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126-411: 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

252-504: A cyclotron . Tentatively called " radium F ", polonium was discovered by Marie and Pierre Curie in July 1898, and was named after Marie Curie's native land of Poland ( Latin : Polonia ). Poland at the time was under Russian , German , and Austro-Hungarian partition , and did not exist as an independent country. It was Curie's hope that naming the element after her native land would publicize its lack of independence. Polonium may be

378-444: A metalloid ) with no stable isotopes , polonium is a chalcogen and chemically similar to selenium and tellurium , though its metallic character resembles that of its horizontal neighbors in the periodic table : thallium , lead , and bismuth . Due to the short half-life of all its isotopes, its natural occurrence is limited to tiny traces of the fleeting polonium-210 (with a half-life of 138 days) in uranium ores , as it

504-489: A neutron trigger or initiator for nuclear weapons and for inspections of oil wells. About 1500 sources of this type, with an individual activity of 1,850 Ci (68 TBq), had been used annually in the Soviet Union. Polonium was also part of brushes or more complex tools that eliminate static charges in photographic plates, textile mills, paper rolls, sheet plastics, and on substrates (such as automotive) prior to

630-449: A "general license", which means that a buyer need not be registered by any authorities. Polonium needs to be replaced in these devices nearly every year because of its short half-life; it is also highly radioactive and therefore has been mostly replaced by less dangerous beta particle sources. Tiny amounts of Po are sometimes used in the laboratory and for teaching purposes—typically of the order of 4–40 kBq (0.11–1.08 μCi), in

756-400: A ' fizzle yield ', well below the design specification. If it occurs too late, the core will have begun to expand and disassemble into a less-dense state, leading to a lowered yield (less of the core material undergoes fission) or no yield at all (the core is no longer a critical mass). Therefore, low spontaneous neutron emission of the pit material is crucial. For boosted fission weapons ,

882-590: A NRC Exempt Quantity, which may be held without a radioactive material license. Polonium and its compounds must be handled with caution inside special alpha glove boxes , equipped with HEPA filters and continuously maintained under depression to prevent the radioactive materials from leaking out. Gloves made of natural rubber ( latex ) do not properly withstand chemical attacks, a.o. by concentrated nitric acid (e.g., 6 M HNO 3 ) commonly used to keep polonium in solution while minimizing its sorption onto glass. They do not provide sufficient protection against

1008-402: A blue glow which is caused by ionisation of the surrounding air. About one in 100,000 alpha emissions causes an excitation in the nucleus which then results in the emission of a gamma ray with a maximum energy of 803 keV. Polonium is a radioactive element that exists in two metallic allotropes . The alpha form is the only known example of a simple cubic crystal structure in

1134-591: A cascading (α,n) reaction can also be induced to produce Po in large quantities. The final purification is done pyrochemically followed by liquid-liquid extraction techniques. Polonium may now be made in milligram amounts in this procedure which uses high neutron fluxes found in nuclear reactors . Only about 100 grams are produced each year, practically all of it in Russia, making polonium exceedingly rare. This process can cause problems in lead-bismuth based liquid metal cooled nuclear reactors such as those used in

1260-580: A chemist and director of research at Monsanto in St. Louis , joined the National Defense Research Committee (NDRC) as the deputy chief of its Division 8, which was responsible for propellants, explosives and the like. Early in 1943, he traveled to the east with Richard C. Tolman , a member of the NDRC, and James B. Conant , the president of Harvard University and the chairman of the NDRC, to witness

1386-487: A continued supply of polonium for their manufacture, as their shelf life was only about 4 months. Later designs had shelf life as long as 1 year. The US government used Postum as a code name for polonium. Use of polonium for the neutron initiator was proposed in 1944 by Edward Condon , although polonium as an initiator was mentioned as a possibility in the " Los Alamos Primer " lectures given in April 1943. The initiator itself

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1512-523: A demonstration of a new underwater explosive. Conant and Tolman took the opportunity to quietly investigate Thomas' background. He was then invited to a meeting in Washington D.C., with Brigadier General Leslie R. Groves, Jr. , the director of the wartime Manhattan Project responsible for building an atomic bomb . When he got there, Thomas found Conant was also present. Groves and Conant were hoping to harness Thomas's industrial expertise. They offered him

1638-637: A direct hit from a 910-kilogram (2,000 lb) bomb, with protection against biological and chemical weapons , at a cost of $ 17,900,000. Responsibility for nuclear weapons production was transferred from the Manhattan Project to the Atomic Energy Commission in 1947, but work continued on the Mound Laboratories. The first building was completed in May 1948, and polonium processing commenced at

1764-522: A laundry. A new guardhouse was also built. To this was added two portable buildings in 1946. By 1944, space was running short, and Monsanto began negotiations to acquire the Runnymede Playhouse in the wealthy residential Dayton suburb of Oakwood . Built in 1927, the Playhouse was a leisure facility that included an outdoor swimming pool, a ballroom, a squash court, a tennis court with a cork floor and

1890-403: A lead-lined safe with doors on both sides containing tubes. They were also stored underwater on racks, and could be removed with tongs. A periscope allowed the identification markings on the slugs to be checked without removing them from the pool. By the end of 1946 Hanford was shipping material that contained up to 13,200 curies (490 TBq) per metric ton of bismuth. Bismuth was purchased from

2016-520: A lead-lined suitcase carried by a military courier. Regular shipments were made thereafter. Initiator testing at Los Alamos required more polonium than anticipated, and in December 1944, Oppenheimer was forced to ask Thomas if he could ship 20 curies (0.74 TBq) per month. The Dayton Project was able to do so. In February 1945, Thomas agreed to increase shipments to 100 curies (3.7 TBq) per month by June, and 500 per month by December. The total cost of

2142-809: A post as a deputy to Robert Oppenheimer , the director of the Los Alamos Laboratory in New Mexico, but he did not wish to move his family or give up his responsibilities at Monsanto. Instead, he accepted the role of coordinating the plutonium purification and production work being carried out at Los Alamos, the Metallurgical Laboratory in Chicago, Radiation Laboratory in Berkeley, and Ames Laboratory in Iowa. Chemistry and metallurgy at Los Alamos would be led by

