Comments from the Dutch National Institute for Public Health and the Environment (RIVM)
T. van Dillen and R.O. Blaauboer
Part 1: General and major remarks
This is the first time the ICRP publishes age-dependent dose coefficients (DCs) for external exposures of members of the public to environmental sources of ionizing radiation: ground contamination, air submersion and water immersion. We appreciate ICRP’s efforts to provide the radiation-protection community with improved ‘tools’ to perform dose assessments and we compliment the authors with this publication. It is well written and offers an excellent insight into the calculation techniques used to derive these coefficients, understandable for non-experts. Similar to the dose coefficients for the intake of radionuclides (inhalation, ingestion), DCs for external, environmental radiation are now dependent on the age category of the exposed individual. We especially appreciate the provided radionuclide-specific coefficients that relate the environmental contamination levels with the environmental monitoring quantities such as the ambient dose equivalent rate. This is particularly useful in emergency preparedness and response.
However, to our opinion, this draft publication could significantly benefit from consideration of the issues raised below. We hope to see these issues being addressed in the final version of this publication.
1) Organ absorbed dose rate coefficients can be determined with high accuracy by the Monte-Carlo simulation technique involving high-resolution voxel phantoms. However, upon conversion of these “accurately determined physical dose rate coefficients” to the risk-related, effective dose rate coefficients, at least part of the accuracy is canceled out by the relatively large uncertainty concealed in (the determination of) the tissue weighting factors. As effective dose is only an approximate indicator of the possible, stochastic health risks related to exposure to internal or external radiation sources (determined for sex-averaged Reference Persons of specified ages), the inherent uncertainty hidden within this radiological protection quantity and its underlying assumptions (e.g. LNT) is generally known and accepted for use within the pragmatic system of radiation protection.
With this in mind and realizing that effective dose is not a suitable quantity for individual risk assessments, one could argue whether or not the system of radiation protection significantly benefits from the (increasingly) higher degree of accuracy in the dosimetric calculations as presented in this Publication. These issues should be discussed here as well and placed in context with the fact that the same set of (sex and age-averaged) tissue weighting factors is employed in the calculation of the effective dose rate coefficients for each age category, from newborns to adults. The latter critique on the use of a unique set of tissue weighting factors for all age categories was also addressed in the draft Publication on “The use of the effective dose as a radiological protection quantity” (ICRP, 2018 in press) but was never elucidated. Consequently, the effective doses derived for various age groups may not necessarily reflect the risks for that particular age-group properly. Instead, the ICRP may need to consider age-dependent tissue weighting factors for the age-dependent effective dose rate coefficients.
A clarification of these issues would be very helpful in the understanding of how to apply the coefficients and of the interpretation of the outcome of the age-related dose assessment (and their limitations).
2) As follows from Section 4, the voxel resolution of the paediatric phantoms is much higher than that of the adult reference computational phantoms. As an example, the total size of the matrix decreases from 56.5 million voxels for the 15-year male phantom to 1.95 million voxels for the adult male phantom. This raises questions whether differences in dose rate coefficients between these age categories result from these differences in resolution, especially at low energies of exposure. The uncertainties with respect to voxel dimensions should therefore be mentioned.
3) Uncertainties with respect to the actual Monte-Carlo calculation technique are described in detail in the current draft. Resulting dose rate coefficients are listed as values with three significant digits for the idealized and conservative exposure and geometries regarded in this publication.
However, in reality, exposure situations are never as idealized and conservative as considered here. There may for instance be shielding from vegetation, clothing or buildings. Moreover, large(r) uncertainties in the environmental monitoring data may exist by which dose estimations become more uncertain as well. These issues are not addressed sufficiently in the current draft and should be indicated as well.
4) This publication describes – in detail and on a basic level - how the Monte-Carlo calculations are performed. However, the description of the final data as visualized in the figures of Section 6 are, in general, rather brief and could benefit from extended explanation, thereby preventing incorrect interpretations of the presented data.
5) The abstract of this publication mentions that ground contamination may result from fall-out, e.g. resulting from a radiological incident or accident, or from naturally occurring terrestrial sources. Throughout the report, however, attention is only focused on ground deposition as a result of fall-out/deposition of airborne radioactivity from a radioactive plume. It would be better to describe this more generally as ground contaminant or ground contamination at specified depths instead of deposit or deposition, respectively.
