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Various perfluorinated materials are used at the Princeton Plasma Physics Laboratory in support of the Deuterium-Tritium experimental program on the Tokamak Fusion Test Reactor (TFTR). For example, SF{sub 6} is used as a high dielectric gaseous insulator in the Neutral Beam sources, and Krytox, a perfluorinated polyether, is used as a lubricant in vacuum pumping systems. Each of these materials is robust and stable in the applications for which they are designed but may be a source of trouble when used in tritium systems. This paper reports on the observations made and experience gained operating tritium systems under conditions which degrade these perfluorinated materials. The possible degradation mechanisms and products are described, and the effect on the equipment and instrumentation is described. These observations have led to the conclusion that under certain circumstances perfluorinated materials are not suited for tritium service because of the degradation products from tritium decay and/or process conditions. 11 refs., 1 fig., 1 tab.

Palladium and LaNi5-xAlx (x=0.30, 0.75, 0.85), which form reversible hydrides, are used for tritium processing and storage in the Savannah River Site (SRS) tritium facilities. As part of a program ...

Helium from tritium decay causes the desorption isotherm plateau pressure for LaNi4.25Al0.75 tritide to be lowered. From the shape of the 3He altered isotherm, it appears that the material becomes disordered and possibly disproportioned. The microstructure of the parent LaNi4.25Al0.75 tritide material is believed to influence the behavior of 3He from tritium decay.

Intermetallic compounds which react with hydrogen isotopes to form reversible hydrides offer several advantages for storing and processing tritium. Advantages include safe, low pressure, high density storage, and delivery of high purity 3He-free tritium without the use of pumps. As part of a program to devleop metal hydride technology for storing and processing tritium, the effects of tritium aging on the thermodynamic behavior of the tritides are under investigation. During aging of LaNi4.25Al0.75 tritides, the 3He decay product of tritium produced in the lattice does not leave the lattice but causes changes in the thermodynamics of the gas-solid system. Among the changes noted are (1) decreased tritium desorption pressures, (2) increased slopes of desorption isotherm plateaux and (3) small quantities of irreversibly-held tritium. Absorption-desorption cycling and brief heating of samples to 350°C while loaded with deuterium partially reverses these effects. While the desorption isotherms of tribium-aged LaNi4.25Al0.75 tritides resemble the desorption isotherms of amorphous hydrogen storage materials, X-ray diffraction patterns of tritium-aged samples after desorption of tritium do not exhibit the characteristics of an amorphous material. The diffraction patterns show broadening and anisotropic effects that suggest the presence of lattice strains and orientational effects of 3He in the LaNi4.25Al0.75 lattice. Self-interstitials, dislocations and bubbles are probably present in the aged samples.

Helium dynamics in La-Ni-Al tritides have been observed by measuring the plateau pressure decrease for the pressure of tritium in equilibrium with the solid as a function of helium composition. Calculations suggest that a crystal lattice volume expansion, caused by helium, stabilizes the tritide. Temperature cycling the helium-altered, tritium-saturated intermetallic partially restores the plateau pressure. These data are discussed in the context of immobile helium which can gain mobility as the tritide ages.

The absorption spectrum of PuF 6 is investigated using a long-pass multiple reflection cell. Cross sections over the spectral region of 3000–9000 A are reported. Due to the enhanced sensitivity of our apparatus the wavelengths and absorption cross sections are significantly improved over the previously available data.