2268-485: A result, polonium solutions are volatile and will evaporate within days unless sealed. At pH about 1, polonium ions are readily hydrolyzed and complexed by acids such as oxalic acid , citric acid , and tartaric acid . Polonium has no common compounds, and almost all of its compounds are synthetically created; more than 50 of those are known. The most stable class of polonium compounds are polonides , which are prepared by direct reaction of two elements. Na 2 Po has

2394-455: A single atom basis at STP ( space group Pm 3 m, no. 221). The unit cell has an edge length of 335.2 picometers ; the beta form is rhombohedral . The structure of polonium has been characterized by X-ray diffraction and electron diffraction . Po has the ability to become airborne with ease : if a sample is heated in air to 55 °C (131 °F), 50% of it is vaporized in 45 hours to form diatomic Po 2 molecules, even though

2520-516: A stage for community theater. It had showers with Italian marble and a 1 + 1 ⁄ 2 -story garage. The estate was owned by the Talbott Realty Company, which was controlled by Thomas's wife's family . The Talbotts were among the heirs of the Delco company, which was by then a part of General Motors . The Oakwood City Council wanted the Playhouse as a community center. Thomas appeared before

2646-417: A vast improvement over the yields from Port Hope's lead dioxide. Irradiated bismuth came from Clinton in the form of 30.5-by-9.5-by-9.5-centimeter (12 by 3.75 by 3.75 in) bricks that weighed about 26 kilograms (58 lb). They were shipped to Dayton by rail in wooden boxes, which were stored in a tile-lined cavity in the floor at Unit IV. These procedures were adequate because the quantity of polonium in

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2772-411: Is a layer of plating which in turn is plated with a material such as gold, which allows the alpha radiation (used in experiments such as cloud chambers) to pass while preventing the polonium from being released and presenting a toxic hazard. Polonium spark plugs were marketed by Firestone from 1940 to 1953. While the amount of radiation from the plugs was minuscule and not a threat to the consumer,

2898-549: Is a liquid at room temperature; however, this is due to hydrogen bonding. The three oxides, PoO , PoO 2 and PoO 3 , are the products of oxidation of polonium. Halides of the structure PoX 2 , PoX 4 and PoF 6 are known. They are soluble in the corresponding hydrogen halides, i.e., PoCl X in HCl, PoBr X in HBr and PoI 4 in HI. Polonium dihalides are formed by direct reaction of

3024-616: Is about 0.06 mg = 60 μg. In addition to the acute effects, radiation exposure (both internal and external) carries a long-term risk of death from cancer of 5–10% per Sv. The general population is exposed to small amounts of polonium as a radon daughter in indoor air; the isotopes Po and Po are thought to cause the majority of the estimated 15,000–22,000 lung cancer deaths in the US every year that have been attributed to indoor radon. Tobacco smoking causes additional exposure to polonium. The maximum allowable body burden for ingested Po

3150-444: Is about 4.5  Sv . The committed effective dose equivalent Po is 0.51 μSv/ Bq if ingested, and 2.5 μSv/Bq if inhaled. A fatal 4.5 Sv dose can be caused by ingesting 8.8 MBq (240 μCi), about 50  nanograms (ng), or inhaling 1.8 MBq (49 μCi), about 10 ng. One gram of Po could thus in theory poison 20 million people, of whom 10 million would die. The actual toxicity of Po

3276-536: Is approximately 0.2% of the abundance of radium. The amounts in the Earth's crust are not harmful. Polonium has been found in tobacco smoke from tobacco leaves grown with phosphate fertilizers. Because it is present in small concentrations, isolation of polonium from natural sources is a tedious process. The largest batch of the element ever extracted, performed in the first half of the 20th century, contained only 40 Ci (1.5 TBq) (9 mg) of polonium-210 and

3402-481: Is concentrated in these vital organs, it is a greater threat to life than the dose which would be suffered (on average) by the whole body if it were spread evenly throughout the body, in the same way as caesium or tritium (as T 2 O). Po is widely used in industry, and readily available with little regulation or restriction. In the US, a tracking system run by the Nuclear Regulatory Commission

3528-432: Is extremely dangerous to humans. Po is an alpha emitter that has a half-life of 138.4 days; it decays directly to its stable daughter isotope , Pb . A milligram (5  curies ) of Po emits about as many alpha particles per second as 5 grams of Ra , which means it is 5,000 times more radioactive than radium. A few curies (1 curie equals 37  gigabecquerels , 1 Ci = 37 GBq) of Po emit

3654-418: Is extremely dangerous, requiring specialized equipment (a negative pressure alpha glove box equipped with high-performance filters), adequate monitoring, and strict handling procedures to avoid any contamination. Alpha particles emitted by polonium will damage organic tissue easily if polonium is ingested, inhaled, or absorbed, although they do not penetrate the epidermis and hence are not hazardous as long as

3780-466: Is known, mostly restricted to dialkyl and diaryl polonides (R 2 Po), triarylpolonium halides (Ar 3 PoX), and diarylpolonium dihalides (Ar 2 PoX 2 ). Polonium also forms soluble compounds with some ligands , such as 2,3-butanediol and thiourea . Oxides Hydrides Halides Polonium has 42 known isotopes, all of which are radioactive . They have atomic masses that range from 186 to 227 u . Po (half-life 138.376 days)

3906-429: Is lower than these estimates because radiation exposure that is spread out over several weeks (the biological half-life of polonium in humans is 30 to 50 days ) is somewhat less damaging than an instantaneous dose. It has been estimated that a median lethal dose of Po is 15 megabecquerels (0.41 mCi), or 0.089 micrograms (μg), still an extremely small amount. For comparison, one grain of table salt

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4032-505: Is not a bone seeker like radium or plutonium, and is thus readily excreted in urine. Detection methods had already been developed, making it easy to track. The employee at Unit IV with the highest levels of polonium in her urine had contaminated her hair, and often held bobby pins in her mouth. George Koval was drafted into the United States Army in 1943, and was inducted into the Manhattan Project's Special Engineer Detachment. He

