The LFTR in the American Scientist

The LFTR story has now been told for the July-August Issue of the American Scientist by Robert Hargraves and Ralph Moir. The American Scientist account tracks closely with the views offered by Nuclear Green. Of course, the LFTR community is collegiate, and both Hargraves and Moir have contributed important ideas to us. The Hargraves-Moir media presentation which Nuclear Green Linked to yesterday covers much of the same material found in the American Scientist article.

The article recounts the early history of the Molten Salt Reactor and Alvin Weinberg's contributions to it. The authors state

Knowing what we now know about climate change, peak oil, Three Mile Island, Chernobyl, and the Deepwater Horizon oil well gushing in the Gulf of Mexico in the summer of 2010, what if we could have taken a dif- ferent energy path? Many feel that there is good reason to wish that the liquid-fuel MSRE had been allowed to mature. An increasingly popular vision of the future sees liquid-fuel reactors playing a central role in the energy economy, utilizing relatively abundant thorium instead of uranium, mass producible, free of carbon emis- sions, inherently safe and generating a trifling amount of waste.

Dr. Hargrave and Dr. Moir lay out the advantages of the MSR/LFTR approach,

Liquid fuel thorium reactors offer an array of advantages in design, opera- tion, safety, waste management, cost and proliferation resistance over the traditional configuration of nuclear plants. Individually, the advantages are intriguing. Collectively they are compelling.

And indeed they are as the writers explain,

In solid fuel rods, fission products are trapped in the structural lattice of the fuel material. In liquid fuel, reac- tion products can be relatively easily removed. For example, the gaseous fission poison xenon is easy to remove because it bubbles out of solution as the fuel salt is pumped. Separation of materials by this mechanism is central to the main feature of thorium power, . . .

Other fission products such as molybdenum, neodymium and tech- netium can be easily removed from liquid fuel by fluorination or plating techniques, greatly prolonging the vi- ability and efficiency of the liquid fuel.

They note the potential of LFTRs (and indeed other types of Molten Salt Reactors) for solving the problem of nuclear waste. They note,

It has always been the dream of reactor designers to produce plants with inherent safety—reactor assembly, . . . The LFTR design appears, in its present state of research and design, to possess an extremely high degree of inherent safety. . . .

A signature safety feature of the LFTR design is that the coolant—liquid fluoride salt—is not under pressure. The fluoride salt does not boil below 1400 degrees Celsius. Neutral pressure reduces the cost and the scale of LFTR plant construction by reducing the scale of the containment requirements, because it obviates the need to contain a pressure explosion. Disruption in a transport line would result in a leak, not an explosion, which would be cap- tured in a noncritical configuration in a catch basin, where it would passively cool and harden.

One of the more amazing features of molten salt reactors is related to a safety feature, their negative temperature coef-ficient of reactivity, as Hargraves and Moir explain,

In the LFTR, thermal expansion of the liquid fuel and the moderator vessel containing it reduces the reactiv- ity of the core. This response permits the desirable property of load following— under conditions of changing electricity demand (load), the reactor requires no intervention to respond with automatic increases or decreases in power production.

The potential MSR/LFTR cost advantages are discussed. The factory based mass production of small (about 100 MWe) LFTRs is mentioned, as is the usefulness of LFTRs in providing developing nations energy at very reasonable costs.

Given the diminished scale of LFTRs, it seems reasonable to project that reactors of 100 megawatts can be factory produced for a cost of around $200 million. Boeing, producing one $200 million airplane per day, could be a model for LFTR production.

and the coal2nuclear via LFTRs idea is reported.

One potential role for mass-pro- duced LFTR plants could be repla ing the power generation components of existing fossil-fuel fired plants, while integrating with the existing electrical-distribution infrastructure already wired to those sites. The savings from adapting existing infrastructure could be very large indeed.

All of this, will of course be very familiar to Nuclear Green readers.

In short the Hsrgraves-Moir American Scientist article is an excellent introduction to MSR/LFTR technology, and the LFTR paradigm as developed by the Energy from Thorium Open Science community.

