The bismuth-phosphate process was used to extract plutonium from irradiated uranium taken from nuclear reactors. [1] [2] It was developed during World War II by Stanley G. Thompson, a chemist working for the Manhattan Project at the University of California, Berkeley. This process was used to produce plutonium at the Hanford Site. Plutonium was used in the atomic bomb that was used in the atomic bombing of Nagasaki in August 1945. The process was superseded in the 1950s by the REDOX and PUREX processes.
During World War II, plutonium was used make both the first atomic bomb ever to be detonated (near Alamogordo, New Mexico) and the atomic bomb that was dropped on Nagasaki in Japan. Plutonium had only been isolated and chemically identified in 1941, so little was known about it, but it was thought that plutonium-239, like uranium-235, would be suitable for use in an atomic bomb. [3]
Plutonium could be produced by irradiating uranium-238 in a nuclear reactor [4] , but developing and building a reactor was a task for the Manhattan Project physicists. The task for the chemists was to develop a process to separate plutonium from the other fission products produced in the reactor, to do so on an industrial scale at a time when plutonium could be produced only in microscopic quantities, [5] and to do so while working with dangerously radioactive chemicals like uranium—the chemistry of which little was known—and plutonium, the chemistry of which almost nothing was known.
Chemists explored a variety of methods for separating plutonium from the other products that came out of the reactor:
While the chemical engineers worked on these problems, Seaborg asked Stanley G. Thompson, a colleague at Berkeley, to have a look at the possibility of a phosphate process because it was known that the phosphates of many heavy metals were insoluble in an acid solutions.
Thompson tried phosphates of thorium, uranium, cerium, niobium and zirconium without success. He did not expect bismuth phosphate (BiPO
4) to work any better, but when he tried it on December 18, 1942, he was surprised to find that it carried 98 percent of the plutonium in solution. [9] The crystalline structure of bismuth phosphate is similar to that of plutonium phosphate, and this became known as the bismuth phosphate process. [10] [11]
Cooper and Burris B. Cunningham were able to replicate Thompson's results, and the bismuth phosphate process was initially adopted as a fallback in case the lanthanum fluoride process could not be made to work. The processes were similar and the equipment used for lanthanum fluoride could be adapted for use with Thompson's bismuth phosphate process. [9] In May 1943, the DuPont engineers decided to adopt the bismuth phosphate process for use in the Clinton semiworks and the Hanford production site. [7]
As Brown, Hill, and other chemists explored plutonium chemistry, [12] they made the crucial discovery that plutonium has two oxidation states, a tetravalent (+4) state and a hexavalent (+6) state, which have different chemical properties that could be exploited. [13] (This work was performed at the Manhattan Project's Radiation Laboratory at the University of California, Metallurgical Laboratory at the University of Chicago and Ames Laboratory at Iowa State College.)
The bismuth phosphate process involved taking the irradiated uranium fuel slugs and removing their aluminium cladding. Because there were highly radioactive fission products inside, this had to be done remotely behind a thick concrete barrier. [14] This was done in the "Canyons" (B and T buildings) at Hanford. The slugs were dumped into a dissolver, covered with sodium nitrate solution and brought to a boil, followed by slow addition of sodium hydroxide. After removing the waste and washing the slugs, three portions of nitric acid were used to dissolve the slugs. [15] [16]
The second step was to separate the plutonium from the uranium and the fission products. Bismuth nitrate and phosphoric acid were added, producing bismuth phosphate, which was precipitated carrying the plutonium with it. This was very similar to the lanthanum fluoride process, in which lanthanum fluoride was used as the carrier. [17] The precipitate was removed from the solution with a centrifuge and the liquid discharged as waste. Getting rid of the fission products reduced the gamma radiation by 90 percent. The precipitate was a plutonium-containing cake which was placed in another tank and dissolved in nitric acid. Sodium bismuthate or potassium permanganate was added to oxidize the plutonium. [15] Plutonium would be carried by the bismuth phosphate in the tetravalent state but not in the hexavalent state. [17] The bismuth phosphate would then be precipitated as a by product, leaving the plutonium behind in solution. [15]
This step was then repeated in the third step. The plutonium was reduced again by adding ferrous ammonium sulfate. Bismuth nitrate and phosphoric acid were added and bismuth phosphate precipitated. It was dissolved in nitric acid and the bismuth phosphate was precipitated. This step resulted in reducing the gamma radiation by four more orders of magnitude, so the plutonium-bearing solution now had 100,000-th of the original gamma radiation. The plutonium solution was transferred from the 221 buildings to the 224 buildings, through underground pipes. In the fourth step, phosphoric acid was added and the bismuth phosphate precipitated and removed; potassium permanganate was added to oxidize the plutonium. [18]
In the "crossover" step, the lanthanum fluoride process was used. Lanthanum salts and hydrogen fluoride were added again and lanthanum fluoride was precipitated, while hexavalent plutonium was left in solution. This removed lanthanides like cerium, strontium and lanthanum, that bismuth phosphate could not. The plutonium was again reduced with oxalic acid and the lanthanum fluoride process was repeated. This time potassium hydroxide was added to metathesize the solution. Liquid was removed with a centrifuge and the solid dissolved in nitric acid to form plutonium nitrate. At this point, a 330-US-gallon (1,200 L) batch sent would have been concentrated to 8 US gallons (30 L). [18]
