Integral Fast Reactor: The Safe Nuclear Fission Reactor?

Shaken by the Three Mile Island, Chernobyl, and more recently, the Fukushima Nuclear Power Plant disaster, will the IFR fulfill the nuclear energy industry’s needs for a safe nuclear fission power plant? 

By: Ringo Bones 

For over 50 years, the world has been waiting for the dream of the practical nuclear fusion energy to be realized – but engineers at Argonne National Laboratory had already tested the supposedly safe next generation of that old and much-abused standby – the nuclear fission reactor. Since 1991, nuclear engineers at Argonne had not only tested but had built a kind of nuclear fission reactor that not only is inherently safe but also consumes its own dangerous radioactive wastes – including dangerous radioactive wastes from other older commercial fission nuclear power plants. 

The Argonne nuclear engineers’ design is dubbed the Integral Fast Reactor or IFR that uses high-energy or “fast” neutrons to trigger the nuclear fission chain reaction. In contrast, conventional light-water reactors which are currently used by over 99% of the global nuclear fission power plant industry typically slow their neutrons down with a “moderator” like graphite rods or heavy water. And given that fast neutrons can cause many more types of elements to undergo fission, the IFR is not limited to using uranium and plutonium that conventional commercial nuclear fission reactors use as fuel. 

The IFR can also use the highly radioactive elements with half-lives of tens of thousands or even a few million years that are by-products of uranium and plutonium fission that are deemed as “radioactive wastes” as its own fuel. By separating the long-lived radioactive isotopes out of the waste stream, nuclear power plant operators using the IFR type nuclear fission reactor will finally eliminate the problem of having a huge inventory of radioactive wastes that requires hundreds of thousands, and like neptunium-237, even a few million years of containment. And unlike the more familiar breeder-type nuclear fission reactors still operating in Europe and Japan, the IFR can “burn” plutonium rather than producing it. It thus precludes the possibility that a cache of nuclear weapons-grade fuel might fall into the hands of rogue states and terrorist bomb makers – lessening the headache of the International Atomic Energy Commission when it comes to “auditing” potential nuclear weapons-grade materials used by most typical commercial nuclear fission power plants. 

The other great advantage of the IFR, according to its designers at Argonne, is a safety system that makes it virtually resistant against those catastrophic loss-of-coolant accidents that crippled the Three Mile Island, Chernobyl, and more recently the Fukushima Nuclear Power Plant during the Japanese tsunami of March 11, 2011. The IFR’s fuel assembly is designed in such a way that it would actually expand if it started to get too hot. This thermal expansion would allow more neutrons to escape from the reactor core and since it is the neutrons that trigger fission, the neutron leakage would slow the chain reaction and eventually bring it to a halt – before a disastrous core meltdown could occur. And given the lack of progress in the commercial applications of nuclear fusion, the IFR seems to be the only near-term technology currently available that can provide a huge energy source while addressing global warming and environmental concerns over excessive carbon dioxide and other greenhouse gas emissions in commercial power generation.