Inspection and repair techniques in reactor vessel of the experimental fast reactor JOYO; Development of devices for retrieving bent MARICO-2 subassembly and completion of retrieval work

Ashida, Takashi; Nakamura, Toshiyuki*; Ito, Hideaki

JAEA-Technology 2017-024, 198 Pages, 2017/11

JAEA-Technology-2017-024.pdf:55.8MB
JAEA-Technology-2017-024-appendix(CD-ROM)-1.zip:298.09MB
JAEA-Technology-2017-024-appendix(CD-ROM)-2.zip:210.77MB

In the experimental fast reactor Joyo, the disconnecting of an irradiation test subassembly MARICO-2 (Material Testing Irradiation Rig with Temperature Control) from its holding mechanism was conducted in May 2007. After the operation, the rotating plug was rotated despite the fact that the test subassembly was not disconnected completely. Consequently, top of wrapper tube of the MARICO-2 subassembly was bent onto the in-vessel storage rack. Since the overhanging part of the subassembly was in the height in which contacts with the upper core structure, it had damaged the bottom surface of the upper core structure. As the result, it was necessary to replace the damaged upper core structure and to retrieve the bent MARICO-2 subassembly for Joyo restart. Retrieval devices for MARICO-2 subassembly consist of a gripper mechanism to lift subassembly together with transfer pot, a guide tube built-in a pantograph mechanism to adjust lifting axis and safety mechanisms to prevent or mitigate falling of MARICO-2 subassembly, a retrieval cask and so on. Design of the retrieval devices have been verified in ex-vessel partial or full-scale mock-up tests and in-vessel function tests. In 2014, MARICO-2 subassembly was successfully retrieved from the reactor vessel by applying these retrieval devices. Then, retrieved subassembly was transported to a hot-cell facility for post-irradiation examinations. Devices have demonstrated expected performance under the actual environmental conditions of a sodium cooled fast reactor. This is a synthetic report about the retrieval work of the deformed and irradiated test subassembly in Joyo. This report includes the detail design and fabrication of the special retrieval device, results of tests for confirmation including the mock-up tests in manufacturer's factory, and results of MARICO-2 retrieval work from the reactor vessel.

Activities for revising Nuclear Criticality Safety Handbook

Okuno, Hiroshi; Nomura, Yasushi

Proceedings of the 2001 Topical Meeting on Practical Implementation of Nuclear Criticality Safety (CD-ROM), 8 Pages, 2001/11

The nuclear criticality safety handbook of Japan was first published in 1988, which was translated into English in 1995. This paper intends to introduce the American community of nuclear criticality safety to activities for revising the Japanese handbook, putting an emphasis on practical use of code validation. They include (1) publication of "Nuclear Criticality Safety Handbook, Version 2" and its English translation, (2) publication of "A Guide Introducing Burnup Credit, Preliminary Version," and (3) preparation of "Nuclear Criticality Safety Handbook, -Data Collection-, Version 2."

Fluctuations in the random-field Ising model

Journal of Physics; Condensed Matter, 10(23), p.5179 - 5186, 1998/00

https://doi.org/10.1088/0953-8984/10/23/018

no abstracts in English

Preparation for the 2nd edition of nuclear criticality safety handbook

; Nomura, Yasushi

Nihon Genshiryoku Gakkai-Shi, 39(10), p.832 - 841, 1997/00

https://doi.org/10.3327/jaesj.39.832

no abstracts in English

On the randomness of a transverse field for the Ising model

Physics Letters A, 171, p.134 - 136, 1992/11

https://doi.org/10.1016/0375-9601(92)90146-D

no abstracts in English

Preparations for revising the criticality safety handbook of Japan

Okuno, Hiroshi; Komuro, Yuichi; Naito, Yoshitaka

Proc. of the CSNI Specialist Meeting on Safety and Risk Assessment in Fuel Cycle Facilities, p.103 - 109, 1991/00

no abstracts in English

Radiative electron-capture processes in zero- and one-electron heavy-ion collisions with He

*; Kawatsura, Kiyoshi; P.Richard*

Physical Review A, 26(1), p.154 - 161, 1982/00

https://doi.org/10.1103/PhysRevA.26.154

no abstracts in English