Decommissioning state of Plutonium Fuel Fabrication Facility; Dismantling the glove box W-9 and equipment interior, and a part of tunnel F1

Nagai, Yuya; Shuji, Yoshiyuki; Kawasaki, Takeshi; Aita, Takahiro; Kimura, Yasuhisa; Nemoto, Yasunori*; Onuma, Takeshi*; Tomiyama, Noboru*; Hirano, Koji*; Usui, Yasuhiro*; et al.

JAEA-Technology 2022-039, 117 Pages, 2023/06

JAEA-Technology-2022-039.pdf:11.96MB

Japan Atomic Energy Agency (JAEA) manages wide range of nuclear facilities. Many of these facilities are required to be performed adjustment with the aging and complement with the new regulatory standards and the earthquake resistant, since the Great East Japan Earthquake and the Fukushima Daiichi Nuclear Power Station accident. It is therefore desirable to promote decommissioning of facilities that have reached the end of their productive life in order to reduce risk and maintenance costs. However, the progress of facility decommissioning require large amount of money and radioactive waste storage space. In order to address these issues, JAEA has formulated a "The Medium/Long-Term Management Plan of JAEA Facilities" with three pillars: (1) consolidation and prioritization of facilities, (2) assurance of facility safety, and (3) back-end countermeasures. In this plan, Plutonium Fuel Fabrication Facility has been selected as primary decommissioned facility, and dismantling of equipment in the facilities have been underway. In this report, size reduction activities of the glove box W-9 and a part of tunnel F-1, which was connected to W-9, are presented, and the obtained findings are highlighted. The glovebox W-9 had oxidation & reduction furnace, and pellet crushing machine as equipment interior. The duration of activity took six years from February 2014 to February 2020, including suspended period of 4 years due to the enhanced authorization approval process

Implementation and performance evaluation of a communication-avoiding GMRES method for stencil-based code on GPU cluster

Matsumoto, Kazuya*; Idomura, Yasuhiro; Ina, Takuya*; Mayumi, Akie; Yamada, Susumu

Journal of Supercomputing, 75(12), p.8115 - 8146, 2019/12

https://doi.org/10.1007/s11227-019-02983-7

A communication-avoiding generalized minimum residual method (CA-GMRES) is implemented on a hybrid CPU-GPU cluster, targeted for the performance acceleration of iterative linear system solver in the gyrokinetic toroidal five-dimensional Eulerian code GT5D. In addition to the CA-GMRES, we implement and evaluate a modified variant of CA-GMRES (M-CA-GMRES) proposed in our previous study to reduce the amount of floating-point calculations. This study demonstrates that beneficial features of the CA-GMRES are in its minimum number of collective communications and its highly efficient calculations based on dense matrix-matrix operations. The performance evaluation is conducted on the Reedbush-L GPU cluster, which contains four NVIDIA Tesla P100 GPUs per compute node. The evaluation results show that the M-CA-GMRES is 1.09x, 1.22x and 1.50x faster than the CA-GMRES, the generalized conjugate residual method (GCR), and the GMRES, respectively, when 64 GPUs are used.

Application of a communication-avoiding generalized minimal residual method to a gyrokinetic five dimensional Eulerian code on many core platforms

Idomura, Yasuhiro; Ina, Takuya*; Mayumi, Akie; Yamada, Susumu; Matsumoto, Kazuya*; Asahi, Yuichi*; Imamura, Toshiyuki*

Proceedings of 8th Workshop on Latest Advances in Scalable Algorithms for Large-Scale Systems (ScalA 2017), p.7_1 - 7_8, 2017/11

https://doi.org/10.1145/3148226.3148234

A communication-avoiding generalized minimal residual (CA-GMRES) method is applied to the gyrokinetic toroidal five dimensional Eulerian code GT5D, and its performance is compared against the original code with a generalized conjugate residual (GCR) method on the JAEA ICEX (Haswell), the Plasma Simulator (FX100), and the Oakforest-PACS (KNL). The CA-GMRES method has higher arithmetic intensity than the GCR method, and thus, is suitable for future Exa-scale architectures with limited memory and network bandwidths. In the performance evaluation, it is shown that compared with the GCR solver, its computing kernels are accelerated by , and the cost of data reduction communication is reduced from to of the total cost at 1,280 nodes.

X-ray absorption spectroscopy in the heavy Fermion compound -YbAlB at high magnetic fields

Terashima, Taku*; Matsuda, Yasuhiro*; Kuga, Kentaro*; Suzuki, Shintaro*; Matsumoto, Yosuke*; Nakatsuji, Satoru*; Kondo, Akihiro*; Kindo, Koichi*; Kawamura, Naomi*; Mizumaki, Masaichiro*; et al.

Journal of the Physical Society of Japan, 84(11), p.114715_1 - 114715_4, 2015/11

https://doi.org/10.7566/JPSJ.84.114715

Synchrotron X-ray spectroscopy study on the valence state and magnetization in -YbAlFeB () at low temperatures and high magnetic fields

Terashima, Taku*; Matsuda, Yasuhiro*; Kuga, Kentaro*; Suzuki, Shintaro*; Matsumoto, Yosuke*; Nakatsuji, Satoru*; Kondo, Akihiro*; Kindo, Koichi*; Kawamura, Naomi*; Mizumaki, Masaichiro*; et al.

