Assessment of Radiation Exposure of Astronauts in Space

Draft document: Assessment of Radiation Exposure of Astronauts in Space
Submitted by J Eakins, Health Protection Agency
Commenting as an individual

Overall, a useful and comprehensive document on space dosimetry, which will be of significant benefit to researchers working in the field.

Page/Paragraph Specific Comments:

P11, L419             Energy cutoff inherent in definition of LET should be mentioned.

P12, L420             Not clear. LEO definition needs attention/rewriting

P17, (1)                 Here and several other occurrences throughout report: LET is defined [ICRU Report 85] for charged particles only... it is incorrect to refer to it in relation to neutrons or photons.

P21, (15)              Value of 20 g/cm2 quoted must be justified, explained and referenced.

P24, (23)              Cobalt not tin.

P26, (30)              Not clear / needs attention.

P29, Fig 2.7          Not clear

P30, (42)              Value of 1.4 g/cm2 quoted must be justified, explained and referenced.

P40, (61)              “Quotient” interpretation of infinitesimal differentials as simple divisions is mathematically wrong.

P44, (79)              Angle dependence should be included in definition

P45, (85, 86)       Again, here and several other occurrences throughout report, LET is defined [ICRU Report 85] for charged particles only... it should not be used in relation to neutrons or photons.


P55, (111)-(115)                This section needs to be expanded significantly, and put into a solid scientific context. Variables need to be defined properly, and equations need to be justified/derived. More explanation is required in general.
Far more references are needed here too: as it stands, this section appears to be based just on the results of a very limited number of individuals.


P64, (152-180)   This section reads like a review article. Very interesting, but an (already long…) ICRP document is possibly not the most appropriate place for it?

P72, Fig. 4.4        Not clear

P74, Fig. 4.6        Not clear


P81 to 87              Although an interesting review, this section condenses a great deal of nuclear theory into just a few pages, and as such it is not obvious what it really achieves: it contains too much information to be followed by the ‘casual’ worker in the field, and too little to be of use to those needing to apply the theory (code developers, say). In places, it also perhaps seems to refer too much to the work of one of the authors.

P87, (221)            Should be ‘parton’

P87 to P90           Aside from being too brief a synopsis of each Monte Carlo code to be of significant practical use, this section on Monte Carlo programmes could quickly become out-of-date as computer codes tend to develop rapidly. Indeed the MCNP subsection, for instance, fails to mention the recently implemented LAQGSM module; perhaps the descriptions of some of the other codes are also omitting important features? Perhaps this section should either be expanded, with the stated caveat that it is only to be viewed as correct at the time of writing, or else reduced to just a short statement naming available computer codes.

P91         MCNPX data not included in figure.

P95, (245)            The expected result, but not really shown in fig 5.6… graphs (b) and (c) are actually quite similar.

P102, (265 – 268)              An interesting review of phantom use, but perhaps this section could focus more on recommending what should be used now and in the future, rather than what has been used historically?

P103, (269)          Conversion coefficients normally assume secondary particle equilibrium, which may not always be the case in space dosimetry. A discussion on this is needed.

P112, (291)          Quantitative comparison between GCR and trapped proton dose rates not really supported by Table 6.2