Nuclear fission was first demonstrated in the laboratory in Germany in the 1930's. During WWII, serious attempts were made in Germany and in the U.S.A. to develop nuclear fission reactors for electrical power generation and for weapons production.
The American Manhattan Project, which drew upon the efforts of a large team of U.S. and expatriate scientists, was successfully concluded in 1945, when nuclear weapons were exploded over Hiroshima and Nagasaki in Japan.
The first commercial nuclear power station came on line in 1957.
Comprehensive information of nuclear power generation is available on the internet from the Australian Uranium Association, Melbourne, Victoria, Australia through the following link:- http://www.aua.org.au
The World Nuclear Association provides very full, up-to-date, worldwide information of current and proposed nuclear power reactors on its web site, http://www.world-nuclear.org
For several years, Professor Barry W. Brook, who held the Sir Hubert Wilkins Chair of Climate Change at Adelaide University and is now Head of the Faculty of Climate Science at the University of Tasmania, has collaborated with other respected international academics in peer-reviewed research into the relative benefits of the available low-carbon technologies for base-load power generation. It is clear that upon consideration of return upon investment, operating costs, safety, pollution and waste disposal, public health, long-term availability of fuel, and environmental protection, nuclear fission energy generation using 21st. century reactors is indisputably the most suitable technology for base-load power. For more information, please refer to Professor Brook's web-site, http://www.bravenewclimate.com
In Australia, we have around 30% of global resources of uranium and thorium. We are desperately in need of a major effort to build a national and export nuclear energy industry, or we will be left alone among the developed countries, without the means of securing our future energy needs. I have proposed one solution on the page An Australian Nuclear Industry. First, however, you may wish to read the briefing below:-
Economics of Nuclear Power Generation
Very careful, substantiated economic studies show that, if ALL costs of waste storage or carbon capture, and of capitalisation are considered, nuclear power is significantly less expensive than power produced by burning coal or other fossil fuels.
Unsubstantiated statements by lobby groups that "it's too expensive" are untrue.
Wind power may have a comparable cost per kWh, but is not continously available and has limited capacity per machine. However, wind power turbines may be interconnected as a grid with a number of machines spread over a wide area, and may be the best solution for the electrical power and water desalination requirements of rural areas in Australia.
Except as a by-product of the construction phase, a nuclear fission reactor does not produce significant amounts of greenhouse gases.
Combined Cycle Power Generation
The overall efficiency of power generation is considerably improved if waste heat is employed for the desalination of water or for other industrial processes.
The safety record of the nuclear power industry is far better than that of the coal industry.
There has been only one failure of a nuclear power station (Chernobyl), which caused loss of life. This was the result of obsolete design, an unforeseen design fault, and of unauthorised disregard of correct operating procedures during testing and commissioning.
The failed Chernobyl reactor was of an early Russian design in which an increase in operating temperature increased thermal power output. In this obsolete type of reactor, overheating, if not corrected, results in loss of the water which normally cools the reactor and which moderates the reaction. Chernobyl incorporated a safety shut-down graphite moderator assembly, but graphite is an ineffective moderator at high temperature, and it was not activated until all water had evaporated from the core of the reactor. In the absence of the cooling water supply, melt-down resulted and the containment of nuclear materials failed.
Most designs of Generation IV reactors are endothermic - that is, activity reduces as temperature increases, so preventing thermal runaway. Highly reliable, duplicated, mechanical and electrical safety systems are mandatory.
In the case of Fukushima, the reactor was designed to withstand earthquake and tsunami events of magnitude with a probability of 1 in 200 years. The plant was not rendered unsafe by the unpredictably-high magnitude earthquake, but by inundation of the site power generating plant by the unprecedentedly-large tsunami . This caused failure of the cooling water system, which resulted in core meltdown. Again, the Fukishima reactor was of obsolete design, and had been scheduled for de-commissioning in 2010. De-commissioning was postponed because of the onset of the global financial crisis. Three persons drowned in the flooded site. The nuclear accident caused no fatalities.
Generation IV reactor designs do not have a vulnerable cooling system.
Some early designs of nuclear reactors, known as breeder reactors, intentionally produced radioactive isotopes from natural uranium which sheathed the reactor core. The plutonium which was produced was used either to make reactor fuel elements or was incorporated in nuclear weapons. Unfortunately the plutonioum and other products of high atomic number have very long half-lives, so that they present a difficult problem of safe storage.
