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Kobayashi, Jun; Aizawa, Kosuke; Ezure, Toshiki; Nagasawa, Kazuyoshi*; Kurihara, Akikazu; Tanaka, Masaaki
JAEA-Research 2022-009, 125 Pages, 2023/01
JAEA-Research-2022-009.pdf:29.22MB
The design studies of an advanced loop-type sodium-cooled fast reactor (Advanced- SFR) have been carried out by the Japan Atomic Energy Agency (JAEA). At the core outlet, temperature fluctuations occur due to mixing of hot sodium from the fuel assembly with cold sodium from the control rod channels and radial blanket assembly. These temperature fluctuations may cause high cycle thermal fatigue around a bottom of Upper Internal Structure (UIS) located above the core. Therefore, we conducted a water experiment using a 1/3 scale 60 degree sector model that simulated the upper plenum of the advanced loop-type sodium-cooled reactor. And we proposed some countermeasures against large temperature fluctuations that occur at the bottom of the UIS. In this report, we have summarized that the effect of the countermeasure structure to mitigate the temperature fluctuation generated at the bottom of UIS is confirmed, and the Reynolds number dependency of the countermeasure structure and the characteristics of the temperature fluctuation on the control rod surface.
Kobayashi, Jun; Aizawa, Kosuke; Ezure, Toshiki; Kurihara, Akikazu; Tanaka, Masaaki
Hozengaku, 20(3), p.89 - 96, 2021/10
Hot sodium from the fuel assembly can mix with cold sodium from the control rod (CR) channel and the blanket assemblies at the bottom plate of the Upper Internal Structure (UIS) of Advanced-SFR. Temperature fluctuation due to mixing of the fluids at different temperature between the core outlet and cold channel may cause high cycle thermal fatigue on the structure around the bottom of UIS. A water experiment using a 1/3 scale 60 degree sector model simulating the upper plenum of the Advanced-SFR has been conducted to examine countermeasures for the significant temperature fluctuation generated around the bottom of UIS. We focused on the temperature fluctuations near the primary and backup control rod channels, and studied the countermeasure structure to mitigate the temperature fluctuation through temperature distribution and flow velocity distribution measurements. As a result, effectiveness of the countermeasure to mitigate the temperature fluctuation intensity was confirmed.
Kobayashi, Jun; Aizawa, Kosuke; Ezure, Toshiki; Kurihara, Akikazu; Tanaka, Masaaki
Hozengaku, 20(3), p.97 - 101, 2021/10
Focusing on the thermal striping phenomena that occurs at a bottom of the internal structure of an advanced sodium-cooled fast reactor (Advanced-SFR) that has been designed by the Japan Atomic Energy Agency, a water experiment using a 1/3 scale 60 degree sector model simulating the upper plenum of the Advanced-SFR has been conducted to examine countermeasures for the significant temperature fluctuation generated around the bottom of Upper Internal Structure (UIS). In the previous paper, we reported the effect of measures to mitigate temperature fluctuations around the control rod channels. In this paper, the same test section was used, and a water experiment was conducted to obtain the characteristics of temperature fluctuations around the radial blanket fuel assembly. And the shape of the Core Instrumentation Support Plate (CIP) was modified, and it was confirmed that it was highly effective in alleviating temperature fluctuations around the radial blanket fuel assembly.
