Age determination of a 75Se gamma radiography source for nuclear forensics

Journal of Radioanalytical and Nuclear Chemistry - Two methods were used to evaluate the age of 75Se sealed source material. Both methods utilized gamma spectroscopy to determine the quantity of...     

The study of hydronium NASICON conductivity with deuterium

The ionic conductivity of the bulk phase of bonded hydronium NASICON (Hyceram^TM) was measured at equilibrium with an H₂O/N₂ and then a D₂O/N₂ atmosphere, each at 100% relative humidity and 75% relative humidity over the temperature range 25°C to 50°C. At 100% relative humidity and 25°C, the protonic system had a bulk conductivity of 5.0×10⁻⁴ S/cm and an activation energy of 17.3kJ/mole; the same sample, when deuterated, had a bulk conductivity of 2.2×10⁻⁴ S/cm and an activation energy of 19.3kJ/mole. At 75% relative humidity and 25°C, the conductivity of the protonated system decreased to 1.4×10⁻⁴S/cm with an activation energy of 24.1 kJ/mole. The deuterated sample at 75% relative humidity had a bulk conductivity of 5.4×10⁻⁵ S/cm with an activation energy of 26.0 kJ/mole. The isotope effect suggested a proton hopping (Grotthus) mechanism as the means by which the protons pass through the lattice.     

An alternative separation procedure for 90Sr age dating using DGA Resin

Journal of Radioanalytical and Nuclear Chemistry - The likelihood of an attack by a terrorist organization using a radiological dispersal device (RDD) is much higher than that of an attack with an...     

The analysis of protonically exchanged β″-alumina powder

The ion exchange behaviour of β″-alumina was studied using Instrumental Neutron Activation Analysis (INAA). It was discovered that approximately 10% of the original sodium remained unexchanged. This is consistent with previous studies in which it was found that 13 to 16% of the original sodium was non-labile. X-ray fluorescence (XRF) was also used to confirm the INAA results.     

The effect of absorbed water on hydronium NASICON and Hyceram

The bulk resistance of bonded hydronium NASICON, (Hyceram^TM), was studied at 45°C in relative humidities ranging from 40% to 100% in both H₂O/N₂ and D₂O/N₂ atmospheres. The bulk resistance was found to increase exponentially with decreasing relative humidity. In addition, the isotope effect remained close to 2.2 over the range of relative humidities tested; therefore proton hopping (Grotthus mechanism) was shown to be the dominant conduction mechanism from saturation down to 40% relative humidity. Saturated and desiccated samples of hydronium NASICON powder were prepared for X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The XRD patterns revealed that the change in the lattice plane spacings arising from the absorption of water was negligible. TGA showed that the x=1.5 form of hydronium NASICON contained at least 1.5 moles of absorbed water per mole of NASICON when saturated. In addition, the absorbed water was shown to be weakly held by the lattice since its evolution from the saturated sample was rapid. These XRD and TGA results suggested that the molecules of absorbed water occupy lattice sites which might afford considerable freedom of rotational and translational motion.