A fission track method for the determination of uranium in natural waters for geochemical exploration

CIM Bulletin, Vol. 76, No. 852, 1983

R.H. McCORKELL, Bondar-Clegg and Company Ltd., Ottawa, Canada

Sample drops were evaporated on Lexan disks on which fission tracks were etched and counted after neutron irradiation. [U] < 0.01 ppb could be measured. This method is rapid, cheap, simple and accurate when sufficient control and checking is possible, but several types of error were encountered in its use, the natures and sources of which were investigated but not always determined. The most troublesome were "annealing" processes which sometimes altered the fission tracks so that they were not fully revealed, or acquired varying appearances, after etching. Several different annealing processes seemed to exist and seemed to be produced by alteration of the Lexan surface by dissolved components in the solutions and, perhaps, by radiation and local heating during neutron irradiation. The appearances of the etched tracks varied with the natures of the droplet solutions even when annealing appeared to be absent, and for this reason, standards are best prepared by additions of known amounts of U to sample solutions. Contamination of sample droplets by U-containing dust from the air is best avoided by preparing the disks away from areas where other U-analysis is being carried out.
Mots Clés: Geochemical exploration, Uranium exploration, Fission-track, Chemical analysis, Uranium analysis, Water analysis, Natural waters.