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Amaya, Masaki
no journal, ,
The objectives of the fuel safety research program at JAEA are to evaluate the adequacy of present safety criteria and safety margins, to provide a database for the regulation on improved fuels using new materials of cladding and pellet, and to provide reasonably mechanistic computer codes for regulatory application, in terms of light water reactor fuel. In this presentation, in addition to recent progress in the reactivity-initiated accident (RIA) and loss-of-coolant accident (LOCA) test programs, an overview of the current status of the fuel safety research at JAEA is described.
and ZrOTakaki, Seiya
no journal, ,
Oxide ceramics with fluorite-structure have been studied as advanced nuclear application, so it is important to clarify the irradiation-induced microstructure. Especially, radiation damage induced by fission fragments with 70-100 MeV, induce high-density electronic excitation in the materials to result in forming cylindrical defect, so called ion track. This study aims to clarify and compare with the structure of ion tracks in CeO and cubic ZrO (YSZ) irradiated with swift heavy ions. It was shown that the density of vacancy at the core damage region of ion tracks is increased and the O anion lattice is preferentially disordered at such region. On the other hand, the size and the areal density of ion tracks in YSZ is smaller than those of CeO. The difference of ion tracks between CeO and YSZ is presumably due to the difference in the recovery process from the thermal spike regime, which is influenced by the presence of structural vacancy in oxide sublattice.
Tokushima, Kazuyuki; Shirasu, Noriko; Hoshino, Kuniyoshi*; Ohara, Hiroshi*; Kurata, Masaki
no journal, ,
At the fuel assembly degradation stage in severe accidents, chemical features of the intermediate products are expected to be changed depending upon the accident progressions. These differences are originated from the differences in oxygen potential and temperature, and are highly important for evaluating the relocation and stratification progress of the fuel debris. Two types of sim-test with the different oxygen potentials were performed to investigate these tendencies. The chemical features of the intermediate materials used in the tests were determined from the observations for the control blade and channel box degradation in our previous study. The present results indicate that the U concentration in the metallic layer is largely varied depending upon the oxygen potential of the atmosphere. Also, when the B
C-Fe alloy, as of a typical intermediate product, coexists with UO and Zr, the apparent red-ox reaction rate between UO and Zr are mitigated.
Sudo, Ayako
no journal, ,
no abstracts in English
Nagase, Fumihisa
no journal, ,
As the lesson learned from the accident at the Fukushima Daiichi Nuclear Power Station, fuel components with enhanced accident tolerance are developed inside and outside Japan. It is required for the development to utilize intelligence, technologies, experiences, tools, and human resources accumulated, taking account of the particularity of the LWR fuel. This presentation introduces the definition of technical readiness levels created for efficient development, the evaluated influence of use of accident tolerant fuel components on core and plant design, fuel behavior and design, and accident progression, and the attribute guide which were obtained in cooperation with industry and universities.
Miwa, Shuhei
no journal, ,
We investigate the sintering behavior of inert matrix fuel with magnesium oxide containing americium. We found that the high density of inert matrix fuel could achieve by adjusting sintering kinetics of magnesium oxide and americium oxide which was governed by oxygen potential. Based on this result, we established fundamental fabrication process flow of inert matrix fuel with magnesium oxide.