Use of Lubricants in the NIF

There are two principal concerns that govern the use of lubricants in NIF: (1) Airborne molecular contaminants (AMCs)--AMCs are known to seriously degrade the performance of sol-gel coated optics. AMCs are produced by the slow outgassing of residues (non-volatile residues or ''NVRs'') of high molecular weight compounds left on surfaces. Lubricants, particularly hydrocarbon lubricants, are a primary source of such NVRs. (2) Particulates--Particulates that accumulate on optical surfaces can cause permanent physical damage when exposed to high energy density laser light. Lubricant residues exposed to high energy density light will pyrolyze or decompose and produce carbon particulates. The NIF Approved Materials Database lists several lubricants that have been tested for use in NIF environments. Many of these lubricants were tested according to MELs 99-006 (oven outgassing test) or 99-007 (vacuum outgassing test). In these tests, the change in percent transmission of light through a sol-gel coated optic placed next to the sample under evaluation is used as the diagnostic. Samples that cause less than 0.1% change in optical transmission are deemed suitable for use inside beam enclosures. This testing, however, addresses only the concern associated with AMCs. To assess the issue of particle generation, a flashlamp or ''aerosol'' test is used. In this test a sample with residues is subjected to intense light from the main amplifier flashlamps. The number density of particles per unit volume is measure after each flash. A measurement of an average of fewer than 1000 particles >0.5{micro}m in diameter produced per square foot of exposed surface per flash for each of the last ten flashes in a series of 60 flashes of light is deemed to be acceptable for polymers. A measurement of an average of fewer than 100 particles >0.5{micro}m in diameter produced per square foot of exposed surface per flash for each of the last ten flashes in a series of 60 flashes of light is deemed to be acceptable for metals

Experimental study of variations in background radiation and the effect on Nuclear Car Wash sensitivity

Error rates in a cargo screening system such as the Nuclear Car Wash [1-7] depend on the standard deviation of the background radiation count rate. Because the Nuclear Car Wash is an active interrogation technique, the radiation signal for fissile material must be detected above a background count rate consisting of cosmic, ambient, and neutron-activated radiations. It was suggested previously [1,6] that the Corresponding negative repercussions for the sensitivity of the system were shown. Therefore, to assure the most accurate estimation of the variation, experiments have been performed to quantify components of the actual variance in the background count rate, including variations in generator power, irradiation time, and container contents. The background variance is determined by these experiments to be a factor of 2 smaller than values assumed in previous analyses, resulting in substantially improved projections of system performance for the Nuclear Car Wash

Nuclear Car Wash sensitivity in varying thicknesses of wood and steel cargo

The influence of incident neutron attenuation on signal strengths in the Nuclear Car Wash has been observed experimentally for both wood and steel-pipe mock cargos. Measured decay curves are presented for {beta}-delayed high-energy {gamma}-rays and thermalized neutrons following neutron-induced fission of HEU through varying irradiation lengths. Error rates are extracted for delayed-{gamma} and delayed-n signals integrated to 30 seconds, assuming Gaussian distributions for the active background. The extrapolation to a field system of 1 mA deuterium current and to a 5 kg sample size is discussed

