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Journal Articles

Dynamic PRA of flooding-initiated accident scenarios using THALES2-RAPID

Kubo, Kotaro; Zheng, X.; Tanaka, Yoichi; Tamaki, Hitoshi; Sugiyama, Tomoyuki; Jang, S.*; Takata, Takashi*; Yamaguchi, Akira*

Proceedings of 30th European Safety and Reliability Conference and 15th Probabilistic Safety Assessment and Management Conference (ESREL 2020 and PSAM-15) (Internet), p.2279 - 2286, 2020/11

Probabilistic risk assessment (PRA) is one of the methods used to assess the risks associated with large and complex systems. When the risk of an external event is evaluated using conventional PRA, a particular limitation is the difficulty in considering the timing at which nuclear power plant structures, systems, and components fail. To overcome this limitation, we coupled thermal-hydraulic and external-event simulations using Risk Assessment with Plant Interactive Dynamics (RAPID). Internal flooding was chosen as the representative external event, and a pressurized water reactor plant model was used. Equations based on Bernoulli's theorem were applied to flooding propagation in the turbine building. In the analysis, uncertainties were taken into account, including the flow rate of the flood water source and the failure criteria for the mitigation systems. In terms of recovery action, isolation of the flood water source by the operator and drainage using a pump were modeled based on several assumptions. The results indicate that the isolation action became more effective when combined with drainage.

Journal Articles

Case study on sampling techniques using machine learning and simplified physical model for simulation-based dynamic probabilistic risk assessment

Kubo, Kotaro; Zheng, X.; Ishikawa, Jun; Sugiyama, Tomoyuki; Jang, S.*; Takata, Takashi*; Yamaguchi, Akira*

Proceedings of Asian Symposium on Risk Assessment and Management 2020 (ASRAM 2020) (Internet), 11 Pages, 2020/11

Dynamic probabilistic risk assessment (PRA) enables a more realistic and detailed analysis than classical PRA. However, the trade-off for these improvements is the enormous computational cost associated with performing a large number of thermal-hydraulic (TH) analyses. In this study, based on machine learning (ML), we aim to reduce these costs by skipping the TH analysis. For the ML algorithm, we selected a support vector machine; we built it using a high-fidelity/high-cost detailed model and low-fidelity/low-cost simplified model. As a result, the computational costs could be reduced by approximately 80% without significantly decreasing the accuracy under the assumed conditions.

Journal Articles

A Comparative study of sampling techniques for dynamic probabilistic risk assessment of nuclear power plants

Kubo, Kotaro; Zheng, X.; Tanaka, Yoichi; Tamaki, Hitoshi; Sugiyama, Tomoyuki; Jang, S.*; Takata, Takashi*; Yamaguchi, Akira*

Proceedings of Joint International Conference on Supercomputing in Nuclear Applications + Monte Carlo 2020 (SNA + MC 2020), p.308 - 315, 2020/10

Dynamic probabilistic risk assessment (PRA) is a method for improving the realism and completeness of conventional PRA. However, enormous calculation costs are incurred by these improvements. One solution is to select an appropriate sampling method. In this paper, we applied the Monte Carlo, Latin hypercube, grid-point, and quasi-Monte Carlo sampling methods to the dynamic PRA of a simplified accident sequence and compared the results for each method. Quasi-Monte Carlo sampling was found to be the most effective method in this case.

Journal Articles

Worker dose under high-power operation of the J-PARC 3 GeV Rapid Cycling Synchrotron

Yamamoto, Kazami

EPJ Web of Conferences, 153, p.07022_1 - 07022_6, 2017/09

 Times Cited Count:1 Percentile:69.68

The J-PARC 3 GeV Rapid Cycling Synchrotron (RCS) delivers a 1-MW, high-intensity beam to the following facilities. In such high-intensity accelerator, the operational beam intensity is limited to keep the exposure to the workers by the residual dose within acceptable tolerances. Therefore we continue to commission the accelerator system to reduce the beam loss. In order to achieve further high-intensity operation, the J-PARC accelerator system was drastically upgraded (Increment of the injection energy of RCS and peak current of Linac) over the past two years. After the upgrade, the beam loss was decreased by the commissioning. The output power was increased; nevertheless the residual doses were kept same level or decreased. Since we replaced the broken collimator which was higher activated, we kept the exposure to the workers within acceptable level.

