SourcesSourcesof of rradiationadiation

Sources of radiation exposure Sources of radiation exposure to people populationto people population

Background Background radiation radiation

• Terrestrial radioactivity

• Cosmic radiation

• Internal radioactivity

Terrestrial Terrestrial rradiationadiation::external and internal exposureexternal and internal exposure

U-238 Ra-222

Th-232 Ra-220

Radon is a gasRadon is a gasIt is naturally occurringIt is naturally occurringYou can not see or smell You can not see or smell ititIt enters buildings from It enters buildings from the soil beneath themthe soil beneath them

April 21, 2023April 21, 2023 55

Uranium

Radium

Radon

1,600 years1,600 years

3.8 days3.8 days

4.5 billion years4.5 billion years

Radon - Radon -

Decay product of Decay product of radiumradiumEstimated to be the Estimated to be the second leading second leading cause of lung cause of lung cancer cancer Nearly one in 15 Nearly one in 15 homes in the U.S. homes in the U.S. has a high level of has a high level of indoor radon indoor radon

66

Radon diffusion from soilsRadon diffusion from soilsRn is a gas, and can easily leave rocks and soils Rn is a gas, and can easily leave rocks and soils through fractures /openings into pore spaces through fractures /openings into pore spaces between grains of soil. between grains of soil. If Rn can move easily in the pore space, then it If Rn can move easily in the pore space, then it can travel a great distance before it decays, and it can travel a great distance before it decays, and it is more likely to collect in high concentrations is more likely to collect in high concentrations inside a building. inside a building. Method & speed of Rn's movement controlled by Method & speed of Rn's movement controlled by water in the pore space (the soil moisture content), pore water in the pore space (the soil moisture content), pore

space in the soil (the porosity), and "interconnectedness" space in the soil (the porosity), and "interconnectedness" of pore spaces that determines the soil's ability to of pore spaces that determines the soil's ability to transmit water and air (called soil permeability).transmit water and air (called soil permeability).

April 21, 2023April 21, 2023 77

April 21, 2023April 21, 2023 88

Radon Movement into HomesRadon Movement into HomesMost houses draw less Most houses draw less than one percent of their than one percent of their indoor air from the soil; indoor air from the soil; remainder comes from remainder comes from outdoor air, which is outdoor air, which is generally quite low in generally quite low in radon. radon. Houses with low indoor air Houses with low indoor air pressures, poorly sealed pressures, poorly sealed foundations, and several foundations, and several entry points for soil air, entry points for soil air, however, may draw as however, may draw as much as 20 percent of much as 20 percent of their indoor air from the their indoor air from the soil.soil.Even if the soil air has Even if the soil air has only moderate levels of only moderate levels of radon, levels inside the radon, levels inside the house may be very highhouse may be very high..

April 21, 2023April 21, 2023 99

High background areasHigh background areas

Cosmic Cosmic rradiationadiation

Internal Internal rradioactivityadioactivity

Radioactivity

in diet• potassium-40

• lead-210

• polonium-210

Background radiationBackground radiation

Cosmic - 0.3 mSv

Food - 0.4 mSvTerrestrial - 0.3 mSv

Radon - 2 mSv

Air

April 21, 2023April 21, 2023 1414

Natural background radiation doses in Europe

Naturally occuring background levels of radiation can typically range from 2.0 to 4.0 mSv a year

Artificial sources Artificial sources of ionizing radiationof ionizing radiation

Radioactive sources Radioactive sources

Electric generators of ionizing radiation Electric generators of ionizing radiation

Activities using nuclear energy:Activities using nuclear energy: nuclear weapons nuclear weapons nuclear reactors nuclear reactors

Radioactive sourcesRadioactive sources

Radioactive sources are present in the sealed (normally non spreadable) and unsealed form (spreadable):

GammagraphyGammagraphy essentially uses as sources essentially uses as sources iridium-192 and sometimes cobalt-60 iridium-192 and sometimes cobalt-60

NeutrongraphyNeutrongraphy uses sources of neutrons like uses sources of neutrons like californium-252 or an americium/beryllium californium-252 or an americium/beryllium couple. couple.

BetagraphyBetagraphy uses beta sources like carbon-14. uses beta sources like carbon-14.

Chemical and biological radiation-treatmentChemical and biological radiation-treatment uses gamma radiation sources cobalt-60 or uses gamma radiation sources cobalt-60 or caesium-137. caesium-137.

