Italian Teachers Programme – September 2016

Radiation and radioactivity (around us) Marco Silari

Radiation Protection Group

Occupational Health & Safety and Environmental Protection Unit

[email protected]

M. Silari – Radiation and radioactivity – 6 September 2016 1 Why do you have sheep on the CERN site?

M. Silari – Radiation and radioactivity – 6 September 2016 2 The wrong answer…

The sheep are there to check radioactivity in the grass…

Of course NOT!

M. Silari – Radiation and radioactivity – 6 September 2016 3 CERN has a an extensive environmental monitoring plan

(which does not involve the use of sheep…) Other environ- Stray radiation Air Water mental samples

M. Silari – Radiation and radioactivity – 6 September 2016 4 If I say “radiation” or “radioactivity”, what comes to your mind?

M. Silari – Radiation and radioactivity – 6 September 2016 5 I would guess this? Hiroshima, Japan, 6 August 1945

Chernobyl, Ucraine, 26 April 1986

Fukushima, Japan, 11 March 2011

M. Silari – Radiation and radioactivity – 6 September 2016 6 The pacific uses of radiation

M. Silari – Radiation and radioactivity – 6 September 2016 7 The pacific uses of ionising radiation

Medicine: Radiodiagnostics, nuclear medicine and radiation therapy

Energy production

Scientific research

M. Silari – Radiation and radioactivity – 6 September 2016 8 The pacific uses of ionising radiation

Industrial radiography Airport security

https://uw-food-irradiation.engr.wisc.edu/Process.html Sterilization of food and medical material

M. Silari – Radiation and radioactivity – 6 September 2016 9 The pacific uses of ionising radiation

Non-destructive measurements in archeometry

THE IRRADIATED MATERIAL DOES NOT BECOME RADIOACTIVE!

M. Milazzo, University of Milan

M. Silari – Radiation and radioactivity – 6 September 2016 10 What is ?

M. Silari – Radiation and radioactivity – 6 September 2016 11 Ionising radiation

Gamma radiation – photons or electromagnetic radiation – penetrating – “difficult” to shield Beta radiation – “light” charged particles – limited penetration in matter – “easy” to shield Alpha radiation β¯ (electron) – “heavy” charged particles – limited penetration in matter – “easy” to shield

M. Silari – Radiation and radioactivity – 6 September 2016 12 Directly and indirectly ionising radiation

Directly ionizing radiation: • fast charged particles (e.g., electrons, protons, alpha particles), which deliver their energy to matter directly, through many small Coulomb-force interactions along the particle’s track

Indirectly ionizing radiation: • X- or g-ray photons or neutrons (i.e., uncharged particles), which first transfer their energy to charged particles in the matter through which they pass in a relatively few large interactions, or cause nuclear reactions • The resulting fast charged particles then in turn deliver the energy in matter

The deposition of energy in matter by indirectly ionising radiation is a two- step process photon  electron neutron  proton or recoiling nuclei

M. Silari – Radiation and radioactivity – 6 September 2016 13 What is radioactivity?

M. Silari – Radiation and radioactivity – 6 September 2016 14 Periodic table of elements

M. Silari – Radiation and radioactivity – 6 September 2016 15 The

Nucleus: Electrons protons + neutrons

M. Silari – Radiation and radioactivity – 6 September 2016 16 The three of hydrogen

For example: the simplest chemical element, hydrogen, exists in three “variants” (ISOTOPES)

HydrogenIdrogeno Deuteron Tritium

Proton Electron Neutron

M. Silari – Radiation and radioactivity – 6 September 2016 17 Chart of nuclides

Unstable (=radioactive) nuclides ~ 3000 α-decay

β- : n --> p+ + e-

β+ : p+ --> n + e+ protons

α : AX -> A-4Y + 4He2+

Stable nuclides ~250

neutrons

M. Silari – Radiation and radioactivity – 6 September 2016 18 Radioactivity and ionising radiation

Radioactivity: the phenomenon whereby undergo spontaneous random disintegration, usually accompanied by the emission of ionising radiation

The activity of a radioactive source is its rate of decay = number of disintegrations per second

The unit of activity is the Bequerel

1 Bq = 1 s-1

(the old unit is the : 1 Ci = 3.7 x 1010 Bq)

The half-life T1/2 is the time necessary for half of the nuclei to decay

Radionuclides are either of natural origin or produced by nuclear reactions (artificial )

