In its current design, the high-level nuclear waste containers include an external layer of Alloy 22 (NO6022). This material was selected to provide long-term corrosion resistance since if water enters in contact with the containers, they may undergo corrosion. The model for the degradation of the containers includes three modes of corrosion, namely general corrosion, localized corrosion and environmentally assisted cracking (EAC). The objective of the current research was to quantify the susceptibility of Alloy 22 to EAC in several environmental conditions with varying solution composition, temperature and electrochemical potential. The susceptibility to EAC was evaluated using constant deformation (deflection) U-bend specimens in both the wrought and welded conditions. Results show that after more than five years exposure in the vapor and liquid phases of alkaline (PH {approx} 10) and acidic (pH {approx} 3) multi-ionic environments at 60 C and 90 C, Alloy 22 was free from EAC.

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We present new results from studies in progress on physics at a two-photon collider. We report on the sensitivity to top squark parameters of MSSM Higgs boson production in two-photon collisions; Higgs boson decay to two photons; radion production in models of warped extra dimensions; chargino pair production; sensitivity to the trilinear Higgs boson coupling; charged Higgs boson pair production; and we discuss the backgrounds produced by resolved photon-photon interactions.

The properties of the strongly interacting matter produced at RHIC are investigated within a chemical and thermal equilibrium chiral SU(3) {sigma}-{omega} approach. The focus is on the freeze-out conditions, the effective masses for the produced hadrons and the expansion of the system. For the freeze-out conditions the commonly adopted noninteracting gas calculations yield temperatures and chemical potentials close to or above the critical temperature for the chiral phase transition, but without taking into account any interactions. Contrary, the chiral SU(3) model predicts temperature and density dependent effective hadron masses and effective chemical potentials in the medium and a transition to a chirally restored phase at high temperatures or chemical potentials. Three different parametrizations of the model, which show different types of phase transition behavior, are investigated. They show that if a chiral phase transition occurred in those collisions, freezing of the relative hadron abundances in the symmetric phase is excluded by the data. Therefore, either very rapid chemical equilibration must occur in the broken phase, or the measured hadron ratios are the outcome of the dynamical symmetry breaking. Furthermore, the extracted chemical freeze-out parameters differ considerably from those obtained in simple noninteracting gas calculations. In particular, the three models yield …

Refractive x-ray lenses have been fabricated using deep x-ray lithography. Lenses were produced directly in 1- to 6-mm-thick sheets of polymethylmethacrylate (PMMA) with as many as 100 cylindrical lenses along the optical axis. The fabrication process consists of exposing the PMMA sheets to high-energy synchrotron radiation through a mask of 50-micron-thick gold on silicon and subsequent development in ketone. The lenses are suitable for use in synchrotron radiation from a bending magnet at the Advanced Photon Source in the energy range of 8-16 keV. Results of measurements of focus quality, flux density gain, and scatter are presented and discussed with regard to the quality of lens material and fabrication method. Means for improving the performance of the lenses is discussed.

Anthropogenic emissions of fine black carbon (BC) particles, the principal light-absorbing atmospheric aerosol, have varied during the past century in response to changes of fossil-fuel utilization, technology developments, and emission controls. We estimate historical trends of fossil-fuel BC emissions in six regions that represent about two-thirds of present day emissions and extrapolate these to global emissions from 1875 onward. Qualitative features in these trends show rapid increase in the latter part of the 1800s, the leveling off in the first half of the 1900s, and the re-acceleration in the past 50 years as China and India developed. We find that historical changes of fuel utilization have caused large temporal change in aerosol absorption, and thus substantial change of aerosol single scatter albedo in some regions, which suggests that BC may have contributed to global temperature changes in the past century. This implies that the BC history needs to be represented realistically in climate change assessments.

