Much has been said in recent times about the US-India nuclear transfer agreement and the export of Australian uranium to India, even by yours truly. It is to be expected that we shall hear plenty more about this in future now that the government has formally agreed to the sale of uranium. My purpose here, however, is to focus very narrowly on one aspect of the issue that may have interesting implications and that is on India’s three-stage nuclear fuel cycle strategy and the role of the fast breeder reactor within it.
The fast breeder reactor is a special reactor type. Most reactors are called thermal reactors because they utilise slow neutrons to trigger nuclear fission. As the name would suggest fast breeders utilise fast neutrons. They also act as efficient breeders of fissionable material, especially plutonium. The idea behind the fast breeder is to produce more fissionable material than is consumed. For instance by bombarding a nucleus of uranium-238, that is natural uranium, one can breed plutonium-239 after two successive beta decays. Plutonium-239 is the isotope of plutonium generally used in nuclear weapons.
Nuclear fission that is unleashed by fast or high energy neutrons produces more new neutrons than that by way of thermal neutrons. Pu-239 with fast neutrons produces 2.9 neutrons per fission, the highest for the various fissile isotopes. If one were to surround the core of a fast reactor with a blanket of ordinary uranium the neutrons produced from the core could turn this material into more plutonium-239 by way of the above reaction again. By placing a very tight fit between the blanket and the core of a fast reactor comparatively few neutrons would be lost and over time thereby the amount of plutonium produced would exceed the amount consumed.
A similar process occurs in nuclear weapons where a tamper reflects neutrons back into the plutonium pit to increase the efficiency of fission or in boosted fission weapons where neutrons produced in the fusion of deuterium-tritium gas produces extra neutrons, although weapons do not of course breed plutonium.
The plutonium 239 used in a fast breeder reactor usually comes in the form of a Mixed Oxide Fuel, that is a mixture of plutonium oxide and uranium oxide typically with a 20:80 ratio between the two respectively. The most important point to consider from our perspective however is that any plutonium 239 present in a fast neutron reactor must be very highly concentrated, that is highly pure plutonium 239, in order to prevent the loss of neutrons.
Nuclear fuel cycles based on the fast breeder reactor concept have been the holy grail of the nuclear industry but have been dismal failures. But a few countries still are pursuing the dream such as Japan, France, China and India. It is revealing that in each case energy security is an important motivating factor, a fact of no small moment given the looming peak in oil production and the expansion of nuclear power.
The latter case is especially interesting for the fast breeder reactor is an integral part of India’s three-stage nuclear fuel cycle strategy. The three stages consist first, of utilising heavy water moderated reactors; second, fast breeder reactors; and third, thorium-based breeder reactors.
The idea with such thorium reactors is to use thorium to breed uranium-233, a fissionable isotope of uranium. The reason why India wants to achieve this penultimate stage in its fuel cycle strategy is of great import. It is recognised that India has small reserves of uranium but large reserves of thorium.
Implicit in the very concept of India’s three-stage nuclear fuel cycle strategy is recognition that India does not have enough reserves of uranium to both maintain fissile material production for nuclear weapons, if not expand such production, and significantly increase the amount of electricity generated by nuclear power stations to help fuel economic growth.
The emphasis on breeding fissile material by way of fast neutron reactors is also an acknowledgement that India’s uranium reserves imposes a strict upper bound on its civil and military nuclear programs.
It is often stated by supporters of government policy on uranium exports, for instance by Rory Medcalf writing in The Sydney Morning Herald that even exporting coal to India would free up Indian uranium reserves. Medcalf’s point is only of relevance as an example of how a pathetic and superficial understanding of the issues can enter public discourse even in so august a publication as the Herald.
As often stated elsewhere the US-India nuclear transfer accord will set the framework for Australian uranium exports to India. Under the 123 agreement that implements the accord India’s fast breeder reactor program will not be safeguarded. During negotiations this was a sticking point with Washington keen to subject India’s current fast breeders to safeguards. India held firm on its position and the United States has clearly relented. It is worth looking at some likely implications of this.
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