑀𝑀 and 𝐻𝐻𝑇𝑇𝐹𝐹 are the equivalent doses to the tissues or organs T of the Reference Maleand Female, respectively, and wT is the tissue weighting factor for target tissue T, with ΣwT =1. The sum is performed over all organs and tissues of the human body considered to besensitive to the induction of stochastic effects. Values of wT are given in Table 3.2. (ICRP,
2007). Since wR and wT are dimensionless, the SI unit for effective dose is the same as forabsorbed dose, J kg-1, and its special name is Sievert (Sv).
(30) Effective dose (E) was originally introduced for the control of occupational exposures
to external and internal sources of radiation. While the concept has remained essentiallyunchanged through Publication 60 (ICRP, 1991) to Publication 103 (ICRP, 2007), its use has
been extended to members of the public of all ages, including in utero exposures of the foetus(ICRP, 2001, 2004, 2006).
(31) ICRP provides effective dose coefficients for situations of external and internal
exposures of workers and members of the public, and for radiopharmaceutical administrations
to patients, as reference values for use in prospective and retrospective dose assessments.
Table 3.2. ICRP tissue weighting factors (ICRP, 2007).
TissueBone-marrow, breast, colon, lung, stomach,remainder tissues (13*)
GonadsUrinary bladder, oesophagus, liver, thyroid
Bone surface, brain, salivary glands, skin

wT
0.12

∑ wT
0.72

0.08
0.04
0.01

0.08
0.16
0.04

*Remainder tissues: adrenals, extrathoracic (ET) regions of the respiratory tract, gall bladder,heart, kidneys, lymphatic nodes, muscle, oral mucosa, pancreas, prostate (male), small
intestine, spleen, thymus, uterus/cervix (female).
(32) E is calculated for sex-averaged Reference Persons at specified ages as defined in
Publication 89. The Publication 103 definition includes the specification of reference maleand female anatomical models for radiation transport calculations. While exposures may
relate to individuals or population groups, E is calculated for Reference Persons exposed in
the same way.
(33) Effective dose (E), in units of sievert (Sv), is accepted internationally as the central
radiological protection quantity and is used for regulatory purposes worldwide, providing arisk-adjusted measure of total body dose from both external and internal sources in relation tostochastic risks of cancer and hereditary effects, expressed in terms of detriment. It has proved
to be a valuable and robust quantity for use in the optimisation of protection and in setting ofcontrol criteria such as dose limits, constraints and reference levels. In its general application,effective dose does not provide an individual-specific dose but it rather applies to a reference27

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

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712

person under the same exposure situation. As such, the effective dose cannot be used for theassessment of individual risk (ICRP, 2007).

713

3.3. Air kerma

714
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722
723
724
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727

(34) For measuring external radiation, basic physical quantities that relate the radioactivity
in the environment with the protection and the operational quantities are required. National
and international standards laboratories maintain standards and reference radiation fields thatare specified and described in terms of these quantities for calibration of instruments anddosimeters. Air kerma free-in-air, 𝐾𝐾air , has been used for this purpose (ICRU, 1994, 2014;
ICRP, 1996b). In further text throughout this publication, the quantity air kerma free-in-air isusually referred to simply as ‘air kerma’.
(35) The kerma, 𝐾𝐾, for ionising uncharged particles, is given byd𝐸𝐸
𝐾𝐾 = d𝑚𝑚tr(3.4)
where d𝐸𝐸tr is the mean sum of the initial kinetic energies of all the charged particles liberated
in the mass (d𝑚𝑚) of a material by the uncharged particles incident on d𝑚𝑚. The unit of kerma
is J kg-1, and has the special name gray (Gy). The quantity (d𝐸𝐸tr ) includes the kinetic energyof the charged particles emitted in the decay of excited atoms/molecules or in nuclear deexcitation or disintegration.

728

3.4. Operational quantities

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(36) The protection quantities ‘organ equivalent dose’ and ‘effective dose’ are notmeasurable, and therefore cannot be used directly as quantities in radiation monitoring.
Operational quantities are thus used for the assessment of the protection quantities (effective
dose, or equivalent dose in tissues or organs). The operational quantities aim to provide a
reasonable estimate of the values of protection quantities relevant to the exposure of humans
to external radiations under most irradiation conditions (ICRU, 1985, 1988, 1993).
(37) The operational quantities are defined using the quantity dose equivalent, 𝐻𝐻 (ICRU,
1985). 𝐻𝐻 is the product of 𝑄𝑄 and 𝐷𝐷 at a point in tissue; thus, 𝐻𝐻 = 𝑄𝑄𝑄𝑄 , where 𝐷𝐷 is theabsorbed dose and 𝑄𝑄 is the quality factor at that point. 𝑄𝑄 is defined as a function ofunrestricted linear energy transfer (𝐿𝐿∞ , often denoted as 𝐿𝐿 or LET) of charged particles inwater (ICRP, 1996b).
(38) For area monitoring, two quantities, namely, the ambient dose equivalent, 𝐻𝐻 ∗ (𝑑𝑑), andthe directional dose equivalent, 𝐻𝐻 ′ (𝑑𝑑, 𝜴𝜴), are used to link external radiations to the effective
dose and to the equivalent dose in the lens of the eye and local skin. 𝐻𝐻 ∗ (𝑑𝑑), at a point in aradiation field, is the dose equivalent that would be produced by the corresponding expanded
and aligned field, in the ICRU sphere at a depth (𝑑𝑑), on the radius opposing the direction of
the aligned field. 𝐻𝐻 ′ (𝑑𝑑, 𝜴𝜴), at a point in a radiation field, is the dose equivalent that would be
produced by the corresponding expanded field, in the ICRU sphere at a depth (𝑑𝑑) on a radius
in a specified direction (𝜴𝜴).
(39) For individual monitoring, the personal dose equivalent, 𝐻𝐻p (𝑑𝑑), is used. 𝐻𝐻p (𝑑𝑑) is thedose equivalent in soft tissue, at an appropriate depth, 𝑑𝑑, below a specified point on the body.
The specified point is usually given by the position where the individual’s dosimeter is worn.
(40) The recommended values of 𝑑𝑑 are chosen for the assessment of various doses: 𝑑𝑑 =10mm for effective dose, 𝑑𝑑 = 3 mm for dose to the eye lens, and 𝑑𝑑 = 0.07 mm for dose to the28DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

753
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755

skin and to the hands and feet. The unit of ambient dose equivalent, directional dose
equivalent, and personal dose equivalent is J kg-1, and has the special name sievert (Sv).

29

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756

4. THE ICRP REFEENCE PHANTOM

757

4.1. Adult reference computational phantoms

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(41) Computational phantoms of the human body – together with radiation transport codes– have been employed for many years in the evaluation of organ equivalent dose rate
coefficients in environmental radiation protection. During the last two decades, voxel
phantoms were introduced that are derived mostly from (whole body) medical image data ofreal persons instead of the older mathematical MIRD-type body models. A voxel model (orphantom) is a three-dimensional representation of the human body in the form of an array ofidentification numbers, arranged in slices, rows, and columns. Each entry in this array
represents a tissue voxel; organs are then represented by those voxels having the same
identification number and are spatially arranged to represent the organ volume. Moreinformation on voxel phantoms, their development and use can be found elsewhere (Xu andEckerman, 2010).
(42) For the computation of organ absorbed doses, the adult male and female referencecomputational phantoms, representing the ICRP Reference Adult Male and Reference Adult
Female (ICRP, 2007) were used in this report. These phantoms were adopted by ICRP and
ICRU as the phantoms for the computation of the ICRP reference dose coefficients and areextensively described in Publication 110 (ICRP, 2009a). The reference computational
phantoms are based on human computed tomographic (CT) data and were constructed bymodifying the voxel models (Zankl and Wittmann, 2001; Zankl et al., 2005) of two
individuals (Golem and Laura) whose body height and mass closely resembled the reference
data. The organ masses of both phantoms were adjusted to the ICRP data given in Publication
89 (ICRP, 2002) on the Reference Male and Reference Female with high precision, without
significantly altering their realistic anatomy. The phantoms contain all target regions relevantto the assessment of human exposure to ionising radiation for radiological protection
purposes, including all tissues and organs that contribute to the protection quantity effective
dose (ICRP, 2007).
(43) The male reference computational phantom consists of approximately 1.95 million
tissue voxels (excluding voxels representing the surrounding vacuum) each with a slice
thickness (corresponding to the voxel height) of 8.0 mm and an in-plane resolution (i.e. voxel
width and depth) of 2.137 mm, corresponding to a voxel volume of 36.54 mm3. The numberof slices is 220, resulting in a body height of 1.76 m and total body mass of 73 kg. The female
reference computational phantom consists of approximately 3.89 million tissue voxels, eachwith a slice thickness of 4.84 mm and an in-plane resolution of 1.775 mm, corresponding to avoxel volume of 15.25 mm3. The number of slices is 346, and thus the body height is 1.63 m
and the total body mass is 60 kg. The number of individually segmented structures is 136 ineach phantom, and 53 different tissue compositions have been assigned to them. The various
tissue compositions reflect both the elemental composition of the tissue parenchyma (ICRU,
1992) and each organ’s blood content (ICRP, 2002) (i.e. organ composition inclusive ofblood). Fig. 4.1 shows frontal (coronal) views of the male (right) and female (left)
computational phantom, respectively.
(44) Due to the limited resolution of the source tomographic data upon which thesephantoms were constructed, and the very small dimensions of some of the ICRP definedsource and target regions, not all tissues could be explicitly represented. In the skeleton, forexample, the target tissues of interest are the haematopoietically active bone marrow locatedwithin the marrow cavities of spongiosa, as well as the endosteal layer lining the surfaces of30

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

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the bone trabeculae and the inner surfaces of the medullary cavities of the long bones(presently assumed to be 50 μm in thickness). Due to their small dimensions, these two target
tissues had to be incorporated as homogeneous constituents of spongiosa within the reference
phantoms. At lower energies of photon and neutrons, secondary charged-particle equilibrium
is not fully established in these tissue regions over certain energy ranges. Consequently, morerefined techniques for accounting for these effects in skeletal dosimetry were used in thisreport, and are discussed more fully within Annex A.

810
811
812
813
814

Fig. 4.1. Images of the adult male (right) and adult female (left) computational phantoms(ICRP, 2009a). The following organs can be identified by different surface colours: breast,colon, eyes, lungs, liver, pancreas, salivary glands, small intestine, stomach, thyroid andurinary bladder, testes, teeth. Muscle and adipose tissue are semi-transparent.

815

4.2. The paediatric phantoms

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(45) The series of ten ICRP paediatric computational phantoms are the following:
Newborn – Male and Female
1-year-old – Male and Female
5-year-old – Male and Female
10-year-old – Male and Female
15-year-old – Male and Female(46) These phantoms were derived from a series of computational phantoms developed
originally at the University of Florida (UF) and later in collaboration with the National Cancer
Institute (NCI). Consequently, the original phantoms from which the ICRP paediatricphantoms were derived are presently referred to as the UF/NCI phantom series (Lee et al.,2010). The UF/NCI phantoms are of a third generation of phantom technology – hybrid
phantoms – in which the outer body contour and internal organ surfaces are modelled using
the computer animation techniques of either polygon mesh or NURBS (Non-Uniform






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829
830
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876

Rational B-Spline) surfaces depending on the complexity of anatomical structures. The
polygon meshes are a cluster of adjacent triangles, while the NURBS surfaces are a cluster of
3D points in space between which a surface is interpolated. Within the past few years,
computational phantoms in these two formats can be directly used in some Monte Carlotransport codes as necessary. However, most transport codes still utilise a voxel format,
composed of tiny cuboidal prisms. A computer script was thus used to convert the UF/NCI
hybrid phantoms from their surface format to a voxel format for Monte Carlo simulations
conducted in the current Publication. These ICRP reference paediatric phantoms in voxel
format are thus consistent with the format of the ICRP Publication 110 reference adultphantoms (ICRP, 2009a).
(47) As noted in Lee et al. (2010), the UF/NCI series of phantoms are traceable directly toreal human anatomy. The newborn phantom is based upon full-body CT imaging of a 6-day
female cadaver, while the remainder of the paediatric series (1-year-old to 15-year-old
phantoms) are based upon combinations of head CT images, full torso CT images, andrescaled CT-based images of adult arms and legs. The latter approach was necessary since
medical imaging of children rarely include the arms within the imaging field. From the initialseries of segmented images, various anatomic sources were used to resize both internal organ
anatomy and exterior body size. The most important document used was Publication 89(ICRP, 2002) providing internal organ masses, and values of total weight and height.
Additional reference sources were used to target various body circumferential dimensions not
given as reference values in Publication 89. The final series of the UF/NCI hybrid phantoms
thus fully conforms to reference anatomy specified by the Commission and are fully traceable
to real human CT anatomy. In this manner, the ICRP paediatric phantom series is fullycompatible with the process used to develop the Publication 110 phantoms, which also werebased upon segmentation of real human CT anatomy.
(48) Another unique feature of the ICRP paediatric phantoms (and of the UF/NCI
phantoms), is their explicit coupling to microCT based models of skeletal dosimetry. As notedin Hough et al. (2011) and in Johnson et al. (2011), an extensive series of cadaver bone
harvests, ex-vivo skeletal CT imaging, and ex-vivo spongiosa core microCT imaging, wereused to construct models of tissue dosimetry in the skeletons of the ICRP reference adultphantoms. This work is more formally described Annexes D and E of Publication 116 (ICRP,
2010). The paediatric series of ICRP reference phantoms similarly have accompanying
models of skeletal anatomy at both its macrostructural and microstructural dimensions. Thus,
the methods proposed in Publication 116 (ICRP, 2010) for external photons and neutrons, andin Publication 133 (ICRP, 2016a) for internal beta and alpha particles, as well as photons, for
the ICRP Publication 110 adult phantoms, are available in reporting skeletal tissue dosimetry
to paediatric members of the reference series.
(49) The following further refinements have been made to the UF/NCI series of paediatricphantoms (Pafundi, 2009; Wayson, 2012):
 A sub-segmented skeletal model to include regions of cortical bone, spongiosa, andmedullary marrow Photon dose response functions for internal and external photon dosimetry to active
marrow and endosteum New age-specific regional blood distribution model (Wayson, 2012) Corresponding model of the major blood vessels
 Separation of subcutaneous fat and skeletal muscle from what was formally residual soft
tissues (RST) Inclusion of lymphatic nodes - see Lee et al. (2013)32

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884
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902

(50) The series of ICRP paediatric reference phantoms are in voxel format, and fully
conform to the framework established in Publication 110 (ICRP, 2009a). All organs andtissue structures modelled in the ICRP Publication 110 reference adult male and female
phantoms are included in the series of ICRP paediatric phantoms with consistent ID numbers(see Annex A of Publication 110). Representative images of the ICRP paediatric series are
given in Fig. 4.2.

Fig. 4.2. Series of ICRP reference paediatric phantoms. The male and female newborn, 1-, 5and 10-year-old phantoms are anatomically identical, except for their gonads.
(51) While the ICRP paediatric reference phantoms are identical in format to the ICRP
Publication 110 (ICRP, 2009a) adult phantoms regarding the ID numbers of the various
source and target organs, one important difference is the voxel resolution. One of the main
advantages of hybrid phantom technology is that in the conversion of the polygon
mesh/NURBS format of the phantom to the voxel format of that same anatomy, one can selectthe voxel resolution. Table 4.1 tabulates the voxel resolutions, array size, and total matrix size
finally adopted for the ICRP paediatric phantoms. These ensure continuous conformance withthe 1% matching of reference masses as well as conform to reference total skin thickness asgiven by data in Publication 89. It is noted that for the newborn phantom, the voxels are cubic(i.e., same thickness in x, y, and z directions), while rectangular prisms with larger zdimension than xy-dimensions were adopted for the older phantoms so as to keep the matrix
size constant at 55 million voxels in total. In contrast, the ICRP Publication 110 adult maleand female phantoms have total matrix sizes of 1.9 and 3.9 million voxels, respectively. The
need for higher resolution is to preserve organ anatomy in the smaller anatomy of thepaediatric reference individuals.

33

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

903
904
905
906

Table 4.1. Voxel resolution, voxel number, and total matrix size of the ICRP paediatriccomputational phantom series.
Resolution (cm)Phantom
Newborn Female
Newborn Male
1 –Year Female
1 –Year Male
5 –Year Female
5 –Year Male
10 –Year Female
10 –Year Male
15 –Year Female
15 –Year MaleX
0.06630.06630.06630.06630.08500.08500.09900.09900.12000.1250Y
0.06630.06630.06630.06630.08500.08500.09900.09900.12000.1250Z
0.06630.06630.14000.14000.19280.19280.24250.24250.28280.2832

907
908

34

Array size
X
350
350
396
396
424
424
432
432
408
416

Y
215
215
253
253
235
235
226
226
242
230

Z
720
720
550
550
576
576
580
580
574
590

Matrixsize(million)
54.2
54.2
55.1
55.1
57.4
57.4
56.6
56.6
56.7
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DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

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910

5. SIMULATION OF THE ENVIRONMENTAL RADIATION FIELD(STEP 1)

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(52) Photons emitted from sources distributed in the environment are scattered and/or
absorbed in both air and soil, and their energy spectrum and angular distribution in air havespecific features dependent on the initial energy and spatial distribution of the emission sites.
In the case of volumetric sources in air or ground, the angular distribution of incident photons
is nearly uniform for the hemisphere from which the source originates, while small amountsof scattered photons emerge from the opposing semi-sphere (Saito et al., 1998). In case of
deposited sources in the ground, the dominant component of photons is incident alonghorizontal directions. Monte Carlo method is a suitable tool able to simulate the particle
transport and the detailed environmental conditions.
(53) For simulating the exposure to environmental radiation, the following three typicalcases of environmental sources have been addressed in this report: (1) soil (ground)contamination, simulated as fully infinite planar sources on the surface and at different depths
in the ground; (2) air submersion, simulated as a semi-infinite volume source in air; and (3)water immersion, simulated as a fully infinite source in water. The first source simulates thedeposition of radionuclides on and below the ground surface, by assuming an infinite planarsource on the surface and in the soil. The second source configuration models the gaseousradioactive release into the atmosphere at locations which are not too near to the release point,
by assuming a homogeneous contamination of the air in a semi-spherical region above asmooth air-ground interface of radius whose dimension depends on the mean free path of thephotons of interest. The third source simulates immersion in uniformly contaminated water.
For the first and second source configurations, the human body is assumed to be standing upright on the ground, while for water exposures, the human body is assumed to be fully
immersed.
(54) The transport of radiation particles in the environment was simulated using the Monte
Carlo simulation package Particle and Heavy Ion Transport code System (PHITS) (Sato et al.,2013). PHITS is a multi-purpose Monte Carlo code that simulates the transport andinteraction of hadrons, leptons, and heavy ions in arbitrary three-dimensional geometries.
Version 2.66 of the PHITS code was used in this report (Sato et al., 2013). For simulating
photon and electron transport, respectively, the atomic data libraries MCPLIB04 (White,2003) and EL03 (Adams, 2000) were employed. These libraries provide precise cross-section
data and can treat various physical processes of both photons and electrons.
(55) PHITS defines the geometry of the calculation model in terms of the combinatorial
geometry (CG) and the general geometry (GG). In addition, a capability for describing
repeated structures and lattice geometries is available to define three-dimensional voxel
phantoms. PHITS has a function to draw 2-dimensional and 3-dimensional figures of thecalculation geometries as well as the computed data results using a graphic package ANGEL(Niita et al., 2010).
(56) In the environmental radiation transport simulation for photon sources, only photons
were transported and secondary electrons generated by photon interactions were not followed.
This is because the secondary electrons lose their energies continuously and stop within ashort distance in the environmental media. However, bremsstrahlung photons generated bysecondary electrons have maximum energies comparable to those of the secondary electrons
and are able to propagate across long distances. The production of the bremsstrahlung
photons, and their energy and emission angle were sampled at the interaction point based on a
thick-target bremsstrahlung approximation model (MCNP, 2003). For electron sources, boththe primary electrons and their secondary photons were transported in the environment.
35

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(57) As previously mentioned, the radiation field computed due to monoenergetic radiation
emissions from within the contaminated air and soil was expressed as the position, angle ofincidence, and energy of the particles incident on the surface of a virtual cylinder of 2 mheight and 0.6 m diameter, which surrounds the exposed individual, and is termed thecoupling cylinder. As the phantom was not present in this first step, the same coupling
cylinder source could be applied for all phantoms. Saito et al (1990) had previously examined
the perturbation of the photon fields on the human body and found it to be insignificant under
the conditions considered above. Fig. 5.1 shows schematically which particles were recordedon the surface of the coupling cylinder.

968
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971
972
973
974

(58) To cover the wide energy range of radiations that are emitted by many different
radionuclides, the monoenergetic photon and electron energies considered were varied from0.01 to 8 MeV.

975

5.1. Soil contamination

976
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979
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981
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983
984
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986
987
988

(59) Soon after deposition, radionuclides deposited on the ground are assumed to form aplanar source at the ground surface. Over time, these radionuclides will migrate or leach into
the soil thereby developing diverse concentration depth profiles in terms of both shape anddegree of soil penetration (Matsuda et al., 2015). In many cases, the distribution ofradionuclides with respect to soil depth could be approximated as being due to many infinite
planar sources within the ground. These functions could have various characteristics, showing
peaks at different depths in the soil. Since it is not practical to simulate every radionuclide/soil
migration function, the simulation of a series of planar radiation sources at different depths
can provide basic data enabling one to extrapolate or interpolate these results to model diverse
source profiles within the contaminated ground.
(60) The air-over-ground geometry was modelled such as air bounds on the ground with an
infinite flat surface. In the real environment, the terrain is not normally flat nor infinite;
however, the infinite flat terrain could well represent most real situations for dose evaluation.

Fig. 5.1. Schematic representation of particle transport during Step 1 and Step 2 of thecalculation.

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990
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992
993
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996
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998
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1000
1001
1002
1003
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1005
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1007
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1009
1010
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1013
1014
1015
1016
1017
1018
1019
1020
1021
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1025
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For example, in case of an exponentially distributed ground source with a relaxation mass perarea of 1 g cm-2, which is a typical depth observed soon after radionuclide ground deposition,
approximately half of the measured ambient dose equivalent at 1 m height is attributed tophotons from sources within a radius of 5 m in the ground (Malins et al., 2016). Thus, alimited series of flat ground surface areas is considered to adequately model the exposure formany real exposure situations.
(61) The monoenergetic radioactive sources were defined as planar sources at depths in soil
expressed in terms of mean free paths (mfp) of photons in soil: 0.0 (i.e. the contamination is
on the surface), 0.2, 1, 2.5 and 4 mfp. For most exposure situations, the consideration of mean
free paths up to 4 would be sufficient (Eckerman and Ryman, 1993); however, the source
depth profile might be changed, due to, for example, ploughing. Thus, dose rate coefficientsfor a wider range of mean free paths would be useful and had been therefore considered tofacilitate an accurate integration when determining dose rate coefficients for continuous
source-depth profiles. The air-ground interface (0 mm) is a flat planar source without any soil
covering the source. This is an idealised geometry and does not exist in reality, as there is avariety of factors that provide shielding from ground surface sources. These include thepresence of vegetation, surface roughness, and particle movement due to gravitational forces(Burson and Profio, 1977; Kocher and Sjoreen, 1985; Jacob and Paretzke, 1986).
Furthermore, the depth of 0.5 g cm-2 was considered, as representative of the surface
roughness and initial migration following precipitation. It simulates the deposition ofradionuclides in the ground the first years after migration (ICRU, 1994). This source depth isconsistent with earlier work by Saito et al. (1990) and Petoussi et al. (1991) and with therecent work of Petoussi-Henss et al. (2012), Yoo et al. (2013a), Bellamy et al. (2018). It has
been also shown previously that for a 137Cs/137mBa source distributed as a planar source at a
depth of 0.5 g cm-2, the air kerma in air is reduced by a factor of 0.67, compared to a purely
surface planar source on the ground (UNSCEAR, 2016). Therefore, in the present report, dose
rate coefficients for contaminated ground planes are presented for surface contamination,
contamination at depths expressed as mfp, as described before, as well as for a planar source
at depth of 0.5 g cm-2 which is equivalent to 3 mm of soil with density of 1.6 × 103 kg m-3
representing the ground roughness.
(62) Fig. 5.2 (left) shows schematically the simulation geometry, which consists of a rightcircular cylinder constructed from a layer of air with a height of 3 mfp and of soil with adepth depending on the photon energy: 2 mfp of photons in soil for source depth 0.0 mfp and
0.2 mfp; 3 mfp for source depth of 1.0 mfp; 3.5 mfp for source depth of 2.5 mfp; 5 mfp forsource depth of 4.0 mfp. The additional thickness of at least 1 mfp below the source depth
was considered sufficient to account for backscatter events in the deeper layers. The radius of
the cylinder corresponds to about five times the mean free path of the relevant photons in air.
A previous study (Satoh et al., 2014) has shown that this size of simulation geometry is
sufficient to properly treat photon transport in the contaminated environment.

