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Submitted by Rick Tanner and Neil McColl, Public Health England
   Commenting on behalf of the organisation
Document Radiological Protection from Cosmic Radiation in Aviation
 


GENERAL COMMENTS


We note that this report defines cosmic ray exposures during flight as existing exposures. Whilst ICRP 103 does not state whether exposures of air crew are planned or existing exposures, Table 4 of that Publication indicates that these occupational exposures are not included within existing exposures. We recognize that ICRP may not have intended that interpretation, but it has resulted in conflicting Basic Safety Standards: IAEA state that the “exposure of aircrew to cosmic radiation is considered under existing exposure situations”, whilst EURATOM state that “The exposure of air crew to cosmic radiation should be managed as a planned exposure situation”. EU states are obligated to implement the EURATOM BSS and hence all EU states will end up with legislation that would seem to conflict with this Publication.


In the footnote on page 24 there is a reference to the ICRP revising the Glossary from ICRP 103. It is to be hoped that the revisions are published before this Publication, since that will reduce confusion. There are some differences between the Glossary of this Publication and that already published in ICRP 103, that are hard to reconcile: it is not clear whether they are general changes to ICRP thinking or changes made for this report.


The scope of the publication should be defined. Is it dealing only with scheduled aviation flights? Are business jets and military flights outside the scope?


Lines 563-566. These lines seek to characterise the marginal magnitude of SEP exposures of aircraft crew in relation to the crew’s lifetime exposure. The arguments do not seem solid enough. It is recognised in the report that this group (aircraft workers) is “one of the most exposed” of occupations: that does not make the denominator of lifetime exposure an immediately obvious comparator for assessing something as being marginal. Comparing something large with something larger does not make the first thing small.


Paragraph 20. The quoted evidence is reported in terms of dose rates exceeded at different flying altitudes but without saying how much they are exceeded by or for how long. Thus, the draft report does not illustrate what individual doses might be, while being content to describe them as marginal. The presented evidence and arguments do not link clearly enough to the conclusion of marginality.


DETAILED COMMENTS


Lines 206 and 216 – spurious space before “For”.


Line 211. Change “comparable to” to “comparable to or exceed” (to account for business jets).


Line 246. Spurious “the”: “Cosmic radiation is ionising radiation…”


Line 274. Delete “to occur”


Lines 281-287. This definition of Existing Exposure is much more complex than in ICRP 103. Is this consistent with the revised glossary from that publication?


Lines 300-302. This definition of fluence is wrong: the number of particles incident on a sphere of cross sectional area a is divided by a. The definition should be taken from ICRU Report 85.


Line 322. Remove “generally”.


Lines 324-329. This definition of Occupational Exposure is changed from that in ICRP 103. Is this consistent with the revised glossary from that publication?


Lines 341-344. This definition of Planned Exposure is changed from that in ICRP 103. Is this consistent with the revised glossary from that publication?


Lines 371-373. In the space weather community, SEP, “solar energetic particle”, is a more common term.


Line 374. “Sun’s” is redundant. “Solar Wind” is sufficient.


Line 383. “police control”? Do you mean “passport control”?


Lines 402-404. Whilst ICRP 39 does describe cosmic radiation exposures as “existing”, it uses that term in the context of “existing” and “new”, not “existing” and “planned”. It also only considers dose rates at sea level. So it is not helpful to apply it to air crew dosimetry.


Line 427. Replace “The” with “This”.


Line 486. The lower energy limit is effectively redundant – delete “from 106 electron volts”


Line 509. It is worth stating that the GCR is lower not because of the sunpots, flares and coronal mass ejections. It is lower because of the stronger solar wind.


Line 544. The Bramlitt reference is 2015 not 2014.


Figure 4. Something weird has happened to the labels on the y-axis.


Line 575. Replace both “and”s with a comma.


Line 576. Not sure what is meant by “element”.


Line 600. Aircraft is self-plural. No need for the “s”.


Line 605. ISO 20785 parts 1 to 3 need to all be included in the references. Part 1 is a 2011 reference, and Part 2 2012. But Part 3 was last circulated as a Draft International Standard, so it is not really referenceable yet.


Line 614. “properly” is not a precise enough word.


Lines 658-660 & Figure 7. The air crew distribution does not look like a combination of two Gaussians?


Line 739. The draft report appears to quote text from ICRP-103 that is different from the relevant ICRP-103 extract that is currently available on the ICRP website. If ICRP is still in the process of refining some of the terminology while the current Publication is being prepared, this document should either use the ICRP103 text  “as is” (if that is appropriate) or state clearly that a working definition is used locally that aims to reflect the intentions of ICRP, as the authors understand them.


Paragraph 40. The publication should reference works that have estimated single-flight doses of 20 mSv for a 1 in 100-200 year event. And perhaps works that indicate that the 1 in 1000 year event could be ten times larger.


Line 780. Replace “ones” with “exposures”.


Line 795. Populations needs to be plural.


Lines 795 and 796. This is somewhat understating the case. It is only one of the highest occupational dose occupations in terms of mean dose, but overwhelmingly the highest in terms of collective dose – 70-80% of all recorded occupational dose.


Paragraph 54. This needs to reflect that airlines operate “rerostering” to cope with the reference levels, where long haul crew are switched to lower dose routes, especially short haul. This is distinct from changes to flight paths or limiting flying time.


Line 893. Again, lose the “s” on aircrafts.


Line 931. More codes should be explicitly named.


Line 934. Again, lose the “s” on aircrafts.


Line 960. Change “airlines management inform” to “airline management informs”?


Line 964. Replace “like” with “as”.


Line 1009. Replace “have to” with “should”.


Lines 1046-1049. Better to make this positive? “It is the Commission’s intent to suggest that cosmic radiation be viewed in proportion with other risks or considerations, to foster a more inclusive view of all risks so that individuals can make informed decisions.”


Line 1069. Delete “a” - “provide sufficient shielding”.


Line 1073-1074. “one of” is redundant. Air crew are overwhelmingly the most exposed occupational group.


Lines 1092-1094. As mentioned above, rerostering is current practice – switching to lower dose routes.


APPENDIX A. Title has a missing space – “WITHSELECTED”