Wednesday, September 17, 2008

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.


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.

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