Transcript Slide 1
Nuclear Energy and Waste By: David Long (0675325); Chris Marcyniuk (0569880); Adam Foster (0676006) IMS3 Sustainability Module, March 2009 SustainableEngineering@Edinburgh Nuclear Energy – What is it? •Harnessing the energy output from nuclear fission Cut down Carbon Emissions •Climate Change (Scotland) Bill – aims to cut greenhouse gas emissions in Scotland by 80% by 2050. (UK aim is 60%) •Oil, gas, coal – main provider. Need alternatives. Alternative Energy Sources •Biomass, hydro, solar, wind, wave, NUCLEAR References: Kaku, M., Trainer, J. 1982. Nuclear Power: Both Sides Kemp, R. 1992. The Politics of Radioactive Waste Disposal http://www.world-nuclear.org http://www.globalwarmingart.com Waste •Spent fuel rods that can not be reprocessed into usable fuel have to be disposed of. •This material is still highly radioactive and must be handled with as much care as new fuel rods. The half life times for most commercially used isotopes are usually in excess of 105 years. •Fuel reprocessing is still a debatable subject; at present Uranium prices are not cheap enough to make reprocessing worthwhile so other disposal is needed. •The general consensus is for long term deep storage in stable geologic formations up to 1000 m below ground in hard rock that will remain stable for tens of thousands of years. Public Opinion - Divided •Nuclear Power grew worldwide 750% in 70’s, 140% in 80’s but only 8% in 90’s •Disasters –Three Mile Island (1979), Chernobyl (1986) •For nuclear energy to become a sustainable source of power new ways •Will the disasters happen again? must be found to reduce the amount of waste produced and reuse what is. •Nuclear Proliferation •Nuclear Waste Sites •Long lead times and huge expense to build facility. It The Nuclear Fuel Cycle begins takes 10-15 years to come online and about $5 billion to when uranium is mined, build – futile attempt in race against global warming? enriched, and manufactured into •Energy produced by one nuclear reactor is around 1,000 nuclear fuel, (1) which is megawatts. The world’s largest wind farm, currently delivered to a nuclear power under construction, will provide 500 megawatts, costing plant. After usage in the power $1.8 billion. plant, the spent fuel is delivered •As of 2007, nuclear power accounts for about 17% of to a reprocessing plant (2) or to the world’s electricity production. a final repository (3) for geological disposition. In reprocessing 95% of spent fuel can be recycled to be returned to usage in a power plant (4). Conclusion: •Mining and enriching Uranium uses large amounts of energy and is detrimental to the environment. •Currently the vast majority of reactors are fission reactors which have to be refuelled at the end of the fuel rod cycle. The waste produced is highly radioactive and will remain an issue for thousands of years. •In order for nuclear energy to become fully sustainable, new technologies will have to be used to fully process any waste or fast breeder reactors developed to minimise the need to mine uranium and reduce the amount of waste produced. •In a social context, nuclear energy is seen as a dangerous technology. This misconception suggests that the construction of new power stations would be met with widespread opposition from the general public. In order to ensure the success of nuclear power, public opinion would need to be changed. •Economically, nuclear energy is expensive to start up. In Britain, a large scale nuclear electricity program would have to be financially backed by the government. This would take many years to set up and is a stumbling block to widespread nuclear power production. Future Current research identifies two possible sustainable advances in nuclear technology: Fast Breeder Reactor •If more fuel is created than is used, then the reactor is known as a Fast Breeder Reactor •In Fast Reactors, the neutrons released through fission are not cooled down •Although these high energy neutrons are not as efficient at causing fission, they can join with an isotope of uranium, U238, to create plutonium, U239, which can be reused as fuel by the reactor after it is reprocessed •Compared to reactor cores in current use, the system is uneconomical, and the reprocessing of plutonium creates a lot of nuclear waste. The technology to make Fast Breeder Reactors sustainable is about 20 years away, but it will be needed as the world supply of uranium is limited Nuclear Fusion •Nuclear fusion is the process by which multiple likecharged atomic nuclei join together to form a heavier nucleus. •It is accompanied by the release or absorption of energy. This energy could be harnessed and used to produce electricity. •Technology could be 50 + years away. •Provide much more energy for a given weight of fuel than any technology currently in use. Experts say it could provide the world’s energy for millions of years.