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JAEA Reports

Example of answers to the problems of the 37th examination for the chief engineer of nuclear fuel, 2005

Harada, Akio; Sato, Tadashi*; Nakajima, Kunihisa; Komuro, Yuichi; Shiraishi, Hirotsugu*; Hattori, Takamitsu; Ikuta, Yuko; Yachi, Shigeyasu; Kushita, Kohei

JAERI-Review 2005-026, 55 Pages, 2005/09

JAERI-Review-2005-026.pdf:1.95MB

This report provides an example of answers to the problems of the 37th Examination for the Chief Engineer of Nuclear Fuel. This examination was done as a national qualification in March 2005. Brief explanations or references are added to some answers.

JAEA Reports

Example of answers to the problems of the 36th examination for the chief engineer of nuclear fuel, 2004

Yachi, Shigeyasu; Nakamura, Jinichi; Amaya, Masaki; Nakajima, Kunihisa; Komuro, Yuichi; Nakajima, Katsuaki*; Kobayashi, Yasuhiko; Sato, Tadashi*; Suga, Shinichi*; Noguchi, Hiroshi; et al.

JAERI-Review 2004-020, 61 Pages, 2004/09

JAERI-Review-2004-020.pdf:1.85MB

This report provides an example of answers to the problems of the 36th Examination for the Chief Engineer of Nuclear Fuel. This examination was done as a national qualification in March 2004. Brief explanations or references are added to some answers.

JAEA Reports

Backfilling of the underground facilities on a disposal site

Sugita, Yutaka; Fujita, Tomoo; Tanai, Kenji; Hasegawa, Hiroshi; Furuichi, Mitsuaki*; Okutsu, Kazuo*; Miura, K.*

JNC TN8400 99-039, 58 Pages, 1999/11

JNC-TN8400-99-039.pdf:3.19MB

Regarding disposal techniques of high-level radioactive waste (HLW), the HLW is vitrified and then stored for cooling for a period of 30 to 50 years. After cooling, the HLW is isolated in the deep underground. The concept of geological disposal is based on the requirement to enclose the HLW in the deep underground for the long-term durability of the human's environmental safety. Backfilling of a repository is a unique activity on the geological disposal. If underground tunnels excavated to construct the repository are left, they may have significant influences on the barrier performance of an entire repository, such as: the mechanical stability of a tunnel may be damaged by rock stresses and a tunnel may provide a fast pathway for ground water flow. Therefore, the underground facilities are expected to be backfilled with a backfilling material after emplacement of the HLW and a buffer material. The material for the backfilling of the underground facilities is backfilling material. In this report, bentonite-aggregate mixture is considered, as one of the candidate materials for the backfilling material. Aggregate imitates the muck that is generated during construction phase of the underground facilities. The combination of backfilling, plugging and grouting is considered in some underground situations. Plug is composed of concrete material or clay-based one. Grouting material is concrete material or clay-based one, too. In this report, the concept of the backfilling, mechanical and hydrological characteristics of the bentonite-aggregate mixture, the function, work methods and a schedule of the backfilling materials, plugging and grouting are considered, and items of quality control for the bentonite-aggregate mixture, concrete material and grouting are listed.

JAEA Reports

None

PNC TN1410 97-032, 468 Pages, 1997/08

PNC-TN1410-97-032.pdf:10.35MB

no abstracts in English

JAEA Reports

Proceedings of the 25th anniversary meeting of the Alpha-Gamma facility

Kajitani, Yukio; ; Abe, Kazuyuki; Osaka, Masahiko; ; Hirosawa, Takashi; Koyama, Shinichi

PNC TN9440 97-004, 186 Pages, 1997/02

PNC-TN9440-97-004.pdf:21.19MB

The 25th anniversary meeting of the Alpha-Gamma Facility (AGF) at O-arai Engineering Center of PNC was held on February 7. The AGF started to examine irradiated materials on october 1 and fuel pins irradiated in the Dounreay Fast Reactor, DFR332/2 on December 1, 1971. The contents in this paper of the anniversary meeting are as follows. (1)25 years history and challenging plan for 2000 year. (2)Maintenance logbook of the facility, apparatus and manipulators for 25 years. (3)Recent results of melting temperature, thermal conductivity and lattice constants in irradiated MOX fuels. (4)Development on fission products release measuring apparatus and results of cold run tests. (5)Post irradiated examination results operated at the metallography cell in the Fuels Monitoring Facility (FMF). (6)Development on chemical analysis method for minor actinides (MA) in irradiated MOX fuels. (7)Refurbishment for MA containing MOX fuels, status and specifications for the fabrication and quality control apparatus.

JAEA Reports

A study on incubation time for erosion by high temperature sodium

Wakai, Takashi; Aoto, Kazumi

PNC TN9420 97-003, 11 Pages, 1996/12

PNC-TN9420-97-003.pdf:0.36MB

Generally, it is required several periods for the damage initiation due to erosion. Such periods are called incubation time. This report describes the calculation of incubation time for erosion of a carbon steel subjected to dripping liquid sodium at elevated temperature, assuming fatigue plays the significant role in the early stage of erosion. It is clalified that the incubation time is remarkably long and it is needless to consider the damage due to erosion if there is no material property degradation. However, taking the material property degradation of carbon steel and liquid sodium into account, the incubation time may be short less than 1 hour in the most pessimistic case. So in this case, erosion must be considered as one of the damage mechanisms of carbon steel.

JAEA Reports