Air Crew Hazards and Safety: FAA Uses of Neutron Monitor Data in Aviation

Radiation Safety

Presented by Kyle A. Copeland, Ph.D.

2015 Neutron Monitor Community Workshop

24-25 October 2015

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http://www.faa.gov/data_research/research/med_humanfacs/aeromedical/radiobiology/

E-mail: Kyle.Copeland@faa.gov

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Ten highest average annual effective doses among monitored workers worldwide (1990-

1994) [UNSCEAR, 2000].

Practice Rank Effective dose / mSv . y-1 Above-ground radon from oil and natural gas extraction

1 4.8

Nuclear fuel mining 2 4.5 Nuclear fuel milling 3 3.3 Aircrew 4 3.0 Mining other than nuclear fuel or coal 5 2.7 Radioisotope production 6 1.93 Industrial radiography 7 1.58 Nuclear fuel reprocessing 8 1.5 Reactor operation 9 1.4 Nuclear fuel fabrication 10 1.03

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The annual dose for aircrew will increase as the average flight altitude increases! In 2012 there were about 200,000 US crewmembers (U.S. BLS).

Ionizing Radiation in Aviation

<0.13 mSv

<30 mSv per event, rare

<6 mSv, primary source

<10 mSv per event, rare

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Stochastic and Deterministic Effects

Increased lifetime risk* Stochastic Effect Whole population Age group 18-64 years Genetic defect in first or second generation (child or grandchild) following irradiation before conception 0.4 in 100,000 per mSv 2.4 in 1,000,000 per mSv

Cancer (non-fatal or fatal) 34 in 100,000 per mSv 23 in 100,000 per mSv

Cancer (fatal only) 8.0 in 100,000 per mSv 6.3 in 100,000 per mSv*Risks assumes exposure to high-LET radiation (i.e., no DDREF) [ICRP Pub. 103]

Deterministic Effect Threshold Dose None Significant <0.1 GyRisks to conceptus (mental retardation, malformation, etc.) 0.1-0.5 GyTransient mild nausea and headache in adults 0.35 Gy

Effective Dose Limits for WorkersPregnant 1 mSv for duration of pregnancy and 0.5 mSv per monthOther 100 mSv per 5 years and no more than 50 mSv in any one year

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1. The heliosphere

2. Solar wind

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Galactic Cosmic Radiation:How does it get here?

Source: NASA

Shea and Smart, 2001

Earth’s Atmosphere

For aviation, the practical boundary of the atmosphere is 100 km (328,000 ft)

78% nitrogen

21% oxygen

0.93% argon

0.034% (average) carbon dioxide

trace amounts of other gases

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88

Galactic Cosmic Radiation Levels, January 1958 through December 2008

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http://notrickszone.com/2012/12/05/brutal-cold-headed-for-europe-and-north-america-solar-and-ocean-cycles-bode-of-an-approaching-little-ice-age/#sthash.GG7K40fN.dpbs

Per

cent

, %

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Solar Dose RatesDuring an SPE, cosmic ray spectrum modelling is more complex. - The particle spectra are constantly

changing.

- GOES satellite instruments provide good data for protons up to about 1 GV, but not higher energies.

- Isotropy of incident cosmic ray flux is often a poor assumption, particular at the start of events when fluxes are usually highest.

- To provide a good picture of anisotropy, a world grid of neutron monitors is needed. Data from many monitors is needed to maximize accuracy of post-event assessments.

http://www.dtic.mil/dtic/tr/fulltext/u2/a235394.pdf (Smart and Shea, 1990)

http://neutronm.bartol.udel.edu/listen/main.html#tell

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Summary: Why Neutron Monitors Matter

Galactic Cosmic Radiation - NMs are used for observing solar modulation in real time.- High resolution (hourly) data covers practically the entire jet age of civilian flight (starting in the late 1950s). - Useful for both long-term monitoring (solar cycle) and short-term variations (Forbush

effects).- One monitor is enough, if statistics are really good.

Solar Cosmic Radiation- Need multiple monitors at different altitudes and geomagnetic latitudes, both N and S.- NM data, along with GOES data, are the basis for calculation of SPE intensities. - Provide the best data for anisotropy calculations needed to drive more sophisticated SPE

flight dose models.- Provide the best insight into multi-GeV proton and alpha spectra during a SPE, satellite

instruments do not have enough shielding to discriminate well.

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