4158-404: Is only 1.1 kBq (30 nCi), which is equivalent to a particle massing only 6.8 picograms. The maximum permissible workplace concentration of airborne Po is about 10 Bq/m ( 3 × 10  μCi/cm ). The target organs for polonium in humans are the spleen and liver . As the spleen (150 g) and the liver (1.3 to 3 kg) are much smaller than the rest of the body, if the polonium

4284-454: Is only slightly soluble in alkalis . Polonium solutions are first colored in pink by the Po ions, but then rapidly become yellow because alpha radiation from polonium ionizes the solvent and converts Po into Po . As polonium also emits alpha-particles after disintegration so this process is accompanied by bubbling and emission of heat and light by glassware due to the absorbed alpha particles; as

4410-460: Is reported as 1.5 cm, or "about 2 cm". Uranium deuteride (UD 3 ) can be used for construction of a neutron multiplier. Boosted fission weapons and weapons using external neutron generators offer the possibility of variable yield , allowing selection of the weapon's power depending on the tactical needs. The polonium used in the urchin initiator was created at Oak Ridge National Laboratory and then extracted and purified as part of

4536-446: Is the penultimate daughter of natural uranium-238 . Though longer-lived isotopes exist, such as the 124 years half-life of polonium-209, they are much more difficult to produce. Today, polonium is usually produced in milligram quantities by the neutron irradiation of bismuth . Due to its intense radioactivity, which results in the radiolysis of chemical bonds and radioactive self-heating, its chemistry has mostly been investigated on

4662-415: Is the most widely available and is manufactured via neutron capture by natural bismuth . It also naturally occurs as a trace in uranium ores, as it is the penultimate member of the decay chain of U. The longer-lived Po (half-life 124 years, longest-lived of all polonium isotopes) and Po (half-life 2.9 years) can be manufactured through the alpha, proton, or deuteron bombardment of lead or bismuth in

4788-469: The American Smelting and Refining Company of the highest purity that it could produce. It was sent to Hanford, where it was canned, and placed inside a reactor for 100 days. The irradiated slugs were then shipped by road to Unit IV, where they were bathed in hydrochloric acid, which dissolved the aluminum. This formed an aluminum chloride solution that was disposed of, as it was highly radioactive due to

4914-553: The Dayton Project under the leadership of Charles Allen Thomas . The Dayton Project was one of the various sites comprising the Manhattan Project . In 1949, Mound Laboratories in nearby Miamisburg, Ohio opened as a replacement for the Dayton Project and the new home of nuclear initiator research & development. Polonium-210 was produced by neutron irradiation of bismuth . Production and research of polonium at Mound

5040-669: The Lunokhod 1 (1970) and Lunokhod 2 (1973) Moon rovers to keep their internal components warm during the lunar nights, as well as the Kosmos 84 and 90 satellites (1965). The alpha particles emitted by polonium can be converted to neutrons using beryllium oxide, at a rate of 93 neutrons per million alpha particles. Po-BeO mixtures are used as passive neutron sources with a gamma-ray -to- neutron production ratio of 1.13 ± 0.05, lower than for nuclear fission -based neutron sources. Examples of Po-BeO mixtures or alloys used as neutron sources are

5166-632: The Munroe effect , similar to a shaped charge , for fast and thorough mixing of the beryllium and polonium. As the Munroe effect is less reliable in linear geometry, later designs used a sphere with conical or pyramidal inner indentations instead of linear grooves. Some initiator designs omit the central sphere, being hollow instead. The advantage of a hollow design is possibly managing a smaller size while retaining reliability. The short half-life of polonium (138.376 days) required frequent replacement of initiators and

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5292-524: The Soviet Navy 's K-27 . Measures must be taken in these reactors to deal with the unwanted possibility of Po being released from the coolant. The longer-lived isotopes of polonium, Po and Po, can be formed by proton or deuteron bombardment of bismuth using a cyclotron . Other more neutron-deficient and more unstable isotopes can be formed by the irradiation of platinum with carbon nuclei. Polonium-based sources of alpha particles were produced in

5418-460: The Windscale Piles had been releasing polonium-210. The Windscale fire brought the need for testing of the land downwind for radioactive material contamination, and this is how it was found. An estimate of 8.8 terabecquerels (240 Ci) of polonium-210 has been made. It has also been suggested that Irène Joliot-Curie 's 1956 death from leukaemia was owed to the radiation effects of polonium. She

5544-407: The antifluorite structure, the polonides of Ca , Ba , Hg , Pb and lanthanides form a NaCl lattice, BePo and CdPo have the wurtzite and MgPo the nickel arsenide structure. Most polonides decompose upon heating to about 600 °C, except for HgPo that decomposes at ~300 °C and the lanthanide polonides, which do not decompose but melt at temperatures above 1000 °C. For example,

5670-410: The chain reaction in the compressed supercritical plutonium. Placing the polonium layer between two large masses of beryllium ensures contact of the metals even if the shock wave turbulence performs poorly. The 50 curies of polonium generated about 0.1 watts of decay heat , noticeably warming the small sphere. The grooves in the inner surface of the shell shaped the shock wave into jets by

5796-481: The decay chain of U ; Po and Po occur in the decay chain of U ; Po and Po occur in the decay chain of Th ; and Po and Po occur in the decay chain of Np . (No primordial Np survives, but traces of it are continuously regenerated through (n,2n) knockout reactions in natural U.) Of these, Po is the only isotope with a half-life longer than 3 minutes. Polonium can be found in uranium ores at about 0.1 mg per metric ton (1 part in 10 ), which

5922-546: The gun-type Little Boy and the implosion-type Fat Man used in the atomic bombings of Hiroshima and Nagasaki respectively. The fact that polonium was used as an initiator was classified until the 1960s, but George Koval , a technician with the Manhattan Project's Special Engineer Detachment , penetrated the Dayton Project as a spy for the Soviet Union . In December 1942, during World War II , Charles Allen Thomas ,

6048-405: The nuclear chain reaction at the moment of prompt-criticality to ensure that the weapon did not fizzle . 'Urchin' was used in early U.S. weapons; subsequent U.S. weapons utilized a pulse neutron generator for the same purpose. Much of the basic physics of polonium was classified until after the war. The fact that a polonium-beryllium (Po-Be) initiator was used in the gun-type nuclear weapons