37

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047

Fig. 5.2. Schematic representation of the geometry simulating the environmental field due tosoil contamination, mfp: mean free path.
(63) Table 5.1 lists the density and elemental composition of air and soil adopted in thecomputations of this report. The values were obtained from the data for soil (Type 1) provided
by the International Commission on Radiation Units & Measurements (ICRU) (ICRU, 1994)
and dry air from the National Institute of Standards and Technology (NIST) (Berger et al.,2005), respectively. The densities of soil and air were considered to be 1 g cm-3 and 1.2x10-3 g
cm-3, respectively. In real environmental exposure situations, the soil densities are mostly
higher than 1×103 kg m-3 and could vary according to both location and depth; however, thisvariation does not affect the relation of source intensity to the radiation field in air, if source
depth is expressed in terms of g cm-2. Furthermore, it has been shown that changes in soil
composition do not significantly alter the transported photon fields at the phantom coupling
surface (Saito and Jacob, 1995).
Table 5.1. Density and elemental composition of air (Berger et al., 2005) and soil (ICRU,
1994).
Density
Elemental composition (wt%)
Material g cm-3
Air
1.2x10-3
Soil
1.0

1048
1049
1050
1051
1052
1053
1054
1055

H
2.20

C
1.24x10

-

-2

N
75.53
-

O
23.18
57.50

Al
8.50

Si
26.20

Ar
1.28
-

Fe
5.60

(64) The radiation field was derived for 25 initial photon energies, ranging from 0.01 to 8
MeV, so as to cover the wide energy spectra of natural occurring and artificially produced
radionuclides. The soil was assumed as a planar air-ground interface and scatter andabsorption of the radiation fields in both air and ground were considered in the calculations.
(65) Electron planar sources were also considered for the surface of the soil; for otherdepths, primary electron sources were not transported since they will not travel sufficiently far
to reach the surface. Initial electron energies from 0.01 to 8 MeV were considered. For

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DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094

electron sources, both electrons and secondary photons were transported. It should be notedthat bremsstrahlung x-rays were considered in both the soil and air exposure scenarios.
(66) From the transport calculations in the environment, individual particles were recordedat the surface of a virtual cylinder termed the ‘coupling cylinder’. This cylinder is positionedon the ground concentric with the simulation geometry, as depicted in Fig. 5.2 (right). The
diameter of the cylinder is 0.6 m, and its height is 2 m. The phase-space coordinates arerecorded for particles that cross the surface of the cylinder and consists of the spatial
coordinates (x, y, x), momentum (px, py, pz), kinetic energy, and Monte Carlo weight. In order
to avoid counting a particle as it exits the cylinder, the space inside the coupling cylinder istreated as an ideal absorber such that the Monte Carlo code terminates the transport of theparticle when it enters this region. The data were recorded to an external file in ASCII format
to be used for the Step 2 calculations - organ equivalent dose calculations within thephantoms. The small fraction of those photons that could be scattered back into the cylinderfrom the ground or air, is followed in Step 2 calculations (i.e., particles starting from thesurface of coupling cylinder). More details on the method can be found in Satoh et al. (2015).
(67) To reduce the variance of the Monte Carlo simulations, the uniform source was
reproduced by increasing the number of radioactive decays per unit area and decreasing theMonte Carlo weight of particles released by radioactive decay as its emission point
approaches the coupling cylinder (Satoh et al., 2015).
(68) Fig. 5.3 shows an example of the energy and angular distribution of environmental
photons from a source of 0.5 MeV at a depth of 0.2 mfp, at heights 0 - 0.40 m and 1.60 - 2.00
m, as this is recorded on the surface of the coupling cylinder. The incident directions ofphotons are expressed as the sine of a vector parallel to the ground surface and the angles are
expressed as elevation angles. It can be seen, that, quite a large portion of the photons comesfrom the direction of 30° upwards and the majority of photons are between 0 and 30° withrespect to the horizontal plane. Consequently, they exhibit a rather pronounced horizontal
bias.
(69) Uncollided photons are recorded in the highest energy bin. Overall, about 20% of therecorded photons on the coupling cylinder never interact with the air. It should be noted thatthe shape of the energy and angular spectra are rather independent of height.
(70) The directional distributions of scattered and uncollided photons for a source of 0.1
MeV at 1 and 4 mfp depths in the ground, respectively, are shown in Fig. 5.4. The scatteredphotons show a small local maximum at shallow directions downwards, which is more
pronounced for 1 mfp than for 4 mfp. This is in agreement with the angular dependence of air
kerma for sources at 1 and 4 mfp, respectively, as reported by Eckerman and Ryman (1993).
The relative number of uncollided photons is considerably decreased from about 22% at 1
mfp to about 7% at 4 mfp.

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1095
1096
1097
1098
1099
1100
1101

Fig. 5.3. Energy (left) and angular (right) distribution of an isotropic infinite source in the soil
at a depth of 0.2 mfp, emitting 0.5 MeV monoenergetic photons. (left) The y axis shows thenumber of photons per energy bin (right). The y axis shows the number of photons per sine
angle at the indicated height range. To differentiate these distributions from the respective
distribution for all heights (Φ), they are marked by the superscript j.

1102
1103
1104
1105
1106
1107

Fig. 5.4. Angular distribution of scattered and uncollided photons for an isotropic infinite
source in the soil at a depth of 1 mfp (left) and 4 mfp (right) emitting 0.1 MeV monoenergetic
photons. The y axis shows the number of photons per sine angle. To differentiate these
distributions from the respective total distribution (Φ), they are marked by the superscript j.

1108

5.2. Submersion to contaminated air

1109
1110
1111
1112
1113
1114
1115
1116
1117

(71) In the air submersion exposure scenario, the contaminated air represents the gaseousradioactive release into the atmosphere at locations which are not too near to the release point,
and are assumed to be homogeneous in air activity concentration above a smooth air-groundinterface. Near the release point, radionuclides in air distribute according to the Gaussian
plume model, and positional relations between the Gaussian plume and the human bodysignificantly affect the features of the radiation fields at the location where doses areevaluated (Saito et al., 1998). For example, photons enter a human body mostly from above, if
the human body is positioned below the plume; while, incident angles of photons are biased inhorizontal directions, if the human body is at a far distance from the plume. Evaluating dose
40

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138

1139
1140
1141
1142
1143
1144
1145
1146
1147
1148

rate coefficients considering these complex situations is not practical, and thus the submersion
model of this report is a reasonable approximation of exposures for most cases. Fig. 5.5 shows
schematically the air submersion geometry. The geometry is considered to be semi-infinite inextent. The ground interface is assumed to be an uncontaminated flat surface of infinite area.
The elemental composition of air is shown in Table 5.1 and corresponds to dry air at a densityof 1.2 x 10-3 g cm-3. Bellamy et al. (2018) have estimated air kerma as a function of air
density and shows an example of these results for 1 MeV photons. The authors found that thefunctional relation between air kerma and air density is virtually independent of photon
energy. Using these values, the dose rate coefficients for air submersion can be scaled toaccount for different air densities. With increasing humidity, the air density increases andconsequently the air kerma decreases (see Fig. 5.6). Thus, the dose rate coefficient per air
kerma increases with increasing humidity.
(72) The number of histories, reduction variance techniques, and scoring of the particles
were similar to those mentioned above for soil contamination.
(73) The particles originated from the air region are transported and scored on the surfaceof the coupling cylinder, placed on the air ground interface. The coupling surface records the
position, angle, energy of incident photons, and Monte Carlo weight as discussed in Section
5.1 regarding soil contamination. This method produces energy-dependent fluences. As forthe soil contamination exposure scenario, calculations were performed for 25 monoenergetic
sources of photons and electrons ranging from 0.01 to 8 MeV.

Fig. 5.5. Schematic view of the geometry simulating submersion into contaminated air. The
region coloured with yellow indicates the source region. For organ equivalent dose
calculations, the medium inside the coupling cylinder is air. For electron exposures, theparticles start not only from the surface of the cylinder but also from the inside of the cylinder(for photons this is not necessary since the mean free path of photons in air is long and thesource inside the cylinder does not significantly contribute to the results of organ equivalentdose calculations).

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DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1149
1150
1151
1152
1153
1154
1155
1156
1157

Fig. 5.6 Air kerma as a function of air density for 1 MeV photons from Bellamy et al. (2018).
(74) Fig. 5.7 shows the energy spectrum of environmental photons from a source of 0.5
MeV at heights 0 - 0.40 m and 1.60 - 2.00 m. The incident directions of photons are expressedas the sine of the vector parallel to the ground surface. It can be seen that for many photons,
no scattering is observed and most photons come from upper directions with little dependenceof their directional distribution on height.

1158
1159
1160
1161
1162
1163
1164
1165

Fig. 5.7. Energy (left) and angular (right) distribution of a semi-infinite source in the air
emitting 0.5 MeV monoenergetic photons. (left) The y axis shows the number of photons perenergy bin. (right) The y axis shows the number of photons per sine angle at the indicatedheight range. To differentiate these distributions from the respective spectrum for all heights(Φ), they are marked by the superscript j.

1166

5.3. Water immersion

1167
1168

(75) Water immersion might be rare in the pathway of environmental exposure.
Nevertheless, many facilities have routine liquid effluent releases, and radioactive releases to42

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188

the sea or contamination of surface waters have been observed after major radiologicalaccidents. Highly contaminated water from a damaged reactor core and water pools resulting
from damaged nuclear fuels can be released through direct or ground water discharge, as theyoccurred as a consequence of the accident at the nuclear power plant in Fukushima Prefecture,
Japan, in 2011 (Buesseler et al., 2017). Radionuclides such as radioactive iodine and caesium
were detected in tap water and the exposure due to contaminated water used for bathing had
to be estimated. Moreover, radionuclides were also released into the sea and could be
potentially harmful for people who enter the sea around the power plant following theaccident.
(76) Fig. 5.8 shows schematically the water immersion geometry. The source geometry is
assumed to be infinite in extent. The water density is 1.0 × 103 kg m-3 and the composition bymass fraction is 0.112 for H and 0.888 for O, representing pure liquid water. The phantoms
are assumed to be completely immersed in the water and are placed at the centre of a spherewith a radius of 2 m, corresponding to 5 mfp at a photon energy of 8 MeV in water.
Monoenergetic sources photons and electrons are generated uniformly in the contaminatedwater. As for the other geometries, bremsstrahlung photons are directly transported by the
PHITS Monte Carlo transport code. The organ equivalent dose rate coefficients for water
immersion of the male and female phantoms at the six reference ages have been calculated ina single-step and thus no coupling cylinder was required.

1189
1190
1191
1192

Fig. 5.8. Schematic view of water immersion. The sphere is centred on the midpoint of thethree axes of the phantom.

1193
1194

5.4. Calculation of air kerma and ambient dose equivalent in theenvironmental field

1195
1196
1197
1198
1199
1200
1201
1202
1203

(77) Air kerma and ambient dose equivalent has been widely used for the purpose ofradiation protection after environmental exposures (ICRU, 1994; IAEA, 2000b). The air
kerma is a basic quantity related to photon energy fluence, and in natural environments it issubstantially equivalent to the air absorbed dose which has been used by UNSCEAR toexpress dose rates in air (UNSCEAR, 2000, 2008). Absorbed dose in air has been used inenvironmental monitoring for many years, but it has been gradually replaced by theoperational quantity ambient dose equivalent as seen in worldwide environmental monitoringdata (European Commission Joint Research Centre, 2017). The ambient dose equivalent,
defined as the dose equivalent for aligned and expanded radiation fields at a depth of 10 mm
43

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1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240

in the International Commission on Radiation Units and Measurements (ICRU) sphereconsisting of ICRU 4-element tissue, is aimed to conservatively evaluate effective doses fordiverse exposures (ICRU, 1993). Though originally the operational quantity ambient dose
equivalent was introduced for radiation protection of workers (workplace monitoring), thisdosimetric quantity has also been applied to environmental monitoring: the instruments formonitoring of H*(10) generally have an isotropic response with respect to both energy andangular distributions of incident photons. Resultantly, these instruments work well inenvironmental fields which exhibit complex angular and energy distributions, even if they are
calibrated under simple conditions such as for unidirectional irradiation using monoenergetic
sources. Consequently, environmental monitoring data worldwide are generally expressed asdose rates in air reported as the operational quantity ambient dose equivalent (European
Commission Joint Research Centre, 2017).
(78) In order to relate the air contamination and ground deposition densities of aradionuclide to dose rates in air, coefficients are required for both air kerma and ambient dose
equivalent rates. Many authors have published coefficients relating radionuclide concentrationin the environment to air kerma rate (Dillman, 1974; O' Brien and Sanna, 1976; ICRU, 1994;
Saito and Jacob, 1995), and to ambient equivalent rate (Lemercier et al., 2008; Saito andPetoussi-Henss, 2014), and these data have been used in environmental dose evaluations. In
the present report, these coefficients have been recalculated considering air kerma andambient dose equivalent rates at 1 m height above ground for both the soil contamination andair submersion exposure geometries described above from monoenergetic photon sources. For
the simulations, the Monte Carlo code PHITS (see section 5) was used and the sameenvironmental conditions were considered as those applied in the calculation of theenvironmental fields – see sections 5.1 and 5.2.
(79) The calculation was made by simulating a 30 cm diameter sphere filled with andsurrounded by air, at 1 m above the ground and by scoring the particles entering the sphere.
The 30 cm sphere represents the size of a human torso and this size was consideredappropriate. The transport simulation was restarted from the surface of the coupling cylinderusing the data in the external file created in the Step 1 of the calculations. Fig. 5.9 shows aschematic representation of the calculation geometry. The photon fluence scored at the air
sphere is then converted to an air kerma rate and ambient dose equivalent rate using the dosecoefficients given in Publication 74 (ICRP, 1996b). The relative uncertainties of thesequantities were less than 1%.
(80) For soil and air contamination, the air kerma depends on the distance from the ground;while this dependence is weak for sources in air, it is pronounced for planar sources in the
ground.

44

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Diameter: 0.30 m

1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273

Fig. 5.9. Schematic representation of calculation of air kerma and ambient dose equivalent.
(81) On the basis of these results, ambient dose equivalent rate coefficients, ℎ̇∗ (10)), in
units of nSv h-1 Bq-1 m2 or nSv h-1 Bq-1 m3 can be derived to relate the activity concentration
to the ambient dose equivalent rate. Thus, the ambient dose equivalent rate can be
subsequently related to the effective dose rate.
(82) Individual monitoring of the effective dose is performed with dosimeters calibrated interms of personal dose equivalent, Hp(d). The Task Group which developed this publication
decided not to include dose coefficients for Hp(d). Hp(d) is defined as the dose equivalent insoft tissue, at an appropriate depth, d, below a specified point on the body. The specified point
is usually given by the position where the individual’s dosimeter is worn. Calibration of
personal dosimeters is performed by exposure to unidirectional radiation at an incident angle(α), where α is the angle between the direction of incidence of radiation and the reference
direction of the personal dosimeter mounted on the front face of the calibration phantom.
These calibrations are typically performed for normally incidence radiations i.e. α=0.0. On
the other hand, for the environmental fields considered in this publication, photons of wide
energy distribution are incident from various angles. Standardising reference radiation fields
and calibration procedures simulating the environmental radiation have not been
recommended by international organisations, such as the International Organization forStandardization (ISO) and the International Electrotechnical Commission (IEC). The
coefficients for Hp(10) could be calculated using phantoms and environmental radiation
sources by Monte Carlo simulations. However, methods of calibration of personal dosimeters
to link dosimeter readings to the dose rate coefficients of Hp(d) have not yet been establishedfor environmental exposures.
(83) Individual monitoring in environmental radiation fields has often been performed inJapan after 2011, with dosimeters calibrated by irradiation of unidirectional radiation (Nuclear
Regulation Authority Japan website, 2013). It is of significant concern whether the personal
dosimeters calibrated in this way provide reasonable values for assessment of effective dosein the environmental fields. To address the question, Satoh et al. (2017) analysed the relationof E, H*(10), and Hp(10) in radiation fields originating from photon emissions from both134
Cs and 137Cs distributed in different depths in soil, where the personal dosimeters were
calibrated under the above simplified exposure conditions. A conclusion of their analysis is45

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1274
1275
1276

that, both area monitoring and individual monitoring do provide reasonable estimates ofeffective dose, for the conditions investigated.

46

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1277
1278

6. DETERMINATION OF DOSE RATE COEFFICIENTS FORMONOENERGETIC PARTICLES (STEP 2)

1279
1280

6.1. Monte Carlo photon and electron transport calculation in theanthropomorphic phantoms

1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320

(84) For the above discussed exposure geometries of contaminated soil and air, Step 2
calculations involved the computation of organ equivalent dose rate coefficients in eachgender-age-specific phantom resulting from the simulated radiation fields from Step 1
calculations. The recorded particle histories on the coupling cylinder were used as the source
irradiating the phantom and each phantom was placed inside the air-filled coupling cylinder.
(85) Particle transport calculations starting from the surface of the coupling cylinder were
performed with PHITS, version 2.66 (Sato et al., 2013). The atomic data libraries MCPLIB04(White, 2003) and EL03 (Adams, 2000) were utilised for photon and electron transport,
respectively.
(86) Step 2 considers photon as well as electron fields as these were recorded on the
coupling cylinder. For photon fields, also secondary electrons were transported. The
combined relative uncertainty (i.e. one standard deviation) from both Steps 1 and 2
computations was less than 10% for most organs and tissues, where the dominating
contribution stems from the environmental field calculations.
(87) The computational methods for determining the equivalent dose rate to active marrowand skeletal endosteum are described in Annex A.
(88) For evaluating the absorbed doses to the sensitive layer of the skin, which isconsidered to be 50-100 µm below the skin surface, polygon mesh formats of the reference
phantoms were applied, together with the Monte Carlo code GEANT4 (Agostinelli et al.,2003). Further details on estimates of skin dose are given in Annex B.
(89) The organ equivalent doses were evaluated in the form of dose rate coefficients giving
the mean organ equivalent dose rate normalised to a measurable environmental radioactivity
quantity. The doses are then estimated on the basis of the measured ground deposition levels(i.e. surface activity densities) or photon dose rate in the air, normalised to a unit deposit ofeach radionuclide. As gamma ray measurements in the environment are performed at a heightof 1 m above the ground surface, the normalisation quantity for measurements in air was
selected to be air kerma and ambient dose equivalent at height 1 m above the ground at theposition of the body's longitudinal axis. Values of air kerma at 1 m height above the groundnormalized to source activity are also given (see section 6.2). These coefficients are used tofacilitate normalisation to source activity (i.e. photon emission per unit area or per unit
volume).
(90) Organ equivalent dose rate coefficients for all defined organs/tissues, including all
those explicitly noted in the definition of the effective dose, are given as equivalent dose rates
per radioactivity concentration. Since this document refers to environmental exposures ofphotons and electrons, both of which have radiation weighting factor (wR) equals to unity, theequivalent dose coefficients are numerically equivalent to their corresponding absorbed dosecoefficients.
(91) In order to avoid fluctuation by statistical uncertainty and obtain smooth curves of theorgan equivalent dose rate coefficients as a function of photon and electron energy, data
fitting was applied using the piecewise cubic Hermite function (Fritsch and Carlson, 1980).

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1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333

(92) It should be noted that, for monoenergetic photon and electron sources below 0.05 and0.10 MeV, respectively, the organ equivalent dose rate coefficients were set to zero, if theircontribution to effective dose was below 1% and the value of the precedent energy was zero.
This was done to avoid discontinuities on the curves or to improve their smoothness.
(93) Reference values of the equivalent dose rate coefficients of organs and tissues forwhich tissue weighting factors are defined (ICRP, 2007), as well as for the remainder tissues,
can be found in the electronic supplement to this report. The data are given separately for the
male and female adult and paediatric reference phantoms. These, since they have been
calculated with the ICRP reference phantoms, for reference geometries and following ICRP
methodology, are considered to be the ICRP reference data.
(94) The results of these calculations are used to derive radionuclide-specific dose rate
coefficients through energy interpolation to obtain coefficients for the detailed photon andelectron decay spectrum of each radionuclide as given in Publication 107 - see section 7.

1334

6.2. Dose rate coefficients for soil contamination

1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350

(95) The absorbed dose delivered to internal organs and tissues is calculated by exposing
the computational phantoms to the radiation fields obtained previously. The particle transport
is re-started based on information on the particles histories written in the external file during
the Step 1. The calculation efficiency is significantly improved by using the environmental
radiation field obtained in the Step 1 which is in common to the Step 2 calculations for eachreference phantom age and gender.
(96) The right side of the Fig. 6.1 illustrates the geometry of the Step 2 calculation. The
phantom is placed inside the coupling cylinder, and the remaining space is filled with air.
Owing to the fact that the simulation geometry is cylindrically symmetric, the transport
calculation is repeated 36 times by rotating the source position in 10° steps at the surface ofthe cylinder around the central axis to avoid any directional bias.

48

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1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383

Fig. 6.1. Schematic representation of the geometry simulating the soil contamination. Leftdescribes the Step 1 of the calculation and the right side of the Figure, the Step 2. “mfp”
indicates mean free path.
(97) Dose rate coefficients for soil contamination were evaluated as the effective dose rate
per activity concentration for monoenergetic sources of photons and electrons in soil, whoseenergy ranges from 0.01 to 8 MeV along 25 energy points. The coefficients are given in theunit of nSv h-1 Bq-1 m2. The effective dose rates were computed from the data of organ
equivalent dose rates computed using the ICRP adult and paediatric (newborn, 1-, 5-, 10- and15-year-old) reference computational phantoms as described in Section 4.2. The data forphotons were evaluated for the sources uniformly distributed in the soil over a planar area andat specific depths of 0.0, 0.2, 1.0, 2.5 and 4.0 mfp for the photons emitted in the soil.
Electrons were evaluated only for the sources located on the air-ground interface (i.e. noaccounting for electrons emitted at depth within the soil).
(98) For each source depth, 10 – 20 million photon histories were started, depending on thephoton energy, from the recorded distributions on the coupling cylinder. This led tocoefficients of variance that were generally around 0.5% for large organs and around 1% forsmall organs. For electron irradiations, 20 million – 2 billion particle histories were followed.
This led to coefficients of variance that were generally around 5% for all organs. Note thatthese coefficients of variance refer only to Step 2 organ equivalent dose calculations and not
to the environmental field calculations.
(99) For photon sources, coefficients for air kerma and ambient dose equivalent rates werealso evaluated in air at a height of 1m above the ground as described in Section 5.4.
(100) The effective dose rate coefficients are given in Tables 6.1 to 6.5 for photon sources
at specific depths of 0.0, 0.2, 1.0, 2.5 and 4.0 mfp for photons emitted within the soil together
with the data on the corresponding air kerma rates and ambient dose equivalent rates. The
effective dose rate coefficient for electron sources on the ground surface are given in Table
6.6. Effective dose rate coefficients are shown graphically in Fig. 6.2 to Fig. 6.7. The
equivalent dose rate coefficients for all organs contributing to the effective dose as well as of
the remainder tissues are tabulated in regard to both age and gender, and are compiled in anelectronic supplement to this publication.
49

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398

(101) These figures demonstrate the age-dependence of the effective dose rate forenvironmental photon and electron exposures. For most energies and all geometries, thesmaller the phantom, the larger the effective dose rate coefficient. Larger differences areobserved for the adult phantom and the newborn which could amount to 140% for energies
lower than 50 keV and contamination on the surface of the ground. Also, it can be seen thatthe ambient dose equivalent rate, ℎ̇∗ (10), for most cases, is a conservative approximation of
the effective dose. Exceptions are observed for the newborn phantoms, the 1-year-old and 5year-old phantoms at energy of 0.01 MeV, where the effective dose rate coefficient is higher
than the ambient dose equivalent rate, ℎ̇∗ (10). This could be explained by considering that,for decreasing photon energies, the mean free path of photons in air is also decreasing. ℎ̇∗ (10)is estimated in air at 1 m height from the ground surface, whereas the phantoms are standingon the ground surface. Furthermore, it can be noted that, ℎ̇∗ (10), becomes more and moreconservative as the source depth increases. This could be explained by the photon energy
spectrum which is shifted to lower energies.

