Insights from review and analysis of the Fukushima Dai-ichi accident

Hirano, Masashi; Yonomoto, Taisuke; Ishigaki, Masahiro; Watanabe, Norio; Maruyama, Yu; Shibamoto, Yasuteru; Watanabe, Tadashi; Moriyama, Kiyofumi

Journal of Nuclear Science and Technology, 49(1), p.1 - 17, 2012/01

https://doi.org/10.1080/18811248.2011.636538

An unprecedented earthquake and tsunami struck the Fukushima Dai-ichi Nuclear Power Plants on 11 March 2011. Although extensive efforts have been continuing on investigations into the causes and consequences of the accident, and the Japanese Government has presented a comprehensive report on the accident in the IAEA Ministerial Conference held in June 2011, there is still much to be clarified on what happened during the accident and why. This article aims at identifying what should be clarified further about the progression of the accident at Units 1-3 through the review and analysis of information released from Tokyo Electric Power Company and government authorities. It also discusses the safety issues raised by the accident based on the insights gained, in order to contribute to establishing a new framework that pursues continuous improvement toward the highest standards of safety that can reasonably be achieved.

Progress in development of the advanced Thomson scattering diagnostics

Hatae, Takaki; Howard, J.*; Ebizuka, Noboru*; Yoshida, Hidetsugu*; Nakatsuka, Masahiro*; Fujita, Hisanori*; Narihara, Kazumichi*; Yamada, Ichihiro*; Funaba, Hisamichi*; Hirano, Yoichi*; et al.

Journal of Physics; Conference Series, 227, p.012002_1 - 012002_6, 2010/06

https://doi.org/10.1088/1742-6596/227/1/012002

Antiferromagnetic bipolar semiconductor LaMnPO with ZrCuSiAs-type structure

Yanagi, Hiroshi*; Watanabe, Takumi*; Kodama, Katsuaki; Iikubo, Satoshi*; Shamoto, Shinichi; Kamiya, Toshio*; Hirano, Masahiro*; Hosono, Hideo*

Journal of Applied Physics, 105(9), p.093916_1 - 093916_8, 2009/05

https://doi.org/10.1063/1.3124582

Electronic and magnetic properties of a layered compound LaMnPO are examined in relation to a newly discovered iso-structural superconductor LaFeAs(P)O. Neutron diffraction measurements, together with temperature dependent magnetic susceptibility, clarify that LaMnPO is an antiferromagnet at least up to 375 K. The spin moment of a Mn ion is determined to be 2.26 at room temperature, and the spin configuration is antiparallel in the Mn-P plane and parallel to between the Mn-P planes, which is rather different from that of LaFeAsO. Optical absorption spectra, photoemission spectra, and temperature dependent electrical conductivity indicate that LaMnPO is a semiconductor. Furthermore, nominally undoped LaMnPO exhibits -type conduction while the conduction type is changed by doping of Cu or Ca to the La sites, indicating that LaMnPO is a bipolar conductor. Density functional calculation using the GGA+U approximation supports the above conclusions; the electronic band structure has an open band gap and the antiferromagnetic spin configuration is more stable than the ferromagnetic one.

Mizunami Underground Research Laboratory Project Plan for fiscal year 2008

Nishio, Kazuhisa; Oyama, Takuya; Mikake, Shinichiro; Mizuno, Takashi; Saegusa, Hiromitsu; Takeuchi, Ryuji; Amano, Kenji; Tsuruta, Tadahiko; Hama, Katsuhiro; Seno, Yasuhiro; et al.

JAEA-Review 2008-072, 28 Pages, 2009/02

JAEA-Review-2008-072.pdf:11.8MB

Japan Atomic Energy Agency (JAEA) at Tono Geoscience Center (TGC) is developing a geoscientific research project named the Mizunami Underground Research Laboratory (MIU) project in crystalline rock environment in order to establish scientific and technological basis for geological disposal of HLW. Geoscientific research at the MIU project is planned to be carried out in three phases over a period of 20 years; Surface-based Investigation Phase (Phase 1), Construction Phase (Phase 2) and Operation Phase (Phase 3). Currently, the project is under the Construction Phase. This document presents the following 2008 fiscal year plan based on the MIU Master Plan updated in 2002, (1) Investigation Plan, (2) Construction Plan, (3) Research Collaboration Plan, etc.