Aim High

I recently mentioned professor Robert Hargraves presentation "Aim High". Aim high presents a vision that Kirk Sorensen and I share with many other people. We believe that world energy problems can be solved through the use a revolutionary nuclear technology, the Liquid Fluoride Thorium Reactor. I have known about this for a long time because my father was in on the ground floor of the development of the idea. (No I am not going to make any money from this.) The LFTR uses far less fuel that conventional reactors, can be built in factories, produces almost no nuclear waste, and can produce all of the energy we need. In addition LFTRs are less expensive than conventional nuclear power plants.

Here is a video of Dr. Robert Hargraves presentation "Aim High".

Dr. Robert Hargraves is a very bright fellow. He thought of some of my best ideas before I did. I did not steal Dr. Hargraves ideas, but I may have borrowed a few. I think that I actually developed my ideas for a factory build, small LFTR before I read Dr. Hargraves Blog. There are actually a few variations between Dr. Hargraves visions and mine, but that is beside the point. Both of us think along similar lines about the advantages of small reactors and how to build them quickly, in expensively and in large numbers. Our thinking is directed to slightly different technologies. Dr. Harvraves offers us some interesting insights into technological advances since the 1970's that can contribute of PBR and for that matter LFTR technology. Anyone who is interested in Reactor safety, ought to read Dr. Hargraves discussion of PBR passive safety.

Of course not all of the ideas Dr. Hargraves presents are original with him. Some of them come from a little school called MIT. The MIT Pebble Bed Reactor web site is well worth the time the nuclear curious might spend poking around it. Clearly the MIT work on industrial production of PBRs is a starting point for anyone who wants to design a system of large scale LFTR production.

Looking at the MIT site raised some issues. For example, MIT cost studies based on 1992 data found that a 1100 MWs modular PBR generating facility would cost $2296 1992 dollars over night costs. This was not the sort of savings I would hope for. However, MIT did not engage in the sort of full court press model of reactor cost savings I advocate. Jim Holm proposed reusing old coal fired stem plants as sites for new nuclear facilities. MIT did not consider the economic advantages of Holm plan. Old power plant sites would be well suited to a modular approach, and would enable power production to closely approximate local grid capacity.. One way LFTRs would lower nuclear costs would be the very reduced need for nuclear waste handling and storage facilities. The 100 fold reduction of the nuclear waste problem with LFTR in one of the most significant advantages of that technology over the PBR approach, PBR waste would not only be far more expensive to store, but also far more expensive to reprocess, than LFTR waste would. But then one of the reasons why ORNL chose to examine the liquid fuel approach was the lower cost of fuel reprocessing that a liquid fuel would facilitate.

MIT researchers acknowledged the capital cost advantages of adding more reactors to a modular facility as demand increases, rather than building over capacity, in order to achieve economies of scale in a reactor. Hence an owner might buy 5 100 MWe PRR or LFTR units, thus lowering initial costs. Each unit can be in place ands producing electricity far sooner than a large reactor would be. Thus interest carrying costs would be substantially reduced.

Lowering the cost of electrical generating technology is going to be a major future concern. Research should be directed to lowering nuclear cost. Unfortunately the conventional method for lowering reactor costs is the economies of scale approach. This approach makes far less efficient use of labor that the factory production or factory produced modules approach. Even with reactors like the AP-1000, a conventional reactor designed to be built using factory produced modules, the rate of module production would be far lower, thus the savings entailed by serial production of modules will be far from fully realized. Clearly much more research on lowering nuclear cost should be conducted. Research needs to be directed to developing cost lowering stratigies, and to the potential for cost saving with Generation 4 technology.

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If there is to be a major LFTR effort, where should it take place? I would argue that ORNL would be the ideal place, because of its tradition of Liquid core reactors, even though ORNL stopped MSR research over a generation ago. Were INL to take responsibility for LFTR research, it would require new facilities and a new staff. INL has entirely devoted itself to solid core reactors, thus would have no advantage over ORNL as far as institutional memory is concerned. In fact INL long term commitment to solid core reactors would serve as a disadvantage as Lab staff struggled to understand the challenges of liquid core reactors.

The old K-25 site outside Oak Ridge could serve as the location of a LFTR factory. Ready access to Milton Hill Lake would allow whole reactor assemblies to be moved to destinations by barge.