An Interesting Master's Thesis on 1943's X-10 Nuclear Reactor, the World's First Continuously Run Nuclear Reactor.

[NNadir]

The X-10 Nuclear Reactor, at Oak Ridge National Laboratory was "overbuilt" in 1943, in ten months under what were (then) considered "emergency" conditions - the "emergency" being the fear that the Germans would build a nuclear Weapon before the Americans did.

The reactor is still there, and can be visited on the Oak Ridge Laboratory's public tour. I went there when my son, as an undergraduate, interned there. It's quite impressive to see; they have mannikins representing the real operators of the reactors, who pushed aluminum clad fuel pellets through the core using poles. The reactor was used to synthesize the first visible samples of the important element plutonium, in which my view, is key to saving what is left to save and restore that which can be subject to restoration. The control room - which had no means of physical control but contained what seemed to be the equivalent of adding machines and typewriters - is about the size of a kitchenette presumably used for performing calculations to guide the workers pushing the fuel and control rods through the core.

The Wikipedia page on the X10 Graphite Reactor has a nice photograph of the device in operation and a nice overview, including this text:

Using designs by the Metallurgical Laboratory, DuPont commenced construction of the plutonium semiworks at the Clinton Engineer Works in Oak Ridge on February 2, 1943. The reactor went critical on November 4, 1943, and produced its first plutonium in early 1944. The reactor and chemical separation plant provided invaluable experience for engineers, technicians, reactor operators, and safety officials who then moved on to the Hanford Site.

The reactor, which required a grade of graphite that was not available in 1940, was built and began operations in 275 days, that is in 9 months and two days, operated until 1963, exactly 20 years after starting, which is roughly two years longer than the average time a modern wind turbine lasts before becoming landfill. After the war it was primarily used to provide medical, research, and industrial radionuclides.

When surveying nuclear graduate schools and their faculties to advise my son on which schools he should consider, I looked into Georgia Tech; but looking over my notes from then which I shared with him, Georgia Tech didn't strike me as all that impressive. I don't recall that he applied there. I seem to have missed something, since the Master's Thesis from that institution, considering what ratios of fission products meant in consideration of whether the reactor was designed for the production of weapons or of power or for other service to humanity is quite impressive.

It's here: X-10 REACTOR FORENSIC ANALYSIS AND EVALUATION USING A SUITE OF NEUTRON TRANSPORT CODES .

I consider that after many years of study that I know quite a bit about fission product generation, but nevertheless I learned quite a bit about how fission product ratios, as opposed to actinide isotopic ratios, can differentiate the purposes for which reactors operate, although this is quite clear when the issue is detonation of a nuclear weapon. This should have been clear to me with respect to the operation of reactors and their purpose, and on reflection, it's obvious, but I actually never thought about it explicitly in detail as described in the thesis.

The thesis also covers some interesting history of nuclear modeling codes, such as MCNP, which are older than I thought.

The opening section of the paper gives some history similar to that at the Wikipedia page, including some fascinating information on cooling the reactor, which I have bolded:

The “Manhattan Project” would bring together the most prestigious scientists of the Twentieth Century. The Manhattan Project was named after the Manhattan Engineer District, set up by the Army Corps of Engineering to develop and manufacture the atomic bomb. Oak Ridge, Tennessee would become the site of the experimental facilities used for the production and research necessary to build the first atomic bomb. This Manhattan pilot site would contain the air-cooled experimental pile, a separation plant and many supporting facilities. The secrecy surrounding Oak Ridge was of such importance to national security that the Governor of Tennessee was unaware of its existence. The X-10 graphite reactor was built at the Oak Ridge location, together with similar reactors at the Hanford site in Washington State, supplied the Los Alamos Scientific Laboratory with the plutonium necessary for the Manhattan Project. Los Alamos conducted studies on these samples which heavily influenced weapon design. It is also noteworthy that neutron-cross-section studies, radiation-damage studies, and biological radiation-effect studies were conducted at these Oak Ridge facilities.

2 The X-10 reactor sustained the fission reaction on November 4, 1943 using natural uranium fuel from the natural abundance of the fissile atom U-235. Since natural uranium contains 0.72 atom percent U-235, with the remainder of the uranium as U-238 with a very small fraction of U-234, natural uranium is excellent fuel for the manufacture of plutonium, which results from neutron capture in U-238 and transmutation through decay to result in Pu-239 .

The excess neutrons produced from the fission of the U-235 atom are used in the production of Pu-239. . The reactor was designed and built in approximately 10 months by the du Pont de Nemours Company (“DuPont”) assisted by the University of Chicago. The short time of conception to completion presented an overdesign of most of the components involved with the reactor. The air-cooling system allowed continuous operation at One Mega-Watt (MW) power level. There were also many openings throughout the graphite matrix that served as research openings for the studies cited above.

I have, in recent years, considered that air cooled Brayton type nuclear reactors are desirable, if only to clean up the air as a side product of operation, and I am familiar with high temperature gas cooled reactors using helium (HTGRs) and/or carbon dioxide (British AGCRs) working fluids, but I did not know that the first continuously operated nuclear reactor - which did not produce power - was air cooled. Of course, in the period between 1943-1963 the atmosphere was not as rich in carbon dioxide, chlorofluorocarbons, fluorinated hydrocarbons, perfluorocarbons, sulfates, N₂O and SF₆, etc. as it is now. The air was cleaner then. It would have been cleaner now were nuclear energy not demonized by people who don't know a damned thing about nuclear energy other than that they hate it.

Eventually the reactor was brought up to 4 MW of thermal power, meaning it was a relatively small reactor, much smaller than commercial reactors which operate at generally around 600-1200 MW_e, 1800-3600 MW_th.

The operative point is that the reactor was built and operated in 275 days because at the time, it was considered to be under emergency conditions, the threat of Hitler having a nuclear weapon.

Oddly, there is a much greater disaster now well underway than even the greatest war disaster ever to take place, the events between 1937 and 1945, beginning in China and ending Japan in the only nuclear war ever observed - although the greatest death toll in that period was connected with dangerous fossil fuel weapons of mass destruction, which still are widely used in wars almost continuously. In the only nuclear war ever observed, nuclear related deaths were comparably trivial, just as Chernobyl and Fukushima, which generate much angst among antinukes who couldn't care less about fossil fuels, have trivial death tolls in comparison to continuous fossil fuel waste related deaths, numbering about 7 million per year, not even including the extreme heating observed from greenhouse gas concentrations. That war, generally called "World War II," was largely fought to gain access to fossil fuels, at least as far as the Japanese were concerned in modern day Indonesia, and on the part of the the Germans, in Russia. World War II, like many modern wars, was an oil war more than it was a nuclear war.

That modern, worse, disaster than World War II is of course, the collapse of the planetary atmosphere.

Despite the history of the X-10, the very first reactor, designed by scientists and engineers with computational tools inferior to a modern Apple watch, mostly slide rules probably, being built in 9 months and two days, we still have a lot of very uneducated types whining incessantly that nuclear reactors take "too long" to build.

We might ask ourselves why that is, but at this point, near the end of my life, I do not consider that people think very clearly about what a true disaster is or might be. We face something far more serious than a German nuclear weapon in 1945 might have been, the destruction of the planetary atmosphere and all the species and ecosystems it supports.

Have a nice day.