Feasibility study of PGAA for boride identification in simulated melted core materials

Tsuchikawa, Yusuke; Abe, Yuta; Oishi, Yuji*; Kai, Tetsuya; Toh, Yosuke; Segawa, Mariko; Maeda, Makoto; Kimura, Atsushi; Nakamura, Shoji; Harada, Masahide; et al.

JPS Conference Proceedings (Internet), 33, p.011074_1 - 011074_6, 2021/03

https://doi.org/10.7566/JPSCP.33.011074

In the decommissioning of the Fukushima-Daiichi (1F) Nuclear Power Plant, it is essential to understand characteristics of the melted core materials. The estimation of boride in the real debris is of great importance to develop safe debris removal plans. Hence, it is required to investigate the amount of boron in the melted core materials with nondestructive methods. Prompt gamma-ray activation analysis (PGAA) is one of the useful techniques to determine the amount of borides by means of the 478 keV prompt gamma-ray from neutron absorption reaction of boron. Moreover, it is well known that the width of the 478 keV gamma-ray peak is typically broadened due to the Doppler effect. The degree of the broadening is affected by coexisting materials, and can be recognized by the width of the prompt gamma-ray peak. As a feasibility study, the prompt gamma-ray from boride samples were measured using the ANNRI, NOBORU, and RADEN beamlines at the Materials and Life Science Experimental Facility (MLF) of Japan Proton Accelerator Complex (J-PARC).

Study on magnetic property change on neutron irradiated austenitic stainless steel

Nemoto, Yoshiyuki; Oishi, Makoto; Ito, Masayasu; Kaji, Yoshiyuki

Nihon Hozen Gakkai Dai-12-Kai Gakujutsu Koenkai Yoshishu, p.105 - 112, 2015/07

Authors previously reported that Eddy current method and AC magnetization method have potential to be applied for development of diagnostic technics to detect the sign of material degradation before cracking on the austenitic stainless steels used as structural material in nuclear power plants. In typical austenitic stainless steels such as type304, magnetic ferrite phase would exist in the alloy before irradiation, and it is concerned to disturb the magnetic measurement on irradiated material. Magnetic measurements were conducted in this work on type304 austenitic stainless steel specimens irradiated up to different doses. In addition, microstructure observation was conducted on the area including grain boundary to discuss the correlation of magnetization on irradiated austenitic stainless alloy and grain boundary cracking. Obtained magnetic data on irradiated type304 stainless steel were seen clearly different from that on un-irradiated specimen, and showed positive correlation with radiation dose, therefore it was thought that magnetic measurement technics can be applied for the material which contains certain quantity of ferrite phase before irradiation. In the microstructural observation, magnetic phase (FeNi) formation along the grain boundary was revealed.

Structural and valence changes of europium hydride induced by application of high-pressure H

Matsuoka, Takahiro*; Fujihisa, Hiroshi*; Hirao, Naohisa*; Oishi, Yasuo*; Mitsui, Takaya; Masuda, Ryo; Seto, Makoto*; Yoda, Yoshitaka*; Shimizu, Katsuya*; Machida, Akihiko; et al.

Physical Review Letters, 107(2), p.025501_1 - 025501_4, 2011/07

https://doi.org/10.1103/PhysRevLett.107.025501

Europium-hydride EuH exposed to high-pressure H conditions has been found to exhibit structural and valence changes, (=2, divalent) 63/ (=2, 7.2-8.7 GPa) 4/ (2, 8.7-9.7 GPa) 4/ (2, 9.7 GPa-, trivalent). Having trivalent character and distorted cubic fcc structure, the 4/ structure is the -phase which has been commonly observed for other rare-earth metal hydrides. Our study clearly demonstrates that EuH is no longer an "irregular" member of the rare earth metal hydrides.

Ultrahigh-pressure measurement in the multimegabar range by energy-domain synchrotron radiation Fe-Mssbauer spectroscopy using focused X-rays

Mitsui, Takaya; Seto, Makoto; Hirao, Naohisa*; Oishi, Yasuo*; Kobayashi, Yasuhiro*; Higashitaniguchi, Satoshi*; Masuda, Ryo*

Japanese Journal of Applied Physics, Part 2, 46(16), p.L382 - L384, 2007/04

https://doi.org/10.1143/JJAP.46.L382

Energy-domain synchrotron radiation Mssbauer spectroscopy was performed by a single-line Mssbauer filtering technique and focusing X-ray optics. Pure nuclear Bragg reflection from a heated FeBO single crystal was used for a neV order bandwidth ultrahigh energy resolution X-ray analyzer. As an example of small target research, the Mssbauer transmission spectrum of polycrystalline iron metal was observed using a diamond anvil cell at multimegabar pressures (252 GPa) for the first time.

