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Journal Articles

Mesospheric ionization during substorm growth phase

Murase, Kiyoka*; Kataoka, Ryuho*; Nishiyama, Takanori*; Nishimura, Koji*; Hashimoto, Taishi*; Tanaka, Yoshimasa*; Kadokura, Akira*; Tomikawa, Yoshihiro*; Tsutsumi, Masaki*; Ogawa, Yasunobu*; et al.

Journal of Space Weather and Space Climate (Internet), 12, p.18_1 - 18_16, 2022/06

 Times Cited Count:0 Percentile:24.42(Astronomy & Astrophysics)

We identified two energetic electron precipitation (EEP) events during the growth phase of moderate substorms and estimated the mesospheric ionization rate for an EEP event for which the most comprehensive dataset from ground-based and space-born instruments was available. The mesospheric ionization signature reached below 70 km altitude and continued for ~15 min until the substorm onset, as observed by the PANSY radar and imaging riometer at Syowa Station in the Antarctic region. We also used energetic electron flux observed by the Arase and POES 15 satellites as the input for the air-shower simulation code PHITS to quantitatively estimate the mesospheric ionization rate. Combining the cutting-edge observations and simulations, we shed new light on the space weather impact of the EEP events during geomagnetically quiet times, which is important to understand the possible link between the space environment and climate.

Journal Articles

Benchmark critical experiments and FP worth evaluation for a heterogeneous system of uranium fuel rods and uranium solution poisoned with pseudo-fission-product elements

Tonoike, Kotaro; Yamamoto, Toshihiro; Miyoshi, Yoshinori; Uchiyama, Gunzo; Watanabe, Shoichi*

Journal of Nuclear Science and Technology, 46(4), p.354 - 365, 2009/04

 Times Cited Count:1 Percentile:10.23(Nuclear Science & Technology)

A series of critical experiments were performed using heterogeneous cores at the Static Experiment Critical Facility in Japan Atomic Energy Agency in order to obtain systematic benchmark data concerning dissolving process in a reprocessing plant. Focusing on the introduction of the burn-up credit, critical mass measurement was conducted for a combination of uranium dioxide fuel rods (5wt% $$^{235}$$U) and uranyl nitrate solution (6wt% $$^{235}$$U) poisoned with pseudo fission product (FP) elements - samarium, cesium, rhodium, and europium. Fuel rods were arrayed with an 1.5-cm lattice interval in the poisoned fuel solution in a 60-cm diameter cylindrical tank. The uranium concentrations of the solution was roughly kept at about 320gU/L, and the FP element concentrations were adjusted to be equivalent to a burn-up of about 30GWd/t. The result provides basic experimental data for validation of computational methods to evaluate a reactivity effect of each FP element, as well as benchmark criticality data for validation of neutron multiplication factor calculation of heterogeneous systems of spent fuel. In the report, detail of the experiments and its benchmark models will be presented as well as the procedure and the result of separate reactivity worth evaluation for each FP element. The experimental result and the computational evaluation will also be compared.

Journal Articles

Benchmark critical experiments and FP worth evaluation for a heterogeneous system of uranium fuel rods and pseudo FP doped uranium solution

Tonoike, Kotaro; Miyoshi, Yoshinori; Uchiyama, Gunzo; Watanabe, Shoichi*; Yamamoto, Toshihiro*

Proceedings of 8th International Conference on Nuclear Criticality Safety (ICNC 2007), p.222 - 227, 2007/05

In order to obtain systematic benchmark criticality data concerning dissolving process in a reprocessing plant for LWR spent fuel, a series of critical experiments were performed using heterogeneous cores at the Static Experiment Critical Facility (STACY) in Japan Atomic Energy Agency (JAEA). Focusing on the introduction of the burn-up credit to the process, critical mass measurement was conducted for a combination of uranium fuel rods and uranium solution where pseudo fission product (FP) materials were doped. In this report, the "pseudo FP materials" means elements such as Sm, Cs, Rh and Eu whose isotopic composition is natural but which contains some FP nuclide(s). The result is going to provide basic experimental data for validation of computational methods to evaluate a reactivity effect of each FP material, as well as benchmark criticality data for validation of neutron multiplication factor calculation of heterogeneous systems of spent fuel. In the report, detail of the experiments including a differential reactivity worth curve over the solution level variation is going to be provided as well as the procedure and the result of separate reactivity worth evaluation of each pseudo FP material. Comparison of the experimental result and the computational evaluation will also be presented.