Development of a traveling wave resonant ring of the JNC high-power, high-duty electron linac

Nomura, Masahiro; Wang, Y. L.; Yamazaki, Yoshio; Hirano, Koichiro; Kato, Yuko*; Ishikawa, Takehiro*; Komata, Tomoki*; Hiyama, Toru*

Nuclear Instruments and Methods in Physics Research A, 463(1-2), p.42 - 49, 2001/05

https://doi.org/10.1016/S0168-9002(01)00229-7

None

Development of the high current electron accelerator

Nomura, Masahiro; Toyama, Shinichi; ; ; Yamazaki, Yoshio; Hirano, Koichiro; Omura, Akiko

JNC TN9410 2000-007, 376 Pages, 2000/03

JNC-TN9410-2000-007.pdf:15.51MB

According to the Long-Term Program for Partitioning and Transmutation which was published by the Atomic Energy Commission in 1988, study on the transmutation using an electron accelerator, which was a part of the program, has been carried out in the O-arai Engineering Center. It is the study on converting radioactive fission products for example Strontium and Cesium to stable nuclides by photonuclear reaction caused by high energy gamma-ray made by an electron accelerator. It was thought that a 100mA-100MeV (10MW output power) accelerator would be needed in order to carry out the transmutation study in engineering phase. Therefore, development of the High-Current Electron Accelerator whose target had been 20mA-10MeV (200 kW output power) accelerator was carried out as development of elemental technologies on beam stabilization. The conceptual design of the accelerator was started in 1989. In March 1997, the main facility of this accelerator was completed. The test operation was carried out to confiim the performance of the accelerator from January, 1999 to December. As the result, an output of about 14 kW was achieved. In addition, the electron beam of 40 kW could be to accelerate in short time. In this report, the design, fabrication and evalution of performance of the facilities are presented.

Development of accelerating unit for high beam current

; Toyama, Shinichi; Nomura, Masahiro; Hirano, Koichiro; Yamazaki, Yoshio; Sato, Isamu

JNC TN9400 99-073, 18 Pages, 1999/08

JNC-TN9400-99-073.pdf:0.57MB

A short traveling wave accelerator with a traveling wave resonant ring is proposed for high beam current accelerators (including the linear accelerator, circular accelerator and storage ring). It is a normal conducting accelerator. The CW beam current can be as high as 10A. Such kind of accelerator unit has large beam holes for damping all of the cavity high order modes in order to avoid the resonant buildup of the fields that would cause multibunch instabilities at high currents. It has high efficiency, high power input capability and low K. It is called "single mode" type. Even though beams are accelerated off the crest for phase stability in circular accelerator, the cavities do not need detuning.

The Development of RF cotrol system; Development of the interlock system

Hirano, Koichiro; Nomura, Masahiro; Yamazaki, Yoshio; *; *; *; *

JNC TN9400 99-040, 52 Pages, 1999/05

JNC-TN9400-99-040.pdf:2.7MB

The development of a high power CW electron linear accelerator was started in 1989 to study the feasibility of nuclear waste transmutation. The accelerator (10MeV, 100mA peak current, 4 ms pulse width, 50 Hz repetition) is dedicated machine for development of the high current acceleration technology in future need. It is necessary to develop the system which controls high power RF in order to stably accelerate the high current beam. Then, We have developed the interlock system for protecting accelerating tube from high current beam in time of trouble of high current beam and high power RF. We have succeeded in the development of the system so as to be able to choose interlock elements corresponding to the operating condition. Using the beam of the low electric power, the synthetic interlock system was tested. The beam was cut off at 3.5sec, after the interlock operated.

Injector commissioning of the PNC high power CW electron Linac

; ; Toyama, Shinichi; Nomura, Masahiro; ; Hirano, Koichiro

Journal of Pressure Vessel Technology, -(-), - Pages, 1998/00

None

Progress, status, and injector commissioning of the high power cw electron linac at PNC

Emoto, Takashi; Wang, Y.; Toyama, Shinichi; Nomura, Masahiro; Takei, Hayanori; Hirano, Koichiro; Yamazaki, Yoshio; Omura, Akiko; Tanimoto, Yasunori*; Tani, Satoshi

PNC TN9410 98-010, 51 Pages, 1997/12

PNC-TN9410-98-010.pdf:1.42MB

Design and construction of a high power CW (Continuous Wave) electron linac for studying feasibility of nuclear waste transmutation was started in l989 at PNC. The transmutation by photonuclear reaction using a electron accelerator has advantages of the small production for secondary radioactive waste and broad base of accelerator technology. The PNC accelerator (10 MeV, 20 mA average current, 20% duty) has been pre-commissioned. We have been very successful to produce 3 ms pulse width electron beam with 100 mA peak and energy about 2.9 MeV at present. The rest of the accelerating section was installed by March 1997. Studies are continued towards the designed goal of 100 mA beam with 4 msec pulse width and 50 Hz pulse repetition.