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RADIOISOTOPES

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illie hewitt

on 8 December 2013

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Transcript of RADIOISOTOPES

RADIOISOTOPES
What Are Radioisotopes?
Use In Medicine
Use in Industry
Radioisotope
Americium-241
Californium-252
Iridium- 192
Radium-226
Strontium-90
Plutonium-238
Cobalt - 60
Science Behind Radioisotopes
Detection
Production of Radioisotopes
Impact of Radioisotopes On Society & Environment
Radioisotopes are isotopes which are radioactive.
Isotopes are elements which occur in more than one form, that is, have same atomic number(number of protons) but different mass numbers(due to differing numbers of neutrons)
For example, carbon occurs as C-12, C-13 and C-14
Radioactive Isotopes
'Radioactivity' is the energy and mass released by spontaneous changes in the nucleus of an atom. However, 'Radiation' is energy that travels ('radiates') as waves or particles.
Radioactive isotopes are unstable, due to different numbers of protons and neutrons in the nucleus.
They emit radiation to gain stability by spontaneously releasing energy, or radiation as either particle nature, or electromagnetic radiation, called 'radioactive decay'.
The time taken for the level of radioactivity of an isotope to half is called it's half life'.
There are three types of radiation, Alpha, Beta and Gamma.
During alpha decay, the nucleus emits a particle consisting or 2 protons and 2 neutrons (helium nucleus), causing the element to change from one to another.
Beta decay occurs in two ways:
Beta Minus decay-A neutron is converted to a positron, electron and antineutrino, which are emitted as a beta particle. This process includes a gain in number of protons.
Beta plus decay- A proton is converted into a neutron, positron and neutrino, the positron and neutrino are emitted at a beta particle, resulting in reducing number of protons by one.
Gamma rays are high frequency electromagnetic waves(photons), in which the nucleus emits to rid itself of excess energy, often accompanying alpha and beta decay.
The isotope remains the same, due to no loss of neutrons or protons.
A number of radioisotopes occur naturally such as carbon-14, others are produced in a reactor, or cyclotron.
These are those elements greater then 92 in atomic number, or 'transuranic'.
Nuclear Reactor
The core of the reactor produces large amounts of neutrons.
These then collide with heavy nuclei which are in the reactor.
This causes spontaneous fission to occur, where the nucleus breaks, resulting in a number of fragments as well as some useful isotopes, which are chemically separated for use in medicine and industry.
e.g Americium-241 and strontium-90.
Cyclotron
The cyclotron involves circular shaped device with a magnetic field.
Its operates by accelerating charged particles including protons and alpha particles to high energies, to cause collision, called 'nuclear bombardment'.
New nuclei form with collision.
e.g. Mg-24 bombardment produces Na-22.
Radioisotope Generator
Uses chemical reactions with parent cell of relatively long half life, combined with positive pressure and eluent solution, to create daughter cell with short half life.
These are suitable for binding with pharmaceuticals, as use for medicine and are located within medical facilities to account for short half life.
Implications of Radioisotopes
Should radioisotope Use Be Continued?
Cobalt 60 In Medicine
Americium-241 in Industry
Americium is commonly used in industry in smoke detectors
Recent developments have established Americium as a potentail use as a Thermoelectric generator
It is also used for fluid-density gauges, thickness gauges, aircraft fuel gauges.
Thermoelectric Generator
Americium-241 is currently being researched into potential for use in an alternative for fuel for thermoelectric generaters, which fuel space craft power sources.
Americium is economically viable and is considered because of its long half life of 432 years, which means that it coould possible create an energy source which could last up to 1000 years, proving extremely useful for a space device.
Gamma decay of Am-241 generates heat. Heat is used to affect an array of thermocouples, between teo metals of a different temperature gradient, causing voltage, or energy to occur.
Smoke Detectors
A smallmount of Americium decays alpha partciles, which collide with oxygen and nitrogen in air, causing them to ionise.
This creates a steady current between electrodes.
When smoke enters, ions neutralise, breaking current and setting off detector.
Americium-241 in Medicine
Americium-241 has been used in medicine by using gamma gays to detcect Thyroid defects, via use of its gamma radiation, which is picked up by a gamma-ray camera.
It has also been used as an alternative for x-ray imaging in the way of radiography imaging.
Californium-252 in Medicine
Califorium-252 is being used as an efficient treatment for both cervical cancer and brain tumours, where other radiation treatments are unnaffective.