6174-693: The Dayton Project on 10 November 1943. The first 230-kilogram (500 lb) batch was processed by 8 December, which made 30 microcuries (1.1  MBq ) of polonium available for experiments a week later. Three processes were investigated for extracting the polonium from the ore. J. H. Dillon of the Firestone Tire and Rubber Company had patented a process in which the lead oxide was dissolved in hydrochloric acid : The polonium could then be deposited on copper or nickel sheets. This required large-scale glass-lined equipment not available in Dayton, but available at

6300-507: The Dayton Project up to the end of 1946 was $ 3,666,507 ($ 57.3 million in today's dollars). Dayton Project employees were not allowed to eat or smoke in processing areas, and had to scrub their hands before leaving these areas. The chemists wore protective gear, with surgical, cloth and rubber gloves worn in three layers. When leaving for lunch or at the end of the shift, they had to wash their hands with dilute hydrochloric acid, dilute Clorox , and soap. The radioactive residue on their hands

6426-520: The Dayton Project was located in a populated, urban area. It ran from 1943 to 1949, when the Mound Laboratories were completed in nearby Miamisburg, Ohio , and the work moved there. The Dayton Project developed techniques for extracting polonium from the lead dioxide ore in which it occurs naturally, and from bismuth targets that had been bombarded by neutrons in a nuclear reactor . Ultimately, polonium-based neutron initiators were used in both

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6552-415: The Dayton Project, as they had short half-lives, and would become harmless during the slugs' cooling off period in water at Hanford; but iron could form iron-59, which had a half-life of 45 days, and produced gamma radiation. The slugs were therefore shipped in casks, each of which contained several tubes which held the slugs. The spaces between the tubs was filled with lead. At Dayton, the slugs were stored in

6678-513: The Monsanto B plant in Monsanto, Illinois . After small-scale tests at Unit III revealed that the process was practical, some three tons of lead dioxide were sent to the B plant, and 2.50 curies (93 GBq) were recovered. Getting the polonium off the copper and nickel sheets proved more problematic. A second method attempted was a kiln process. The idea was to simply roast the lead dioxide and vaporize

6804-674: The Mound Laboratories in February 1949. Altogether, 14 major buildings were constructed with a total floor space of 34,000 square meters (366,000 sq ft) at a cost of $ 25.5 million. Due to fear of attack or sabotage, the former Scioto Laboratory Complex in Marion, Ohio , was acquired by the Atomic Energy Commission in 1948. It was maintained as a cold standby site until it was no longer needed in 1953. Unit I continued to be used by Monsanto as an administrative facility until 1988, when it

6930-518: The University of Rochester from 1944 to 1947, in order to study its biological behaviour. These studies were funded by the Manhattan Project and the AEC. Four men and a woman participated, all suffering from terminal cancers, and ranged in age from their early thirties to early forties; all were chosen because experimenters wanted subjects who had not been exposed to polonium either through work or accident. Po

7056-408: The action of methylcobalamin . This is similar to the way in which mercury , selenium , and tellurium are methylated in living things to create organometallic compounds. Studies investigating the metabolism of polonium-210 in rats have shown that only 0.002 to 0.009% of polonium-210 ingested is excreted as volatile polonium-210. The median lethal dose (LD 50 ) for acute radiation exposure

7182-527: The alpha particles remain outside the body and do not come near the eyes, which are living tissue. Wearing chemically resistant and intact gloves is a mandatory precaution to avoid transcutaneous diffusion of polonium directly through the skin . Polonium delivered in concentrated nitric acid can easily diffuse through inadequate gloves (e.g., latex gloves ) or the acid may damage the gloves. Polonium does not have toxic chemical properties. It has been reported that some microbes can methylate polonium by

7308-406: The application of coatings. Alpha particles emitted by polonium ionize air molecules that neutralize charges on the nearby surfaces. Some anti-static brushes contain up to 500 microcuries (20 MBq) of Po as a source of charged particles for neutralizing static electricity. In the US, devices with no more than 500 μCi (19 MBq) of (sealed) Po per unit can be bought in any amount under

7434-579: The area was decontaminated. As of 2017, it houses the Mound Advanced Technology Center. In 1996, the Department of Energy , which had succeeded the Atomic Energy Commission, decided that since the Dayton sites already had been decontaminated, they did not warrant inclusion in the Army Corps of Engineers' Formerly Utilized Sites Remedial Action Program (FUSRAP). The local community in Dayton

7560-537: The area. The first of these recruits commenced in August 1943, but few had any experience with radiochemistry . Numbers increased from 46 full-time employees at the end of 1943 to 101 at the end of 1944, 201 at the end of 1945, and 334 at the end of 1946, including 34 members of the Army's Special Engineer Detachment . Office space was initially found in the Monsanto offices at 1515 Nicholas Rd, which became known as Unit I. Unit II

7686-563: The atomic bombs. The Dayton Project began in 1943 when Monsanto 's Charles Allen Thomas was recruited by the Manhattan Project to coordinate the plutonium purification and production work being carried out at various sites. Scientists at the Los Alamos Laboratory calculated that a plutonium bomb would require a neutron initiator. The best-known neutron sources used radioactive polonium and beryllium , so Thomas undertook to produce polonium at Monsanto's laboratories in Dayton. While most Manhattan Project activity took place at remote locations,

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7812-425: The benefits of such plugs quickly diminished after approximately a month because of polonium's short half-life and because buildup on the conductors would block the radiation that improved engine performance. (The premise behind the polonium spark plug, as well as Alfred Matthew Hubbard 's prototype radium plug that preceded it, was that the radiation would improve ionization of the fuel in the cylinder and thus allow

7938-551: The bismuth was still fairly low, but starting in June 1945, the Dayton Project began receiving bismuth irradiated in the more powerful reactors at the Hanford Site in Washington, which now became the major source of supply. Even at Clinton, unprotected bismuth proved problematic when a brick broke apart and chips fell into containers of uranium slugs, and had to be hazardously separated by hand by project personnel. Bismuth slugs irradiated in

