About the Design of the Cover


The cover is designed with white hexagons similar to the pattern in a tortoise shell, an ancient Japanese symbol of people’s wish for longer lives. Coincidentally, this shape is the same as that of core fuel assemblies for both the prototype fast breeder reactor “MONJU” and the high-temperature engineering test reactor “HTTR”.


The images on the cover show results of the air cooling simulation for simplified debris (top left) and drilling machine for large diameter pit (bottom right).


The top left image shows the simulation results of the heat transfer between the simplified debris and the gas phase induced by the natural convection. Fuel debris is simplified as the plate and half sphere shape and is considered the decay heat as the heat generation (Chapter 1, Topic 1-5, p.15).


The bottom right image shows the drilling machine for large diameter pit, which was developed and produced in order to excavate a pit for EBS test at Horonobe URL. The machine combines casing drilling and auger excavation, and allows continuous drilling of a disposal pit in a soft sedimentary rock (Chapter 8, Topic 8-5, p.82).


JAEA R&D Review 2017

annual report 2017

About the activity status of the whole agency
including CSR, see the annual report
Japan Atomic Energy Agency 2017

JAEA R&D Review 2017–18

Published by
Japan Atomic Energy Agency in January 2018
Editorial Board
Chief editor:Hideaki Mineo

Junya Sumita, Tomoaki Suzudo, Ayako Okubo, Shinichi Noguchi,
Tadafumi Niizato, Takeshi Takeda, Shinichi Shamoto, Takamasa Mori,
Terufumi Yokota, Shoji Takada, Taiju Shibata, Hiroshi Takada, Takashi Takata,
Yoshikazu Yamada, Masanori Ando, Kazuhiko Sato, Chie Oda

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