Isotope reduction reactor

Now, GC-IRMS can be used to measure the nitrogen isotopic composition of individual compounds [657]. Measurement of nitrogen isotope ratios was described by Merritt and Hayes [639], who modified a GC-C-IRMS system by including a reduction reactor (Cu wire) between the combustion furnace and the IRMS, for reduction of nitrogen oxides and removal of oxygen. Preston and Slater [658] have described a less complex approach which provides useful data at lower precision. Similar approaches have been described by Brand et al. [657] and Metges et al. [659]. More recently Macko et al. [660] have described a procedure, which permits GC-IRMS determination of 15N/14N ratios in nanomole quantities of amino acid enantiomers with precision of 0.3-0.4%o. A key step was optimization of the acylation step with minimal nitrogen isotope fractionation [660]. 

Uranium metal was used as fuel in early types of reactors. UFe, sublimating at 56 °C, is used to separate the isotopes U and U. After isotope separation, UO2 may be obtained from UFg by hydrolytic decomposition, precipitation of U as ADU and heating, and uranium metal may be produced by reduction with hydrogen to UF4 and further reduction with Ca. Handling of enriched uranium compounds requires small-scale operations with amounts of the order of 1 to 10 kg, depending on the conditions, to exclude criticality. 

Canfield (2001) undertook a comprehensive study of isotope fractionation by natural populations of SRB in sediment from a small marine lagoon located off the Danish coast. He used a flowthrough reactor and controlled the sulfate concentration, temperature, and ultimately the nature of the organic substrate. High fractionations of 30%o and 40%o were found when the SRB metabolized with natural organic substrate at environmental temperatures of 25 °C. The experiment continued until depletion of the natural substrate occurred, and then acetate, ethanol, and lactate were added from an external source. The isotopic fractionations observed ranged from l%c to 40%o, and increased fractionations correlated with decreased rates of sulfate reduction as noted in the laboratory studies. An exception occurred at low temperatures, where decreased reduction rates... 

Derivation Multiple neutron capture in plutonium in nuclear reactors, plutonium isotopes yield241 Am and 243Am on (3 decay. The metal is obtained by reduction of the trifluoride with barium in a vacuum at 1200C. 

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