Rapidly dividing cells are particularly sensitive to damage by radiation. For this reason, some cancerous growths can be controlled or eliminated by irradiating the area containing the growth.
It is extremely successful in its use in bracytherapy, or ratiation therapy of cervical cancer, where extremely harmful and radioactive gamma radiation is produced by nuclear fission, causing targeted tissue to be destroyed.
Califorium-252 is produced in either a reactor or accelerator by nuclear bombardment.
The half life of 2.64 years and relatively strong radioactivity make it suitable for medical use.
Californium-252 in Industry
Californium is used in airports to detect explosives in baggage.
Californium-252 is used as a source of neutrons.
Neutrons excite nitrogen which is found in explosives to nitrogen-15, then causing emmission of gamma rays.
These gamma rays are detected and alarm airport personell of explosives!
Iridium-192 in Medicine
Iriudium-192 is used in HDR bracchytherapy of prostate cancer.
It is able to be posistioned next to the tumour, allowing direct treatmement at the sight of the tumour, as well as implanted in seed form.
It involves gamma radiation, which destroys cancerous cells.
With a half life of 73.7 days, it is suitable for use on humans.
Iridium-192 in Industry
Iridium-192 is used in industry as a means of testing and grading welds on pressurised piping and vessels, as well as in pipelines and metal castings.
Gamma radiation is emmitted via nuclear fission, and any radiation which passes through is detceted, proving faults in the materials.
The half life of 73.7 days makes it appropriate for this use as it discintegrates, leaving no traces of radioactive material in pipes.
Radium-226 in Industry
In the 1950s and during WWII, Radium-226 was used on watch dials and in military aircraft because of its ability to emmit radiation which glowed in the dark.
It decays alpha particles, and has a half life of 1601 years, proving its suitability for use in long life aircraft.
Because of it's great instability, Radium-226 is able to emmit luminescent light, which explains the faint blue glow, making it useful for dials in military aircraft and watch dials.
Strontium-90 Industrial Uses
Likewise Americium-241, Strontium-90 is used in the production of Thermoelectric generators, but for use in lighthouses, not space craft.
Strontium-90 is a Beta emmittier, and emits radiation which is reflected between the temperature gradient of two thermocouples, generating power to light the lighthouse.
Strontium-90s halflife of 28.8 years allows an extensive lifetime to create pawer for the lighthouse, whilst being of a safe strength to use on earth and reduce harmful radiation to humans.
Strontium-90 Uses in Medicine
Strontium-90 is excellent as use in treating "Superficial conjunctival squamous cell cancer", a cancer of the eye.
Beta paricles are emmitted into the eye externally, through a concave shaped applicater, targeted at the direct sight of the tumour, destroying malignant cells.
Plutonium-238 in Medicine
Plutonium-238 is used in medicine to power pace makers, which regulate the heart beat of a human with an electric shock.
Plutonium-238 is an alpha particle (helium nucleus) emmitter, which rapidly decays, causing it to give off heat.
This heat is absopbed bthe fuel capsule, then converted to energy by the thermoelectric converter.
The fuel capsule blocks radiation of gamma ray and beta ray type, which is harmful to humans.
The relatively long half life means that the pacemake does not require recharging, which requires surgical proccesses.
Plutonium Use In Industry
Plutonium-238 is used in Nuclear weapons.
Due to its high rate of emmission of alpha particles, it is a solid reactor in these weapon.
This same quality of high rate of emmission also means that it produes heat, which can be a problem in a nuclear weapon due to unstability, however this is overcome with use of cafeful management devices. Because of this unstability, Plutonium-239 is a better option for use in nulear weapons.
Plutonium-239
Plutonium-239 is suitable for use in nuclear bombs, as the high rate of nuclear fission occurs as a chain reaction, gamma radiation and thermal energy generate in a process which leads to an explosion!
Paper
Aluminium
Heavy Metal
Alpha particles have low penetration, and are stopped easily, making them suitable for use in smoke detectors, as the current is syopped.
Absorbed easily by 'geiger counters', they are of little use as tracers.
Great for treatment in medicine as they are not too penetrating, so won't kill unintended tissue.
Much too weak for use in industry as gauges.
Beta particles are ideal for ue as gauges, as particles are of medium strength, so will penetrate some materials, and not others, and it is this characteristic whuch measures density in materials and faults.
