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by Ian Hore-Lacy,
Australian Uranium Association, Melbourne
Science teachers have a great opportunity to utilise the many technical aspects, the environmental dimensions, the political concerns and the human interest aspects of nuclear energy (as well as the application of radioisotopes) to teach several elements of science.
The AUA's Information Centre has a range of resources to assist this, see Education and Briefing paper sections of the web site in particular.
We start from the fact that Australia is a major exporter of uranium, something which is contentious in some quarters, but this can only help the teacher.
The rationale for uranium exports is rapidly-growing electricity demand coupled with greenhouse and other environmental concerns. Energy securioty is a further driver of demand in the northern hemisphere
Electricity demand is growing at almost double the rate of overall energy demand, indeed, greater use of electricity is a means of energy conservation in many cases.
Uranikum exports comprise about 40% of Australia's energy exports, in thermal terms.
In chemistry there are straightforward inorganic reactions as well as organic solvent extraction processes involved in the milling of uranium ore to produce uranium oxide concentrate (U3O8, or UO2 + 2UO3) for export from Australia.
Looking further around the loop of the nuclear fuel cycle reveals further such chemistry, at least for the portion of the world's used fuel which gets reprocessed and recycled. The notion of recycling a fuel is itself intriguing!
See: Chemistry of Uranium education paper, and various briefing papers.
Anything "nuclear" tends however to be monopolised by the physicists, and nuclear energy brings a number of issues to the fore as being topical and occasionally controversial, - a godsend for any teacher!
Physics
The physics of the reactor core is a good starting point.
What moderators are used and why?
How do control rods work and why did the peculiar design of those formerly in Soviet RBMK reactors contribute to the Chernobyl disaster?
How do increasing levels of enrichment and increasing fuel burnup affect reactor operation and the demand for Australia's uranium?
How do various new reactor designs improve the thermodynamics of generating the electricity, - especially the proposed high temperature gas turbine helium-moderated design?
See: Physics of Uranium education paper and various briefing papers.
Enrichment technologies started with the calutrons in the 1940s then progressed to diffusion plants and centrifuges using gaseous UF6.
The only type of laser enrichment technology now being developed is Australian.
What significance do these have to possible Australian upgrading of its uranium supplied to world markets?
Why is enrichment priced per SWU?
As a non physicist, I have never seen a more impressive demonstration of Charles' Law than the French diffusion enrichment plant at Tricastin, - 3000 megawatts driving the compressors, then two giant cooling towers and a crocodile farm getting rid of the waste heat!
As well as uranium and plutonium which may be recycled, Used fuel contains a mixture of fission products and transuranic isotopes, with a wide range of half lives.
What is the best trade-off between allowing radioactivity to decay and the imperative to dispose of such wastes at an early stage in a secure and permanent repository?
When should reprocessing take place to separate the wastes from the recyclable uranium and plutonium?
What is the proportion of different isotopes are in plutonium recovered from spent fuel? (reactor-grade Pu)
Why are the minor acrtinides better able to be burned (to fission products) in a fast neutron reactor?
Given the small quantities of plutonium required to make a bomb, why is there no problem in transporting this with 15 kg as oxide packed into a single cylinder?
Why is reprocessed uranium, containing some U-232 and U-236, not so readily useable in fresh mixed-oxide (MOX) fuel as depleted uranium (though with lower U-235 content)?
How does uranium oxide fuel enriched to 3.5% U-235 compare with MOX fuel containing 7% reactor-grade plutonium?
Looking at MOX fuel fabrication, what shielding is necessary here, due to Pu-240, while virtually none is needed in a fresh uranium oxide fuel plant?
What criticality considerations would govern the introduction of weapons plutonium (>90% Pu-239) into the MOX fuel fabrication for reactors and how might this be handled?
Why is MOX considered the only definite way of removing weapons plutonium from the face of the earth?
Why is boosting the Pu content of MOX a cheaper way of providing fuel for high-burnup reactor use than increasing ordinary fuel enrichment from say 3.5 to 4.0% U-235?
Why is americium a problem in aged plutonium?
Where does the Am-241, almost ubiquitous in household smoke detectors, come from?
Regarding high-level waste (or used fuel) disposal, what considerations should govern this?
How are they being implemented in different parts of the world?
Today more than ever it is significant that nuclear power is the only energy-producing industry which takes full responsibility for all its wastes and fully costs this into the product.