The new and proposed reactor types, "Generation 3A" and "Generation 4", which are listed on the World Nuclear Organisation web-site, are designed to "burn" long-lived toxic waste products and produce a small amount of low activity, short-lived wastes, which present a readily managed disposal or storage problem.
The Integral Fast Reactor, which was developed and tested at the Argonne Laboratories in the USA, finishing in 1994, is specifically designed to process and recycle nuclear waste within the reactor site. The end products are stored on-site for up to 5 years, by which time they may be disposed with other, non-radioactive wastes.
Australia has suitable secure locations on Commonwealth ground for the safe long-term storage of nuclear wastes. Alternatively, it is proposed that re-cycled wastes should be mixed with spent fuel to reduce the activity level to that of naturally occurring uranium, then buried back at the original mine site. High level wastes may be stored within the reactor shield or in secure above-ground sites for 5 years, by which time the activity level will have decayed sufficiently to permit permanent storage at the mine site or with other industrial waste.
Approximately 450 nuclear power stations of all types are currently in service.
There is a trade-off between the reactor operating temperature and efficiency. However, high temperature, high efficiency reactors require careful design to avoid the metallurgical problems which result from corrosion of the cooling system.
The type of reactor also affects the characteristics of the nuclear wastes which are produced, which may have an effect upon the operating economics of the reactor.
France generates more than 85% of its total power needs by nuclear energy, with about 10% of total capacity generated by windpower. France is a supplier of nuclear power installations to several other countries, including China, South Africa, Korea and Japan. Other developed nations, e.g. the U.S.A., the U.K., Germany, Spain and others, have re-commenced nuclear power programmes in order to replace the dwindling supplies of fossil fuels and to reduce greenhouse gas emissions. India has a large nuclear power development programme. South Korea now has a flourishing industry, building nuclear reactors for export, as do Canada and South Africa.
The CANDU Reactor
The CANDU reactor (Canadian low pressure, heavy water moderated reactor) is in service in Canada. While the initial charge of heavy water is expensive, it is not a consumable component of the reactor, and the CANDU reactor need not rely upon enriched uranium as a fuel.
The CANDU design has two separate automatic safety shutdown systems. In addition, this type of low temperature reactor becomes less active in the event of an increase in operating temperature.
It has been selected for use in China, and South Africa.
The CANDU reactor may be fuelled with un-enriched uranium or thorium. It may be maintained by replacement of spent fuel rods without being completely shut-down. It can "burn" mixed plutonium fuel, producing a less hazardous waste.
If the manufacture and re-processing of reactor fuel elements is carried out in Australia, then control of access to weapons grade material may be assured.
The Integral Fast Reactor (I.F.R.), and its successor, the Generation IV Sodium-Cooled Fast Reactor, uses a closed-cycle system for the on-site re-processing of nuclear fuels. It may utilise the long-half-life fuel waste from conventional thermo-nuclear reactors. It eventually produces a trivial amount of short-half-life waste which can be stored on-site, until it is safe for buried disposal. It ensures almost complete "burning" of uranium and thorium fuel sources, without producing plutonium.
It is estimated that there is now sufficient suitable nuclear waste, mainly weapons-grade plutonium, to supply the world's energy requirements, using the I.F.R., for 1,000 years. This is a supreme example of the possible use of appropriate terchnology, to turn the problem of waste disposal into the benefit of safe, cheap power,
Australia has about 30% of the world's reserves of uranium, and perhaps three times as much thorium. Only 0.72% of naturally-occurring uranium is the fissile isotope, U235, which is suitable for use in nuclear fission reactors, and it is separated from natural uranium by a most expensive enrichment process. Recent Australian research has developed a much less expensive laser enrichment process, the Silex process.
Almost 100% of thorium is usable as reactor fuel, and no enrichment is necessary, so that it is a much more efficient nuclear fuel. Thorium is "fissile, but not fertile", that is, unlike enriched uranium or plutonium, it does not produce excess neutrons as a result of nuclear fission. It cannot produce a chain reaction, and reactor activity ceases if the neutron source is removed or shut-down.
It is almost impossible to produce weapons grade material in a reactor which uses the thorium fuel cycle.