Requires long enough half life so that signal is not lost from rapid decay.
Radium-226 in Medicine

In the twentieth century, radium-226 was used in radiation treatment of cancerous tumours.
Needles containing the isotope were injected, and alpha decay destroyed the cancer cells.
However, most uses of radium-226 have been ceased, due to the extensive halflife of 1601 years, which means that the isotope remains in the body, continually emmitting radiation, having harmful effects.
Cobalt-60 in Industry
Cobalt-60 is the most commonly used radioisotope in industry, with a range of different uses. One of these uses is irradiation of food sources.
Gamma radiation is emmitted by Cobalt-60 and is used to irradiate indirectly a number of types of foods.
It serves the purpose of: delaying ripening, inhibit sprouting, extend shelf life due to reduced spoilage and to kill harmful bacteria and diseases such as salmonella which may be present in foods.
The radiation is enough to kill bacteria and other harful products on the food source, but are not strong enough to destroy the food source.
Photographic Film
The film is 'exposed' by the radiation.
This is how radioactivity was dicovered and is used in both medicine and industry to detect radiation for example levels of radiation to workers may be detected, ensuring that they are not over exposed.
Geiger-Muller Counter
The Geiger-Muller tube contains gas that ionises and produces a small pulse of electricity each time it is ionised by radiation. The counter counts the number of pulses.(HSCONLINE)
Scintillation Counter
Scintilation counters detect low energy radiation which is too weak to ionise, thus the geiger-muller counter is impracticle.
The radiation is transfered to a solvent flourescent molecule, producing light.
The light produces a pulse and the counter counts the number of pulses.
Cobalt-60 emmits gamma radiation which is used in the treatment of cancer.
Cancer cells are actively growing, thus the DNA is more succeptible to gamma ray damage than healthy cells.
A beam of radiation is externally projected into cancerous tissue, destroying the tissue and causing minimal damage to healthy tissue.
It's half life of 5.3 years means that a cannister is useful for up to ten years before requiring replacement.
BENEFITS
PROBLEMS
Food irradiaton techniques have huge implications on the food industry. Extended shelf life of food means that it is much ,ore economically viable, as produce can be stored until readiness for use!
Benifets of radioisotopes to medicine are indescribable, infanant treatments have been developed which aid in recovery of previously terminally ill diseases, with radiation therapy with isotopes such as cobalt-60.
Gauging and measuring defects in materials such as aircraft has invaluable use. Safety of aircraft and all types of people movers is directly a result of radioisotopes, and the ability to detect defects usingradiation.
All radiation is dangerous to living cells, even low exposure increases risk of genetic mutations and cancer.
Radiations ability to kill and mutate cells is the cause of these disorders.
It can take up to ten years for the effects of radiation to be visable.
A 1991 study predicted that 2.4 million people will eventually die as a result of radiation.
Nuclear weapons from isotopes of uranium and plutonium have had catastophic effects, take for example hiroshima, an elposion which killed 66 000 people directly.
Americium-241 ith a half life of 432 years means that this long storage after use, continues emmission of decay, altering genetic material and risking bone cancer.
Strontium-90 can cause bone cancer and cancer of nearby tissue as well as luekaemia.
Plutonium-239 has the potential to cause lung, bone and liver cancer.
Because radium-226 is chemically similar to calcium, it has the tendency to affect bone tissue, causing cancer and other disorders from its radioactive decay.
Iridium-192 emmission of gamma rays has the harmful effect of causing burns both internally and externally as well as increasing risks of developing cancer.
Californium-252 emmits harmfull gamma rays, and increases chance of damage to genetics, immune system, leukaemia, stillbirth, miscarriage, deformity and infertility.
Nuclear power production reduces dependence on other forms of power production such as coal, reducing use of environmentally harmful fossil fuels.
Smoke alarms use decay of Americium-241 are a huge asset in all buildings, in both the industry and doemstically warning people of fire and saving lives.
Tracing techniques in medicine allow research and understanding of functioning of the human body in medicine, by tracing reactions such as metabolism, which opens areas of treatment and pharmacuticals.
Dating of fossils such as C-14 means that studies of paleontology can estimate the age of fossils and even the age of the earth.
Detection of disease through radiography techniques including PET (positron emmission) allow detection of life threatening diseses such as brain tumours, which means that early treatment can be implementedand survival chances incresed.