50

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1399
1400
1401
1402

Table 6.1. Effective dose rate, ambient dose equivalent rate and air kerma rate coefficients formonoenergetic photon sources distributed at a depth of 0.0 mean free paths in the soil.
Ambient dose equivalent rate and air kerma rate coefficients were calculated at 1 m above
ground.
EnergyEffective dose rate coefficient(MeV)(nSv h-1 Bq-1 m2)
Adult

15 yr

10 yr

5 yr

ℎ∗̇ (10)
1 yr(nGy h-1
Bq-1 m2)

Newborn

0.010

5.33E-06 5.15E-06 7.04E-06 8.97E-06 1.70E-05 3.25E-05 5.24E-06 6.36E-04

0.015

1.41E-05 1.58E-05 2.50E-05 3.12E-05 4.65E-05 9.23E-05 2.06E-04 7.86E-04

0.020

2.89E-05 3.42E-05 4.57E-05 6.55E-05 8.39E-05 1.51E-04 4.14E-04 6.73E-04

0.030

7.23E-05 8.32E-05 1.01E-04 1.43E-04 1.80E-04 2.68E-04 4.92E-04 4.49E-04

0.040

1.12E-04 1.27E-04 1.48E-04 1.94E-04 2.39E-04 3.15E-04 4.89E-04 3.40E-04

0.050

1.43E-04 1.61E-04 1.88E-04 2.29E-04 2.80E-04 3.41E-04 4.85E-04 2.96E-04

0.060

1.77E-04 1.94E-04 2.18E-04 2.56E-04 3.07E-04 3.63E-04 5.02E-04 2.94E-04

0.070

2.08E-04 2.27E-04 2.51E-04 2.90E-04 3.41E-04 3.93E-04 5.29E-04 3.06E-04

0.080

2.39E-04 2.59E-04 2.85E-04 3.26E-04 3.80E-04 4.29E-04 5.64E-04 3.30E-04

0.100

3.02E-04 3.24E-04 3.48E-04 3.90E-04 4.52E-04 5.13E-04 6.64E-04 3.98E-04

0.150

4.65E-04 4.92E-04 5.30E-04 5.97E-04 6.81E-04 7.70E-04 9.57E-04 6.25E-04

0.200

6.28E-04 6.66E-04 7.15E-04 8.09E-04 9.16E-04 1.04E-03 1.25E-03 8.60E-04

0.300

9.67E-04 1.02E-03 1.10E-03 1.23E-03 1.39E-03 1.59E-03 1.82E-03 1.34E-03

0.400

1.31E-03 1.37E-03 1.49E-03 1.65E-03 1.87E-03 2.13E-03 2.38E-03 1.82E-03

0.500

1.66E-03 1.72E-03 1.87E-03 2.07E-03 2.34E-03 2.67E-03 2.91E-03 2.29E-03

0.600

2.01E-03 2.07E-03 2.24E-03 2.47E-03 2.78E-03 3.18E-03 3.41E-03 2.74E-03

0.800

2.63E-03 2.72E-03 2.92E-03 3.20E-03 3.58E-03 4.08E-03 4.28E-03 3.52E-03

1.000

3.12E-03 3.25E-03 3.49E-03 3.78E-03 4.20E-03 4.75E-03 4.86E-03 4.10E-03

1.500

4.57E-03 4.68E-03 5.02E-03 5.42E-03 5.93E-03 6.65E-03 6.69E-03 5.77E-03

2.000

5.87E-03 6.01E-03 6.43E-03 6.92E-03 7.50E-03 8.38E-03 8.36E-03 7.31E-03

3.000

8.18E-03 8.43E-03 8.97E-03 9.61E-03 1.03E-02 1.14E-02 1.13E-02 1.01E-02

4.000

1.02E-02 1.06E-02 1.12E-02 1.20E-02 1.27E-02 1.40E-02 1.39E-02 1.25E-02

5.000

1.21E-02 1.25E-02 1.32E-02 1.41E-02 1.48E-02 1.62E-02 1.63E-02 1.47E-02

6.000

1.38E-02 1.44E-02 1.51E-02 1.61E-02 1.68E-02 1.83E-02 1.84E-02 1.67E-02

8.000

1.76E-02 1.80E-02 1.91E-02 2.03E-02 2.09E-02 2.26E-02 2.28E-02 2.10E-02

1403
1404

51

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1405
1406
1407
1408

Table 6.2. Effective dose rate, ambient dose equivalent rate and air kerma rate coefficients formonoenergetic photon sources distributed at a depth of 0.2 mean free paths in the soil.
Ambient dose equivalent rate and air kerma rate coefficients were calculated at 1 m above
ground.
EnergyEffective dose rate coefficient(MeV)(nSv h-1 Bq-1 m2)
Adult

15 yr

10 yr

5 yr

ℎ∗̇ (10)
1 yr(nGy h-1
Bq-1 m2)

Newborn

0.010

3.02E-06 2.89E-06 4.18E-06 4.90E-06 9.31E-06 1.65E-05 3.58E-06 4.36E-04

0.015

7.40E-06 8.21E-06 1.34E-05 1.55E-05 2.23E-05 3.80E-05 1.19E-04 4.54E-04

0.020

1.44E-05 1.61E-05 2.21E-05 3.05E-05 3.16E-05 5.30E-05 2.05E-04 3.33E-04

0.030

3.06E-05 3.53E-05 4.22E-05 5.47E-05 6.06E-05 8.69E-05 2.22E-04 2.04E-04

0.040

4.73E-05 5.34E-05 6.18E-05 7.64E-05 8.44E-05 1.03E-04 2.23E-04 1.57E-04

0.050

6.42E-05 7.15E-05 8.02E-05 9.60E-05 1.07E-04 1.24E-04 2.29E-04 1.42E-04

0.060

8.17E-05 8.92E-05 9.90E-05 1.15E-04 1.26E-04 1.38E-04 2.46E-04 1.46E-04

0.070

9.98E-05 1.08E-04 1.18E-04 1.32E-04 1.45E-04 1.56E-04 2.71E-04 1.59E-04

0.080

1.17E-04 1.26E-04 1.36E-04 1.50E-04 1.64E-04 1.75E-04 3.00E-04 1.76E-04

0.100

1.50E-04 1.59E-04 1.69E-04 1.87E-04 1.98E-04 2.11E-04 3.55E-04 2.12E-04

0.150

2.33E-04 2.43E-04 2.60E-04 2.84E-04 3.03E-04 3.21E-04 5.13E-04 3.29E-04

0.200

3.03E-04 3.21E-04 3.44E-04 3.76E-04 3.98E-04 4.28E-04 6.56E-04 4.41E-04

0.300

4.38E-04 4.63E-04 4.95E-04 5.41E-04 5.70E-04 6.17E-04 9.04E-04 6.43E-04

0.400

5.66E-04 5.89E-04 6.29E-04 6.86E-04 7.20E-04 7.80E-04 1.11E-03 8.22E-04

0.500

6.88E-04 7.06E-04 7.50E-04 8.17E-04 8.55E-04 9.27E-04 1.29E-03 9.83E-04

0.600

8.01E-04 8.16E-04 8.65E-04 9.39E-04 9.82E-04 1.06E-03 1.45E-03 1.13E-03

0.800

9.97E-04 1.04E-03 1.10E-03 1.18E-03 1.24E-03 1.34E-03 1.77E-03 1.42E-03

1.000

1.15E-03 1.19E-03 1.25E-03 1.33E-03 1.40E-03 1.51E-03 1.94E-03 1.59E-03

1.500

1.58E-03 1.62E-03 1.70E-03 1.80E-03 1.89E-03 2.04E-03 2.51E-03 2.12E-03

2.000

1.95E-03 2.00E-03 2.09E-03 2.21E-03 2.31E-03 2.48E-03 3.00E-03 2.57E-03

3.000

2.56E-03 2.62E-03 2.73E-03 2.87E-03 2.99E-03 3.19E-03 3.79E-03 3.31E-03

4.000

3.05E-03 3.11E-03 3.22E-03 3.38E-03 3.50E-03 3.71E-03 4.38E-03 3.85E-03

5.000

3.45E-03 3.52E-03 3.62E-03 3.79E-03 3.89E-03 4.12E-03 4.84E-03 4.29E-03

6.000

3.82E-03 3.90E-03 3.98E-03 4.17E-03 4.25E-03 4.47E-03 5.24E-03 4.68E-03

8.000

4.67E-03 4.77E-03 4.83E-03 5.07E-03 5.09E-03 5.33E-03 6.18E-03 5.62E-03

1409
1410

52

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1411
1412
1413
1414

Table 6.3. Effective dose rate, ambient dose equivalent rate and air kerma rate coefficients formonoenergetic photon sources distributed at a depth of 1.0 mean free paths in the soil.
Ambient dose equivalent rate and air kerma rate coefficients were calculated at 1 m above
ground.
EnergyEffective dose rate coefficient(MeV)(nSv h-1 Bq-1 m2)
Adult

15 yr

10 yr

5 yr

ℎ∗̇ (10)
1 yr(nGy h-1
Bq-1 m2)

Newborn

0.010

7.79E-07 7.40E-07 1.07E-06 1.18E-06 2.09E-06 3.28E-06 1.05E-06 1.28E-04

0.015

1.62E-06 1.75E-06 2.83E-06 3.03E-06 4.25E-06 6.41E-06 2.78E-05 1.07E-04

0.020

2.85E-06 3.25E-06 4.37E-06 5.41E-06 6.44E-06 9.45E-06 4.54E-05 7.41E-05

0.030

6.09E-06 6.84E-06 8.20E-06 1.05E-05 1.23E-05 1.67E-05 5.03E-05 4.64E-05

0.040

1.06E-05 1.17E-05 1.33E-05 1.66E-05 1.88E-05 2.34E-05 5.56E-05 3.97E-05

0.050

1.60E-05 1.76E-05 1.94E-05 2.29E-05 2.61E-05 3.04E-05 6.33E-05 3.99E-05

0.060

2.21E-05 2.42E-05 2.68E-05 3.08E-05 3.33E-05 3.83E-05 7.53E-05 4.51E-05

0.070

2.87E-05 3.15E-05 3.46E-05 3.91E-05 4.20E-05 4.66E-05 8.92E-05 5.25E-05

0.080

3.58E-05 3.90E-05 4.26E-05 4.76E-05 5.13E-05 5.53E-05 1.04E-04 6.13E-05

0.100

5.02E-05 5.36E-05 5.78E-05 6.41E-05 6.91E-05 7.27E-05 1.34E-04 7.96E-05

0.150

8.22E-05 8.73E-05 9.25E-05 1.02E-04 1.09E-04 1.15E-04 2.01E-04 1.26E-04

0.200

1.10E-04 1.17E-04 1.24E-04 1.36E-04 1.44E-04 1.52E-04 2.60E-04 1.70E-04

0.300

1.58E-04 1.66E-04 1.77E-04 1.93E-04 2.02E-04 2.15E-04 3.56E-04 2.44E-04

0.400

1.96E-04 2.05E-04 2.19E-04 2.38E-04 2.48E-04 2.66E-04 4.27E-04 3.04E-04

0.500

2.26E-04 2.36E-04 2.52E-04 2.73E-04 2.84E-04 3.06E-04 4.79E-04 3.52E-04

0.600

2.51E-04 2.61E-04 2.78E-04 3.01E-04 3.13E-04 3.39E-04 5.16E-04 3.89E-04

0.800

2.90E-04 3.02E-04 3.19E-04 3.45E-04 3.61E-04 3.90E-04 5.71E-04 4.42E-04

1.000

3.28E-04 3.41E-04 3.60E-04 3.88E-04 4.07E-04 4.37E-04 6.22E-04 4.91E-04

1.500

4.22E-04 4.37E-04 4.59E-04 4.93E-04 5.16E-04 5.52E-04 7.48E-04 6.11E-04

2.000

5.01E-04 5.19E-04 5.43E-04 5.81E-04 6.08E-04 6.50E-04 8.52E-04 7.11E-04

3.000

6.24E-04 6.49E-04 6.75E-04 7.18E-04 7.48E-04 7.97E-04 1.01E-03 8.62E-04

4.000

7.09E-04 7.45E-04 7.70E-04 8.13E-04 8.44E-04 8.96E-04 1.11E-03 9.63E-04

5.000

7.72E-04 8.17E-04 8.42E-04 8.83E-04 9.13E-04 9.64E-04 1.18E-03 1.03E-03

6.000

8.24E-04 8.79E-04 9.03E-04 9.42E-04 9.69E-04 1.02E-03 1.23E-03 1.09E-03

8.000

9.48E-04 1.02E-03 1.05E-03 1.09E-03 1.11E-03 1.16E-03 1.37E-03 1.23E-03

1415
1416

53

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1417
1418
1419
1420

Table 6.4. Effective dose rate, Ambient dose equivalent rate and air kerma rate coefficientsfor monoenergetic photon sources distributed at a depth of 2.5 mean free paths in the soil.
Ambient dose equivalent rate and air kerma rate coefficients were calculated at 1 m above
ground.
EnergyEffective dose rate coefficient(MeV)(nSv h-1 Bq-1 m2)
Adult

15 yr

10 yr

5 yr

ℎ∗̇ (10)1 yr

nGy h-1
Bq-1 m2)

Newborn

0.010

9.54E-08 9.07E-08 1.38E-07 1.35E-07 2.29E-07 3.81E-07 1.43E-07 1.74E-05

0.015

1.86E-07 2.02E-07 3.38E-07 3.16E-07 4.54E-07 6.91E-07 3.45E-06 1.23E-05

0.020

3.24E-07 3.83E-07 5.11E-07 5.63E-07 6.95E-07 1.00E-06 5.78E-06 9.44E-06

0.030

7.53E-07 8.47E-07 9.67E-07 1.28E-06 1.52E-06 2.05E-06 7.00E-06 6.50E-06

0.040

1.47E-06 1.60E-06 1.79E-06 2.19E-06 2.51E-06 3.21E-06 8.47E-06 6.07E-06

0.050

2.42E-06 2.71E-06 3.00E-06 3.58E-06 4.02E-06 4.88E-06 1.08E-05 6.83E-06

0.060

3.80E-06 4.15E-06 4.55E-06 5.34E-06 5.82E-06 6.72E-06 1.41E-05 8.47E-06

0.070

5.35E-06 5.79E-06 6.30E-06 7.26E-06 7.77E-06 8.75E-06 1.76E-05 1.04E-05

0.080

7.04E-06 7.58E-06 8.21E-06 9.36E-06 9.91E-06 1.10E-05 2.13E-05 1.26E-05

0.100

1.07E-05 1.14E-05 1.23E-05 1.38E-05 1.45E-05 1.58E-05 3.01E-05 1.79E-05

0.150

1.90E-05 2.03E-05 2.17E-05 2.40E-05 2.54E-05 2.67E-05 4.96E-05 3.09E-05

0.200

2.56E-05 2.73E-05 2.90E-05 3.21E-05 3.39E-05 3.57E-05 6.50E-05 4.18E-05

0.300

3.59E-05 3.81E-05 4.05E-05 4.48E-05 4.76E-05 5.03E-05 8.87E-05 5.95E-05

0.400

4.38E-05 4.63E-05 4.92E-05 5.43E-05 5.77E-05 6.13E-05 1.05E-04 7.27E-05

0.500

4.98E-05 5.24E-05 5.56E-05 6.14E-05 6.50E-05 6.93E-05 1.15E-04 8.22E-05

0.600

5.43E-05 5.70E-05 6.05E-05 6.65E-05 7.01E-05 7.51E-05 1.21E-04 8.92E-05

0.800

6.08E-05 6.35E-05 6.73E-05 7.37E-05 7.71E-05 8.31E-05 1.32E-04 9.94E-05

1.000

6.70E-05 7.01E-05 7.42E-05 8.10E-05 8.45E-05 9.13E-05 1.41E-04 1.09E-04

1.500

7.82E-05 8.16E-05 8.64E-05 9.41E-05 9.79E-05 1.06E-04 1.57E-04 1.26E-04

2.000

8.78E-05 9.11E-05 9.64E-05 1.05E-04 1.09E-04 1.18E-04 1.70E-04 1.40E-04

3.000

1.03E-04 1.07E-04 1.13E-04 1.22E-04 1.26E-04 1.37E-04 1.89E-04 1.61E-04

4.000

1.15E-04 1.18E-04 1.25E-04 1.34E-04 1.39E-04 1.49E-04 2.01E-04 1.74E-04

5.000

1.23E-04 1.27E-04 1.34E-04 1.44E-04 1.48E-04 1.58E-04 2.08E-04 1.82E-04

6.000

1.30E-04 1.35E-04 1.41E-04 1.51E-04 1.54E-04 1.64E-04 2.12E-04 1.87E-04

8.000

1.42E-04 1.49E-04 1.56E-04 1.64E-04 1.68E-04 1.76E-04 2.22E-04 1.97E-04

1421
1422
1423
54

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1424
1425
1426

Table 6.5. Effective dose rate, ambient dose equivalent rate and air kerma rate coefficients formonoenergetic photon sources distributed at a depth of 4 mean free paths in the soil. Ambient
dose equivalent rate and air kerma rate coefficients were calculated at 1 m above ground.

EnergyEffective dose rate coefficient(MeV)(nSv h-1 Bq-1 m2)
Adult

15 yr

10 yr

ℎ∗̇ (10)
5 yr

1 yr

nGy h-1
Bq-1 m2)

Newborn

0.010

1.48E-08 1.39E-08 2.09E-08 2.08E-08 3.29E-08 5.34E-08 2.32E-08 2.82E-06

0.015

2.79E-08 3.01E-08 4.83E-08 4.82E-08 6.61E-08 9.63E-08 5.59E-07 2.03E-06

0.020

5.02E-08 5.79E-08 7.65E-08 8.73E-08 1.03E-07 1.52E-07 9.55E-07 1.56E-06

0.030

1.20E-07 1.40E-07 1.57E-07 2.05E-07 2.40E-07 3.26E-07 1.23E-06 1.14E-06

0.040

2.44E-07 2.79E-07 3.06E-07 3.69E-07 4.42E-07 5.59E-07 1.54E-06 1.10E-06

0.050

4.42E-07 4.97E-07 5.49E-07 6.57E-07 7.48E-07 8.74E-07 2.11E-06 1.35E-06

0.060

7.69E-07 8.46E-07 9.18E-07 1.09E-06 1.19E-06 1.32E-06 3.04E-06 1.82E-06

0.070

1.15E-06 1.24E-06 1.34E-06 1.56E-06 1.67E-06 1.83E-06 3.95E-06 2.33E-06

0.080

1.55E-06 1.67E-06 1.80E-06 2.08E-06 2.20E-06 2.37E-06 4.89E-06 2.89E-06

0.100

2.45E-06 2.63E-06 2.84E-06 3.20E-06 3.40E-06 3.59E-06 7.15E-06 4.24E-06

0.150

4.81E-06 5.09E-06 5.54E-06 6.08E-06 6.47E-06 6.76E-06 1.30E-05 8.10E-06

0.200

6.65E-06 7.04E-06 7.66E-06 8.36E-06 8.90E-06 9.35E-06 1.76E-05 1.13E-05

0.300

9.13E-06 9.93E-06 1.08E-05 1.17E-05 1.24E-05 1.31E-05 2.41E-05 1.60E-05

0.400

1.09E-05 1.18E-05 1.27E-05 1.38E-05 1.46E-05 1.55E-05 2.77E-05 1.90E-05

0.500

1.22E-05 1.28E-05 1.37E-05 1.50E-05 1.58E-05 1.68E-05 2.95E-05 2.08E-05

0.600

1.30E-05 1.35E-05 1.43E-05 1.57E-05 1.65E-05 1.76E-05 3.02E-05 2.18E-05

0.800

1.39E-05 1.48E-05 1.56E-05 1.71E-05 1.79E-05 1.92E-05 3.20E-05 2.39E-05

1.000

1.47E-05 1.53E-05 1.61E-05 1.76E-05 1.84E-05 1.97E-05 3.29E-05 2.46E-05

1.500

1.65E-05 1.74E-05 1.83E-05 1.99E-05 2.08E-05 2.22E-05 3.45E-05 2.72E-05

2.000

1.81E-05 1.90E-05 2.01E-05 2.19E-05 2.27E-05 2.43E-05 3.59E-05 2.93E-05

3.000

2.04E-05 2.15E-05 2.28E-05 2.47E-05 2.55E-05 2.72E-05 3.83E-05 3.26E-05

4.000

2.20E-05 2.31E-05 2.45E-05 2.64E-05 2.72E-05 2.88E-05 4.00E-05 3.48E-05

5.000

2.32E-05 2.41E-05 2.56E-05 2.75E-05 2.82E-05 2.97E-05 4.13E-05 3.64E-05

6.000

2.41E-05 2.50E-05 2.66E-05 2.84E-05 2.89E-05 3.03E-05 4.25E-05 3.78E-05

8.000

2.66E-05 2.78E-05 2.98E-05 3.13E-05 3.18E-05 3.26E-05 4.49E-05 4.16E-05

1427
1428

55

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1429
1430
1431

Table 6.6. Effective dose rate coefficients for monoenergetic electron sources distributed at a
depth of 0.0 mean free paths in the soil.
EnergyEffective dose rate coefficient(MeV)(nSv h-1 Bq-1 m2)
Adult

15 yr

10 yr

5 yr

1 yr

Newborn

0.010

2.44E-10

2.25E-10

2.21E-10

2.26E-10

2.22E-10

5.49E-10

0.015

6.18E-10

6.83E-10

7.33E-10

7.30E-10

1.46E-09

1.52E-09

0.020

1.43E-09

1.60E-09

2.03E-09

2.99E-09

6.01E-09

2.73E-09

0.030

4.67E-09

5.54E-09

8.68E-09

1.59E-08

4.34E-08

1.54E-08

0.040

1.04E-08

1.69E-08

2.97E-08

5.04E-08

1.16E-07

3.91E-08

0.050

2.22E-08

4.44E-08

6.55E-08

1.00E-07

1.98E-07

5.33E-08

0.060

9.52E-08

9.13E-08

1.12E-07

1.45E-07

2.95E-07

1.18E-07

0.070

1.77E-06

5.99E-07

6.23E-07

7.86E-07

1.32E-06

1.59E-06

0.080

7.98E-06

3.47E-06

3.84E-06

4.10E-06

6.31E-06

8.62E-06

0.100

3.13E-05

2.29E-05

2.23E-05

2.20E-05

2.45E-05

3.86E-05

0.150

7.88E-05

7.63E-05

6.73E-05

6.61E-05

8.02E-05

1.42E-04

0.200

1.16E-04

1.10E-04

9.70E-05

1.11E-04

1.54E-04

2.85E-04

0.300

2.20E-04

1.93E-04

2.07E-04

2.60E-04

3.65E-04

5.84E-04

0.400

2.75E-04

2.52E-04

2.68E-04

3.29E-04

4.32E-04

6.53E-04

0.500

3.30E-04

3.09E-04

3.27E-04

3.97E-04

5.02E-04

7.44E-04

0.600

3.86E-04

3.65E-04

3.86E-04

4.64E-04

5.83E-04

9.22E-04

0.800

5.06E-04

4.75E-04

5.08E-04

6.01E-04

8.38E-04

1.74E-03

1.000

6.42E-04

5.81E-04

6.52E-04

7.68E-04

1.31E-03

3.26E-03

1.500

1.11E-03

8.95E-04

1.44E-03

1.77E-03

4.16E-03

9.94E-03

2.000

1.81E-03

1.50E-03

3.19E-03

4.04E-03

8.66E-03

1.56E-02

3.000

3.79E-03

3.35E-03

7.21E-03

8.73E-03

1.56E-02

2.58E-02

4.000

6.14E-03

6.12E-03

1.14E-02

1.33E-02

2.04E-02

3.56E-02

5.000

8.30E-03

9.21E-03

1.53E-02

1.84E-02

2.41E-02

4.54E-02

6.000

1.05E-02

1.24E-02

1.89E-02

2.38E-02

2.79E-02

5.61E-02

8.000

1.62E-02

1.84E-02

2.43E-02

3.56E-02

3.97E-02

8.33E-02

1432
1433

56

Effective dose rate (nSv h-1 Bq -1 m2 )DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1439
1440
1441
1442
1443

Soil contamination, photon sources at 0.0 mfp

10-2

10-3
Adult
15 years
10 years
5 years
1 year0 yearsh*(10)

10-4

10-5

10-6
0.01

0.1

1

10

Photon energy (MeV)
Fig. 6.2. Effective dose rate coefficients for monoenergetic photon sources distributed at thesurface as a ground plane source and the corresponding ambient dose equivalent rate, ℎ̇∗ (10),at 1 m above the ground.

Effective dose rate (nSv h-1 Bq -1 m2 )

1434
1435
1436
1437
1438

10-1

10-2

Soil contamination, photon sources at 0.2 mfp
10-3

Adult
15 years
10 years
5 years
1 year0 yearsh*(10)

10-4

10-5

10-6
0.01

0.1

1

10

Photon energy (MeV)
Fig. 6.3. Effective dose rate coefficients for monoenergetic photon sources distributed at a
depth of 0.2 mean free paths in the soil and the corresponding ambient dose equivalent rate,ℎ̇∗ (10), at 1 m above ground.
57

Effective dose rate (nSv h-1 Bq -1 m2 )DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1448
1449
1450
1451
1452

Soil contamination, photon sources at 1.0 mfp

10-3

10-4

10

Adult
15 years
10 years
5 years
1 year0 yearsh*(10)

-5

10-6

10-7
0.01

0.1

1

10

Photon energy (MeV)
Fig. 6.4. Effective dose rate coefficients for monoenergetic photon sources distributed at a
depth of 1 mean free paths in the soil and the corresponding ambient dose equivalent rate,ℎ̇∗ (10), at 1 m above ground.

Effective dose rate (nSv h-1 Bq -1 m2 )

1444
1445
1446
1447

10-2

10-3

10-4
Adult
15 years
10 years
5 years
1 year0 yearsh*(10)

10-5

10-6

10-7

Soil contamination, photon sources at 2.5mfp
10-8
0.01

0.1

1

10

Photon energy (MeV)
Fig. 6.5. Effective dose rate coefficients for monoenergetic photon sources distributed at a
depth of 2.5 mean free paths in the soil and the corresponding ambient dose equivalent rate,ℎ̇∗ (10), at 1 m above ground.
58

Effective dose rate (nSv h-1 Bq -1 m2 )DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

10-4

10-5

10-7

10-8

Soil contamination, photon sources at 4.0 mfp
10

-9

0.01

1458
1459
1460
1461
1462
1463

0.1

1

10

Photon energy (MeV)
Fig. 6.6. Effective dose rate coefficients for monoenergetic photon sources distributed at a
depth of 4 mean free paths in the soil and the corresponding ambient dose equivalent rate,ℎ̇∗ (10), at 1 m above ground.

Effective dose rate (nSv h-1Bq-1m3 )

1453
1454
1455
1456
1457

Adult
15 years
10 years
5 years
1 year0 yearsh*(10)

10-6

100
10-1

Soil contamination, electron sources at 0.0 mfp

10-2
10-3
10-4
10-5

Adult
15 years
10 years
5 years
1 year0 years

10-6
10-7
10-8
10-9
10-10
10-11
0.01

0.1

1

10

Electron energy (MeV)
Fig. 6.7. Effective dose rate coefficients for monoenergetic electron sources distributed at thesurface as a ground plane source.
(102) Fig. 6.8 shows the variation of effective dose rate coefficients for an adult as afunction of mean free path (mfp) of photons in soil.
59

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1464
1465

1466
1467
1468
1469
1470
1471
1472

Fig. 6.8. Effective dose rate coefficients for the adult phantom as a function of mean free pathin the soil, for source energy of 0.5 and 0.05 MeV photons. The bullets indicate the depths forwhich calculations were explicitly performed. The star indicates the effective dose rate at
depth of 5 cm, evaluated through interpolation.