Journal Articles

Progress and status of the J-PARC 3 GeV RCS

Kinsho, Michikazu

Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.3382 - 3384, 2014/07

Big issue for the J-PARC rapid cycling synchrotron (RCS) was displacement of main magnets caused by last big earthquake because this made beam loss more than 400 kW beam power. Since realignment of main magnets and other components was essential to realize higher beam power and stable operation, this work has been done during maintenance period in 2013. To achieve the nominal performance 1MW beam power at the RCS and 0.75 MW at the MR, beam energy of linac was increased from 181 MeV to 400 MeV with a new accelerating structure ACS (Annular-ring Coupled Structure) linac from this January. It was successful 400 MeV beam injection and 3 GeV beam extraction at the RCS, and user operation has been performed with beam power of 300 kW. An equivalent beam power of 560 kW with a beam loss of only 0.3% could be achieved during short time for high intensity beam study.

Journal Articles

J-PARC and new era of science

Oyama, Yukio

Nuclear Instruments and Methods in Physics Research A, 562(2), p.548 - 552, 2006/06

 Times Cited Count:10 Percentile:59.81(Instruments & Instrumentation)

High Intensity Proton Accelerator Project promoted jointly by Japan Atomic Energy research Institute (JAERI) and High Energy Accelerator Research Organization (KEK), named as J-PARC was started on April 1, 2001. The project was merged from the projects promoted by the both institutes, called Neutron Science Project and Japan Hadron Project, respectively. The accelerator complex of J-PARC consists of three accelerators: 400 MeV Linac, 3 GeV rapid cycle synchrotron and 50 GeV synchrotron, and four major experimental facilities: Material & Life Science Facility, Nuclear & Particle Physics (Hadron) Facility, Neutrino Facility and Nuclear Transmutation Experiment Facility. The present construction phase, Phase-I, excludes nuclear transmutation facility. The accelerators will be completed in 2007 with 200 MeV Linac, and an operation will start. The Neutrino facility will be completed in 2008 and the 200-400 MeV Linac will be constructed in 2008-2010.

Journal Articles

Rapid dissolution techniques with microwave heating devices for solidified products made from non-metallic wastes by plasma melting

Haraga, Tomoko; Kameo, Yutaka; Nakashima, Mikio

Bunseki Kagaku, 55(1), p.51 - 54, 2006/01

 Times Cited Count:4 Percentile:15.3(Chemistry, Analytical)

A relatively large quantity of sample solutions have to be prepared for radiochemical analysis of solidified products yielded by plasma melting treatment of non-metallic radioactive wastes. In order to dissolve the solidified products sample rapidly, dissolution method with microwave heating devices was applied. In a conventional method only by external heating with various mixtures of acids (HNO$$_{3}$$, HF, HClO$$_{4}$$ and H$$_{2}$$SO$$_{4}$$), a 0.1 g amount of the sample was dissolved with difficulty. However, applying the microwave assisted dissolution method, a 1 g amount of the sample was completely dissolved in a shorter time. Thereby the time for dissolution procedures was shortened less than a one-tenth. The present dissolution method was successfully applied to the blast furnace slag as a reference material to determine main elements with good precision.

Journal Articles

Reproducibility of thermal neutron flux distribution on patient's brain surface with a realistic phantom

Yamamoto, Kazuyoshi; Kumada, Hiroaki; Yamamoto, Tetsuya*; Matsumura, Akira*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(2), p.193 - 199, 2004/06

To investigate the possibility of experimental approach for dose evaluation using a realistic phantom that faithfully reproduced the shape of a head, this research considered the manufacture of a patient's realistic phantom and the reappearance of actual medical irradiation conditions. We selected the rapid prototyping technology to produce the realistic phantom from the Computed Tomography (CT) imaging. This phantom was irradiated under the same clinical irradiation condition of this patient, and the thermal neutron distribution on the brain surface was measured in detail. Several subjects on material and data conversion in the production of realistic phantom were mentioned. As a result of reproducing medical irradiation using the realistic phantom, the maximum thermal neutron flux became a value about 22% lower than the surface of the actual brain. If the problems pointed out in this paper are solved, it may also be expected that it would become possible to check computational dosimetry system.

JAEA Reports

Design report on the 3-GeV proton beam transport facility (3NBT) of High Intensity Proton Accelerator facility (J-PARC)

Sakamoto, Shinichi; Meigo, Shinichiro; Konno, Chikara; Kai, Tetsuya; Kasugai, Yoshimi; Harada, Masahide; Fujimori, Hiroshi*; Kaneko, Naokatsu*; Muto, Suguru*; Ono, Takehiro*; et al.

