Aircrew and Spacecrew Radiation Exposure “The Dangers of Getting High” B.J. Lewis B.J. Lewis Royal Military College of Canada Royal Military College of Canada Ottawa Chapter, Canadian Nuclear Society Ottawa Chapter, Canadian Nuclear Society Ottawa, Ontario Ottawa, Ontario April 16, 2009 April 16, 2009
Outline � Aircrew Radiation Exposure Assessment � Measurements and Computer Code Development � Space Radiation Monitoring
Typical Annual Radiation Exposure Total Average Annual Exposure 3.6 mSv
Impetus • ICRP-60 (1990) and ICRP-103 (2007): – Reduce radiation exposure limits: • Nuclear Energy Worker (NEW): 50 to 20 mSv/year • Public: 5 to 1 mSv/year – Recognize occupational exposure of aircrew to radiation
Aircrew Radiation Regulation • European Union (Basic Safety Standard Directive, May 2000) • Canada (Transport Canada, Commercial and Business Aviation Advisory Circular, April 2001) – Account for exposure for >1 mSv/y (> 8 km) • Assess exposure • Adjust working schedules (> 6 mSv action level) • Inform workers • Control doses during pregnancy (<1 mSv)
Epidemiological Studies • P. Band et al., B.C. Cancer Foundation (Cdn/AC Pilots, 1950-1992) – Excess AML and prostatic cancer • J. Grayson et al., Brooks AFB (USAF Pilots, 1975-1989) – Excess cancer in all sites, testis & urinary bladder • E. Pukkala et al, Finnish Cancer Registry (FAs, 1967-1992) – Excess female breast and bone cancer • European Study of Cancer Among flying PErsonnel (ESCAPE) (9 countries) (1960-1997) – Scarce evidence for specific occupational cancer risk – Revised interest with ESCAPE II (or COSMIC) study to include US PAN AM cohort • D. Irvine, British Airways Pilots, 1998 • B. Grajewski, NIOSH Studies (FA (1998-2000), Pilots (2001)) – FAs reproductive health effects – Biomarker study of pilots
Radiation Exposure to Aircrew Complex mixed-radiation field Solar Particle Events Galactic Cosmic Rays (GCR) (SPE)
Galactic Cosmic Ray (GCR) Exposure Conditions • Relatively constant field dependent upon: • Solar Activity • Latitude • Altitude • Complicated field • Many particle types, large energy range • Greater uncertainty in biological risk
Solar Magnetic Field Shielding (When) • GCR intensity GCR intensity anticoincident anticoincident with solar cycle with solar cycle 400 4500 350 4000 C lim a x H o u rly C o u n t R a te /1 0 0 300 3500 S u n s p o t N u m b e r 250 200 3000 150 2500 100 2000 50 23 19 20 21 22 0 1500 1953 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003 2008 Year
Earth Magnetic Field Shielding (Where) • Greater shielding at equator than geomagnetic poles (factor of ~3)
Atmospheric Shielding (How High) Satellite 40 km Balloon Atmospheric 20 km Nucleus Supersonic 10 km Subsonic High Peaks 1 km
Equipment Suite Development Detector NIMs, Computers, UPS Anthropomorphic Phantom with TLDs and BDs MNS BGO Scintillators LET Chamber NE213 Scintillator LLRM
Commercial Aircraft Measurement Eberline Eberline TEPC TEPC SWENDI SWENDI NRD NRD Ionization SWENDI Ionization SWENDI Chamber Chamber
Aircrew Radiation Studies � Experimentation • ~250 Flights (Portable Instruments) • Ionization Counter/Al 2 O 3 TLDs (low-LET) • SWENDI Remmeter/Bubble Detectors (high-LET) • Liulin-4N and 4SN (Si-based) LET Spectrometers • Tissue Equivalent Proportional Counter (Hawk TEPC) � Model/Code Development • Predictive Code AIrcrew Radiation Exposure (PCAIRE)
Ambient Dose Equivalent Distribution ( μ Sv) 60 40 20 0 TEPC IC TLD SWENDI BD TOTAL = IONIZING + NEUTRON
Quality Factor Q>1 Q=20 Other Q>1 Q=1 Lung 3% Gamma 1 Gamma 1 62% 38% 4% Ionizing Ionizing X- -Ray Ray X 1 (low- -LET) LET) 1 (low Q=1 93% Electron Electron 1 1 Neutrons Neutrons Aircrew US Atomic Radiation Workers (high- -LET) LET) (high 20 20
TEPC Data from Selected Flight Routes Global Flight Group Flight Total Dose Q Eq. ( μ Sv) Time (h) 2.2 ± 0.4 57 ± 9 10.2 Trans-Pacific (CYVR-KIX) 2.5 ± 0.4 39 ± 6 6.5 Trans-Atlantic (CYYZ-LHR) 2.4 ± 0.4 35 ± 5 5.0 Trans-Canada (CYYZ-CYVR) 2.2 ± 0.4 27 ± 4 5.7 Caribbean (BGI-CYYZ) 3.4 ± 0.6 54 ± 28 10.2 Northwest/Yukon (CYOW-CYFB CYRB-CYSR-CYFB-CYOW)
