Handling of HTTR second driver fuel elements in assembling and storage working

Tomimoto, Hiroshi; Kato, Yasushi; Owada, Hiroyuki; Sato, Nao; Shimazaki, Yosuke; Kozawa, Takayuki; Shinohara, Masanori; Hamamoto, Shimpei; Tochio, Daisuke; Nojiri, Naoki; et al.

JAEA-Technology 2009-025, 29 Pages, 2009/06

JAEA-Technology-2009-025.pdf:21.78MB

The first driver fuel of the HTTR (High Temperature Engineering test Reactor) was loaded in 1998 and the HTTR reached first criticality state in the same year. The HTTR has been operated using the first driver fuel for a decade. In Fuel elements assembling, 4770 of fuel rods which consist of 12 kinds of enrichment uranium are loaded into 150 fuel graphite blocks for HTTR second driver fuel elements. Measures of prevention of fuel rod miss loading, are employed in fuel design. Additionally, precaution of fuel handling on assembling are considered. Reception of fuel rods, assembling of fuel elements and storage of second driver fuels in the fresh fuel storage rack in the HTTR were started since June, 2008. Assembling, storage and pre-service inspection were divided into three parts. The second driver fuel assembling was completed in September, 2008. This report describes concerns of fuel handling on assembling and storage work for the HTTR fuel elements.

Deformation history of sackung features concentrated around the northern tip of the active Neodani fault, central Japan

Komura, Keitaro*; Kaneda, Heitaro*; Kashihara, Shintaro*; Nishio, Tomohiro; Kojima, Satoru*

no journal, , 

Recent high-resolution airborne LiDAR revealed that many sackung features are concentrated around the northern tip of the active Neodani fault, central Japan. These features are hidden under forest canopies, and thus high-precision dating of slope deformation episodes would be possible by radiocarbon dating. In order to examine the relationship between the fault activity and the formation/growth of the sackung features, we conducted hand corings and pit excavations at two sites out of the many sackung depressions found adjacent to the Neodani fault. Our results revealed that the sackung scarps experienced multiple growth events after ~5 ka and the latest event might have occurred simultaneously with the 1891 Nobi earthquake, suggesting that local earthquakes from adjacent active faults are important trigger of formation and growth of those sackung features. We suggest that detailed study of selected sackung features adjacent to an active fault may contribute to reconstruct local paleoseismic history.

Aging effect for hydrogen embrittlement behavior on Ta-Zr alloy

Kaneda, Tomohiro*; Yokoyama, Kenichi*; Ishijima, Yasuhiro; Ueno, Fumiyoshi; Abe, Hitoshi

no journal, , 

In spent nuclear fuel reprocessing plant, Zr/Ta dissimilar metal joint is used for connect between different devices. And it is known that Zr and Ta have susceptibility of hydrogen embrittlement. The other hand, Zr and Ta are alloyed in the dissimilar joint and it is not clear that the hydrogen embrittlement behavior of the Zr-Ta alloy. This study aims to elucidate the hydrogen embrittle behavior of the Zr-Ta alloy. Tensile tests and X-ray diffraction (XRD) were carried out after hydrogen charging in 0.9% NaCl solution. The zirconium hydride was detected by XRD analysis but embrittlement was not shown by tensile tests. However, brittle fracture patterns were observed by SEM observation at the fracture surface the specimen after tensile test. It is consider that these results suggest the zirconium hydride that formed by hydrogen charging dominates the hydrogen embrittlement behavior of the Zr-Ta alloy.