Page 1
Page 2
Page 3
Page 4
Page 5
Page 6
Page 7
Page 8
Page 9
Page 10
Page 11
Page 12
Page 13
Page 14
Page 15
Page 16
Page 17
Page 18
Page 19
Page 20
Page 21
Page 22
Page 23
Page 24
Page 25
Page 26
Page 27
Page 28
Page 29
Page 30
Page 31
Page 32
Page 33
Page 34
Page 35
Page 36
Page 37
Page 38
Page 39
Page 40
Page 41
Page 42
Page 43
Page 44
Page 45
Page 46
Page 47
Page 48
Page 49
Page 50
Page 51
Page 52
Page 53
Page 54
Page 55
Page 56
Page 57
Page 58
Page 59
Page 60
Page 61
Page 62
Page 63
Page 64
Page 65
Page 66
Page 67
Page 68
Page 69
Page 70
Page 71
Page 72
Page 73
Page 74
Page 75
Page 76
Page 77
Page 78
Page 79
Page 80
Page 81
Page 82
Page 83
Page 84
Page 85
Page 86
Page 87
Page 88
Page 89
Page 90
Page 91
Page 92
Page 93
Page 94
Page 95
Page 96
Page 97
Page 98
Page 99
Page 100
Page 101
Page 102
Page 103
Page 104
Page 105
Page 106
Page 107
Page 108
Page 109
Page 110
Page 111
Page 112
Page 113
Page 114
Page 115
Page 116
Page 117
Page 118
Page 119
Page 120
Page 121
Page 122
Page 123
Page 124
Page 125
Page 126
Page 127
Page 128
Page 129
Page 130
Page 131
Page 132
Page 133
Page 134
Page 135
Page 136
Page 137
Page 138
Page 139
Page 140
Page 141
Page 142
Page 143
Page 144
Page 145
Page 146
Page 147
Page 148
Page 149
Page 150
Page 151
Page 152
Nuclear Science User Facilities 112 Development of Advanced Crystallographic Analysis Technique for Localized Fission Product Transport in Irradiated Silicon-Carbide Isabella van Rooyen Idaho National Laboratory isabella.vanrooyeninl.gov The proposed study aims to perform compositional analysis to gain insight into a possible link between crystallographic informa- tion and fission products location in the silicon-carbide SiC layer of tristructural isotropic TRISO fuel.This information will help identify transport mechanisms for these fission products especially silver Ag as they migrate through the SiC layer. Recent work has shown that it is only possible to identify low concentrations of fission products inTRISO-coated particles especiallyAg using transmis- sion electron microscopy TEM with a field emission gun FEG 1.The preliminary results of this study indicate that fission products are primarily associated with some but not all grain boundaries and triple junctions. Knowledge of the grain boundary crys- tallographic parameters will be required to explain the varied fission transport behaviors associated with individual grain boundaries. Currently no efficient way exists for measuring the grain boundary parame- ters while correlating them with fission product transport behavior.What is needed is a way of measuring both the chemistry at the grain boundary and the grain boundary parameters. Since the chemical analysis resolution has only been demonstrated in the FEG TEM a technique of measuring the grain boundary parameters in theTEM is also required. Attempts at measuring the grain boundary parameters using Kikuchi bands inTEM electron diffraction patterns under theAdvanced Gas Reactor AGR-1 program have been unsuc- cessful. However an emerging tech- nique utilizingASTAR software from NanoMEGAS SPRL which examines the intensity of electron diffraction spots in precession electron diffraction PED patterns shows potential for deter- mining the necessary crystallographic parameters in theTEM Project Description This project consists of two phases. In the first researchers will develop the ASTAR technique and evaluate its resolu- tion and reliability when examining SiC from an unirradiatedTRISO fuel particle. The second phase and the main focus of this project will be to characterize the grain and grain boundary parameters in the SiC layer of irradiatedTRISO fuel particles.Table 1 outlines the samples to be analyzed and the expected outcomes. Phase 1 Research on unirriadiated SiC and sample optimization forASTAR Thicker samples increase the possibility of multiple grains being present in the focused ion beam FIB sample. Electron diffraction caused by these multiple grains degradesASTARs ability to identify the correct crystal- lographic orientation.Therefore three TEM lamellae of unirradiated SiC with different thicknesses will be prepared using FIB techniques 50 100 and 150 nm at CAES or the Electron Microscopy Laboratory EML.The quality of theASTAR data will be evaluated for each thickness from the reliability map.The data obtained from these samples will also provide the baseline microstructure and crystal- lographic information texture of the as-fabricated SiC layer which will then be compared to that of SiC from irradi- atedTRISO particles. Phase 2 Research on irriadiated SiC The main objective is to demonstrate that ASTAR can be used to determine the crystallographic information of grains in irradiated SiC determine the grain boundary parameters using the crystallographic orientations of adjacent SiC grains and correlate that information with the transport of fission products. Samples have already This study provides first-of-a-kind nano-crystallographic information on neutron-irradiated TRISO fuels by the application of precession electron diffraction measurements.