Development of measuring device for inner surfaces of embedded piping (Contract research)

Ito, Hirokuni*; Hatakeyama, Mutsuo*; Tachibana, Mitsuo; Yanagihara, Satoshi

JAERI-Tech 2003-012, 34 Pages, 2003/03

JAERI-Tech-2003-012.pdf:2.87MB

The MISE was developed to evaluate low-level radiological contaminations of inner surfaces of piping. The MISE consists of a cylindrically-formed double layered type detector and a piping crawling robot, which were designed and manufactured separately. In measurements of the contaminations, an outer cylindrical detector close to the surface of piping measures -rays and -rays and an inner cylindrical detector set after a shielding plate for shield of -rays measures -rays. The -ray counting rates are derived by subtracting -ray counts measured by the inner detector from - and -ray counts measured by the outer detector. The robot transports the double layered type detector with observing inner surfaces of piping. The detection limit for the contamination of Co was found to be about 0.17Bq/cm with measurement time of 30 seconds. It is expected that 0.2Bq/cm corresponding to clearance level of Co (0.4Bq/g) can be evaluated with measurement time of 2 seconds, which is equal to measurement speed of 54m/h.

Study of aerosol diffusion behaviors in dismantling nuclear facilities (Contract research)

Shimada, Taro; Tachibana, Mitsuo; Yanagihara, Satoshi

JAERI-Tech 2001-060, 44 Pages, 2001/09

JAERI-Tech-2001-060.pdf:5.11MB

To evaluate aerosol diffusion behaviors under dismantling of nuclear facilities, plasma arc cuttings were conducted in the enclosure. The flow of air and high temperature gas in the enclosure were visualized, and the temperature distributions in the enclosure and the aerosol number and weight density in air of outlet flow were measured in the experiments. As a result, it was confirmed that ascending high temperature gas flow produced by the plasma arc is corresponded with aerosol diffusion behavior during cutting. It was also confirmed that after completing the cuttings the aerosol tends to fall due to decreasing of flow velocity of high temperature gas and the aerosol which reaches near the floor is resuspended by relatively high velocity exhaust flow.

Nuclear criticality safety handbook, 2; English translation

Working Group on Nuclear Criticality Satety Data

JAERI-Review 2001-028, 217 Pages, 2001/08

JAERI-Review-2001-028.pdf:10.04MB

no abstracts in English

Mobile robot with a self-positioning system

Yanagihara, Satoshi; Hatakeyama, Mutsuo; Ito, Hirokuni; Mori, Shunji*; Takagi, Akira*

Advanced Robotics, 15(3), p.293 - 300, 2001/06

https://doi.org/10.1163/156855301300235805

Automatic measurement of building surface radioactivity must be a useful approach for decommissioning and maintenance activities in nuclear facilities. In particular, in the final step of decommissioning a nuclear power plant, it is essential to confirm that there is no effective radioactivity on building surfaces by measurement. However, experience showed that hands-on measurement using conventional detectors requires a great deal of labor-hours for all building surfaces in relatively large facilities. To realize the automatic measurement of building surface radioactivity, a mobile robot equipped with highly sensitive surface detectors has been developed; it can move automatically based on route plans to measure radioactivity on concrete floors and walls. In the development of this system, efforts were especially made to realize accurate robot motions by applying self-position identification system in consideration of the fact that the measurement should cover all the surfaces of planned areas with minimum overlap.

Mock-up test of remote controlled dismantling apparatus for large-sized vessels (Contract research)

Myodo, Masato; Okane, Shogo; Miyajima, Kazutoshi

JAERI-Tech 2001-025, 59 Pages, 2001/03

JAERI-Tech-2001-025.pdf:4.73MB

no abstracts in English

Lessons learned from remote dismantling activities of JPDR (Contract research)

Tachibana, Mitsuo; Shiraishi, Kunio; Yanagihara, Satoshi

JAERI-Tech 2001-014, 42 Pages, 2001/03

JAERI-Tech-2001-014.pdf:2.4MB

In the JPDR dismantling demonstration project, the dismantling activities were conducted for the purpose of verification of remote dismantling machines and collection of various kinds of data on work activities. These lessons were categorized into safety consideration, waste treatment and work efficiency by analyzing the data on work activities. Exemplified are necessities of facility information, efficiency of mock-up tests for evaluation of remote dismantling procedures. There will be useful for implementing other decommissioning projects in safe and efficiency. This report describes the measure taken for remote dismantling activities and the lessons learned from the dismantling activities.

Data report of BWR post-CHF tests; Transient core thermal-hydraulic program (Contract research)

Iguchi, Tadashi; Ito, Hideo; Kiuchi, Toshio; Watanabe, Hironori; Kimura, Mamoru*; Anoda, Yoshinari

JAERI-Data/Code 2001-013, 502 Pages, 2001/03

JAERI-Data-Code-2001-013.pdf:32.38MB

no abstracts in English

Melting behavior of low-level radioactive miscellaneous solid waste and characteristics of solidified products (Contract research)

Nakashio, Nobuyuki; Isobe, Motoyasu; Wakui, Takuji*; Iwata, Keiji*; Kibayashi, Tatsuyuki*; Kanazawa, Katsuo; Fukui, Toshiki; Otake, Atsushi*; Nakashima, Mikio; Hirabayashi, Takakuni*

JAERI-Research 2001-001, 19 Pages, 2001/02

JAERI-Research-2001-001.pdf:1.29MB

no abstracts in English

Feasibility study on floating nuclear power plant, 1; Conceptual design study of FNPP (Contract research)

Yabuuchi, Noriaki; Takahashi, Masao*; Nakazawa, Toshio; Sato, Kazuo*; Shimazaki, Junya; Ochiai, Masaaki

JAERI-Research 2000-063, 69 Pages, 2001/02

JAERI-Research-2000-063.pdf:4.41MB

no abstracts in English

Correlation between cleavage fracture toughness and charpy impact properties in the transition range of reactor pressure vessel steels

Onizawa, Kunio; Suzuki, Masahide

Proceedings of Asian Pacific Conference on Fracture and Strength '01(APCFS '01) and International Conference on Advanced Technology in Experimental Mechanics '01 (ATEM '01), p.140 - 145, 2001/00

In the structural integrity assessment of reactor pressure vessel, fracture toughness values are estimated by assuming that the radiation effect on fracture toughness is equivalent to that on Charpy properties. Therefore, it is necessary to establish the correlation between both properties especially on irradiation embrittlement. In this paper, we present the fracture toughness data obtained by applying the master curve approach that was adopted recently in the ASTM test method. Materials used in this study are five ASTM A533B class 1 steels and one weld metal. Neutron irradiation for Charpy-size specimens as well as standard Charpy-v specimens was carried out at the Japan Materials Testing Reactor. The shifts of the reference temperature on fracture toughness due to neutron irradiation are evaluated. Correlation between the fracture toughness reference temperature and Charpy transition temperature is established. Based on the correlation, the optimum test temperature for fracture toughness testing and the method to determine a lower bound fracture toughness curve are discussed.