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Comparison of US/FRG accident condition fuel failure and release models

Description: Although there are many differences between the High-Temperature Gas Cooled Reactor (HTGR) concepts being developed in the US and the High Temperature Reactor (HTR) concepts in the Federal Republic of Germany (FRG), the coated fuel particles are very similar. Significant benefits are achievable through cooperative research and exchange of information and data on the fuel performance and radionuclide retention in the coated fuel particles. This draft report describes cooperative work on HTGR safety research as agreed to in the "USA/FRG Umbrella Agreement for Cooperation in GCR Development: Safety Research Subprogram Plan," specifically, this work was conducted under Project Work Statement (PWS) S-6 titled "Fission Product Retention in Fuel," 9 refs., 12 figs., 4 tabs.
Date: May 29, 1989
Creator: Bolin, J. & Dunn, T.
Partner: UNT Libraries Government Documents Department

Operating procedure for SiC defect detection: Data support document

Description: The feasibility of the Hg Intrusion QC method for measuring SiC coating defects for the MHTGR was conducted as a potential improvement for the Burn/Leach (B/L) QC method currently used. The purpose for evaluating the Hg Intrusion QC method as an alternative method was to determine if B/L QC method underestimated SiC coating defects. Some evidence in work conducted earlier, indicated that TRISO-coated fuel particles with low SiC coating defects measured by the B/L QC method showed higher releases of metallic fission products. These data indicated that the SiC coating defect fractions were higher than the B/L measured data indicated. Sample sizes used in the current study were too small to conclusively demonstrate that the B/L QC method under estimate SiC coating defects. However, observations made during this study indicated a need for an additional QC method to the B/L QC method to measure SiC coating defects for the higher quality MHTGR fuels. The B/L QC method is the best method for measuring SiC coating defects with missing SiC layers or broken SiC coatings (gross SiC defects). However, SiC coating defects with microcracks and other SiC defects not detected by the B/L method may contribute to the release of metallic fission products in-service. For these type of SiC coating defects, the Hg Intrusion QC method investigated in this study is feasible, but particle sample size should be increased to a much larger sample size (100,000 particles per test) for the MHTGR. 7 refs., 5 figs., 9 tabs.
Date: September 29, 1989
Creator: Adams, C. C. & Partain, K. E.
Partner: UNT Libraries Government Documents Department

Development of improved TRISO-P fuel particle P-PyC coating

Description: Low defect fuels are required for the MHTGR to meet tighter fuel performance for this reactor design (Ref. 1). Exposed heavy metal (HM) contamination levels must be reduced to {le} 1E-5 fraction. Particle coating breakage during the fuel compact fabrication process has been shown to be a major source of HM contamination in the final fuel compacts. Excessive forces are experienced by the coated fuel particles during matrix injection, which leads to coating failure. Adding a sacrificial, low Young`s modulus, overcoating of low density PyC in a fluidized particle bed, was shown to greatly increase the crush strength of TRISO coated fuel particles in 1986 studies (Ref. 2). The new TRISO coated fuel particle design was designated the TRISO-P coated fuel particle type. In 1987, the TRISO-P particle type was used to produce low defect fuel compacts for irradiation in the HRB-21 Capsule (Ref. 3). However, the exposed HM contamination levels for that fuel barely met the product specification limit of {le} 1.0E-5. The small margin of safety between product quality and the specification limit dictated that additional process development of the TRISO-P particle design must be conducted. This document discusses the program scope, requirements, documentation and schedule.
Date: April 29, 1988
Creator: Adams, C.C.
Partner: UNT Libraries Government Documents Department

MHTGR core temperature measurement trade study

Description: The objective of this task was to assess the need for core non-nuclear instrumentation. The focus of this study was the evaluation of core investment risk events. Three categories of events were considered: (1) unanticipated primary loop flow leakages and core bypass flows, (2) core coolant channel flow blockages and (3) off-design core power distributions. The measurements that were considered include column average coolant exit temperatures, core average coolant exit temperature, core pressure drop and core flow rate. The findings are summarized. 3 refs., 7 figs.
Date: September 29, 1989
Creator: Kapernick, R. & Howard, W.
Partner: UNT Libraries Government Documents Department

Production test IP-376-D: Irradiation of MGCR-HDR-3 test element

Description: The objective of this test detailed in this report is to irradiate a test fuel assembly for the MGCR (Maritime Gas Cooled Reactor). The irradiation of this assembly will be carried out in the DR-1 Loop under controlled conditions to determine the feasibility of the heterogeneous 19-rod bundle fuel element concept. Diffusion of fission products through metal cladding. Fission gas retention of fuel bodies. Dimensional stability of fuel bodies, and satisfactory performance of the creep-shrink process for maintaining pellet position in the fuel pin.
Date: November 29, 1960
Creator: Bennett, E. C.
Partner: UNT Libraries Government Documents Department