Phase Stability and Segregation in Alloy 22 Base Metal and Weldments

The current design of the waste disposal containers relies heavily on encasement in a multi-layered container, featuring a corrosion barrier of Alloy 22, a Ni-Cr-Mo-W based alloy with excellent corrosion resistance over a wide range of conditions. The fundamental concern from the perspective of the Yucca Mountain Project, however, is the inherent uncertainty in the (very) long-term stability of the base metal and welds. Should the properties of the selected materials change over the long service life of the waste packages, it is conceivable that the desired performance characteristics (such as corrosion reistance) will become compromised, leading to premature failure of the system. To address this, we will study the phase stability and solute segregation characteristics of Alloy 22 base metal and welds. A better understanding of the underlying microstructural evolution tendencies, and their connections with corrosion behavior will (in turn) produce a higher confidence in the extrapolated behavior of the container materials over time periods that are not feasibly tested in a laboratory. Additionally, the knowledge gained here may potentially lead to cost savings through development of safe and realistic design constraints and model assumptions throughout the entire disposal system

Agro-environmental evaluation of vineyard management using organic farming and integrated plant production systems

Organic farming is often considered to be the most environmentally-friendly crop management system, even if integrated production also aims at decreasing the impact of agriculture on the natural environment. In order to establish references for the agro-environmental evaluation of these two production systems in relation to grape growing, INRA carried out an initial study from 2001 to 2004 at the plot scale. This study focused on two grape varieties (Merlot N and Cabernet Sauvignon) in its Couhins vineyard (Graves cru classé), located on two organically-farmed plots and two plots using integrated production, a system based on the implementation of decision rules aimed at limiting the number of pest control treatments. Production means only differed in terms of pest control management (choice of products and application strategy). Each of the parcels covered approximately 0.30 ha. An agro-environmental evaluation of these two systems was made for 2003, using the INDIGO Vigne method at the plot level. Because of their nature, the choice of parameters for the indicators used determines the interpretation of the results. Nevertheless, it appears that the environmental impact of integrated production is more favourable in this case than that of organic farming, particularly in terms of pest control and energy indicators. One of the reasons for this is the high number of applications of pest control treatments in organic farming and, as a result, higher energy consumption, as well as the use of copper that has a major impact on deep waters, the ground and the air. The two systems can decrease their environmental impact by limiting the number of tractor runs for soil maintenance. Flexibility appears to be greater in the case of integrated production since, contrary to organic farming, it can use herbicides under the row. The calculation of the agro-environmental evaluation on the parcel using integrated protection with chemical weeding under the row leads to a clear improvement of the energy indicator, without significantly decreasing the value of the pest control indicator. Natural sodding of the inter-row, when the vigour of the vineyard allows it, provides an effective solution since the decrease in the number of tractor runs leads to an improvement of erosion and organic matter indicators. This type of evaluation should be carried out at the scale of a group of plots or of an entire wine-farm. Ground maintenance is an important factor in decreasing the impact of grape growing on the environment. In this respect, organic farming offers some promising prospects

Do Courts Change Politics? Heller and the Limits of Policy Feedback Effects

District of Columbia v. Heller was a landmark ruling in which the Supreme Court established that citizens have a constitutional right to possess firearms in their homes for self-protection. The 5-4 decision—along with the Court’s subsequent ruling in McDonald v. Chicago—upended the prevailing wisdom that the Second Amendment protected the right of the states to assemble militias for collective security. In this Article, we examine the effects of these rulings on gun regulation in the United States and, more to the point, on gun politics. We situate our analysis within several related theoretical frameworks, most notably those focused on policy feedback and on the role of courts in producing social change. We argue that the effects of Heller (together with the parallel decision in McDonald) have been rather limited. We examine the rulings’ first-order effects on pre-existing gun control laws, as well as second-order effects on a number of related outcomes. We find that Heller and its progeny have had generally small or non-existent impacts on gun policy, on the organizational capacities and political strategies of pro-gun and pro-regulation groups, and on public attitudes toward gun regulation. Our findings support a constrained view of the Court’s ability to drive social and political change. We conclude, however, by noting that recent developments—particularly hints that some Supreme Court Justices are eager to develop Second Amendment jurisprudence—have the potential to alter these conclusions

Parametrization of Realistic Bethe-Salpeter Amplitude for the Deuteron

The parametrization of the realistic Bethe-Salpeter amplitude for the deuteron is given. Eight components of the amplitude in the Euclidean space are presented as an analytical fit to the numerical solution of the Bethe-Salpeter equation in the ladder approximation. An applicability of the parametrization to the observables of the deuteron is briefly discussed.Comment: LaTeX, 11 pages, 2 Postscript figures; Text of the Fortran program is available from the author by reques

