RADIOCARBON FROM PILE GRAPHITE CHEMICAL METHODS FOR ITS CONCENTRATIONS

Technical Report · Thu Oct 10 00:00:00 EST 1946

DOI:https://doi.org/10.2172/4350390· OSTI ID:4350390

Arnold, J R; Libby, W F

Samples of pile graphite, irradiated in a test-hole at Hanford for 15 months, have been assayed for radioactive C{sup14}, yielding 0.38 ± 0.04 microcuries per gram. At this level of activity, the pile graphite contains very valuable amounts of C{sup14}. 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 C{sup14}. Concentrations of 5-fold with oxygen, and 50-fold with CRO{sub3}, 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 C{sup14} 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 CO{sub2} in the gas phase is described.

• Research Organization: Argonne National Lab., Lemont, Ill.
• Sponsoring Organization: US Atomic Energy Commission (AEC)
• DOE Contract Number: W-31109-ENG-38
• NSA Number: NSA-11-008308
• OSTI ID: 4350390
• Report Number(s): CC-3643
• Country of Publication: United States
• Language: English

Related Subjects

CARBON 14
CARBON DIOXIDE
CHEMISTRY
CHROMIUM OXIDES
CONTROL
COUNTERS
DIFFUSION
ENRICHMENT
GASES
GRAPHITE
IRRADIATION
LABELLED COMPOUNDS
MEASURED VALUES
OXIDATION
OXYGEN
QUALITATIVE ANALYSIS
RADIATIONS
REACTORS
SURFACES
WIGNER EFFECT