Assessment of Radiation Exposure of Astronauts in Space

Draft document: Assessment of Radiation Exposure of Astronauts in Space
Submitted by Binquan Zhang, National Space Science Center, CAS, China
Commenting as an individual

Dear Dr. Clement, Dr. Sasaki and authors,

   Thank all of you for the great efforts in preparing this valuable publication. I am working at the National Space Science Center, China. This publication provides us a lot of information and will be very helpful for my job. Personally, I have some comments and queries as follow:

 (1) Page 1

Line 27, ‘J. Xianghong’ shoud be ‘X. Jia’. ‘Xianghong’ is Dr. Jia’s first name.

 (2) Page 4:

line 130, ‘J. Xianghong’ should be ‘X. Jia’.

Line 133, ‘Z. Yongzeng’ should be ‘Y. Zhou’.

Line 135, ‘Jinzeng Ma’ should be ‘J. Ma’ or ‘Jizeng Ma’. ‘Jizeng’ is Dr. Ma’s first name.

 Line 113~114, sentence ‘Space flight is one of the occupational exposures from natural souces already listed in ICRP Publication 60 (1991),’ seems to be inconsistent with the sentence in Page 6, line 197~199 ‘Therefore, although astronauts are exposed to ionizing radiation during their occupational activities they are usually not classified as being occupationally exposed in the sense of the ICRP system for radiation protection’.

 (3) Page 5:

 Line 146~147: ‘Depending on the time present in space, mission doses to astronauts may become much higher than 100 mSv.’

  Comments: It’s true that if the astronauts stay longer in space, the doses may be higher. The question is how long it will take to get the doses higher than 100 mSv. Would you please specify the duration time to achieve this dose?

 Line 149, ‘Due to the specifics of the radiation field in space’, add comma ‘,’.

 Line 163, add comma between ‘the primary radiation fields’ and ‘transport calculations’.


(4) Page 6:

  Line 192, ‘ plans are already discussed…’ might be ‘plans have already been discussed…’

  Line 200, ‘7 chapters’ might be ‘seven chapters’.


(5) Page 7:

Line 239, ‘equivalent s’ might be ‘equivalents’.

Line 240, ‘Z=58’ might be ‘Z=28’ according to Page 105, item number (275). Please have a check.


(6) Page 9:

  Line 301, there is a display error for H’(d,Ω).

Line 315, add ‘for the specific radiation’ after ‘the quality factor’.


(7) Page 13:

Line 504, in the publication, both DL and D(L) (page 63,line 2091) are used to represent the absorbed dose distribution in L. For consistency, I would prefer to replace all ‘DL‘ with ‘D(L)’ in the publication.


Line 510~511, in the definition of ‘Magnetosphere’, Radiation belt is not well defined. Would you please describe/define the belt?


(8) Comments on the ‘GLOSSARY’ part:

a) It might be better to use ‘The SI unit of ….’ Instead of ‘The unit of ….’ When give the unit for each glossary.


b) If it has already been defined in previous ICRP publication such as ICRP 103, the glossary in the publication should be exactly the same to avoid any confusion.


(9) Page 17:

Line 636~637, ‘In manned space flight astronauts may experience three different exposure conditions.’ However, in the following text of this paragraph, it seems that just only two conditions (LEO and interplanetary) are described.


Line 651~652, sentence ‘They are living under extraordinarily different environmental conditions than ever encountered on Earth.’ might be changed to ‘They are living under extraordinarily different environmental conditions which they never encountered on Earth.


(10) Page 21,

Line 783,  ‘solar Roentgen flares’ might be ‘solar x-ray flares’.

 Item (14), ‘From the point of view of radiological protection, the focus is on the particulate components of space radiation of ions and electrons only.’  I think neutron is also an important component for space radiation protection as it contribute 10%~30% to the dose of astronauts.


(11) Page 24

Line 886~887, ‘Figure 2.2 shows the abundances of these elements up to tin….’. The charge number of Tin is 50. However, figure 2.2, only shows abundances of elements with the charge number not more than 27. It seems that ‘tin’ should be changed to ‘iron’.


(12) Page 25

Line 910, ‘Fluence rate distributions in energy for hydrogen, helium, carbon and oxygen, and iron are shown in Fig. 2.3.’ However, in Fig. 2.3 there is no distribution for carbon.


About the Fig. 2.3, there is a rectangle with grey lines which should be deleted.


Line 928~929, ‘Cosmic particles incident on the solar system interact with the solar magnetic field and thus lose energy. This leads to flattened energy spectra at lower energies.’

This description might not be correct. Cosmic particles do not lose energy during the interaction with magnetic field.  From NCRP Report 2000, the modulations of cosmic particles are attributed to three main processes: diffusion; convection by the solar wind; adiabatic deceleration.


(13) Page 27

Line 983, “ground –level events” (GLE). However, in page 984, line 1015, ‘GLE’ is also used as the abbreviation of ‘Ground level enhancement’.

 Line 987, ‘the present solar cycle’ might be changed to ‘the solar cycle 22’.

