A couple of other sources on nuclear options. http://www.gen-4.org/
http://thoriumenergy.blogspot.com/2009/04/thorium-molten-salt-reactor-launching.html I understand that gen 3 reactors utilise about 3% of the energy content of their uranium fuel source - leaving behind a radiation legacy for hundreds of thousands of years. Gen 4 reactors are 98% efficient, can use a variety of fuel sources including recycled gen 1, 2 and 3 waste, recycled weapons plutonium and thorium - so really it is a multiple fuel platform rahter than limited to thorium. The waste is safe enough after a couple of hundred years and can be made proliferation resistant. I should perhaps have called it a high temperature reactor rather than confuse the issue (with conventional breeder reactors) by calling it a fast neutron reactor. The low pressure reactors do not require expensive containment structures - so should be a lot cheaper. They are designed to be 'walk away' facilities using passive safety features - walk away and they cool down not melt down. There is no need for multiply redundant and expensive cooling systems. They are designed to be modular - modules can be manufactured in a factory and transported anywhere. They are operated at high temperatures facilitating hydrogen production (which can be used directly or converted to liquid fuels) from hydrolysis of water. Commercial 4th generation nuclear reactors are some 20 years off still but there are many places in the world where 3rd gen reactors are cost effective. Why not utilise existing technology in the meantime, generate the start up materials for rapid deployment and deploy the next gen technology ASAP. I have long argued that Australia needs to get heavily into the processing, reprocessing and storage of nuclear materials - for all sorts of reasoins. How can we supply nuclear mterials and morally not? We could continue burning coal locally for a while, offett all our emmissions and then some and make a profit. One of the potentially useful features of the newer technology is that it is modular and can be scaled up or down as required. They could be used, for instance, to replace conventional furnaces in existing coal powered generators. They could be used in situations in the developing world where a GigaWatt plant is overkill. You misunderstand me - while there may be population constraints at any one time the human species can move the goalposts with technology. The limit to growth is human ingenuity and I believe that is true yesterday, tomorrow, this century and, with a little flight of fancy, for the unlimited human destiny over the next 5 billion years amongst the stars. As we all know – there is no limit to either human ingenuity or human stupidity. ‘Heat Pollution. Over the next millennium and for the rest of human history, earth's major environmental problem will be warming due not to greenhouse gases but rather to increased waste heat from non-solar energy (initially petrochemical, but then fusion). The problem emerges when a world population in the high tens or low hundreds of billions all enjoy an energy budget equivalent to the industrialized West in 2000. All the waste heat from all the energy uses adds up, and the laws of thermodynamics guarantee that energy use always creates heat exhaust. Heat pollution will have to be managed to prevent a runaway greenhouse effect like on Venus.’ Source: http://humanknowledge.net/ Threadbare scientific justification for wild scenarios? Back of the envelope calculations for a system that not even the latest supercomputers can handle? (Researchers are calling for 1000 times current computing power just to handle cloud dynamics.) Give me a break. Several other possible disasters this century? There are a lot of people out there who need therapy. Not just an hour a week on a couch but a team of highly trained specialists working around the clock (joke). Inventing problems is too depressing - solving problems is a better option. Most people have given up even listening to environmental Cassandras. There is no possibility that the human population will reach even 10 billion. Current long range projections show population peaking in the middle of this century at about 9 billion. There is one way to reduce this number – accelerated global economic development. http://www.un.org/esa/population/publications/longrange2/WorldPop2300final.pdf Economies are a human construct. They are also a complex system in the terms of dynamically complex systems theory. They seem to need to grow to be minimally stable (no one ever claimed that capitalism is perfect). Heavy handed government intervention in global economies has very significant risks for us all as we have seen time and time again. However, if production is sustainable - there is theoretically no need to limit economic growth - and absolutely not as yet I believe even if systems are not yet sustainable. There is a great human need for continued development over this century. We simply need to engineer greener systems. Over the next millennium – we will need to start moving off planet because populations either grow or decline. (Populations are dynamic and complex.) Perhaps using instantaneous quantum teleportation for FTL travel? Quantum teleportation is an actual working technology based on quantum entanglement - though not of course workable for human star travel - yet. (Please - this latter is just a fun idea and I don't need to enter into a debate.) On Dec 29, 6:48 am, Phil Hays <[email protected]> wrote: > On Mon, 2009-12-28 at 10:25 -0800, Phil Hays wrote: > > Yea, I'm talking to myself. > > > BTW: A thorium fueled fast neutron reactor seems to me to be a very very > > odd choice. Thorium, unlike uranium, doesn't need fast neutrons to have > > a breeding ratio greater than one in a reactor. Both light water cooled > > and heavy water cooled reactors have been operated with thorium fuel > > rods, and have been shown to produce more fuel (U233) than consumed. > > Fast neutron reactors are more complex and expensive, but have the > > advantage of being able to breed more fuel (plutonium) from uranium > > (U238) than they consume (plutonium and U235). Why used a more expensive > > and complex reactor with the advantage of being able to breed fuel from > > uranium to breed fuel from thorium when cheaper and more reliable > > reactors can do that? I don't understand at all. Now, my interest in > > nuclear power comes from the fact that it seem to be a requirement to > > solve the global warming issue. I'm no expert on the details of nuclear > > power, so perhaps someone can point me to a discussion explaining this > > choice. > > Some quality time with Google let me find an answer to my question. > > Light water thorium breeder reactors have breeding ratios only a little > over 1. The Shippingport reactor, for example, ran at a breeding ratio > 1.01. As such it would require reprocessing to operate. Heavy water > thorium breeder reactors are somewhat better, and can operate with only > thorium fuel after startup, allowing reprocessing to be delayed for > decades or even centuries to allow for most of the very radioactive > elements to decay. Thorium breeders of any sort need to be fueled during > startup with a mix of thorium and either enriched uranium or plutonium. > For India, with little uranium resources and having had strict limits on > importing uranium, and with massive thorium resources, this poses a > startup problem for thorium based nuclear power. So India has designed > and is constructing fast neutron breeder reactors mostly fueled with > thorium to produce plutonium from India's very limited uranium to more > quickly start the thorium fueled power cycle. Such fast neutron reactors > would be not needed, or even useful in a steady state, or with the > abundant and cheap enriched uranium outside India. The limits on > importing uranium were imposed to limit/punish Indian nuclear weapon > production. > > Longer term, limits on uranium might be probably counterproductive. To > reduce the risk of U233 produced by a thorium breeder reactor being used > for nuclear weapons, the fuel mix could include some depleted or natural > uranium, which can't be chemically separated from the U233, but could > only be separated by isotopic enrichment. The reprocessed fuel from a > thorium only breeder reactor would be more usable for nuclear weapons > than reprocessed fuel from a thorium/uranium fueled breeder reactor. > > -- > Phil Hays <[email protected]> -- You received this message because you are subscribed to the Google Groups Global Change ("globalchange") newsgroup. Global Change is a public, moderated venue for discussion of science, technology, economics and policy dimensions of global environmental change. Posts will be admitted to the list if and only if any moderator finds the submission to be constructive and/or interesting, on topic, and not gratuitously rude. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/globalchange