Radioactive sources in medicineRadioactive sources in medicine

In medicine there are three uses In medicine there are three uses for non-sealed radioactive nuclides:for non-sealed radioactive nuclides:

Biological analyses:Biological analyses: radio-markers have been replaced radio-markers have been replaced progressively by non-radioactive markers. progressively by non-radioactive markers.

Medical imaging:Medical imaging: nuclear medicine department use nuclear medicine department use radio-pharmaceuticals for diagnostics, which are radio-pharmaceuticals for diagnostics, which are ingested by the patient to obtain an image of the ingested by the patient to obtain an image of the tissue or organ while it is functioning.tissue or organ while it is functioning.

Therapy:Therapy: radio-pharmaceuticals can constitute the radio-pharmaceuticals can constitute the treatment itself, for example iodine 131 for the treatment itself, for example iodine 131 for the treatment of thyroid cancer. treatment of thyroid cancer.

Electric generators Electric generators of ionizing radiationof ionizing radiation

The industrial applications of electric generators of ionizing radiation are neighbors of radioactive sources.

Medical applications comprise radio-diagnostics and radiotherapy:

Medical radio-diagnostics is man’s largest source of exposure to ionizing radiation. It uses standard radiography equipment and X-scanners.

The electric generators used in radiotherapy are electron accelerators of medium energy (20 million volts) which enable a beam of electrons or X-rays to be obtained.

In the research sector the large accelerators and scientific instruments are used to study the fine structure of matter.

Effective doses from mEffective doses from medical edical eexposurexposure

Effective dose (mSv)

Equivalent period of natural radiation

Radiography

Chest 0.02 3 days

Pelvis 1.0 6 months

IVP 4.6 2.5 years

Barium studies 9.0 4.5 years

CT (Chest, Abdomen)

8.0 4 years

Nuclear Medicine

Thyroid imaging 1.0 6 months

Bone imaging 3.6 1.8 years

Nuclear WeaponsNuclear Weapons

April 21, 2023April 21, 2023 2121

Nuclear weaponsNuclear weapons

Nuclear weapons can function by two very different modes – nuclear fission or nuclear fusion:

Fission armsFission arms employ the principle of an employ the principle of an uncontrolled chain reaction, i.e. each fission uncontrolled chain reaction, i.e. each fission reaction leads to several further fission reactionsreaction leads to several further fission reactions

Fusion arms (thermonuclear)Fusion arms (thermonuclear) use the fact that use the fact that the union of deuterium and tritium to form a the union of deuterium and tritium to form a single nucleus of helium liberates a very large single nucleus of helium liberates a very large amount of energyamount of energy

April 21, 2023April 21, 2023 2323

Extensive above ground testing in US and USSR 1946-1962 Above ground testing by other countriesWaste generated from weapons grade uranium and plutonium production

spent nuclear fuel --- processing to enrich U and Pugenerates large amount of other radionuclide "waste"which has to be "discarded" -- buried? stored?

Summary number of explosions of Summary number of explosions of nuclear weapons from 1945 to 1998nuclear weapons from 1945 to 1998

CountryCountry Years Years Number of Number of explosionsexplosions

USAUSA 19451945 –– 1992 1992 10301030

RussiaRussia 19491949 –– 19911991 716716

FranceFrance 19601960 –– 19971997 210210

Great Britain Great Britain 19501950 –– 19601960 4444

ChinaChina 11964964 –– 19961996 4545

IndiaIndia 1974, 19981974, 1998 66

PakistanPakistan 19981998 55

April 21, 2023April 21, 2023 2525

Cesium – 137 137Cs+

Iodine - 131 131I-

Nuclear Reactor Waste & Atomic BombsRadioactive nuclear fisson products

Radionuclide behavior -- Iodine and Cesium

UraniumUraniumUnderground and open pitsUnderground and open pits– In situ In situ leaching has been usedleaching has been used– radon & gaseous products a problem for radon & gaseous products a problem for

workers - not much for general publicworkers - not much for general publicUranium MillsUranium Mills– Ore ground to sandOre ground to sand– Acid/alkaline leachAcid/alkaline leach– Concentrated by ion exchange / solvent Concentrated by ion exchange / solvent

