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The Discovery and First Isolation of Plutonium

The Discovery and First Isolation of Plutonium. (and other heavy metal excursions) By John Langridge Department of Chemistry, The University of North Texas jlangridge@sbcglobal.net. Significance of Pu Discovery 1,2.

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The Discovery and First Isolation of Plutonium

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  1. The Discovery and First Isolation of Plutonium (and other heavy metal excursions) By John Langridge Department of Chemistry, The University of North Texas jlangridge@sbcglobal.net

  2. Significance of Pu Discovery1,2 • First time a synthetic element had ever been isolated in weighable quantities • First time weighable quantities of “transmutation products” created in particle accelerator • End of WW2 in Pacific theater • Development of beautiful, ultra - micro scale Chemistry

  3. Importance of Understanding Plutonium Chemistry Today5 • Waste management issues and environmental impact • Weapons programs • Nuclear Energy • Large scale electricity generation • Space travel (238) • Pacemakers (238)

  4. How was Plutonium Created? • 5 kg uranyl nitrate hexahydrate (U238) + 12 Mev Neutrons from the Berkeley 60-inch cyclotron in (d,n) reaction with Be1

  5. The Post-Irradiation Product • Mixture of Pu, Np, U, and other fission products1 • Separated and concentrated using lanthanides in sulfuric acid solution followed by series of “fluoride cycles”1 • Concentration occurred in Berkeley while isolation occurred in Chicago1

  6. Concentration and Isolation1 Part1: Fluorides  Sulfates • Evaporation to half original volume • 2 mL 27M HF • 5M KF added to precipitate the lanthanide and Plutonium Fluorides • Resulting precipitate contributed 70K cpm vs. 300 cpm remaining in solution • Sulfuric acid + heat + precipitate  soluble lanthanide and Plutonium sulfates

  7. Concentration and Isolation1 Part2: Sulfates  oxidized Pu soluble Fluoride • 2 mL 2M nitric acid to dissolve the sulfate • Silver Oxide oxidizes Plutonium to Fluoride soluble state • 2M HF precipitates the lanthanides as insoluble Fluorides leaving Pu in solution as soluble Fluoride (95% efficient) • Wax coated syringes and glassware utilized

  8. Concentration and Isolation1Part 3 soluble fluorideinsoluble fluoride • Fluoride solution evaporated in sulfuric acid • Reduction to insoluble Fluoride • Fluoride cycle begins again using higher purity reagents • Results in higher purity product

  9. The First Isolated Sample2 • Approximately 1 µg Fluoride • Magnified 30 X • Solubility 5mg/L through specific activity analysis (assumed 30k year t1/2)

  10. What was learned?2 • Lower oxidation state carried by fluorides of lanthanide (La and Ce) • Lower state  Higher state using silver ions • Higher state  Lower state using SO2 or Br- • Pu(aq) + (Zn)  Pu(s)  Reduction doesn’t occur • Multiple redox cycles can remove all but contaminants most like Pu (Sm, for example) • Specific activity can accurately estimate mass and solubility • New methods for ultra micro-chemical analysis

  11. 95 Americium (1944) 96 Curium (1944) 97 Berkelium (1949) 98 Californium (1950) 99 Einsteinium (1952) 100 Fermium (1952) 101 Mendelevium (1955) 102 Nobelium (1956) 103 Lawrencium (1961) 104 Rutherfordium (1966) 105 Dubnium (1968) 106 Seaborgium (1974) 107 Bohrium (1981) 108 Hassium (1984) 109 Meitnerium (1982) 110 Darmstadtium (1994) 111 Roentgenium (1994) 112 Copernicium (1996) Discoveries that followed3

  12. State of the Art: Gas flow transport and detection and “online” Chemistry4

  13. References • Cunningham, B.B. and Werner, L.B. “The First Isolation of Plutonium.” Journal of the American Chemical Society 71.5 (1949): 1521-1524. Print • Seaborg, Glenn T. “Forty Years of Plutonium Chemistry: The Beginnings.” Washington: ACS Symposium Series American Chemical Society, 1983. 1-22. Print. • “Transuranium Elements." Encyclopedia Britannica Online. Encyclopedia Britannica, 2010. Thursday, November 18, 2010. • Eichler, R. et al. “Chemical characterization of element 112." Nature 447.3 (2007): 72-75. Print. • Clark, David. “The Chemical Complexities of Plutonium.” Los Alamos Science 20.1 (2000):365-381. Online

  14. Development of Ultra-micro-scale hardware1

  15. Development of Ultra-micro-scale hardware1

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