Radiation
Damage to DNA
All radiotive materials produce waste which needs to be disposed of. The issue is that many radioactive materials have halflives of thouands of years, thus continue to decay for this time, releasing harmful radiation into the environment.
The way that this is disposed of is innefficient and involves dumping of containers of radioactivity in the ocean and desterts.
This brings the possbility that there may be a leak, and the surrounding aquatic environment and eventually humans are effected.
With radioactive power production there is a risk of nuclear melt down, a release of radiation due to breakdown of reactor, causing harm to people and environement.
As well as the qualitive issues associated with Radioisotopes, there is also an element of ethical consideration. The idea of distrupting natural proccesses, such as those in medical treatment reguarding radioisotopes is an arguement which will be continually supported by many conservitive goups globally.
Society
Environment
Health issues are an obvious major concern associated with use of radioisotopes in both industry and medicine. Both areas have the potential to expose humans to radiation which can cause cancer and other disorders to humans.
There is no way of measuring effects on humans as of yet, and effects can take years to be prevalant, thus the effects are truely never known as there is no way of diagnosing cancer as a result of radiation like a cold or flu virus.
However, the advances in both medicine and industry are phenominal, medical advancement in detection and treatment of diseases has saved countless lives and industrial advances have improved things such as safety from a gauge or smoke detector out os sight, if these were to suddenly be taken away, effects would be catastrophic. Adavances in medicine and industry far outweigh negative effects, however, much more reseach should go into the management of radioactive waste material.
Governments have the problem of coming up with waste programs and funding research and development.
Radioisotopes have irriversable effects on both society and the environment, medical diseases cannot be reversed and environmental waste cannot be eliminated.
Radiosotopes can have half-lives of up to thousands of years, and will continually emmit radiation into the environment and effect people unless disposed of correctly, which there is no suitable way.
Use of nuclear power reactors eliminate use of fossil fuels, reducing the effect of hyrdrocarbons on the environment in ways such as global warming, as well as the non renewable limited supply.
Uranium mining which is required for production of many radioisotopes has obious environemental effects, distruping the local ecosystem.
Nuclear power reactors use water in generating electricity, thus thermal pollution is an issue.
Areas in the environment surrounding areas where radioisotopes are produced, such as around Lucas heights have decreased in real estate value, people believe the environment is extremely harmful in radioactivity and are concerned for their health if they were to be living in the area.
Overall, I believe that the benefits of Radiosisotopes outweighs the obvious effects drastically.
However, the effects of radiation is not neccesarily a measurable issue, it is a silent killer and is one which may take years to have an effect.
There are not yet any sustainable ways to dispose of radioisotopes and I believeve that much more research should go into this avenue of radioisotopes so that the contiunation of radioisotopes is viable.
The controversy is really an issue of supply and demand, that is, do radioisotopes cure enough people of cancer and other diroders, for the number of people which develop these as a result of radiation???

Nuclear power as an alternative to fossil fuels means that the amount of fossil fuel burnt is reduced, thus the pollution to environemnt and global warming reduced.
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References
The zone of stability is a graph showning the ratio of protons and neutrons which is a stable isotope.
The penetrating power of gamma radiation means that it is suitable for radiography techniques as well as radiotheraphy. Alpha particles would be too readily absorbed for a geiger counter, so would be impracticle for radiography and beta particles are not penetrating enough.
Tracing techniques are suitable for gamma radiation, as the penetration can be picked up, however, half life should be short enough to reduce health hazards.
Gamma radiation is appropriate for the same reason for sterilizing medical eqiupment and irradiation of food, as it can kill hamful bacteria without damagiing equipment or produce.
From each of these uses, it is clear that advances in science of radioisotopes go hand in hand for medicine and industry, each area borrows research and findings and attempts to implement the uses in their field, this is evident in each of these radioisotopes as they are used in both fields, for example, gamma radiation is used for irradiation of food and streilisation of medical eqiupment, as it has th epower to kill harmful bacteria and not damage eqipment or produce.
Current plans are in place for the Australian governemnt to fund radioactive waste 'dumping facilities' in the northern territory. Just because the waste is far from cities, it does not mean that people and the environment as a whole go unaffected.
In summary,
Cause: Unstable isotopes in nature decay, releasing radiation/Industrial producion
Link:Types of production of radioisotopes(nuclear bombardment etc)
Effect:Detection of radiation, put into the many uses in industry and medicine (E.g. radiography)
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