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Deep geologic repository progress—2025 Update
Editor's note: This article has was originally published in November 2023. It has been updated with new information as of June 2025.
Outside my office, there is a display case filled with rock samples from all over the world. It contains a disk of translucent, orange salt from the Waste Isolation Pilot Plant near Carlsbad, N.M.; a core of white-and-bronze gneiss from the site of the future deep geologic repository in Eurajoki, Finland; several angular chunks of fine-grained, gray claystone from the underground research laboratory at Bure, France; and a piece of coarse-grained granite from the underground research tunnel in Daejeon, South Korea.
G. C. Abell, A. Attalla
Fusion Science and Technology | Volume 14 | Number 2 | September 1988 | Pages 643-648
Tritium Properties and Interactions with Material | Proceedings of the Third Topical Meeting on Tritium Technology in Fission, Fusion and Isotopic Applications (Toronto, Ontario, Canada, May 1-6, 1988) | doi.org/10.13182/FST88-A25207
Articles are hosted by Taylor and Francis Online.
This paper presents Nuclear Magnetic Resonance (NMR) studies of aging phenomena in palladium tritide. 3He NMR relaxation parameters have been measured as a function of temperature for 6-, 13-, and 22-month-old beta phase palladium tritide. The most significant result of this study is the observation of a solid/fluid phase transition near 250 K of 3He that has accumulated in the PdTx substrate via triton decay. Although the existence of solid helium at relatively high temperatures had been predicted for helium in metals, it had not previously been confirmed in any metal/helium system. The observed melting temperatures, together with the known equation of state for 4He, allow a determination of the helium density as a function of age. The atomic density obtained in this way is approximately 2.0 times that of palladium metal, agreeing with densities inferred from dilatometric measurements of other metal tritides and also with predictions based on the concept of dislocation loop punching by highly overpressurized He bubbles. The 3He signal in the 22-month-old sample was sufficiently strong to allow a detailed study of melting as a function of temperature, and provides information on the distribution of densities over the ensemble of bubbles.