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Kamiya, Tomohiro; Yoshida, Hiroyuki
Proceedings of the Symposium on Shock Waves in Japan (Internet), 7 Pages, 2024/03
We developed a ghost fluid method satisfying conservation laws to simulate steam explosions that can occur at the accident of a nuclear power plant. In the developed method, a first-order approximation is applied to interface effect regions, and a high-order approximation is applied to bulk regions. In other words, the algorithm of the developed method is not consistent. Therefore, we modify the way of getting ghost fluids and propose a comprehensive algorithm that applies a high-order approximation to interface effect regions. In the presentation, we will report the outlines and results of the numerical tests of it.
Nishida, Akemi
Doboku Gakkai Dai-14-Kai Kozobutsu No Shogeki Mondai Ni Kansuru Shinpojiumu Rombunshu (Internet), 5 Pages, 2024/01
no abstracts in English
Wang, Y. W.*; Wang, H. H.*; Su, Y. H.; Xu, P. G.; Shinohara, Takenao
Materials Science & Engineering A, 887, p.145768_1 - 145768_13, 2023/11
Times Cited Count:1 Percentile:44.33(Nanoscience & Nanotechnology)Takamizawa, Hisashi; Lu, K.; Katsuyama, Jinya; Masaki, Koichi*; Miyamoto, Yuhei*; Li, Y.
JAEA-Data/Code 2022-006, 221 Pages, 2023/02
As a part of the structural integrity assessment research for aging light water reactor (LWR) components, a probabilistic fracture mechanics (PFM) analysis code PASCAL (PFM Analysis of Structural Components in Aging LWR) has been developed in Japan Atomic Energy Agency. The PASCAL code can evaluate failure probabilities and failure frequencies of core region in reactor pressure vessel (RPV) under transients by considering the uncertainties of influential parameters. The continuous development of the code aims to improve the reliability by introducing the analysis methodologies and functions base on the state-of-the-art knowledge in fracture mechanics and domestic data. In the first version of PASCAL, which was released in FY2000, the basic framework was developed for analyzing failure probabilities considering pressurized thermal shock events for RPVs in pressurized water reactors (PWRs). In PASCAL Ver. 2 released in FY 2006, analysis functions including the evaluation methods for embedded cracks and crack detection probability models for inspection were introduced. In PASCAL Ver. 3 released in FY 2010, functions considering weld-overlay cladding on the inner surface of RPV were introduced. In PASCAL Ver. 4 released in FY 2017, we improved several functions such as the stress intensity factor solutions, probabilistic fracture toughness evaluation models, and confidence level evaluation function by considering epistemic and aleatory uncertainties related to influential parameters. In addition, the probabilistic calculation method was also improved to speed up the failure probability calculations. To strengthen the practical applications of PFM methodology in Japan, PASCAL code has been improved since FY 2018 to enable PFM analyses of RPVs subjected to a broad range of transients corresponding to both PWRs and boiling water reactors, including pressurized thermal shock, low-temperature over pressure, and normal operational transients. In particular, the stress intensi
Zarazovski, M.*; Pistra, V.*; Lauerova, D.*; Obermeier, F.*; Mora, D.*; Dubyk, Y.*; Bolinder, T.*; Cueto-Felgueroso, C.*; Szavai, S.*; Dudra, J.*; et al.
Proceedings of ASME 2022 Pressure Vessels and Piping Conference (PVP 2022) (Internet), 11 Pages, 2022/07
Li, Y.; Hirota, Takatoshi*; Itabashi, Yu*; Yamamoto, Masato*; Kanto, Yasuhiro*; Suzuki, Masahide*; Miyamoto, Yuhei*
JAEA-Review 2020-011, 130 Pages, 2020/09
For the improvement of the structural integrity assessment methodology on reactor pressure vessels (RPVs), the probabilistic fracture mechanics (PFM) analysis code PASCAL has been developed and improved in Japan Atomic Energy Agency based on the latest knowledge. The PASCAL code evaluates the failure probabilities and frequencies of Japanese RPVs under transient events such as pressure thermal shock considering neutron irradiation embrittlement. In order to confirm the reliability of the PASCAL as a domestic standard code and to promote the application of PFM on the domestic structural integrity assessments of RPVs, it is important to perform verification activities, and summarize the verification processes and results as a document. On the basis of these backgrounds, we established a working group, composed of experts on this field besides the developers, on the verification of the PASCAL module and the source program of PASCAL was released to the members of working group. This report summarizes the activities of the working group on the verification of PASCAL in FY2016 and FY2017.