Furthermore, soil or ground contamination - expressed in Bq/m2 - can be seen as a projected surface contamination whose value is independent of the exact depth distribution (of course the resulting dose rates are). This could be mentioned more clearly in the text.
6) This report should more clearly indicate and explain the difference between ‘conversion coefficients’, as used in Publication 116 (ICRP, 2010) for external, occupational exposures and ‘dose coefficients’ as used in this publication on environmental, external exposures of members of the public and as used for internal exposures. Please also define ‘conversion coefficient’ in the Glossary.
Note: the term ‘Dose Conversion Coefficient’ is also found in literature, whereas previously the term ‘Dose Conversion Factor’ was used. We advise the ICRP to mention these terms here as well and indicate which terms to use ‘when’ and which terms not to use at all.
7) Section 6.5 on the verification on the calculations is a rather technical section. Though very important, it does not contribute to the understanding of main concepts involved in the derivation of the dose coefficients and may therefore not be of great relevance to the general reader. This section actually reduces the readability of the document and hence we suggest to include this section as an Annex.
8) In section 7 the radionuclide-specific dose rate coefficients are calculated for the several exposure modes S (ground contamination, air submersion and water immersion). In fact, equation (7.1) describes the expression how the ‘previously calculated’ organ absorbed dose rates are used in the calculation of their radionuclide-specific counterparts. For exposure to soil contamination, the reader may get the wrong impression that the photon-related data presented in Tables 6.1 through 6.5 can be used directly in the calculation of equation 7.1. However, the data presented in Tables 6.1 through 6.5 are valid for a constant value of the mean free path in soil, mfp. This means that, as a function of ‘monoenergetically emitted energy’, the actual, physical depth in cm or g/cm2 (in soil) changes at a fixed value of mfp. Consequently, for a soil contamination with a specific radionuclide N at a fixed physical depth (cm or g/cm2), the emitted photon energies thus have a different depth-value expressed in terms of mfp. This means that one should first convert the actual contamination depth (in cm or g/cm2) to a corresponding value of ‘mfp’ for each emitted photon energy in the radionuclide’s emission spectrum. It is only after this conversion that one can use the data of the dose rate coefficients presented in Tables 6.1 through 6.5 at specified values of mfp (and typically by bi-interpolation - in energy and mfp - between values in these tables).
However, the data presented in tables 8.1 through 8.3 already provide dose rate coefficients as a function of the monoenergetically emitted photon energy at physical depths expressed in g/cm2. Data from these tables can thus be used more conveniently to derive the radionuclide-specific dose rate coefficients as a function of physical depth in the soil (i.e., one now only has to interpolate between the various discrete energies within the emission spectrum).
This discussion should be held in section 7.1 also referring to section 8.1.1 and the data presented in Tables 8.1-8.3. Moreover, this discussion also leads to the question of what the actual advantage is of listing dose rate coefficients at a constant value of mfp, as presented in Tables 6.1 through 6.5. This should be clearly mentioned in this Publication.
9) The ambient dose rate is briefly described in Section 8.4 and results are briefly presented in Section 6.6 for ground contamination at several depths in mfp. Without the actual publication being available from the ICRP yet and with the large amount of critique on the draft version for consultation last year, the ICRP could consider to remove this quantity ‘ambient dose rate’ (and the results) from the current publication on environmental exposures. If, however, the ICRP wishes to keep this quantity here anyway, more details and results should be given. Section 8.4 should be moved to an earlier section with more details (preferably to Section 3.4 on Operational quantities), whereas Section 6.6 should also provide results for air submersion. Values of this quantity should then also be added to Tables 6.1 through 6.5, 6.7 and 8.1 through 8.7. In addition, radionuclide-specific values for this quantity should then also be available from the electronic supplement.
10) In Section 8.1.2, dose rate coefficients for volumetric contamination sources in soil are calculated by means of an integration of planar sources over a certain depth profile, as given by equation (8.1) [the so-called weighted-integral method]. In Tables 8.4 through 8.7, results are listed for exponential profiles using several penetration depths/relaxations masses per unit area (beta=0.5, 1.0, 2.5 and 5.0 g/cm2), where integration is performed up to depths of 100 g/cm2.