Description of ALARMA: the alarm algorithm developed for the Nuclear Car Wash

The goal of any alarm algorithm should be that it provide the necessary tools to derive confidence limits on whether the existence of fissile materials is present in cargo containers. It should be able to extract these limits from (usually) noisy and/or weak data while maintaining a false alarm rate (FAR) that is economically suitable for port operations. It should also be able to perform its analysis within a reasonably short amount of time (i.e. {approx} seconds). To achieve this, it is essential that the algorithm be able to identify and subtract any interference signature that might otherwise be confused with a fissile signature. Lastly, the algorithm itself should be user-intuitive and user-friendly so that port operators with little or no experience with detection algorithms may use it with relative ease. In support of the Nuclear Car Wash project at Lawrence Livermore Laboratory, we have developed an alarm algorithm that satisfies the above requirements. The description of the this alarm algorithm, dubbed ALARMA, is the purpose of this technical report. The experimental setup of the nuclear car wash has been well documented [1, 2, 3]. The presence of fissile materials is inferred by examining the {beta}-delayed gamma spectrum induced after a brief neutron irradiation of cargo, particularly in the high-energy region above approximately 2.5 MeV. In this region naturally occurring gamma rays are virtually non-existent. Thermal-neutron induced fission of {sup 235}U and {sup 239}P, on the other hand, leaves a unique {beta}-delayed spectrum [4]. This spectrum comes from decays of fission products having half-lives as large as 30 seconds, many of which have high Q-values. Since high-energy photons penetrate matter more freely, it is natural to look for unique fissile signatures in this energy region after neutron irradiation. The goal of this interrogation procedure is a 95% success rate of detection of as little as 5 kilograms of fissile material while retaining at most .1% false alarm rate. Plywood is used to simulate hydrogenous cargo material and steel (pipes) is used to simulate metallic cargo. The wood consists of 120 x 240 cm sheets and has approximately .65 g/cm{sup 3}. The steel pipes have approximately 10 cm diameters x 6.4 mm wall thickness are .6 g/cm{sup 3}. Fissile sources consist of a ''large'' (380 g) and ''small'' (250 g) sample of HEU (U{sub 3}O{sub 8} 94% enriched). Note that the masses of the HEU sources used in our experimental runs are at least an order of magnitude smaller than 5 kilograms. Runs are done with either wood or steel cargoes stacked at various heights and the HEU sources placed at various depths within the cargo

Intake of macro- and micronutrients in Danish vegans

BACKGROUND: Since information about macro- and micronutrient intake among vegans is limited we aimed to determine and evaluate their dietary and supplementary intake. METHODS: Seventy 18–61 years old Danish vegans completed a four-day weighed food record from which their daily intake of macro- and micronutrients was assessed and subsequently compared to an age-range-matched group of 1 257 omnivorous individuals from the general Danish population. Moreover, the vegan dietary and supplementary intake was compared to the 2012 Nordic Nutrition Recommendations (NNR). RESULTS: Dietary intake differed significantly between vegans and the general Danish population in all measured macro- and micronutrients (p < 0.05), except for energy intake among women and intake of carbohydrates among men. For vegans the intake of macro- and micronutrients (including supplements) did not reach the NNR for protein, vitamin D, iodine and selenium. Among vegan women vitamin A intake also failed to reach the recommendations. With reference to the NNR, the dietary content of added sugar, sodium and fatty acids, including the ratio of PUFA to SFA, was more favorable among vegans. CONCLUSIONS: At the macronutrient level, the diet of Danish vegans is in better accordance with the NNR than the diet of the general Danish population. At the micronutrient level, considering both diet and supplements, the vegan diet falls short in certain nutrients, suggesting a need for greater attention toward ensuring recommended daily intake of specific vitamins and minerals. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12937-015-0103-3) contains supplementary material, which is available to authorized users

Regional differences in portion size consumption behaviour: Insights for the global food industry

Abstract: Given the influence of globalization on consumer food behaviour across the world, the purpose of this paper is to contribute to the theoretical discourse around food portion size as a global consumption-related symbol and its underlying socio-economic drivers for food industry strategy. Overall, 25,000 global food consumers were surveyed across 24 countries to elicit insight on portion size consumption behaviour as well as consumer perception on eating and drinking small portion size within selected socio-economic classes. The data was quantitatively analysed to answer the pertinent research objectives. In 20 out of the 24 global markets surveyed, large food portion size was statistically established as a prevalent consumption-related symbol. The paper found that there are regional differences in portion size food consumption behaviour, and further disparities exist across age, gender and income status in 24 countries covering all regions, including Australia, China, Mexico, South Africa, United Kingdom and United States of America. The outlined food industry implications reveal that adaptation and standardisation strategies are still relevant in global food and nutrition strategy as revealed by the variations in the preference for food portion sizes across various countries of the world