Wednesday, December 12, 2007

Charles Julian Barton, Sr. at Y-12

I talked with my father, Charles Barton, Sr., yesterday about his ORNL career. He is not a good communicator. His speech as always been halting, and he does not organize his memories into well formed stories. I can see that Interviewing him will be a process, and that information will come out in little snippets. My father's view of the the importance of the information might not be the same as mine, or of histories. What I have learned so far:

My father views his work on the separation of Zirconium and Hafnium. Zirconium and Hafnium are "rare earths." They are chemically similar, and thus not easy to separate. About 1% to 3% of refined Zirconium is Hafnium. Inside a reactor Zirconium and Hafnium behave very differently. Zirconium has a low neutron cross section. That means it is unlikely to capture neutrons inside a reactor. Capturing neutrons slows down or even stops chain reactions. Zirconium also resists corrosion. This makes it an ideal metal to use inside a reactors, especially as a cladding for fuel elements in light water reactors. Hafnium is has a high neutron cross section. It is 600 times more likely than Zirconium to capture neutrons inside a reactor, and unless separated from Zirconium, will poison chain reactions. Hafnium is also used inside reactors as control rods.

The chemical, and metallurgical properties of Zirconium made it an ideal material for light water reactors. During the 1940's the Navy saw that reactors could revolutionize the propulsion of submarines. They looked at two designs, one using sodium as a coolant. The history of sodium cooled reactors has always been a troubled one, and the Navy did not master the technology. The second naval reactor concept, patented by Alvin Weinberg, was the light water reactor. Pure zirconium was needed in order to get good performance from the light water reactors. Thus the development of both the atomic submarine and civilian light water reactors became possible. Today 85% of the world's commercial reactors are light water reactors that use Zarconium fuel cladding.

My father's first job at Y-12 in 1948, was to work along with Lyle Overholser, and J.W. Ramsey, to develop an industrial process for separating Zirconium and Hafnium. Lyle and my father had been a PhD students together at the University of Virginia in the 1930's. J.W. Ramsey was the father of a long time friend Jim Ramsey. Previous literature reported the use of ether . But the volitility of ether made it difficult to work with. My father and Lyle Overholser tried various organic solvents with little sucess. Then one day Ramsey showed up with a jug of hexone, and suggested that they try it. The hexone workes well, and the hexone process is still used for seperation in the United States. The separation process turned out well, and the light water became the corner stone of the first nuclear age. The names of L.B. Overholser, C.J. Barton, Sr., and J.W. Ramsey are on the patent. The patent describes the separation process:

The separation of hafnium impurities from zirconium can be accomplished by means of organic solvent extraction. The hafnium-containing zirconium feed material is dissolved in an aqueous chloride solution and the resulting solution is contacted with an organic hexone phase, with at least one of the phases containing thiocyanate. The hafnium is extracted into the organic phase while zirconium remains in the aqueous phase. Further recovery of zirconium is effected by stripping the onganic phase with a hydrochloric acid solution and commingling the resulting strip solution with the aqueous feed solution. Hexone is recovered and recycled by means of scrubbing the onganic phase with a sulfuric acid solution to remove the hafnium, and thiocyanate is recovered and recycled by means of neutralizing the effluent streams to obtain ammonium thiocyanate.

The History of ORNL states:

"Herbert Pomerance later that year discovered that zirconium's capability for neutron absorption had been vastly overstated because of its contamination by the element hafnium, which had a much greater poisoning effect.

Zirconium minerals have traces of hafnium, whose chemical characteristics are nearly identical to zirconium's, making economical separation of the two difficult. With funding from Captain Rickover and the Navy, laboratory researchers across the country investigated ways to separate the two elements. In 1949, chemical technologists at the Y-12 Plant, under the direction of Warren Grimes, developed a successful separation technique and scaled it to production level under the direction of Clarence Larson, then superintendent of the Y-12 Plant.

Zirconium alloys became essential first to the Navy's reactors and later to commercial power reactors. Zirconium rods filled with uranium pellets made up the fuel cores of nearly all light-water reactors, and hafnium was used in the control rods to regulate nuclear reactions. "

After the industrial facilities for purifying Zirconium were established at Y-12, the Y-12 Chemistry group was transfered administratively to ORNL. My father was moved to X-10 to work on the aqueous homogeneous reactor. Although little known now, the Aqueous homogeneous reactor was quite successful. It might have received a great deal more attention had not ORNL been also developing an even more promising concept, the Molten Salt Reactor.

At least one ORNL technical report reflects my father's aqueous homogeneous reactor research,
PHASE STABILITY OF HOMOGENEOUS REACTOR HOT FUEL SOLUTIONS. He was the lead writer along with J.S. Gill, GM Habert, WL Marshall, and RE Moore.

The History of ORNL reports:

"In 1952 the Lab built a small (1-megawatt) ``homogeneous'' reactor, one in which a liquid uranium solution was used both as fuel and as the source of steam to spin a generator's turbine. Besides offering potentially higher generating efficiencies than solid-fuel designs, it offered and important operation advantage: Its fuel solution could be routed continuously through a processing plant for purification and replenishment so the reactor would not require shutdowns for refueling. In 1957 ORNL built a larger homogeneous reactor, one modified to irradiate thorium and ``breed'' uranium while it generated power. But by then work on a solid-fuel breeder was well under way, and the AEC soon abandoned the liquid-fuel alternative."

The next post on my father's ORNL career will deal with his role in the development of Molten Salt Reactors.


Joffan said...

Fascinating insights from an early worker important in the field. Thanks so much for this series and I trust that you will get a great deal out of it too; I guess you're lucky to still have your father around to spend time with.

...and from the name of your other blog I'm guessing that your son is called Charles also.

meta-comment: if you could put a few links in your articles (especially when they refer to other web material), I'd be most grateful.

Sovietologist said...

I really like the aqueous homogeneous reactor design- I picked up some great original 1950s literature on the project at the Oak Ridge library booksale a few years ago. But I think the ORNL engineers were right that the molten-salt reactor is a better idea.

Speaking of ORNL scientists from the old days, I grew up next door to Don Trauger. Have you read his memoirs?
Interesting account of ORNL from the 1940s until the 1990s.


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