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159. Remote coating in HTGR fuel particles
692
ABSTRACTS
154. Influence of hardener and grain size of filler on the irradiation behaviour or resin bound matrix based on natural graphite W. W. Delle, G. Haag, H. Luhleich, H. Nickel, R. E. Schulze (Kernf~schungsunluge Jiilich GmbH, Jiilich, West Germany) and F. J. Herrmann (Hochtemperatur-Brennelment-Gesellschaft m.bH, Hanuu, West Germany). By addition of hardener to phenolic resin binder, the mechanical properties of fuel matrices are improved. On the other hand, the irradiation-induced shrinkage as well as the anisotropy of the dimensional changes of these materials are increased, which can be compensated by the use of natural graphite with smaller grain size. 155. Resin fuel particles for high-temperature gas-cooled reactors* M. D. Silverman and C. B. Pollock (Metals and Ceramics Division, Oak Ridge National Laboratoy, Oak Ridge, Tennessee). Fuel kernels for HTGR’s have been prepared from both strong- and weak-acid cation exchangers. Carbonization and heat-treatment studies conducted on these uranium-loaded resins have yielded kernels whose composition can be widely varied and correlated with theoretical predictions. 156. Structural changes and microporosity in pyrocarbon and graphite K. Koizlik, P. Krautwasser and H. Nickel (petite fer ~e~~~~~~, K~foyschu~~a~~ge Josh GmbH, W. Germuny). The change of microporosity in matrix material, graphite and pyrocarbon has been studied by X-ray small-angle scattering. During neutron irradiation, microporosity increases in graphite, in matrix material, however, an additional graphitization process reduces the concentration of small pores. During heattreatment, the anisotropy of crystallographic orientation increases. It could be shown that the process mainly responsible for the anisotropy increases is the stress-directed diffusion of thermally activated point defects. 157. Irradiation stability of carbon coatings on HTGR fuel particles* J. H. Coobs, C. B. Pollock, W. P. Eatherly and J. M. Robbins (Mean and Ceramics ~iv~~~, Oak Ridge h$&onal Laboratory, Oak Ridge, Tennessee). Two-layer carbon coatings were designed and a series of 4OOand 500~pm-dia ThO, particles were prepared such that some would fail during irradiation in HFIR to fast fluences ranging from 2 to 18 X 102’ neutrons/cm 2. Correlation of results with calculated stresses, using reasonable creep coefficients, indicate that failures occur when creep stress exceeds 25,000 psi. *Research sponsored by the U.S. Atomic Energy Commission under contract with the Union Carbide Corporation. 158. Structural changes in pyrocarbon coatings of spherical particles by heattreatment and neutron irradiation P. Koss (keweichische Studiengesellschaft fur Atomkernenargk, A-1082 W&n, Austria), P. Koizlik, H. Nickel and E. Balthesen (Kernfmschungsanlage Jiilich, D-517 Jtiich, W. Germany). The microstructure of pyrocarbon coatings of fuel particles changes during heat-treatment or neutron irradiation. The effect of heattreatment in the temperature range 1800-2400°C and of irradiation in the reactor with a fast fluence up to 16 X 102l cmT2 (E > 0.1 MeV) and fuel burn up of up to 17 per cent fima on the anisotropy of crystalline orientation of the pyrocarbon coatings was investigated. An increase of anisotropy is observed which is proportional to the temperature, the fluence, and the burn up, and which depends on the material properties before treatment. 159. Remote coating in HTGR fuel particles W. J. Lackey, W. H. Pechin and J. D. Sease (Oak Ridge National Laboratory, Oak Ridge, Tennessee). Equipment and processes are being developed to allow remote coating of 350-pm-dia (Th0.slU0.19)02 recycle fuel particles in the TURF pilot plant at the rate of 10 kg of heavy metal per day. Carbon coatings and perhaps Sic coatings will be required. Particles having the desired coatings have been produced in l- to 3-kg batches in a fluidized bed 5-in.-dia prototype furnace. 169. Some properties of pyrocwbons deposited from propene and the influence of neutron irradiation on the apparent crystallite size H. A. Schulze (K~f~s~un~an~ge J&h GmbH, 5170 Jiitich, W. Germany). Carbons deposited from propene in a fluidized bed in a wide range of temperature were examined. High temperature deposits
