Effects of neutron irradiation on some superplastic characteristics of tetragonal zirconia polycrystals containing 3 mol% yttria

Shibata, Taiju; Ishihara, Masahiro; Motohashi, Yoshinobu*; Ito, Tsutomu*; Baba, Shinichi; Kikuchi, Makoto*

Materials Transactions, 45(8), p.2580 - 2583, 2004/08

https://doi.org/10.2320/matertrans.45.2580

Fast neutrons (energy 1.610 J) were irradiated to tetragonal zirconia polycrystals containing 3 mol% yttria (3Y-TZP) at the fluence levels of 2.510 (Light irradiation) and 4.310 (Heavy irradiation) m. The irradiation caused no significant swelling in the 3Y-TZP specimens. After the neutron irradiation, superplastic characteristics were examined by tensile tests at a temperature range from 1623 to 1773 K with initial strain rates ranging from 5.010 to 1.6710s. It was found that the elongation to fracture of the irradiated specimens was quite small in comparison with the unirradiated ones. The apparent activation energy for the superplastic flow of the irradiated 3Y-TZP was fairly high, i.e., 781 and 693 kJ・mol for Light and Heavy irradiations, respectively. Atomic displacement damages and defects in the 3Y-TZP caused by the irradiation were thought to be main causes of these property changes.

Development of radiation-hard ultrasonic inspection probes for ITER vacuum vessel

Koizumi, Koichi; Nakahira, Masataka; Oka, Kiyoshi; Obara, Kenjiro; *; Morita, Yosuke; Tada, Eisuke

JAERI-Tech 96-041, 66 Pages, 1996/10

JAERI-Tech-96-041.pdf:2.6MB

no abstracts in English

Chromosome dynamics and cyclic change of cell life and death

Ouchi, Noriyuki

no journal, , 

Radiation sensitivity via cell survival shows cyclic radiation response, i.e. minimal when cells are irradiated in the early post-mitotic (G1) and the pre-mitotic (G2) phases of the cell cycle, and maximal in the mitotic (M) phase and late G1 or early synthesis (S) phases. Origin of the cell-cycle dependent radiation sensitivity is supposed to be a consequence of some intra-cellular dynamics, e.g. regulation mechanism of cell-cycle checkpoint, repair ability of DNA damage and higher order structure of chromosomes, no explicit theoretical explanation exists on this cyclic response yet. Here, cell-cycle dependent radiation sensitivity is studied from the viewpoints of dynamical aspects of chromosome in association with its cell-cycle dependent structural changes. For this purpose, dynamical model of chromosome is mathematically constructed based on the elastic nature of chromosomes and its radiation effects are simulated by introducing DNA double strand break (DSB) to the model.