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Journal Articles

Verification of a probabilistic fracture mechanics code PASCAL4 for reactor pressure vessels

Lu, K.; Katsuyama, Jinya; Li, Y.; Miyamoto, Yuhei*; Hirota, Takatoshi*; Itabashi, Yu*; Nagai, Masaki*; Suzuki, Masahide*; Kanto, Yasuhiro*

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 9 Pages, 2019/05

Journal Articles

Nuclear structure of $$^{76}$$Ni from the ($$p$$,$$2p$$) reaction

Elekes, Z.*; Kripk$'o$, $'A$*; Sohler, D.*; Sieja, K.*; Ogata, Kazuyuki*; Yoshida, Kazuki; Doornenbal, P.*; Obertelli, A.*; Authelet, G.*; Baba, Hidetada*; et al.

Physical Review C, 99(1), p.014312_1 - 014312_7, 2019/01

 Percentile:100(Physics, Nuclear)

The nuclear structure of the $$^{76}$$Ni nucleus was investigated by ($$p$$,$$2p$$) reaction using a NaI(Tl) array to detect the deexciting prompt $$gamma$$ rays. A new transition with an energy of 2227 keV was identified by $$gamma gamma$$ and $$gamma gamma gamma$$ coincidences. Our shell-model calculations using the Lenzi, Nowacki, Poves, and Sieja interaction produced good candidates for the experimental proton hole states in the observed energy region, and the theoretical cross sections showed good agreement with the experimental values. Although we could not assign all the experimental states to the theoretical ones unambiguously, the results are consistent with a reasonably large Z = 28 shell gap for nickel isotopes in accordance with previous studies.

Journal Articles

Development of crack evaluation models for probabilistic fracture mechanics analyses of Japanese reactor pressure vessels

Lu, K.; Masaki, Koichi; Katsuyama, Jinya; Li, Y.

Proceedings of 2018 ASME Pressure Vessels and Piping Conference (PVP 2018), 8 Pages, 2018/07

Journal Articles

Development of probabilistic fracture mechanics analysis code PASCAL Version 4 for reactor pressure vessels

Lu, K.; Masaki, Koichi; Katsuyama, Jinya; Li, Y.; Uno, Shumpei*

Proceedings of 2018 ASME Pressure Vessels and Piping Conference (PVP 2018), 10 Pages, 2018/07

Journal Articles

Development of stress intensity factors for subsurface flaws in plates subjected to polynomial stress distributions

Lu, K.; Mano, Akihiro; Katsuyama, Jinya; Li, Y.; Iwamatsu, Fuminori*

Journal of Pressure Vessel Technology, 140(3), p.031201_1 - 031201_11, 2018/06

 Percentile:100(Engineering, Mechanical)

Journal Articles

An Estimation method of flaw distributions reflecting inspection results through Bayesian update

Lu, K.; Miyamoto, Yuhei*; Mano, Akihiro; Katsuyama, Jinya; Li, Y.

Proceedings of Asian Symposium on Risk Assessment and Management 2017 (ASRAM 2017) (USB Flash Drive), 9 Pages, 2017/11

Nowadays, probabilistic fracture mechanics (PFM) has been utilized in several countries as a rational method for structural integrity assessment of important structural components such as reactor pressure vessels (RPVs). In PFM analyses, potential flaws in target components are used to evaluate the failure probability or frequency. Therefore, flaw distributions (i.e., flaw depth and density distributions) in an RPV shall be rationally set as one of the most important influential factors, which are developed during the manufacturing process such as welding. Recently, a Bayesian updating methodology was applied to reflect the inspection results into flaw distributions, and the likelihood functions applicable to the case when flaws are detected in inspections were proposed. However, there may be no flaw indication as the inspection results of some RPVs. The flaw distributions in this situation are important while the corresponding likelihood functions have not been proposed. Therefore, this study proposed likelihood functions to be applicable for both case when flaws are detected and when there is no flaw indication as the inspection results. Based on the proposed likelihood functions, several application examples were given in which flaw distributions were estimated by reflecting the inspection results through Bayesian update. The results indicate that the proposed likelihood functions are useful for estimating the flaw distribution for the case when there is no flaw indication as the inspection results.

Journal Articles

Shell evolution beyond $$Z$$=28 and $$N$$=50; Spectroscopy of $$^{81,82,83,84}$$Zn

Shand, C. M.*; Podoly$'a$k, Zs.*; G$'o$rska, M.*; Doornenbal, P.*; Obertelli, A.*; Nowacki, F.*; Otsuka, T.*; Sieja, K.*; Tostevin, J. A.*; Tsunoda, T.*; et al.

Physics Letters B, 773, p.492 - 497, 2017/10

 Times Cited Count:8 Percentile:14.67(Astronomy & Astrophysics)

Journal Articles

Probabilistic fracture mechanics analysis models for Japanese reactor pressure vessels

Lu, K.; Katsuyama, Jinya; Uno, Shumpei; Li, Y.