Intense femto-second laser-driven X-ray source coupled with multiple directional quantum beams for applications

Daido, Hiroyuki; Sagisaka, Akito; Ogura, Koichi; Orimo, Satoshi; Nishiuchi, Mamiko; Yogo, Akifumi; Mori, Michiaki; Li, Z.*; Kiriyama, Hiromitsu; Kanazawa, Shuhei; et al.

X-Ray Lasers 2006; Springer Proceedings in Physics, Vol.115, p.595 - 605, 2007/00

At present, using ultra-short high intensity lasers at APRC, JAEA Kansai photon research institute, we are developing laser driven multiple quantum beams such as protons, X-rays, electrons and THz waves. These beams are perfectly synchronized with each other. The pulse duration of each beam is lass than a pico-second. They have sharp directionality with high brightness. If we properly combined these, we have new pump-probe techniques for various applications.

Development of elemental components in NDA systems for certifying radioactive wastes with the clearance level

Tsutsumi, Masahiro; Oishi, Tetsuya*; Yamasoto, Kotaro; Yoshida, Makoto

JAERI-Research 2004-021, 43 Pages, 2004/12

JAERI-Research-2004-021.pdf:8.55MB

We have designed and developed a measurement system to certify radioactive wastes below the clearance level. By advancing non-destructive -ray assay technology, it aims at quantitative determination of radionuclides contained in 200 litter drum/container wastes. Unlike the waste from a nuclear power plant, you have to assume that the waste originating from radioisotope usage and nuclear research laboratory have a variety of contents and a complex mixture of radionuclides, and furthermore the uniformity of activity concentration is unknown. To cope with the problems, we have developed the -ray measuring instruments (units) with effective improvement of capability against each problem. They are (1) germanium spectrometry unit for enhanced peak identification, (2) positioning detection unit for positioning of interactions and (3)high-efficiency detection unit for separation of low-energy component. This report summarizes the direction of the clearance level measuring system and the three developed measuring units with their performances.

An EGS4 user code developed for design and optimization of -ray detection systems

Oishi, Tetsuya; Tsutsumi, Masahiro; Sugita, Takeshi*; Yoshida, Makoto

Journal of Nuclear Science and Technology, 40(6), p.441 - 445, 2003/06

https://doi.org/10.3327/jnst.40.441

An EGS4 user code has been developed to design and optimize ray detection systems for several types of radiation sources. The code is fundamentally based on the PRESTA-CG, which is improved on the electron transport in the EGS4 and specialized for the utilization of a combinatorial geometry (CG) method. The main additional functions in the present user code are classified into two parts of the definition of radiation sources and the transport of photons. The developed user code was applied to two types of detection systems in order to demonstrate its availability. As the result, it was found that the present code allows the detailed response analysis of complicated detection systems for several sources with just a simple handling.

Design of an anti-compton spectrometer for low-level radioactive wastes using Monte Carlo techniques

Tsutsumi, Masahiro; Oishi, Tetsuya; Kinouchi, Nobuyuki; Sakamoto, Ryuichi; Yoshida, Makoto

Journal of Nuclear Science and Technology, 39(9), p.957 - 963, 2002/09

https://doi.org/10.3327/jnst.39.957

An anti-Compton spectrometer with semi-2 Compton suppression is designed to identify the photons emitted from low-level radioactive wastes from radioisotope usage and nuclear research laboratory. Since the objective sample is massive and large, the system has a full opening towards the sample position. The characteristics and features of the system concerning Compton suppression and reduction of the background component due to natural radioactive source are estimated by the Monte Carlo simulations. The anti-Compton technique is shown to be quite advantageous for the reduction of the surrounding natural background radiation, as well as the suppression of the background for the higher energy photons.

Development of a plutonium air monitor for emergency environmental monitoring

Kinouchi, Nobuyuki; Oishi, Tetsuya; Noguchi, Hiroshi; Yoshida, Makoto; Kato, Shohei; Ito, Katsuhito*

Radioisotopes, 51(2), p.71 - 77, 2002/02

https://doi.org/10.3769/radioisotopes.51.71

We have developed an air monitor which is possible to measure rapidly and sensitively the concentration of plutonium for the environmental monitoring at an accident of a nuclear reprocessing plant. The monitor is designed to collect airborne plutonium by drawing the ambient air through a filter and to detect the activity by alpha spectroscopy. The following two methods are equipped with the monitor: continuous measurement at atomospheric pressure and batch measurement at vacuum. The description of the air monitor and the results of performance test are reported.

Response analysis of radioactive gas monitors for short duration inflow of radioactive gas

Oishi, Tetsuya; Yoshida, Makoto

Journal of Nuclear Science and Technology, 38(12), p.1115 - 1119, 2001/12

https://doi.org/10.3327/jnst.38.1115

no abstracts in English