Thorium Report

This was my APUSH paper on thorium, element 90 on the periodic table and a lesser known source of energy. This paper should provide some background on thorium and specifically, why thorium was rejected as a source of energy (as well as the Molten Salt Reactor, the reactor that would use thorium as a primary fuel source). As we progress as a society, thorium should be kept on the radar as a source of energy because of its abundance and potential to be used in breeder reactors, especially as we advance nuclear technology (in the way of fusion, uranium, etc.)

Thorium first brought the attention of influential scientists such as Glenn Seaborg and Eugene Wigner in early 1942 when its product Uranium-233 was shown to be fissile, or usable in nuclear fission. It would later dazzle the likes of John F. Kennedy due to its promise of creating vast amounts of energy and prove successful as a fuel in the Molten Salt Reactor, a radical type of nuclear reactor that promised to change the face of nuclear physics. However, because of politically motivated reasons as opposed to scientific reasons, thorium would ultimately fade into obscurity in the United States due to the stubborn leadership of Milton Shaw, political pressure from the second World War, and the actions of Alvin Weinberg, the administrator of Oak Ridge National Laboratory and an advocate for the power of thorium.

For an element that faded into such obscurity, thorium enjoyed a rich period of research during the Manhattan Project by Glenn Seaborg and Oak Ridge Laboratory with the Molten Salt Reactor (MSR) due to its inherent safety and abundance. Thorium is similar to the infamous isotopes Uranium-235 and Plutonium-238, in that it can be used in nuclear reactors. Its isotope Thorium-232 has a “decay chain,” meaning that it is unstable and will attempt to lose energy by releasing neutrons, protons, and radioactivity, generating different elements in the process. However, a key difference between Thorium-232 and U-235 is that T-232 is considered “fertile,” meaning that it itself is not fissile, but its products along its decay chain are, in this case, thorium’s product Uranium-233. Although thorium had caught the eye of Seaborg and his coworkers, it could not garner interest for research initially because of its inability to become critical by itself. The whole objective of the lab during the Manhattan Project was to refine material, but a pile of thorium would only achieve criticality if supplied with refined material in the form of a fissile element, defeating the purpose of thorium research. Thus, thorium saw little use in the Manhattan Project era but gained interest after the war with the advent of the technology required for the Molten Salt Reactor. Research at Oak Ridge, a national laboratory, was devoted to the study of nuclear aircraft, a seemingly ridiculous idea proposed by Gordon Simmons, an engineer who worked at a production facility related to the Manhattan Project known as K-25. The design of the aircraft involved a nuclear reactor as a power source, which caused many logistical problems, namely the protection of the crew from radiation by way of a 50-100 ton shield and the radiation poisoning a crashed nuclear plane could cause. Although the idea of nuclear aircraft predictably had little success due to its insurmountable technical challenges, the designs that were considered in the project would allow for the establishment of molten salt technologies. The “indirect cycle” of airplane propulsion was considered in particular for the design of the aircraft’s nuclear reactor, where the airplane’s reactor is cooled by a liquid metal. The MSR was characterized by the principles established by the nuclear aircraft experiment: it would operate at extremely high temperatures and be cooled by a molten salt, a salt heated to the point that it enters a liquid state. As well as the establishment of the principle of molten salt cooling, key observations were made concerning the usage of construction elements resistant to high temperatures and corrosion, eventually leading to the usage of structural elements such as Hastelloy, a type of steel highly resistant to heat. After the cancellation of the nuclear aircraft project, breeder reactors were researched at separate locations. Many organizations such as the General Electric Company chose to use the plutonium cycle for reactors, while Oak Ridge chose to study the thorium cycle as a result of Wigner’s interest in the element. Although Wigner first thought of using water as a coolant, he disliked the idea of having a highly concentrated mass of critical plutonium in a reactor and preferred the inherent safety of the MSR and thorium. Called the “most exotic nuclear reactor ever built,” the MSR posed a slew of problems unique from the LWR that discouraged some from pursuing it, most notably, Milton Shaw, the director of reactor development at the Atomic Energy Commission. However, the MSR did have some notable advantages over the traditional LWR. The MSR has a significantly lower pressure during operation, meaning no accidents due to salt leakage or foundational damage can occur and the coolant salts/fuel salts used in the MSR are chemically inert, meaning in the case of an accident, no dangerous reactions with air will occur. Additionally, the MSR has a very negative temperature coefficient of reactivity, which means that the rate of fission decreases as temperature increases, thus preventing a high rate of fission in high temperatures that could potentially cause an accident like the Chernobyl reactor failure. These were all very relevant design flaws in the LWR, as would be proven by Fukushima, a disaster with a Japanese nuclear reactor caused by the reaction of water with structural elements, and the accident at Fermi-1, a reactor that suffered a partial meltdown, both impossibilities for the MSR because of its inert composition and low pressure. Despite the potential advantages of the MSR over the LWR, the MSR’s eventual shortcomings were a result of managerial errors or politically driven decisions.

