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Matthews, Christopher

Publications and source records attributed to Matthews, Christopher.

79 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Constituent Redistribution in U-Zr Metallic Fuel Using the Advanced Fuel Performance Code BISON

Previous work done by Galloway, et. al. on EBR-II ternary (U-Pu-Zr) fuel constituent redistribution yielded accurate simulation data for the limited data sets of Zr redistribution. The data sets included EPMA scans of two different irradiated rods. First, T179, which was irradiated to 1.9 at% burnup, was analyzed. Second, DP16, which was irradiated to 11 at% burnup, was analyzed. One set of parameters that most accurately represented the zirconium profiles for both experiments was determined. Since the binary fuel (U-Zr) has previously been used as the driver fuel for sodium fast reactors (SFR) as well as being the likely driver fuel if a new SFR is constructed, this same process has been initiated on the binary fuel form. From limited binary EPMA scans as well as other fuel characterization techniques, it has been observed that zirconium redistribution also occurs in the binary fuel, albeit at a reduced rate compared to observation in the ternary fuel, as noted by Kim et. al. While the rate of redistribution has been observed to be slower, numerous metallographs of U-Zr fuel show distinct zone formations.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2016

Updated Phase Calculation Method for Metallic Nuclear Fuel in BISON

Zirconium based metallic nuclear fuel undergoes significant redistribution of its constituents, resulting in several different phases present within a single fuel pin. Primarily dominated by the movement of zirconium in U-Pu-Zr and UZr fuels, phase changes result in a three (or more) zoned fuel structure clearly visible during post-irradiation examination (PIE). Each of these regions may posses differing material properties, requiring knowledge of the relative concentration of each phase in order for fuel performance codes to capture the relevant fuel behavior. The model described here was implemented into the fuel performance code BISON, similar to previous work for modeling zirconium redistribution in U-Pu-Zr fuel. However, the modules have since been updated with several key assumptions for easier use in future zirconium redistribution work and other phase-dependent material properties implementation, as discussed in the following sections. A new material model has been implemented in BISON to calculate the fractional phase concentrations as a function of temperature and zirconium concentration. Instead of smoothing the material properties to ensure numerical convergence, the new model smoothes the phase contributions directly, allowing easier implementation of material properties. By comparing the zirconium distribution for different smoothing parameters, it was shown that the smoothing parameters utilized here was adequate for the parameters of interest, while decreasing computational expense. The calculated phase information has been used to determine phase-dependent diffusivities, and is available for other phase-dependent properties. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
NASA NTRS2012

System Engineering Paper

The Iowa State University team, Team LunaCY, is composed of the following sub-teams: the main student organization, the Lunabotics Club; a senior mechanical engineering design course, ME 415; a senior multidisciplinary design course, ENGR 466; and a senior design course from Wartburg College in Waverly, Iowa. Team LunaCY designed and fabricated ART-E III, Astra Robotic Tractor- Excavator the Third, for the team's third appearance in the NASA Lunabotic Mining competition. While designing ART-E III, the team had four main goals for this year's competition:to reduce the total weight of the robot, to increase the amount of regolith simulant mined, to reduce dust, and to make ART-E III autonomous. After many designs and research, a final robot design was chosen that obtained all four goals of Team LunaCY. A few changes Team LunaCY made this year was to go to the electrical, computer, and software engineering club fest at Iowa State University to recruit engineering students to accomplish the task of making ART-E III autonomous. Team LunaCY chose to use LabView to program the robot and various sensors were installed to measure the distance between the robot and the surroundings to allow ART-E III to maneuver autonomously. Team LunaCY also built a testing arena to test prototypes and ART-E III in. To best replicate the competition arena at the Kennedy Space Center, a regolith simulant was made from sand, QuickCrete, and fly ash to cover the floor of the arena. Team LunaCY also installed fans to allow ventilation in the arena and used proper safety attire when working in the arena . With the additional practice in the testing arena and innovative robot design, Team LunaCY expects to make a strong appearance at the 2012 NASA Lunabotic Mining Competition. .

Heise, James↗