Yoshimoto, Masahiro; Nakanoya, Takamitsu; Yamazaki, Yoshio; Saha, P. K.; Kinsho, Michikazu; Yamamoto, Shunya*; Okazaki, Hiroyuki*; Taguchi, Tomitsugu*; Yamada, Naoto*; Yamagata, Ryohei*
Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.850 - 854, 2021/10
no abstracts in English
Saha, P. K.; Harada, Hiroyuki; Yoneda, Hitoki*; Michine, Yurina*; Fuchi, Aoi*; Sato, Atsushi*; Shibata, Takanori*; Kinsho, Michikazu
Proceedings of 18th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.656 - 660, 2021/10
2 mMatsubara, Akihiro; Fujita, Natsuko; Kimura, Kenji
Proceedings of the 8th East Asia Accelerator Mass Spectrometry Symposium and the 22nd Japan Accelerator Mass Spectrometry symposium (EA-AMS 8 & JAMS-22), p.57 - 59, 2020/00
no abstracts in English
Saha, P. K.; Harada, Hiroyuki; Kinsho, Michikazu; Sato, Atsushi*; Yoneda, Hitoki*; Michine, Yurina*
Proceedings of 16th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.841 - 845, 2019/07
Kibe, Satoshi; Fujisaku, Kazuhiko*; Sakamoto, Atsushi; Sano, Yuichi; Takeuchi, Masayuki; Suzuki, Hideya; Tsubata, Yasuhiro; Matsumura, Tatsuro
JAEA-Research 2016-024, 40 Pages, 2017/02
JAEA-Research-2016-024.pdf:6.73MB
The Japan Atomic Energy Agency has been developing some flowsheets with TDdDGA (N,N,N,Ntetradodecyldiglycolamide) extractant to recover MA (minor actinide) from raffinate. In this study, countercurrent experiments with the improved flowsheet, e.g. the addition of alcohol into the solvent for preventing the precipitation, were performed using miniature centrifugal contactors in order to compare the extraction/stripping behavior of each element with the mixer-settler type. As a result, no entrainments were observed and sufficient phase separation was achieved by centrifugal contactors without any abnormal fluid behavior, such as overflow. The extraction and stripping of Ln(III) which show the similar tendencies as MA could be achieved successfully, especially their stripping proceeded more efficiently in centrifugal contactors. This might be due to the increase in stripping rates by improving the flowsheet and to superior phase separation performance of centrifugal contactors.
Kobayashi, Jun; Ezure, Toshiki; Tanaka, Masaaki; Kamide, Hideki
Proceedings of 10th Japan-Korea Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-10) (USB Flash Drive), 5 Pages, 2016/11
JAEA has been conducting a design study for an advanced large-scale sodium-cooled fast reactor (SFR). Hot sodium from the fuel subassembly can mix with the cold sodium from the control rod (CR) channel at the bottom of Upper Internal Structure (UIS). Temperature fluctuation due to the fluid mixing at the core outlet may cause high cycle thermal fatigue at the bottom of UIS. JAEA had performed a water experiment to examine countermeasures for the significant temperature fluctuation generated at the bottom of SFRs UIS. Meanwhile, a self-actuated shutdown system (SASS) is equipped in a backup control rod (BCR) channel to ensure reactor shutdown. The BCR guide tubes have a flow guide structure "flow-collector" to provide reliable operation of SASS. Flow-collector may affect the thermal mixing behavior at the bottom of the UIS. This study has investigated the influence of the flow- collector on characteristics of the temperature fluctuation around the BCR channels.
Kibe, Satoshi; Fujisaku, Kazuhiko*; Ambai, Hiromu; Sakamoto, Atsushi; Sano, Yuichi; Takeuchi, Masayuki; Suzuki, Hideya; Tsubata, Yasuhiro; Matsumura, Tatsuro
JAEA-Research 2015-021, 40 Pages, 2016/02
JAEA-Research-2015-021.pdf:2.3MB
The flowsheet with TDdDGA extractant has been being developed for recovering MA from PUREX raffinate. In the previous study, the yields of MA and other elements in countercurrent extraction/stripping experiments using mixer-settlers were not enough for the target and it would be due to the insufficient phase (aqueous/organic) separation. In this study, we carried out countercurrent experiments with surrogate PUREX raffinate using centrifugal contactors which had superior phase separation ability, and evaluated the extraction/stripping behavior of each element. During the operation, abnormal fluid behavior, such as overflow and entrainment, was not observed, and sufficient phase separation was achieved by centrifugal contactors. Extraction behavior of lanthanides was similar to that in mixer-settlers, but their stripping efficiencies decreased. This would be due to shorter residence time in mixing zone.