1473

6.3. Dose rate coefficients for air submersion

1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495

(103) The air submersion exposure geometry involves an individual standing in a large
volume of uniformly contaminated air. It is assumed that the individual is standing on an
uncontaminated flat surface of infinite area. The source for the submersion dose calculations
is a semi-infinite cloud containing a uniformly-distributed monoenergetic photon and electron
emitter surrounding a human phantom standing on the soil at the air-ground interface. Fig. 5.5(right) illustrates the irradiation geometry for the organ equivalent dose calculations.
(104) As for ground planar sources, organ equivalent dose rate coefficients in eachphantom are computed using the environmental photon and electron data as recorded to theexternal ASCII file. It should be noted that for electron sources, the electrons do not only startfrom the surface of the coupling cylinder but also from within the volume of the cylinder,
which is filled with contaminated air. Transport calculations for cylinder-surface source andcylinder-volume sources were performed separately.
(105) The effective dose rate coefficients of monoenergetic sources distributed uniformly
in the atmosphere are shown in Tables 6.7 and 6.8 and in Fig. 6.9 and Fig. 6.10 as a functionof photon and electron energies, respectively. A total of 25 source energies were selectedfrom 0.01 to 8 MeV. The unit of the dose rate coefficients is nSv h-1 Bq-1 m3. The air kerma
and ambient dose equivalent rate coefficients at a height of 1 m above the ground are also
listed in Table 6.7 for photon sources. The supplementary data of the organ equivalent dose
rate coefficients can be found at the electronic data accompanying this report. Fig. 6.9 shows
also the ℎ̇∗ (10), and demonstrates that the conservative approach is retained (i.e. the ambient
dose equivalent is higher than the effective dose for all phantoms considered).

60

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1496
1497

Table 6.7. Effective dose rate, ambient dose equivalent rate and air kerma rate coefficients formonoenergetic photons and air submersion.
ℎ∗̇ (10)
EnergyEffective dose rate coefficient
-1

(MeV)

-1

3

(nSv h Bq m )(nGy h-1
Bq-1 m3)

Adult

15 yr

10 yr

5 yr

1 yr

Newborn

0.010

2.10E-05

2.04E-05

2.81E-05

2.84E-05

3.32E-05

3.70E-05

2.50E-05

3.12E-03

0.015

8.54E-05

9.79E-05

1.40E-04

1.44E-04

1.58E-04

1.71E-04

1.13E-03

4.46E-03

0.020

2.31E-04

2.81E-04

3.25E-04

3.71E-04

3.74E-04

5.88E-04

3.18E-03

5.33E-03

0.030

9.72E-04

1.14E-03

1.25E-03

1.53E-03

1.70E-03

2.20E-03

6.61E-03

6.31E-03

0.040

2.26E-03

2.48E-03

2.66E-03

3.18E-03

3.54E-03

4.14E-03

1.08E-02

8.02E-03

0.050

3.76E-03

3.99E-03

4.29E-03

5.00E-03

5.56E-03

6.04E-03

1.30E-02

8.48E-03

0.060

5.19E-03

5.65E-03

5.98E-03

6.71E-03

7.39E-03

7.84E-03

1.68E-02

1.05E-02

0.070

6.92E-03

7.56E-03

7.85E-03

8.62E-03

9.47E-03

9.82E-03

2.06E-02

1.26E-02

0.080

8.65E-03

9.42E-03

9.74E-03

1.05E-02

1.15E-02

1.18E-02

2.41E-02

1.45E-02

0.100

1.11E-02

1.19E-02

1.27E-02

1.35E-02

1.46E-02

1.54E-02

2.87E-02

1.75E-02

0.150

1.95E-02

2.08E-02

2.17E-02

2.28E-02

2.38E-02

2.52E-02

4.54E-02

2.90E-02

0.200

2.77E-02

2.97E-02

3.07E-02

3.23E-02

3.31E-02

3.51E-02

6.18E-02

4.10E-02

0.300

4.36E-02

4.63E-02

4.76E-02

5.06E-02

5.14E-02

5.45E-02

9.20E-02

6.42E-02

0.400

5.91E-02

6.19E-02

6.38E-02

6.80E-02

6.94E-02

7.36E-02

1.19E-01

8.66E-02

0.500

7.48E-02

7.74E-02

7.98E-02

8.52E-02

8.75E-02

9.27E-02

1.45E-01

1.09E-01

0.600

9.10E-02

9.37E-02

9.62E-02

1.03E-01

1.06E-01

1.12E-01

1.71E-01

1.31E-01

0.800

1.27E-01

1.32E-01

1.33E-01

1.40E-01

1.46E-01

1.54E-01

2.27E-01

1.79E-01

1.000

1.64E-01

1.73E-01

1.73E-01

1.81E-01

1.87E-01

1.98E-01

2.83E-01

2.29E-01

1.500

2.58E-01

2.72E-01

2.70E-01

2.82E-01

2.87E-01

3.04E-01

4.19E-01

3.49E-01

2.000

3.55E-01

3.72E-01

3.68E-01

3.83E-01

3.86E-01

4.06E-01

5.52E-01

4.68E-01

3.000

5.51E-01

5.73E-01

5.68E-01

5.92E-01

5.85E-01

6.08E-01

8.11E-01

7.02E-01

4.000

7.52E-01

7.76E-01

7.73E-01

8.06E-01

7.84E-01

8.08E-01

1.06E+00

9.34E-01

5.000

9.57E-01

9.84E-01

9.83E-01

1.03E+00

9.86E-01

1.01E+00

1.31E+00

1.16E+00

6.000

1.17E+00

1.20E+00

1.20E+00

1.25E+00

1.19E+00

1.22E+00

1.56E+00

1.40E+00

8.000

1.59E+00

1.65E+00

1.64E+00

1.70E+00

1.62E+00

1.66E+00

2.06E+00

1.87E+00

1498
1499

61

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1500

Table 6.8. Effective dose rate coefficients for monoenergetic electrons and air submersion.
EnergyEffective dose rate coefficient(MeV)(nSv h-1 Bq-1 m3)

0.010

Adult
3.91E-09

15 yr
1.37E-09

10 yr
1.57E-09

5 yr
5.85E-10

1 yr
6.93E-10

Newborn
4.46E-10

0.015

9.15E-09

3.88E-09

4.51E-09

1.88E-09

2.77E-09

1.28E-09

0.020

2.06E-08

9.19E-09

1.14E-08

3.87E-09

8.78E-09

2.48E-09

0.030

6.31E-08

3.77E-08

3.78E-08

3.23E-08

5.28E-08

4.30E-08

0.040

1.63E-07

1.18E-07

1.10E-07

1.85E-07

1.43E-07

1.23E-07

0.050

3.34E-07

2.60E-07

3.00E-07

4.19E-07

3.23E-07

2.82E-07

0.060

5.99E-07

4.83E-07

5.45E-07

7.14E-07

6.49E-07

6.00E-07

0.070

1.82E-06

1.60E-06

1.72E-06

1.96E-06

2.09E-06

1.91E-06

0.080

5.57E-06

5.84E-06

6.11E-06

6.11E-06

6.21E-06

5.55E-06

0.100

2.84E-05

3.00E-05

3.08E-05

3.04E-05

3.02E-05

2.85E-05

0.150

1.16E-04

1.30E-04

1.28E-04

1.27E-04

1.31E-04

1.32E-04

0.200

2.51E-04

2.60E-04

2.57E-04

2.64E-04

2.70E-04

2.68E-04

0.300

5.77E-04

5.81E-04

5.73E-04

5.79E-04

5.78E-04

5.34E-04

0.400

8.24E-04

8.10E-04

8.03E-04

7.90E-04

7.90E-04

7.76E-04

0.500

1.09E-03

1.05E-03

1.05E-03

1.02E-03

1.02E-03

1.05E-03

0.600

1.38E-03

1.31E-03

1.35E-03

1.28E-03

1.31E-03

1.55E-03

0.800

2.04E-03

1.86E-03

1.99E-03

1.90E-03

2.22E-03

3.26E-03

1.000

3.06E-03

2.56E-03

3.14E-03

3.08E-03

3.96E-03

5.90E-03

1.500

6.70E-03

5.23E-03

8.20E-03

8.50E-03

1.20E-02

1.66E-02

2.000

1.21E-02

1.08E-02

1.64E-02

1.75E-02

2.54E-02

3.32E-02

3.000

2.65E-02

2.81E-02

4.90E-02

4.65E-02

6.07E-02

7.08E-02

4.000

4.73E-02

5.51E-02

8.44E-02

8.31E-02

9.56E-02

1.18E-01

5.000

7.36E-02

9.02E-02

1.24E-01

1.26E-01

1.33E-01

1.74E-01

6.000

1.05E-01

1.32E-01

1.70E-01

1.73E-01

1.77E-01

2.40E-01

8.000

1.77E-01

2.26E-01

2.95E-01

2.74E-01

3.05E-01

4.00E-01

1501
1502

62

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE(106) Regarding the age-dependency of the coefficients, it was observed that in general,
the smaller the body mass of the phantom, the higher the organ and effective dose due thesmaller amount of body shielding of internal organs in the younger and smaller reference
phantoms. The difference in effective dose between the adult and the newborn is highest at
0.01 MeV photon energy (150%), while it is less than 40% above a photon energy of 0.07
MeV.
Effective dose rate (nSv h-1 Bq -1 m3 )

1503
1504
1505
1506
1507
1508

1514
1515
1516
1517

Air submersion, photon sources

100
10-1
10-2

Adult
15 years
10 years
5 years
1 year0 yearsh*(10)

10-3
10-4
10-5
0.01

0.1

10

1

Photon energy (MeV)

Fig. 6.9. Effective dose rate coefficients for monoenergetic photon sources distributed
uniformly in the atmosphere as a function of photon energy and ambient dose equivalentℎ̇∗ (10) at 1 m above ground.
Effective dose rate (nSv h-1Bq-1m3 )

1509
1510
1511
1512
1513

101

101
100

Air submersion, electron sources

10-1
10-2
10-3
10-4
10-5

Adult
15 years
10 years
5 years
1 year0 years

-6

10

10-7
10-8
10-9
10-10
0.01

1

0.1

10

Electron energy (MeV)

Fig. 6.10. Effective dose rate coefficients for monoenergetic electron sources distributed
uniformly in the atmosphere as a function of electron energy.

63

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1518

6.4. Dose rate coefficients for water immersion

1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532

(107) Dose rate coefficients for water immersion were calculated under the assumptionthat an individual is completely immersed in an infinite volume of uniformly contaminatedwater. For the water photon exposure, the whole spherical geometry is sampled, including
those voxels in the phantom matrix outside the body that are identified as water.
(108) Contributors to the organ equivalent doses from electron sources in the water
immersion geometry are the primary electrons emitted from the water near the body surface
and the bremsstrahlung photons generated by electron interactions in water.
(109) Calculations were performed for 25 monoenergetic sources of photons and electrons
ranging from 0.01 to 8 MeV and for all male and female adult and paediatric phantoms.
Tables 6.9 and 6.10 present the evaluated coefficients of effective dose rate for photon andelectron sources, respectively, distributed uniformly in water, while Fig. 6.11 and Fig. 6.12
depict those same data as a function of photon and electron energies, respectively. The data
are given in units of nSv h-1 Bq-1 m3.

64

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1533
1534

Table 6.9. Effective dose rate coefficients for monoenergetic photon sources and water
immersion.
EnergyEffective dose rate coefficient (nSv h-1 Bq-1 m3)
(MeV)
Adult
15 yr
10 yr
5yr
1yr
newborn
0.010
3.62E-08
2.87E-08
4.91E-08
4.43E-08
5.14E-08
7.66E-08
0.015

1.64E-07

1.86E-07

2.89E-07

3.00E-07

3.41E-07

4.67E-07

0.020

4.95E-07

5.88E-07

7.19E-07

9.08E-07

9.11E-07

1.27E-06

0.030

2.18E-06

2.45E-06

2.78E-06

3.81E-06

4.04E-06

5.13E-06

0.040

5.01E-06

5.77E-06

6.60E-06

8.10E-06

9.07E-06

1.07E-05

0.050

8.53E-06

9.66E-06

1.06E-05

1.29E-05

1.46E-05

1.64E-05

0.060

1.21E-05

1.36E-05

1.50E-05

1.77E-05

1.97E-05

2.24E-05

0.070

1.57E-05

1.75E-05

1.92E-05

2.24E-05

2.48E-05

2.79E-05

0.080

1.93E-05

2.13E-05

2.33E-05

2.69E-05

2.98E-05

3.32E-05

0.100

2.66E-05

2.85E-05

3.12E-05

3.57E-05

3.92E-05

4.35E-05

0.150

4.32E-05

4.64E-05

4.97E-05

5.59E-05

6.03E-05

6.61E-05

0.200

6.00E-05

6.37E-05

6.80E-05

7.59E-05

8.18E-05

8.92E-05

0.300

9.41E-05

9.92E-05

1.05E-04

1.17E-04

1.25E-04

1.36E-04

0.400

1.29E-04

1.36E-04

1.43E-04

1.58E-04

1.69E-04

1.83E-04

0.500

1.65E-04

1.72E-04

1.82E-04

1.99E-04

2.13E-04

2.30E-04

0.600

2.01E-04

2.10E-04

2.21E-04

2.41E-04

2.57E-04

2.76E-04

0.800

2.74E-04

2.84E-04

2.98E-04

3.23E-04

3.40E-04

3.65E-04

1.000

3.62E-04

3.76E-04

3.93E-04

4.25E-04

4.46E-04

4.75E-04

1.500

5.71E-04

5.87E-04

6.12E-04

6.57E-04

6.84E-04

7.22E-04

2.000

7.82E-04

8.03E-04

8.34E-04

8.90E-04

9.24E-04

9.71E-04

3.000

1.21E-03

1.25E-03

1.29E-03

1.36E-03

1.41E-03

1.47E-03

4.000

1.66E-03

1.70E-03

1.76E-03

1.85E-03

1.90E-03

1.99E-03

5.000

2.12E-03

2.18E-03

2.25E-03

2.35E-03

2.40E-03

2.51E-03

6.000

2.60E-03

2.67E-03

2.75E-03

2.87E-03

2.91E-03

3.04E-03

8.000

3.62E-03

3.70E-03

3.82E-03

3.99E-03

3.98E-03

4.14E-03

1535
1536

65

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1537
1538

Table 6.10. Effective dose rate coefficients for monoenergetic electron sources and water
immersion.
EnergyEffective dose rate coefficient (nSv h-1 Bq-1 m3)
Adult
15 yr
10 yr
5yr
1yr
Newborn
(MeV)
0.010

2.97E-12

1.31E-12

1.13E-12

5.15E-13

4.72E-13

5.26E-13

0.015

1.08E-11

4.08E-12

3.92E-12

1.77E-12

1.66E-12

1.76E-120.020

2.90E-11

1.30E-11

1.45E-11

5.95E-12

1.37E-11

1.39E-11

0.030

9.75E-11

6.09E-11

7.18E-11

8.71E-11

8.61E-11

1.11E-10

0.040

2.68E-10

2.01E-10

2.60E-10

3.32E-10

3.13E-10

4.11E-10

0.050

5.92E-10

4.96E-10

6.28E-10

8.01E-10

7.60E-10

9.71E-10

0.060

1.13E-09

9.71E-10

1.19E-09

1.56E-09

1.46E-09

1.97E-09

0.070

2.91E-09

2.54E-09

2.89E-09

3.54E-09

3.37E-09

4.17E-09

0.080

8.78E-09

8.04E-09

8.56E-09

9.52E-09

9.32E-09

1.03E-08

0.100

4.04E-08

3.88E-08

4.02E-08

4.10E-08

4.20E-08

4.35E-08

0.150

1.84E-07

1.80E-07

1.83E-07

1.85E-07

1.87E-07

1.93E-07

0.200

3.52E-07

3.45E-07

3.51E-07

3.54E-07

3.58E-07

3.67E-07

0.300

7.07E-07

6.97E-07

7.07E-07

7.09E-07

7.19E-07

7.38E-07

0.400

1.09E-06

1.05E-06

1.08E-06

1.08E-06

1.11E-06

1.15E-06

0.500

1.51E-06

1.43E-06

1.50E-06

1.49E-06

1.53E-06

1.64E-06

0.600

1.99E-06

1.84E-06

1.97E-06

1.95E-06

2.01E-06

2.27E-06

0.800

3.11E-06

2.77E-06

3.15E-06

3.09E-06

3.50E-06

4.33E-06

1.000

4.50E-06

3.92E-06

4.79E-06

4.80E-06

6.17E-06

8.24E-06

1.500

1.01E-05

8.44E-06

1.24E-05

1.42E-05

2.18E-05

3.04E-05

2.000

1.83E-05

1.61E-05

2.66E-05

2.96E-05

4.70E-05

6.35E-05

3.000

4.55E-05

4.89E-05

7.66E-05

8.04E-05

1.09E-04

1.44E-04

4.000

8.29E-05

9.41E-05

1.43E-04

1.47E-04

1.82E-04

2.45E-04

5.000

1.32E-04

1.52E-04

2.18E-04

2.29E-04

2.68E-04

3.66E-04

6.000

1.93E-04

2.23E-04

3.04E-04

3.27E-04

3.68E-04

5.07E-04

8.000

3.56E-04

4.06E-04

5.23E-04

5.70E-04

6.23E-04

8.46E-04

1539
1540
1541

66

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

Effective dose (nSv h-1Bq-1 m3)

10-2

Water immersion, photon sources

10-3
10-4
10-5
Adult
15 years
10 years
5 years
1 year0 years

10-6
10-7
10-8
0.01

1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559

1

10

Photon energy (MeV)

Fig. 6.11. Effective dose rate coefficients for monoenergetic photon sources distributed
uniformly in the water (i.e. water immersion).
Effective dose rate (nSv h-1Bq-1m3 )

1542
1543
1544
1545
1546

0.1

10-2
10-3

Water immersion, electron sources

10-4
10-5
10-6
10-7
10-8

Adult
15 years
10 years
5 years
1 year0 years

-9

10

10-10
10-11
10-12
10-13
0.01

0.1

1

10

Electron energy (MeV)

Fig. 6.12. Effective dose rate coefficients for monoenergetic electron sources distributed
uniformly in the water (i.e. water immersion).
(110) Fig. 6.13 shows the effective dose rate of the newborn for monoenergetic electrons,
together with the skin equivalent dose multiplied by tissue weighting factor, 0.01. The skinequivalent dose has been computed with the polygon mesh-type phantoms in order to evaluate
the dose at the radiosensitive region of the epidermis which is considered to be 50 to 100 μm
below the skin surface (see Annex B). It can be seen, that up to about 1 MeV, the dose to theskin is the main contributor to the effective dose for environmental electron exposures.
(111) The age-dependency of the effective dose coefficients is similar to the case of
immersion to contaminated air, the effective dose for newborns being up to 150% higher thanfor adults, for photon energies of 0.02 MeV.
67

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

Dose coefficient rate (nSv h-1Bq-1m3)

1560
1561

10-2
10-3
-4

10

Water immersion, electron source
Newborn

10-5
10-6
10-7
10-8
10-9
10-10
10-11

Effective dose
Skin equivalent dose x 0.01

-12

10

10-13
0.01

0.1

1

10

Electron energy (MeV)

1562
1563
1564
1565
1566

Fig. 6.13. Comparison of effective and skin dose rate coefficients for monoenergetic electrons
distributed uniformly in the water (i.e. water immersion), for a newborn phantom. For
comparison’s sake, the skin dose rate has been multiplied by 0.01 i.e. the wT of skin.

1567

6.5. Verification of the calculations (spot-checks)

1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585

(112) The environmental fields specific for the exposure situations selected as being
representative of the most common exposure scenarios were calculated specifically for thisreport by Daiki Satoh, Japan Atomic Energy Agency (JAEA), a member of the Task Group,
using the Monte Carlo code PHITS (see section 4). The organ equivalent dose calculations for
all geometries, particles and phantoms were also performed by D. Satoh with PHITS – seeprevious sections. Separate calculations were performed for skin dosimetry by Yeon Soo Yeom
(Hanyang University) using GEANT4 and the mesh format of the phantoms – see Annex B on
skin dosimetry. The reference coefficients tabulated in this report have been evaluated by theabove data after smoothing and least squares polynomial fitting.
(113) For quality assurance purposes, several organ equivalent dose data sets have been
re-calculated by different members of the Task Group using the same environmental fields
and the same reference computational phantoms but different radiation transport codes. The
Monte Carlo codes used were the GEANT4 -YS Yeom (Hanyang University), EGSnrc - H
Schlattl (Helmholtz Zentrum München, HMGU) and MCNPX - SJ Yoo (Korean Institute of
Nuclear Safety, KINS), MCNP6 - J Jansen (Public Health England, PHE), MCNPX – C Lee,
National Cancer Institute, NCI), Visible Monte Carlo - J Hunt (Instituto de Radioproteção e
Dosimetria, IRD). This section describes briefly the Monte Carlo calculations performed forthe spot-checks.
68DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1586

6.5.1. GEANT4 (user Hanyang University)

1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617

(114) The GEANT4 code is a general-purpose Monte Carlo code, which was developed in
the C++ programming language, exploiting software engineering and object-oriented
technology (Agostinelli et al., 2003). Since the first public release in 1998, the GEANT4 code
has been improved and maintained by the GEANT4 collaboration of various international
research groups (http://geant4.cern.ch/). The GEANT4 code can simulate a large set ofparticles, covering a wide energy range from 100 eV to 10 TeV or, for some particles, 10 PeV(Allison et al., 2016). It is widely used in various applications including radiation dosimetry,
medical application, space science and accelerator physics.
(115) GEANT4 Version 10.2 was used for the calculations of this report for the spotcheck to validate organ equivalent dose rate coefficients for soil contamination, photon andelectron sources. The reference voxel phantoms were implemented in the GEANT4 code byusing the G4VNestedParameterisation class, which, among the GEANT4 classes, provides thebest features for implementation of voxel geometry (Schümann et al., 2012). The physics
library of the G4EmLivermorePhysics, including EPDL97 (Cullen et al., 1997), EEDL
(Perkins et al., 1991) and EADL (Perkins et al., 1997), was used to simulate photons andelectrons. A secondary production cut value for all the particles in all the media was set to arange of 1 µm for the precise simulation.
(116) Organ equivalent dose rate coefficients for monoenergetic photons and electrons(0.03–3 MeV) of some soil-contamination cases were calculated by directly using the phasespace source data as recorded on the coupling cylinder in the first step of calculation method(see 5.1). During the calculations, from the source data, a particle was randomly selected andits position and direction were rotated by an angle randomly selected between 0° and 360° on
the z-axis (i.e. the centre axis of the coupling cylinder); this approach can avoid any
undesirable direction bias at the given number of the particles in the source data, consideringthat the irradiation geometry is cylindrically symmetric.
(117) For photons, relative statistical uncertainties of the calculated organ equivalentdoses were generally below 1% for larger organs and 4% for smaller organs. For electrons
above 0.2 MeV, the uncertainties were generally below 2% for larger organs and 10% forsmaller organs, while for lower energy electrons, most of the calculated organ equivalentdoses had large statistical uncertainties, with the exceptions of the skin doses whose
uncertainties were all below 0.1%.

1618

6.5.2. MCNP6 (user PHE)

1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631

(118) The Monte Carlo N-Particle code system MCNP (Los Alamos National Laboratory(LANL), Los Alamos, NM) version 6.1 (Pelowitz, 2013a,b) has been used in Fortran 90 codeform. The source code has been patched according to Michael Lorne Fensin publication on
the MCNP-Forum at Monday 22 September 2014 to allow for convenient voxel sampling
within a lattice. In addition, a Fortran 90 source routine has been inserted to allow for thereading of the source files describing the environmental field. This source routine reads thewhole source file the first time and applies a source rotation over a sampled (random) angle
during successive file reads. The Fortran 90 code has been compiled with the Intel Fortrancompiler (Intel Corporation, Santa Clara, CA). For quality control, the executable was testedon the verification samples and differences have been verified, documented and forwarded to
Los Alamos National Laboratory.
(119) The cross-section library used was the MCPLIB04 for photons and EL03 forelectrons, both being the MCNP6 default. For all organs, except the active marrow and69

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1632
1633
1634
1635
1636
1637
1638
1639
1640
1641

endosteum, and photon exposures the organ equivalent doses are calculated without electrontransport assuming electron equilibrium, except for air submersion, where for photon energies≥ 1 MeV electron transport is performed. For all organs, the tally 6 track length heating
number estimator, i.e. a track length estimator with an internally calculated fluence-to-dose
function, is used to derive the absorbed dose; an exception is the calculation of active bonemarrow and endosteum absorbed dose rate coefficients for photon exposures, where the doseenhancement factors are used to compensate for the lack of electron equilibrium and the tally
4 track length estimator is modified by a fluence-to-dose response function (see Annex A).
The validation calculations performed were for air and water immersion, photon and electron
sources and for all ICRP reference paediatric phantoms.