8064-482: The bombing of Hiroshima. The initiator used in the implosion design of the Fat Man bomb that was dropped on Nagasaki was code-named "urchin". In order to increase the efficiency of the explosion, the initiator had to emit a large number of neutrons in a few microseconds while the plutonium core was fully compressed. At the heart of the urchin was a solid beryllium sphere 0.4 centimeters (0.16 in) in diameter. This

8190-448: The bottom two floors were occupied, providing 560 square meters (6,000 sq ft) of laboratory space. Later, the third floor was taken over as well, providing another 280 square meters (3,000 sq ft). In May 1945, five additional temporary buildings were constructed on land leased from the Board of Education that housed offices, a cafeteria, locker rooms, a physics laboratory and

8316-399: The contamination from polonium ( diffusion of Po solution through the intact latex membrane, or worse, direct contact through tiny holes and cracks produced when the latex begins to suffer degradation by acids or UV from ambient light); additional surgical gloves are necessary (inside the glovebox to protect the main gloves when handling strong acids and bases, and also from outside to protect

8442-532: The council and assured them that it would not be damaged, although he could not disclose what he was intending to use it for. When Talbott Realty proved reluctant to sell, the United States Army Corps of Engineers condemned the property, which became Unit IV on 15 February 1944. A lease was signed on 10 March 1944, under which the Talbott Realty was paid $ 4,266.72 per annum for the property. The lease

8568-681: The development of techniques to industrially refine polonium for use with beryllium in the "urchin" internal neutron initiators . This effort became the Dayton Project. Thomas brought in key personnel from Monsanto's Thomas and Hochwalt Laboratories in Dayton, Ohio , including Caroll Hochwalt, James Lum and Nicholas Samaras. Thomas became Director of the Dayton Project, with Hochwalt as Assistant Project Director and Lum as Laboratory Director. They decided that about twelve chemists would be required, and Lum set about recruiting professors, graduate students and industrial chemists from universities and laboratories in

8694-454: The dimensions and mechanical configuration of the system ensuring proper mixing of the metals. Urchin was the code name for the internal neutron initiator used by the Los Alamos Laboratory as a neutron generating device to trigger the nuclear detonation of the earliest plutonium atomic bombs such as The Gadget and Fat Man , once the critical mass had been 'assembled' by the force of conventional explosives. The initiator used in

8820-436: The early devices, located at the center of the bomb's plutonium pit , consisted of a beryllium pellet and a beryllium shell with polonium between the two. The pellet, 0.8 cm in diameter, was coated with nickel and then a layer of gold . The beryllium shell was of 2 cm outer diameter with wall thickness of 0.6 cm. The inner surface of that shell had 15 concentric, wedge-shaped latitudinal grooves and was, like

8946-463: The effects of polonium on laboratory animals. Analysis of bioassay samples was carried out there to minimize the danger of polonium contamination of the samples. Few people had seen polonium before. It was a silvery metal. In a dark room, it gave off an eerie, purple glow. Polonium occurs naturally in various ores, and the lead dioxide residues from the refinery in Port Hope, Ontario , left over after

9072-455: The efficiency of a gun-type fission weapon , Oppenheimer gave approval on 15 March 1945 for initiators to be included in the Little Boy design. The initiators were tested to ensure they were rugged enough to handle being transported in an airplane and being accidentally dropped. Eventually, about forty initiators were dispatched to Tinian , where four were inserted into the bomb that was used in

9198-535: The elements or by reduction of PoCl 4 with SO 2 and with PoBr 4 with H 2 S at room temperature. Tetrahalides can be obtained by reacting polonium dioxide with HCl, HBr or HI. Other polonium compounds include the polonite , potassium polonite ; various polonate solutions; and the acetate , bromate , carbonate , citrate , chromate , cyanide, formate , (II) or (IV) hydroxide, nitrate , selenate , selenite , monosulfide, sulfate , disulfate or sulfite salts. A limited organopolonium chemistry

9324-670: The first element named to highlight a political controversy. This element was the first one discovered by the Curies while they were investigating the cause of pitchblende radioactivity . Pitchblende, after removal of the radioactive elements uranium and thorium , was more radioactive than the uranium and thorium combined. This spurred the Curies to search for additional radioactive elements. They first separated out polonium from pitchblende in July 1898, and five months later, also isolated radium . German scientist Willy Marckwald successfully isolated 3 milligrams of polonium in 1902, though at

9450-510: The form of sealed sources, with the polonium deposited on a substrate or in a resin or polymer matrix—are often exempt from licensing by the NRC and similar authorities as they are not considered hazardous. Small amounts of Po are manufactured for sale to the public in the United States as "needle sources" for laboratory experimentation, and they are retailed by scientific supply companies. The polonium

9576-480: The former Soviet Union . Such sources were applied for measuring the thickness of industrial coatings via attenuation of alpha radiation. Because of intense alpha radiation, a one-gram sample of Po will spontaneously heat up to above 500 °C (932 °F) generating about 140 watts of power. Therefore, Po is used as an atomic heat source to power radioisotope thermoelectric generators via thermoelectric materials. For example, Po heat sources were used in

9702-414: The greenhouses was converted into a loading dock . The property was enclosed in a barbed wire fence that was floodlit by night, and patrolled around the clock by armed guards; there were 43 guards at Units III and IV. The Production Group began moving in on 1 June. Three guard houses were added, along with a wire fence. Changes to the site were minimized in order to make it easier to restore later. Because it

9828-410: The inner sphere, coated with gold and nickel. A small amount of polonium-210 (50 curies, 11 mg) was deposited in the grooves of the shell and on the central sphere: the layers of gold and nickel served to shield the beryllium from alpha particles emitted by the polonium. The whole urchin weighed about 7 grams and was attached to mounting brackets in a 2.5 cm diameter inner cavity in

9954-412: The iron impurities in the aluminum. The bismuth slugs were then dissolved in aqua regia . This was too weak for electroplating the polonium, so the nitric acid was removed, and then the polonium deposited on bismuth by adding powdered bismuth. This resulted in a 100–1 concentration. This could then be repeated by dissolving in aqua regia again to achieve a 1000–1 concentration. This was again dissolved, and