M. Silari – Radiation and radioactivity – 6 September 2016 19 Why does ionizing radiation pose a health risk?

M. Silari – Radiation and radioactivity – 6 September 2016 20 Effects of interaction of ionizing radiation with matter

• Biological systems (humans in particular) are particularly susceptible to damage by ionizing radiation • The expenditure of a trivial amount of energy (~4 J/kg or Gy) to the whole body is likely to cause death… • …even if this amount of energy can only raise the gross temperature by about 0.001 °C • This is because of the ability of ionizing radiation to impart their energy to individual atoms and molecules • The resulting high local concentration of absorbed energy can kill a cell either directly or through the formation of highly reactive chemical species such as free radicals (atom or compound in which there is an unpaired electron, such as H or

CH3) in the water medium that constitutes the bulk of the biological material

M. Silari – Radiation and radioactivity – 6 September 2016 21 Unit The absorbed dose is the energy deposited by a given radiation in a unit mass of matter

The unit of absorbed dose is the Gray: 1 Gy = 1 J/Kg (the old unit is the rad: 1 rad = 10-2 Gy)

Radiation protection uses the operational quantity “dose equivalent H” in

H=Q∙D 1 Sv = 1 J/Kg

Q = quality factor of the radiation

M. Silari – Radiation and radioactivity – 6 September 2016 22 Effects of radiation at the molecular and cellular level

cell cromosome

Cromatine fibre

1-10 m 1 m

DNA nucleosome

30 nm 2 nm 10 nm

Cells have a certain capacity (luckily) to repair damage

M. Silari – Radiation and radioactivity – 6 September 2016 23 The biological effects of radiation

Deterministic effects Probabilistic effects Example: burn Example: cellular mutation

M. Silari – Radiation and radioactivity – 6 September 2016 24 The biological effects of radiation

Stochastic effects Deterministic effects

No dose threshold (linear function of Dose received in short time interval dose) dose threshold: > 100 mSv (> 500 mSv)

Increase of probability by 5% per Sv for: Immediate consequences: - genetic defects - vomiting - cancer - immun deficiency - erythema and necrose

Severity of the effect is independent of Health detriments are function of the the dose received dose (and dose rate)

Delayed health detriments Lethal dose for humans: 5 – 7 Sv

M. Silari – Radiation and radioactivity – 6 September 2016 25 The biological actions of radiation

Cell membranes deterministic uncontrolled tissue indirect no-repair cell death pathologies effects (necrosis) OH free peroxydes, H O 2 radicals active substances H

Hereditary effects non-lethal mis-repair mutation CANCER stochastic DNA lesions programmed cell death direct (apoptosis) effects IONISATION deterministic excitation repair normal cell survival

biomolecule

field physics chemistry biochemistry biology, medicine

second, time scale 10-16s 10-6s 10-2s day, year, generation minute

M. Silari – Radiation and radioactivity – 6 September 2016 26 Lethal dose (LD50/30) for various organisms

Source: Martin Volkmer, Radioaktivität und Strahlenschutz, Informationskreis Kernenergie

M. Silari – Radiation and radioactivity – 6 September 2016 27 Effects associated with whole-body exposure to radiation

0to0.25grays 0.25to1gray 1to1.25grays 2.25to5grays Above5grays

No identified patho- Vomiting. Noticeable Lethal dose for 50% Some nausea. logical symptoms asso- changes to of the population. Slight fall in Almost certainly fatal. ciated with the the composition Hospitalisation leukocyte count. exposure to radiation. of the blood. essential.

Radiation and man, CEA, France

M. Silari – Radiation and radioactivity – 6 September 2016 28 Acute whole-body irradiation syndrome

Syndrome Threshold Time to Symptoms Pathology Time to appearance death Haematopoietic 1 Gy 3 weeks Lymphocyte Depletion of 2 months depletion , bone marrow infections, bleeding Gastrointestinal 5 Gy 3 to 5 hours Diarrhoea, Destruction 2 weeks fever of the intestinal mucosa Central nervous 20 Gy 0,5 to 3 Lethargy, Inflammation 2 days system (CNS) hours convulsions of CNS, oedema

LD 50 dose by acute whole body irradiation : 5 Gy

M. Silari – Radiation and radioactivity – 6 September 2016 29 Relative Biological Effectiveness (RBE)

The spatial distribution of radiation-matter interaction, and therefore biological damage, depends on type and energy of radiation (“track structure”)

M. Silari – Radiation and radioactivity – 6 September 2016 30 Dose rate dependence

Dose rate = amount of radiation absorbed per unit time

Dose Dose rate 5 tubes of aspirin In 50 seconds?? Death Or in 50 years?? Small risk or

