Ionising Radiation

Ionising RadiationParticles and electromagnetic radiation released by the decay of unstable atoms

Ionising RadiationAlpha particlesBeta particlesNeutronsGamma raysX rays

Ionising RadiationAlpha particlesBeta particlesNeutronsGamma raysX rays

Radionuclides

Ionising RadiationAlpha particlesBeta particlesNeutronsGamma raysX rays

Elecromagneticradiation

Non - Ionisng Ionising

Half - life

The time taken for the activity of a radionuclide to decay by half its value

Half - life

Isotope Half-Life

Tritium 12.4 yCarbon 14 5730 ySulphur 35 87.4 dPhosphorus 33 25.6 dPhosphorus 32 14.3 dIodine 125 60.1 d

What is radiation used for?

Power generation

Laboratories

Radioactive tracers

Medical

Thickness gauges

Units

Activity (Becquerel)

1 Becquerel = 1 disintegration per second

Absorbed Dose (gray)

1 gray (Gy) = energy absorption of 1 joule/Kg

Dose Equivalent (sievert)

Equivalent dose (Sv) = Absorbed dose (Gy) x Q

Dose Equivalent (sievert)

Equivalent dose (Sv) = Absorbed dose (Gy) x Q

Q is "quality factor“, dependent upon radiation type

Q

Photons, all energies 1

Electrons and muons, all energies 1

Protons 2

Alpha particles and other atomic nuclei 20

Effective Dose

Effective dose = Equivalent dose (Sv) x N

Effective Dose

Effective dose = Equivalent dose (Sv) x N

N is weighting factor dependent upon tissue type

N

Bone marrow, colon, lung, breast, stomach

0.12

Gonads 0.08

Bladder, brain, salivary glands, kidney, liver, muscles, oesophagus, pancreas, small intestine, spleen, thyroid, uterus

0.05

Bone surface, skin 0.01

Dose Employees(age 18+)

Trainees(age <18)

Members of Public

Effective dose 20 mSv 6 mSv 1 mSv

Equivalent dose for eye 150 mSv 50 mSv 15 mSv

Equivalent dose for skin 500 mSv 150 mSv 50 mSv

Equivalent dose for the hands, forearms, feet and ankles 500 mSv 150 mSv 50 mSv

Annual dose limits for employees and members of the public

Regulation 11 of Ionising Radiations Regulations 1999

Geiger Counter

Effects

Alpha particles

Stopped by sheet of paper or skin

Beta particles

Stopped by few mm of aluminium

Gamma rays

Stopped by several metres of concrete or cms of lead

Short term effectsCellular damageRadiation sickness

CancerGenetic damageReproductive effects

Long term effects

Internal HazardsExposure to radioactive particles by :inhalationingestionskin absorption / penetration

Radiological risk Dose (µSv) Risk of Death

Living in CornwallBrain scan

Average annualRadon

Transatlantic flightChernobylChest X-ray

135 g brazil nuts

7800500027001000

69462010

1 in 3,2001 in 5,000

1 in 10,0001 in 25,0001 in 35,000

1 in 500,0001 in 1.25 million1 in 2.5 million

Source: Health Protection Agency

Radiological Protection

Containment

Shielding

Distance

Distance Dose rate (uSv/hr)

1 metre 1

2 metres 0.25

4 metres 0.06

Restrict exposure duration and frequency

Photo creditswww.chemistryexplained.com/images/chfa_04_img0782.jpgwww.bbc.co.uk/schools/gcsebitesize/science/images/ph_radio10.gifwww.flickr.com/photos/redfiremg/3952257530/sizes/z/in/photostream/http://kilby.sac.on.ca/physics/sph3u/1a-Nuclear/NonMedicalUses/

nonmedicaluses.htmStock.XCHNG (www.sxc.hu)www.OHTA.net

http://www.slideshare.net/mikeslater

occhygiene@btconnect.com

http://diamondenv.wordpress.com

Twitter @diamondenv

Mike Slater

Mike Slater, Diamond Environmental Ltd. (occhygiene@btconnect.com)

This presentation is distributed under the Creative CommonsAttribution-NonCommercial-ShareAlike

UK:International Licence