Ralph Moir Interview: Part II

Ralph Moir's Post-retirement Interest in the Molten Salt Reactor

After your retirement you seem to have shifted your focus from fusion/fission hybrids toward more conventional molten salt reactors. In addition to the paper you wrote with Edward Teller, you appear to have some involvement with the Fuji Molten Salt Reactor Project.
1. Can you tell us why you shifted your interest from fission/fusion hybrids to more conventional Molten Salt Reactors?

My job at Lawrence Livermore National Laboratory involved studying and designing fusion/fission hybrid reactors. I lead the effort of many terrific researchers including those at other labs: ORNL, ANL, INL, PPPL and industries: Westinghouse, GE, GA, Bectel. During this time I became increasingly more familiar with all the fission reactor concepts. My favorite technology for fuel production was the use of molten salt pumped through the blanket surrounding the fusion reactor.

My favorite fission reactor was the molten salt reactor whose program was terminated in the 1970s. While others were forgetting about the molten salt reactor I became more interested but this was not a part of my job. After retiring from full time work in 2000 I increased my effort on the molten salt reactor.

2. Why do you think that the Molten Salt Reactor is important?

It holds the promise of being more economical than our present reactors while using less fuel. I published a paper on this topical that the ORNL people did not feel they could publish. It can come in small sizes without as much of a penalty as is usually the case and can be in large sizes. It can burn thorium thereby getting away from so much buildup of plutonium and higher actinides.

3. What is your relationship to the Fuji Molten Salt Reactor project?

I became familiar with this effort and its leader Professor Furukawa in about 1980 and appreciate his carrying on the ORNL work after they stopped. He has been a friend and colleague ever since.

4. What project is that project making?

The next step in molten salt reactor development should be the construction and operation of a small <10 MWe reactor based largely on the MSRE that operated at ORNL at about & MWth but without electricity production. The FUJI project has not gotten funding and is making no progress other than a paper here and there on some particular aspect.

5. Do you believe that a crash development of the Molten Salt Reactor concept is warranted?

Yes, that is in fact the conclusion of the paper Teller and I wrote. Surprisingly the cost of a crash program is not so great, less than $1B but its progress could be rapid owing to the feasibility proven by the work at ORNL so long ago on MSRE.

6. What is your opinion of the use of carbon-carbon composites in Molten Salt Reactors?

I am impressed by the ideas for use of carbon-carbon composites for high temperature heat exchangers and maybe piping and vessels. If metals are not used in the primary system then the temperature could jump from the 700°C of MSRE to 1000 °C by use of carbon-carbon composites. This development could be rapid by building on the work taking place in industry today.

7. What is any techniques would you suggest to counteract the effects of neutron radiation of graphite and carbon-carbon composites?

I am not very knowledgeable on graphite technology and can only assume small incremental improvements in its radiation damage abilities can be expected. However, I am intrigued by the dedicated effort of a number of individuals who are studying ways of eliminating the use of graphite as a moderator in the molten salt reactor. Perhaps carbon-carbon composites might be used as replaceable shields to protect walls from the direct neutron damage or be used to separate two fluids, an old concept at ORNL that was dropped over three decades ago but composites might resurrect it.