Annual Report - Volume 27 (2007)

Review

1. Tritium Handling in Laser Fusion Research
   

   Y.Izawa

   
   

Original

2. Isotope Effect on Methane Decomposition observed between CH₄ and Cd₄ over Zr

   K. Watanabe, W Shu, M. Matsuyama

   
   
3. Absorption and Release of Hydrogen Isotopes by ZrC
   

   Y. Hatano, T. Nozaki, H. Homma, M. Matsuyama

   
   
4. Thermodynamic properties of Pd-Ag hydride and that deuteride

   M.Hara, K.Hashizume, K.Watanabe, T.Okabe, M.Matsuyama

   
   
5. Temperature Dependence of the Tritium Release Behavior from SS316

   S.Naoe, Y.Torikai, K.Akaishi, R-D. Penzhorn, K. Watanabe, M. Matsuyama

   
   
6. Application of discrete element method to analysis of coating process on powdery materials in barrel-sputtering system

   S.Akamaru, H.Yamamoto, A.Taguchi, T.Abe

   
   

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Annual Report27-1
Review

 Progresses and future prospect of laser fusion research and developments of tritium handling techniques for laser fusion are reviewed. Implosion physics of laser fusion targets toward central ignition has been intensively investigated for more than 30 yeays. Numerous milestones such as high density compression and heating of fusion fuel habe been achived. Recently a new scheme named fast ignition is opened by the development of highly intensive laser technology. Both by the central ignition and the fast ignition schemes, fusion ignition and burn will be demonstrated in the near future. Since the early stage of laser fusion reserch, DT fuel has been introduced in the implosion experiments. Numerous techniques, such as DT gas filling over 1000 atmospheric pressure into the glass and plastic shell targets, formation of uniform cryogenic DT layer on the inner wall of shell target, cleaning of target chamber wall and recovery system of DT fuel after the experiments, and safety system to preclude accidental release of DT gas and to minimize the potential for exposures to personnel, have been developed.

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Annual Report27-1
Original

The decomposition of methane and deutero-methane(CD₄)over Zr,Zr₄Ni was investigated to develop highly active materials for capturing tritiated methane inevitablly formed in tritium handling systems. None of the decomposition or absorption curves could be described by a series reaction scheme including growth of carbonaceous deposits on the surface. The reaction mechanisms were studied in more detail in the present study, and it was revealed that the absorption / decompositon of methane proceeds via the steps CH₄(g)^k1→CH₃(a)^k2→ CH₂(a)^k3→C–deposits.  The kinetic isotope effect on the decomposition using small clusters including two or three Zr atoms.

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Annual Report27-3
Original

Interaction between hydrogen isotopes and ZrC powder was examined at 873 K and pressure from 0.89 to 99 Pa. Reversible absorption and release of hydrogen isotopes were observed. The equilibrium concentrations of hydrogen isotopes in the above pressure range were from 82 to 120 mol ppm; the pressure dependence observed was much weaker than that expected from Sieverts' law. The diffusivity of hydrogen was evaluated to be 5×10^–16m²•s^–1 by assuming that powder particles were spherical with diameters of 1 μm.

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Annual Report27-4
Original

Thermodynamic properties of Pd-Ag hydride and its deuteride were evaluated by pressure-composition isotherms. Every isotherm for various Pd-Ag alloys showed a platesu region, whereas the slope of the plateau increased with increasing silver contents. On the other hand, the equilibrium pressure of the plateau region at [Q,Q=H, D]/ [Pd-Ag]=0.2 decreased with increasing silver contents.This indicated that the added hydride formation entropies for hydrogen was larger than that for deuteride. It could not be explained in term of the difference between the entropy of hydrogen gas and that of deuterium.

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Annual Report27-5
Original

Release rates of tritium from stainless steel 316 were measured in the temperature range 283 -573 K and depth profiles of tritium in thermally depleted specimens were obtained by chemical etching procedures. The release results were interpreted using a one-dimensional diffusion model. The activation energy for the diffusion of tritium through stainless steel was found to be 61.3kj/mol. This value is well in line with other values reported in the literature.

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Annual Report27-6
Original

In order to analyze the coating process on powdery materials in a barrel-sputtering system, we developed a simulation program based on the discrete element method. The flow of particles during barrel rotation was reproduced by the simulation. The coating process was calculated by a simple coating model. The calculated results qualitatively represented the difference for coating process between the hexagonal and the round barrel. It was also found that the particles surface was uniformly coated by using the hexagonal barrel.