10080-503: The lease on Unit IV, the former Runnymede Playhouse, specified that it was to be returned, it was deemed to be too contaminated. The building was demolished in February 1950. The cobblestones in the driveway were removed and taken away, along with 2.1 meters (7 ft) of earth from under the house. The excavation was filled in, and the site was returned to the Talbott family, who were paid $ 138,750 in compensation. As of 2017, all that remains of

10206-480: The melting point of polonium is 254 °C (489 °F) and its boiling point is 962 °C (1,764 °F). More than one hypothesis exists for how polonium does this; one suggestion is that small clusters of polonium atoms are spalled off by the alpha decay. The chemistry of polonium is similar to that of tellurium , although it also shows some similarities to its neighbor bismuth due to its metallic character. Polonium dissolves readily in dilute acids but

10332-530: The motor to fire more quickly and efficiently.) Polonium can be hazardous and has no biological role. By mass, polonium-210 is around 250,000 times more toxic than hydrogen cyanide (the LD 50 for Po is less than 1 microgram for an average adult (see below) compared with about 250 milligrams for hydrogen cyanide ). The main hazard is its intense radioactivity (as an alpha emitter), which makes it difficult to handle safely. Even in microgram amounts, handling Po

10458-523: The only polonium produced in this manner was in cyclotrons , but the Manhattan Project's development of nuclear reactors offered the prospect of producing large amounts of polonium in this manner: A metric ton of bismuth irradiated in the Manhattan Project's X-10 Graphite Reactor at the Clinton Engineer Works in Oak Ridge, Tennessee , contained 32 to 83 curies (1.2 to 3.1 TBq) of polonium,

10584-473: The operator hands against Po contamination from diffusion, or direct contact through glove defects). Chemically more resistant, and also denser, neoprene and butyl gloves shield alpha particles emitted by polonium better than natural rubber. The use of natural rubber gloves is not recommended for handling Po solutions. Despite the element's highly hazardous properties, circumstances in which polonium poisoning can occur are rare. Its extreme scarcity in nature,

10710-541: The original playhouse is a brass doorknob and part of the greenhouse roof, which are part of the collection of the Mound Science and Energy Museum. Private residences now occupy the site. The Dayton Warehouse was decontaminated in 1950 and returned to its owners. The Mound Laboratories continued to produce polonium initiators until 1969. Polonium continued to be produced there for commercial sales and use in satellites until 1972. The laboratories were decommissioned in 1993, and

10836-400: The outer surface was coated in gold and 30 curies (1.1 TBq) of polonium. The 2.0-centimeter (0.79 in) initiator, which was hot to the touch, fitted neatly inside the 20-millimeter (0.8 in) hole in the center of the plutonium pit. By 1945, the Dayton Project had assumed such importance that the Manhattan Project decided to make it into a permanent facility. The original intention

10962-488: The pit. When the shock wave from the implosion of the plutonium core arrives, it crushes the initiator. Hydrodynamic forces acting on the grooved shell thoroughly and virtually instantly mix the beryllium and polonium, allowing the alpha particles from the polonium to impinge on the beryllium atoms. Reacting to alpha particle bombardment, the beryllium atoms emit neutrons at a rate of about 1 neutron every 5–10 nanoseconds (See Beryllium ). These neutrons trigger

11088-418: The polonide of praseodymium (PrPo) melts at 1250 °C, and that of thulium (TmPo) melts at 2200 °C. PbPo is one of the very few naturally occurring polonium compounds, as polonium alpha decays to form lead . Polonium hydride ( PoH 2 ) is a volatile liquid at room temperature prone to dissociation; it is thermally unstable. Water is the only other known hydrogen chalcogenide which

11214-637: The polonium and beryllium mixed. The production of the beryllium-polonium TOM initiators ended in 1953. The initiators were replaced with a different design, which slightly reduced the weapon yield but its longer shelf life reduced the complexity of the logistics. The sealed neutron initiator , brought into inventory in late 1954, still required a periodic disassembly to access its capsule for maintenance checks. The capsules were phased out completely in 1962. Urchin style initiators were later superseded by other means of generating neutrons such as pulsed neutron emitters that do not use polonium. Using tritium with

11340-407: The polonium electroplated on platinum foils. The main problem with the process was that it required glass-lined containers due to the aqua regia, and mechanisms for safe handling of the radioactive material. The Dayton Project explored alternative purification methods that were found to be workable, but less efficient or safe. The first consignment of polonium left for Los Alamos on 15 March 1944 in

11466-431: The polonium. The problem was that lead dioxide slagged at 700 °C (1,292 °F), which was too low for the process to work. So lead orthophosphate was tried, which slagged at 900 °C (1,650 °F). This was made by mixing the lead dioxide with phosphoric acid . Experiments showed that the polonium vaporized well when the lead orthophosphate was heated to 750 °C (1,380 °F) for four hours. Unfortunately,

11592-435: The previous day, he had been working for five hours in an area in which, unknown to him, a capsule containing Po had depressurised and begun to disperse in aerosol form. Over this period, his total intake of airborne Po was estimated at 0.11 GBq (almost 25 times the estimated LD 50 by inhalation of 4.5 MBq). Despite treatment, his condition continued to worsen and he died 13 days after the exposure event. From 1955 to 1957

11718-589: The process did not proceed beyond the pilot stage because a better source of polonium became available. The lead dioxide was not purchased by the Manhattan Project, and early in the war had been acquired by the Canadian government. In June 1945, the lead was precipitated as a lead carbonate slurry, and shipped to the Manhattan District's Madison Square area to be dried and returned to Canada. Polonium could also be produced by neutron irradiation of bismuth . In 1943

11844-604: The process then ran into problems with dust and other foreign matter, and with contamination of the personnel and equipment involved. The third method involved dissolving the lead dioxide in a mixture of concentrated nitric acid and hydrogen peroxide : This proved to be the best way to separate the polonium from the lead dioxide, although there were problems with the precipitation of various contaminants, including iron and aluminum . Although about 32 metric tons (35 short tons) of lead dioxide were treated with nitric acid, and about 40 curies (1.5 TBq) of polonium were produced,