Journal Articles

Nuclear criticality safety aspects of "specified"-uranium fuel cycle facilities

Okuno, Hiroshi; Suyama, Kenya; Takahashi, Satoshi*; Watanabe, Shoichi*; Tonoike, Kotaro; Miyoshi, Yoshinori

Transactions of the American Nuclear Society, 95(1), p.283 - 284, 2006/11

no abstracts in English

Journal Articles

Simultaneous measurements of ion and electron currents using a novel compact electrostatic end-loss-current detector

Hirata, Mafumi*; Miyake, Yasuhiro*; Chujo, T.*; Kohagura, Junko*; Numakura, Tomoharu*; Shimizu, Kiyoaki*; Ito, Marie*; Kiminami, Serina*; Morimoto, Naomichi*; Hirai, Katsuaki*; et al.

Review of Scientific Instruments, 77(10), p.10E719_1 - 10E719_3, 2006/10

 Times Cited Count:0 Percentile:0.01(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Neutrino signals from the formation of a black hole; A Probe of the equation of state of dense matter

Sumiyoshi, Kosuke*; Yamada, Shoichi*; Suzuki, Hideyuki*; Chiba, Satoshi

Physical Review Letters, 97(9), p.091101_1 - 091101_4, 2006/09

 Times Cited Count:101 Percentile:93.09(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Postbounce evolution of core-collapse supernovae; Long-term effects of the equation of state

Sumiyoshi, Kosuke*; Yamada, Shoichi*; Suzuki, Hideyuki*; Shen, H.*; Chiba, Satoshi; Toki, Hiroshi*

Astrophysical Journal, 629(2, Part1), p.922 - 932, 2005/08

 Times Cited Count:226 Percentile:97.41(Astronomy & Astrophysics)

no abstracts in English

Journal Articles

Measurement of temperature effect on low enrichment STACY heterogeneous core

Watanabe, Shoichi; Yamamoto, Toshihiro; Miyoshi, Yoshinori

Transactions of the American Nuclear Society, 91, p.431 - 432, 2004/11

Temperature effect is a main factor which affects the transient characteristics at a criticality accident. A series of reactivity effects due to changes in fuel temperatures were measured for two kinds of STACY heterogeneous lattice configurations. The core was composed of LWR-type fuel rod array and low-enriched uranyl-nitrate-solution concerning the dissolver of the reprocessing facility for LWR spent fuel. The critical solution heights at various solution temperatures were measured. From the change of the critical water height with fuel temperature, the reactivity effect was evaluated by a critical-solution-level worth method. The temperature effect was also calculated by using SRAC and the transport calculation code TWODANT. The experimental value was estimated to be -2.0 cent/$$^{circ}$$C for the case "2.1cm-pitch", and -2.5 cent/$$^{circ}$$C for the case "1.5cm-pitch". The calculated results gave agreement with the experiments within $$sim$$10%.

Journal Articles

Real time $$alpha$$ value measurement with Feynman-$$alpha$$ method utilizing time series data acquisition on low enriched uranium system

Tonoike, Kotaro; Yamamoto, Toshihiro; Watanabe, Shoichi; Miyoshi, Yoshinori

Journal of Nuclear Science and Technology, 41(2), p.177 - 182, 2004/02

 Times Cited Count:14 Percentile:66.17(Nuclear Science & Technology)

As a part of the development of a subcriticality monitoring system, a system which has a time series data acquisition function of detector signals and a real time evaluation function of alpha value with the Feynman-$$alpha$$ method was established, with which the kinetic parameter (alpha value) was measured at the STACY heterogeneous core. The Hashimoto's difference filter was implemented in the system, which enables the measurement at a critical condition. The measurement result of the new system agreed with the pulsed neutron method.

