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Ionising Radiation - Coggle Diagram
Ionising Radiation
Sources :warning:
Cosmic :warning:
10% average annual dose
Natural
Charged sub atomic particles
Released by natural processes in the sun
Absorbed when they reach earth
Release high energy electromagnetic radiation
Gamma Rays
Gamma rays from the lithosphere :warning:
Many radioactive isotopes
Release different type of radiation as they decay
Only gamma rays that penetrate well enough
Travel from underground to earths surface
Internal radiation from the body :warning:
Activation products (upper atmosphere)
Radioisotopes from the ground
Enter the body via food/water
Decay inside the body and release radiation
Radon from the ground :warning:
Radioisotopes in underground rocks decay
Usually absorbed by surrounding rocks
When some uranium atoms decay gaseous radionuclide - radon is produced
Radon is unstable
Releases alpha radiation
Travels up cracks in overlying rocks/escapes into the atomsphere
Passes through foundations of buildings
Becomes concentrated inside buildings
Devon/Cornwall have high radon levels - due to underground rocks
Ventilating building foundations can be used to blow out radon before it enters the building
Medical Exposure :warning:
Used in many medical procedures
Have benefits but involve risks
Procedures :red_flag:
Xray Photography
Gain information of the inside of the body
Broken bones
Dental (to find decay)
Xray Radiography
After injecting radio-opaque dyes
Blockages
Kidney stones
Blocked arteries
High doses to kill cancerous tissue
Radio labelled substances
track the passage of that substance in the body
Check for blockages
Occupational exposure :warning:
Working in certain industries increases exposure
Nuclear electricity generation :forbidden:
Manufacturing industry :forbidden:
Mining :forbidden:
Medical radiographers/radiologists :forbidden:
dentists/dental technicians :forbidden:
Workers who use radioactive sources to test paper/steel thickness :forbidden:
Research scientists who use radio labelled tracer substances :forbidden:
Aircraft flight crews :forbidden:
Atomic weapon fallout :warning:
Atmospheric testing/usage released radioactive material
Carried by winds
Contaminated all parts of earths surface
No testing since the 1980s
Consumer products :warning:
Smoke detectors
Camping gas mantles
Ceramics
Granite worktops
Small increased dose to public
Industrial radiation discharges :warning:
Industries that use radionuclides release some
Nuclear energy generation
Nuclear weapon manufacture
Improved processes
filters for gaseous emissions
Ion-exchange sands for liquid releases
Background radiation cannot be avoided :warning:
Sun, Rocks, Food
Uses :explode:
Healthcare :explode:
Sterilising heat sensitive equipment
Cancer Treatment
Xray/CT scans
Industry :explode:
Thickness of rolled paper/metal
Testing aircraft jet engines
Strengthening Polymers
Creates cross links in molecules
Surgical gloves
Heart surgery balloons
Vehicle Tyres
Oil/Gas exploration - test porosity
Agriculture :explode:
Pest control
Sterilise food
Sterile male insect pest control
Production of mutations - Crop breeding programs
Scientific research :explode:
Radio-labelled tracers - track movement within organisms/the environment
Nuclear Fission/Fusion :explode:
Nuclear weapons
500 nuclear test explosions took place upto 1980
Nuclear electricity
Nuclear fusion using uranium & plutonium
Ship propulsion
High energy density of nuclear fuel
ships are propelled by nuclear reactors
Rarely need to be refilled
Dont need energy for combustion
Factors that effect the impact :!:
Properties of different types :!!:
Impact is determined by the different types
Power to penetrate
Distance they can travel
Ease they're absorbed
Poor penetrating power - easier to be absorbed
Ionising radiation penetrates - energy from the less penetrating types will be absorbed
More serious local damage
Relative Biological Effectiveness (RBE)
Measure of the comparative effects
More damaging - higher RBE
ALPHA :!!:
Very easily absorbed
Travels short distances
20 RBE
Absorbed by clothing/dead skin
Outside the body are usually safe
Ingested = very dangerous
More concentrated damage
Increased risk of free radical interactions
BETA :!!:
Moderately easily absorbed
Travels medium distances
1 RBE
Moderately dangerous
Sources near body still pose a risk
GAMMA (& XRAYS):!!:
Not easily absorbed
Travel long distances
1 RBE
Lower danger
Longer distance of travel means distant sources are a risk
NEUTRONS :!!:
Moderately easily absorbed
Travel medium distances
2-10 RBE
Very dangerous
Still pose a risk after they are absorbed
Some atoms are changed when bombarded by neutrons - become activation products
Stable nucleus becomes a radionuclide when bombarded
May later decay and release ionising radiation
Density of the material will determine how far it will travel
Denser more easily absorbed
Half life and health risks :!:
All atoms of an unstable isotope will have the same probability of decaying during a certain time period
Likelihood of decay is not affected by the number of atoms present
For the mass there is a predictable rate at which atoms will decay and emit ionising radiation
Rate us expressed as half life
Length of time it takes for half the original isotope to decay
1/2, 1/4, 1/8, 1/16, 1/32, 1/64 etc
