Civilian and military uses of Nuclear energy
Civilian uses
Plant mutation breeding
Plant mutation breeding is the process of exposing the seeds or cuttings of a given plant to radiation, such as gamma rays, to cause mutations. The irradiated material is then cultivated to generate a plantlet. Plantlets are selected and multiplied if they show desired traits.
A process of marker-assisted selection (or molecular-marker assisted breeding) is used to identify desirable traits based on genes. The use of radiation essentially enhances the natural process of spontaneous genetic mutation, significantly shortening the time it takes.Countries that have utilised plant mutation breeding have frequently realised great socio-economic benefits. In Bangladesh, new varieties of rice produced through mutation breeding have increased crops three-fold in the last few decades. During a period of rapid population growth, the use of nuclear techniques has enabled Bangladesh and large parts of Asia in general, to achieve food security and improved nutrition.
Insect control
Estimates of crop losses to insects vary, but are usually significant. Despite the widespread use of insecticides, losses are likely to be of the order of 10% globally, and often notably higher in developing countries. One approach to reducing insect depradation in agriculture is to use genetically-modified crops, so that much less insecticide is needed. Another approach is to disable the insects.Radiation is used to control insect populations via the Sterile Insect Technique (SIT). SIT involves rearing large populations of insects that are sterilised through irradiation (gamma or X-rays), and introducing them into natural populations. The sterile insects remain sexually competitive, but cannot produce offspring. The SIT technique is environmentally-friendly, and has proved an effective means of pest management even where mass application of pesticides had failed. The International Plant Protection Convention recognises the benefits of SIT, and categorises the insects as beneficial organisms.
Food irradiation
Some 25-30% of food harvested is lost as a result of spoilage before it can be consumed. This problem is particularly prevalent in hot, humid countries.Food irradiation is the process of exposing foodstuffs to gamma rays to kill bacteria that can cause food-borne disease, and to increase shelf life. In all parts of the world there is growing use of irradiation technology to preserve food. More than 60 countries worldwide have introduced regulations allowing the use of irradiation for food products.In addition to inhibiting spoilage, irradiation can delay ripening of fruits and vegetables to give them greater shelf life, and it also helps to control pests. Its ability to control pests and reduce required quarantine periods has been the principal factor behind many countries adopting food irradiation practices.
Inspection and instrumentation
Radioactive materials are used to inspect metal parts and the integrity of welds across a range of industries. For example, new oil and gas pipeline systems are checked by placing the radioactive source inside the pipe and the film outside the welds.Gauges containing radioactive (usually gamma) sources are in wide use in all industries where levels of gases, liquids, and solids must be checked. They measure the amount of radiation from a source which has been absorbed in materials. These gauges are most useful where heat, pressure, or corrosive substances, such as molten glass or molten metal, make it impossible or difficult to use direct contact gauges.The ability to use radioisotopes to accurately measure thickness is widely utilised in the production of sheet materials, including metal, textiles, paper, plastics, and others. Density gauges are used where automatic control of a liquid, powder, or solid is important, for example in detergent manufacture.
Therapy
Nuclear medicine is also used for therapeutic purposes. Most commonly, radioactive iodine (I-131) is used in small amounts to treat cancer and other conditions affecting the thyroid gland.The uses of radioisotopes in therapy are comparatively few, but important. Cancerous growths are sensitive to damage by radiation, which may be external (using a gamma beam from a cobalt-60 source), or internal (using a small gamma or beta radiation source). Short-range radiotherapy is known as brachytherapy, and this is becoming the main means of treatment. Many therapeutic procedures are palliative, usually to relieve pain.A new field is targeted alpha therapy (TAT), especially for the control of dispersed cancers. The short range of very energetic alpha emissions in tissue means that a large fraction of that radiative energy goes into the targeted cancer cells once a carrier, such as a monoclonal antibody, has taken the alpha-emitting radionuclide to exactly the right places.
Hydrology
Out of all the Earth’s water resources, only 2.5% are sweet water, the rest are salty. The key for the sustainable management of water resources consist of possessing the necessary knowledge to make the right decisions.
Isotopic hydrology is a nuclear technique that is used both for stable and radioactive isotopes, to trace the movements of water in the hydrologic cycle. Isotopes can be used to investigate underground water sources and to determinate their origin, their recharge method, whether there is any risk of intrusion or contamination by salty water and whether it is possible to use it in a sustainable form. Both hydrogen and oxygen, which are the constitutive elements of water, contain mostly light isotopes. In the evaporation and condensation stages, the concentration of oxygen and hydrogen isotopes in a molecule undergoes small changes. The oceans are responsible for sending the greatest amount of water steam to the atmosphere, and when this is produced the heaviest isotopes are condensed first, then fall down as rain before the lighter ones. Thus, the furthest rain is from the coast, the less heavy isotopes it carries. Oxygen and hydrogen isotopes, contaminating isotopes such as metallic traces or chemical compounds, are as singular as a finger print, and this gives off some clues as to their origins.
Nuclear Power
Nuclear power stations generate energy through nuclear fission, the splitting apart of heavy atomic nuclei. When elements like uranium, Z=92, fission, the large nucleus splits into smaller ‘daughter’ nuclei releasing a lot of energy, which can be harnessed to produce electricity. Nuclear fuel is very energy dense with 1 tonne of uranium = 20,000 tonnes of coal and it is a low-carbon method of producing electricity. There are 16 operational nuclear reactors in the UK and they provide approximately 15% of the UK’s electricity. Nuclear batteries use the decay of radioactive nuclei to generate electricity. They are very expensive, but have a high energy density and last an extremely long time. Nuclear batteries are therefore extremely useful as power sources for equipment where there is no opportunity to ‘change the batteries’ such as pacemakers and spacecraft.
Military uses
A weapon is an instrument used to attack or defend itself. Nuclear weapons are those weapons that use nuclear technology. The origin of the development of nuclear energy occurred during the Second World War with war aims. At the suggestion of Albert Einstein, the US president initiated what would be called the Manhatan Project to develop the atomic bomb that would later be launched in Hiroshima and Nagasaky
Depending on the role of nuclear technology in the weapon, there are two types of nuclear weapons:
- Nuclear weapons that use nuclear energy to explode, as would be the case with the atomic bomb.
- Applications that use nuclear technology to propel themselves. This second category includes cruises, aircraft carriers, submarines …