The final step was carried out at the 231-Z building, where hydrogen peroxide, sulfates and ammonium nitrate were added to the solution and the hexavalent plutonium was precipitated as plutonium peroxide. This was dissolved in nitric acid and put into shipping cans, which were boiled in hot air to produce a plutonium nitrate paste. Each can weighed about 1 kg and was shipped to the Los Alamos Laboratory. [18] Shipments were made in a truck carrying twenty cans and the first arrived at Los Alamos on 2 February 1945. [19] The plutonium was used in the Fat Man bomb design tested in the Trinity nuclear test on 16 July 1945, and in the bombing of Nagasaki on 9 August 1945. [20]
In 1947, experiments began at Hanford on a new REDOX process using methyl isobutyl ketone (codenamed hexone) as the extractant, which was more efficient. Construction of a new REDOX plant commenced in 1949 and operations began in January 1952, the B plant closing that year. Improvements to the T plant resulted in a 30 percent increase in productivity and improvements were made to the B plant. There were plans to reactivate the B plant but the new PUREX plant that opened in January 1956 was so efficient that the T plant was closed in March 1956 and plans to reactivate the B plant were abandoned. [21] By 1960, the PUREX plant's output had surpassed the combined output of the B and T plants and the REDOX plant. [22]
The actinide or actinoid series encompasses at least the 14 metallic chemical elements in the 5f series, with atomic numbers from 89 to 102, actinium through nobelium. The actinide series derives its name from the first element in the series, actinium. The informal chemical symbol An is used in general discussions of actinide chemistry to refer to any actinide.
The Manhattan Project was a research and development program undertaken during World War II to produce the first nuclear weapons. It was led by the United States in collaboration with the United Kingdom and Canada. From 1942 to 1946, the project was directed by Major General Leslie Groves of the U.S. Army Corps of Engineers. Nuclear physicist J. Robert Oppenheimer was the director of the Los Alamos Laboratory that designed the bombs. The Army program was designated the Manhattan District, as its first headquarters were in Manhattan; the name gradually superseded the official codename, Development of Substitute Materials, for the entire project. The project absorbed its earlier British counterpart, Tube Alloys, and subsumed the program from the American civilian Office of Scientific Research and Development. The Manhattan Project employed nearly 130,000 people at its peak and cost nearly US$2 billion, over 80 percent of which was for building and operating the plants that produced the fissile material. Research and production took place at more than 30 sites across the US, the UK, and Canada.
Uranium is a chemical element; it has symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium radioactively decays, usually by emitting an alpha particle. The half-life of this decay varies between 159,200 and 4.5 billion years for different isotopes, making them useful for dating the age of the Earth. The most common isotopes in natural uranium are uranium-238 and uranium-235. Uranium has the highest atomic weight of the primordially occurring elements. Its density is about 70% higher than that of lead and slightly lower than that of gold or tungsten. It occurs naturally in low concentrations of a few parts per million in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite.
The Hanford Site is a decommissioned nuclear production complex operated by the United States federal government on the Columbia River in Benton County in the U.S. state of Washington. It has also been known as Site W and the Hanford Nuclear Reservation. Established in 1943 as part of the Manhattan Project, the site was home to the Hanford Engineer Works and B Reactor, the first full-scale plutonium production reactor in the world. Plutonium manufactured at the site was used in the first atomic bomb, which was tested in the Trinity nuclear test, and in the Fat Man bomb used in the bombing of Nagasaki.
Nuclear reprocessing is the chemical separation of fission products and actinides from spent nuclear fuel. Originally, reprocessing was used solely to extract plutonium for producing nuclear weapons. With commercialization of nuclear power, the reprocessed plutonium was recycled back into MOX nuclear fuel for thermal reactors. The reprocessed uranium, also known as the spent fuel material, can in principle also be re-used as fuel, but that is only economical when uranium supply is low and prices are high. Nuclear reprocessing may extend beyond fuel and include the reprocessing of other nuclear reactor material, such as Zircaloy cladding.
PUREX is a chemical method used to purify fuel for nuclear reactors or nuclear weapons. PUREX is the de facto standard aqueous nuclear reprocessing method for the recovery of uranium and plutonium from used nuclear fuel. It is based on liquid–liquid extraction ion-exchange.
The Metallurgical Laboratory was a scientific laboratory at the University of Chicago that was established in February 1942 to study and use the newly discovered chemical element plutonium. It researched plutonium's chemistry and metallurgy, designed the world's first nuclear reactors to produce it, and developed chemical processes to separate it from other elements. In August 1942 the lab's chemical section was the first to chemically separate a weighable sample of plutonium, and on 2 December 1942, the Met Lab produced the first controlled nuclear chain reaction, in the reactor Chicago Pile-1, which was constructed under the stands of the university's old football stadium, Stagg Field.
