April 10, 2012

Submarine reactors - thorium technology? Proliferation still constant.

Should thorium reactors be replacing this enriched uranium submarine reactor? Click on diagram to enlarge this standard uranium reactor.
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jbmoore has spotted this article from DefenseNews November 16, 2009:
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"The recently passed fiscal 2010 U.S. National Defense Authorization act initially contained a mandate for the Department of Defense to study thorium, a radioactive metal found abundantly in the United States that could change the future of nuclear energy. The initial section called for the Secretary of Defense and the chairman of the Joint Chiefs of Staff to "jointly carry out a study on the use of thorium-liquid fueled nuclear reactors for naval power needs." Unfortunately, this section was absent from the final version of the bill. ...
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Thorium is a safer alternative for the U.S. Navy's nuclear-powered fleet that is more proliferation-proof than uranium, and also three times more abundant. It is not fissile on its own, but can be combined with a small amount of uranium to serve as a "feeder" material for a nuclear chain reaction.
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Thorium cycles do not generate usable plutonium as a byproduct, and they produce as little as half the nuclear waste uranium cycles do. For these reasons, thorium can help reduce the concerns about nuclear proliferation that are commonly associated with nuclear power...article in full..
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Comments
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Surely only America's adversaries (the Russians and Chinese) would wish thorium reactors on the US Navy.
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After 30 more years of further development thorium may be useful in land based reactors but at present starting with submarine reactors as testbeds for thorium possibilities seems a misapplication. Increasing use in power reactors on land would be a better start.
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Submarine reactors need to be miniature, light and uncomplicated enough to be adjustable by the crew at sea. Thorium, I believe, puts out a relatively low amount of radioactive "power' per pound compared to the 93% enriched uranium now used in US submarine reactors. With thorium reliance - subs would either be forced to slow down or carry a much larger, heavier, more complicated thorium reactor.
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Thorium is also a messy, substance which tends to make reactors shut down unexpectedly - not a good look under the waves. Thorium reactors generate more residue that needs cleaning out - hence more downtime for subs in port.
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While the article extols the lower proliferation advantages of thorium for the US Navy's nuclear carriers and subs reducing the proliferation risk seems almost a contradiction in terms. They all might carry nuclear weapons when the US goes to higher stages of defence alert. Furthermore all US SSBNs carry many nuclear warheads in peacetime. Temporary proliferation is often their job.
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Numerous US laws and policies, national security considerations and the NPT prevent export of US submarine reactors to other countries or nuclear weapons (except to the UK) . So US sub reactors, be they uranium or thorium dependent, or weapons would not be proliferated.
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On a tangential note, the US bans proliferation to all allies except the UK see 1958 US–UK Mutual Defence Agreement ). Australia may one day be seeking nuclear propulsion assistance elsewhere - from France - as Brazil is already doing. And for weapons - French and Israeli assistance worked for South Africa.
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Pete