extractionextraction

2626

TransportationTransportation

Radioactive materials are transported from the Radioactive materials are transported from the milling location to the conversion location, then from milling location to the conversion location, then from the conversion location to the enrichment location, the conversion location to the enrichment location, then from the enrichment location to the to the fuel then from the enrichment location to the to the fuel fabrication facility, and finally to the power plant. fabrication facility, and finally to the power plant. These materials are transported in special These materials are transported in special containers by specialized transport companies. containers by specialized transport companies. People involved in the transport process are trained People involved in the transport process are trained to respond to emergencies. In the US, Asia, and to respond to emergencies. In the US, Asia, and Western Europe transport is mainly by truck, and in Western Europe transport is mainly by truck, and in Russia mainly by train. Intercontinental transport is Russia mainly by train. Intercontinental transport is usually by ship, and sometimes by air. Since 1971 usually by ship, and sometimes by air. Since 1971 there has been over 20,000 shipments with no there has been over 20,000 shipments with no incidents and limited operator exposureincidents and limited operator exposure . .

2727

Nuclear Fuel CycleNuclear Fuel Cycle

April 21, 2023April 21, 2023 2828Source: http://www.sonic.net/~kerry/uranium.html

Consumer productsConsumer products

Tobacco Tobacco 210210Pb and Pb and 210210Po Po

Coal//natural gas Coal//natural gas

Th and U in ceramics and glass Th and U in ceramics and glass

Airport x rays Airport x rays

April 21, 2023April 21, 2023 2929

Man-made Sources of Man-made Sources of RadiationRadiation

Consumer productsConsumer products– Television setsTelevision sets– Fossil fuel: coal, gasFossil fuel: coal, gas

Air travelAir travel

Luminous compoundsLuminous compounds

Building materialsBuilding materials

Nuclear fuel cycleNuclear fuel cycle

Above-ground bomb testsAbove-ground bomb tests

April 21, 2023April 21, 2023 3030

EffectiveEffective doses doses received received duringduring various various types of types of workwork

‘Non-coal’ mining16.3 milisieverts

Dos

e in

mili

siev

erts

The San Salvador accident The San Salvador accident in February 1989 in February 1989

Three employees at an industrial sterilization plant in Three employees at an industrial sterilization plant in San Salvador were using a very significant Co-60 source of San Salvador were using a very significant Co-60 source of 600 TBq (more than 15,000 Ci). They were seriously irradiated 600 TBq (more than 15,000 Ci). They were seriously irradiated due to obsolete plant and their not being aware of the risks. due to obsolete plant and their not being aware of the risks.

As a result of their position and the time they spent As a result of their position and the time they spent near the source, the whole body exposure doses they near the source, the whole body exposure doses they received have been estimated at 8 Gy, 4 Gy and 3 Gy, received have been estimated at 8 Gy, 4 Gy and 3 Gy, respectively. respectively.

Vomiting appeared less than two hours after Vomiting appeared less than two hours after exposure. The three victims were referred to the nearest exposure. The three victims were referred to the nearest hospital because they felt very tired and could not stop hospital because they felt very tired and could not stop vomiting. They did not present any other sign of acute vomiting. They did not present any other sign of acute exposure. Although they had mentioned their work in a plant exposure. Although they had mentioned their work in a plant using ionizing radiation, they were diagnosed as having food using ionizing radiation, they were diagnosed as having food poisoning. poisoning.

Acute irradiation syndrome was only recognized three Acute irradiation syndrome was only recognized three days later when another patient presented with erythema, days later when another patient presented with erythema, skin burns, nausea and vomiting and told them that there had skin burns, nausea and vomiting and told them that there had been a technical accident at an irradiation plant. been a technical accident at an irradiation plant.

Paints for luminous watch faces

In the 1920s and 1930s the clock making industry used radium 226 and 228 in radio-luminescent paint for watches. At this time, the risk from alpha emitting radio-elements was almost unknown.

The workers who painted the luminous faces had the bad habit of tapering their brushes with their lips. Every time they did this they ingested several becquerels of radium. The fact that radium and calcium are chemical homologues, resulted in rare bone cancers appearing starting from the 20s, in the form of carcinoma of the sinus of the face.

An epidemiological enquiry demonstrated the link between exposure to radium and the risk of bone cancer in 2,403 workers, whose ingestion of quantities of radium could be evaluated. 64 were suffering from osteosarcoma whereas 2 cases of this type of cancer would have been expected statistically.