JAERI-Tech 2004-020, 332 Pages, 2004/03


One of the experimental facilities in Japan Proton Accelerator Research Complex (J-PARC) is the Materials and Life Science Experimental Facility (MLF), where high-intensity neutron beams and muon beams are used as powerful probes for materials science, life science and related engineering. The neutrons and muons are generated with high-intensity proton beam from 3-GeV rapid cycling synchrotron (RCS). The high-intensity proton beam has to be effectively transported, and a neutron production target and a muon production target have to be also properly irradiated. The principal design of the 3-GeV proton beam transport facility (3NBT) is systematized.

Journal Articles

Quick sample preparation for analysis of dioxins in flue gas from municipal solid waste incinerator

Takigami, Machiko; Arai, Hidehiko*; Hirota, Koichi; Taguchi, Mitsumasa; Hakoda, Teruyuki; Kojima, Takuji

Kankyo Kagaku, 14(1), p.13 - 23, 2004/03

The Japan Atomic Energy Research Institute undertook a pilot scale electron beam decompostion of dioxins in the flue gases from the municipal solid waste incinerator at the Takahama Clean Center. The conventional method, following the Japan Industrial Standards (JIS) method, takes 2 weeks at least to extract and purify dioxins from the flue gases for analysis by GC/MS. However, using a carbon adsorbent, the time required for the extraction of dioxins was shortened from 16 to 2.5 hours. Further improvements in the clean up process enabled the overall time to be reduced to less than a half of that rquired by the JIS method. Using this simplified method allows analysts, who are not practiced in the pretreatment of flue gases, to prepare samples for dioxin analysis by GC/MS. The sampling and pretreatment of the flue gases can, with this process, be completed within 4 days with accuracy comparable to JIS method.

Journal Articles

Development of automated measurement device for low-level radioactive contamination on building surfaces

Tachibana, Mitsuo; Ito, Hirokuni*; Hatakeyama, Mutsuo*; Yanagihara, Satoshi

Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(1), p.120 - 127, 2004/03

The RAPID-1600 was developed to measure a low-level radioactive contamination on building surfaces automatically. The double layered detectors are structured by two gas flow type detectors with a $$beta$$ rays shielding plate between the two detectors and it is horizontally positioned. The lower counter measures $$beta$$ and $$gamma$$ rays and the upper counter measures $$gamma$$ rays. The $$beta$$ rays counting rates are derived by subtracting $$gamma$$ rays counting rates of the upper counter from $$gamma$$ and $$beta$$ rays counting rates of the lower counter. This mechanism results in sensitive to $$beta$$ rays against to low background radiation conditions. The driving unit can move omnidirectionally by controlling two driving wheels individually, and has a capability to correct its position if an orbital error is detected by the self-position identification system. The RAPID-1600 was successfully applied to the actual measurement in the radioisotope production facilities. The RAPID-1600 is expected to be a useful tool for measurement of radioactivity in decommissioning nuclear facilities.

Journal Articles

Design of beam optics in the proton beam transport line from synchrotron to spallation neutron target

Meigo, Shinichiro; Noda, Fumiaki*; Fujimori, Hiroshi*; Ikeda, Yujiro

Proceedings of ICANS-XVI, Volume 3, p.967 - 976, 2003/07

In J-PARC project, spallation target is irradiated by 3 GeV proton beam of 1 MW. Due to hands on maintenance for the proton beam lines, loss of proton beam is limited less than 1 W/m. Since it is difficult to predict the phase space distribution of the proton beam, we decided that the beam line have to be larger acceptance for 324 $$pi$$ mrad, which is determined by the collimator located in the synchrotron. Distortion of proton beam is caused by the by the instability of angle at the extraction of 3-GeV synchrotron, miss alignment of the magnet, and un-uniformity of the magnet field. In this study, the distortion is calculated. In order to fit the conditions, the stability of extraction angles should be kept smaller than 0.2 mrad. As for the magnetic field, it is found that the uniformity should be kept better 5x10$$^{-4}$$ and 2x10$$^{-3}$$ for bending and quadruple magnets, respectively. It is also found the error of alignments should be limited smaller than 1.0 mm and 1.0 mrad.