ABSTRACTS
154. Influence of hardener and grain size of filler on the irradiation behaviour or resin bound matrix based on natural graphite W. W. Delle, G. Haag, H. Luhleich, H. Nickel, R. E. Schulze (Kernf~schungsunluge Jiilich GmbH, Jiilich, West Germany) and F. J. Herrmann (Hochtemperatur-Brennelment-Gesellschaft m.bH, Hanuu, West Germany). By addition of hardener to phenolic resin binder, the mechanical properties of fuel matrices are improved. On the other hand, the irradiation-induced shrinkage as well as the anisotropy of the dimensional changes of these materials are increased, which can be compensated by the use of natural graphite with smaller grain size. 155. Resin fuel particles for high-temperature gas-cooled reactors* M. D. Silverman and C. B. Pollock (Metals and Ceramics Division, Oak Ridge National Laboratoy, Oak Ridge, Tennessee). Fuel kernels for HTGR’s have been prepared from both strong- and weak-acid cation exchangers. Carbonization and heat-treatment studies conducted on these uranium-loaded resins have yielded kernels whose composition can be widely varied and correlated with theoretical predictions. 156. Structural changes and microporosity in pyrocarbon and graphite K. Koizlik, P. Krautwasser and H. Nickel (petite fer ~e~~~~~~, K~foyschu~~a~~ge Josh GmbH, W. Germuny). The change of microporosity in matrix material, graphite and pyrocarbon has been studied by X-ray small-angle scattering. During neutron irradiation, microporosity increases in graphite, in matrix material, however, an additional graphitization process reduces the concentration of small pores. During heattreatment, the anisotropy of crystallographic orientation increases. It could be shown that the process mainly responsible for the anisotropy increases is the stress-directed diffusion of thermally activated point defects. 157. Irradiation stability of carbon coatings on HTGR fuel particles* J. H. Coobs, C. B. Pollock, W. P. Eatherly and J. M. Robbins (Mean and Ceramics ~iv~~~, Oak Ridge h$&onal Laboratory, Oak Ridge, Tennessee). Two-layer carbon coatings were designed and a series of 4OOand 500~pm-dia ThO, particles were prepared such that some would fail during irradiation in HFIR to fast fluences ranging from 2 to 18 X 102’ neutrons/cm 2. Correlation of results with calculated stresses, using reasonable creep coefficients, indicate that failures occur when creep stress exceeds 25,000 psi. *Research sponsored by the U.S. Atomic Energy Commission under contract with the Union Carbide Corporation. 158. Structural changes in pyrocarbon coatings of spherical particles by heattreatment and neutron irradiation P. Koss (keweichische Studiengesellschaft fur Atomkernenargk, A-1082 W&n, Austria), P. Koizlik, H. Nickel and E. Balthesen (Kernfmschungsanlage Jiilich, D-517 Jtiich, W. Germany). The microstructure of pyrocarbon coatings of fuel particles changes during heat-treatment or neutron irradiation. The effect of heattreatment in the temperature range 1800-2400°C and of irradiation in the reactor with a fast fluence up to 16 X 102l cmT2 (E > 0.1 MeV) and fuel burn up of up to 17 per cent fima on the anisotropy of crystalline orientation of the pyrocarbon coatings was investigated. An increase of anisotropy is observed which is proportional to the temperature, the fluence, and the burn up, and which depends on the material properties before treatment. 159. Remote coating in HTGR fuel particles W. J. Lackey, W. H. Pechin and J. D. Sease (Oak Ridge National Laboratory, Oak Ridge, Tennessee). Equipment and processes are being developed to allow remote coating of 350-pm-dia (Th0.slU0.19)02 recycle fuel particles in the TURF pilot plant at the rate of 10 kg of heavy metal per day. Carbon coatings and perhaps Sic coatings will be required. Particles having the desired coatings have been produced in l- to 3-kg batches in a fluidized bed 5-in.-dia prototype furnace. 169. Some properties of pyrocwbons deposited from propene and the influence of neutron irradiation on the apparent crystallite size H. A. Schulze (K~f~s~un~an~ge J&h GmbH, 5170 Jiitich, W. Germany). Carbons deposited from propene in a fluidized bed in a wide range of temperature were examined. High temperature deposits