1642

6.5.3. MCNPX (user KINS)

1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661

(120) The Monte Carlo particle transport code MCNPX 2.7.0 (Pelowitz, 2011) was used
together with the cross section library MCNPLIB04 and El03 for calculating the absorbed
doses to the organs of the ICRP adult and paediatric reference phantoms due to unit source
intensity of specified energies of photons for air submersion and water immersion exposure
situations. For the specified photon energies, 25 energy bins are used for the range of 0.01 to
10 MeV. Absorbed doses for organs and tissues were calculated by applying the F6 tally in
MCNPX code. The transport calculations were performed for the source volume within theconverging of distances (Yoo et al., 2013a,b), which are determined by a simplified
calculation model.
(121) To resolve the poor statistics in small organs (e.g. the thymus and the lymph nodes),an approach, called equivalent dose ratio method (Yoo et al., 2013a), was applied byassuming that the energy spectrum of photons entering the body would not significantly
change with the geometrical ranges beyond a few mean free paths. The ratios of the absorbed
doses for small organs to those received by the muscle (reference organ) were calculated at 50
m radius (reference distance) and for each energy bin. After confirming that the deviations of
the ratios are within 10% while the radius of the air volume varies, these ratios were used toobtain doses to small organs.
(122) The validation calculations performed were for air and water immersion, photon
beams and for all ICRP reference paediatric phantoms.

1662

6.5.4. MCNPX (user NCI)

1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675

(123) The Monte Carlo N-Particle eXtended (MCNPX) Version 2.7.0 (Pelowitz, 2011)
was employed to the verification of the calculations of organ equivalent dose coefficients at
the National Cancer Institute. The verification was focused on the soil contamination with thedepth of 0.0 mfp (i.e. surface contamination) for 13 photon energy bins ranging from 0.01 to 5
MeV. The newborn and 15-year-old ICRP paediatric phantoms were included in theverification process. Organ equivalent dose rate coefficients were calculated for over 30
organs and tissues and delivered to JAEA for comparison with the data from PHITS code.
(124) Source data for soil contamination computed at JAEA by PHITS, called phase space
data, was delivered to the NCI. Since MCNPX writes and reads external source definition
through the Surface Source Write/Read (SSW/SSR) routines, the source data from PHITS
were not directly compatible with MCNPX. The source data from PHITS in ASCII format
were converted into the binary format using an in-house script according to the description of
the SSW routine in MCNPX.

70

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1676
1677
1678
1679
1680
1681

(125) The cross-section library, mcplib04 and el03, were adopted for photons andelectrons, respectively, in the verification process. A total of 500 million particle histories
were used to achieve acceptable statistical errors. Default energy cut off, 0.001 MeV, wasused for both photon and electron transport. Absorbed dose to organs and tissues wascalculated by using F8 energy deposition tally. The high-performance computing server
installed at the NCI was utilized to facilitate the large amount of Monte Carlo calculations.

1682

6.5.5. EGSnrc (user HMGU)

1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710

(126) For calculations of photon organ equivalent dose coefficients a code developed
specifically for organ equivalent dose calculations (Schlattl et al., 2012) has been used,
employing the electron-gamma-shower code system EGSnrc Version v4-2-3-1 (Kawrakow etal., 2009). EGSnrc is an extended and improved version of EGS4 (Nelson et al., 1985),
maintained by the National Research Council of Canada (NRC). The transport of photons andelectrons can be simulated for particle kinetic energies from a few keV up to several hundred
GeV, although simulations performed in this study were made only for photons in the energy
range of 0.01 to 8 MeV.
(127) For photon transport, bound Compton scattering and secondary photo-electrons
from K, L, and M shells are considered for all energies. In both cases, resulting fluorescenceor Auger and Coster-Kronig electrons are followed. The input data for photon cross sections
agree with those of the XCOM database (Berger and Hubbell, 1987).
(128) For the calculations performed for this report, photon transport is terminated when
the photon energy falls below 2 keV. Secondary electrons are followed until their kinetic
energy drops below 20 keV.
(129) The number of histories followed varied between 450 million at 0.01 MeV to 100
million at 8 MeV, resulting in coefficients of variance for most organs below 1%, and only in
exceptions reaches up to 4% (e.g. at low energies for gall bladder).
(130) By assuming rotational symmetry, the phase-space source data of the coupling
cylinder was converted into a discrete probability density function (φ(E, h, sinϑ)) with E
being the particle energy, h its source position on the cylinder and ϑ its direction relative tothe horizontal plane. At the lids of the cylinder the probability density function was φ(E,sinϑ).
(131) The source sampling in the EGSnrc user code was performed by the cumulative
density function obtained from the probability density function and enforcing rotational
symmetry.
(132) The validation calculations performed were for air submersion and groundcontamination, photon beams and the ICRP adult reference phantoms.

1711

6.5.6. Visible Monte Carlo (user IRD)

1712
1713
1714
1715
1716
1717
1718
1719
1720

(133) Visible Monte Carlo (VMC) (Hunt et al., 2004) has been developed at the Institutode Radioproteção e Dosimetria from 1994 to the present date. VMC transports photons,
electrons, alpha particles and protons through voxel and general geometrical structures.
Bremsstrahlung production and transport is not considered for low Z materials. The photon
energy range considered for the spot check calculations was 0.03 to 3 MeV. VMC benefits
from an extensive graphical interface that shows all aspects of the simulated geometry andalso the photon interactions with the environment and the phantom.
(134) VMC version March 2016 was used for the spot-check calculations to validate
organ equivalent dose coefficients for water contamination and the adult phantoms. The cross71DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1721
1722
1723
1724
1725
1726

section library used is the NIST XCOM database (Berger and Hubbell, 1987) and the size of
the water sphere considered for each photon energy was based on the maximum distancetravelled by the simulation of the transport of 108 photons in water. The photon transport is
terminated when the photon suffers a photoelectric effect. The statistical uncertainties of thecalculated organ equivalent doses were estimated to be below 1% for the larger organs andbelow 5% for smaller organs.

1727
1728

6.5.7. Comparison of dose rate coefficients calculated with different codes andcomparisons with other work

1729
1730
1731
1732
1733
1734
1735
1736
1737

(135) Fig. 6.14 shows the effective dose for monoenergetic photons, for the various agephantoms and ground plane surface source (left) and air submersion (right), as estimated bydifferent calculators and codes. As it can be seen, the agreement of computed dose rate
coefficient by the different Monte Carlo codes is within 10% and in most cases below 4%.
Also shown are values of effective dose, as given in Federal Guidance Report (FGR) of the
USA (Bellamy et al., 2018). Note that the latter data have been obtained for environmental
field data estimated by Bellamy et al using stylized hermaphroditic models of the ICRP
reference individuals (Cristy and Eckerman, 1987; Han et al., 2006).

1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750

Fig. 6.14. Effective dose for photon ground plane surface source (left) and air submersion(right), as estimated by different calculators and codes. The PHITS data set shows the data
after smoothing. For better visibility, the data were plotted multiplied by a factor of 10-105.
FGR 15 indicates the Federal Guidance Report (Bellamy et al., 2018).
(136) Fig. 6.15 shows selected values of organ equivalent dose rates for a ground planarsource emitting monoenergetic electrons, for the male adult phantom, as computed by PHITS
and GEANT4. It can be seen, that, as mentioned in section 6.1, the values which contribute to
the effective dose less than 1% are set to zero. Fig. 6.16 shows organ equivalent dose rates
for the 15-year-old male phantom and photons, as computed by MCNPX and PHITS forground planar source emitting monoenergetic photons. Similarly, Fig. 6.17 and Fig. 6.18

72

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

Equivalent dose rate (nSv h-1Bq-1 m2)

show organ equivalent dose rate coefficients for air submersion and water submersion,respectively, and photons.
Equivalent dose rate (nSv h-1Bq-1 m2)

10-1
10-2

Soil contamination, electron sources at 0.0 mfp
Adult male, R-marrow

10-3
10-4
10-5
10-6
10-7

PHITS
GEANT4

10-8
10-9
0.01

1753

0.1

1

10

100
10-2
10-3
10-4
10-5
10-6
10-7
10-8

Equivalent dose rate (nSv h-1Bq-1 m2)

10-4

Soil contamination, electron sources at 0.0 mfp
Adult male, Liver

10-5
10-6
10-7
10-8
10-9

PHITS
GEANT4

10-10
10-11
0.01

0.1

1

PHITS
GEANT4

10-9
10-10
10-11
0.01

0.1

1

10

Electron energy (MeV)

10-2
10-3

Soil contamination, electron sources at 0.0 mfp
Adult male, Testes

10-1Electron energy (MeV)
Equivalent dose rate (nSv h-1Bq-1 m2)

1751
1752

10

10-2
10-3

Soil contamination, electron sources at 0.0 mfp
Adult male, Brain

10-4
10-5
10-6
10-7
PHITS
GEANT4

10-8
10-9
0.01

0.1

1

10

1754
1755
1756
1757
1758

Fig. 6.15. Organ equivalent doses for red bone marrow, testes, liver and brain of the adultmale phantom for a ground plane source emitting electrons, as calculated by PHITS and
GEANT4.

1759
1760
1761
1762
1763
1764

Fig. 6.16. Organ equivalent doses for the 15-year-old male phantom, as calculated by PHITS
and MCNP, for ground contamination on the surface (photons). The asterisks and open
squares indicate calculations made at the Korean Institute of Nuclear Safety and Public HealthElectron energy (MeV)Electron energy (MeV)73

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1765
1766

England, respectively (Vertical lines indicate that data at lower energies have been set tozero).

1767
1768
1769
1770
1771
1772
1773
1774

Fig. 6.17. Organ equivalent doses for the 15-year-old male phantom, as calculated by PHITS
and MCNP, for submersion in contaminated air (photons). The asterisks and open squares
indicate calculations made at the Korean Institute of Nuclear Safety and Public Health
England, respectively (Vertical lines indicate that data at lower energies have been set tozero).

1775
1776
1777
1778
1779

Fig. 6.18. Organ equivalent doses for the 15-year-old male phantom, as calculated by PHITS
and MCNP, for submersion in contaminated water (photons). The asterisks and open squares
indicate calculations made at the Korean Institute of Nuclear Safety and Public Health74

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1780
1781
1782

England, respectively (Vertical lines indicate that data at lower energies have been set tozero).

1783
1784

6.6. Dose rate coefficients for monitoring - Air kerma and ambient dose
equivalent rates

1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814

(137) The ambient dose equivalent rates were compared to the effective dose rates forreference adults and reference newborn, 1-year-old, 5-year-old, 10-year-old and 15-year-old
phantoms (see Fig. 6.2 to Fig. 6.6 and Fig. 6.9), as well as to air kerma. It was shown that theambient dose equivalent sufficiently overestimates effective doses, independent of age, forplanar sources on and below the ground surface, in addition to immersion in a radioactive
cloud. As previously mentioned, opposite trends are observed for ground contamination andfor the newborn, 1-year-old, and 5-year-old phantoms at energy of 0.01 MeV where theeffective dose rate coefficient is higher than the ambient dose equivalent rate, ℎ̇∗ (10). The
difference between air kerma and effective dose was found to be smaller than the difference
between ambient dose equivalent and effective dose. For example, the air kerma is a closer
approximation to the effective dose for the environmental exposures examined.
(138) In a previous study, Saito and Petoussi-Henss (2014) presented dose coefficients
relating ambient dose equivalent rates to radionuclide density for sources exponentiallydistributed in the ground. The authors compared the ratio of ambient dose equivalent to air
kerma obtained by simulation to the ratios measured at hundreds of locations in Japan whichhave been contaminated with radioactive 137Cs, 134Cs, 131I, 110mAg and 129mTe after the
Fukushima NPP accident in 2011. Good agreement was observed in all cases.
(139) Fig. 6.19 and Fig. 6.20 show the ambient dose equivalent rates and air kerma rates at
1 m above ground, respectively, for planar sources at different depths in soil. It can be seenthat both quantities depend strongly on source soil depth and as the depth increases, both theambient dose equivalent rates and air kerma rates decrease because of the shielding effect of
the soil. The ambient dose equivalent rates at 0.2 mfp depth is about 40-70% of that at 0.0
mean free path for source energies higher than 0.015 MeV. For 1.0 mfp the reduction of theambient dose equivalent rate coefficient is more pronounced, and the ambient dose equivalentis less than 80% of that on the surface. Fig. 6.21 shows the ambient dose (rate), which is a
newly proposed operational quantity to substitute the ambient dose equivalent (see section 8.4
and ICRU Report xx (in preparation)). It can be seen that generally the values of ambient dose
rate are lower than those of ambient dose equivalent rate, and differences are more
pronounced at energies below 0.015 - 0.07 MeV. However, it was shown that ambient dose
rate also is a good estimator of effective dose for this type of field.

75

Ambient dose equivalent rate (nSv h-1Bq-1 m2)

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1815
1816
1817
1818
1819

10-1

Soil contamination, photon sources

-2

10

10-3
10-4
10-5
10

10-7
10-8
0.01

0.1

1

10

Photon energy (MeV)

Fig. 6.19. Ambient dose equivalent rates for different depths in the soil expressed as mean
free paths (mfp).

Air Kerma rate (nGy h-1Bq-1 m2)

10-1

Soil contamination, photon sources

10-2
10-3
10-4
10-5

0.0 mfp
0.2 mfp
1.0 mfp
2.5 mfp
4.0 mfp

10-6
10-7
0.01

1820
1821
1822
1823
1824
1825
1826
1827

0.0 mfp
0.2 mfp
1.0 mfp
2.5 mfp
4.0 mfp

-6

0.1

1

10

Photon energy (MeV)

Fig. 6.20. Air kerma rate at 1 m above ground, for different depths in the soil expressed asmean free paths (mfp).

76

Ambient dose rate (nSv h-1Bq-1 m2)

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1828
1829
1830
1831
1832

10-1

Soil contamination, photon sources

-2

10

10-3
10-4
10-5
0.0 mfp
0.2 mfp
1.0 mfp
2.5 mfp
4.0 mfp

10-6
10-7
10-8
0.01

0.1

1

10

Photon energy (MeV)

Fig. 6.21. Ambient dose rate, a quantity newly proposed by ICRU (ICRU, in preparation)–seesection 8.4 - for different depths in the soil expressed as mean free paths (mfp).

77

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1833
1834

7. EQUIVALENT AND EFFECTIVE DOSE RATE COEFFICIENTSFOR RADIONUCLIDES (STEP3)

1835

7.1. Coefficients for equivalent dose rate to organs and tissues

1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860

(140) Radionuclide specific equivalent dose rate coefficients, ℎ̇ 𝑇𝑇𝑆𝑆,𝑁𝑁 for tissue T, exposuremode, S, and radionuclide, N, were computed on the basis of the evaluated organ absorbed
dose rate coefficients for monoenergetic photons and electrons and the nuclear decay datacontained in Publication 107 (ICRP, 2008) using the following expression:

where R indicates the radiation type, and 𝑤𝑤𝑅𝑅 the radiation weighting factor of the radiation
type R. The summation outside a major bracket means an extension over the radiations (i.e.
photons and electrons) emitted from a radionuclide N. 𝑌𝑌𝑅𝑅,𝑖𝑖 is the yield of i-th radiation of type𝑆𝑆 (𝐸𝐸 )R having discrete energy 𝐸𝐸𝑖𝑖 emitted by a nuclear decay of the radionuclide and 𝑑𝑑̇𝑇𝑇,𝑅𝑅
𝑖𝑖 is theorgan absorbed dose rate coefficient at the energy 𝐸𝐸𝑖𝑖 for tissue, T, radiation type, R, andexposure mode, S, as provided in Section 5. The first term within the major bracket sums over𝑆𝑆 (𝐸𝐸)
all radiations emitted with discrete energies by the nuclear decay. 𝑌𝑌𝑅𝑅 (𝐸𝐸) and 𝑑𝑑̇ 𝑇𝑇,𝑅𝑅
in theintegration of the second term is the yield and absorbed dose rate coefficient, respectively, atthe energy E within a continuous energy spectra of beta emission.
(141) Interpolations of absorbed dose were carried out in a log-linear space. As thecoefficients for monoenergetic radiations obtained by Monte Carlo calculations addressed
only photons and electrons of 0.01 MeV and higher energy, the values at energies less than
0.01 MeV are set to zero.
(142) Radionuclide specific organ equivalent dose rate coefficients were evaluated for1252 radionuclides of 97 elements compiled in Publication 107 (ICRP, 2008) distributed insoil, air, and water, and are given in tabular form in the electronic supplement accompanying
this report. In the electronic supplement a summary information, on the nuclear
transformation of radionuclides can be also found (ICRP, 2008).

1861

7.2. Coefficients for effective dose rates

1862
1863
1864
1865
1866
1867

(143) As per definition of effective dose in Publication 103 (ICRP, 2007), the organ
equivalent doses of both male and female phantoms were used for its computation.
Radionuclide specific effective dose rate coefficients were derived from the radionuclide
specific organ equivalent dose rate coefficients discussed above. The effective dose rate
coefficient (𝑒𝑒̇ 𝑆𝑆,𝑁𝑁 ) for exposure mode (S) and radionuclide (N) was computed as follows:

1868
1869
1870
1871
1872

∞
𝑆𝑆 (𝐸𝐸 )̇ 𝑆𝑆ℎ̇𝑇𝑇𝑆𝑆,𝑁𝑁 = ∑𝑅𝑅 𝑤𝑤𝑅𝑅 �∑𝑖𝑖 𝑌𝑌𝑅𝑅,𝑖𝑖 (𝐸𝐸𝑖𝑖 ) ∙ 𝑑𝑑̇𝑇𝑇,𝑅𝑅
𝑖𝑖 + ∫0 𝑌𝑌𝑅𝑅 (𝐸𝐸) ∙ 𝑑𝑑 𝑇𝑇,𝑅𝑅 (𝐸𝐸)𝑑𝑑𝑑𝑑 �𝑆𝑆,𝑁𝑁,𝐹𝐹ℎ̇𝑆𝑆,𝑁𝑁,𝑀𝑀 +ℎ̇𝑇𝑇𝑒𝑒̇ 𝑆𝑆,𝑁𝑁 = ∑𝑇𝑇 𝑤𝑤𝑇𝑇 � 𝑇𝑇2

� (7.2)(7.1)

where 𝑤𝑤𝑇𝑇 represents the tissue weighting factor, ℎ̇𝑇𝑇𝑆𝑆,𝑁𝑁,𝑀𝑀 and ℎ̇ 𝑇𝑇𝑆𝑆,𝑁𝑁,𝐹𝐹 are the equivalent dose rate
coefficients to the tissue (T) of male and female, respectively, for radionuclide (N) in
exposure mode (S).

78

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1873
1874
1875

(144) The radionuclide specific effective dose rate coefficients are given in tabular form infolders ‘Soil contamination’, ‘Air submersion’ and ‘Water immersion’ of the electronic
supplement accompanying this report.

1876

7.3. Coefficients for air kerma and ambient dose equivalent rate

1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897

(145) Radionuclide specific coefficients of air kerma rate ( 𝑘𝑘̇𝑎𝑎𝑆𝑆,𝑁𝑁 ) and ambient dose
equivalent rate (ℎ̇∗ (10)𝑆𝑆,𝑁𝑁 ) were evaluated for photon sources in the soil contamination andair submersion geometries using the monoenergetic data and nuclear decay data as follows:𝑘𝑘̇𝑎𝑎𝑆𝑆,𝑁𝑁 = ∑𝑖𝑖 𝑌𝑌photon,𝑖𝑖 (𝐸𝐸𝑖𝑖 ) ∙ 𝑘𝑘̇𝑎𝑎𝑆𝑆 (𝐸𝐸𝑖𝑖 )(7.3)ℎ̇∗ (10)𝑆𝑆,𝑁𝑁 = ∑𝑖𝑖 𝑌𝑌photon,𝑖𝑖 (𝐸𝐸𝑖𝑖 ) ∙ ℎ̇∗ (10)𝑆𝑆 (𝐸𝐸𝑖𝑖 ) (7.4)

where 𝑌𝑌photon,𝑖𝑖 is the yield of i-th photon emitted from nuclear decay of a nuclide (N) withenergy (𝐸𝐸𝑖𝑖 ), and 𝑘𝑘̇𝑎𝑎𝑆𝑆 and ℎ̇∗ (10)𝑆𝑆 indicate the air kerma and ambient dose equivalent rate
coefficients, respectively, at the energy of 𝐸𝐸𝑖𝑖 .
(146) The values of 𝑘𝑘̇𝑎𝑎𝑆𝑆 (𝐸𝐸𝑖𝑖 ) and ℎ ̇∗ (10)𝑆𝑆 (𝐸𝐸𝑖𝑖 ) were determined from the data ofmonoenergetic photon sources by log-log interpolation.
(147) The radionuclide specific air kerma and ambient dose equivalent rate coefficientsfor soil contamination and air submersion are listed under folders ‘Soil contamination’ and‘Air submersion’ of the electronic supplement of this publication, together with the data forradionuclide specific effective dose rates. Similarly to the radionuclide-specific organ
equivalent dose rate coefficients, these air kerma and ambient dose equivalent rates forradionuclides were estimated by using the ICRP Publication 107 decay data (ICRP, 2008)
summerised in the electronic supplement of this publication.

79

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1898

8. APPLICATION OF DOSE RATE COEFFICIENTS

1899
1900

8.1. Application of dose rate coefficients to various depth profiles ofradionuclides in soil

1901

8.1.1. Planar sources in specific depths

1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915

(148) As described in Section 5.1, the dose rate coefficients for soil contamination were
evaluated for planar sources at five source depths expressed in mean free path (mfp) of thephotons in soil (i.e. 0.0, 0.2, 1.0, 2.5, and 4.0 mfp). The source depth can be expressed as
mass per unit area in units of g cm-2, which is independent of the soil density since absorption
is depending only on the mass thickness. The mean free path of photons depends on photon
energy. For instance, a specific source depth of 3.0 g cm-2 corresponds to 72.3, 0.54, and 0.14
mfp of 0.01, 0.1, and 2.0 MeV photons in the soil, respectively. Dose rate coefficients formonoenergetic photons emitted from a planar source at a specific depth (in g cm-2) can bereconstructed from the data at corresponding mean free path using a log-log interpolation.
Tables 8.1 to 8.3 tabulate the effective dose rate coefficients for planar sources at specificdepths of 0.5, 3.0, and 10.0 g cm-2 for monoenergetic photons. The depth of 0.5 g cm-2
approximates well the ground roughness, whereas 3.0 g cm-2 is the typical deposition depth
for radiocaesium and 10.0 g cm-2 is roughly the maximum depth where caesium has been
observed.

1916

8.1.2. Volumetric sources

1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933

(149) Measurements around the Fukushima area (Matsuda et al., 2015) revealed that thedepth profile of radionuclides in soil changes over time due to terrestrial ecosystems.
Calculating dose rate coefficients for each depth profile is not practical, therefore a method to
obtain dose rate coefficients for volumetric sources having arbitrary depth profiles is proposed.
Note that the depth profile of volumetric sources indicates the vertical distribution of theactivity concentration along the depth in the soil, whereas the horizontal distribution isassumed to be uniform.
(150) Dose rate coefficients for volumetric sources having any arbitrary depth profile canbe obtained using the data for planar sources in depths given in unit of g cm-2, and aweighted-integral method as described by Satoh et al (Satoh et al., 2015, 2017). The
weighted-integral method describes a depth profile in the soil with weights, 𝑤𝑤(𝜁𝜁), regarding aradioactivity concentration distributed along a depth, ζ, described in g cm-2 and it is applicable
to any depth profile e.g. exponential, Gaussian or uniform. Note that 𝑤𝑤(𝜁𝜁) expresses the depth
profile of the radioactivity concentration as a relative value to those activities at other depths
without providing the absolute values.
(151) The coefficients for a volumetric source, ℎv̇ , are derived as follows:

1934
1935
1936
1937

ℎ̇v =

1 𝜁𝜁2
� ℎ̇ (𝜁𝜁) ∙ 𝑤𝑤(𝜁𝜁) 𝑑𝑑𝑑𝑑
𝑊𝑊 𝜁𝜁1 p
𝜁𝜁2

𝑊𝑊 = � 𝑤𝑤(𝜁𝜁) 𝑑𝑑𝑑𝑑
𝜁𝜁1

80

(8.1)

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1938
1939
1940
1941
1942
1943
1944
1945

where ℎ̇p (𝜁𝜁) is the dose rate coefficient for a planar source located at a depth ζ, 𝜁𝜁1 and 𝜁𝜁2 are
the minimum and maximum depths of the volumetric source in the soil, respectively and 𝑊𝑊 isthe total weight in that depth profile.
(152) Matsuda et al. (2015) reported that the depth profiles of radioactive caesium in soil
observed in the Fukushima area after the accident in 2011 are fitted with an exponentialfunction using the equation of weight 𝑤𝑤(ζ) as follows:

1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961

where the factor 𝛼𝛼 indicates the weight at the surface of the ground, and the parameter β is therelaxation mass per unit area. The magnitude of β is an indication of the radionuclide
penetration in the soil with large values of β indicating a deeper penetration. The unit ofrelaxation mass per unit area is g cm-2.
(153) To examine the validity of the weighted-integral method, Satoh et al (2015)
incorporated an exponentially distributed volumetric source of 137Cs with β=1.0 into the
PHITS code and directly calculated the energy spectrum and the effective dose rate. It was
found that the reconstructed volumetric source was a good approximation of the source
directly calculated via Monte Carlo methods.
(154) Tables 8.4 to 8.7 list the effective dose rate coefficients evaluated for each age, formonoenergetic photon sources and volumetric sources distributed with exponential profiles
with β= 0.5, 1.0, 2.5, and 5.0 g cm-2, respectively. Nuclide-specific organ equivalent andeffective dose coefficients for these volumetric sources can be found in the electronic
supplement.

