Robert Noel Morris

Neutral beam injection benchmark studies for stellarators/heliotrons

Neutral beam injection in stellarators/heliotrons is studied with Monte Carlo codes that treat the initial beam deposition and the fast-ion thermalization process. The birth deposition model carefully treats the geometry of the vacuum vessel and includes beam divergence, focusing, and aperture losses. The thermalization process is determined by integrating the guiding centre equations of the fast ions and simulating collisions with the plasma by Monte Carlo collision operators. This process may include charge exchange and neutral reabsorption. For the purposes of this benchmark, we review the different formulations of the guiding centre equations and the Monte Carlo collision operators. We studied perpendicular injection into Heliotron-E, which is located at the Plasma Physics Laboratory at Kyoto University. The magnetic fields of Heliotron-E are computed using the Biot-Savart law with realistic filament models. The sensitivity of the computed heating efficiency to the modelling of the particle loss boundary and to the numerical procedures is examined. The results of three different codes were compared. When the codes solve the same problem, the answers agree quite well. However, changing some of the modelling assumptions (such as the loss boundary location) can create significant differences in the results.

Experimental techniques for liquid metal cooled fast breeder reactor fuel assembly thermal/hydraulic tests

Abstract Sensors and methods of experimental measurement being employed in fast breeder reactor fuel assembly tests are reviewed. Such tests are being carried out in sodium, water and air environments. In sodium tests direct measurement of bundle performance parameters such as temperature, flow, pressure, boiling inception, and void fraction are being performed. Development of improved instrumentation is needed for reliable fast-response, high-temperature pressure detection and small, more readily interpretable, void detectors. Water and air environment tests are being undertaken to measure parameters used in models which predict design behavior in sodium. Parameters being measured are subchannel average velocity, local axial and transverse velocities, wall shear stress, salt and other tracer concentrations, and turbulence parameters. Adequate techniques exist for measurement of each of these parameters.

New developments in image-based characterization of coated particle nuclear fuel

We describe in this paper new developments in the characterization of coated particle nuclear fuel using optical microscopy and digital imaging. As in our previous work, we acquire optical imagery of the fuel pellets in two distinct manners that we refer to as shadow imaging and cross-sectional imaging. In shadow imaging, particles are collected in a single layer on an optically transparent dish and imaged using collimated back-lighting to measure outer surface characteristics only. In cross-sectional imaging, particles are mounted in acrylic epoxy and polished to near-center to reveal the inner coating layers for measurement. For shadow imaging, we describe a curvaturebased metric that is computed from the particle boundary points in the FFT domain using a low-frequency parametric representation. We also describe how missing boundary points are approximated using band-limited interpolation so that the FFT can be applied. For cross-section imaging, we describe a new Bayesian-motivated segmentation scheme as well as a new technique to correct layer measurements for the fact that we cannot observe the true mid-plane of the approximately spherical particles.

Safety testing of AGR-2 UO2 compacts 3-3-2 and 3-4-2

Post-irradiation examination (PIE) is in progress on tristructural-isotropic (TRISO) coated-particle fuel compacts from the Advanced Gas Reactor (AGR) Fuel Development and Qualification Program second irradiation experiment (AGR-2) [Collin 2014]. The AGR-2 PIE will build upon new information and understanding acquired throughout the recently-concluded six-year AGR-1 PIE campaign [Demkowicz et al. 2015] and establish a database for the different AGR-2 fuel designs.

PIE on safety-tested AGR-1 compact 4-2-2

Post-irradiation examination (PIE) is being performed in support of tristructural isotropic (TRISO) coated particle fuel development and qualification for High-Temperature Gas-cooled Reactors (HTGRs). AGR-1 was the first in a series of TRISO fuel irradiation experiments initiated in 2006 under the Advanced Gas Reactor (AGR) Fuel Development and Qualification Program; this work continues to be funded by the Department of Energys Office of Nuclear Energy as part of the Advanced Reactor Technologies (ART) initiative. AGR-1 fuel compacts were fabricated at Oak Ridge National Laboratory (ORNL) in 2006 and irradiated for three years in the Idaho National Laboratory (INL) Advanced Test Reactor (ATR) to demonstrate and evaluate fuel performance under HTGR irradiation conditions. PIE is being performed at INL and ORNL to study how the fuel behaved during irradiation, and to examine fuel performance during exposure to elevated temperatures at or above temperatures that could occur during a depressurized conduction cooldown event. This report summarizes safety testing of irradiated AGR-1 Compact 5-1-1 in the ORNL Core Conduction Cooldown Test Facility (CCCTF) and post-safety testing PIE.

Multi-tier Analysis of SiC Breaches in Safety-Tested AGR-1 TRISO Fuel Particles

Tristructural isotropic (TRISO) coated particle fuel development is being supported by the US Department of Energy, Office of Nuclear Energy. The development plan includes a series of irradiations to qualify TRISO fuel. The first irradiation, AGR-1, included fuel fabricated at Oak Ridge National Laboratory (ORNL) and irradiated in the Advanced Test Reactor at the Idaho National Laboratory (INL). The TRISO fuel design consisted of a uranium carbide/uranium oxide kernel surrounded by concentric coating layers of carbonaceous buffer, inner pyrolitic carbon (IPyC), silicon carbide (SiC), and outer pyrolitic carbon (OPyC). Particles were then over-coated with carbonaceous matrix material and pressed into a cylindrical compact, with each compact containing greater than 4100 TRISO particles. A total of 72 compacts were included in AGR-1 and the irradiation was completed in November 2009 after ~620 effective full power days [1].