Information session on aircrew exposure to cosmic radiation – Brussels – 20/01/2009
S. Pepin (Federal Agency for Nuclear Control)
Belgian regulations with respect to cosmic rays exposure and results of the dose assessment
What is cosmic radiation ? Primary cosmic radiation: high energetic particles from space (mainly hydrogen and helium nuclei)
Galactic component (main component): e.g. supernova explosions,…
Solary component (11-years cycle, may be significant in case of solar disturbance event / solar flare – e.g. 1956)
What is cosmic radiation ?
Secondary cosmic radiation - interaction of primary cosmic radiation with earth’s atmosphere => secondary particles
2 main factors affecting the flux of cosmic radiation:
- Altitude (absorption by the atmosphere)
- Latitude (protection due to earth’s magnetic field decreases with latitude – highest dose near the poles)
European regulatory framework (1)
European Directive 96/29/EURATOM
If dose > 1 mSv/y, airlines shall:
• assess the exposure of the crew concerned • take into account exposure when organizing working
schedules with a view to reducing the doses of highly exposed aircrew.
• inform the concerned workers about the health risks their work involves.
• take care of limitation of doses during pregnancy (< 1 mSv/y + ALARA - “As Low As Reasonably Achievable”).
European regulatory framework (2)
Radiation protection 88: “Recommendations for the implementation of Title VII of the European Basic Safety Standards Directive concerning significant increase in exposure
due to natural radiation sources”
- “Highly exposed aircrew” : > 6 mSv/y- 1 – 6 mSv/y: individual estimates of the dose- > 6 mSv/y: appropriate medical surveillance
Belgian regulatory framework (1)
Euratom directive => Royal Decree of 07/20/2001 (article 4 and 9)
Art. 9 : For aircrew with dose possibly > 1mSv/y:• assess individual doses • take into account dose assessments in the working schedules
(at least < 6 mSv/y)• inform the concerned workers (+ company medical officer)• limitation of doses during pregnancy (As Low As Reasonably
Achievable – in any case < 1 mSv/y)
NB: till now, no specific medical follow-up if dose < 6 mSv/y
Belgian regulatory framework (2)
- Guidelines from the FANC(http://www.fanc.be => folder “Natural radiation”) - “Exemption criteria” (e.g. altitude < 6000m +
flying time < 700 h)
- If no exemption software-based evaluation
- Yearly dose evaluation if dose > 1 mSv/y- Monthly if dose > 6 mSv/y
Results of dose assessment 9 commercial airlines investigated.
Last december, information campaign for non-commercial airlines
Commercial airlines:- 3 “exempted” (“air taxi” companies)- 6 with doses > 1 mSv/y
Software used: CARI, IASON-FREE, PCAIRE, GlobaLog
Dose assessment for 1429 persons
907 people > 1 mSv/y (average dose ~ 2 mSv/y)Nobody > 6 mSv/y
Maximal dose = 4 mSv/y
Dose distribution (1)
Company A (IASON), Company B (PCAIRE) – charters flight
Company A
0
10
20
30
40
50
60
70
80
90
1 - 1,5 mSv
1,5 - 2 mSv
2 - 2,5 mSv
2,5 - 3 mSv
Company B
0
20
40
60
80
100
1 - 1,5 mSv
1,5 - 2 mSv
2 - 2,5 mSv
2,5 - 3 mSv
3 - 3,5 mSv
3,5 - 4 mSv
Distribution pattern depends on specific airline (flight profile,…)
Dose distribution (2)
Global dose distribution for all companies
All companies
1,5 - 2
2 - 2,5
2,5 - 3
3,5 - 4
1 - 1,5
3 - 3,5
0
50
100
150
200
250
Dose (mSv)
Nu
mb
er o
f p
erso
ns
Significant # people in the upper range of the distribution
Conclusions - Majority of aircrew members > 1 mSv/y- Dose distribution pattern depends on specific airline
Open issues :- Parameters affecting the dose distribution ? - Which optimisation measures ? - Necessity and type of medical follow-up for dose 1 – 6 mSv/y ?