 Line 1001, ‘Such events can induce …..’, please replace ‘Such events’ with ‘The SPE’.


(14) Page 28,

Line 1011~1012, ‘For a sixth event – that of February 23rd 1956 – the fluence distribution…’, I am sorry that I don’t really know why call the event ‘a sixth event’. Is it the sixth event in 1956 or in that solar cycle or other?


Line 1030, ‘A small fluence rate of solar particle with low energies also reaches the Earth…’, Would you specify the value of ‘low energies’?


(15) Page 29,

Fig. 2.7., it seems that the tag for each line is not correctly showed. Same errors are also seen in Fig. 2.9, Fig.3.8, Fig.4.4, Fig.4.6 and Fig.5.10.


(16) Page 30,

Line 1077, ‘A major application which these models…’, would you please list any other models besides AP-8? Or else, I would like to replace ‘which these models have been designed for’ with ‘of the AP-8 model’.

 Line 1095, ‘34 MeV’ might be ‘4 MeV’ as seen in Fig. 2.8.


(17) Page 33,

Comments on Item (47): The albedo neutrons contribute to radiation field in LEO is low, while contribution of neutrons from the interactions of GCR with spacecraft is substantial. In this item, I think, more description such should be given to the latter neutrons.



(18) Page 34,

Line 1181, please replace ‘a charge particle’ with ‘ a charge particle from GCR or SCR’.


(19) Page 37£¬

Line 1247, ‘Figure 14’ should be ‘Figure 2.14’.



(20) Page 43,

Line 1431~1432, ‘For its definition the terms “expanded” and “aligned” radiation field are introduced (see Glossary)…’. However, in the Glossary, these two radiation fields have not been described or defined.

 Item (77), ‘For area monitoring the quantity for assessing the dose to the skin and the extremities (hands, arms, feet) and the dose to the lens of the eye, the operational quantity is the directional dose equivalent, H'(d,Ω) defined by:’

Please rewrite as:

‘For area monitoring, the operational quantity for assessing the dose to the skin, the extremities (hands, arms, feet) and the lens of the eye, is the directional dose equivalent, H'(d,Ω) defined by:’.


(21) Page 44,

Line 1494, please replace ‘has already been’ with ‘was’.


(22) Page 45,

Line 1529, ‘by different types end energies’ might be ‘by different types and energies’.


(23) Page 51,

Line 1659, ‘Except for neutrons, all types of particles are given a single weighting factor value.’ This sentence might be rewritten as ‘A single weighting factor value is given for each type of particle except neutron.


(24) Page 53,

Line 1732, ‘Differences between QT for a single organ and wR may be, ….’ is better to written as ‘Differences between QT and wR for a single organ may be, …’.


 (25) page 67,

Table 4.2., the ‘TL –system (PILLE)’ belongs to passive detector, although the data could be read on board.


 (26) Page 70,

              Line 2309~2310, ‘However, those instruments are not suitable for use in spacecraft because of their heavy weight as well as their high sensitivity to HZE particles.’

              In this sentence, ‘those instruments’, which are bonner spheres if I am right, are not suitable.  But the following sentence tells us that Bonner Ball Neutron Detector (BBND), which is also made of bonner spheres, was used on space Shuttle flight and on ISS. It seems that these two sentences are inconsistent. Personally, I prefer to delete the sentence ‘However, those instruments are not suitable for use in spacecraft because of their heavy weight as well as their high sensitivity to HZE particles.’


(27) Page 78,

Line 2638~2639, ‘national standards (NMI) or related to NMIs…’.

NMI is not the abbreviation of ‘national standards’. It seems that ‘NMI’ is the abbreviation of ‘National Measurement Institute’ of Australian, which is not an international standard. So, I prefer to rewrite this as ‘national standards or related to national standards….’.


(28) Page 79,

Line 2672, the WELMEC software guide 7.2 is a European software guide and it might not be accepted by other countries. As this is an ICRP publication, its recommendations will be and could be adopted internationally. So, it’s better to delete or rewrite the sentence ‘Dosimetry system software should be guided by the WELMEC software guide 7.2 (WELMEC,2008)’.


(29) Page 81,

Line 2772, ‘high-energy and charge (HZE)’

In this publication, HZE are used as the abbreviations of ‘high-energy and charge’(Page 81),‘high-LET heavy charged particles’(Page 71), ‘high charge and energy’(Page 90), ‘high charge, and charge number Z>2 and high energy’(Page 24).

They have almost the same meaning, but for consistency in this publication, please use HZE as the abbreviation of ‘high charge and energy’. 

(30) Page 90,

Line 3081, line 3089, there is a display error for particles ‘π+-+-.’ 

(31) Page 95,

Fig. 5.6, please specify the figures (a), (b) and (c) for liquid hydrogen, water and aluminum, respectively.


32) Page 108,

Fig. 6.6., under the title of x-coordinate, there is a redundant grey line which could be seen when zoom in the page to 300% or print the page out. Same problems could be found in Fig. 6.7, Fig. 6.11 and Fig. 6.4.