Nothing is said about how the actual, numerical integration is performed: how many planar sources at certain depths (in g/cm2) are employed for the interpolation of the depth profile, how many integration steps are used, etc. Obviously, the data from Tables 8.1 through 8.3 are not sufficient to reconstruct the depth profiles from Tables 8.4 through 8.7. Results for planar sources, as in Table 8.1-8.3, should be given for additional depths (in g/cm2). In addition, for naturally occurring terrestrial sources, a uniform depth profile may be more appropriate. This could be modeled by a large value of beta >> 100 g/cm2 (upper integration boundary). Finally, a visualization of the data presented in Tables 8.1-8.7 would also be helpful.
11) Section 8.2 (Lines 2018 to 2061) on “Radionuclide decay chain” is almost an exact copy of the text in reference Eckerman and Ryman (1993, pages 195-196), Federal Guidance Report 12 and its recently updated version “Federal Guidance Report 15” (EPA-402/R18/001, June 2018). This should either be explicitly stated, or it should be at least partly rephrased. We also note that equation (8.5) seems to be incorrect. Since the effective dose is proportional to the time-integrated activity concentration, we would expect the term (1-exp[-lambda_j*T])/lambda_j inside the inner summation over index j.
12) This draft report is missing some practical examples of how to apply the dose rate coefficients – derived in this publication – in environmental dose assessments. The publication would benefit from more guidance on the use of these coefficients, by working out a few of such examples in an additional Annex. We refer to Appendix D (Example calculations) of the US EPA’s report entitled “External exposure to radionuclides in air water and soil” (Federal Guidance Report 15, EPA-402/R18/001, June 2018) for such example dose assessments.
Part 2: Detailed and editorial remarks
Abstract:
Units are incorrect: nSv h-1 Bq-1 m-2 or nSv h-1 Bq-1 m-3 --> nSv h-1 Bq-1 m2 or nSv h-1 Bq-1 m3
Main Points:
Page 8, Lines 22-24:
“These simulation 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”
-->
“These simulation results are then used to derive radionuclide-specific, organ absorbed and effective dose-rate coefficients, taking into account the radionuclide’s electron and photon emissions such as gamma-rays, conversion electrons, characteristic x-rays, Auger electrons, and bremsstrahlung x-rays”
Executive summary:
Page 10, Lines 91-93:
“The latter, following some modifications, have been selected in 2013 to become the reference ICRP paediatric phantoms”
A reference can be made to another ICRP draft report for consultation: “Paediatric Reference Computational Phantoms”
Page 10, Line 95 (also lines 2170 and 2640):
“… environmental radionuclides …” --> “… radionuclides in the environment …” or “ … radionuclides in environmental air, soil and water.”
Page 10, Line 96:
“… scattered photons in the environment …”
Also scattered photons from the human body (i.e., the voxel phantoms).
Page 10, Line 102-104:
Please mention that already in step 2, the organ equivalent and effective dose-rate conversion constants are evaluated for initially monoenergetic particles.
Glossary:
Page 11, Lines 131-133
Activity concentration in the IAEA Glossary and EU regulations (2013/59/Euratom) is in Bq/g or Bq/kg.
Line 132: “… per unit volume per of air or water …”--> “… per unit volume of air or water …”
Page 11, Lines 142-146:
“Ambient dose equivalent, H*(10)” --> “Ambient dose equivalent at a depth of 10 mm, H*(10)”
Ambient dose equivalent is more generally written as H*(d), with d the depth within the ICRU sphere. In this report, the choice is made for a depth of d =10 mm for environmental area monitoring (aiming at the assessment of the effective dose incurred by penetrating radiation).
Page 11, Lines 147:
The symbol for the ambient dose equivalent rate coefficient misses a superscript “*”. The “*” is used throughout the text though.
Page 13, Lines 186-189:
See issue 6 in ‘General and major remarks’ (part 1 of this review).
Page 16, Lines 316-322:
Relaxation mass per unit area: note that the soil depth z (Lines 318 and 319) is also expressed in units of g/cm2.
