[en] Fission products were injected into thorium disks by the fission recoil doping method at concentrations approximating infinite dilution. Tantalum-wrapped samples were isothermally annealed in an evacuated quartz-kimax tube at 872 to 1177⁰C. Release of ¹³³Xe was monitored during the anneal using a shielded gamma ray spectrometer. For nonvolatile fission products, the samples were sectioned after the anneal for concentration profile analysis using the electropolishing method. Diffusion of Te and Xe is consistent with the accepted theory of vacancy diffusion of substitutional solute impurities in fcc metals. Diffusion of Ba and Ce is close to that of self-diffusion in thorium but is inconsistent with the Lazarus--LeClaire theory. The mechanism is substitutional-interstitial with the substitutional phase dominant. A strong correlation was observed between the activation energy and valence for impurity diffusion in thorium. The fast diffusion observed for ⁹⁹Mo is consistent with a substitutional-interstitial mechanism. A correlation exists between the ratio of the ionic radius for the impurity and host and the measured activation energy for impurity diffusion. Very low diffusion rates are indicated at the operating temperatures of the Unclad Metal Breeder Reactor. The diffusion of Mo will be the most significant of the fission products studied. (DLC)

No abstract available

[en] The US/Japan agreement provided for sharing of Doublet III experimental time between scientific teams from GA and the Japan Atomic Energy Research Institute (JAERI), and also provided for upgrading the experimental capabilities of Doublet III with additional power systems, plasma heating capability, and plasma diagnostic systems

[en] A study was performed of the diffusion in α-thorium of fission products representing impurity atoms with a diversity of size and valence differences with respect to the solvent lattice. The atoms were recoil injected into thorium disks. Diffusion coefficients were determined for ¹³³Xe by monitoring its release during annealing, and for the other isotopes by post-annealing concentration profile analysis. The Arrhenius constants D₀(cm²/sec), resp. Q(kcal/mole) were obtained for the diffusion coefficients where, D=D₀ exp(-Q/RT);⁹⁹Mo: 7.6 X 10^-4 and 37.6; ¹³²Te: 1.32 X 10⁶ and 95.6; ¹³³I: 2.7 X 10^-1 and 66.2; ¹³³Xe: 3.6 X 10² and 82.3; ¹⁴⁰Ba: 2.3 X 10^-2 and 59.4; ¹⁴¹Ce - ¹⁴³Ce: 1.8 X 10^-2 and 60.0. The fission product diffusion behavior, in general, fit either the vacancy or the substitutional-interstitial diffusion mechanisms for impurity atoms in a fcc metal. Both valence and ionic radius correlations were found. The data indicate low rates of diffusion for the operating temperatures at which α-thorium-based fuel might be used. (Auth.)

[en] This paper discusses recent experience in steam generator testing for the Clinch River Breeder Reactor Plant (CRBRP). The experience includes testing of a Prototype Steam Generator Module at the Energy Technology Engineering Center and iterative testing of flow models (including a full-scale flow model) to confirm the hydraulic design of the CRBRP Steam Generator Modules. The objectives of the testing are presented together with descriptions of the test articles and testing facilities, and the test results are discussed. (author)