Transcript The 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
[email protected]
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
2
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)
3
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
4
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
5
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
6
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
7
1
Isolation
Concentration and
Part 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
8
The First Isolated Sample2
Approximately 1 µg
Fluoride
Magnified 30 X
Solubility 5mg/L
through specific activity
analysis (assumed 30k
year t1/2)
9
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 BrPu(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
10
Discoveries that followed3
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)
11
State of the Art: Gas flow
transport and detection and
4
“online” Chemistry
12
References
1)
2)
3)
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.
4)
Eichler, R. et al. “Chemical characterization of element 112."
Nature 447.3 (2007): 72-75. Print.
5)
Clark, David. “The Chemical Complexities of Plutonium.” Los
Alamos Science 20.1 (2000):365-381. Online
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Development of Ultra-microscale hardware1
Development of Ultra-microscale hardware1