This newspaper article was published on February 13, 1973 in a local Oak Ridge newspaper, and it was recently recovered from the personal archives of one of the key persons on the Molten-Salt Reactor Program.
Molten Salt: 500 Worked For 25 Years
By CAROLYN KRAUSE
The recent termination of Oak Ridge National Laboratory’s Molten Salt Reactor Program was a bitter disappointment to the 100 people directly connected with it, but it was hardly unexpected.
Some could see the dark clouds on the horizon as early as 1967. For them, it has been only a question of when, not whether fiscal lightning would strike and end the program.
On January 29 (1973), the U.S. Atomic Energy Commission announced in its budget proposal requests for fiscal 1974 (beginning July 1) that the $5 million-a-year MSR program, based entirely in Oak Ridge, is to be eliminated.
But the decision did not come as a shock, according to H.G. MacPherson, former ORNL deputy director and now a professor of nuclear engineering at the University of Tennessee in Knoxville.
MacPherson, who was involved in the MSR program for many years, said in an interview last week that a 1967 supplemental report to the President did not imply that the molten salt breeder project “would be a major program unless something disastrous happened to the liquid metal fast breeder reactor.”
In other words, the molten salt breeder project has been viewed by the federal government in the past few years as a backup–an alternative to the LMFBR.
The irony of all this for Oak Ridgers is that this town is becoming in the same decade a birthplace for one type of breeder project and a graveyard for another.
For, while 1972 was the last year for the MSR program, it was also the year in which it was announced that the AEC and a host of utilities will provide the money to build the nation’s first large-scale LMFBR demonstration power plant. And this plant–the “priority project” of the AEC–is to be built in Oak Ridge.
The tragedy of the MSR program termination is that some 500 scientists and engineers have worked directly or indirectly with the program, some for as long as 25 years.
These professional people represent a number of ORNL divisions, including the reactor, reactor chemistry, chemical technology and metals and ceramics divisions.
Is there a future for the molten salt breeder anywhere–in the U.S. or in the world?
MacPherson, who points out that a handful of people in France, England and India have shown interest in molten salt technology, said he sees “hope for some international venture” in which various U.S. industries and foreign nations would contribute to a molten salt breeder project. But he does not know how such a venture could get started.
In the U.S. there is a Molten Salt Group consisting of utilities and industrial organizations which have been investing money and doing design work for molten salt breeders. Murray Rosenthal, ORNL’s MSR program director, has said that industry is interested in the MSBR “but they say they can’t afford to do it. It takes a government commitment” such as the LMFBR has.
Studies of molten salt reactors as a power source began in 1947 when the US began to work on developing a nuclear-powered airplane. The aircraft never got off the ground, but the molten salt reactor did become a reality. Ed Bettis was a strong proponent of molten salt work at ORNL.
Some of the highlights of molten salt studies at ORNL are as follows, according to a published history written by Rosenthal, P.R. Kasten and R.B. Briggs:
1950 – Studies of molten fluoride salts (heated compounds consisting of fluorine and various metals) became the “main line effort” of ORNL’s Aircraft Nuclear Propulsion Program.
1954 – The Aircraft Reactor Experiment (ARE), a small reactor built in Oak Ridge to look into the use of molten fluoride fuels for aircraft propulsion reactors, operated successfully for nine days.
1956 – H.G. MacPherson formed a group to study the possible use of molten salt reactors in civilian power plants. MacPherson and his associates “concluded that graphite-moderated thermal reactors operating on a thorium fuel cycle would be the best molten-salt systems for producing economic power.”
1959 – An AEC task force, after comparing the different kinds of fluid fuel reactors being developed, concluded that the molten salt reactor had “the highest probability of achieving technical feasibility.” MacPherson, who represented the molten salt concept at meetings of the task force, recalled that this task force report favoring the MSR was a personal triumph for him.
1960 – The design of the Molten Salt Reactor Experiment (MSRE) was begun. It was determined then that MSRE fuel salt would be a mixture of uranium, lithium, beryllium and zirconium fluorides.
1962 – Construction of the MSRE began.
1965 – The molten salt reactor was first critical, that is, the fissioning, or atom-splitting of the fuel, was triggered.
Oct. 2, 1968 – The MSRE was made critical on uranium-233.
Oct. 8, 1968 – Glenn T. Seaborg, then AEC chairman, personally at the controls, took the power of the MSRE up to 100 kilowatts, thus bringing to power the first reactor to operate on uranium-233.
According to MacPherson, the “MSRE demonstrated that you could operate a liquid fuel reactor by circulating a highly radioactive fuel through the reactor system.”
After the MSRE was proven successful, the Molten Salt Reactor Program was directed, beginning in 1968, toward the development of a single-fluid breeder reactor.
In the LMFBR, breeding is accomplished when uranium-238 captures neutrons escaping in the fission process. These neutrons convert the uranium-238 to fissionable plutonium-239, which can be extracted and used to refuel a breeder reactor.
In a molten salt breeder, neutrons released in the fission process are slowed down by graphite and captured by thorium salt, which is changed into protactinium. The protactinium salt decays into fissionable uranium-233. This uranium is collected and run back into the reactor to keep the fission process going.
The breeder development work in ORNL’s MSR program ran into a snag in 1971 when it was discovered that surface cracking was taking place in Hastelloy-N, the nickel-base alloy in the reactor vessel and heat exchanger tubes.
It was later found that tellurium, one of numerous fission products, was causing the cracking. Last year ORNL engineers learned that, by adding titanium to the Hastelloy-N, both the cracking problem and radiation embrittlement of Hastelloy-N could be licked.
Also, in 1972, technological advances were made in containing radioactive tritium in molten salt reactors. But while the technological outlook for molten salt breeder development looked bright here, the molten salt clouds in Washington grew darker.
Last spring, the Joint Congressional Committee on Atomic Energy invited the AEC to review the molten salt project and decide whether the project should be terminated or expanded.
In anticipation of this review, the ORNL staff prepared a report recommending continuation and some expansion of the present effort with the goal of ultimately constructing for the AEC a molten salt breeder experiment.
But the AEC said no and ended the molten salt project.
Once again, the consistent answer to the question of “why was molten-salt killed?” is “because they wanted the plutonium fast-breeder reactor.” But then the inevitable follow-on question persists–why did they want the fast breeder so badly?