𝜁𝜁

𝑤𝑤(ζ) = α ∙ exp(− 𝛽𝛽)

(8.2)

81

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1962
1963
1964

Table 8.1. Effective dose rate, ambient dose equivalent rate and air kerma rate coefficients formonoenergetic photon sources distributed at a depth of 0.5 g cm-2 in the soil. Ambient dose
equivalent rate and air kerma rate coefficients were estimated at 1 m above ground.
EnergyEffective dose rate coefficient(MeV)(nSv h-1 Bq-1 m2)
Adult

15 yr

10 yr

5 yr

ℎ̇∗ (10)
1 yr(nGy h-1
Bq-1 m2)

Newborn

0.010

1.10E-12 1.01E-12 1.29E-12 1.51E-12 1.49E-12 2.04E-12 1.35E-12 1.64E-10

0.015

3.49E-08 3.77E-08 6.08E-08 5.99E-08 8.30E-08 1.22E-07 6.93E-07 2.52E-06

0.020

1.02E-06 1.19E-06 1.60E-06 1.86E-06 2.24E-06 3.23E-06 1.73E-05 2.82E-05

0.030

1.43E-05 1.62E-05 1.95E-05 2.51E-05 2.85E-05 3.98E-05 1.10E-04 1.01E-04

0.040

3.95E-05 4.44E-05 5.14E-05 6.36E-05 7.05E-05 8.61E-05 1.89E-04 1.34E-04

0.050

6.60E-05 7.36E-05 8.27E-05 9.90E-05 1.11E-04 1.28E-04 2.35E-04 1.46E-04

0.060

1.01E-04 1.10E-04 1.23E-04 1.42E-04 1.60E-04 1.80E-04 2.98E-04 1.76E-04

0.070

1.32E-04 1.43E-04 1.58E-04 1.79E-04 2.01E-04 2.23E-04 3.51E-04 2.04E-04

0.080

1.64E-04 1.77E-04 1.93E-04 2.16E-04 2.43E-04 2.67E-04 4.03E-04 2.36E-04

0.100

2.20E-04 2.36E-04 2.52E-04 2.80E-04 3.12E-04 3.45E-04 5.02E-04 3.00E-04

0.150

3.62E-04 3.81E-04 4.09E-04 4.56E-04 5.08E-04 5.61E-04 7.64E-04 4.96E-04

0.200

4.97E-04 5.27E-04 5.66E-04 6.32E-04 7.01E-04 7.82E-04 1.02E-03 6.94E-04

0.300

7.78E-04 8.21E-04 8.83E-04 9.84E-04 1.09E-03 1.22E-03 1.50E-03 1.10E-03

0.400

1.07E-03 1.12E-03 1.20E-03 1.34E-03 1.48E-03 1.67E-03 1.97E-03 1.50E-03

0.500

1.37E-03 1.41E-03 1.53E-03 1.68E-03 1.87E-03 2.11E-03 2.43E-03 1.90E-03

0.600

1.66E-03 1.71E-03 1.84E-03 2.02E-03 2.25E-03 2.54E-03 2.86E-03 2.29E-03

0.800

2.21E-03 2.29E-03 2.45E-03 2.67E-03 2.96E-03 3.34E-03 3.65E-03 2.99E-03

1.000

2.66E-03 2.76E-03 2.95E-03 3.20E-03 3.51E-03 3.95E-03 4.19E-03 3.52E-03

1.500

3.97E-03 4.07E-03 4.35E-03 4.69E-03 5.10E-03 5.69E-03 5.88E-03 5.06E-03

2.000

5.18E-03 5.31E-03 5.66E-03 6.08E-03 6.57E-03 7.30E-03 7.45E-03 6.50E-03

3.000

7.35E-03 7.57E-03 8.03E-03 8.60E-03 9.18E-03 1.01E-02 1.03E-02 9.08E-03

4.000

9.26E-03 9.59E-03 1.01E-02 1.08E-02 1.14E-02 1.26E-02 1.27E-02 1.14E-02

5.000

1.10E-02 1.14E-02 1.20E-02 1.28E-02 1.34E-02 1.47E-02 1.49E-02 1.34E-02

6.000

1.27E-02 1.32E-02 1.38E-02 1.47E-02 1.53E-02 1.66E-02 1.69E-02 1.53E-02

8.000

1.63E-02 1.66E-02 1.75E-02 1.86E-02 1.92E-02 2.07E-02 2.10E-02 1.94E-02

1965
1966

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1967
1968
1969

Table 8.2. Effective dose rate, ambient dose equivalent rate and air kerma rate coefficients formonoenergetic photon sources distributed at a depth of 3.0 g cm-2 in the soil. Ambient dose
equivalent rate and air kerma rate coefficients were estimated at 1 m above ground.
EnergyEffective dose rate coefficient(MeV)(nSv h-1 Bq-1 m2)
Adult

15 yr

10 yr

5 yr

ℎ̇∗ (10)
1 yr(nGy h-1
Bq-1 m2)

Newborn

0.010

0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

0.015

0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

0.020

2.37E-11 2.53E-11 3.42E-11 4.18E-11 4.20E-11 6.70E-11 5.48E-10 8.98E-10

0.030

2.31E-07 2.65E-07 3.00E-07 3.94E-07 4.61E-07 6.23E-07 2.29E-06 2.12E-06

0.040

3.81E-06 4.19E-06 4.69E-06 5.84E-06 6.66E-06 8.32E-06 2.11E-05 1.51E-05

0.050

1.31E-05 1.44E-05 1.59E-05 1.88E-05 2.14E-05 2.51E-05 5.26E-05 3.32E-05

0.060

2.70E-05 2.97E-05 3.28E-05 3.78E-05 4.09E-05 4.67E-05 9.04E-05 5.41E-05

0.070

4.32E-05 4.71E-05 5.17E-05 5.83E-05 6.29E-05 6.92E-05 1.28E-04 7.54E-05

0.080

6.14E-05 6.64E-05 7.22E-05 8.02E-05 8.69E-05 9.34E-05 1.68E-04 9.89E-05

0.100

9.44E-05 1.01E-04 1.07E-04 1.19E-04 1.27E-04 1.35E-04 2.35E-04 1.40E-04

0.150

1.72E-04 1.80E-04 1.92E-04 2.10E-04 2.24E-04 2.38E-04 3.90E-04 2.49E-04

0.200

2.39E-04 2.54E-04 2.71E-04 2.97E-04 3.14E-04 3.37E-04 5.30E-04 3.53E-04

0.300

3.71E-04 3.92E-04 4.20E-04 4.58E-04 4.82E-04 5.21E-04 7.78E-04 5.51E-04

0.400

5.01E-04 5.22E-04 5.57E-04 6.07E-04 6.36E-04 6.89E-04 9.93E-04 7.33E-04

0.500

6.27E-04 6.44E-04 6.85E-04 7.46E-04 7.81E-04 8.45E-04 1.18E-03 9.02E-04

0.600

7.49E-04 7.64E-04 8.10E-04 8.79E-04 9.20E-04 9.96E-04 1.36E-03 1.06E-03

0.800

9.73E-04 1.01E-03 1.07E-03 1.15E-03 1.21E-03 1.31E-03 1.73E-03 1.39E-03

1.000

1.18E-03 1.23E-03 1.29E-03 1.38E-03 1.45E-03 1.57E-03 1.99E-03 1.64E-03

1.500

1.97E-03 2.03E-03 2.14E-03 2.27E-03 2.40E-03 2.61E-03 3.09E-03 2.62E-03

2.000

2.77E-03 2.84E-03 3.00E-03 3.18E-03 3.37E-03 3.66E-03 4.17E-03 3.59E-03

3.000

4.30E-03 4.42E-03 4.64E-03 4.93E-03 5.19E-03 5.63E-03 6.19E-03 5.44E-03

4.000

5.70E-03 5.87E-03 6.14E-03 6.51E-03 6.81E-03 7.38E-03 7.98E-03 7.09E-03

5.000

6.99E-03 7.21E-03 7.52E-03 7.96E-03 8.26E-03 8.92E-03 9.59E-03 8.58E-03

6.000

8.23E-03 8.48E-03 8.82E-03 9.33E-03 9.62E-03 1.03E-02 1.11E-02 1.00E-02

8.000

1.09E-02 1.11E-02 1.15E-02 1.22E-02 1.25E-02 1.33E-02 1.41E-02 1.30E-02

1970
1971

83

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1972
1973
1974

Table 8.3 Effective dose rate, ambient dose equivalent rate and air kerma rate coefficients formonoenergetic photon sources distributed at a depth of 10.0 g cm-2 in the soil. Ambient dose
equivalent rate and air kerma rate coefficients were estimated at 1 m above ground.
EnergyEffective dose rate coefficient(MeV)(nSv h-1 Bq-1 m2)
Adult

15 yr

10 yr

5 yr

ℎ̇∗ (10)
1 yr(nGy h-1
Bq-1 m2)

Newborn

0.010

0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

0.015

0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

0.020

0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00 0.00E+00

0.030

1.36E-11 1.75E-11 1.80E-11 2.10E-11 2.48E-11 3.29E-11 1.94E-10 1.81E-10

0.040

2.48E-08 3.02E-08 3.14E-08 3.88E-08 4.90E-08 5.65E-08 1.74E-07 1.23E-07

0.050

5.19E-07 5.84E-07 6.45E-07 7.71E-07 8.77E-07 1.03E-06 2.47E-06 1.58E-06

0.060

2.43E-06 2.66E-06 2.91E-06 3.42E-06 3.73E-06 4.26E-06 9.18E-06 5.51E-06

0.070

5.59E-06 6.05E-06 6.59E-06 7.59E-06 8.12E-06 9.15E-06 1.84E-05 1.09E-05

0.080

1.06E-05 1.15E-05 1.24E-05 1.41E-05 1.50E-05 1.65E-05 3.18E-05 1.88E-05

0.100

2.22E-05 2.38E-05 2.55E-05 2.86E-05 3.04E-05 3.26E-05 6.10E-05 3.62E-05

0.150

5.31E-05 5.65E-05 6.00E-05 6.61E-05 7.06E-05 7.45E-05 1.32E-04 8.30E-05

0.200

8.35E-05 8.85E-05 9.40E-05 1.03E-04 1.09E-04 1.16E-04 2.00E-04 1.30E-04

0.300

1.44E-04 1.51E-04 1.61E-04 1.76E-04 1.84E-04 1.96E-04 3.26E-04 2.23E-04

0.400

2.03E-04 2.12E-04 2.26E-04 2.46E-04 2.56E-04 2.75E-04 4.40E-04 3.14E-04

0.500

2.65E-04 2.75E-04 2.93E-04 3.18E-04 3.31E-04 3.57E-04 5.50E-04 4.06E-04

0.600

3.26E-04 3.37E-04 3.59E-04 3.89E-04 4.05E-04 4.38E-04 6.51E-04 4.95E-04

0.800

4.47E-04 4.65E-04 4.93E-04 5.30E-04 5.56E-04 6.01E-04 8.49E-04 6.66E-04

1.000

5.70E-04 5.92E-04 6.24E-04 6.70E-04 7.02E-04 7.56E-04 1.03E-03 8.25E-04

1.500

9.20E-04 9.50E-04 9.97E-04 1.06E-03 1.11E-03 1.20E-03 1.53E-03 1.28E-03

2.000

1.27E-03 1.30E-03 1.36E-03 1.45E-03 1.51E-03 1.62E-03 2.01E-03 1.71E-03

3.000

1.90E-03 1.95E-03 2.03E-03 2.14E-03 2.23E-03 2.38E-03 2.87E-03 2.49E-03

4.000

2.44E-03 2.51E-03 2.59E-03 2.73E-03 2.82E-03 2.99E-03 3.56E-03 3.13E-03

5.000

2.91E-03 2.98E-03 3.07E-03 3.22E-03 3.30E-03 3.49E-03 4.12E-03 3.65E-03

6.000

3.34E-03 3.42E-03 3.50E-03 3.67E-03 3.74E-03 3.93E-03 4.62E-03 4.12E-03

8.000

4.29E-03 4.39E-03 4.45E-03 4.67E-03 4.68E-03 4.91E-03 5.70E-03 5.17E-03

1975
1976
1977

84

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1978
1979
1980
1981

Table 8.4. Effective dose rate, ambient dose equivalent rate and air kerma rate coefficients formonoenergetic photon sources distributed exponentially from the ground surface to 100.0 g
cm-2 with β=0.5 g cm-2 in the soil. Ambient dose equivalent rate and air kerma rate
coefficients were estimated at 1 m above ground.
EnergyEffective dose rate coefficient(MeV)(nSv h-1 Bq-1 m2)
Adult

15 yr

10 yr

5 yr

ℎ̇∗ (10)
1 yr(nGy h-1
Bq-1 m2)

Newborn

0.010

1.00E-06 9.67E-07 1.32E-06 1.68E-06 3.18E-06 6.06E-06 9.88E-07 1.20E-04

0.015

3.37E-06 3.78E-06 5.97E-06 7.37E-06 1.09E-05 2.13E-05 5.06E-05 1.93E-04

0.020

9.01E-06 1.06E-05 1.43E-05 1.98E-05 2.50E-05 4.36E-05 1.33E-04 2.16E-04

0.030

3.26E-05 3.73E-05 4.51E-05 6.25E-05 7.65E-05 1.12E-04 2.31E-04 2.11E-04

0.040

6.24E-05 7.07E-05 8.19E-05 1.06E-04 1.25E-04 1.61E-04 2.84E-04 1.99E-04

0.050

9.06E-05 1.02E-04 1.17E-04 1.41E-04 1.67E-04 1.99E-04 3.15E-04 1.94E-04

0.060

1.23E-04 1.35E-04 1.51E-04 1.76E-04 2.05E-04 2.37E-04 3.58E-04 2.11E-04

0.070

1.53E-04 1.66E-04 1.83E-04 2.10E-04 2.41E-04 2.72E-04 3.98E-04 2.32E-04

0.080

1.82E-04 1.97E-04 2.16E-04 2.44E-04 2.78E-04 3.09E-04 4.42E-04 2.59E-04

0.100

2.39E-04 2.56E-04 2.74E-04 3.06E-04 3.46E-04 3.86E-04 5.38E-04 3.22E-04

0.150

3.84E-04 4.04E-04 4.35E-04 4.86E-04 5.46E-04 6.07E-04 8.03E-04 5.22E-04

0.200

5.23E-04 5.55E-04 5.95E-04 6.68E-04 7.45E-04 8.36E-04 1.06E-03 7.26E-04

0.300

8.13E-04 8.57E-04 9.22E-04 1.03E-03 1.15E-03 1.30E-03 1.56E-03 1.14E-03

0.400

1.11E-03 1.16E-03 1.25E-03 1.39E-03 1.55E-03 1.76E-03 2.04E-03 1.55E-03

0.500

1.42E-03 1.47E-03 1.59E-03 1.75E-03 1.95E-03 2.21E-03 2.51E-03 1.96E-03

0.600

1.72E-03 1.77E-03 1.91E-03 2.10E-03 2.34E-03 2.65E-03 2.95E-03 2.36E-03

0.800

2.28E-03 2.36E-03 2.52E-03 2.76E-03 3.06E-03 3.47E-03 3.75E-03 3.08E-03

1.000

2.73E-03 2.84E-03 3.04E-03 3.29E-03 3.63E-03 4.08E-03 4.30E-03 3.61E-03

1.500

4.06E-03 4.16E-03 4.45E-03 4.80E-03 5.23E-03 5.84E-03 6.00E-03 5.16E-03

2.000

5.28E-03 5.41E-03 5.78E-03 6.21E-03 6.71E-03 7.46E-03 7.58E-03 6.61E-03

3.000

7.46E-03 7.69E-03 8.17E-03 8.74E-03 9.33E-03 1.03E-02 1.04E-02 9.22E-03

4.000

9.39E-03 9.72E-03 1.03E-02 1.10E-02 1.16E-02 1.28E-02 1.29E-02 1.15E-02

5.000

1.12E-02 1.16E-02 1.22E-02 1.30E-02 1.36E-02 1.49E-02 1.51E-02 1.36E-02

6.000

1.28E-02 1.33E-02 1.40E-02 1.49E-02 1.55E-02 1.69E-02 1.71E-02 1.55E-02

8.000

1.64E-02 1.68E-02 1.77E-02 1.89E-02 1.94E-02 2.09E-02 2.12E-02 1.96E-02

1982
1983

85

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1984
1985
1986
1987

Table 8.5. Effective dose rate, ambient dose equivalent rate and air kerma rate coefficients formonoenergetic photon sources distributed exponentially from the ground surface to 100.0 g
cm-2 with β=1.0 g cm-2 in the soil. Ambient dose equivalent rate and air kerma rate
coefficients were estimated at 1 m above ground.
EnergyEffective dose rate coefficient(MeV)(nSv h-1 Bq-1 m2)
Adult

15 yr

10 yr

5 yr

ℎ̇∗ (10)
1 yr(nGy h-1
Bq-1 m2)

Newborn

0.010

5.27E-07 5.10E-07 6.96E-07 8.86E-07 1.67E-06 3.19E-06 5.21E-07 6.33E-05

0.015

1.83E-06 2.05E-06 3.25E-06 3.99E-06 5.91E-06 1.15E-05 2.76E-05 1.05E-04

0.020

5.13E-06 6.06E-06 8.12E-06 1.12E-05 1.41E-05 2.45E-05 7.61E-05 1.24E-04

0.030

2.07E-05 2.36E-05 2.85E-05 3.92E-05 4.77E-05 6.95E-05 1.49E-04 1.36E-04

0.040

4.37E-05 4.94E-05 5.71E-05 7.31E-05 8.59E-05 1.10E-04 2.02E-04 1.42E-04

0.050

6.81E-05 7.64E-05 8.70E-05 1.05E-04 1.23E-04 1.45E-04 2.40E-04 1.48E-04

0.060

9.66E-05 1.06E-04 1.18E-04 1.38E-04 1.58E-04 1.81E-04 2.86E-04 1.68E-04

0.070

1.23E-04 1.34E-04 1.48E-04 1.68E-04 1.91E-04 2.13E-04 3.27E-04 1.90E-04

0.080

1.50E-04 1.62E-04 1.77E-04 1.99E-04 2.24E-04 2.47E-04 3.70E-04 2.17E-04

0.100

2.01E-04 2.14E-04 2.29E-04 2.55E-04 2.85E-04 3.15E-04 4.59E-04 2.74E-04

0.150

3.30E-04 3.47E-04 3.72E-04 4.15E-04 4.60E-04 5.08E-04 6.99E-04 4.53E-04

0.200

4.51E-04 4.79E-04 5.13E-04 5.73E-04 6.33E-04 7.05E-04 9.28E-04 6.33E-04

0.300

7.03E-04 7.41E-04 7.97E-04 8.87E-04 9.78E-04 1.10E-03 1.37E-03 9.94E-04

0.400

9.64E-04 1.00E-03 1.08E-03 1.20E-03 1.32E-03 1.49E-03 1.79E-03 1.35E-03

0.500

1.23E-03 1.27E-03 1.37E-03 1.51E-03 1.67E-03 1.88E-03 2.20E-03 1.71E-03

0.600

1.50E-03 1.54E-03 1.66E-03 1.82E-03 2.01E-03 2.26E-03 2.59E-03 2.07E-03

0.800

1.99E-03 2.06E-03 2.21E-03 2.41E-03 2.65E-03 2.99E-03 3.31E-03 2.71E-03

1.000

2.40E-03 2.50E-03 2.67E-03 2.89E-03 3.16E-03 3.55E-03 3.82E-03 3.20E-03

1.500

3.63E-03 3.72E-03 3.97E-03 4.27E-03 4.63E-03 5.16E-03 5.40E-03 4.63E-03

2.000

4.76E-03 4.88E-03 5.20E-03 5.57E-03 6.01E-03 6.67E-03 6.87E-03 5.99E-03

3.000

6.81E-03 7.01E-03 7.43E-03 7.95E-03 8.47E-03 9.34E-03 9.54E-03 8.44E-03

4.000

8.63E-03 8.93E-03 9.42E-03 1.00E-02 1.06E-02 1.16E-02 1.19E-02 1.06E-02

5.000

1.03E-02 1.07E-02 1.12E-02 1.20E-02 1.25E-02 1.37E-02 1.39E-02 1.25E-02

6.000

1.19E-02 1.23E-02 1.29E-02 1.38E-02 1.43E-02 1.55E-02 1.59E-02 1.44E-02

8.000

1.53E-02 1.56E-02 1.65E-02 1.75E-02 1.80E-02 1.94E-02 1.98E-02 1.82E-02

1988
1989

86

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1990
1991
1992
1993

Table 8.6. Effective dose rate, ambient dose equivalent rate and air kerma rate coefficients formonoenergetic photon sources distributed exponentially from the ground surface to 100.0 g
cm-2 with β=2.5 g cm-2 in the soil. Ambient dose equivalent rate and air kerma rate
coefficients were estimated at 1 m above ground.
EnergyEffective dose rate coefficient(MeV)(nSv h-1 Bq-1 m2)
Adult

15 yr

10 yr

5 yr

ℎ̇∗ (10)
1 yr(nGy h-1
Bq-1 m2)

Newborn

0.010

2.18E-07 2.11E-07 2.88E-07 3.66E-07 6.91E-07 1.32E-06 2.15E-07 2.62E-05

0.015

7.73E-07 8.66E-07 1.37E-06 1.68E-06 2.49E-06 4.84E-06 1.17E-05 4.44E-05

0.020

2.24E-06 2.64E-06 3.54E-06 4.88E-06 6.13E-06 1.06E-05 3.34E-05 5.43E-05

0.030

9.96E-06 1.14E-05 1.37E-05 1.87E-05 2.27E-05 3.28E-05 7.26E-05 6.66E-05

0.040

2.37E-05 2.67E-05 3.08E-05 3.92E-05 4.57E-05 5.79E-05 1.12E-04 7.86E-05

0.050

4.08E-05 4.56E-05 5.16E-05 6.21E-05 7.19E-05 8.48E-05 1.47E-04 9.09E-05

0.060

6.17E-05 6.77E-05 7.53E-05 8.75E-05 9.90E-05 1.13E-04 1.87E-04 1.10E-04

0.070

8.22E-05 8.92E-05 9.82E-05 1.11E-04 1.25E-04 1.39E-04 2.23E-04 1.30E-04

0.080

1.03E-04 1.12E-04 1.22E-04 1.36E-04 1.52E-04 1.66E-04 2.62E-04 1.54E-04

0.100

1.44E-04 1.54E-04 1.64E-04 1.82E-04 2.01E-04 2.19E-04 3.38E-04 2.02E-04

0.150

2.45E-04 2.58E-04 2.76E-04 3.06E-04 3.35E-04 3.66E-04 5.32E-04 3.43E-04

0.200

3.39E-04 3.59E-04 3.85E-04 4.27E-04 4.66E-04 5.12E-04 7.14E-04 4.83E-04

0.300

5.30E-04 5.59E-04 6.00E-04 6.64E-04 7.23E-04 8.01E-04 1.06E-03 7.61E-04

0.400

7.27E-04 7.58E-04 8.14E-04 8.97E-04 9.76E-04 1.09E-03 1.38E-03 1.04E-03

0.500

9.30E-04 9.60E-04 1.03E-03 1.13E-03 1.23E-03 1.37E-03 1.69E-03 1.31E-03

0.600

1.13E-03 1.16E-03 1.25E-03 1.36E-03 1.49E-03 1.66E-03 1.99E-03 1.58E-03

0.800

1.51E-03 1.57E-03 1.67E-03 1.81E-03 1.98E-03 2.21E-03 2.56E-03 2.08E-03

1.000

1.84E-03 1.91E-03 2.03E-03 2.19E-03 2.37E-03 2.64E-03 2.97E-03 2.47E-03

1.500

2.82E-03 2.89E-03 3.07E-03 3.30E-03 3.55E-03 3.93E-03 4.26E-03 3.64E-03

2.000

3.74E-03 3.84E-03 4.07E-03 4.36E-03 4.67E-03 5.15E-03 5.48E-03 4.76E-03

3.000

5.45E-03 5.61E-03 5.93E-03 6.32E-03 6.71E-03 7.36E-03 7.71E-03 6.80E-03

4.000

7.00E-03 7.23E-03 7.60E-03 8.09E-03 8.51E-03 9.30E-03 9.69E-03 8.63E-03

5.000

8.42E-03 8.71E-03 9.13E-03 9.70E-03 1.01E-02 1.10E-02 1.15E-02 1.03E-02

6.000

9.78E-03 1.01E-02 1.06E-02 1.12E-02 1.16E-02 1.26E-02 1.31E-02 1.19E-02

8.000

1.27E-02 1.30E-02 1.36E-02 1.44E-02 1.48E-02 1.59E-02 1.65E-02 1.52E-02

1994
1995

87

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

1996
1997
1998
1999

Table 8.7. Effective dose rate, ambient dose equivalent rate and air kerma rate coefficients formonoenergetic photon sources distributed exponentially from the ground surface to 100.0 g
cm-2 with β=5.0 g cm-2 in the soil. Ambient dose equivalent rate and air kerma rate
coefficients were estimated at 1 m above ground.
EnergyEffective dose rate coefficient(MeV)(nSv h-1 Bq-1 m2)
Adult

15 yr

10 yr

5 yr

ℎ̇∗ (10)
1 yr(nGy h-1
Bq-1 m2)

