High temperature mechanical properties and microstructure in 9Cr or 12Cr oxide dispersion strengthened steels

Mitsuhara, Masatoshi*; Kurino, Koichi*; Yano, Yasuhide; Otsuka, Satoshi; Toyama, Takeshi*; Onuma, Masato*; Nakashima, Hideharu*

Tetsu To Hagane, 109(3), p.189 - 200, 2023/03

https://doi.org/10.2355/tetsutohagane.TETSU-2022-080

Oxide Dispersion Strengthened (ODS) ferritic steel, a candidate material for fast reactor fuel cladding, has low thermal expansion, good thermal conductivity, and excellent resistance to irradiation damage and high temperature strength. The origin of the excellent high-temperature strength lies in the dispersion of fine oxides. In this study, creep tests at 700 or 750C, which are close to the operating temperatures of fast reactors, and high-temperature tensile tests at 900 to 1350 C, which simulate accident conditions, were conducted on 9Cr ODS ferritic steels, M11 and MP23, and 12Cr ODS ferritic steel, F14, to confirm the growth behavior of oxides. In the M11 and F14 creep test samples, there was little oxide growth or decrease in number density from the initial state, indicating that dispersion strengthening by oxides was effective during deformation. After creep deformation of F14, the development of dislocation substructures such as dislocation walls and subgrain boundaries was hardly observed, and mobile dislocations were homogeneously distributed in the grains. The dislocation density increased with increasing stress during the creep test. In the high-temperature ring tensile tests of MP23 and F14, the strength of both steels decreased at higher temperatures. In MP23, elongation decreased with increasing test temperature from 900 to 1100 C, but increased at 1200 C, decreased drastically at 1250 C, and increased again at 1300 C. In F14, elongation decreased with increasing temperature. It was inferred that the formation of the -ferrite phase was responsible for this complex change in mechanical properties of MP23 from 1200 to 1300 C.

Advanced non-destructive analysis technique capable of rapidly determining uranium mass contained in waste drum with high accuracy

Ozu, Akira; Komeda, Masao; Kureta, Masatoshi; Nakatsuka, Yoshiaki; Nakashima, Shinichi

Nihon Genshiryoku Gakkai-Shi ATOMO, 59(12), p.700 - 704, 2017/12

no abstracts in English

Development of non-destructive assay system using fast neutron direct interrogation method for actual uranium waste drums

Ozu, Akira; Komeda, Masao; Kureta, Masatoshi; Zaima, Naoki; Nakatsuka, Yoshiaki; Nakashima, Shinichi

Nihon Genshiryoku Gakkai Wabun Rombunshi, 15(2), p.115 - 127, 2016/06

https://doi.org/10.3327/taesj.J15.011

A non-destructive assay system using the fast neutron direct interrogation method has been developed to put its method into practical use for the determination of uranium (U) mass contained in actual uranium-contaminated waste drums. The method is capable of measuring the fissile mass in a drum by counting the number of fission neutrons resulting from nuclear fission reactions between the fissile materials contained in a drum and thermal neutrons generated by 14 MeV fast neutrons irradiated from outside the drum. The performance test employing simulated metal waste drums demonstrated that a natural uranium mass of as low as 10 g could be detected within an error of 20% regardless of the distribution of uranium samples in the drum. A demonstration test employing actual waste drums could determine the uranium mass by using a newly developed correction method for deriving the fissile mass in a drum. It has been proved by the experimental validation tests that the assay system equipped with the correction method is very useful for the accountancy of the waste drums.

Overview of particle and heavy ion transport code system PHITS

Sato, Tatsuhiko; Niita, Koji*; Matsuda, Norihiro; Hashimoto, Shintaro; Iwamoto, Yosuke; Furuta, Takuya; Noda, Shusaku; Ogawa, Tatsuhiko; Iwase, Hiroshi*; Nakashima, Hiroshi; et al.

Annals of Nuclear Energy, 82, p.110 - 115, 2015/08

https://doi.org/10.1016/j.anucene.2014.08.023

The general purpose Monte Carlo Particle and Heavy Ion Transport code System, PHITS, is being developed through a collaboration of several institutes in Japan and Europe. The Japan Atomic Energy Agency is responsible for managing the entire project. PHITS can deal with the transport of nearly all particles, including neutrons, protons, heavy ions, photons, and electrons, over wide energy ranges using various nuclear reaction models and data libraries. This paper briefly summarizes the physics models implemented in PHITS, and introduces some important functions useful for particular purposes, such as an event generator mode and beam transport functions.

Analytical study on uranium measurement in uranium waste drums by the fast neutron direct interrogation method

Komeda, Masao; Ozu, Akira; Haruyama, Mitsuo; Takase, Misao*; Kureta, Masatoshi; Nakatsuka, Yoshiaki; Zaima, Naoki; Nakashima, Shinichi; Otsuka, Yoshimasa

Proceedings of INMM 55th Annual Meeting (Internet), 9 Pages, 2014/07

We have researched and developed the FNDI method for a long time through experiments in NUCEF in JAEA Tokai. Referred from the pilot machine, we designed a demonstrator, called as JAWAS-N, for applying to non-destructive assay tools for uranium waste drums in JAEA Ningyo. In this paper, we present the modeling and the simulations concerning JAWAS-N's characteristics, and discuss for practical use compared analytical results with obtained some experimental data.