Takamizawa, Hisashi; Nishiyama, Yutaka; Hirano, Takashi*
Proceedings of ASME 2020 Pressure Vessels and Piping Conference (PVP 2020) (Internet), 7 Pages, 2020/08
no abstracts in English
Katsuyama, Jinya; Uno, Shumpei*; Watanabe, Tadashi*; Li, Y.
Frontiers of Mechanical Engineering, 13(4), p.563 - 570, 2018/12
Times Cited Count:2 Percentile:11.85(Engineering, Mechanical)For the structural integrity assessments on reactor pressure vessels (RPVs) under pressurized thermal shock (PTS) events, thermal hydraulic (TH) behavior of coolant water is one of the most important influence factors. Configuration of plant equipment and their dimensions, and operator action have large influences on TH behavior. In this study, to investigate the influence of operator action on TH behavior during a PTS event, we developed an analysis model for a typical Japanese plant, and performed TH and structural analyses. Two different operator action times were assumed based on the Japanese and US' rules. From the analysis results, it was clarified that differences in operator action times have a significant effect on TH behavior and loading conditions, that is, following the Japanese rule may lead to lower stresses compared to that when following the US rule because earlier operator action caused lower pressure in the RPV.
Katsuyama, Jinya; Masaki, Koichi; Miyamoto, Yuhei*; Li, Y.
JAEA-Data/Code 2017-015, 229 Pages, 2018/03
As a part of the structural integrity research for aging light water reactor components, a probabilistic fracture mechanics (PFM) analysis code PASCAL has been developed in JAEA. The PASCAL code can evaluate the conditional failure probabilities and failure frequencies for core region in reactor pressure vessels under the pressurized thermal shock events. In this study, we improved many functions such as the stress intensity factor solutions, the fracture toughness models, or confidence level evaluation function by considering epistemic and aleatory uncertainties related to influence parameters in the structural integrity assessment. We also developed the analysis module PASCAL-Manager which calculates the failure frequency for the entire core region taking into consideration the failure probabilities obtained from PACAL-RV. Based on these improvements, the new analysis code is upgraded to PASCAL Ver.4. This report provides the user's manual and theoretical background of PASCAL Ver.4.
Li, Y.; Hayashi, Shotaro*; Itabashi, Yu*; Nagai, Masaki*; Kanto, Yasuhiro*; Suzuki, Masahide*; Masaki, Koichi*
JAEA-Review 2017-005, 80 Pages, 2017/03
For the improvement of the structural integrity assessment methodology on reactor pressure vessels (RPVs), the probabilistic fracture mechanics (PFM) analysis code PASCAL has been developed and improved in JAEA based on latest knowledge. The PASCAL code evaluates the failure probabilities and frequencies of Japanese RPVs under transient events such as pressurized thermal shock considering neutron irradiation embrittlement. In order to confirm the reliability of the PASCAL as a domestic standard code and to promote the application of PFM on the domestic structural integrity assessments of RPVs, it is important to verify the probabilistic variables, functions and models incorporated in the PASCAL and summarize the verification processes and results as a document. On the basis of these backgrounds, we established a working group, composed of experts on this field besides the developers, on the verification of the PASCAL3 which is a PFM analysis module of PASCAL, and the source program of PASCAL3 was released to the members of working group. Through one year activities, the applicability of PASCAL in structural integrity assessments of domestic RPVs was confirmed with great confidence. This report summarizes the activities of the working group on the verification of PASCAL in FY2015.
Lu, K.; Katsuyama, Jinya; Li, Y.
Nihon Kikai Gakkai M&M 2016 Zairyo Rikigaku Kanfuarensu Koen Rombunshu (Internet), p.499 - 501, 2016/10
When conducting structural integrity assessments for reactor pressure vessels (RPVs) subjected to pressurized thermal shock (PTS) events, the stress intensity factor (SIF) is evaluated for a postulated surface crack in the inner surface of RPVs. It is known that the cladding made of a stainless steel is a ductile material which is overlay-welded on the inner surface, therefore, the plasticity of cladding should be considered in SIF calculations for a postulated underclad crack to ensure a conservation evaluation. Recently, the authors performed three-dimensional (3D) elastic and elastic-plastic FEAs for Japanese three-loop RPVs and proposed a rational evaluation method on SIFs of underclad cracks. In this paper, further studies were conducted to discuss the applicability of the proposed plasticity correction method. The effect of neutron irradiation was considered. In addition, different Japanese RPV geometries such as two-loop and four-loop RPVs were also investigated.