Journal of Physics; Conference Series, 592(1), p.012020_1 - 012020_6, 2015/03

https://doi.org/10.1088/1742-6596/592/1/012020

Valence fluctuation phenomena in rare-earth intermetallic compounds have attracted attention because the quantum criticality of the valence transition has been proposed theoretically. Recently, it was found that -YbAlB shows quantum criticality without tuning and has a strong mixed-valence state. In this study, we measured the magnetization curve and X-ray magnetoabsorption in -YbAlFeB (), which is a locally isostructural polymorph of -YbAlB. The magnetization and X-ray experiments were performed in fields up to 55 and 40 T, respectively. A small increase in the Yb valence was observed at fields where the magnetization curve exhibited a change in slope.

Vacuum brazing of the new RFQ for the J-PARC linac

Morishita, Takatoshi; Kondo, Yasuhiro; Hasegawa, Kazuo; Naito, Fujio*; Yoshioka, Masakazu*; Matsumoto, Hiroshi*; Hori, Yoichiro*; Kawamata, Hiroshi*; Saito, Yoshio*; Baba, Hiroshi*

Proceedings of 25th International Linear Accelerator Conference (LINAC 2010) (CD-ROM), p.521 - 523, 2010/09

http://accelconf.web.cern.ch/AccelConf/LINAC2010/papers/tup050.pdf

The fabrication of a new RFQ has been started as a backup machine for the J-PARC linac. The RFQ cavity is divided by three unit tanks in the longitudinal direction. The unit tank consists of two major vanes and two minor vanes, those are brazed together. A one-step vacuum brazing of a unit tank was adopted to unite these four vanes together with the flanges and ports. At the first tank brazing, the vacuum leak has been occurred due to the non-uniform temperature rise during the heating. Repair of this leakage and the results of the improved brazing of the second tank are reported.

Monte-Carlo study based on real coordinates for perpendicularly injected high-energy ions in the LHD high-beta plasma

Seki, Ryosuke*; Matsumoto, Yutaka*; Suzuki, Yasuhiro*; Watanabe, Kiyomasa*; Hamamatsu, Kiyotaka; Itagaki, Masafumi*

Plasma and Fusion Research (Internet), 5, p.014_1 - 014_3, 2010/06

https://doi.org/10.1585/pfr.5.014

no abstracts in English

Thermal characteristics of a new RFQ for J-PARC

Kondo, Yasuhiro; Hasegawa, Kazuo; Morishita, Takatoshi; Matsumoto, Hiroshi*; Naito, Fujio*

Proceedings of 1st International Particle Accelerator Conference (IPAC '10) (Internet), p.780 - 782, 2010/05

http://accelconf.web.cern.ch/AccelConf/IPAC10/papers/mopd043.pdf

A new RFQ for the J-PARC linac is under construction for more stable operation. The requirement of this RFQ is almost same as the now-operating one; the resonant frequency is 324 MHz, the injection energy is 50 keV, the extraction energy is 3 MeV, peak beam current is 30 mA, and RF duty is 1.5%. The resonant frequency tuning during operation will be done by adjusting the temperatures of the cooling waters. We investigate with FEM model both cases; change vane water temperature and change cavity-wall water temperature. The frequency range was 0.35 MHz and 0.28 MHz, respectively. However in the transient analysis, the frequency change of the vane case was smaller than that of the cavity-call case. In this paper, thermal characteristics of this RFQ and control system of the cooling water temperature is described.

Engineering design of RFQ at J-PARC linac

Morishita, Takatoshi; Kondo, Yasuhiro; Hasegawa, Kazuo; Naito, Fujio*; Yoshioka, Masakazu*; Matsumoto, Hiroshi*; Hori, Yoichiro*; Kawamata, Hiroshi*; Saito, Yoshio*; Baba, Hiroshi*; et al.

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.1047 - 1049, 2010/03

http://www.pasj.jp/web_publish/pasj6/papers/fpaca41.pdf

The beam commissioning of J-PARC linac has been started since November 2006. After the scheduled shutdown in summer 2007, the beam is successfully delivered from the linac to the RCS. Since then, a stable beam provision was emphasized. However, the trip in the RFQ was increased at the end of Sept. 2008, then, the stability of the beam operation decreased. To improve this situation, we started to prepare a new RFQ cavity as a backup machine. The basic concept of the engineering design is the simplicity and the effective vacuum pumping aiming at the stable operation. A 3m long cavity is divided into 3 modules longitudinally. A numerical control machining with ball-end mill is chosen for a vane machining. Four vanes are vacuum brazed each other after machining. Each modules are aligned on the platform using a linear motion guide. A basic design of the key components on machining and brazing are described in this proceeding.

Status of the J-PARC RFQ

Hasegawa, Kazuo; Morishita, Takatoshi; Kondo, Yasuhiro; Oguri, Hidetomo; Kobayashi, Tetsuya; Naito, Fujio*; Yoshioka, Masakazu*; Matsumoto, Hiroshi*; Kawamata, Hiroshi*; Hori, Yoichiro*; et al.

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.693 - 695, 2010/03

http://www.pasj.jp/web_publish/pasj6/papers/tpopa03.pdf

The J-PARC RFQ (length 3.1m, 4-vane type, 324 MHz) accelerates a beam from the ion source to the DTL. The beam test of the linac was started in November 2006 and 181 MeV beam was successfully accelerated in January 2007. Since then, the linac has been delivered beams for commissioning of the linac itself, downstream accelerators and facilities. Trip rates of the RFQ, however, suddenly increased in Autumn 2008, and we are suffering from this issue for user run operation. We tried to recover by tender conditioning, modification of RF control, improvement of vacuum and so on. We manage to have beam operation. In this report, we describe the status of the RFQ.