For many years at LLNL, we have been developing time-correlated neutron detection techniques and algorithms for applications such as Arms Control, Threat Detection and Nuclear Material Assay. Many of our techniques have been developed specifically for the relatively low efficiency (a few percent) attainable by detector systems limited to man-portability. Historically, we used thermal neutron detectors (mainly {sup 3}He), taking advantage of the high thermal neutron interaction cross-sections. More recently, we have been investigating the use of fast neutron detection with liquid scintillators, inorganic crystals, and in the near future, pulse-shape discriminating plastics which respond over 1000 times faster (nanoseconds versus tens of microseconds) than thermal neutron detectors. Fast neutron detection offers considerable advantages, since the inherent nanosecond production time-scales of spontaneous fission and neutron-induced fission are preserved and measured instead of being lost by thermalization required for thermal neutron detectors. We are now applying fast neutron technology to the safeguards regime in the form of fast portable digital electronics as well as faster and less hazardous scintillator formulations. Faster detector response times and sensitivity to neutron momentum show promise for measuring, differentiating, and assaying samples that have modest to very high count rates, as well as mixed fission sources …

Achieving China’s goal of reducing its carbon intensity (CO{sub 2} per unit of GDP) by 40% to 45% percent below 2005 levels by 2020 will require the strengthening and expansion of energy efficiency policies across the buildings, industries and transport sectors. This study uses a bottom-up, end-use model and two scenarios -- an enhanced energy efficiency (E3) scenario and an alternative maximum technically feasible energy efficiency improvement (Max Tech) scenario – to evaluate what policies and technical improvements are needed to achieve the 2020 carbon intensity reduction target. The findings from this study show that a determined approach by China can lead to the achievement of its 2020 goal. In particular, with full success in deepening its energy efficiency policies and programs but following the same general approach used during the 11th Five Year Plan, it is possible to achieve 49% reduction in CO{sub 2} emissions per unit of GDP (CO{sub 2} emissions intensity) in 2020 from 2005 levels (E3 case). Under the more optimistic but feasible assumptions of development and penetration of advanced energy efficiency technology (Max Tech case), China could achieve a 56% reduction in CO{sub 2} emissions intensity in 2020 relative to 2005 with cumulative reduction of …

The ability of Nafion® membrane to absorb water rapidly and create a network of hydrated interconnected water domains provides this material with an unmatched ability to conduct ions through a chemically and mechanically robust membrane. The morphology and composition of these hydrated membranes significantly affects their transport properties and performance. This work demonstrates that differences in interfacial interactions between the membranes exposed to vapor or liquid water can cause significant changes in kinetics of water uptake. In-situ small-angle X-ray scattering (SAXS) experiments captured the rapid swelling of the membrane in liquid water with nanostructure rearrangement on the order of seconds. For membranes in contact with water vapor, morphological changes are four-orders-of-magnitude slower than in liquid water, suggesting that interfacial resistance limits the penetration of water into the membrane. Also, upon water absorption from liquid water, a structural rearrangement from a distribution of spherical and cylindrical domains to exclusively cylindrical-like domains is suggested. These differences in water-uptake kinetics and morphology provide a new perspective into Schroeder’s Paradox, which dictates different water contents for vaporand liquid-equilibrated ionomers at unit activity. The findings of this work provide critical insights into the fast kinetics of water absorption of Nafion membrane, which can aid in …