JAEA Reports

Development of a kinetics analysis code for fuel solution combined with thermal-hydraulics analysis code PHOENICS and analysis of natural-cooling characteristic test of TRACY (Contract research)

Watanabe, Shoichi; Yamane, Yuichi; Miyoshi, Yoshinori

JAERI-Tech 2003-045, 73 Pages, 2003/03

JAERI-Tech-2003-045.pdf:4.96MB

Since exact information is not always acquired in the criticality accident of fuel-solution, parametric survey calculations are required for grasping behaviors of the thermal-hydraulics. On the other hand, the practical methods of the calculation which can reduce the computation time with allowable accuracy will be also required, since the conventional method takes a long calculation time. In order to fulfill the requirement, a three-dimensional nuclear-kinetics analysis code considering thermal-hydraulic based on the multi-region kinetic equations with one-group neutron energy was created by incorporating the thermal-hydraulics analysis code PHOENICS as a subroutine. The computation time of the code was shortened by separating time mesh intervals of the nuclear- and heat-calculations from that of the hydraulics calculation, and by regulating automatically the time mesh intervals in proportion to power change rate. A series of analysis were performed for the natural-cooling characteristic test using TRACY in which the power changed slowly for 5 hours after the transient power resulting from the reactivity insertion of a 0.5 dollar. It was found that the code system was able to calculate within the limit of practical time, and acquired the prospect of reproducing the experimental values considerably for the power and temperature change.

Journal Articles

Critical experiments on 10% enriched uranyl nitrate solution using an 80-cm-diameter cylindrical core

Yamane, Yuichi; Miyoshi, Yoshinori; Watanabe, Shoichi; Yamamoto, Toshihiro

Nuclear Technology, 141(3), p.221 - 232, 2003/03

 Times Cited Count:4 Percentile:31.71(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Criticality safety benchmark experiment on 10% enriched uranyl nitrate solution using a 28-cm-thickness slab core

Yamamoto, Toshihiro; Miyoshi, Yoshinori; Kikuchi, Tsukasa*; Watanabe, Shoichi

Journal of Nuclear Science and Technology, 39(7), p.789 - 799, 2002/07

 Times Cited Count:5 Percentile:34.65(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Simulation tests for thermal characteristics of JCO precipitation vessel using a mock-up device

Watanabe, Shoichi; Miyoshi, Yoshinori; Yamane, Yuichi

JAERI-Tech 2002-043, 93 Pages, 2002/03

JAERI-Tech-2002-043.pdf:6.74MB

no abstracts in English

JAEA Reports

A Solution pouring test of JCO precipitation tank using a visualization vessel

Watanabe, Shoichi; Miyoshi, Yoshinori

JAERI-Data/Code 2001-008, 62 Pages, 2001/03

JAERI-Data-Code-2001-008.pdf:17.38MB

no abstracts in English

Journal Articles

Present status of nuclear criticality safety research; highlights of International Conference on Nuclear Criticality Safety(ICNC-91)

Nishina, Kojiro*; Yamane, Yoshihiro*; Kobayashi, Iwao; Tachimori, Shoichi; ; Miyoshi, Yoshinori; Okuno, Hiroshi; Nakajima, Ken; Mitake, Susumu*; *; et al.

Nihon Genshiryoku Gakkai-Shi, 34(4), p.311 - 319, 1992/04

 Times Cited Count:0 Percentile:0.49(Nuclear Science & Technology)

no abstracts in English

JAEA Reports

Effect of nonuniform concentration profile of plutonium in mixer settler on criticality of the Purex process

; Miyoshi, Yoshinori; Tachimori, Shoichi

JAERI-M 91-184, 31 Pages, 1991/11

JAERI-M-91-184.pdf:0.94MB

no abstracts in English

Journal Articles

Nuclear criticality safety design of STACY and TRACY; Two criticality experiments facilities

Yanagisawa, Hiroshi; Takeshita, Isao; Miyoshi, Yoshinori; Sugikawa, Susumu; Suzaki, Takenori; Tachimori, Shoichi

Proc. of the 91 Int. Conf. on Nuclear Criticality Safety,Vol. 2, p.V-65 - V-72, 1991/00

no abstracts in English

Journal Articles

Proceedings of the 2nd KURRI symposium on criticality safety

Tachimori, Shoichi; Miyoshi, Yoshinori

KURRI-TR-294, p.62 - 68, 1987/00

no abstracts in English

Oral presentation

Function test and critical experiment on uranyl nitrate solution with STACY, 34; Reactivity effect of FP material on heterogeneous core with 1.5 cm lattice pitch

Watanabe, Shoichi; Tonoike, Kotaro; Yoshiyama, Hiroshi; Yamamoto, Toshihiro; Izawa, Kazuhiko; Miyoshi, Yoshinori

no journal, , 

no abstracts in English

19 (Records 1-19 displayed on this page)
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