Development of high-grade VPS-tungsten coatings on F82H reduced activation steel

Tokunaga, Tomonori*; Watanabe, Hideo*; Yoshida, Naoaki*; Nagasaka, Takuya*; Kasada, Ryuta*; Lee, Y.-J.*; Kimura, Akihiko*; Tokitani, Masayuki*; Mitsuhara, Masatoshi*; Hinoki, Tatsuya*; et al.

Journal of Nuclear Materials, 442(1-3), p.S287 - S291, 2013/11

https://doi.org/10.1016/j.jnucmat.2012.11.004

Practical study for uranium measurement in uranium bearing wastes with the fast neutron direct interrogation method

Komeda, Masao; Ozu, Akira; Zaima, Naoki; Nakatsuka, Yoshiaki; Nakashima, Shinichi; Takase, Misao; Haruyama, Mitsuo; Kureta, Masatoshi

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-34-Kai Nenji Taikai Rombunshu (Internet), 9 Pages, 2013/10

no abstracts in English

The Concept of dose system for radiological protection

Hirayama, Hideo*; Nakashima, Hiroshi; Sanami, Toshiya*; Yamaguchi, Yasuhiro; Sato, Osamu*; Takagi, Shunji*; Suzuki, Toshikazu*; Iwai, Satoshi*

Nihon Genshiryoku Gakkai-Shi ATOMO, 55(2), p.83 - 96, 2013/02

Since the accident at the Fukushima Daiichi Power Plant, units of radiation doses such as Sv have been frequently reported by newspapers. However, it is not exactly understood even by experts on nuclear engineering that there are two different concepts which are the protection quantity such as the effective dose related to a radiation health risk and the practical quantity such as ambient dose equivalents related to measurements. In this special issue, Radiological Protection Quantity, and Operational Quantity and Radiological Protection Quantity, explain the radiation protection dose system including the protection and practical quantities established by ICRP and ICRU. Relation between Dosimeters used at Fukushima etc. and Radiological Protection Quantity describes a method and its problems to measure radiations from Cs on surface and underground using survey meters and personal dosimeters, and convert the measured values to effective doses.

Trial plan for advanced NDA system of uranium wastes; Introduction of active neutron method applied to NDA system

Zaima, Naoki; Nakashima, Shinichi; Nakatsuka, Yoshiaki; Kado, Kazumi; Haruyama, Mitsuo; Takase, Misao; Ozu, Akira; Kureta, Masatoshi

Kaku Busshitsu Kanri Gakkai (INMM) Nihon Shibu Dai-33-Kai Nenji Taikai Rombunshu (Internet), 8 Pages, 2012/10

We developed uranium mass assay systems for 200-litter wastes drums applied passive neutron measurements by NDA method and applied for the actual wastes drums stored in URCP. The neutron measurement methodology of U(,n) reaction using He proportional counters delivered superior performance, however also included some problems that the neutron penetration rates are depend upon matrices or density of wastes drums, so it was difficult to determine uranium mass against "unknown objects". For the purpose of solving problems active neutron measurements appears promising, we are now challenging to improve our equipments, which are composed of neutron generator, polyethylene moderators and He proportional counters. The uranium mass are determined by counting secondary neutrons generated from nuclear fissions. Our preliminary simulations suggest good performances with higher sensitivities and accuracies. It is extremely expected to contribute in the fields of safeguards works.

Conceptual design of multipurpose compact research reactor; Annual report FY2010 (Joint research)

Imaizumi, Tomomi; Miyauchi, Masaru; Ito, Masayasu; Watahiki, Shunsuke; Nagata, Hiroshi; Hanakawa, Hiroki; Naka, Michihiro; Kawamata, Kazuo; Yamaura, Takayuki; Ide, Hiroshi; et al.

JAEA-Technology 2011-031, 123 Pages, 2012/01

JAEA-Technology-2011-031.pdf:16.08MB

The number of research reactors in the world is decreasing because of their aging. However, the planning to introduce the nuclear power plants is increasing in Asian countries. In these Asian countries, the key issue is the human resource development for operation and management of nuclear power plants after constructed them, and also the necessity of research reactor, which is used for lifetime extension of LWRs, progress of the science and technology, expansion of industry use, human resources training and so on, is increasing. From above backgrounds, the Neutron Irradiation and Testing Reactor Center began to discuss basic concept of a multipurpose low-power research reactor for education and training, etc. This design study is expected to contribute not only to design tool improvement and human resources development in the Neutron Irradiation and Testing Reactor Center but also to maintain and upgrade the technology on research reactors in nuclear power-related companies. This report treats the activities of the working group from July 2010 to June 2011 on the multipurpose low-power research reactor in the Neutron Irradiation and Testing Reactor Center and nuclear power-related companies.