During the development of the atomic bomb, reactors that used uranium or plutonium would take precedence over thorium-based reactors in research because they were more developed. There was also quite a bit of pressure for faster solutions to the persecution that the Nazis perpetrated from many scientists, notably, the “Martians”. They were a group of Hungarian scientists who had immigrated to the United States to escape persecution, renowned for their near-otherworldly intelligence, which inspired their nickname. Among those scientists were Eugene Wigner and Leo Szilard, both of whom worked on nuclear reactors and faced persecution in Hungary. During the development of reactor coolants in the early 1940s, Wigner was one of the few who argued against the usage of helium as a coolant with “a fierce intensity” that Weinberg, administrator of the ORNL and colleague of Wigner, suspected sprang from Wigner’s belief that “Nazism would prevail unless the Metallurgical Project achieved its goal in the shortest possible time. Wigner counted each day until a bomb was made as an unnecessary gift to the Nazis, and was influenced by the spread of Nazism to expedite the creation of a functioning reactor. The threat of war became ever more relevant with the presence of Soviet spies, and even the very first study of a thermal breeder involving thorium was tampered with. Early measures on the Molten Salt Reactor were performed by Herb Anderson and Alan Nunn May, the latter of which was a Soviet spy who transferred Uranium-233 to a Soviet spy network. The natural response to wartime urgency would be to work on preexisting, more developed technologies, which researchers at Los Alamos eventually did, resulting in the postponement of thorium research. Despite the recognition of the potential thorium had, it was ultimately overshadowed by the haste of World War II and the focus on plutonium manufacture.

