Saturday, November 1, 2008

The argument for factory assembly of the LFTR

David Walters and I have a standing disagreement about factory production. of LFTRs. My case study was based on the auto industry which some early manufacturers built assembly kits and then when they received an order they dispatched a kit and an assembly team to the customer. The cars were assembled near the customer's home. This is still the prevailing system of reactor manufacture. Eventually the car companies built all of their cars in factories but with an assembly team approach. People would typically have a number of assembly assignments on each car. The car was built at a fixed location and the workers flowed around the car as they manufactured it. When Henry Ford set up his assembly line workers had only one assignment, and one work station. In the Ford factory the cars flowed from worker to worker. Note that all of the Ford assembly was still hand assembly. The great advantage of the Ford assembly line was in the greater devision of labor and the more efficient use of labor. It was the division of labor and the flow of manufactured objects from worker to worker o the assembly line that revolutionized auto industry productivity.

The effect of the division of labor on worker productivity is the subject of a marvelous passage from Adam Smith's "Wealth of Nations".
To take an example, therefore, from a very trifling manufacture; but one in which the division of labour has been very often taken notice of, the trade of the pin-maker; a workman not educated to this business (which the division of labour has rendered a distinct trade), nor acquainted with the use of the machinery employed in it (to the invention of which the same division of labour has probably given occasion), could scarce, perhaps, with his utmost industry, make one pin in a day, and certainly could not make twenty. But in the way in which this business is now carried on, not only the whole work is a peculiar trade, but it is divided into a number of branches, of which the greater part are likewise peculiar trades. One man draws out the wire, another straights it, a third cuts it, a fourth points it, a fifth grinds it at the top for receiving the head; to make the head requires two or three distinct operations; to put it on, is a peculiar business, to whiten the pins is another; it is even a trade by itself to put them into the paper; and the important business of making a pin is, in this manner, divided into about eighteen distinct operations, which, in some manufactories, are all performed by distinct hands, though in others the same man will sometimes perform two or three of them. I have seen a small manufactory of this kind where ten men only were employed, and where some of them consequently performed two or three distinct operations. But though they were very poor, and therefore but indifferently accommodated with the necessary machinery, they could, when they exerted themselves, make among them about twelve pounds of pins in a day. There are in a pound upwards of four thousand pins of a middling size. Those ten persons, therefore, could make among them upwards of forty-eight thousand pins in a day. Each person, therefore, making a tenth part of forty-eight thousand pins, might be considered as making four thousand eight hundred pins in a day. But if they had all wrought separately and independently, and without any of them having been educated to this peculiar business, they certainly could not each of them have made twenty, perhaps not one pin in a day; that is, certainly, not the two hundred and fortieth, perhaps not the four thousand eight hundredth part of what they are at present capable of performing, in consequence of a proper division and combination of their different operations.

I know that it will pain David no end to read Adam Smith rather than Karl Marx, but it will do him no end of good in the end.

Smith understood that the organization of labor and the assignment of simple tasks that was to key to labor productivity. Westinghouse estimates that it will take between sixteen to twenty million man hours of labor tbuild an AP-1000. It becomes a monumental task just to organize the flow of work on the construction site. Teams of managers will inevitably be involved in the relaying of information between project engineers, and workers. Workers are highly skilled, and flow from project to project on the construction site. The organization of the work is constantly in danger of breakdown, and the learning curve progresses slowly, because it takes years to manufacture one reactor.

If reactors are manufactured in factories then they must be transportable. Hence must be built in small transportable units. LFTRs need not be horrendously complex. Controls are largely passive. hence there are no control rods. There is no complex system of pipes inside the reactor. Conditions - reactivity and heat levels - inside the core of a LWR are far from uniform, hence the need instrumentation and localized control. Conditions in the LFTR core are homogeneous. There is no need for refined instrumentation and refined control systems. LWRs have complex pipe systems, that are required inorder to bring coolant water to every part of the reactor. In addition to the primary coolant system, there are complex secondary systems and an emergancy cooling system.

We thus have a much simpler assembly task for our Liquid Fluorid Thorium Reactor (LFTR) factory workers, compared with the AP-1000 construction crew. The next question is how many LFTRs will we need? The DOE estimates that in order to provide for estimated peak demand in 2050, the United States will need something like 1800 GWs of electrical generating capacity. Perhaps 300 GWs will be LWR base load reactors. The rest is at the moment an open question, but 15,000 factory built LFTRs are not out of the question. This number may be conservative, because we may be expanding our generating capacity to generate electricity for transportation, for space heating that is now acomplished by natural gas. There are other markets, for example process heat. LFTRs could be used to power ships. There is a potential for a large export market. Consider that even with proliferation restraints, the export market could be 10 times larger than in the United States.

A highly automated assembly line might make sense.

Workers on a modern auto assembly line


Rod Adams said...


Can you provide some kind of dimensional quantities for a shielded LFTR?

What is the pumping system like that moves the heated molten salts from the reactor to the heat exchanger?

How much piping will there need to be in the heat exchanger?

Will there be a need for a lot of welding or just a little?

Rod Adams

Charles Barton said...

Rod. I would refer you to a couple of sources in "Energy from Thorium". First, Kirk Sorensen participated in a reactor design project involving a mobile 100 MW LFTR. The discussion of the design can be found here: In the EfT Discussion Form: Board index » Liquid-Fluoride Reactors » Mobile/Submersible Reactors.
Title: A Small, Mobile, Molten-Salt Reactor for Remote Power

I hope you find the paper and presentation Kirk attached helpful.

I would also recommend David LeBlanc's "The Modified Geometry 2 Fluid Molten Salt Breeder"
(, in addition to David's elaboration of his unusual design concept in the discussion form.

Secondly for more classic design concepts of large MSRs go to the EfT Document Repository and find:
ORNL-4541: 1971-06 (13.2M PDF)
Conceptual Design Study of a Single-Fluid Molten-Salt Breeder Reactor

ORNL-4528: 1970-08 (6.9M PDF)
Two-Fluid Molten-Salt Breeder Reactor Design Study

The former study was the basis of ORNL MSR research and development work in the early to mid 1970's, and is the starting point of recent French LFTR R&D. Ralph Moir also used it as a basis for his study of large MSR costs.


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