Generation IV reactors may be produced in a wide range of sizes, or delivered to site by barge, so that they are suitable for installation in remote locations. The waste heat from a reactor may be used for the production of potable water at low cost, and with improved efficiency of power generation. In operation, they produce no greenhouse gas emissions.
Small floating nuclear reactors of established, safe design may be constructed quickly in the developed countries. The possibility of mass construction techniques and the development of a trained labour force, with long-term employment, makes this course of action potentially attractive.
They may be deployed flexibly to provide non-polluting power stations, co-generating potable water supply. at any coastal location. They require a minimum of infrastructure support. The supplier may retain full control of the reactor fuel elements, preventing any possibility of the proliferation of nuclear weapons.
This is probably the quickest way of providing efficient power generation capacity to the developing countries, without producing greenhouse gas emissions. The same facilities could be used to provide regular major maintenance, returning the complete reactor by sea to the place of manufacture. A new or re-furbished reactor could replace the reactor which is being maintained.
Whyalla in South Australia would be an ideal location for the mass construction of floating reactors. It has an existing steelworks, a shipyard with dry dock and deep water harbour facilities, an established sub-contractor area, adequate housing and civic resources, and access to electrical power. It is conveniently located for access to uranium mining facilities, where fuel enrichment and processing facilities could be established.
Australia has about 30% of the world's reserves of uranium. Uranium is the most commonly used fuel for nuclear reactors and so will be in increasing demand for the task of reducing global warming.
For political, moral, ecological and financial reasons, we will be unable to resist international pressure to expand the mining and export of uranium.
The processed uranium ore, uranium oxide or "yellowcake" consists mainly of the oxide of Uranium 238, with about 0.72% of the oxide of U235. It is moderately radioactive.
To sustain a chain reaction in most designs of commercial reactor, the proportion of U235 must be enriched, typically to between 3% and 5%. For weapons applications, the enrichment is increased, to in excess of 90%. Enrichment is usually accomplished by centrifuging or, less commonly, by the diffusion of gaseous uranium hexafluoride through a semi-permeable membrane. Since the difference in molecular weight of compounds of the two isotopes U238 & U235 is very small, the difference in the rates of diffusion or separation is also small. In order to achieve the necessary level of U235 hexafluoride which is required, the enriched gas stream is returned to the input of the separator and is recycled many times. Note that uranium which has been enriched for use in nuclear power stations is unsuitable for use in nuclear weapons, and is unable to cause an explosion.
The enriched uranium is converted back to uranium oxide and manufactured into fuel assemblies, as required for the design of reactor which is to be fuelled.
As noted above, Australian scientists have recently developed a more efficient, less expensive, laser isotope separation process, the Silex process.
It is recommended that Australia's uranium output should be enriched and manufactured into fuel assemblies at or near to the mine sites, to ensure security of the material, to enable the return of waste material to the ore body, and to add value to the exported fuel.
The spent fuel from a reactor may be re-used, to produce more energy, by adding enriched uranium, to produce MOX (Mixed Oxide) fuel. This has the added benefit of converting plutonium into less hazardous nuclear wastes, which facilitates the safe storage of wastes. Also, the extraction of weapons-grade material from spent fuel assemblies is more difficult.
MOX fuel is used in 30 European reactors and an additional 20 reactors are awaiting licenses. Japan planned to use MOX fuel in a third of its reactors by 2010. In addition, both Russia and the United States may possibly use MOX fuel in five reactors and six reactors, respectively. The fuel is produced in commercial quantities at four separate plants located in Belgium, the United Kingdom, and France.
Thorium as a Fuel
Thorium is more plentiful in ore reserves than uranium and may be used as a reactor fuel. It is easier to process than uranium ore and the wastes are less hazardous to store, with shorter half-life. In Australia, it is estimated that thorium is approximately 3 times more abundant than uranium. It is readily separated from uranium ore.
India, and several other countries, are constructing thorium-fuelled nuclear reactors. The mining and processing of thorium in Australia should be encouraged.
Nuclear Heat Sources
Nuclear waste which is thermally active, but which is not capable of sustaining a chain reaction, may be stored in unmanned low power installations to provide heat and to generate electricity for such applications as the desalination of water, pumping etc.
Such installations may be shielded with concrete and with an earth backfill, to ensure secure and radiologically safe storage of suitable thermally-active wastes.