Half lives
Uranium 4.5 X 109 yrs (Natural in rocks)
Iodine 8 days (Fission in reactors)
Plutonium 24,400 yrs (Reactors by neutron bombardment)
Shot half lives release radiation rapidly
Dangerous but don't pose danger for long
Short-term precautions may be sufficient
Long half lives pose a danger for a long time
Emit small amounts of radiation in any given time period
Level of danger is quite low
Half lives of several decades
Rate of radiation release is high
People can be exposed for most or all of their lives
Short term precautions are inadequate
Effects on living tissue
Ions called free radicals are released
Unpaired electrons are highly reactive
Biologically damaging reactions
Damage to the nucleus :no_entry:
Affects existing cell and future cells
Mutations
Rapidly dividing cells (Skin/gut) - easily affected
Genetically active
Damage to other parts of the cell :no_entry:
cell cannot function properly
Lower levels of damage may cause no long term effects
Intact nucleus can co-ordinate repair
Somatic effects :no_entry:
damage to general body cells/organs
Gonadic :no_entry:
Damage to cells of ovaries/testes
Chronic effects :no_entry:
appear slowly
In proportion to radiation doses received
Acute effects :no_entry:
Appear quickly
Shorter period of time more damaging (more free radicals)
Cells dont have time to repair
Large doses (nuclear accident)
More serve impact - rapid death
Damage to bone marrow, immune system, gut (haemorrhage), blood loss
Exposure and Contamination :no_entry:
Exposure
Absorption
Person must be close enough
Contamination
physically carrying
exposure will continue as long as its on the person
Sources are sealed inside a container may expose people but they cannot become contaminated
Activation products :no_entry:
Exposure doesn't cause the material to become radioactive
Exposure can cause a previously stable nuclei to become radioactive
Most often found in the structures of a nuclear reactor
Monitoring radioactive materials
Units for measuring
Becquerel activity of the source
Gray measured of absorbed dose
1 Gy is the absorption of one joule of radiation energy per kilogram of matter
Sievert - measure of effective dose that allows for the differing effects of the different types of radiation
Worker monitoring
Monitoring the environment and testing the workers
Personal dosemeters - current exposure reading
Photographic film badges - long term
air monitors detect atmospheric particles
Contamination monitors - monitor workers as they leave
Critical Pathway Analysis (CPA)
Critical Group Monitoring (CGM)
Environmental Monitoring
About :star:
Naturally occuring
Threat to health
Radioactive materials need to be managed
Pollution :star:
Weapon testing
Waste disposal
Accidents
Transportation
Storage
Risk:Benefit analysis :check:
Nothing is completely safe
Decided whether the benefits out weigh the risks
Can be difficult
Symptoms may take a long time to develop
Especially chronic/low exposure
Some effects may difficult to identify
accurate data on the impacts of humans not avaliable
accurate data on exposure not available (accidental)
People who benefit and those who face the risks may not be in the same place
Benefit from nuclear electricity may live in a different country to the power station
Risks can be offset by reduction of other risks
XRAY reduces invasive surgery risks
Control of exposure :recycle:
Principles :recycle:
ALARA
As low as reasonably achievable
situations should be managed
BATNEEC
Low exposure
Best Available Technology Not Entailing Excessive Cost
Assessment of excessive cost depends on level of risk
Strategies to reduce exposure : :recycle:
Closed sources :check:
Prevents workers coming into direcr contact
Enclosing sources in a container
Close source of alpha emitters may reduce exposure to zero
Remote handling techniques
Source cannot be contained = worker can wear a sealed suit
Reducing period of exposure :check:
Minimise the time close
Materials to absorb the radiation :check:
materials are used as barriers
To prevent radiation reaching the workers
Choice/thickness of material will depend on radiation involved
Protective clothing :check:
minimise contact
Distance from source :check:
Radiation follows Inverse Square Law
Distance from the source is increased - more proportional drop in exposure
Doubling the distance from the source reduces exposure 1/4 of its previous level
Dose received = 1/Distance*2
Decontamination :check:
Washing
Scrubbing
Exfoliating scrubs
Swallowing stable potassium iodine tablets prevents uptake of radioactive iodine
Good waste management :recycle:
High level
Used uranium rods
Vitrification - dried powered solid waste mixed with molten glass, solidified in stainless steel containers
Air cooling removed radioactive decay
Sellafield, cumbria
Intermediate level
Metal tubes that surrounded the fuel rods (become radioactive)
Filters from waste processing
Mixed with cement and stored in stainless steel drums
Sellafield
Low level
Solid
General equipment
Clothing
In contact with radioactive material
sealed in thick polythene bags inside steel drums inside steel truck containers in a concrete lined landfill site
Drigg, near Sellafield
Liquid
Waste solutions from used fuel reprocessing and storage
Filtered then discharged (ion exchange)
Gases
Released from used fuel during storage/reprocessing
filtered then released