Kobayashi, Jun; Tanaka, Masaaki; Ohno, Shuji; Ohshima, Hiroyuki; Kamide, Hideki
Proceedings of 16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-16) (USB Flash Drive), p.6664 - 6677, 2015/08
Numerical simulation is recognized an essential tool for the physical phenomena analysis and plant design study of a sodium-cooled fast reactor (SFR). In order to enhance credibility of the numerical results in the activities for plant design by using numerical simulations, it is recognized that verification and validation (V&V) process is very important. In this study, experiments for planar triple parallel jets mixing phenomena conducted in JAEA were proposed as benchmark problems for the code validation in the area of thermal striping study in the SFR development.
Kobayashi, Jun; Ezure, Toshiki; Kamide, Hideki; Oyama, Kazuhiro*; Watanabe, Osamu*
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 6 Pages, 2015/05
A column type upper internal structure (UIS) is installed in the upper plenum of reactor vessel in JSFR. High cycle thermal fatigue may occur at the bottom plate (CIP) of the UIS where the hot sodium from the fuel subassembly can mix with the cold sodium from the control rod channel and the blanket fuel subassembly. We have been conducted a water experiment using a reactor upper plenum model to grasp the thermal-hydraulic phenomena around control rod (CR) channels, and to obtain countermeasures for significant temperature fluctuation on the CIP. The experimental apparatus has 1/3 scale and 60
sector model of the reactor upper plenum. By the experiment, characteristics of fluid temperature fluctuation between the handling head of the assemblies and the CIP are measured and countermeasure for the significant temperature fluctuation generation will be discussed on the influence of the distance from the handling head outlet to the lower surface of the CIP.
Nakamura, Tatsuya; Tanaka, Hiroki; Yamagishi, Hideshi; Soyama, Kazuhiko; Aizawa, Kazuya; Ochi, Atsuhiko*; Tanimori, Toru*
Nuclear Instruments and Methods in Physics Research A, 573(1-2), p.187 - 190, 2007/04
Times Cited Count：9 Percentile：55.15(Instruments & Instrumentation)We have been developing a neutron imaging gas detector with a high spatial resolution and with a high temporal response for the neutron scattering instruments at the pulsed neutron source in the Japan proton accelerator research complex. The gas detector system with individual read-outs was developed to meet the requirements for the instruments for neutron reflectometry or for small angle neutron scattering. The performances of the prototype detector using a multi-wire (MW) or micro-strip (MS) detector head were evaluated using a collimated neutron beam, and we confirmed the MS detector exhibiting a spatial resolution of 1.5 mm and a pulse-pair resolution of about 100 ns with a gas pressure of 6 atm helium with a mixture of 30% CF
. The performances for the MS detector were also evaluated up to the total gas pressure of 8 atm.
Nakamura, Tatsuya; Masaoka, Sei; Yamagishi, Hideshi; Sakasai, Kaoru; Soyama, Kazuhiko; Aizawa, Kazuya
IEEE Transactions on Nuclear Science, 51(4), p.1519 - 1523, 2004/08
Times Cited Count：2 Percentile：18.06(Engineering, Electrical & Electronic)A capillary plate (CP) comprising an assembly of fine glass tubes was applied as a pre-gas-amplification device for a microstrip gas chamber (MSGC) operating under high-gas pressure of helium-3 for use in neutron detection. The collection efficiency of the electrons between the CP and MSGC was maximally 17% using neutrons. The effective gas gain of the detector system was 
600 at a gas pressure of 3 atm with a 10% mixture of ethane with helium-3, confirming the feasibility of the CP as a pre-gas-amplification device. Moreover, we demonstrated that the coincidence measurement of the signals between the CP and the anodes of MSGC decreased the background levels of electronics noise, electronic discharges, and 
-rays, indicating that a detector system with a low background can be constructed using the CP.