Futakawa, Masatoshi; Naoe, Takashi; Kogawa, Hiroyuki; Haga, Katsuhiro; Okita, Kohei*
Experimental Thermal and Fluid Science, 57, p.365 - 370, 2014/09
Times Cited Count:10 Percentile:46.18(Thermodynamics)A liquid mercury target system for a megawatt-class spallation neutron source is being developed in the world. Proton beam is injected to the mercury target to induce spallation reaction. The moment the proton beams bombard the target, pressure waves are generated in the mercury by the thermally shocked heat deposition. The pressure waves excite the mercury target vessel and negative pressure that may cause cavitation along the vessel wall. Gas-bubbles will be injected into the flowing mercury to mitigate the pressure waves and suppress the cavitation inception. The injected gas-bubbles conditions were examined and the effects were predicted experimentally and theoretically from the viewpoints of macroscopic time-scale and microscopic time-scale, i.e. in the former is dominant the interaction between the structural vibration and the pressure in mercury, and in the later is essential the pressure wave propagation process.
Oda, Yasuhisa*; Komurasaki, Kimiya*; Takahashi, Koji; Kasugai, Atsushi; Imai, Tsuyoshi*; Sakamoto, Keishi
Denki Gakkai Rombunshi, A, 126(8), p.807 - 812, 2006/08
Experiments on microwave plasma generation and its application to microwave beamed energy propulsion were conducted using a 1MW-class, 170GHz gyrotron. The microwave beam was focused using a parabola reflector and plasma was initiated near the focal point in the ambient air. Plasma propagated upstream in the microwave beam channel while absorbing microwave. Its propagation velocity was supersonic when the microwave power density was larger than 75kW/cm. The propulsive impulse was measured using a cone-cylinder shaped thruster model. As a result, maximum momentum coupling coefficient was obtained at a certain plasma propagation distance. In addition, large momentum coupling coefficient was obtained when plasma was propagated at a supersonic velocity. It would be because supersonic plasma propagation forms a strong shock wave, resulting in an efficient pressure increase.
Zherebtsov, S.*; Maekawa, Katsuhiro*; Hayashi, Terutake*; Futakawa, Masatoshi
JSME International Journal, Series A, 48(4), p.292 - 298, 2005/10
The effect of temperature on the structure and properties of the type 316 stainless steel alloyed with Al-Si has been reported in the present paper. It has been found that four different types of structure are formed in the alloyed zone depending on the temperature of the substrate. These structures differ from each other in phase composition, microhardness and relation to cracking. Hard, crack-free microstructures are formed at temperatures of about 350 and 750 C. Maintaining the temperature of the sample at 350 C a uniform, crack-free layer with a high hardness is produced by laser alloying with an energy density of 0.76 W/mm.
Futakawa, Masatoshi
Nihon Genshiryoku Gakkai-Shi, 47(8), p.530 - 535, 2005/08
no abstracts in English
Futakawa, Masatoshi
Shindo Gijutsu, (10), p.22 - 26, 2004/11
no abstracts in English
Oda, Yasuhisa*; Komurasaki, Kimiya*; Takahashi, Koji; Kasugai, Atsushi; Sakamoto, Keishi
Denki Gakkai Kenkyukai Shiryo, Genshiryoku Kenkyukai (NE-04-1115), p.19 - 22, 2004/09
no abstracts in English
Wakai, Eiichi; Matsukawa, Shingo; Yamamoto, Toshio*; Kato, Yoshiaki; Takada, Fumiki; Sugimoto, Masayoshi; Jitsukawa, Shiro
Materials Transactions, 45(8), p.2641 - 2643, 2004/08
Times Cited Count:6 Percentile:41.05(Materials Science, Multidisciplinary)no abstracts in English
Sakaki, Hironao; Nakamura, Naoki*; Takahashi, Hiroki; Yoshikawa, Hiroshi
JAERI-Tech 2004-022, 28 Pages, 2004/03
In High Intensity Proton Accelerator Project (J-PARC), the peak current 50mA(max.) proton beam is accelerated to 50GeV. Therefore, when the magnet trouble etc. occurs, and the beam collides toward the accelerating structure, the thermal shock destruction is caused on the surface of the material of the structure. This report shows the design policy of "Prototype-unit for the machine protection system" that is necessary to evade the thermal shock destruction.
Sakaki, Hironao; Nakamura, Naoki*; Takahashi, Hiroki; Yoshikawa, Hiroshi
JAERI-Tech 2004-021, 32 Pages, 2004/03
In High Intensity Proton Accelerator Project (J-PARC), the high-power proton beam is accelerated. If the beam in J-PARC is not stopped at a few micro seconds or less, the fatal thermal shock destruction is caused on the surface of accelerating structure, because of the high-power proton beam. To avoid the thermal shock damage, we designed the high-speed machine protection system. And, the prototype unit for the system was produced. This report shows the result of its performance test.