M2-branes on M-folds

We argue that the moduli space for the Bagger-Lambert A_4 theory at level k is (R^8 \times R^8)/D_{2k}, where D_{2k} is the dihedral group of order 4k. We conjecture that the theory describes two M2-branes on a Z_{2k} ``M-fold'', in which a geometrical action of Z_{2k} is combined with an action on the branes. For k=1, this arises as the strong coupling limit of two D2-branes on an O2^- orientifold, whose worldvolume theory is the maximally supersymmetric SO(4) gauge theory. Finally, in an appropriate large-k limit we show that one recovers compactified M-theory and the M2-branes reduce to D2-branes.Comment: 16 pages, LaTeX, v2: typos corrected, included appendices on Chern-Simons level quantization and monopole charge quantizatio

Evaluation of Effect of Fuel Assembly Loading Patterns on Thermal and Shielding Performance of a Spent Fuel Storage/Transportation Cask

The licensing of spent fuel storage casks is generally based on conservative analyses that assume a storage system being uniformly loaded with design basis fuel. The design basis fuel typically assumes a maximum assembly enrichment, maximum burn up, and minimum cooling time. These conditions set the maximum decay heat loads and radioactive source terms for the design. Recognizing that reactor spent fuel pools hold spent fuel with an array of initial enrichments, burners, and cooling times, this study was performed to evaluate the effect of load pattern on peak cladding temperature and cask surface dose rate. Based on the analysis, the authors concluded that load patterns could be used to reduce peak cladding temperatures in a cask without adversely impacting the surface dose rates

Inhibiting the gastric burst release of drugs from enteric microparticles: the influence of drug molecular mass and solubility.

Undesired drug release in acid medium from enteric microparticles has been widely reported. In this paper, we investigate the relative contribution of microparticle and drug properties, specifically microsphere size and drug's molecular weight and acid solubility, on the extent of such undesired release. A series of nine drugs with different physicochemical properties were successfully encapsulated into Eudragit S and Eudragit L microparticles using a novel emulsion solvent evaporation process. The process yielded spherical microparticles with a narrow size distribution (27-60 and 36-56 µm for Eudragit L and Eudragit S microparticles, respectively). Upon incubation in acid medium (pH 1.2) for 2 h, the release of dipyridamole, cinnarizine, amprenavir, bendroflumethiazide, budesonide and prednisolone from both Eudragit microparticles was less than 10% of drug load and conformed with the USP specifications for enteric dosage forms. In contrast, more than 10% of the entrapped paracetamol, salicylic acid and ketoprofen were released. Multiple regression revealed that the drug's molecular weight was the most important factor that determined its extent of release in the acid medium, while its acid solubility and microsphere's size had minor influences

Characterization of spent fuel approved testing material--ATM-104

The characterization data obtained to date are described for Approved Testing Material 104 (ATM-104), which is spent fuel from Assembly DO47 of the Calvert Cliffs Nuclear Power Plant (Unit 1), a pressurized-water reactor. This report is one in a series being prepared by the Materials Characterization Center at Pacific Northwest Laboratory (PNL) on spent fuel ATMs. The ATMs are receiving extensive examinations to provide a source of well-characterized spent fuel for testing in the US Department of Energy Office of Civilian Radioactive Waste Management (OCRWM) Program. ATM-104 consists of 128 full-length irradiated fuel rods with rod-average burnups of about 42 MWd/kgM and expected fission gas release of about 1%. A variety of analyses were performed to investigate cladding characteristics, radionuclide inventory, and redistribution of fission products. Characterization data include (1) fabricated fuel design, irradiation history, and subsequent storage and handling history; (2) isotopic gamma scans; (3) fission gas analyses; (4) ceramography of the fuel and metallography of the cladding; (5) special fuel studies involving analytical transmission electron microscopy (AEM) and electron probe microanalyses (EPMA); (6) calculated nuclide inventories and radioactivities in the fuel and cladding; and (7) radiochemical analyses of the fuel and cladding

Preliminary neutronics calculations for the super SARA test program. [PWR; BWR]

The Super SARA Test Program (SSTP) is a major European Economic Community effort to study light-water reactor safety during large- and small-break loss-of-coolant accident (LOCA) events in the ESSOR reactor. The SSTP will simulate small-break LOCA's by producing slow temperature ramps to high fuel rod temperatures (approx. 2000/sup 0/C). These experiments will provide data to describe high-temperature, severe-fuel damage mechanisms. The first section describes the reactor and test assembly with respect to neutronics analyses. The calculational methods are discussed in the second section. Results of the analyses are presented in the third section. Finally, the fourth section contains a brief discussion of calculations which should be done to complete the neutronics analyses if additional funding becomes available

Mass flows for LMFBRs fueled with various types of plutonium and fertile material

Results are presented of neutronics analyses performed to determine fueling requirements and mass flows for a typical 1200 megawatt electric (MWe) liquid metal fast breeder reactor (LMFBR). In performing the analyses, three plutonium compositions were considered to fuel the reactor. The composition depended on the amount of irradiation either a UO/sub 2/ or PuO/sub 2/-ThO/sub 2/ fuel had received in a light water reactor (LWR). Uranium and thorium fertile materials were considered. Calculations were performed to determine the cross sections, reactivity, and burnup for each fuel-fertile material configuration. Based on these calculations, the mass flows, plutonium enrichment requirements, and breeding ratios for each configuration were determined