While its earlier shortcomings resulted from an urgency caused by the world war, thorium’s eventual shortcomings were primarily a result of internal conflicts in Oak Ridge National Laboratory (ORNL). After the conclusion of the war, the MSR failed to gain support because the MSR was seen as a less economically competitive reactor when compared to the LWR. This was a view held most prominently by Milton Shaw, the director of reactor development at the AEC, or the Atomic Energy Commission, and a major contributor to the downfall of the MSR in the US. In the document “WASH-1222,” Shaw argued against the use of the MSR under the grounds that there were already commitments to reactors such as the LWR, a lack of incentive for industrial investment in molten salt technology, overwhelming experience with solid fueled reactors, less development of MSR/MSBR technology, and a lack of solutions to technological problems. These claims were all demonstrably false or unreasonable. Shaw grossly exaggerates the level of understanding gained of reactors such as the LWR and the LMFBR (Liquid Metal Fast Breeder Reactor) throughout WASH-1222 and uses that as a justification to portray the LWR and LMFBR as superior technologies, which was naive in the face of the failings of the prototype LMFBR Fermi-I. Fermi-I experienced a partial meltdown due to leakage of core fluid just 6 years before the issuing of WASH-1222 that nearly proved catastrophic, and inspired a book called “We Almost Lost Detroit,” implying the reactor’s potential to annihilate an entire city upon failure. The later American LMFBR, the Clinch River Breeder Reactor, was also a failure because of its inability to generate proper economic benefits and was decommissioned despite the billions of dollars required for its assembly as a result of a lack of civilian interest in purchasing plutonium fuel. Shaw also underestimated the potential of the MSR. He claimed that the MSR was underdeveloped in comparison to the LWR but simultaneously deprived Oak Ridge of the resources necessary to develop the MSR in the first place. According to WASH-1222, Shaw states that the MSR was funded at a level of 5 million dollars per year and that 150 million dollars were spent in total, despite the fact that it would require up to 2 billion dollars to create a fully functioning MSR. Shaw’s claims that there was no incentive for the use of the MSR over the LWR and no existing private-industry interest were also inaccurate. There were many private companies interested in molten salt technologies for its unique features and thorium for its abundance. Indeed, Glenn Seaborg remarked that the abundance of thorium could act as a nearly inexhaustible energy source, a “fifty-quadrillion dollar discovery.” The 1970 Bureau of Mines Mineral Yearbook reported that there was a significant increase in private efforts relating to the MSR/MSBR as a result of research in Oak Ridge, as well as the formation of the Molten Salt Breeder Reactor Associates, an association of electric utility companies, and the Molten Salt Group, an association of 15 utility companies and 6 industrial companies. During the writing of “The Molten Salt Adventure” in the 1980s, there was additionally significant international interest in molten salt technology occuring in France, India, the USSR, and Japan. Shaw argued that the MSR had many technical issues, and three prominent issues with the MSR addressed in WASH-1222 pertain to “radiation hardening” of the Hastelloy walls in the reactor, tiny cracks in the Hastelloy pipes of the MSR, and tritium buildup, all supposedly barriers to experimental success. Despite the aforementioned technical problems, the MSR showed significant promise in its experimental phase. MSR researchers Paul Haubenreich and Richard Engel both reflected that “When [the MSR] is measured against the yardstick of other reactors in a comparable stage of development, it is seen to be indeed remarkable.” Indeed, Shaw himself observed that the MSR allowed for less processing of raw material, higher efficiency, and potentially attractive fuel costs. Even the errors listed in WASH-1222 were eventually solved by the scientists that worked on the MSR. Because of WASH-1222’s lack of substantiated analysis of the MSR, WASH-1222 represented a bureaucratic outburst against Oak Ridge rather than an objective report of the MSR’s shortcomings.

Milton Shaw was infamous for his stubborn support of the LWR and LMFBR over alternative technologies such as the MSR and nuclear fusion, almost to the point of illogicality. The AEC Chairman Dixy Lee Ray had difficulty combatting Shaw’s “stated desire” to destroy the Oak Ridge National Laboratory. In addition to Shaw’s belief that the LWR was a technology more promising economically than the MSR, Shaw’s incompatibility with Weinberg’s naive optimism compounded the problem of Oak Ridge’s low funding. Weinberg made a slew of radical predictions concerning nuclear proliferation and the progression of American society in the future over his career. This optimism was best exemplified in his famous talk, Energy as an Ultimate Raw Material, where Weinberg gave his predictions about the future of energy in the far future. Weinberg spoke of “burning the rocks,” or using thorium or uranium fuels in breeder reactors to create more product than initially used and thus infinite energy, as well as using deuterium derived from “burning the sea” for nuclear fusion. Weinberg speculated in the nearer future that thorium breeders could relieve Middle Eastern tensions and unite Arab and Israeli alike. He even suggests that nuclear innovations could address Malthusian dilemmas, in reference to an imbalance of energy provided to man and energy required by man, as infinite nuclear energy should allow humanity to avoid cyclic growth and languishing analogous to Malthus’ theories of population. On the other hand, Shaw worked closely with Rickover, a formal admiral, and adopted an authoritative, pragmatic leadership style. Shaw would not hesitate to abuse his power and bend rules if he saw fit. Additionally, due to his strong relationships with commissioners in the AEC and companies in the nuclear industry, Shaw would face few repercussions to his anti-MSR actions. Weinberg reflected that “Milt tackled the LMFBR project with Rickoverian dedication: woe unto any who stood in his way.” Especially unkind to Oak Ridge, Shaw saw the scientists working on the MSR as people with inflated egos and not in touch with reality, and therefore unfit to create the future of nuclear power. This was reflected in Shaw’s comparatively small allocation of 25 million dollars to build a depository in Lyons, Texas, where the estimated cost for a similar repository, the Yucca Mountain Repository, was about 500 times higher. Shaw’s rejection of the MSR for the LWR and LMFBR culminated in the publishing of WASH-1222, which was in close proximity to the dismissal of Alvin Weinberg. While Weinberg was formally dismissed in 1973, he was first notified he had to leave in late 1972. On the other hand, WASH-1222 was issued in September 1972. Superficially separate, these events suggest a deliberate bureaucratic attack on the ORNL when considering Shaw’s previous actions.