Page 17, Line 354:
“…radionuclides in the radioactive water.” --> “…radionuclides in water.”
1. Introduction
Page 18 , Line 361
“… from nuclear facilities …”
Not just nuclear facilities, but also e.g. the processing industry.
Page 18, Line 365:
“… in 1987 and…” --> “… in 1986 and…”
Page 18, Lines 375-378:
“However,… of the public.”: here it should be mentioned that the dominating contribution results from external radiation from deposited radionuclides on and in the ground/soil (so called groundshine).
Page 18, Lines 380-383:
ICRP Publications 56, 67, 69, 71 and 72 are all related to members of the public (i.e., parts 1 to 5), but the sentence continues with revisions for dose coefficients related to workers (OIR series). This is confusing.
Page 20, Line 429:
“… to expose member of the general public …” --> “… to expose members of the general public …”
Please add ‘s’
Pages 21-22, Lines 512-514:
It would be good to make a reference to the new ICRP draft report entitled “Paediatric Reference Computational Phantoms”, which is now under public consultation as well.
Page 22, Lines 518-520:
It does not become clear here whether or not dose-rate coefficients are already established in step 2 for these initially monoenergetic particles. Actually, the result of step 2 are dose-rate coefficients as a function of the energy of the initially monoenergetic particles emitted from the contaminated, environmental media, which serves as input for step 3.
Page 22, Line 529:
“… dose rate coefficients for monoenergetic particles …” -->
“… dose rate coefficients for initially monoenergetic particles …”
2. Schema for dose assessment from environmental exposure
Page 23, Lines 563-566:
“For example,… to children”
Please add a reference.
Page 23, Lines 577-579:
“In case of … depth profile”
See issue 5 in ‘General and major remarks’(part 1 of this review)
Page 23, Lines 588:
Fig. 2.2 --> Fig. 2.1
Page 24, Lines 601-604:
“After the … of the public”
This is true, however, in emergency response and planning, initial dose estimates based on the ambient dose equivalent H*(10) as a conservative estimate for the effective dose E is not uncommon either, especially in the case detailed information on the mixture of radionuclides is not (yet) available.
Page 24, Lines 617-630:
Para 24 is not (very) different from the method described in para 23, the only difference being the complexity of the contamination situation. Step DC3 is also performed, but taking into account - for instance - the inhomogeneity of the contamination situation.
Page 24, Lines 624-625:
”… ambient equivalent dose rate …” --> “… ambient dose equivalent rate …”
3. Dosimetric quantities used in radiological protection
Page 26, Lines 652-659 (para 27):
The symbol D_T,R used in equation (3.2) [Line 662] should already be mentioned in para (27) dealing with the organ absorbed dose.
In Line 658, “Absorbed dose D” is better written as “Mean absorbed dose” or “Organ absorbed dose”. Furthermore, dose limits to prevent deterministic effects are currently still expressed in the quantity organ equivalent dose (skin, lens of the eye, extremities).
Page 26, Line 670:
Only photons and electrons are treated in this report, so most of the table is unnecessary.
Page 27, Line 673
“… sum of tissue equivalent doses” --> “… sum of organ equivalent doses”
(use the same terms throughout the publication, in line with the “Glossary”, see Line 276)
Page 27, Line 683:
“… is Sievert (Sv)” --> “is sievert (Sv)”
Pages 27-28, Lines 704-712:
Please make a reference to the Publication entitled “The Use of Effective Dose as a Radiological Protection Quantity”, which is currently in preparation.
Page 28, Lines 735-739:
Please refer to the Glossary of this draft report for a definition of the quality factor Q.
4. The ICRP reference phantom
Page 31, Line 805:
“At lower energies …”
Lower than what? Please indicate the energy ranges.
5. Simulation of the environmental radiation field (step 1)
Page 35, Lines 924-926
“The first source … in the soil”:
As mentioned in the abstract of this publication, it may also simulate naturally occurring terrestrial sources (i.e., not just deposition/fall-out of airborne radioactivity). See issue 5 in ‘General and major remarks’ (part 1 of this review).
Page 35, Line 951:
“…short distance….”
Please give a typical value or range.