Uranium-233 is a fissile isotope of uranium that is bred from thorium-232 as part of the thorium fuel cycle. Uranium-233 was investigated for use in nuclear weapons and as a reactor fuel. It has been used successfully in experimental nuclear reactors and has been proposed for much wider use as a nuclear fuel. It has a half-life of 160,000 years.
The X-10 Graphite Reactor is a decommissioned nuclear reactor at Oak Ridge National Laboratory in Oak Ridge, Tennessee. Formerly known as the Clinton Pile and X-10 Pile, it was the world's second artificial nuclear reactor and the first designed and built for continuous operation. It was built during World War II as part of the Manhattan Project.
Plutonium is a chemical element; it has symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation states. It reacts with carbon, halogens, nitrogen, silicon, and hydrogen. When exposed to moist air, it forms oxides and hydrides that can expand the sample up to 70% in volume, which in turn flake off as a powder that is pyrophoric. It is radioactive and can accumulate in bones, which makes the handling of plutonium dangerous.
The Fernald Feed Materials Production Center is a Superfund site located within Crosby Township in Hamilton County, Ohio, as well as Ross Township in Butler County, Ohio, in the United States. It was a uranium processing facility located near the rural town of New Baltimore, about 20 miles (32 km) northwest of Cincinnati, which fabricated uranium fuel cores for the U.S. nuclear weapons production complex from 1951 to 1989. During that time, the plant produced 170,000 metric tons uranium (MTU) of metal products and 35,000 MTU of intermediate compounds, such as uranium trioxide and uranium tetrafluoride.
The Dayton Project was a research and development project to produce polonium during World War II, as part of the larger Manhattan Project to build the first atomic bombs. Work took place at several sites in and around Dayton, Ohio. Those working on the project were ultimately responsible for creating the polonium-based modulated neutron initiators that were used to begin the chain reactions in the atomic bombs.
The RaLa Experiment, or RaLa, was a series of tests during and after the Manhattan Project designed to study the behavior of converging shock waves to achieve the spherical implosion necessary for compression of the plutonium pit of the nuclear weapon. The experiment used significant amounts of a short-lived radioisotope lanthanum-140, a potent source of gamma radiation; the RaLa is a contraction of Radioactive Lanthanum. The method was proposed by Robert Serber and developed by a team led by the Italian experimental physicist Bruno Rossi.
Harrison Scott Brown was an American nuclear chemist and geochemist. He was a political activist, who lectured and wrote on the issues of arms limitation, natural resources and world hunger.
Actinide chemistry is one of the main branches of nuclear chemistry that investigates the processes and molecular systems of the actinides. The actinides derive their name from the group 3 element actinium. The informal chemical symbol An is used in general discussions of actinide chemistry to refer to any actinide. All but one of the actinides are f-block elements, corresponding to the filling of the 5f electron shell; lawrencium, a d-block element, is also generally considered an actinide. In comparison with the lanthanides, also mostly f-block elements, the actinides show much more variable valence. The actinide series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium.
The Ames Project was a research and development project that was part of the larger Manhattan Project to build the first atomic bombs during World War II. It was founded by Frank Spedding from Iowa State College in Ames, Iowa as an offshoot of the Metallurgical Laboratory at the University of Chicago devoted to chemistry and metallurgy, but became a separate project in its own right. The Ames Project developed the Ames Process, a method for preparing pure uranium metal that the Manhattan Project needed for its atomic bombs and nuclear reactors. Between 1942 and 1945, it produced over 1,000 short tons (910 t) of uranium metal. It also developed methods of preparing and casting thorium, cerium and beryllium. In October 1945 Iowa State College received the Army-Navy "E" Award for Excellence in Production, an award usually only given to industrial organizations. In 1947 it became the Ames Laboratory, a national laboratory under the Atomic Energy Commission.
High Explosive Research (HER) was the British project to develop atomic bombs independently after the Second World War. This decision was taken by a cabinet sub-committee on 8 January 1947, in response to apprehension of an American return to isolationism, fears that Britain might lose its great power status, and the actions by the United States to withdraw unilaterally from sharing of nuclear technology under the 1943 Quebec Agreement. The decision was publicly announced in the House of Commons on 12 May 1948.
The Hanford Engineer Works (HEW) was a nuclear production complex in Benton County, Washington, established by the United States federal government in 1943 as part of the Manhattan Project during World War II. It built and operated the B Reactor, the first full-scale plutonium production reactor. Plutonium manufactured at the HEW was used in the atomic bomb detonated in the Trinity test in July 1945, and in the Fat Man bomb used in the atomic bombing of Nagasaki in August 1945. The plant continued producing plutonium for nuclear weapons until 1971. The HEW was commanded by Colonel Franklin T. Matthias until January 1946, and then by Colonel Frederick J. Clarke.
Neptunium compounds are compounds containing the element neptunium (Np). Neptunium has five ionic oxidation states ranging from +3 to +7 when forming chemical compounds, which can be simultaneously observed in solutions. It is the heaviest actinide that can lose all its valence electrons in a stable compound. The most stable state in solution is +5, but the valence +4 is preferred in solid neptunium compounds. Neptunium metal is very reactive. Ions of neptunium are prone to hydrolysis and formation of coordination compounds.