Nakamura, Tatsuya; Yamagishi, Hideshi; Masaoka, Sei; Soyama, Kazuhiko; Aizawa, Kazuya
Nuclear Instruments and Methods in Physics Research A, 529(1-3), p.336 - 341, 2004/08
Times Cited Count：6 Percentile：40.10(Instruments & Instrumentation)A microstrip gas chamber (MSGC) with a capability of track discrimination for neutron detection was developed whilst ensuring the stability of the MSGC and fulfilling the specifications required for detectors using in high-flux reactors and high-intensity pulsed-neutron sources. The developed two-dimensional detector system comprises a MSGC with individual signal channel read-outs and a new instrument system with a capability of secondary-particle discrimination (InSPaD). The InSPaD identifies the particles -proton and triton- created in the nuclear reaction 
by a simple, fast and cost-effective method using the difference in the track length, and it enables a small amount of heavy gas such as 
with helium-3 to be used as the filling gas whilst achieving a high spatial resolution.
Nakamura, Tatsuya; Masaoka, Sei; Yamagishi, Hideshi; Soyama, Kazuhiko; Aizawa, Kazuya
Proceedings of ICANS-XVI, Volume 1, p.441 - 446, 2003/07
Development of a Micro-Strip Gas Chamber(MSGC) in JAERI is presented. The performances we aim at are counting rate 
10
, position resolution 
1
, detection efficiency 60% at thermal neutron and good n/gamma discrimination. Our two-dimensional gas detector consists of a micro strip plate printed on a polyimide substrate and a high pressure gas chamber which has all the signal lines are directly taken out (256ch individual readout) and withstands the pressure of 10bar 
. The individual signal readout opens the way to realize high counting rate and high position resolution at the same time. We carried out range measurements of secondary particles to confirm the range measuring power of the MSGC with that read out method. The measured ranges in the gas of 3bar helium mixed with 
ethane is 3mm, 9.5mm for triton and proton, respectively. Those values are well agreed with theoretical estimation and we could show the feasibility of the precise measurement of the ranges by the MSGC.
Masaoka, Sei; Nakamura, Tatsuya; Yamagishi, Hideshi; Soyama, Kazuhiko
JAERI-Research 2003-012, 14 Pages, 2003/06
JAERI-Research-2003-012.pdf:1.58MB
A micro-strip gas chamber (MSGC) using helium-3 gas has been developing as a two-dimensional position sensitive neutron detector for neutron scattering experiments in a high-intensity proton accelerator facility. We have developed the encode board that have built-in FPGAs (Field-Programmable Gate Array). Logics of FPGAs can be freely programmed to carry out digital processing of signals from MSGC and information of the tracks of protons and tritons can be obtained by the encode board. Therefore, the position of neutron capture (more properly the centra of the track) can be calculated by a series of data handling system. As the result of the simulation of a neutron detection experiment, it has proved that the position resolution of less than 1.6 mm can be obtained by using this data handling system.
Hotta, Takashi; Dagotto, E.*
Physica B; Condensed Matter, 312-313(1-4), p.700 - 702, 2002/03
Times Cited Count：2 Percentile：13.96(Physics, Condensed Matter)The crucial role of the orbital degree of freedom is here discussed in order to understand the complex spin and charge structures of transition metal oxides. For manganites, it is shown that diagonal charge stripes in the ferromagnetic phase are induced by the staggered orbital ordered pattern, while for ruthenates, a novel orbital ordering is found to exist in the G-type antiferromagnetic structure, with a hole arrangement as recently observed in X-ray experiments.
Hanada, Masaya; Kashiwagi, Mieko; Morishita, Takatoshi; Taniguchi, Masaki; Okumura, Yoshikazu; Takayanagi, Tomohiro; Watanabe, Kazuhiro
Fusion Engineering and Design, 56-57, p.505 - 509, 2001/10
Times Cited Count：21 Percentile：79.18(Nuclear Science & Technology)no abstracts in English
and Ni on the MgO(100) single crystalVacik, J.; Naramoto, Hiroshi; Narumi, Kazumasa; Yamamoto, Shunya; Miyashita, Kiyoshi*
Materials Research Society Symposium Proceedings, Vol.648, p.P3.50.1 - P3.50.6, 2001/00
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