My observation in several countries is that this waste management (with some recycling) is undertaken very well, without any significant incidents, and is of course it is now a multi billion dollar industry in itself.
What other toxic industrial wastes are as competently and reliably managed as nuclear wastes from electricity production?
The quantities involved are relatively very small, the potential hazards, though large, have been well recognised from the outset of the industry, and they have been managed accordingly.
What are the physical and chemical principles involved in safely isolating high-level wastes?
When reactors are decommissioned, what are the radiological problems involved from activation products, how have they arisen and how are they managed?
And during operation, why are certain designs of pressure vessels more prone to embrittlement due to neutron bombardment than others?
The safety of nuclear power reactors is a prominent issue.
Certainly Chernobyl in 1986 was an unmitigated disaster, and it tragically underlined whay no reactors like that could ever have been built outside the old Soviet Union. So does it have any more relevance to the safety of most of the world's reactors than airline crashes in Outer Mongolia or west Africa have to my safety travelling on Qantas?
In fact, like adverse experience in civil aviation, it is worth looking at the very beneficial consequences, so that Soviet-designed reactors are vastly safer now than they were then, though some older ones still fall short of standards accepted and required in the West. The newest ones conform to western standards.
There has been unprecedented cooperation between East and West in achieving this improvement in both hardware and safety culture, incidentally.
Chernobyl remains the only serious uncontained accident in some 12,600 reactor-years of operation. How do other industries compare with that?
Environment
Environmentally the most obvious aspects of nuclear energy are radiation and how it is controlled, and the virtual absence of other pollution.
But global warming is now a key aspect of what energy sources are used for electricity, as we are frequently reminded.
What would be the effect of increasing or decreasing nuclear energy use? Today electricity generation produces about 9.5 billion tonnes of CO2. Nuclear energy saves the emission of a further 2.5 billion tonnes per year, almost five times Australia's total from all sources.
What are the comparative figures for CO2 emissions from the full lifecycle of coal, gas, and nuclear? - in grams per kilowatt-hour.
Without nuclear the total amount of CO2 from electricity would be nearly 12 billion tonnes per year. Doubling nuclear power capacity would thus remove over a quarter of the CO2 emissions from electricity genration
Which way should future energy policies push those figures?
What are the opportunities and limitations on solar and wind energy for grid-connected electricity generation?
Is salvation to be found in recourse to renewable energy sources (beyond hydro in very few countries)? There are those who appear to think so.
Personally I agree that on ethical grounds alone we should make the most of these, but no amount of research will make the sun shine longer or harder, nor command the wind to blow when most needed.
In the light of these obvious intrinsic reasons what is the limit to the possible contribution of renewables to (or in substitution for ) the electricity grids of increasingly urbanised countries?
If one ignored the cost per kilowatt-hour supplied, to what extent might renewables conceivably replace coal or nuclear electricity?
According the ESAA and several authoritative overseas estimeates the limit is probably about 20% of the total electricity, with some very generous economic, technical and environmental assumptions. Even then such capacity will require almost 100% back up from conventional sources.
So, how can wind and solar best be applied as complementary to coal and nuclear?
Nuclear energy is a fascinating subject which can well reward study!
My children's and their children's lifestyle and welfare will be significantly determined by the degree of ready access to energy resources.
Certainly, aspects of our present use of energy are wasteful.
But what would be the implications of doing without nuclear energy to meet the needs and expanding expectations of many people today and in the next century across the globe? Over two billion people do not yet have access to any form of electricity. That is a big challenge.
No energy conversion technology producing electricity is without risks or environmental effect.
So, what energy technologies are most benign and abundant for producing electricity on a large scale as nuclear power? What are most sustainable?
See other material on this Web site for further information and references.
From 1988-93 he was Manager, Education and Environment with CRA Corporate Service. He organised the CRA-ASTA Science Teachers' Fellowships for many years and in 1992 he received an ASTA Distinguished Service award.
His particular interests range from the technical to the ethical and theological aspects of mineral resources and their use, especially nuclear power. His most recent book is Responsible Dominion, a Christian approach to Sustainable Development, Regent College Press 2006, focusing on resource and environmental issues.
Since 2001 he has also been Director of Public Communications for the World Nuclear Association in London.
Australian Uranium Association Ltd
A.B.N. 30 005 503 828
GPO Box 1649, Melbourne 3001, Australia
phone (03) 8616 0440
fax (03) 8616 0441
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