First demonstration experiment of the neutron rotation method for detecting nuclear material

Komeda, Masao; Toh, Yosuke; Tanabe, Kosuke*; Kitamura, Yasunori*; Misawa, Tsuyoshi*

Annals of Nuclear Energy, 159, p.108300_1 - 108300_8, 2021/09

https://doi.org/10.1016/j.anucene.2021.108300

Basic experiment for kinetics analysis in sub-critical sate

Kitano, Akihiro; Kishimoto, Yasufumi; Misawa, Tsuyoshi*; Hazama, Taira

KURRI Progress Report 2013, 1 Pages, 2014/10

http://www.rri.kyoto-u.ac.jp/PUB/report/PR/ProgRep2013/CO3.pdf#page=6

The approach to criticality is conventionally performed by the inverse multiplication method. The method uses neutron count rate at a steady state attained in a certain waiting time after a reactivity insertion; thus it requires long time (for example, several hours from the startup in Monju reactor). We have developed a more efficient method based on Critical Index (CI) featuring the time behavior of delayed neutrons.

Development of optical fiber detector for measurement of fast neutron

Yagi, Takahiro*; Misawa, Tsuyoshi*; Pyeon, C. H.*; Unesaki, Hironobu*; Shiroya, Seiji*; Kawaguchi, Shinichi*; Okajima, Shigeaki; Tani, Kazuhiro*

Proceedings of International Conference on the Physics of Reactors, Nuclear Power; A Sustainable Resource (PHYSOR 2008) (CD-ROM), 8 Pages, 2008/09

In order to insert a neutron detector in a narrow space such as a gap of between fuel plates and measure the fast neutrons in real time, a neutron detector with an optical fiber has been developed. This detector consists of an optical fiber whose tip is covered with mixture of neutron converter material and scintillator such as ZnS(Ag). The detector for fast neutrons uses ThO as converter material because Th makes fission reaction with fast neutrons. The place where Th can be uses is limited by regulations because Th is nuclear fuel material. The purpose of this research is to develop a new optical fiber detector to measure fast neutrons without Th and to investigate the characteristic of the detector. These detectors were used to measure a D-T neutron generator and fast neutron flux distribution at Fast Critical Assembly. The results showed that the fast neutron flux distribution of the new optical fiber detector with ZnS(Ag) was the same as it of the activation method, and the detector are effective for measurement of fast neutrons.

Development of design technology on thermal-hydraulic performance in tight-lattice rod bundle, 3; Numerical estimation on rod bowing effect based on X-ray CT data

Misawa, Takeharu; Onuki, Akira; Mitsutake, Toru*; Katsuyama, Kozo; Misawa, Susumu*; Nagamine, Tsuyoshi; Nakamura, Yasuo; Akimoto, Hajime

Proceedings of 15th International Conference on Nuclear Engineering (ICONE-15) (CD-ROM), 8 Pages, 2007/04

Rod displacement measurements by X-ray CT and its impact on thermal-hydraulics in tight-lattice rod bundle (Joint research)

Mitsutake, Toru*; Katsuyama, Kozo*; Misawa, Takeharu; Nagamine, Tsuyoshi*; Kureta, Masatoshi*; Matsumoto, Shinichiro*; Akimoto, Hajime

JAERI-Tech 2005-034, 55 Pages, 2005/06

JAERI-Tech-2005-034.pdf:7.76MB

In tight-lattice bundles with about 1mm gap between rods, a rod displacement might affect thermal-hydraulic characteristics. The inside-structure observation of the simulated seven-rod bundle of RMWR was made with the high-energy X-ray CT of JNC. The CT view assured that the rod position was almost the same as expected by design. In the heat transfer experiments, all thermocouples on the center rod showed almost simultaneous BT-induced temperature increase and on the same axial heights showed quite similar time-variation behaviors in the vapor cooling heat transfer regime. It showed that the effect of the geometrical asymmetry was small on the BT characteristics. The calculated critical power by subchannel analysis with the input of the CT measured rod position was smaller by about 5% than that with the designed rod position. It concluded that the error in the calculated critical power was attributable not to the asymmetry in the rod position, but to the models in the subchannel analysis code.

Experimental study on accelerator driven subcritical reactor, JAERI's nuclear research promotion program, H12-031 (Contract research)

Shiroya, Seiji*; Misawa, Tsuyoshi*; Unesaki, Hironobu*; Ichihara, Chihiro*; Kobayashi, Keiji*; Nakamura, Hiroshi*; Shin, Kazuo*; Imanishi, Nobutsugu*; Kanazawa, Satoshi*; Mori, Takamasa

JAERI-Tech 2004-025, 93 Pages, 2004/03

JAERI-Tech-2004-025.pdf:6.69MB

In view of the future plan of Research Reactor Institute, Kyoto University, the present study consisted of (1) the transmission experiments of high energy neutrons through materials, (2) experimental simulation of ADSR using the Kyoto University Critical Assembly(KUCA), and (3) conceptual neutronics design study on KUR type ADSR using the MCNP-X code. Through the present study, valuable knowledge on the basic nuclear characteristics of ADSR, which is indispensable to promote the study on ADSR, was obtained both theoretically and experimentally. For the realization of ADSR, it is considered to be necessary to accumulate results of research steadily. For this purpose, it is inevitable (1) to compile the more precise nuclear data for the wide energy range, (2) to establish experimental techniques for reactor physics study on ADSR including subcriticality measurement and absolute neutron flux measurement, and (3) to develop neutronics calculation tools which take into account the neutron generation process by the spallation reaction and the delayed neutron behavior.

Development of design technology on thermal-hydraulic performance in tight-lattice rod bundles, 2; Measurement of rod-bowing effect test assembly by X-ray CT technique

Katsuyama, Kozo; Misawa, Susumu*; Mitsutake, Toru*; Misawa, Takeharu; Nagamine, Tsuyoshi; Nakamura, Yasuo; Onuki, Akira; Akimoto, Hajime

no journal, , 

no abstracts in English

Prototype FBR Monju system start up test "zero power reactor physics test", 5; Applicability of sub-criticality measurement methods

Kitano, Akihiro; Mori, Tetsuya; Nagata, Akito*; Saito, Kosuke; Misawa, Tsuyoshi*; Tamagawa, Yoichi*

no journal, , 

no abstracts in English

Accelerator neutron dosimetry using composite-gas-filled proportional counting tube

Usui, Toshihide; Mikami, Satoshi; Nakayama, Naoto; Hashimoto, Makoto; Suzuki, Chihiro*; Yamasaki, Keizo*; Misawa, Tsuyoshi*

no journal, , 

no abstracts in English

Reactivity estimation of KUCA subcritical cores, 2; Estimation based on power profile in quasi-steady state

Yamane, Yuichi; Araki, Shohei; Kitamura, Yasunori*; Misawa, Tsuyoshi*

no journal, , 

A new reactivity estimation method has been developed based on the power profile in quasi-steady state. Several subcritical cores were set up in KUCA A-core and neutron count rate was measured to apply estimation methods for comparison. The values obtained by new method, E, in an near-critical core and calculated value by using MVP code, C, show C/E in the range between 0.9 and 1.5.