The Department of Energy mandated the termination of the Integral Fast Reactor (IFR) Program, effective October 1, 1994. To comply with this decision, Argonne National Laboratory-West (ANL-W) prepared a plan providing detailed requirements to maintain the Experimental Breeder Reactor-II (EBR-II) in a radiologically and industrially safe condition, including removal of all irradiated fuel assemblies from the reactor plant, and removal and stabilization of the primary and secondary sodium, a liquid metal used to transfer heat within the reactor plant. The EBR-II is a pool-type reactor. The primary system contained approximately 325 m{sup 3} (86,000 gallons) of sodium and the secondary system contained 50 m{sub 3} (13,000 gallons). In order to properly dispose of the sodium in compliance with the Resource Conservation and Recovery Act (RCRA), a facility was built to react the sodium to a solid sodium hydroxide monolith for burial as a low level waste in a land disposal facility. Deactivation of a liquid metal fast breeder reactor (LMFBR) presents unique concerns. Residual amounts of sodium remaining in circuits and components must be passivated, inerted, or removed to preclude future concerns with sodium-air reactions that could generate potentially explosive mixtures of hydrogen and leave corrosive compounds. The passivation process …

An experimental primary {gamma}-ray spectrum vs. excitation-energy bin (P(E{sub x}, E{sub {gamma}}) matrix) in a light-ion reaction is obtained for {sup 56,57}Fe isotopes using a subtraction method. By factorizing the P(E{sub x}, E{sub {gamma}}) matrix according to the Axel-Brink hypothesis the nuclear level density and the radiative strength function (RSF) in {sup 56,57}Fe are extracted simultaneously. A step structure is observed in the level density for both isotopes, and is interpreted as the breaking of Cooper pairs. The RSFs for {sup 56,57}Fe reveal an anomalous enhancement at low {gamma}-ray energies.

In this paper we study one-dimensional three-phase flow through porous media of immiscible, incompressible fluids. The model uses the common multiphase flow extension of Darcy's equation, and does not include gravity and capillarity effects. Under these conditions, the mathematical problem reduces to a 2 x 2 system of conservation laws whose essential features are: (1) the system is strictly hyperbolic; (2) both characteristic fields are nongenuinely nonlinear, with single, connected inflection loci. These properties, which are natural extensions of the two-phase flow model, ensure that the solution is physically sensible. We present the complete analytical solution to the Riemann problem (constant initial and injected states) in detail, and describe the characteristic waves that may arise, concluding that only nine combinations of rarefactions, shocks and rarefaction-shocks are possible. We demonstrate that assuming the saturation paths of the solution are straightlines may result in inaccurate predictions for some realistic systems. Efficient algorithms for computing the exact solution are also given, making the analytical developments presented here readily applicable to interpretation of lab displacement experiments, and implementation of streamline simulators.

Design, fabrication, testing, and performance of an x-ray lens assembly are described. The assembly consists of a number of precisely stacked and aligned parts, each of which is a section of an extruded aluminum piece having 16 parabolic cavities. The wall thickness between adjacent cavities is 0.2 mm. By stacking a number of long, extruded parts and cutting the assembly diagonally, a variable-focus lens system is devised. Moving the lens horizontally allows the incident beam to pass through fewer or more cavities focusing the emerging beam at any desired distance from the lens. The variable focus aluminum lens has been used at the Advanced Photon Source to collimate a monochromatic, 8 keV undulator beam. Results indicate collimation consistent with theoretical expectations.

At the Advanced Photon Source (APS) concern for radiation-induced demagnetization of the insertion devices (IDs) in the storage ring and in the free-electron laser has initiated systematic radiation effects studies towards the development of efficient techniques for ID protection. The studies include radiation dose monitoring, parametric study of the radiation-induced demagnetization, as well as, potentially, a dedicated radiation effects testbed at the APS providing GeV electron beams. Such studies could also be directly applicable to future generation facilities, such as the Linac Coherent Light Source (LCLS). Results and discussion of the radiation damage studies at APS are presented.

The Channel Control ASIC (CCA) is used along with a custom Charge Integrator and Encoder (QIE) ASIC to digitize signals from the hybrid photo diodes (HPDs) and photomultiplier tubes (PMTs) in the CMS hadron calorimeter. The CCA sits between the QIE and the data acquisition system. All digital signals to and from the QIE pass through the CCA chip. One CCA chip interfaces with two QIE channels. The CCA provides individually delayed clocks to each of the QIE chips in addition to various control signals. The QIE sends digitized PMT or HPD signals and time slice information to the CCA, which sends the data to the data acquisition system through an optical link.