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Featured researches published by Hiroshi Okashita.


Journal of Nuclear Science and Technology | 1975

Non-Destructive Gamma-Ray Spectrometry on Spent Fuels of a Boiling Water Reactor

Shojiro Matsuura; Harumichi Tsuruta; Takenori Suzaki; Hiroshi Okashita; Hirokazu Umezawa; Haruo Natsume

The spent fuels from the JPDR-I reactor were measured by means of a γ-scanning facility installed in the fuel storage pool. The spatial distributions of the fission products (134Cs and 137Cs) were measured and analyzed in reference to the effects of control rod pattern. The ratios holding between the products of neutron capture and of direct fission (134Cs/137Cs and 154Eu/137Cs) were also examined for its relevance to non-destructive burnup determination. The activity ratios of the fission products can be expressed by a linear function of burnup, provided that corrections are made to account for differences in irradiation history and for spatial variations in the neutron spectrum.


Journal of Nuclear Science and Technology | 1971

Fast Computer Analysis of the γ Spectrum from Ge(Li) Detectors

Hiroshi Baba; Hiroshi Okashita; S. Baba; Toshio Suzuki; Hirokazu Umezawa; Haruo Natsume

A method for rapidly analyzing the γ spectrum obtained with Ge(Li) detectors was developed for a medium-size electronic computer. The analysis is based on the first derivative method, associated with a number of peak-shape tests. The effects of data smoothing and of changes in peak width were studied to determine the optimum conditions for spectrum analysis. The resulting computer program was subjected to various quality tests on the predicted values of the peak position and area. The results of the tests showed that the code thus developed works quite satisfactorily. The code requires 10 sec and a memory core of 29 k when using a FACOM 230–60 for the analysis of a 2,047 channel spectrum.


Archive | 1985

Synthesis of Transuranium Nuclides from Interaction of 160 with 238U

N. Shinohara; S. Ichikawa; Shigekazu Usuda; Toshio Suzuki; Hiroshi Okashita; T. Sekine; K. Hata; T. Horiguchi; Y. Yoshizawa; S. Shibata; I. Fujiwara

Many studies of actinides, especially of transuranium elements, have been performed mainly owing to scientists’ endeavors to discover new elements and nuclides. (1) In spite of these efforts, the mechanism of the formation of transuranium nuclides by heavy-ion bombardment and the nuclear and chemical properties of the synthesized actinide nuclides have not been clearly elucidated, and a great deal remains to be examined in more detail. In this context, we have begun the investigation of heavy-ion nuclear reactions(2): A system in which a uranium target is irradiated by oxygen ions (160 + 238U), was chosen. For this reaction seventeen nuclides (250Fm) 244,245,248Cf, 242Cm, 233,239Np) 237,239U 225,226,227,228Th, 224,225Ac, and 223,224Ra) were identified and the condition of formation for these nuclides was clarified. This paper deals with a novel method of mutual rapid separation of the synthesized transuranium elements by ion exchange and a discussion of the mechanism which governs the heavy-ion nuclear reactions.


Journal of Nuclear Science and Technology | 1977

Gamma-Ray Spectrometry and Chemical Analysis Data of JPDR-I Spent Fuel

Haruo Natsume; Hiroshi Okashita; Hirokazu Umezawa; Shuji Okazaki; Toshio Suzuki; Mamoru Ohnuki; Tamotsu Sonobe; Yoshinori Nakahara; Shin-Ichi Ichikawa; Shigekazu Usuda; Shojiro Matsuura; Harumichi Tsuruta; Takenori Suzaki; Takuji Komori; Shuzo Tamura; Katsufumi Gunji; Kimiko Tamura


Journal of Nuclear Science and Technology | 1986

Non-Destructive and Destructive Measurements on Burnup Characteristics of Japan Power Demonstration Reactor-I Full-Core Fuel Assemblies

Takenori Suzaki; Shuji Okazaki; Hiroshi Okashita; Iwao Kobayashi; Toshio Suzuki; Nobuaki Kohno; Mamoru Ohnuki; N. Shinohara; Tamotsu Sonobe; Akio Ohno; Kiyonobu Murakami; Hirokazu Umezawa; Harumichi Tsuruta; Shojiro Matsuura; Yoshiro Asakura; Sadao Araya; Tanehiko Yamanouchi


Journal of Nuclear Science and Technology | 1973

Correlation of Amounts of Transplutonium Nuclides with Burnup in the JPDR-I Spent Fuel

Hirokazu Umezawa; Shin-Ichi Ichikawa; Toshio Suzuki; Hiroshi Okashita; Haruo Natsume


Journal of Nuclear Science and Technology | 1972

A Comparison of Radiochemical Methods for Cesium-137 Determination

Hiroshi Okashita; Haruo Natsume


Physical Review C | 1986

Actinides produced by C12 + Pu242 and O16 + U238 reactions

Nobuo Shinohara; Shigekazu Usuda; S. Ichikawa; Tohru Suzuki; Masaaki Magara; Hiroshi Okashita; Hiroo Yoshikawa; T. Horiguchi; Y. Iwata; S. Shibata; Ichiro Fujiwara


Journal of the Atomic Energy Society of Japan / Atomic Energy Society of Japan | 1973

Development of burnup determination technique by destructive measurement

Haruo Natsume; Hiroshi Okashita; Hirokazu Umezawa


Archive | 1970

METHOD FOR PRODUCING RADIOACTIVE TELLURIUM

Hirokazu Umezawa; Hiroshi Okashita

Collaboration


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Hirokazu Umezawa

Japan Atomic Energy Research Institute

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Haruo Natsume

Japan Atomic Energy Research Institute

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Toshio Suzuki

Japan Atomic Energy Research Institute

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Harumichi Tsuruta

Japan Atomic Energy Research Institute

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Shigekazu Usuda

Japan Atomic Energy Research Institute

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Shojiro Matsuura

Japan Atomic Energy Research Institute

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Takenori Suzaki

Japan Atomic Energy Research Institute

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Mamoru Ohnuki

Japan Atomic Energy Research Institute

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N. Shinohara

Japan Atomic Energy Research Institute

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S. Ichikawa

Japan Atomic Energy Research Institute

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