Authors:D. Brown, K. Glover, M. King, G. Phillips, F. Rogers, and R. Wiltshire
The half-life of239Pu has been determined by specific activity measurements on solutions prepared from the stoichiometric compounds Cs2 PuCl6, using plutonium 99.03% enriched in239Pu. The value obtained is 24,088 years, to which a realistic uncertainty of ±51 years is ascribed. This result is discussed
in relationship to all previously reported values.
Authors:K. Abel, A. Schilk, D. Brown, M. Knopf, R. Thompson, and R. Perkins
A large area beta scintillation detector has been developed which is currently capable of determining Sr-90/Y-90 contamination in surficial soils. The detector system employs scintillating fiber optic arrays, with active dimensions approximately 15 cm wide by 100 cm long, both ends of which are coupled to multiple photomultiplier tubes (PMTs). Electronic processing includes coincidence requirements to optimize sensitivity and selectivity for the 2.28 MeV (maximum) beta particle from Y-90. Low energy beta particles and gamma rays are discriminated against using double ended and multi-layer coincidence requirements. The detector system is personal-computer-software controlled and data restored in a format compatible with standard database software for ease of final data reduction. Experimental calibration studies have shown a linear response for Sr-90/Y-90 soil concentrations from 12 to over 500 pCi/g and a discrimination factor of 50 to 1 versus Cs-137.
Authors:R. J. Pillar, M. Ginic-Markovic, S. R. Clarke, A. K. Gibson, W. R. Bell, H. R. Brown, D. J. Willis, W. A. Renshaw, and J. G. Matisons
Summary This study investigates mechanisms of cold rolling oil removal from the surface of low-carbon steel. The removal process has been probed using thermogravimetric analysis techniques. A range of furnace atmospheres, from non-oxidizing through to highly oxidising, have been used to simulate the oil removal conditions in the industrial process. The activation energies of oil removal under each gas atmosphere have been determined by MTG and the Flynn-Wall-Ozawa method. The results show that a reducing atmosphere is the optimal environment for effective oil removal. Steel-oil surface interactions have also been investigated to show that the steel substrate catalyses oil removal.