Newborn

0.010

1.10E-07 1.06E-07 1.45E-07 1.85E-07 3.49E-07 6.66E-07 1.09E-07 1.32E-05

0.015

3.94E-07 4.41E-07 6.97E-07 8.56E-07 1.27E-06 2.46E-06 5.95E-06 2.26E-05

0.020

1.16E-06 1.36E-06 1.83E-06 2.51E-06 3.16E-06 5.44E-06 1.72E-05 2.81E-05

0.030

5.36E-06 6.12E-06 7.37E-06 1.01E-05 1.21E-05 1.76E-05 3.94E-05 3.61E-05

0.040

1.36E-05 1.53E-05 1.76E-05 2.24E-05 2.60E-05 3.29E-05 6.49E-05 4.57E-05

0.050

2.49E-05 2.78E-05 3.14E-05 3.77E-05 4.35E-05 5.12E-05 9.09E-05 5.64E-05

0.060

3.95E-05 4.33E-05 4.82E-05 5.59E-05 6.28E-05 7.14E-05 1.22E-04 7.20E-05

0.070

5.44E-05 5.91E-05 6.50E-05 7.36E-05 8.20E-05 9.08E-05 1.51E-04 8.81E-05

0.080

7.04E-05 7.61E-05 8.29E-05 9.25E-05 1.03E-04 1.12E-04 1.82E-04 1.07E-04

0.100

1.02E-04 1.08E-04 1.16E-04 1.29E-04 1.41E-04 1.53E-04 2.43E-04 1.45E-04

0.150

1.79E-04 1.89E-04 2.02E-04 2.23E-04 2.43E-04 2.63E-04 3.96E-04 2.54E-04

0.200

2.51E-04 2.66E-04 2.85E-04 3.15E-04 3.41E-04 3.72E-04 5.40E-04 3.63E-04

0.300

3.97E-04 4.19E-04 4.49E-04 4.95E-04 5.34E-04 5.87E-04 8.08E-04 5.77E-04

0.400

5.46E-04 5.69E-04 6.10E-04 6.71E-04 7.23E-04 7.98E-04 1.06E-03 7.87E-04

0.500

6.99E-04 7.21E-04 7.73E-04 8.46E-04 9.12E-04 1.01E-03 1.30E-03 9.96E-04

0.600

8.50E-04 8.72E-04 9.34E-04 1.02E-03 1.10E-03 1.22E-03 1.52E-03 1.20E-03

0.800

1.14E-03 1.18E-03 1.26E-03 1.36E-03 1.47E-03 1.63E-03 1.96E-03 1.59E-03

1.000

1.39E-03 1.44E-03 1.53E-03 1.65E-03 1.77E-03 1.96E-03 2.28E-03 1.89E-03

1.500

2.15E-03 2.21E-03 2.34E-03 2.51E-03 2.69E-03 2.95E-03 3.30E-03 2.81E-03

2.000

2.87E-03 2.95E-03 3.12E-03 3.34E-03 3.56E-03 3.90E-03 4.27E-03 3.70E-03

3.000

4.24E-03 4.36E-03 4.59E-03 4.88E-03 5.17E-03 5.64E-03 6.06E-03 5.33E-03

4.000

5.48E-03 5.65E-03 5.93E-03 6.29E-03 6.60E-03 7.18E-03 7.65E-03 6.80E-03

5.000

6.62E-03 6.83E-03 7.14E-03 7.57E-03 7.88E-03 8.52E-03 9.06E-03 8.12E-03

6.000

7.70E-03 7.95E-03 8.29E-03 8.77E-03 9.06E-03 9.77E-03 1.04E-02 9.36E-03

8.000

1.01E-02 1.03E-02 1.07E-02 1.14E-02 1.16E-02 1.24E-02 1.31E-02 1.20E-02

2000
2001

88

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2002

8.2. Radionuclide decay chain

2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022

(155) In this publication, external dose rate coefficients are evaluated for 1252
radionuclides of 97 elements compiled in Publication 107 (ICRP, 2008). Table XX (seeelectronic supplement of this publication) summarises nuclear decay characteristics of eachradionuclide. The nuclide-specific dose rate coefficients appearing on the electronic
supplement are based on the radiations emitted by the indicated radionuclide and do notinclude consideration of the radiations emitted by radioactive decay products. For eachradionuclide, the radioactive decay products, if formed, are identified in Table 1 of theElectronic Supplement.
(156) Dose rate coefficients for a radionuclide and its decay products should be combined
after consideration of the equations describing production and decay of daughter
radionuclides over time, and differences in environmental behaviour of the parent anddaughter nuclides. Such consideration is required for evaluation of the effective dose rate at a
specified time and the effective dose integrated over a specified period.
(157) The serial transformation by radioactive decay of each member of a radioactive
series is described by the Bateman equations (Bateman, 1910; ICRP, 1959; Skrable et al.,1974) and the following equations developed by Eckerman and Ryman (1993). Assume thatat time zero, the concentration of the parent nuclide on the surface of the ground is 𝐴𝐴10 (Bq m2) and that the effective dose, 𝐸𝐸 for an exposure period of one year is to be estimated. The
contribution to effective dose from nuclear transformation of the parent nuclide is given by

2023

(8.3)

2024
2025
2026
2027
2028
2029
2030

𝑔𝑔𝑔𝑔

where 𝑒𝑒̇𝐸𝐸,1 denotes the effective dose rate coefficient from ground surface exposure fornuclide 1 (Sv s-1 Bq-1 m2), 𝜆𝜆1 is the decay constant, in inverse seconds, for nuclide 1 (𝜆𝜆 =0.6931 …/𝑇𝑇1/2 ), and 𝑇𝑇 is the exposure period of one year or 3.15 × 107 s.
(158) Using the Bateman equations, the activity at time 𝑡𝑡 of chain members 𝑖𝑖, 𝑖𝑖 = 1, 2, ...,
can be expressed as

2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041

0
𝑔𝑔𝑔𝑔 𝐴𝐴1
𝐸𝐸 = 𝑒𝑒̇𝐸𝐸,1 �1 − 𝑒𝑒 −𝜆𝜆1 𝑇𝑇 � ,
𝜆𝜆1

where

𝑖𝑖
𝑖𝑖−1
𝑒𝑒 −𝜆𝜆𝑗𝑗 𝑡𝑡
0𝐴𝐴𝑖𝑖 (𝑡𝑡) = 𝐴𝐴1 � 𝑓𝑓𝑗𝑗,𝑗𝑗+1 𝜆𝜆𝑗𝑗 � 𝑖𝑖
∏ (𝜆𝜆 − 𝜆𝜆𝑗𝑗 )𝑗𝑗=1 𝑘𝑘=1 𝑘𝑘
𝑗𝑗=1
𝑘𝑘≠𝑗𝑗
𝑛𝑛

𝑎𝑎 × 𝑎𝑎2 ⋯ 𝑎𝑎𝑛𝑛 ,if 𝑛𝑛 ≥ 1
� 𝑎𝑎𝑖𝑖 = � 1
1,
if 𝑛𝑛 = 0
𝑖𝑖=1

,

,

(8.4)

and 𝑓𝑓𝑗𝑗,𝑗𝑗+1 denotes the fraction of the nuclear transformations of chain member (j) forming
member (j+1).
(159) The effective dose associated with an exposure period of duration (T), following acontamination event at t = 0 that results in a ground surface concentration of 𝐴𝐴10 , is89

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2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054

𝑔𝑔𝑔𝑔

𝑖𝑖
𝑛𝑛
𝑖𝑖−1
𝑒𝑒 −𝜆𝜆𝑗𝑗𝑇𝑇
𝑔𝑔𝑔𝑔
0
𝐸𝐸 = 𝐴𝐴1 � 𝑒𝑒̇𝐸𝐸,𝑖𝑖 � 𝑓𝑓𝑗𝑗,𝑗𝑗+1 𝜆𝜆𝑗𝑗 � 𝑖𝑖
∏ (𝜆𝜆 − 𝜆𝜆𝑗𝑗 )𝑗𝑗=1 𝑘𝑘=1 𝑘𝑘
𝑖𝑖=1
𝑗𝑗=1
𝑘𝑘≠𝑗𝑗

,

(8.5)

where 𝑒𝑒̇𝐸𝐸,𝑖𝑖 denotes the effective dose rate coefficient for ground surface exposure to nuclide(i), and all other factors are as defined above. If the parent radionuclide is long-lived relative
to the decay products, then at times T such that 𝜆𝜆𝑖𝑖 𝑇𝑇 > 5, i = 2 to n, 𝐸𝐸 can be estimated as
𝐸𝐸 = 𝐴𝐴10

𝑛𝑛

𝑖𝑖−1

𝑖𝑖=1

𝑗𝑗=1

1 − 𝑒𝑒 −𝜆𝜆1 𝑇𝑇
𝑔𝑔𝑔𝑔
� 𝑒𝑒̇𝐸𝐸,𝑖𝑖 � 𝑓𝑓𝑗𝑗,𝑗𝑗+1
𝜆𝜆1

,

(8.6)

(160) Under these conditions the activity of the decay products is in secular equilibriumwith the parent's activity. For example, application of Eq. (8.6) to 137Cs and its 137mBa decay
product would yield
𝐸𝐸 = 𝐴𝐴0Cs−137

1 − 𝑒𝑒 −𝜆𝜆Cs−137 𝑡𝑡 𝑔𝑔𝑔𝑔
𝑔𝑔𝑔𝑔
�𝑒𝑒̇𝐸𝐸,Cs−137 + 0.944 𝑒𝑒̇𝐸𝐸,Ba−137m �
𝜆𝜆Cs−137

,

(8.7)

2055
2056
2057
2058
2059
2060
2061

where 0.944 is the fraction of the 137Cs nuclear transformations forming 137mBa. If the decay
products are not short-lived relative to the parent, then it is necessary to evaluate Eq. (8.5).
(161) In many instances, the mathematical models describing the fate of radionuclides inthe environment (e.g. their dispersion of following release to the atmosphere) include anevaluation of the ingrowth of each radioactive decay product. The information of Table 1(Electronic Supplement) should be useful to those implementing such models.

2062
2063

8.3. Relationship between radioactivity in soil, effective dose, ambient dose
equivalent and personal dose equivalent

2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080

(162) Operational quantities were originally developed for the protection ofoccupationally exposed workers. The use of the operational quantities has been extended tomonitoring of radiation exposure of the public from natural and artificial environmental
sources of radiation. One of the applications is radiation monitoring in contaminatedenvironment by radionuclides released from nuclear facilities by an accident.
(163) After the Fukushima Daiichi Nuclear Power Plant accident in 2011, a large-scalenational environmental monitoring program was carried out, and comprehensive data
including radioactivity in soil and ambient dose equivalent rate, ℎ∗̇ (10) , were collected(NRA, 2012). In addition, many municipalities in Fukushima prefecture started individual
external dose monitoring for residents living in contaminated areas. The individual
monitoring of external exposure is performed using a personal dosimeter worn on the body.
(164) The personal dosimeters indicate personal dose equivalent, 𝐻𝐻p (10) . The
relationship between effective dose, 𝐸𝐸 , ambient dose equivalent, 𝐻𝐻 ∗ (10) and 𝐻𝐻p (10) has
been studied for workers in Publication 74 (ICRP, 1996b) and Publication 116 (ICRP, 2010)
for idealised exposure conditions. In routine calibrations, personal dosimeters on a phantom
are exposed in the reference direction, i.e. at 0°. The condition simulates antero-posterior(AP) geometry where workers face to radiation sources and are exposed to radiations from90

DRAFT REPORT FOR CONSULTATION: DO NOT REFERENCE

2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095

front to back. In the AP geometry, 𝐻𝐻p (10) provides a conservative estimate regarding 𝐸𝐸 forphoton energies up to 10 MeV. However, the radiation fields originated by large-scale
environmental contamination are multidirectional photon fields and their characteristics aredifferent from those in the AP geometry. Determining whether 𝐸𝐸 can be properly assessedusing the personal dosimeters, which have been calibrated for the reference direction, in theradiation field of the contaminated environment is a matter of great concern to ensure proper
protection of the public.
(165) Satoh et al. (2017) investigated the relation of 𝐸𝐸, 𝐻𝐻 ∗ (10) and 𝐻𝐻p (10) in radiation
fields originated from 134Cs and 137Cs in soil. In this study, 𝐸𝐸 and 𝐻𝐻p (10) monitored by apersonal dosemeter worn on the body, have been calculated using the paediatric (newborns; 1year-old, 5-year-old, 10-year-old, and 15-year-old children) and adult phantoms by radiationtransport techniques for planar sources of 134Cs and 137Cs distributed uniformly in various
depths in soil. The study indicates the quantity 𝐻𝐻p (10) provides a good estimate for 𝐸𝐸 in acontaminated environment and does not exceed 𝐻𝐻 ∗ (10) values at a height of 1 m above theground.

2096
2097

8.4. Comparison with new operational quantities for external radiation
proposed by ICRU

2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125

(166) The operational quantities for external exposure in use at the time of compilation ofthis report, were defined in the 1980s and have been implemented into legal metrology
worldwide since. Nevertheless, the existing system has some limitations (Bartlett and Dietze,
2010; Endo, 2016), ICRU xx (in preparation) and informs on further improvements toconsider changes in the fields of application, including the extension of radiation type andenergy range (ICRP, 2007, 2010, 2016a; ICRU, 2010). Ideally, the determination of an
operational quantity should give a value that is a close estimate of the value of the protection
quantity.
(167) The ICRU Report Committee 26 [ICRU Report xx (in preparation)] has examined
the rationale for the operational quantities, considering updated definitions of protection
quantities by ICRP (ICRP, 2007, 2010). They subsequently investigated a set of alternative
definitions for operational quantities. ICRU recommends a redefinition of the operational
quantities using coefficients that are based on protection quantities (Endo, 2016). Thus,
consideration was given to define new quantities by the value of particle fluence (aradiometric quantity) at the point of interest, multiplied by values of the conversion
coefficients to the protection quantities. This approach is justified because the reference
values of the conversion coefficients for the protection quantities are available (ICRP, 2010).
This change would avoid the use of different phantoms (anthropomorphic phantoms vs. ICRU
sphere or slab) and different forms of dose weighting for radiation quality (radiation
weighting factor vs quality factor) between the protection quantities and the operational
quantities.
(168) In the proposed definitions, the ambient dose 𝐻𝐻 ∗ , at a point in a radiation field, isdefined as the product of the particle energy fluence, 𝛷𝛷 , at that point and a conversion
coefficient, ℎ, relating the particle energy fluence to the maximum value of the effective dose,
𝐸𝐸max . The conversion coefficients are calculated for exposures of the whole-body of the ICRP
adult reference phantoms (ICRP, 2009a) for broad idealised parallel beams of the radiation
field incident in irradiation geometries along the antero-posterior (AP), postero-anterior (PA),left lateral (LLAT), right lateral (RLAT) axes, for 360° rotational (ROT) directions, fully

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2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137

isotropic irradiation (ISO), superior hemisphere semi-isotropic irradiation (SS-ISO), andinferior hemisphere semi-isotropic irradiation (IS-ISO) fields.
(169) The ambient dose coefficients are given by ℎ𝐸𝐸max,𝑖𝑖 (𝜀𝜀) = 𝐸𝐸max,𝑖𝑖 (𝜀𝜀)/𝛷𝛷(𝜀𝜀), where thefluence values are those for the particle type, 𝑖𝑖, at the point of interest, at each energy, 𝜀𝜀. For
particles of type 𝑖𝑖:
𝐻𝐻𝑖𝑖∗ = � ℎ𝐸𝐸max,𝑖𝑖 (𝜀𝜀)d𝛷𝛷𝑖𝑖 (𝜀𝜀)d𝜀𝜀d𝜀𝜀where d𝛷𝛷𝑖𝑖 (𝜀𝜀)/d𝜀𝜀 is the fluence of particles at that point with kinetic energies in the intervald𝜀𝜀 around 𝜀𝜀. The sum over all contributing particle types, 𝑖𝑖, is the quantity 𝐻𝐻 ∗ :𝐻𝐻 ∗ = � 𝐻𝐻𝑖𝑖∗

2138
2139
2140

The unit of ambient dose is J kg-1. The special name for the unit of ambient dose is sievert
(Sv).

2141

8.5. Application of dose rate coefficients for remediation planning

2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159

(170) The present publication provides radionuclide-specific dose rate coefficients formembers of the public resulting from environmental external exposures. These dose rate
coefficients could be utilised for planning of remediation from radioactive contamination of
the environment. Remediation activities, including decontamination, reduce exposure of the
public living in a contaminated area. A software has been developed to support decisionmaking and planning of remediation activities by optimisation of counter measures(Ulanovsky et al., 2011). The software addresses the annual effective dose of the population,and the dose rate coefficients given in this Publication are useful for this purpose.
(171) Estimation of dose reduction by decontamination for a specific situation requires
among other factors, consideration of source size, inhomogeneity of source distribution, anddecontamination factor. For that purpose, Satoh et al (2014) have developed a methodology
and software to estimate the effects of decontamination and the dose reduction effect resulting
from a decontamination scenario. To estimate the dose reduction for a specific contaminatedsite after decontamination measures, it is necessary to consider the inhomogeneity of thesource distribution as well as the size of the source. This estimation requires a different
approach than the one describes in this report and it is proposed by Satoh et al (2014).
(172) It is beyond the Task Group’s scope to address decontamination.

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2160

9. CONCLUSIONS

2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207

(173) This report provides age-dependent data sets of nuclide-specific reference effective
and organ equivalent dose rate coefficients to be used for the assessment of external dosefrom environmental exposure to the public for selected idealized environmental conditions
which are considered to be typical. These are exposure to contamination on or below theground surface and at different depths (soil contamination); submersion in a contaminatedatmospheric cloud (air submersion); and immersion in contaminated water (water immersion).
In the first two scenarios, air-over-ground geometry and a human body standing up-rightabove the ground were assumed.
(174) ICRP establishes for the first time reference dose rate coefficients for exposure toenvironmental radionuclides. These were computed for the ICRP voxel-based adult male andfemale reference computational phantoms (ICRP, 2009a) as well as for the 10 ICRP reference
paediatric phantoms representing the newborn, 1-year-old, 5-year-old, 10-year-old and 15year-old reference male and female reference individuals (ICRP 2018, in preparation).
Radiations considered include primary photons and electrons from environmentally dispersedradionuclides, scattered photons and electrons emitted within the environment, andbremsstrahlung photons produced via electron deceleration. The emitted electrons include
those of beta decay (negatrons and positrons) and ejected orbital electrons due to internalconversion and Auger processes in the electron shell of the newly formed atom.
(175) Organ equivalent dose rates increase with decreasing age because of the reduced
shielding effect of the smaller body and the closer vicinity of the source for groundcontamination. It was found that the effective dose varies relatively largely between the
newborn and a 1-year-old child. Effective dose rates for the reference 15-year adolescents areclose to those computed for the reference adults.
(176) The ambient dose equivalent rates and air kerma rates have been computed and are
given for both soil contamination and air submersion for the environmental geometries
considered. These data enable interpretation of monitoring data relating effective doses rates
to ambient dose equivalent rates or to air kerma rates. Ambient dose equivalent and air kerma
rates were found to provide conservative estimates of effective dose rates for both the adultand the newborn (and thus for all ages).
(177) The expected applications of the dose rate coefficients are: (a) pre-accidental
evaluations in order to predict the possible impacts to the public by postulated radiologicalaccidents, (b) post-accidental evaluations to estimate doses in order to develop a radiologicalprotection strategy for the exposed populace, (c) evaluations following discharge ofradionuclides from nuclear and radioisotope facilities during routine operations, and (d)evaluations of naturally occurring radionuclides in the environment. The pre/post-accident
analyses are performed typically by software packages (e.g. codes for severe accidents). The
software predicts the dispersion, migration, and distribution of radionuclides in theenvironment. The dose rate coefficients of the present publication could thus be implemented
within these codes.
(178) It should be noted that dose rate coefficients are calculated for idealised andhypothetical source geometries such as semi-infinite and uniform distributions, for reference
phantoms wearing no clothing, and for an idealised, upright postures, even for the exposed
newborn. As a result, they do not fully reflect actual exposures for any particular situation or
exposed individual.
(179) External doses can be significantly lower indoors than outdoors due to the shielding
effects of the building. This is taken into account through the use of a so-called location factorof 0.4-0.6 which accounts for structural shielding by building type (according to the country,
93

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2208
2209
2210
2211
2212
2213
2214
2215
2216

building material) and an assumed occupancy factor of 0.6 (i.e. approximately two thirds ofthe time per day spent indoors) which represents the fraction of time spent inside a house(IAEA, 2000a). This obviously can vary considerably according to the geographicaldistribution, profession and population habits. The present report presents dose coefficients
rates for situations outside houses and does not attempt to address issues of shielding or
population behaviour. The selection and application of suitable location and occupancy
factors is left to the user (i.e. the legislative authority or the developer of emergency
programs).

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2217

REFERENCES

2218
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2239
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2247
2248
2249
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2253
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2257
2258
2259
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2261
2262

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ANNEX A. SKELETAL DOSIMETRY

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(A 1) In this report, the radiation absorbed dose to two different target tissues wereassessed in the computation of the effective dose: the haematopoietically active bone marrow(AM), and the skeletal endosteum (TM50). The former target region is taken as the nonadipose regions of the bone marrow cavities within both spongiosa and medullary marrowcavities of the phantom skeleton, while the latter target region is taken to be total marrow
localised with 50 μm of the bone trabeculae surfaces and along the interior surfaces of thelong bone medullary cavities. As described in Publications 110 and 116 (ICRP, 2009, 2010),
the bone trabeculae and marrow cavities are tissue structures on the order of tens to hundredsof micrometres in thickness and extent, and thus cannot be fully modelled with the voxel
resolution of either the reference adult or paediatric phantoms. Consequently, radiation
absorbed dose, thus equivalent dose, to these two target tissues were determined employing
the concept of the fluence-to-dose response function for photons as described and presented in
Annex D of Publication 116 (ICRP, 2010).
(A 2) It should be noted that for this report, energy deposition to the skeletal target tissues
is almost exclusively by photons, either directly emitted from the environmental radionuclide
sources (air, water, or soil), or indirectly by bremsstrahlung x-ray production byenvironmentally emitted beta particles and conversion/Auger electrons. In the rare instancethat electron collisional kinetic energy is deposited within the marrow cavities of the phantom
skeleton, radiation dose to spongiosa (or medullary marrow) is taken as a surrogate of theabsorbed dose to either AM or TM50.
(A 3) The fluence-to-dose response function ( ℛ ) for assessment of the bone-specificabsorbed dose to skeletal tissues delivered by photons of energy (E) in bone site (x) is given
as follows:ℛ(𝑟𝑟𝑇𝑇 ⟵ 𝑟𝑟𝑆𝑆 , 𝑥𝑥, 𝐸𝐸) =

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=�
𝑟𝑟

𝐷𝐷(𝑟𝑟𝑇𝑇 , 𝑥𝑥)
Φ(𝐸𝐸, 𝑟𝑟𝑠𝑠 , 𝑥𝑥)

(A.1)

∞
𝑚𝑚(𝑟𝑟, 𝑥𝑥)� � 𝜙𝜙(𝑟𝑟𝑇𝑇 ⟵ 𝑟𝑟, 𝑇𝑇𝑖𝑖 , 𝑥𝑥)(𝜇𝜇𝑖𝑖 ⁄𝜌𝜌)𝑟𝑟,𝐸𝐸 𝑇𝑇𝑖𝑖 𝑛𝑛𝑟𝑟 (𝑇𝑇𝑖𝑖 , 𝐸𝐸) 𝑑𝑑𝑇𝑇𝑖𝑖
𝑚𝑚(𝑟𝑟𝑇𝑇 , 𝑥𝑥)
0
𝑖𝑖

(A.2)

where
x is the index for the various bone sites within the phantom (upper femora, cranium, etc.); forthe long bones, regions of spongiosa and the medullary cavities are considered as different
bones sites;rT is the index for the target tissue for dose assessment (active marrow or endosteum);rS is the index for the source tissue in bone site x in which the photon fluence is scored(spongiosa or medullary marrow);r is the index for the constituent tissues of source tissue rS. For rS = spongiosa, r is trabecularbone, active marrow, or inactive marrow;
E is the energy of the photon passing through and potentially interacting within skeletal tissuerS of bone site x;𝑚𝑚(𝑟𝑟, 𝑥𝑥) is the mass of the constituent tissue r in bone site x;𝑚𝑚(𝑟𝑟𝑇𝑇 , 𝑥𝑥) is the mass of the target tissue rT in bone site x;
i is the index for the photon interaction type considered: photoelectric, Compton, pair
production, or triplet production;

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Ti is the kinetic energy of the secondary electron liberated in constituent tissue r by interaction
type i;𝜙𝜙(𝑟𝑟𝑇𝑇 ⟵ 𝑟𝑟, 𝑇𝑇𝑖𝑖 , 𝑥𝑥) is the fraction of secondary electron kinetic energy Ti liberated in constituent
tissue r of bone site x that is imparted to target tissue rT in bone site x;(𝜇𝜇𝑖𝑖 ⁄𝜌𝜌)𝑟𝑟,𝐸𝐸 is the mass attenuation coefficient for photon interaction type i, in constitute tissue
r at photon energy E; and𝑛𝑛𝑟𝑟 (𝑇𝑇𝑖𝑖 , 𝐸𝐸)𝑑𝑑𝑇𝑇𝑖𝑖 denotes the number of secondary electrons of energy between Ti and Ti + dTi
liberated in constituent tissue r by photon of energy E in interaction type i.
(A 4) As noted in Annex D of Publication 116, Eq. D.2 was evaluated as described by
Johnson et al. (Johnson et al., 2011). Electron absorbed fraction data were obtained throughPaired-Image Radiation Transport (PIRT) calculations using microCT images of 32 bones
sites extracted from the skeleton of a 40-year-old male cadaver (Hough et al., 2011). Valuesof electron absorbed fractions in the bones of the reference paediatric phantoms were takenfrom the University of Florida doctoral dissertations of Pafundi (Pafundi, 2009) and Wayson(Wayson, 2012), as summarised in Bolch et al. (in preparation). MicroCT images of cadaveric
newborn bones were used for radiation transport in the bones of the reference newborn
phantom (Pafundi et al., 2009; Pafundi et al., 2010). Similarly, microCT images of cadaveric
18-year-old male bones were used in the construction of skeletal absorbed fractions forelectrons in the reference 15-year-old phantom (Pafundi, 2009). Cadaveric bone samples were
not available for the interior ages of the ICRP reference phantom series. Consequently, thelinear path length distributions from the University of Leeds 1.7-year-old and 9-year-old
cadavers were used respectively to assess electron absorbed fractions in the bones of thereference 1-year-old and 10-year-old phantoms (Beddoe, 1976). Values of skeletal electron
absorbed fractions were then assessed via interpolation of the Leeds data to report values forthe reference 5-year-old phantom (Pafundi, 2009). Charged particle equilibrium is typicallyestablished across bone sites at photon energies exceeding 200 keV, and thus in this report,
values of the dose response function above that energy are taken as their corresponding
spongiosa kerma coefficients.
(A 5) In this report, the absorbed dose in tissue (rT) in bone site (x), 𝐷𝐷(𝑟𝑟𝑇𝑇 , 𝑥𝑥) is thus
determined as the integral of the product of the bone-specific energy-dependent photon
fluence ( Φ(𝐸𝐸, 𝑟𝑟𝑠𝑠 , 𝑥𝑥) ) and the bone-specific energy-dependent dose-response function(ℛ(𝑟𝑟𝑇𝑇 ⟵ 𝑟𝑟𝑆𝑆 , 𝑥𝑥, 𝐸𝐸)):
𝐷𝐷(𝑟𝑟𝑇𝑇 , 𝑥𝑥) = � Φ(𝐸𝐸, 𝑟𝑟𝑠𝑠 , 𝑥𝑥) ℛ(𝑟𝑟𝑇𝑇 ⟵ 𝑟𝑟𝑆𝑆 , 𝑥𝑥, 𝐸𝐸)𝑑𝑑𝑑𝑑 .