11970-473: The reactors at Hanford were therefore canned in aluminium. The canned slugs were 3.8 centimeters (1.5 in) in diameter, and 10 or 20 centimeters (4 or 8 in) long. The problem was that the aluminium contained impurities such as iron , manganese , copper , lead, tin , zinc , silicon , titanium , nickel , magnesium , chromium , vanadium , bismuth and gallium , and when irradiated, these could form radioactive isotopes. Most were of little concern for

12096-406: The removal of uranium and radium, were estimated to contain 0.2 to 0.3 milligrams (0.0031 to 0.0046  gr ) of polonium per metric ton. A curie of polonium weighs about 0.2 milligrams (0.0031 gr). Port Hope was already under contract from the Manhattan Project for the supply and refining of uranium ore. The first 3,290 kilograms (7,250 lb) of radioactive lead dioxide was delivered to

12222-575: The secret installation. In 2007 Russian President Vladimir Putin posthumously awarded Koval a gold star, making him a hero of the Russian Federation for his work as the GRU spy "Delmar". Russian officials stated that the initiator for their Joe-1 bomb had been "prepared to the recipe provided by Delmar". The fact that polonium was used as an initiator remained classified until the 1960s. After Leonard I. Schiff calculated that an initiator might improve

12348-486: The short half-lives of all its isotopes, the specialised facilities and equipment needed to obtain any significant quantity, and safety precautions against laboratory accidents all make harmful exposure events unlikely. As such, only a handful of cases of radiation poisoning specifically attributable to polonium exposure have been confirmed. In response to concerns about the risks of occupational polonium exposure, quantities of Po were administered to five human volunteers at

12474-640: The size of the centrally placed initiator is critical and has to be as small as possible. The use of an external neutron source allows more flexibility, such as variable yields. The usual design is based on a combination of beryllium -9 and polonium-210 , separated until activation, then placed in intimate contact by the shock wave. Polonium-208 and actinium-227 were also considered as alpha sources. The isotope used must have strong alpha emissions and weak gamma emissions, as gamma photons can also knock neutrons loose and cannot be so efficiently shielded as alpha particles. Several variants were developed, differing by

12600-468: The tests did not include bone marrow. Sadeh, one of his students, and two colleagues died from various cancers over the subsequent few years. The issue was investigated secretly, but there was never any formal admission of a connection between the leak and the deaths. The Church Rock uranium mill spill July 16, 1979 is reported to have released polonium-210 . The report states animals had higher concentrations of lead-210, polonium-210 and radium-226 than

12726-424: The time he believed it was a new element, which he dubbed "radio-tellurium", and it was not until 1905 that it was demonstrated to be the same as polonium. In the United States, polonium was produced as part of the Manhattan Project 's Dayton Project during World War II . Polonium and beryllium were the key ingredients of the ' Urchin ' initiator at the center of the bomb's spherical pit . 'Urchin' initiated

12852-402: The tissues from control animals. Neutron initiator One of the key elements in the proper operation of a nuclear weapon is initiation of the fission chain reaction at the proper time. To obtain a significant nuclear yield, sufficient neutrons must be present within the supercritical core at the right time. If the chain reaction starts too soon (" predetonation "), the result will be only

12978-638: The trace scale only. Polonium was discovered on July 18, 1898 by Marie Skłodowska-Curie and Pierre Curie , when it was extracted from the uranium ore pitchblende and identified solely by its strong radioactivity: it was the first element to be discovered in this way. Polonium was named after Marie Skłodowska-Curie's homeland of Poland, which at the time was partitioned between three countries. Polonium has few applications, and those are related to its radioactivity: heaters in space probes , antistatic devices , sources of neutrons and alpha particles , and poison (e.g., poisoning of Alexander Litvinenko ). It

13104-474: The youthful Joseph W. Kennedy . At Los Alamos, physicist Robert Serber proposed that instead of relying on spontaneous fission, the chain reaction inside the atomic bomb should be triggered by a neutron initiator . The best-known neutron sources were radium - beryllium and polonium -beryllium. The latter was chosen, as polonium has a 138-day half-life , which made it intense enough to be useful but not long-lived enough to be stockpiled. Thomas took charge of

13230-445: Was gold -plated and coated with 20 curies (0.74 TBq) of polonium. The gold kept the polonium's alpha particles from striking the beryllium. This fitted inside two beryllium hemispheres with 15 parallel grooves cut into the inner surface. These grooves converted the shock wave of the implosion into jets that shattered the spheres and caused the beryllium and polonium to mix and emit neutrons. The hemispheres were nickel-plated and

13356-479: Was accidentally exposed in 1946 when a sealed capsule of the element exploded on her laboratory bench. As well, several deaths in Israel during 1957–1969 have been alleged to have resulted from Po exposure. A leak was discovered at a Weizmann Institute laboratory in 1957. Traces of Po were found on the hands of Professor Dror Sadeh, a physicist who researched radioactive materials. Medical tests indicated no harm, but

13482-525: Was added to the design as an afterthought and was not essential for the weapon's function. An improved construction of the initiator, probably based on conical or pyramidal indentations, was proposed in 1948, put into production by Los Alamos in January 1950, and tested in May 1951. The TOM design used less polonium, as the number of neutrons per milligram of polonium was higher than of the Urchin. Its outer diameter

13608-421: Was based on the same principle as the Urchin. It is believed the polonium was deposited on lotus -shaped platinum gauze to maximize its surface and enclosed in a tantalum sphere surrounded by uranium shell with embedded beryllium pellets. According to other sources, the design was yet more similar to the Urchin, with a beryllium shell shaped to create beryllium jets upon implosion. The initiator outer diameter

13734-591: Was classified until the 1960s. The Atomic Energy Commission and the Manhattan Project funded human experiments using polonium on five people at the University of Rochester between 1943 and 1947. The people were administered between 9 and 22 microcuries (330 and 810  kBq ) of polonium to study its excretion . Polonium is a very rare element in nature because of the short half-lives of all its isotopes. Nine isotopes, from 210 to 218 inclusive, occur in traces as decay products : Po, Po, and Po occur in

