Moving Toward Marketable Generation IV Reactors

It is practical to design and build, practical Generation IV reactors today, but ones without all of the bells and whistles. It is becoming increasingly likely that a small Generation IV nuclear plant will find its way onto the grounds of a coal fired power plant near you soon.

There are two potential approaches to the development of commercially viable Generation IV type reactors. The first is to design and build commercially viable reactors that are viable using existing technology. This is a practical approach, because it would limit the Research & Development investment required to bring a product to market. On the other hand, by limiting product design to existing and tested technology, you are reasonably assured of bring a product to market within a reasonable period of time, with a reasonable budget, and at a somewhat predictable cost. In the case of Generation IV reactors, this would mean basing products initially on products that would be based on existing, tested technology. That is technology that had gone into prototypes. Generation IV reactor advocates point to two successful Generation IV prototypes, the ORNL MSRE, and the Argonne/Idaho National Laboratories EBR-II. Both prototypes were stable, highly safe reactors that pointed toward potentially successful future designs. Both were highly safe, and offered pathways to sustainable and safe nuclear energy.

The first objective of any commercial nuclear project is to make enough money from the sale of products. Money cannot be made before products are brought to market. Thus bring viable products to market at a price that will motivate buyers and will allow the business to make a profit, should be the highest priority of any new commercial reactor project. The fewer uncertainties, the fewer risks, the more likely a product can be brought to market within a reasonable period of time and at a competitive cost.

The Babcock & Wilcox mPower Reactor actually sets a benchmark for Generation IV reactors. Generation IV reactors will need to compete with the mPower and similar reactors both in capital costs and in operational and maintenance costs.

The ARC-100 reactor project in the main conforms to the to the practical approach. Its design tracks closely with the design of the Experimental Breeder Reactor-II as it evolved into an Integral Fast Reactor prototype. The ARC-100 will be a more powerful reactor than the EBR-11, but not by an problematic extent. Current thinking suggests that reactors capable of generating 100 MWe represent a convergence point between the maximum financial benefit of factory reactor production, and grid usefulness. Smaller reactors because they produce less electricity, may represent less attractive investments for utilities seeking to replace fossil fuel generation sources, while larger reactors may demand far more expensive field construction. Thus the ARC-100 with an electrical output of 100 MW, is size competitive with the 125 MW mPower Reactor. The challenge then would be to motivate they buyer with an attractive costs.

The flaw in the ARC-100 project at the moment is the announced intention to use a supercritical carbon dioxide closed Brayton cycle gas turbine in the electrical generation system. Thus we are confronted with a plan to use a technology that does not exist. The motive for this is the added efficiency and safety of the Brayton Cycle approach. The downside is that it makes the future of the project dependent on the successful of supercritical CO2 turbine development. A plan B should exist if the manufacture of the turbine is delayed. Plan B would rely on steam turbines for electrical output.

Many of the technical features of the ARC-100 are still unknown. However reportedly will enjoy a 20 span before refueling, thus in house fuel reprocessing, a major feature of the IFR approach is not on the table. This is just as well. There is no discussion of conversion rates, but the 20 refueling year figure suggests that they would probably be about 1 to 1.

The ARC-100 is likely to be a very simple reactor, which aside from its sodium cooling system would give its owners few reasons to worry. ARC-100 design features include underground an silo placement.

The potential rub for such a design would be decay heat dissipation in the event of an emergency shutdown. It would be possible to design a passive air cooling system for an underground reactor with natural air flow facilitated by a chimney effect. Yet concerns about a sodium fire might preclude that.

The underground setting will, however, probably answers the fears of the chicken littles who worry about terrorists attacks on reactors using Airbus-380 size aircraft.

Management and direction of the ARC-100 project leans heavily on National Laboratory management veterans, although investors are fairly well represented on the ARC Board of Directors. Manufacturing and construction engineering, conspicuous assets to the mPower project, are complete unknowns for the ARC-100 project. Perhaps an even more troubling sign is the broken links to any internal documentation on the ARC web page. A June 14 press release, no longer accessible on the ARC web site, states:

The ARC-100 reactor initiates a new model of nuclear power, based on factory fabrication of shippable modules for rapid site assembly that enables the prompt start of a revenue stream.

What ever doubts might be raised about the ARC-100 project, their heads are in the right place. Rapid assembly and a prompt start of a revenue stream would certainly please customers, if those features are combined with a competitive price. Realization of these three goals will not be easy.

I discussed the Fuji reactor project a couple of days ago. Fuji project press releases focuses less on customers' expectations and more on market size. The Fuji plan does not focus on manufacture, but it does discuss projected costs. Those projected costs are, if anything high, and suggest a lack of exploration of cost saving approaches. The reactor housing is above ground, an indication that the designer may not be aware of recent reactor housing discussions. The Fuji has had a 40 year long gestation period, as a reactor design, and draws heavily on the ORNL MSR heritage. The weakness of the Fuji design is that it does not take into account Kirk Seoensen's innovative use of the Open Science model on his blog Energy from Thorium which facilitated the ongoing discussion on LFTR and other MSR designs on Energy from Thorium, David Le Blance's brilliant innovation in Molten Salt Reactor core design, Edward Teller and Ralph Moir's advocacy of underground housing for Molten Salt Reactors, the emergence of the factory manufactured small reactor model, Jim Holm's coal2nuclear concept, as well as my own ongoing exploration of cost lowering approaches that could be applied to LFTR manufacture and deployment on Nuclear Green and Energy from Thorium. Taken all together, between 2006 and 2009 the old nuclear energy paradigm began to die, and a new thorium-LFTR paradigm began to take its place. That paradigm is a modified version of an earlier thorium paradigm which was developed in Oak Ridge during the 1960's and 70's. The Fuji project is rooted in the old rather than the new Thorium paradigm.

While the Fuji project as currently constituted is rooted in the old paradigm, its developers have come into contact with advocates of the new thorium paradigm. In addition at least two leaders of the thorium movement, Kirk Sorensen and David Le Blanc have made moves toward developing molten slat reactors. Significantly both have expressed interests in moving away from the thorium model in the short run, in order to facilitate practical designs that will can move from conception to production fairly quickly. Both appear to be thinking in terms of uranium rather than thorium fuel cycle Molten Salt Reactors. With such realism a rapid transition to commercial prototype and serial produced model becomes a possibility.

The emergence of even a single commercial MSR model on the market, provided it meets practical expectations, would be a great step forward for Molten Salt Nuclear Technology, no matter what fuel cycle is used. As with the ARC-100 the most important step is not to produced the most advanced reactor conceivable, but to produce on at a reasonable price, and with sufficient attractive features that it will interest customers. Product evolution will carry the design forward once a successful model is launched.