(A.3)

E

While bone-specific absorbed dose to the skeletal tissues was computed in this study, thecomputation of the effective dose requires the skeletal-averaged absorbed dose to active
marrow and to endosteum for each of the reference adult and paediatric phantoms.
Accordingly, skeletal averaged dose is given as a mass-weighted average of the bone-site
specific absorbed dose:
𝐷𝐷𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (𝑟𝑟𝑇𝑇 ) = �𝑥𝑥

𝑚𝑚(𝑟𝑟𝑇𝑇 , 𝑥𝑥)
𝐷𝐷(𝑟𝑟𝑇𝑇 , 𝑥𝑥),𝑚𝑚(𝑟𝑟𝑇𝑇 )

(A.4)

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where 𝑚𝑚(𝑟𝑟𝑇𝑇 , 𝑥𝑥) is the bone-specific mass of the target tissue (rT) in bone site (x), 𝑚𝑚(𝑟𝑟𝑇𝑇 ) is thetotal mass of target tissue (rT) across the entire skeleton, and 𝐷𝐷(𝑟𝑟𝑇𝑇 , 𝑥𝑥) is the bone-specificabsorbed dose given by Equation A.3. Masses for the skeletal tissues are reported in
Publication 133 (ICRP, 2016) for the male and female reference adult phantoms, and in
Publication XXX (ICRP, in preparation) for the series of male and female pediatricphantoms.

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A.1. References

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2594
2595
2596
2597
2598
2599
2600
2601
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2604
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Beddoe, A.H., 1976. The microstructure of mammalian bone in relation to the dosimetry ofbone-seeking radionuclides. Department of Medical Physics, University of Leeds.
Bolch, …, in preparation.
Hough, M., Johnson, P., Rajon, D., Jokisch, D., Lee, C. and Bolch, W., 2011. An image-basedskeletal dosimetry model for the ICRP reference adult male-internal electron sources. Phys.
Med. Biol. 56, 2309-2346.
ICRP, 2009. Adult Reference Computational Phantoms. ICRP Publication 110, International
Commission on Radiological Protection, Oxford, UK. Ann. ICRP 39 (2).
ICRP, 2010. Conversion Coefficients for Radiological Protection Quantities for External
Radiation Exposures. ICRP Publication 116, International Commission on RadiologicalProtection, Oxford, UK. Ann. ICRP 40 (2-5).
ICRP, 2016. The ICRP Computational Framework for Internal Dose Assessment for
Reference Adults: Specific Absorbed Fractions. ICRP Publication 133, International
Commission on Radiological Protection, Oxford, UK. Ann. ICRP 45 (2).
ICRP, in preparation.
Johnson, P.B., Bahadori, A.A., Eckerman, K.F., et al., 2011. Response functions forcomputing absorbed dose to skeletal tissues from photon irradiation - an update. Phys. Med.
Biol. 56, 2347-2365.
Pafundi, D., Lee, C., Watchman, C., Bourke, V., et al., 2009. An image-based skeletal tissue
model for the ICRP reference newborn. Phys. Med. Biol. 54, 4497-4531.
Pafundi, D., Rajon, D., Jokisch, D., et al., 2010. An image-based skeletal dosimetry model for
the ICRP reference newborn--internal electron sources. Phys. Med. Biol. 55, 1785-1814.
Pafundi, D.H., 2009. Image-based skeletal tissue and electron dosimetry models for the ICRP
reference pediatric age series. Biomedical Engineering, University of Florida, PhD
Dissertation.
Wayson, M.B., 2012. Computational internal dosimetry methods as applied to the University
of Florida series of hybrid phantoms. Biomedical Engineering, University of Florida,
Dissertation.

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ANNEX B. SKIN DOSIMETRY

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2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
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2642
2643
2644
2645
2646
2647
2648
2649
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2668

(B 1) For environmental external exposures and dose to the skin, stochastic effects are
relevant. In radiation protection, the mean value of the absorbed dose averaged over the
specified organ, tissue or cells at risk is correlated with the detriment due to stochastic effects.
The skin cells at radiogenic risk have been identified and the absorbed dose to these cells havebeen assigned a tissue weighting factor wT=0.01 (ICRP, 2007). The skin dose contributing to
the effective dose is the equivalent dose to the skin cells at risk averaged over the body.
(B 2) The skin cells at the most radiogenic risk are the basal cells, which are locatedbetween the epidermis and dermis of the skin. ICRP refers to a range of epidermal thicknessof 20 to 100 µm, including the majority of body sites, but uses the nominal average value of
70 µm for general radiological protection purposes (ICRU, 1997; ICRP, 2010). Publication
89 (ICRP, 2002) provides the reference thicknesses of the epidermis for different ages: 45 µm(newborn and 1-year-old and 5-year-old children), 50 µm (10-year-old children), 60 µm (15year-old children) and 70 µm (adults). A range of 50 to 100 µm below the skin surface isconsidered to be an appropriate depth for the basal cell layer at radiogenic risks of most partsof the skin (ICRP, 2010).
(B 3) The extent to which the mean value of the skin dose is representative of theabsorbed dose to the critical region of the skin, located at 50 to 100 µm depth, depends, forexternal irradiation, on the homogeneity of the exposure and on the range of the incident
radiation. For gammas of energies relevant for environmental radionuclides, the assumptionof the mean organ dose being representative of the dose to the 70 µm can be considered valid
due to their rather homogeneous dose distribution within the skin. For weakly penetratingradiations (e.g. electrons) which could exhibit a significant dose gradient within the skin, thisapproach could be invalid, underestimating or overestimating the doses to the basal cell layer
at risk.
(B 4) The skin of the voxel–based ICRP reference phantoms is represented as one voxel
layer. The voxel thicknesses in both the male and female adult phantoms (2.137 mm and1.775 mm, respectively) (ICRP, 2009) are larger than the reference skin thicknesses of 1.6
mm and 1.3 mm for the reference male and female, respectively (ICRP, 2002). Reference
values for skin thickness in children have not be defined by ICRP, but can be derived for thereference paediatric phantoms using Publication 89 data on: (1) skin mass and (2) bodysurface area provided in Publication 89 (ICRP, 2002), and (3) a reference skin density fromICRU Report 46 (ICRU, 1992). These derived skin thicknesses are shown in Table B.1. Notethat these have not directly been used for the skin dosimetry of this publication, as the skindose was scored at the sensitive layer (see paragraph B7), but are referred here for the sake ofcompleteness.
(B 5) For electron skin dosimetry of the adult phantoms, the voxel representation of 2.1 or
1.7 mm (for male and female phantoms, respectively) could underestimate or overestimate thedoses, depending on the electron energy, as would be shown in section B.1.1. In order toovercome this limitation, polygon mesh (PM) models were used: for the adult male andfemale phantoms, the skin models of the mesh-type ICRP adult reference phantoms were
employed for the calculations. These phantoms are the exact counterparts of the ICRP
phantoms and have the advantage that they can model small tissues below the voxel phantom
resolution. More information on these phantoms can be found at (Kim et al., 2011, 2016,2017; Yeom et al., 2013, 2016a,b; Nguyen et al., 2015).
(B 6) The mesh-type skin models of the adult phantoms were constructed by directly
converting the skin models of the voxel-type ICRP adult reference phantoms to high-quality
polygon-mesh (PM) format. The PM skin models include a 50-µm -thick radiosensitive layer
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located at a depth from 50 to 100 μm below the skin surface. Fig. B.1 shows a 3D
representation of the adult male and female PM skin model. The masses of the adult PM skinmodels are in accordance with the reference values (male: 3300 g and female: 2300 g) (ICRP,
2002). The average thicknesses of the skin models are 1.69 mm and 1.33 mm for the adultmale and female, respectively, which are in good agreement with the reference values (male:
1.6 mm and female: 1.3 mm). The inner space of the skin PM models is filled with theaverage soft tissue for adults, as specified by ICRU (1992), but has slightly modified densities(male: 1.024 g cm3 and female: 1.010 g cm3) in order to maintain the reference body weightsof 73 (male) and 60 kg (female).

2678
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2683

Fig. B.1. Representation of the adult male and female polygon mesh (PM) skin model. Red
indicates the target sensitive layer of the skin; the beige colour indicates the exterior skinsurface and the black colour represents the most inner skin surface. The dead skin layer
between the exterior surface and the target layer is represented by the green colour, as viewed
from the left side.

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(B 7) For the paediatric phantoms, the mesh-type skin models were constructed from theouter surfaces of the NURBS-version of ICRP paediatric phantoms. (NURBS: Non-Uniform
Rational B-Spline surfaces). These were the original phantoms from which the ICRP
paediatric phantoms were derived (Lee et al., 2010). The NURBS-format outer surfaces wereconverted to the PM format via tessellation procedure (Piegl and Richard, 1995). The PM
outer surfaces were then adjusted to match the total volumes of the ICRP paediatricphantoms. The outer surfaces were copied and their sizes were reduced to define the innersurface of the skin, matching the skin thicknesses to those (i.e. voxel sizes) of the ICRP
paediatric phantoms. The inner space of the PM skin models was also filled with average soft
tissue (ICRU, 1989) but with slightly modified densities to maintain the reference bodyweights. The outer surfaces were again copied to create two additional surfaces and reduce
their sizes to define the target sensitive layer within the skin at depths of 50 μm and 100 μm.
Table B.1 shows the average skin thickness, mass and density for the paediatric phantoms, aswell as the of the sensitive layer of the skin.

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Table B.1. Skin thickness, mass and density and mass of the sensitive layer of the skin of thepediatric phantoms.

Age and gender

Newborn 1 yr
Male/
Male/

5 yr

10 yr

Male/

Male/

15 yr

15 yr
Male

FemaleFemale Female Female Female

Skin thickness (mm)

0.663

0.663

0.850

0.990

1.200

1.250

Skin mass (g)

139.9

291.5

665.5

1221.81978.72236.0Mass of sensitive layer (g) 10.7

22.2

39.5

62.3

83.3

90.4

Skin density (g cm-3)

1.1

1.1

1.1

1.1

1.1

1.1

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(B 8) The skin dose rate coefficients, shown in the electronic supplement of this reportand used for the calculation of the effective dose rates, for both electron and photon beams
and all geometries, were derived using the above PM phantom models and the Monte Carlocode GEANT4 (Agostinelli et al., 2003). For implementation, the skin phantoms in the PMformat were converted to the tetrahedral-mesh (TM) format using the TetGen code (Si, 2006)
and the converted TM phantoms were implemented in GEANT4 using the G4Tet class. Notethat this tetrahedralization maintains the original shape of the PM phantoms but significantly
improves computation speed (Yeom et al., 2014). The electromagnetic physics library of
G4EmLivermorePhysics was used to transport photons and electrons (Wright, 2014).
Considering the 50-μm-thick target layer, a secondary-range cut value of 1 μm was set for allparticles.
(B 9) It should be noted that tissue reactions (sometimes referred to as deterministic
effects) are correlated to the local skin dose i.e. dose averaged over 1 cm2. The skin dosecoefficients given in this report are not correlated with tissue reactions since they have been
evaluated for the skin extended in the whole body.

2719

B.1. Electron

2720
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(B 10) Fig. B.2 and B.3 show the skin dose rate coefficients for the adult female phantom
and contamination at the surface of the soil and submersion to contaminated air, respectively,
as a function of electron energy and as calculated using the original voxel phantom coupled to
the PHITS transport code (Sato et al., 2013) and the polygon mesh phantom and the GEANT4
code (Agostinelli et al., 2003). As mentioned above, the resolution of the voxel phantom does
not allow targeting the cells at risk (50 – 100 μm layer) but instead the dose is computed forthe whole skin voxels. Using the mesh phantom, the estimation of the dose rate coefficients tothe sensitive as well as to the entire skin is possible and these are shown in the Figures B.2
and B.3. It can be seen, that, the voxel approach overestimates the absorbed dose to the skinbasal cell layer at photon energies below approximately 0.100 MeV and underestimates thatsame dose at energies between 0.100 and 1.5 MeV.

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-1

10-2

Skin equivalent dose rate (nSv h Bq m )

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2743
2744
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2746
2747
2748
2749

10-3
10-4
10-5
Voxel-entire skin (PHITS)
Mesh-entire skin (GEANT4)
Mesh-sensitive layer (GEANT4)

10-6
10-7
10-8
0.01

0.1

1

10

Electron energy (MeV)

Fig. B.2. Skin dose coefficients for the adult female phantom and contamination at the surfaceof the soil, calculated using the original adult voxel phantom and the PHITS code, and thepolygon adult mesh phantom and the GEANT4 code.
Skin equivalent dose rate (nSv h-1 Bq-1 m3)

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2734
2735
2736
2737

Soil contamination, electron sources
Adult female

101
100

Air submersion, electron sources
Adult female

10-1
10-2
10-3
10-4
10-5

Voxel-entire skin (PHITS)
Mesh-entire skin (GEANT4)
Mesh-sensitive layer (GEANT4)

10-6
10-7
10-8
0.01

0.1

1

10

Electron energy (MeV)

Fig. B.3. Skin dose coefficients for the adult female phantom and air submersion, calculatedusing the original adult voxel phantom and the PHITS code, and the polygon adult meshphantom and the GEANT4 code.
(B 11) For electron simulations in the case of water immersion, excessive computation
times are needed, because electrons emitted from the spherical water source of a diameter of 2
m hardly reach the phantom. To improve the efficiency of the calculation, a sampling source
volume was limited from the skin surface to a certain distance in the water, depending onelectron energies. For electrons with energies > 0.06 MeV, a distance, which is longer thanthe electron CSDA range in the water medium was used to limit the sampling source volume,
because these primary electrons contribute to most of the energy deposited to the skin107

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100

-1

10-1

-1

sensitive layer. On the other hand, for the lower energy electrons (≤ 0.06 MeV), a distance,
which is longer than the mean free path of the photon at the initial electron energy, wasconsidered because these electrons, having CSDA range less than 50 μm, cannot penetrate the
50-μm-thick dead layer to reach the skin sensitive layer and thus, only the secondary photons(e.g. bremsstrahlung photons) contribute to the dose.
(B 12) Figures B.4-B.6 show the skin dose rate coefficients evaluated for the sensitive layerof the skin using the mesh phantoms, for all ages and geometries considered. For the adult and15-year-old phantoms, the male and female coefficients were averaged, whereas for the otherpaediatric ages a single skin model was used.

10-2

Skin equivalent dose rate (nSv h Bq m )

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2759

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2766

10-3
10-4
10-5
10

Adult
15 years
10 years
5 years
1 year0 years

-6

10-7
10-8
10-9
0.01

0.1

1

10

Electron energy (MeV)

Fig. B.4. Skin dose rate coefficients for monoenergetic electron sources distributed at thesurface as a ground plane source.
Skin equivalent dose rate (nSv h-1 Bq-1 m3)

2760
2761
2762
2763

Soil contamination, electron sources

101
100

Air submersion, electron sources

10-1
10-2
10-3
10-4

Adult
15 years
10 years
5 years
1 year0 years

-5

10

10-6
10-7
10-8
0.01

0.1

1

10

Electron energy (MeV)

Fig. B.5. Skin dose rate coefficients for monoenergetic electron sources distributed uniformly
in the atmosphere.

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-1

10-3
10-4

Skin equivalent dose rate (nSv h Bq m )

10-2

-1

2767
Water immersion, electron sources

10-5
10-6
Adult
15 years
10 years
5 years
1 year0 years

10-7
10-8
10-9
10-10
10-11
0.01

1

0.1

10

Electron energy (MeV)

2768
2769
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2771

Fig. B.6. Skin dose rate coefficients for monoenergetic electron sources distributed uniformly
in the water (i.e. water immersion).

2772

B.2. Photons

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(B 13) Figures B.7-B.9 show the skin dose rate coefficients for the adult male phantom, formonoenergetic photons and for the three environmental sources considered in this publication.
For each plot, results are shown as calculated with the voxel-defined entire skin (i.e. averaged
over all skin voxels), the entire skin as defined by the polygon meshes and the sensitive layerof the skin, also polygon-mesh defined and targeted between 50 and 100 μm below the skinsurface. Similarly to the electron exposure simulations, the calculations for the voxel
phantoms were performed with PHITS (Sato et al., 2013), whereas for the mesh phantoms
GEANT4 was used (Agostinelli et al., 2003). It can be seen, that, although the differences of
evaluated coefficients are not so pronounced as for electrons, the values of the coefficients forthe sensitive layer are higher than those of the entire skin, at energies below approximately
0.1 MeV. This pattern is seen because low-energy photons tend to establish their maximum
dose near the skin surface, as the dose rapidly decreases with depth by exponential
attenuation. However, the values of the coefficients for the sensitive layer are lower for
emitted energies above 0.2 to 0.6 MeV, (depending on the environmental source). Photons
penetrate the sensitive layer skin region and deposit their energy partially, while they fully
impart their energy to the voxel skin of the voxel phantoms, establishing the maximum doseat a depth deeper than what is seen within the sensitive layer.
(B 14) Moreover, it should be noted that, while the skin dose rate coefficients obtained withthe adult voxel phantoms with PHITS and EGS4 agree well (see section 6.5), GEANT4 givesslightly larger values in the low energy region. This might result from the differences in the
cut-off algorithm during particle transport within each code.

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2800
2801
2802

Soil contamination, photon sources at 0.0 mfp
Adult male
10-2

10-3
Voxel-entire skin (PHITS)
Mesh-entire skin (GEANT4)
Mesh-sensitive layer (GEANT4)
10-4
0.01

0.1

1

10

Photon energy (MeV)

Fig. B.7. Skin dose rate coefficients for monoenergetic photon sources distributed at thesurface as a ground plane source.
Skin equivalent dose rate (nSv h-1 Bq-1 m3)

2795
2796
2797
2798

10-1

101

100

Air submersion, photon sources
Adult male

10-1

10-2
Voxel-entire skin (PHITS)
Mesh-entire skin (GEANT4)
Mesh-sensitive layer (GEANT4)

10-3

10-4
0.01

0.1

1

10

Photon energy (MeV)

Fig. B.8. Skin dose rate coefficients for monoenergetic photon sources distributed uniformly
in the atmosphere.

110Skin equivalent dose rate (nSv h-1 Bq-1 m3)

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2816
2817

Water immersion, photon sources
Adult male

10-3

10-4

10-5
Voxel-entire skin (PHITS)
Mesh-entire skin (GEANT4)
Mesh-sensitive layer (GEANT4)

10-6

10-7
0.01

1

0.1

10

Photon energy (MeV)

Fig. B.9. Skin dose rate coefficient for for monoenergetic photon sources and water
immersion.
(B 15) Figures B.10-B.12 show the skin dose rate coefficients evaluated for the sensitive
layer of the skin using the mesh phantoms, for all ages and environmental sources considered,for monoenergetic photons. As for the coefficients for electrons, for the adult and 15-year-old
phantoms, the male and female coefficients were averaged, whereas for the other paediatricages a single skin model was used. All skin dose rate coefficients, also for soil contamination
at depths of 0.2-4 mfp in the soil, can be found in the electronic supplement.
Skin equivalent dose rate (nSv h-1 Bq -1 m2 )

2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814

10-2

10-1

Soil contamination, photon sources at 0.0 mfp

10-2

10

Adult
15 years
10 years
5 years
1 year0 years

-3

10-4
0.01

0.1

1

10

Photon energy (MeV)

Fig. B.10. Skin dose rate coefficients for monoenergetic photon sources distributed at thesurface as a ground plane source.

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Air submersion, photon sources

100

10-1
Adult
15 years
10 years
5 years
1 year0 years

10-2

10-3

10-4
0.01

0.1

1

10

Photon energy (MeV)

Fig. B.11. Skin dose rate coefficients for monoenergetic photon sources distributed uniformly
in the atmosphere.
10-2

Water immersion, photon sources

-1

-1

3

Skin equivalent dose rate (nSv h Bq m )

2818
2819
2820
2821

101

10-3

10-4
Adult
15 years
10 years
5 years
1 year0 years

10-5

10-6
0.01

0.1

1

10

Photon energy (MeV)

2822
2823
2824
2825
2826

Fig. B.12. Skin dose rate coefficients for monoenergetic photon sources distributed uniformly
in the water (i.e. water immersion).

2827

B.3. References

2828
2829
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2831
2832

Agostinelli, S., Allison, J., Amako, K., et al., 2003. Geant4—a simulation toolkit. Nuclear
Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers,
Detectors and Associated Equipment 506(3), 250-303.
ICRP, 2002. Basic Anatomical and Physiological Data for Use in Radiological Protection:
Reference Values. ICRP Publication 89, Pergamon Press, Oxford, UK. Ann. ICRP 32 (3-4).
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ANNEX C. CONTENT OF THE ELECTRONIC SUPPLEMENT

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(C 1) The electronic supplement of this report presents age-dependent reference dose rate
coefficients of effective dose and organ equivalent doses for the three environmental
exposures simulated (1) soil contamination on the soil (0.0 mfp) and in the soil (planarsources at depths of 0.2, 1, 2.5 and 4 mean free paths of photon energy), (2) submersion tocontaminated air and (3) immersion to contaminated water. The coefficients have been
evaluated for the ICRP reference adult and paediatric phantoms using the methods describedin sections 4-7.
(C 2) For soil contamination, additional data are given for the effective and organ
equivalent dose rate coefficients for planar sources at specific depths of 0.5, 3.0, and 10.0 g
cm-2 computed as described in section 8.1.
(C 3) Also given are the effective and organ equivalent dose rate coefficients for photon
sources exponentially distributed with 𝛽𝛽 = 0.5, 1.0, 2.5, and 5.0 g cm-2 as discussed in 8.1.
(C 4) Data are given for every age group and for the male and female phantoms
separately. The effective and organ equivalent dose rate coefficients are normalized toenvironmental radioactivity concentration and are given in units of nSv h-1 Bq-1 m-2 (for soil
contamination) or nSv h-1 Bq-1 m-3 (for submersion to contaminated air and water immersion).
(C 5) The supplement is organised in three main folders (one for each exposure
geometry): ‘Soil contamination’, ‘Air submersion’ and ‘Water immersion’. The folder ‘Soil
contamination’ contains 7 subfolder: 5 for each mean free paths considered, and 2 for planarand exponential sources. The folders of the planar and exponential sources contain 3
subfolders for each specific depths at 0.5, 3.0, and 10.0 g cm-2, and 4 subfolder for photon
sources exponentially distributed with 4 different relaxation masses per unit area, 𝛽𝛽 = 0.5,
1.0, 2.5, and 5.0 g cm-2, respectively.
(C 6) All data are given in two different formats: ASCII format and Microsoft Excel
Format.
(C 7) Reference values of the organ equivalent dose rate coefficients are given for thefollowing organs: bone-marrow (red), colon, lung, stomach, breast, ovaries, testes, bladder,oesophagus, liver, thyroid, skeletal endosteum, brain, salivary glands, skin, remainder tissues,
adrenals, extrathoracic (ET) region, gall bladder, heart, kidneys, lymphatic nodes, muscle,oral mucosa, pancreas, prostate, small intestine, spleen, thymus, and uterus/cervix.
(C 8) Moreover, a data viewer code is provided which allows comfortable viewing anddownloading of the organ and effective dose rate coefficients.

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