Weinberg, possibly the most important and dedicated proponent of the MSR and thorium research, was not free of responsibility when it came to the downfall of the MSR either.

Weinberg’s lack of assertiveness caused problems very early in the development of thorium-related technologies. During the aircraft research program, Weinberg failed to advocate for the aircraft reactor because he was convinced of its failure. This was credited by his coworkers as something that resulted in the shutdown of the aircraft research program, and Weinberg was “chewed out” for about an hour as a result, being seen as traitorous by Don Keirn, AEC’s manager of Aircraft Nuclear Propulsion, and Kenneth Davis, the director of development for the AEC. Weinberg also failed to expand the MSR’s influence outside of Oak Ridge, which was arguably a major factor in the cessation of MSR research in the USA. Had the MSR program been expanded to a demonstration plant sooner in development, it may have been able to challenge the momentum that the LMFBR had gained. Later in Weinberg’s career, he became a figurehead of the nuclear movement and made statements that would degrade the position of nuclear scientists. Weinberg reflected that the development of nuclear energy had horrible timing, as environmentalism became increasingly relevant with the publishing of Rachel Carson’s seminal work Silent Spring, that primarily discussed the dangers of chemicals and radiation to the environment. Carson described the detriments in radiation in excruciating detail, describing how the “assault” of radiation affects cells in a variety of ways, including an impairment of cell division or changes in chromosome structure, which would bring the issue of radioactive contaminants to the forefront in America. Unlike many other nuclear advocates, Weinberg was willing to concede the dangers of nuclear energy, best exemplified by his famous referral of nuclear power as a “Faustian bargain,” or a deal with the devil that brought calamity if misused. Weinberg’s concession-riddled advocacy for nuclear power drew criticism from fellow nuclear physicists and opponents alike, evident by threats directed at Weinberg during a speech at the University of Strasbourg and catcalls in a presentation at Ralph Nader’s antinuclear group called Critical Mass. The idea of nuclear safety was one that drew upon the fear that the public had of the power of the nuclear bomb. Nuclear reactors would create large amounts of radiation and had the potential to cause catastrophe like a bomb where other sustainable technologies such as solar power could have been alternatively pursued without risk to the public. Weinberg realized that he had not given enough thought to the problem of nuclear waste from the MSR, as public concerns about radiation exposure were growing ever more relevant. Indeed, if Weinberg had been able to demonstrate the ability to create a safe depository, the MSR may have been one step closer to being accepted by the general public.

Weinberg’s ultimate flaw was that he was a scientist through and through, not a powerful advocate. Sound of mind but not of rhetoric, Weinberg failed to push the MSR to the forefront where a vehement advocate like Shaw or Rickover may have been able to. Weinberg was too cognizant of the weaknesses of technology and unaware of how his superiors would react to the MSR. He refused to compromise with his inflexible superiors but was willing to do so with his ideological opponents due to his great idealism. Who was to blame for the death of the MSR, a technology that showed concrete promise? The ones in administrative positions such as Shaw were too inflexible and single-minded, while the developers of the MSR such as Weinberg were unaware of the importance of convincing individuals of the worth of a technology. As Weinberg reflected later, “a technology that differs too much from an existing technology” must “demonstrate its feasibility” and “convince influential individuals and organizations who are intellectually and emotionally attached to a different technology that they should adopt the new path” as well. The MSR presented a unique and wasted opportunity. As of now, the MSR, its proponents, and its dissenters have all faded into obscurity. Weinberg spoke of a “second nuclear era” during the waning years of his career. The only hope for the resurrection of molten salt technology would be a movement that channels the same creative creative energy that Weinberg had seen in his years at Oak Ridge and avoids pitfalls made painfully apparent by the internal tension in Oak Ridge Laboratory caused by war and conflicts of interest between administrators and innovators.

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