2500 mSv In 50 seconds?? Death of radiation Or in 50 years?? Small risk

M. Silari – Radiation and radioactivity – 6 September 2016 31 What are the natural radiation levels?

To which sources are we all exposed? (voluntarily or not)

M. Silari – Radiation and radioactivity – 6 September 2016 32 Natural radiation exposures

Annual exposure to natural radioactivity in France = 2.5 mSv (3.3 mSv including medical exposures)

M. Silari – Radiation and radioactivity – 6 September 2016 33 Natural radiation exposures Annual exposure to natural radioactivity in Switzerland = 4.4 mSv (5.6 mSv including medical exposures)

M. Silari – Radiation and radioactivity – 6 September 2016 34 Natural sources of radiation

Cosmic rays

Radioactivity of terrestrial origin (radionuclides The human body present in the (radionuclides earth crust such present inside as U, Th, Ra, Rn) our body, mainly 40K)

Cosmogenic radionuclides (14C, 7Be, 3H) + medical exposures

M. Silari – Radiation and radioactivity – 6 September 2016 35 Radiation from space

L. Pinsky, Università di Houston

M. Silari – Radiation and radioactivity – 6 September 2016 36 Solar eruption: Coronal Mass Ejections

Coronal Mass Ejections and planet transit 20 Marzo – 10 Aprile 1999

The Earth SOHO – Solar and Heliospheric Observatory

M. Silari – Radiation and radioactivity – 6 September 2016 37 Terrestrial radionuclides

During the creation of the Earth, terrestrial nuclides had been

incorporated into the earth crust (T1/2 some millions to billions of years)

Nuclide Symbol Half-life

Uranium-235 235U 7.04 x 108 y 0.72% of natural

Uranium-238 238U 4.47 x 109 y 99.3% of natural Uranium

Thorium-232 232Th 1.41 x 1010 y

Potassium-40 40K 1.28 x 109 y Earth: 0.037-1.1 Bq/g

M. Silari – Radiation and radioactivity – 6 September 2016 38 Cosmogenic radionuclides

Cosmogenic nuclides are produced by nuclear reactions of cosmic particles with stable nuclei of the atmosphere

Nuclide Symbol Half-life Nuclear Reaction

Carbon-14 14C 5730 y e.g. 14N(n,p)14C Interaction of cosmic radiation with N or O Tritium-3 3H 12.3 y 6Li(n,a)3H Beryllium-7 7Be 53.28 d Interaction of cosmic radiation with N or O

Additional cosmogenic radionuclides: 10Be, 26Al, 36Cl, 80Kr, …

M. Silari – Radiation and radioactivity – 6 September 2016 39 The radioactivity inside our body

Total activity in human body Nuclide (~ 70 kg)

Potassium-40 ̴ 5 kBq Carbon-14 ̴ 3 kBq Tritium ̴ 20 Bq -210 ̴ 18 Bq Uranium ̴ 1 Bq Radium ̴ 1 Bq ̴ 0.1 Bq

TOTAL ̴ 8 kBq

M. Silari – Radiation and radioactivity – 6 September 2016 40 Radiological exposures

M. Silari – Radiation and radioactivity – 6 September 2016 41 Ambient dose equivalent rate versus altitude

Courtesy PTB, Braunschweig

M. Silari – Radiation and radioactivity – 6 September 2016 42 Air crew exposure

The average annual effective dose received by air crew is about 3 mSv

The total dose received in a return flight Milano - Los Angeles is about 100 μSv

M. Silari – Radiation and radioactivity – 6 September 2016 43 The (BED)

A general educational example (and should be taken as such!) to indicate the potential dose due to naturally occurring radioactive isotopes by eating one average-sized banana

One BED ≈ 0.1 µSv BUT this dose is not cumulative, as the principal radioactive component is excreted to maintain metabolic equilibrium

Radiation exposure from consuming a banana is approximately 5% of the average daily exposure to cosmic and terrestrial radiation ≈ 20 BED (2 µSv)

For comparison: • A flight from London to New York: 400 BED (40 µSv) • A chest CT scan: 70,000 BED (7 mSv)

WikiPedia By Evan-Amos - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=19231740

M. Silari – Radiation and radioactivity – 6 September 2016 44 Radon

M. Silari – Radiation and radioactivity – 6 September 2016 45 Radon and its progeny

Typically ≈ 40 Bq/kg of 226Ra in rocks and soil

222Rn 3.82 d The effective dose to the lung is obtained by assuming an α equilibrium factor (EF) 218Po between radon and its progeny 3.05 min

6.0 Typical indoor EF = 0.4 α MeV

214Pb β 214Bi β 214Po 26.8 min 19.7 min 164 μs

7.7 α MeV

210Pb 22 y

M. Silari – Radiation and radioactivity – 6 September 2016 46 Propagation of radon from soil into homes

• Radon is emanated from the Uranium rich soil or rocks • Radon can also be found in water • Radon escapes easily from the ground into air where it decays into its progeny.