Page 36, Lines 967-970
Figure 5.1 also indicates secondary photons and scattered photons, while they are not mentioned in the main text. A brief description of these photons would be helpful to the reader.
Page 37, Line 1008:
“It simulates the deposition …” --> “It simulates the (deposition-related) concentration profile …”
Page 38, Lines 1034-1044 in combination with Line 1017:
As mentioned and explained, the soil density is taken as 1 g/cm3 (please change this to “1.0 g/cm3”. However, this is somewhat confusing when comparing with the soil-concentration value mentioned on Line 1017. One could change Line 1017 as follows:
“… which is equivalent to 5 mm of soil with density of 1.0 × 10^3 kg m-3”
Furthermore, para (63) uses both the units of g/cm3 and kg/m3. Please harmonize this and use one set of units instead, e.g., g/cm3
Page 38, Line 1053:
“Electron planar sources …” --> “Planar sources emitting electrons”
Pages 38-39, Lines 1055-1056:
“For electron sources, both electrons and secondary photons were transported”.
In Fig. 5.1 (right-hand side for electron sources), “secondary photons” are not in the list. What is meant here? Should ‘secondary photons’ be ‘secondary electrons’ in this sentence?
Secondary photons are mentioned in Fig. 5.1, but only on the left-hand side for photon sources.
Page 39, Lines 1075-1082:
Please include the mentioned elevation angle with respect to the horizontal plane to the sketch depicted in Fig. 5.2.
Page 39, Lines 1083-1085 in combination with Fig. 5.3 (Page 40):
Two comments here:
1) The bin of uncollided photons in left graph of Fig. 5.3 (at 0.5 MeV) is hardly visible, whereas it accounts for the largest portion of incident photons on the coupling cylinder. Please make this bin in Fig. 5.3 more visible.
2) Furthermore, it is stated that: “Overall, about 20% of the recorded photons on the coupling cylinder never interact with the air”. What is probably meant here is: ‘…never interact with the soil nor the air’ (this is because the source plane with the contamination is located at a certain depth of 0.2 mfp, which amounts to about 2 to 3 cm of soil for 0.5 MeV photons, see Fig.6.8 on page 60).
Page 39, Lines 1086-1092:
To be complete, please indicate the cylinder’s height range (as in Fig. 5.3) at which these spectra are recorded in Fig. 5.4 (even though the spectra are rather independent of height).
Page 40, Lines 1096-1100
Caption of Fig. 5.3: “(left) The y axis shows the number of photons per energy bin,…”
This is true, but the number of photons per energy bin is also divided by (1) the total number of photons within the indicated spectrum, and (2) the energy-bin size (in MeV). In this manner a probability density is obtained (in MeV-1) on the y-axis, which sums or integrates to a total value of 1.0 as explicitly indicated in the graph as well. A similar comment holds for the angular spectrum of Fig. 5.3.
Note: on Line 1098, please move the sentence’s full stop:
“per energy bin (right). The y axis shows” --> ”per energy bin. (right) The y axis shows”
Page 40, Lines 1103-1106:
Caption of Fig. 5.4: similar remark as above for the caption of Fig. 5.3 (Lines 1096-1100).
In each graph (1 mfp/left and 4 mfp/right), two spectra are plotted for uncollided and scattered photons, respectively. However, the integral value of 1.0 (as indicated in both plots, left and right) probably holds for the combination of both spectra, i.e., uncollided + scattered together? If so, this should be mentioned.
Page 40, Line 1116:
“… positioned below the plume; while, incident …” --> “… positioned below the plume, while incident …”
Page 41, Line 1118-1119:
“… and thus the submersion model of this report is a reasonable approximation …”
Not just a reasonable approach, but probably also a conservative approach, which is often required when calculating the radiological doses during plume passage.
Page 41, Lines 1123-1124:
Please refer to Fig. 5.6 here:
“… density and shows an example …” --> “… density and Fig. 5.6 shows an example …”
Or the end of the sentence. “… , as shown in Fig 5.6”
Note: a few words on the decreasing functional behavior would be appreciated here.
Page 42, Lines 1153-1154:
“The incident … ground surface”
Please include the mentioned angle with respect to the horizontal plane to the sketch depicted in Fig. 5.5.
