115 research outputs found
JUPITER-II Program: ANL analysis of ZPPR-13A and ZPPR-13B
The ZPPR-13 experiments provide basic physics data for radial heterogeneous LMFBR cores of approximately 700MWe size. Assemblies ZPPR-13A, ZPPR-13B and ZPPR-13A comprised the JUPITER-II cooperative program between the U.S. Department of Energy (US DOE) and PNC of Japan. The measurements were made between August 1982 and April 1984. The core designs and the measurements were planned jointly by the two parties with substantial input from U.S. industrial interests to ensure coverage of the design requirements. This report describes in detail the results of the Argonne National Laboratory (ANL) analyses of phases 13A and 13B/1 and includes preliminary results for the later assemblies of phase 13B.
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Experimental studies of a large heterogeneous LMFBR benchmark core, ZPPR-13A
The ZPPR-13 program provides basic physics information for testing calculations of radially heterogeneous cores of about 700 MWe size. ZPPR-13 is part of the JUPITER cooperative program between Japan and the US. The results are presented of measurements and analysis for the first assembly, ZPPR-13A. These are the first data for heterogeneous cores of this size available in the US and complement results from ZPPR-9, a conventional LMFBR of similar size
Physicochemical and Biological Evaluation of siRNA Polyplexes Based on PEGylated Poly(amido amine)s
PURPOSE: Use of RNA interference as novel therapeutic strategy is hampered by inefficient delivery of its mediator, siRNA, to target cells. Cationic polymers have been thoroughly investigated for this purpose but often display unfavorable characteristics for systemic administration, such as interactions with serum and/or toxicity. METHODS: We report the synthesis of a new PEGylated polymer based on biodegradable poly(amido amine)s with disulfide linkages in the backbone. Various amounts of PEGylated polymers were mixed with their unPEGylated counterparts prior to polyplex formation to alter PEG content in the final complex. RESULTS: PEGylation effectively decreased polyplex surface charge, salt- or serum-induced aggregation and interaction with erythrocytes. Increasing amount of PEG in formulation also reduced its stability against heparin displacement, cellular uptake and subsequent silencing efficiency. Yet, for polyplexes with high PEG content, significant gene silencing efficacy was found, which was combined with almost no toxicity. CONCLUSIONS: PEGylated poly(amido amine)s are promising carriers for systemic siRNA delivery in vivo
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Argonne National Laboratory Reports
An outline is presented for an experimental program to develop and evaluate nondestructive assay techniques applicable to holdup measurement in plutonium-containing fuel fabrication facilities. The current state-of-the-art in holdup measurements is reviewed. Various aspects of the fuel fabrication process and the fabrication facility are considered for their potential impact on holdup measurements. The measurement techniques considered are those using gamma-ray counting, neutron counting, and temperature measurement. The advantages and disadvantages of each technique are discussed. Potential difficulties in applying the techniques to holdup measurement are identified. Experiments are proposed to determine the effects of such problems as variation in sample thickness, in sample distribution, and in background radiation. These experiments are also directed toward identification of techniques most appropriate to various applications. Also proposed are experiments to quantify the uncertainties expected for each measurement
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Autoradiography as a safeguards technique
Autoradiography gives a simultaneous piece count and attribute check for special nuclear material without, however, a quantitative measurement of fissile material. Applications to fuel elements containing plutonium for fast critical assemblies or uranium for LWRs are discussed. 15 figures
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Autoradiographic inventory methods
Described are autoradiographic techniques which can verify the number and SNM content of plutonium- and uranium-containing fuel elements. These techniques are applied to fast critical assembly fuel and to low-enriched uranium in LWR fuel assemblies. Autoradiographic images are formed by the spontaneously emitted X and gamma rays from the fuel elements striking X-ray film in contact with the fuel elements or their containers. Autoradiography allows a large number of items to be examined in a minimum inspection time and with minimum facility impact. Results are presented for fast critical assembly fuel in a variety of storage modes as well as in fast critical assemblies themselves. Results are also presented for low-enriched uranium rods in unirradiated LWR fuel assemblies. In all cases, missing fuel elements or substitution of elements containing inert material or depleted uranium were detected. (6 figs.
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Argonne National Laboratory Reports
A nondestructive autoradiographic technique is described which can provide a verification of the piece count and the plutonium content of plutonium-containing fuel elements. This technique uses the spontaneously emitted gamma rays from plutonium to form images of fuel elements on photographic film. Autoradiography has the advantage of providing an inventory verification without the opening of containers or the handling of fuel elements. Missing fuel elements, substitution of nonradioactive material, and substitution of elements of different size are detectable. Results are presented for fuel elements in various storage configurations and for fuel elements contained in a fast critical assembly
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Experiments and analysis for an axially heterogeneous LMR assembly at ZPPR
Experiments in ZPPR-17 provided physics data for a full-scale (700 MWe) axially heterogeneous LMR. Measurements and analysis are reported for control rod worths, reaction rate distributions, gamma dose distribution, sodium void worths and criticality. Agreement between measurement and calculation are generally satisfactory, but the axial heterogeneity did introduce analytical complications. Some calculational methods gave less good agreement with measurements than in previous homogeneous or radially heterogeneous assemblies. 10 refs., 7 figs., 6 tabs
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Argonne National Laboratory Reports
A nondestructive autoradiographic method is described which can provide a verification that rods in the interior of unirradiated LWR fuel assemblies contain low-enriched uranium. Sufficient absorber must be used to reduce contributions to image density by beta radiation from uranium-238 daughters. When appropriate absorbers are used, the density of the image of a uranium-containing fuel rod is proportional to the uranium-235 enrichment in that rod. Exposure times as short as 1.5 hours can be achieved by using fast film and intensifying screens. Methods are discussed for reducing contributions to the image density of any single rod from radiation produced by all other rods in the assembly. The technique is useful for detecting missing rods, dummy rods, and rods containing depleted uranium. These defects can be detected by visual inspection of the autoradiographs. In its present state of development, the technique is not sensitive enough to reliably detect the difference between the various uranium-235 enrichments encountered in current BWR fuel assemblies. Results are presented for field tests of the technique at BWR and PWR facilities
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In-cell reaction rate distributions and cell-average reaction rates in fast critical assemblies
Measurements are described for determining average values of fission rates in /sup 235/U, /sup 238/U and /sup 239/Pu and capture rates in /sup 238/U for heterogeneous cells used to construct fast critical assemblies. The measurements are based on irradiations of foils of /sup 238/U, /sup 235/U and /sup 239/Pu with counting of fission and capture products using gamma-ray spectroscopy. Both plate and pin cells are considered. Procedures are described for inferring cell-average reaction rate values from a single foil location based on a cell using a quantity called a cell factor. Cell factors are determined from special measurements in which several foils are irradiated within a cell. Comparisons are presented between cell factors determined by measurements and by Monte Carlo calculations which lend credibility to the measurement procedures
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