M. Silari – Radiation and radioactivity – 6 September 2016 47 Radiation dose to humans

A. M. Mohamed et al., Journal of Physical Science and Application 2 (2012) 205–215

National Academy of Sciences, NAS-NRC Publication 848

M. Silari – Radiation and radioactivity – 6 September 2016 48 Radon map of Italy

M. Rossetti, M. Esposito, Radon levels in underground workplaces: a map of the Italian regions, Radiat. Prot. Dosim. (2014) 1–6.

M. Silari – Radiation and radioactivity – 6 September 2016 49 Radon map of Switzerland

Source: Swiss Federal Office of Public Health (http://www.bag.admin.ch/org/?lang=en)

M. Silari – Radiation and radioactivity – 6 September 2016 50 Relative risk of lung cancer

RR = ratio of the probability of a disease occurring in the exposed group versus a non-exposed group

According to WHO: Intervention level: 100 Bq/mc

100 Bq/mc Effective Dose: 5 mSv/y

Relative risk of lung cancer versus Lung cancer risk over 40 years: long-term average residential radon 0.67 – 1.25 %

Darby, S et al. BMJ 330, 223-227 (2005) M. Silari – Radiation and radioactivity – 6 September 2016 51 What are the protective means against the artificial sources of ionizing radiation?

M. Silari – Radiation and radioactivity – 6 September 2016 52 External exposure and contamination

External exposure

Contamination or internal irradiation

M. Silari – Radiation and radioactivity – 6 September 2016 53 Personnel and area classification

• Person occupationally exposed to radiation (> 1 mSv/y) – Limit < 20 mSv/y – Category A workers: > 6 mSv/y – Category B workers: < 6 mSv/y • Supervised area: area with dose > 1 mSv/y (accessible to categories A and B workers) • Controlled area: area with dose > 6 mSv/y (accessible to categories A workers, and with limited stay to category B workers) • Exposure situations: – risk of external exposure only (sealed radioactive sources, radiation generators, for example X-ray tube) – risk of internal and external exposure (use of unsealed radioactive sources) M. Silari – Radiation and radioactivity – 6 September 2016 54 External exposure

Three means to reduce external exposure: distance, time, shielding!

 Distance: the dose rate decreases with the inverse squared of the distance (from a point-like source)  Time: the dose is proportional to the time spent close to the source D = dD/dt x t  Shielding: the dose rate approximately reduces as exp(-d/λ) λ = shielding properties of the material

M. Silari – Radiation and radioactivity – 6 September 2016 55 Shielding ionising radiation

MIRION Technologies - https://www.mirion.com/introduction-to-radiation-safety/types-of-ionizing-radiation/

M. Silari – Radiation and radioactivity – 6 September 2016 56 Contamination and internal exposure

• Internal exposure: the incorporated radionuclides irradiate the organs and tissues to which they attach • Exposure lasts until the complete elimination of the radionuclides by and biological

- ingestion - inhalation - skin

M. Silari – Radiation and radioactivity – 6 September 2016 57 CERN has a an extensive environmental monitoring plan

(which does not involve the use of sheep…) Other environ- Stray radiation Air Water mental samples

M. Silari – Radiation and radioactivity – 6 September 2016 58 Operational radiation protection monitors

CERN detector systems for accelerator radiation protection

Air filled ionisation chamber REM counter Gas filled, high pressure ionization chamber Beam-on: to protect workers Beam-off: to protect workers during in areas adjacent to accelerator tunnels maintenance and repair against radiation and experiments against prompt radiation fields caused by decay of radionuclides (mainly neutrons, E < some GeV) (mainly gammas, E < 2.7 MeV)

Alarm function No alarm function

M. Silari – Radiation and radioactivity – 6 September 2016 59 Site monitors, area identification, work practices

Site Gate Monitor

M. Silari – Radiation and radioactivity – 6 September 2016 60 Personal dosimetry

People working in radiation areas wear a personal dosimeter (DIS) and an electronic dosimeter (DMC)

DIS personal dosimeter: "Legal dose”

The DMC gives a signal in the presence of ionising radiation, and a warning in case a given threshold is exceeded

M. Silari – Radiation and radioactivity – 6 September 2016 61