13860-636: Was concerned that the cleanup did not meet 21st-century environmental standards. Therefore, the state of Ohio asked the United States Congress to have the Army Corps of Engineers conduct a review. This was carried out in 2004 and 2005. The review concluded that no radioactive contaminants were found that would warrant inclusion in FUSRAP. Polonium Polonium is a chemical element ; it has symbol Po and atomic number 84. A rare and highly radioactive metal (although sometimes classified as

13986-538: Was demolished. The land was sold to Quality Chemicals in 1992, and then to DuPont in 2002. Unit III, the former Bonebrake Theological Seminary, was decontaminated in 1950 and returned to the Dayton Board of Education. The original seminary building was subsequently demolished, but several structures remain from the Dayton Project. The site was listed on the National Register of Historic Places on 10 May 2006. Although

14112-408: Was designed by James L. Tuck , and its development and testing was carried out at Los Alamos National Laboratory in " Gadget " division's initiator group led by Charles Critchfield . A different initiator (code named ABNER ) was used for the Little Boy uranium bomb. Its design was simpler and it contained less polonium. It was activated by the impact of the uranium projectile to the target. It

14238-408: Was implemented in 2007 to register purchases of more than 16 curies (590 GBq) of polonium-210 (enough to make up 5,000 lethal doses). The IAEA "is said to be considering tighter regulations ... There is talk that it might tighten the polonium reporting requirement by a factor of 10, to 1.6 curies (59 GBq)." As of 2013, this is still the only alpha emitting byproduct material available, as

14364-490: Was in poor shape when the Dayton Project took it over, with many broken windows, and the staircase between the second and third floors was missing. New heating and lighting were installed, windows were replaced, new flooring was laid, and some rooms were re-plastered. A pair of guard houses known as buildings J and K were added, as was a chemical storage shed known as building F, and a wire fence. Laboratory activities were transferred there from Unit I on 25 September. Initially only

14490-484: Was initially assigned to the Clinton Engineer Works, where his job as a health physics officer gave him access to much of the site. He began passing secrets relating to the production of polonium at Oak Ridge to the Soviet Union through his GRU (Soviet military intelligence) handler code-named "Clyde". In 1945 Koval was transferred to Dayton. Again, his job as a health physics officer gave him wide access to

14616-444: Was initially up to 30 June 1944, but was then extended annually until 30 June 1949. The lease specified that the property would be returned in its original condition. Talbott Realty were told that the property would be used to produce training films. Remodeling began on 17 March 1944. The tennis courts were subdivided into multiple rooms. The ceiling was lowered, and heating, air conditioning and air filtration systems were added. One of

14742-409: Was injected into four hospitalised patients, and orally given to a fifth. None of the administered doses (all ranging from 0.17 to 0.30 μ Ci kg ) approached fatal quantities. The first documented death directly resulting from polonium poisoning occurred in the Soviet Union , on 10 July 1954. An unidentified 41-year-old man presented for medical treatment on 29 June, with severe vomiting and fever;

14868-466: Was located in a residential area, efforts were also made to minimize noise and other disruptions. In May 1945, Monsanto rented three floors of a warehouse at 601 East Third Street from General Electric . Initially it was used to receive and store equipment used by the Project. Later the fourth floor was used as office space, and a laboratory was established on the fifth floor where studies were carried out on

14994-446: Was measured with a special Geiger counter designed for the purpose by physicist John J. Sopka. No more than one thousand counts per minute per hand was permissible. They had to shower at the end of each day's work, and were subjected to weekly urine tests. Employees with elevated levels of polonium were not allowed in the processing areas. Working with polonium without spreading contamination proved to be almost impossible. Fortunately, it

15120-510: Was next to a state park containing a large prehistoric Indian burial mound , which ultimately gave the Mound Laboratories its name. It was initially known as Unit V. Monsanto began construction in May 1946, using the Detroit firm of Giffels and Vallet as architects, while the plant was built by the Maxon Construction of Dayton. The design called for an underground complex that could withstand

15246-406: Was obtained by processing 37 tonnes of residues from radium production. Polonium is now usually obtained by irradiating bismuth with high-energy neutrons or protons. In 1934, an experiment showed that when natural Bi is bombarded with neutrons , Bi is created, which then decays to Po via beta-minus decay. By irradiating certain bismuth salts containing light element nuclei such as beryllium,

15372-661: Was only 1 cm. The first live fire test of a TOM initiator occurred on 28-Jan-1951 during the Baker-1 shot of Operation Ranger . A series of calibration experiments for initiation time vs yield data of the TOM initiators was done during the Operation Snapper , during the Fox test on 25 May 1952. In 1974, India performed the Smiling Buddha nuclear test . The initiator, codenamed "Flower",

15498-493: Was phased out in 1971. Polonium from Dayton was used by the G Division of Los Alamos in initiator design studies at a test site in Sandia Canyon. The initiator group built test assemblies by drilling holes in large turbine ball bearings, inserting the active material, and plugging the holes with bolts. These test assemblies were known as screwballs . The test assemblies were imploded and their remains studied to examine how well

15624-492: Was rejected in favor of erecting a Quonset hut at Unit III. A laboratory site was found at 1601 W. First Street that had originally been constructed to house the Bonebrake Seminary . It was a three-story brick building built in 1879, and owned by the Dayton Board of Education, which used it as a warehouse. Monsanto leased the site on 15 October 1943, and began converting it into a laboratory known as Unit III. The building

15750-477: Was the Monsanto Rocket Propellant works off Betty Lane near Ohio State Route 741 . While it was administered by Monsanto, it was not used by the Dayton Project. The site handled explosives including ammonium nitrate and ammonium picrate , but no radioactive materials were handled there. Work at Unit II ceased in the fall of 1945. Consideration was given to using it in December 1946, but this proposal

15876-479: Was to move operations to Oak Ridge, but it was decided that a site near Dayton was preferable. Few of the scientific and technical staff wanted to move to Tennessee, and there were concerns about the dangers of polonium contamination at a plutonium processing site. A search for a suitable site began in early 1946, and one was found in Miamisburg, about 19 kilometers (12 mi) from Dayton. The 72-hectare (178-acre) site

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