Page 42, Lines 1160-1164:
See comments above for Fig. 5.3 about the construction of the y-axis values.
Page 43, Line 1183:
“Monoenergetic sources photons and electrons …”--> “Monoenergetic source photons and electrons …” (remove the final ‘s’ in sources, or alternatively: Monoenergetic sources of photons and electrons).
Page 43, Lines, 1202-1203:
“The ambient dose equivalent, defined as…” --> ”The ambient dose equivalent, H*(10), defined as…”
Page 44, Lines 1206-1215:
These monitors also detect (high energetic) cosmic radiation, which complicates the calibration.
Page 44, Line 1216:
“and ground deposition densities of ” --> “and ground contamination densities of ”
Deposition relates to contamination from plume passage (fall-out), but ground can also be contaminated due to other reasons, e.g., naturally occurring terrestrial sources, contamination by irrigation with contaminated ground water, etc. See issue 5 in ‘General and major remarks’ under part 1 of this review.
Page 44, Lines 1234-1235:
“… the dose coefficients given in …” --> “… the conversion coefficients given in …”
Since particle fluence is converted to a dose quantity, shouldn’t one use the term ‘conversion coefficient’, conform the ICRP-74 and ICRP-116 publications?
Page 45, Line 1244:
“h*(10))” --> “h*(10)”
Remove one “)”, and of course with a dot on the h.
Page 45, Lines 1246-1247:
“Thus,… dose rate”
Maybe it would be a good idea to explicitly state how to do this, i.e., by the ratio of the two obtained coefficients.
Page 45, Line 1256:
“…normally incidence radiations” --> “normal incidence radiations” or
“normally incident radiations”
Page 46, Line 1274:
“…provide reasonable estimates of effective dose…”
How is reasonable defined here?
6. Determination of dose rate coefficients for monoenergetic particles (step 2)
Page 47, Lines 1303-1305:
“… measured ground deposition levels …” --> “… measured ground contamination levels …”
(since, ground contamination may not only follow from fallout/deposition, see earlier remarks)
“… to a unit deposit of each radionuclide …”
Try to avoid the word deposit (see above, issue 5 in ‘General and major remarks’). In addition, radionuclide-specific calculations are performed in step 3, so what does this exactly mean? We suggest the following:
“… to a unit ground contamination of each monoenergetic source emitter …”
Page 47, Lines 1315-1317:
“… the equivalent dose coefficients are numerically equivalent to their corresponding absorbed dose coefficients.” --> “… the equivalent dose ratecoefficients are numerically equivalent to their corresponding absorbed dose rate coefficients …”
Page 49, Lines 1360-1362:
“The effective dose rates … in Section 4.2”
Please also refer to Sections 4.1 and 3.2
Page 49, Line 1365:
“Electrons were evaluated only for sources …” --> “For monoenergetic electron emission, only sources on the air-ground interface were considered(i.e., primary electrons emitted at depth within the soil are not regarded)”
(Electrons could in principle also refer to secondary electrons, which may be confusing)
Page 50, Lines 1385-1386:
“For most energies and all geometries, the smaller the phantom, the larger the effective dose rate coefficient”
-->
“For most energies and all geometries, the smaller the phantom (the younger the age), the larger the effective dose rate coefficient”
Page 50, Lines 1386-1388:
“Larger differences are observed 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” -->
“The largest differences are observed between the adult phantom and the newborn which amounts to considerably more than 140% for energies lower than 50 keV and contamination on the surface of the ground (Table 6.1 and Fig. 6.2)”
Page 50, Line 1391:
“…at energy of 0.01 MeV …” --> “… at energies around 0.01 MeV …”
Page 50, Line 1392-1395:
“This could be … on the ground surface”.
This could be explained more clearly. The mean free path of photons in air indeed decreases with decreasing photon energy. The average photon (energy) flux incident on a standing ICRP reference phantom – especially of young(er) age - may therefore be larger than that at a height of 1 meter at which the ambient dose rate is determined.
Page 59, Lines 1457-1458, Figure 6.7:
The y-axis title should read …m2 instead of …m3.
Page 59, Lines 1462-1463 and Fig. 6.8 (incl. caption, Lines 1468-1471 on page 60):
It would be helpful to plot the ambient dose rate coefficients as a function of depth (in mfp), so that one can observe the (increasing) level of conservatism (with depth) of this environmental monitoring quantity.