Skyrmions and the Nuclear Force

The derivation of the nucleon-nucleon force from the Skyrme model is reexamined. Starting from previous results for the potential energy of quasistatic solutions, we show that a calculation using the Born-Oppenheimer approximation properly taking into account the mixing of nucleon resonances, leads to substantial central attraction. We obtain a potential that is in qualitative agreement with phenomenological potentials. We also study the non-adiabatic corrections, such as the velocity dependent transition potentials, and discuss their importance.Comment: 24 pages, UPR-0124M

Numerical simulations in the development of the French radioactive waste vitrification processes using induction furnace

International audienceFor many years, the CEA (Commissariat à l’Énergie Atomique et aux Énergies Alternatives) Marcoule France has developed various processes dedicated to radioactive waste confinement, especially vitrification processes for HLLW. For 15 years now, the numerical simulation has become an important tool for research and developement projects held in the CEA-AREVA Joint Vitrification Laboratory (LCV). Induction heating, fluid mechanics and thermal simulations take part of all new R&D projects. The apports of such simulations are, first, the enhancement of the working knowledge of existing process. Those data are very useful to define optimisation choices, for example upgrades made on the hot metallic melter used since the 90s at LaHague facility. Second, the simulations are, of course, also used at the conception stage of new processes as a tool allowing wide ranges parametric tests. This has been extensively used in the design of the cold crucible inductive melter (CCIM) commissioned in 2010 at La Hague plant. Finally, it is a powerful and relatively cheap tool for prospective studies for processes of the future. Whatever the purpose, the potential benefits are gains on the reliability, the output capacity and the life time

Cross section and analyzing power of pol{p}p -> pn pi+ near threshold

The cross section and analyzing power of the pol{p}p -> pn pi+ reaction near threshold are estimated in terms of data obtained from the pol{p}p -> d pi+ and pp -> pp pi0 reactions. A simple final state interaction theory is developed which depends weakly upon the form of the pion-production operator and includes some Coulomb corrections. Within the uncertainties of the model and the input data, the approach reproduces well the measured energy dependence of the total cross section and the proton analyzing power at a fixed pion c.m. angle of 90deg, from threshold to T_p = 330 MeV. The variation of the differential cross section with pion angle is also very encouraging.Comment: 20 pages, Latex including 4 eps figure

Impact of the European Clinical Trials Directive on prospective academic clinical trials associated with BMT

The European Clinical Trials Directive (EU 2001; 2001/20/EC) was introduced to improve the efficiency of commercial and academic clinical trials. Concerns have been raised by interested organizations and institutions regarding the potential for negative impact of the Directive on non-commercial European clinical research. Interested researchers within the European Group for Blood and Marrow Transplantation (EBMT) were surveyed to determine whether researcher experiences confirmed this view. Following a pilot study, an internet-based questionnaire was distributed to individuals in key research positions in the European haemopoietic SCT community. Seventy-one usable questionnaires were returned from participants in different EU member states. The results indicate that the perceived impact of the European Clinical Trials Directive has been negative, at least in the research areas of interest to the EBMT

Final state interaction effects in mu-capture induced two-body decay of 3He

The mu-capture process on 3He leading to a neutron, a deuteron and a mu-neutrino in the final state is studied. Three-nucleon Faddeev wave functions for the initial 3He bound and the final neutron-deuteron scattering states are calculated using the BonnB and Paris nucleon-nucleon potentials. The nuclear weak current operator is restricted to impulse approximation. Large effects on the decay rates of the final state interaction are found. The comparison to recent experimental data shows that the inclusion of final state interactions drastically improves the description of the data.Comment: 14 pages, 6 eps figure

A probable giant planet imaged in the Beta Pictoris disk

Since the discovery of its dusty disk in 1984, Beta Pictoris has become the prototype of young early-type planetary systems, and there are now various indications that a massive Jovian planet is orbiting the star at ~ 10 AU. However, no planets have been detected around this star so far. Our goal was to investigate the close environment of Beta Pic, searching for planetary companion(s). Deep adaptive-optics L'-band images of Beta Pic were recorded using the NaCo instrument at the Very Large Telescope. A faint point-like signal is detected at a projected distance of ~ 8 AU from the star, within the North-East side of the dust disk. Various tests were made to rule out with a good confidence level possible instrumental or atmospheric artifacts. The probability of a foreground or background contaminant is extremely low, based in addition on the analysis of previous deep Hubble Space Telescope images. The object L'=11.2 apparent magnitude would indicate a typical temperature of ~1500 K and a mass of ~ 8 Jovian masses. If confirmed, it could explain the main morphological and dynamical peculiarities of the Beta Pic system. The present detection is unique among A-stars by the proximity of the resolved planet to its parent star. Its closeness and location inside the Beta Pic disk suggest a formation process by core accretion or disk instabilities rather than a binary-like formation process.Comment: 5 pages, 3 figures, 1 table. A&A Letters, in pres