1946/10/10 by John R. P. Arnold, W. F. Libby · 1 citation
Materials Science · Physics and Astronomy · Chemistry · #Graphite, nuclear technology, radiation studies #Nuclear Physics and Applications #Graphite #Oxygen #Pile #Radiochemistry #Chemistry #Irradiation #Carbon fibers #Lattice (music) #Materials science #Analytical Chemistry (journal) #Mineralogy #Geology #Chromatography #Physics #Nuclear physics #Composite material #Organic chemistry
paper · pdf · doi:10.2172/4350390
openalex publication_date 1946/10/10 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/04
Samples of pile graphite, irradiated in a test-hole at Hanford for 15 months, have been assayed for radioactive Csup14, yielding 0.38 ± 0.04 microcuries per gram. At this level of activity, the pile graphite contains very valuable amounts of Csup14. The relation between the above assay and the probable average assay of pile graphite is discussed, and it is concluded that the latter is almost certainly above 0.3 uc/ gram. Controlled oxidation of this graphite, either with oxygen at ~ 750°C, or with chromic acid "cleaning solution" at room temperature, yields early fractions which are highly enriched in Csup14. Concentrations of 5-fold with oxygen, and 50-fold with CROsub3, have been observed. The relation between the observed enrichment and the Wigner effect is discussed, and a mechanism accounting for the observations put forward. According to this, about 25% of the stable carbon atoms in the lattice have been displaced by Wigner effect, a large fraction of which have healed the migrating to crystal edges. All the Csup14 atoms have been displaced, and the same fraction of these migrate to the edges. The enrichment then results from surface oxidation, in the oxygen case. Predictions are made on the basis of this hypothesis. A technique of counting radioactive COsub2 in the gas phase is described.