Page 60, Line 1494:
“…is higher than the effective dose for all phantoms considered).”
That is, except for the 10 keV photons.
Page 63, Figure 6.10:
Nothing is explained about this figure with the results for the monoenergetic electron sources distributed uniformly in the atmosphere. For small electron energies the adult phantoms exhibit a larger effective dose coefficient (than those for newborns), whereas the newborn phantoms exhibit a larger coefficient at higher electron energies. This should be mentioned and explained.
And how do these values relate to the skin-equivalent dose multiplied by the tissue weighting factor of 0.01 (as is done for water immersion in Fig. 6.13)?
Page 67, Lines 1551-1559:
The text in para (111) [photons] should be before the text in para (110) [electrons].
Para (110): please give an indication of which organs contribute most at electron energies > 1 MeV.
Also use ‘submersion’ instead of ‘immersion’ on Line 1558.
Para (111) : “For photon exposures, the age-dependency … ”
Note that for monoenergetic electron sources, the doses for the adult phantoms are larger at small energies, as seen from Fig. 6.12 (a similar observation is made in Fig. 6.10 for air submersion). This should be explicitly mentioned.
Page 68, Lines 1563-1565:
That at high energies skin is not the only tissue contributing to effective dose is understood, but what is the explanation for the deviation in the 20-100 keV range?
Page 75, Line 1786:
“..reference adults and …” --> “..reference adult and …” (remove ‘s’ from adult since it is used as an adjective.
Page 75, Line 1789:
“…in addition to immersion in…” --> “… as well as for submersion to …”
Page 75, Line 1791:
“… at energy of 0.01 MeV …” --> “… at energies around 0.01 MeV …”
Page 75, Lines 1790-1792
“As previously… h*(10).”
The (three) indicated age categories actually depend on soil depth.
At soil depths of 2.5 mfp and 4.0 mfp, only the newborn and the 1-year old phantoms have effective dose rate coefficients larger than the ambient dose equivalent rate coefficient and thus not the 5-year old phantom (for 0.01 MeV photons). At soil depths of 0, 0.2, and 1.0 mfp, however, also the 10-year old phantoms have an effective dose rate coefficient larger than the ambient dose equivalent rate coefficient.
Note: also for air submersion, the effective dose rate coefficients for several paediatric phantoms is larger than the ambient dose equivalent rate coefficients, see Table 6.7 for energies of about 0.010 MeV. This should also be mentioned explicitly here.
Page 75, Line 1798-1799:
“… the ratio of ambient dose equivalent to air kerma obtained …” --> “… the ratio of ambient dose equivalent and air kerma obtained …”
Page 75, Lines 1806-1809:
“…at 0.2 mfp depth is about 40-70% of that at 0.0 mean free path…….For 1.0 mfp ……is less than 80% of that on the surface….”
This last is probably meant to be as follows: “80% less than the rate resulting from contamination on the surface”?
Page 75, Line 1809-1814 and Fig. 6.21 on page 77:
“Fig. 6.21 … of field”
This paragraph is too short and needs more elucidation since it deals with a completely new operational quantity. See issue 9 in ‘General and major remarks’ (part 1 of this review).
Furthermore, instead of the plot of Fig. 6.21, it may be helpful to plot the ratio of the ambient dose equivalent rate and the newly proposed ambient dose rate to better visualize the differences (and similarities) between both quantities as a function of photon energy and soil depth.
7. Equivalent and effective dose rate coefficients for radionuclides (step 3)
Page 78, Line 1841:
The right-hand side of equation (71) misses the index N referring to the radionuclide under consideration. The yield Y_R,i and the energy of emission E_i should at least contain the index N.
Page 78, Line 1848:
“… as provided in Section 5” --> “… as provided in Section 6”
Page 78, Lines 1835-1861:
General remark on sections 7.1 and 7.2. It should be explicitly mentioned that the coefficients calculated by equations (7.1) and (7.2) are calculated for the indicated age groups (newborn, 1 year, 5 year, 10 year, 15 year and adult). In other words, and age dependence should be indicated in these equations as well (Note: even though the radionuclide-specific, organ equivalent and effective dose rate coefficients are age dependent, the set of tissue-weighting factors is taken equal for each age group (values of w_T are age- and sex-averaged values)).
