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The thermal conductivity of sintered pellets of plutonium and americium oxides was measured with a longitudinal heat flow method at 60 C in the freshly sintered state and at variable intervals after up to 3 years storage time. The conductivity decreased due to defects created by alpha particles from decaying 239Pu- and 241Am-nuclides until saturation was reached after 3 days in the case of americium oxide and after 200 days for PuO(2). The plutonium oxide sample, after 1030 days of storage at room temperature, was then annealed in seven temperature steps up to 800 C. A recovery stage could be observed around 250 C and recovery to the freshly sintered state occurred around 800 C. From the rate of change in lambda, a defect saturation concentration can be estimated above which the thermal conductivity of the material measured under the above conditions is no longer affected. It is supposed that defect clusters are formed at higher self-irradiation doses, and that their phonon scattering cross-sections are, to a certain extent, independent of the number of coalescing defects.

Additional information

Authors: SCHMIDT H E, JRC Karlsruhe (DE);RICHTER J, JRC Karlsruhe (DE);VAN GEEL J, JRC Karlsruhe (DE)
Bibliographic Reference: Paper presented: 22nd International Thermal Conductivity Conference, Tempe, Arizona (US), November 7-10, 1993
Availability: Available from (1) as Paper EN 37991 ORA
Record Number: 199410071 / Last updated on: 1994-11-28
Original language: en
Available languages: en