EFFECTS OF IONIZING RADIATION AND THERMAL TREATMENTS ON THE FATE OF RADIOBROMINE PRODUCED BY RADIATIVE NEUTRON CAPTURE IN COLID ORGANIC BROMIDES

Journal Article · Sun Apr 01 00:00:00 EST 1962 · Dissertation Abstr.

OSTI ID:4829885

Collins, K E

The effects of ionizing radiation and thermal treatments on the cheraical fate of Br/sup 82/ atoms produced in solid C/sub 2/Br/sub 6/ by the Br/ sup 81/(n, gamma )Br/sup 82/ process and the effects of thermal treatments on the fate of Br/sub 2/ produced in solid C/sub 2/Br/sub 6/ by ionizing radiation were investigated. The work was designed to clarify and extend the available information on the nature of radiation annealing and thermal annealing processes of radiohalogen atoms produced by the (n, gamma ) process in solid organic halides. The chemical fate of Br/sup 82/ atoms was measured by two types of determinations; the aqueous yield (the percentage of the Br/sup 82/ activity extractable into the aqueous phase from a solution of the crystals in an organic solvent) and the evaporation yield (the percentage of Br/sup 82/ activity evaporating from a solution of the crystals in liquid bromine). The results indicate that the aqueous extractable Br/sup 82/ was in the chemical form of Br/ sub 2/ and that the activity which remained in the residue crystals after the bromine evaporation was in the form of C/sub 2/Br/sub 6/. Thermal annealing appears to have occurred by the reaction of BrBr/sup 82/ with neighboring radicals or C/sub 2/Br/sub 4/ molecules to produce C/sub 2/Br/sub 5/Br/sup 82/. An additiona l unidentified fraction of the Br/sup 82/ evaporated with Br/sub 2/ but did not extract into the aqueous solution. As much as 10/sup 20/ ev g/sup -1/ of ionizing radiation from a Co/sup 60/ source, given either before or after neutron activation, did not appreciably alter the amount of aqueous extractable Br/sup 82/ from neutron irradiated C/sub 2/Br/sub 6/ if the samples were maintained at -196 deg C until analysis. However, ionizing radiation did affect the aqueous yield if given at O deg C after the neutron irradiation. Exposure to ionizing radiation either before or after neutron irradiation at -196 deg C or at O deg C affected the subse quent thermal annealing of the aqueous extractable Br/ sup 82/ species. These facts indicate that transitory intermediates produced by the gamma radiation can affect the fate of Br/sup 82/ present in the crystal and that relatively long-lived effects produced by the gamma irradiation are retained in the crystal and can migrate to affect the Br/sup 82/ when the crystal is heated. At least six different thermal annealing processes which reduced the aqueous yield were shown to occur in C/sub 2/Br/sub 6/ which had been irradiated with neutrons at -196 deg C. One of these which involved at least 27% of the Br/ sup 82/ activity, was complete within several seconds at O deg C and was independent of prior Co/sup 60/ irradiation of the C/sub 2/Br/sub 6/. The other five processes were indicated by analysis of kinetic data from isothermal annealing experiments at temperatures from 0 to 1OO deg C. One of these, occurring at 1OO deg C but not at 76.5 C was a second order process which was insensitive to a 40-fold variation in absorbed dose of ionizing radiation. It is tentatively concluded that this process involved combinations of fragments within the (n, gamma ) produced defects. Bromine was produced by Co/sup 60/ irradiation of C/sub 2/Br/sub 6/, the Gvalue being 0.3 molecules per 100 ev for an absorbed dose of 10/sup 20/ ev g/sup -1/. Thermal annealing caused the Br/sub 2/ to return to organic combination at rates similar to those observed for the thermal annealing of Br/sup 82/ produced in the crystals by the (n, gamma ) process. Thermal treatments at 45 deg C, 64.5 deg C and 76.5 deg resulted in the decrease of G(Br/sub 2/) to a plateau value of 0.09.

• Research Organization: Univ. of Wisconsin, Madison
• NSA Number: NSA-16-023733
• OSTI ID: 4829885
• Journal Information: Dissertation Abstr., Vol. Vol: 22; Other Information: Orig. Receipt Date: 31-DEC-62
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

CHEMISTRY
ACTIVATION
ANNEALING
ATOMS
BROMINATED HYDROCARBONS
BROMINE
BROMINE 81
BROMINE 82
CAPTURE
CHEMICAL REACTIONS
COBALT 60
CRYSTALS
DECOMPOSITION
DIFFUSION
DISTRIBUTION
ETHANE
ETHYLENE
EVAPORATION
FREE RADICALS
GAMMA RADIATION
GAMMA SOURCES
HALOGENS
HEAT TREATMENTS
HEATING
IONIZATION
IONIZING RADIATIONS
IRRADIATION
LABELLED COMPOUNDS
LIQUIDS
LOW TEMPERATURE
MEASURED VALUES
MOLECULES
NEUTRONS
NUCLEAR REACTIONS
ORGANIC BROMINE COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
QUANTITATIVE ANALYSIS
RADIATION CHEMISTRY
RADIATION DOSES
RADIOISOTOPES
SOLIDS
SOLUTIONS
SOLVENTS
TEMPERATURE
WATER
X RADIATION