JAEA Reports

Production of a faithful realistic phantom to human head and thermal neutron flux measurement on the brain surface (Cooperative research)

Yamamoto, Kazuyoshi; Kumada, Hiroaki; Kishi, Toshiaki; Torii, Yoshiya; Endo, Kiyoshi*; Yamamoto, Tetsuya*; Matsumura, Akira*; Uchiyama, Junzo; Nose, Tadao*

JAERI-Tech 2002-092, 23 Pages, 2002/12


Thermal neutron flux is determined using the gold wires in current BNCT irradiation, so evaluation of arbitrary points after the irradiation is limited in the quantity of these detectors. In order to make up for the weakness, dose estimation of a patient is simulated by a computational dose calculation supporting system. In another way without computer simulation, a medical irradiation condition can be replicate experimentally using of realistic phantom which was produced from CT images by rapid prototyping technique. This phantom was irradiated at a same JRR-4 neutron beam as clinical irradiation condition of the patient and the thermal neutron distribution on the brain surface was measured in detail. This experimental evaluation technique using a realistic phantom is applicable to in vitro cell irradiation experiments for radiation biological effects as well as in-phantom experiments for dosimetry under the nearly medical irradiation condition of patient.

Journal Articles

Nonlocal transport phenomena and various structure formations in plasmas; Introduction

Kishimoto, Yasuaki

Purazuma, Kaku Yugo Gakkai-Shi, 78(9), p.857 - 860, 2002/09

In order to understand the various phenomena related to the nonlocal transport and structure formation in the plasma, we reviw the topics in the field of (1)laser implosion plasma, (2)space plasma, and (3) magnetic fusion plasma, as a spatial series.

Journal Articles

Comparison of dosimetry by the realistic patient head phantom and by the patient's brain, and the JCDS calculation; A Clinical dosimetry study

Endo, Kiyoshi*; Matsumura, Akira*; Yamamoto, Tetsuya*; Nose, Tadao*; Yamamoto, Kazuyoshi; Kumada, Hiroaki; Kishi, Toshiaki; Torii, Yoshiya; Kashimura, Takanori*; Otake, Shinichi*

Research and Development in Neutron Capture Therapy, p.425 - 430, 2002/09

Using the Rapid Prototyping Technique, we produced a realistic phantom as a formative model of a patient head. This realistic phantom will contribute to verification of our planning system. However, cross-correlation among the calculations using the JAERI Computational Dosimetry System (JCDS), the realistic phantom, and the in vivo measurements were not fully completed because of the difficulty involved in modeling a post-surgical brain and a thermal neutron shield. The experimental simulation technique using the realistic phantom is a useful tool for more reliable dose planning for the intraoperative BNCT.

Journal Articles

Design of a dipole magnet for the 3-GeV proton synchrotron of the JAERI/KEK joint project

Tani, Norio; Kanazawa, Kenichiro; Shimada, Taihei; Suzuki, Hiromitsu; Watanabe, Yasuhiro; Adachi, Toshikazu*; Someya, Hirohiko*

Proceedings of 8th European Particle Accelerator Conference (EPAC 2002), p.2376 - 2378, 2002/00

The 3-GeV synchrotron proposed in the JAERI/KEK Joint Project is a rapid-cycling synchrotron (RCS), which accelerates a high-intensity proton beam from 400 MeV to 3 GeV at a repetition rate of 25 Hz. The 3-GeV synchrotron is used to produce pulsed spallation neutrons and muons. It also works as an injector for a 50-GeV synchrotron. Since the magnets for the 3-GeV synchrotron are required to have a large aperture in order to realize the large beam power of 1 MW, there is a large leakage field at an end part than a usual synchrotron magnet. In addition, 25-Hz ac field induces an eddy current in magnet components: e.g. a coil, magnet end plates and etc. We intend to use a stranded conductor as a coil conductor so that the eddy current induced in the coil can be reduced. On the other hand, the eddy current induced in the end plates is expected to be large. Therefore, it is important to investigate an effect of the large leakage field and the eddy current to the beam motion around the magnet end part. We have constructed a prototype dipole magnet and field measurement system for this purpose. This paper reports the results of the design and the preliminary test about this magnet.

Journal Articles

Development of a computer-controlled on-line rapid ion-exchange separation system

Tsukada, Kazuaki*; Otsuki, Tsutomu*; Sueki, Keisuke*; *; *; *; Nakahara, Hiromichi*; Shinohara, Nobuo; ; Usuda, Shigekazu; et al.

Radiochimica Acta, 51(2), p.77 - 84, 1990/00

no abstracts in English

JAEA Reports

Journal Articles

Rapid ion-exchange separations of actinides

Journal of Radioanalytical and Nuclear Chemistry, 123(2), p.619 - 631, 1988/02

 Times Cited Count:22 Percentile:87(Chemistry, Analytical)

no abstracts in English

Journal Articles

Rapid anion exchange separation of berkelium with (III) mineral acid-methyl alcohol mixtures

; *; ;

Journal of Radioanalytical and Nuclear Chemistry, Letters, 117(6), p.329 - 336, 1987/06

no abstracts in English

34 (Records 1-20 displayed on this page)