PIE on Safety-tested AGR-1 Compacts 5-3-3, 5-1-3, and 3-2-3

PIE on Safety-Tested AGR-1 Compact 5-1-1

“…SEM analysis of randomly-selected particles was conducted on Particle 511-RS09 (M/C < 0.61), Particle 511-RS04 (M/C =1.01), and Particle 511-RS37 (M/C = 1.48); these particles all had average radioisotopic inventories, but exhibited a variation in 110m Ag retention behavior. The overview images in Figure 23 show fission product features segregated in the IPyC layer and piled up at the IPyC/SiC interface, this is consistent with previous observations from SEM analysis of other safety-tested particles [Hunn et al 2014-1;Hunn et al 2014-3]. Figure 24 shows parallel image sets of the SiC layer for these three particles.…”

“…The SiC degradation in Low-Cs/Ce Particle 1 presents a unique case, as the presence of fission products in the OPyC layer surrounding a region of SiC degradation (Figure 10 and Figure 11f) have not been previously observed. The primary features of the SiC degradation remained consistent with previouslyobserved degraded SiC; namely, high-Z fission product features surround the SiC degradation and appear to advance in front of C-rich phases in the SiC layer, where silicon has presumably been removed by formation and out-diffusion of silicide [Hunn et al 2014-1;Hunn et al 2014-2]. Figure 14 shows a set of single-element EDS maps of the higher-concentration elements found in the degraded area.…”

“…This type of krypton release has been observed in all the AGR-1 CCCTF safety tests at 1800°C (all of which had particles with failed SiC) and in the 1700°C safety test of AGR-1 Compact 3-3-1 [Hunn et al 2013-2, page 7], which also exhibited cesium release from particles with failed SiC. Table 2 lists the total detected fission product releases at the end of the Compact 5-1-1 safety test, with a comparison to the other two safety-tested Variant 1 compacts irradiated in Capsule 5 [Hunn et al 2014-1].…”

“…After completion of the safety test, the compact was examined with a standard set of analyses that included the following: (1) detection of exposed fission products by Deconsolidation-Leach-Burn-Leach (DLBL), (2) measurement of the gamma-emitting isotopic inventory within individual particles with the ORNL Irradiated Microsphere Gamma Analyzer (IMGA), and (3) microstructural examination by highresolution x-ray tomography and materialography. The equipment and methods used for the safety testing and post-safety testing PIE were the same as those summarized in a recent report on similar tests performed on other AGR-1 compacts [Hunn et al 2014-1] and have been described in detail in [Baldwin et al 2012] and [Hunn et al 2013-1]. In addition to standard imaging with a scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) for elemental analysis (as described in [Hunn et al 2013-1]), a new Oxford X-Max 50 Silicon Drift Detector EDS system using AZtec acquisition software was used for elemental mapping.…”

Destructive PIE and Safety Testing of Six AGR-2 UO₂ Capsule 3 Compacts

“…Values are reported as compact fractions and particle-equivalents (in parentheses). Observations of gradual release of small amounts of 85 Kr from particles with failed SiC, without subsequent TRISO failure, were observed during the 1,800°C safety testing of AGR-1 Compacts 5-1-3 and 3-2-3 (Hunn et al 2014b). In those tests, the cumulative 85 Kr release was 0.20 particle equivalents from six or seven Compact 5-1-3 particles with failed SiC and 0.25 particle equivalents from eleven Compact 3-2-3 particles with failed SiC.…”