Furthermore, we refer to issue 8 raised in the first part of this review (‘General and major remarks’).
In the electronic supplement, are the radionuclide-specific dose coefficients for ground contamination presented at actual physical depths (in cm or g/cm2)?
Page 79, Lines 1880-1884:
Right-hand side of equations (7.3) and (7.4) should include the index N referring to the nuclide under consideration (i.e., photon yield Y_photon,i and energy of emission E_i).
Page 79, Lines 1877-1896:
General remark on section 7.3. For future use, ICRP could also include the radionuclide-specific ambient dose rate coefficients (i.e. for the newly proposed quantity) as described in Section 8.4. See also issue 9 in ‘General and major remarks’ (part 1 of this review).
8. Application of dose rate coefficients
Pages 80-81, Lines 1898-1961:
General remark on Section 8.1: see issues 8 and 10 in the first part of this review.
Pages 89-90, Lines 2002-2061:
See issue 11 in the first part of this review (General and major remarks).
Pages 91-92, Lines 2096-2140:
See issue 9 in the first part of this review (General and major remarks).
Page 92, Line 2128:
“The ambient dose coefficients …”
Note that all coefficients given in this report are dose-rate coefficients. Please indicate that here.
Page 92, Lines 2134-2135:
“where … around epsilon”
d(Phi_i(epsilon))/d(epsilon) is the fluence of particles at that point with kinetic energies in the interval d(epsilon) around epsilon, but per unit of energy! It is the fluence-energy distribution expressed in the unit 1/(cm2.J) or 1/(cm2.MeV). The fluence itself (in the indicated energy domain) is d(Phi_i(epsilon)).
Page 92, Lines 2150-2157:
This paragraph contains a lot of repetition. Please rephrase.
Page 92, Line 2157:
“… the one describes in …” --> “… the one described in …”
9. Conclusions
Page 93, Line 2163:
“… environmental exposure to the public …” --> “… environmental exposure of the public …”
Page 93, Line 2165:
“… submersion in a contaminated …” --> “… submersion to a contaminated …”
Page 93, Line 2170:
“… environmental radionuclides …” --> “… radionuclides in the environment …”
Page 93, Line 2194:
“… from nuclear and radioisotope facilities …”
Also from the processing/NORM industry.
Page 93, Line 2207:
“…of 0.4-0.6 which accounts…”
Please give reference.
Page 94, Line 2208:
“…occupancy factor of 0.6…”
This is very low! UNSCEAR uses 0.8 and in many European countries, it is even above 0.9.
References
Page 99, Lines 2450-2451
This 2016-reference for Satoh should be moved after the 2015-reference (Lines 2455-2457) to maintain chronological order.
Page 99, Lines 2455-2457
Reference Satoh et al, 2015 was published in 2016 (see Google Scholar or Scopus).
Annex B. Skin dosimetry
Page 104, Line 2640:
“… environmental radionuclides …” --> “… radionuclides in the environment …”
Page 104, Line 2659:
Section B.1.1 does not exist.
Page 106, Line 2720:
“… the skin dose rate coefficients …” --> “… the skin equivalent dose rate coefficients …”
Page 106, Line 2723:
“… polygon mesh phantom and the GEANT4 … ” --> “… polygon mesh phantom coupled to the GEANT4 … ”
Page 106, Line 2728:
“… absorbed dose …”
This is true, but since in Figs. B2 and B3 the skin equivalent dose rates are shown, ‘absorbed’ can better be changed to ‘equivalent’.
Page 107, Line 2748:
“ … CSDA range …” --> “ … CSDA (Continuous-Slowing-Down Approximation) range …”
Page 108, Line 2752:
“ … having CSDA range less …” --> “ … having a CSDA range less …”
Annex C. Content of the electronic supplement
Page 114, Lines 2888-2889:
Units are incorrect: nSv h-1 Bq-1 m-2 or nSv h-1 Bq-1 m-3 --> nSv h-1 Bq-1 m2 or nSv h-1 Bq-1 m3