Contestant two: IMSR – the Integral Molten Salt Reactor
The Integral Molten Salt Reactor is an MSR that makes a point of taking the KISS principle seriously: Keep It Simple Stupid. Its proponent, the Canadian nuclear researcher and engineer David LeBlanc, does not claim that IMSR is the Ferrari of molten salt reactors.
But he does claim it is by far the most doable of the concepts so far. (The next contestant presented on this site, the German Dual Fluid Reactor had not yet been introduced at the time LeBlanc made this claim.) In his presentation in May 2013 for the Thorium Energy Alliance Conference, LeBlanc pointed out that R&D costs for new nuclear technology can be huge. “Proving designs to regulators can be enormously expensive.” In his remarks, he did not directly point at LFTR, but many experts believe that the inline reprocessing conceived for LFTR will be a major obstacle.
LeBlanc also points out he is not opposed to LFTR, and believes it is a design worth investigating. But if we want to have a start with molten salt reactors, LFTR is not the one to start with.
Also, in the view of LeBlanc, the use of Thorium is not essential to the move towards the development of commercial molten salt reactors. Hence is adagium: ‘Come for the Thorium, stay for the reactor.’
Like the LFTR, the IMSR goes straight back to the research in the 60s and 70s in Oak Ridge, but adds the outcomes of more recent research done in Oak Ridge that have resulted in concepts for small, modular reactors, especially the SMATHR, which is a reactor that uses liquid salt for cooling and solid fuel. LeBlanc Embraces some of the very smart design features of the SMATHR, but prefers to combine these with liquid nuclear fuel.
In his presentation at the TEAC conference in May 2013 LeBlanc pointed out that the issue at stake is not the choice for thorium. The issue is the choice for the technology of molten salt reactors.
That being said, there is still a wide variety of reactor designs to choose from, each with its specific benefits and challenges. For now, according to LeBlanc, the best idea is not to aim for the technology that may be the ultimate in terms of efficiency – but that is facing huge challenges in getting accepted by regulation authorities.
LeBlanc’s IMSR is a true molten salt reactor. It uses uranium, rather than thorium, although it will be able to use thorium as well.
It can also be fueled by transuranics presently known as nuclear waste. Other than the LFTR, the IMSR is a burner, not a breeder. While most researchers focus on breeders (which create their own fuel out of isotopes not readily fissionable), LeBlanc has weighty reasons for his present focus on burners. First, he is convinced that the R&D costs, as well as the operational costs for continuous salt processing – a hallmark of the LFTR – will be much higher than most assume.
Also, pure Th-233 breeders, read LFTR, involve using highly enriched uranium, which, according to many, is a non-starter on proliferation grounds. And finally, still according to LeBlanc, a burner has negligible fuel costs, has assured and abundant resources – notably low enriched uranium – is much simpler in design, can be realized with lower R&D-costs and lower capital costs.
Compared to present LWR’s, IMSR specs are quite convincing. It uses 1/6 of the fuel used by an LWR. It employs a 30-year once-through cycle while a yearly supply of a small amount of LEU suffices. After its 30 years cycle, the accumulated transuranics can be recycled into the next batch, the remaining uranium can be recovered and only a very small fraction of the core needs to be stored for about 300 years. After this, less radiotoxicity exists in the world than before – a claim unequalled by any other reactor.
What all of this adds up to is a price per kWh that is lower than for coal. For investors, it is noteworthy that LeBlanc plans add up to a simple business case. In an interview with asme.org he is quoted as having said “There has been no opportunity like this since [John D.] Rockefeller gobbled up the entire oil industry in the late 1800s.”
And LeBlanc means business. He filed broad MSR-patents for the U.S. in May 2008, and international patents in November 2009. So where can we find the investors desk? Alas, LeBlanc seems to have had a lucky hand here, he may not need investors anymore. Over the last years, he has been teaming up with Canadian Oil Sands developers, who, LeBlanc notes, ‘could fund the entire IMSR development from their pocket change’. Plus, these investors are used to having 15 year development horizons.
Why would oil sand developers be interested in the IMSR? For a simple reason: heat. The oil is only released when huge amounts of superheated steam are applied to the unwilling sands. IMSR’s can supply such heat in sufficient amounts cheaply.
For LeBlanc, this eliminates the need to simultaneously develop a Brayton cycle electric turbine: a very smart move for a start-up that is already loaded with technical challenges. Once the IMSR has proven its case, electricity companies will line up to fund the development of Brayton turbines. And LeBlanc and the by then nuclear oil sand barons will only have to determine the price of their convenient 20, 100 and 300MWe IMSR modules.
The illustration underlines LeBlancs claims. It may even tell more than LeBlanc did in his presentation in May 2013. In the middle, we see the SMATHR, of which LeBlanc used some design principles for his IMSR, but which he considers to be too much of a compromise to be a serious contestant for a true MSR. To the right, we see two innovative designs for what the MSR-movement considers as old hat technology. These are modular versions of Light Water Reactors, the conventional technology of the overwhelming majority of existing nuclear power plants. Presented are a 540MWt/160MWe module Babcock and Wilcox and a 145MWt/45 MWe NuScale module. Note the difference in ratio of thermal and electric efficiency between these reactors and the IMSR’s on the left. The LWR’s convert about a third of the energy produces into electric power. The bigger one of the two IMSR’s produces 650MWt/300MWe, which means it converts almost half of the energy into electricity – the 50% higher efficiency is due to the higher temperature, that allows the use of a more efficient type of turbine. The higher temperature also means the IMSR, and all MSR’s for that matter, are useful as a source of industrial heat.
Internet Source: http://www.daretothink.org/msr-development-programms/imsr/
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