PGUA Data Coverage DIAP LP PD HNL
TEPC Count Rate 2500 40000 Count Rate (C ounts/M in) 35000 2000 30000 Altitude (ft) 25000 1500 20000 Constant Latitude 1000 15000 10000 500 Heading North 5000 0 0 19:00 20:00 21:00 22:00 23:00 0:00 1:00 2:00 0:00 1:00 2:00 3:00 4:00 5:00 6:00 7:00 Time (Z) Time (Z)
YGK-YYZ-HGK Polar Flight (2005) Toronto to Hong Kong Hong Kong to Toronto 10 12000 IC+SWENDI HAWK FH41B 10000 LiuLin FH41B Corrected Ambient Dose Equivalent Rate (uSv/h) Flight Altitude 8000 Altitude (m) 1 6000 4000 2000 0.1 0 4/18/05 9:00 4/18/05 21:00 4/19/05 9:00 4/19/05 21:00 4/20/05 9:00 4/20/05 21:00 Date and Time YGK-YYZ YYZ-HGK (polar) HGK HGK-YYZ YYZ-YGK
TEPC Data Analysis Geomagnetic latitude calculated from geographic latitude & longitude tude Geomagnetic latitude calculated from geographic latitude & longi 16 Ambient Total Dose Equivalent Rate, H ( μ Sv/h) 9.4 km 10.0 km (+2 μ Sv/h) 14 10.6 km (+4 μ Sv/h) . 11.2 km (+6 μ Sv/h) 12 11.8 km (+8 μ Sv/h) Best Fit at 10.6 km 10 8 6 4 2 0 -45 -30 -15 0 15 30 45 60 75 90 Geomagnetic Latitude, B m (deg)
Latitude Dependence: Dose Rate Vs Cutoff Rigidity GCR ability to penetrate magnetic GCR ability to penetrate magnetic Ambient dose equivalent rate (35000 ft) field field Ambient Dose Equivalent Rate ( μ Sv/h) 10 North South 8 Best Fit 6 Global Cutoff . Rigidity 4 Contours 2 0 0 2 4 6 8 10 12 14 16 18 Cutoff Rigidity, Rc (GV)
Altitude Effect (Balloon Flights) Balloon Data (July 14, 2001) Satellite Balloon Data (July 23, 2001) 40 km 10 M odel Balloon Atmospheric 20 km 1 Nucleus Supersonic f Alt 10 km Subsonic 0.1 High Peaks 1 km 0.01 0 200 400 600 800 1000 2 ) Atm ospheric Depth h (g / cm
Solar Cycle Effect (10.7 km) 8 Ambient dose equivalent rate ( μ Sv/h) RMC IC+SWENDI (Climax = 3744 counts/h/100, Φ = 984 MV) ACREM IC+NMX (Climax = 4277 counts/h/100, Φ = 498 MV) Best Fit ACREM IC+NMX 6 Best Fit RMC IC+SWENDI normalized to 10.6 km 4 2 IC + SWENDI 0 0 2 4 6 8 10 12 14 16 18 Vertical cutoff rigidity R c (MV) Equator Poles
PCAIRE Code Visual_PCAIRE.exe
PCAIRE Code vs Concorde/ER-2 (NASA) (High-Altitude) 160 ER-2 North 1 Heliocentric Potential (FAA) TEPC Measured Route Dose (uSv) 140 Deceleration Param eter (NASA) 120 ER-2 North 2 100 ER-2 East 80 60 ER-2 South 1 & 2 40 15.2 -18 km (Concorde) Concorde Flights 20 15.2 - 21 km (ER-2) 0 0 20 40 60 80 100 120 140 160 PCAIRE Predicted Route Dose ( μ Sv)
Aircrew Annual Exposure Flight Attendants Pilots ICRP 60 Public Limit 6 5 4 3 2 1 0 Dose Equivalent (mSv) PC-AIRE Prediction of Annual
Canadian Annual Occupational Exposures 99-EHD-239 6 Nuclear Fuel Handler Average Exposure Industrial (mSv/year) Radiographer 4 Uranium Miner Nuclear Medicine 2 Technologist Commercial Aircrew 0 Occupation
Health Impact • ~25% of population will develop fatal cancer • If aircrew exposed to 6 mSv/y over 30 years, risk of developing a fatal cancer: 6 mSv/y x 30 y x 4 x10 -5 cancers/mSv = 0.7%
Radiation Exposure from Solar Particle Events (SPE) • Highly sporadic events associated with solar flares and coronal mass ejection – Additional exposure to aircrew
Aircrew Exposure from SPEs • Propagate GCR and GOES-11 spectra (p, He) through atmosphere with Monte Carlo Code (MCNPX) Proton Flux (n/MeV/sr/cm 2 ) SPE GCR Proton energy (MeV)
Dose and NM Count Rate Prediction Primary GOES Dose Conversion Dose Rate spectrum Coefficient ⎡ ⎤ ⎧ ⎫ m n ⎛ ⎞ m 3600 s ( ) ( ) ∑ ∑ ∑ & & & & − = ⋅ Δ ⋅ ⋅ ⋅ prim = prim H c E K P ⎜ ⎟ Φ P E Φ E 1 ⎨ ⎬ ⎢ ⎥ E , ( Sv h ) + Ω Ω i i j ij E A i E i , 1 , i , ⎝ ⎠ ⎩ ⎭ ⎣ h ⎦ = = = i j i 1 1 1 ⎡ ⎤ ⎧ ⎫ m n ⎛ s ⎞ m ( ) ( ) ∑ ∑ 3600 ∑ & − & prim & prim = ⋅ Δ ⋅ ⋅ ⋅ = ⎜ ⎟ C c E R P Φ P E Φ E 1 ⎨ ⎬ ⎢ ⎥ ( count h ) + Ω Ω i i j ij E NM i E i , 1 , , ⎝ h ⎠ i ⎩ ⎭ ⎣ ⎦ = = = i j i 1 1 1 MCNPX matrix coefficients NM Count Rate Energy bin width NM Response Function Noisy Sun Effects Global Cut- off Rigidity Contours
Solar Storm Effects and Solar Flare Anisotropy "SOHO (ESA & NASA)"
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