Proceedings of 2017 ASME Pressure Vessels and Piping Conference (PVP 2017) (CD-ROM), 8 Pages, 2017/07

Journal Articles

$$gamma$$ decay of unbound neutron-hole states in $$^{133}$$Sn

Vaquero, V.*; Jungclaus, A.*; Doornenbal, P.*; Wimmer, K.*; Gargano, A.*; Tostevin, J. A.*; Chen, S.*; N$'a$cher, E.*; Sahin, E.*; Shiga, Yoshiaki*; et al.

Physical Review Letters, 118(20), p.202502_1 - 202502_5, 2017/05

 Times Cited Count:8 Percentile:18.97(Physics, Multidisciplinary)

Journal Articles

Investigation on the plasticity correction of stress intensity factor calculations for underclad cracks in reactor vessels

Lu, K.; Katsuyama, Jinya; Li, Y.

Nippon Kikai Gakkai M&M 2016 Zairyo Rikigaku Kanfarensu 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.

Journal Articles

Comparison of stress intensity factor solutions for surface cracks with high aspect ratio

Nagai, Masaki*; Lu, K.; Kamaya, Masayuki*

Nippon Kikai Gakkai M&M 2016 Zairyo Rikigaku Kanfarensu Koen Rombunshu (Internet), p.481 - 483, 2016/10

In nuclear power plants, a number of cracks attributed to stress corrosion cracking (SCC) have been detected in welds made with nickel alloy weld metals. One of the characteristics of these cracks is that crack aspect ratio $$a/l$$ is greater than 0.5, where a is the crack depth and $$l$$ is the crack length. When a crack is detected in components of nuclear power plants during in-service inspection, flaw evaluation is conducted according to the requirement of codes such as JSME Rules on Fitness-for-Service for Nuclear Power Plants. Here, the stress intensity factor plays an important role for predicting crack growth behavior due to fatigue and/or SCC. Although several solutions of the stress intensity factor are already given in the JSME code, no solutions are available for the cracks with $$a/l >$$ 0.5. According to the current code, surface cracks with $$a/l >$$ 0.5 are characterized as semi-circular shape $$l = 2a$$. To evaluate these cracks in a rational manner, several solutions have been proposed for cracks with $$a/l >$$ 0.5. In this paper, comprehensive comparison was made between solutions for cracks $$a/l >$$ 0.5, and benchmark analysis on SCC crack growth was performed.

Journal Articles

Stress intensity factor solutions for subsurface flaws in plates subjected to polynomial stress distributions

Lu, K.; Katsuyama, Jinya; Li, Y.; Iwamatsu, Fuminori*

Proceedings of 2016 ASME Pressure Vessels and Piping Conference (PVP 2016) (Internet), 7 Pages, 2016/07

Stress intensity factor (SIF) solutions for subsurface flaws near the free surface in plates were numerically investigated based on the finite element analyses. The flaws with aspect ratios $$a/l$$ = 0, 0.1, 0.2, 0.3, 0.4 and 0.5, the normalized ratios $$a/d$$ = 0, 0.1, 0.2, 0.4, 0.6 and 0.8 and $$d/t$$ = 0.01 and 0.1 were taken into account, where a is the half flaw depth, l is the flaw length, $$d$$ is the distance from the center of the subsurface flaw to the nearest free surface and t is the wall thickness. Fourth-order polynomial stress distributions in the thickness direction were considered. In addition, probabilistic fracture mechanics analyses were also performed and some example solutions obtained in this work were used to evaluate the conditional probability of failure of a reactor pressure vessel under a pressurized thermal shock event. The results indicated that the numerical SIF solutions calculated in this study are effective in engineering applications.

Journal Articles

Fatigue lives of multiple flaws in accordance with combination rule

Lu, K.; Li, Y.; Hasegawa, Kunio; Lacroix, V.*

Proceedings of 2016 ASME Pressure Vessels and Piping Conference (PVP 2016) (Internet), 7 Pages, 2016/07

Journal Articles

Plasticity correction on the stress intensity factor evaluation for underclad cracks under pressurized thermal shock events

Lu, K.; Katsuyama, Jinya; Li, Y.

Proceedings of 2016 ASME Pressure Vessels and Piping Conference (PVP 2016) (Internet), 8 Pages, 2016/07

Journal Articles

Stress intensity factor solutions for subsurface elliptical cracks in flat plates subjected to polynomial stress distributions

Lu, K.; Katsuyama, Jinya; Li, Y.

Nippon Kikai Gakkai M&M 2015 Zairyo Rikigaku Kanfarensu Koen Rombunshu (Internet), 3 Pages, 2015/11

In this paper, the stress intensity factor (SIF) solutions for subsurface elliptical cracks near the free surface in flat plates were numerically investigated based on finite element analyses. The cracks with aspect ratios $$a/l$$ = 0, 0.1, 0.2, 0.3, 0.4 and 0.5, normalized ratios $$a/d$$ = 0, 0.1, 0.2, 0.4, 0.6 and 0.8 and $$d/t$$ = 0.1 were taken into account, where a is the crack half-depth, $$l$$ is the crack length, $$d$$ is the distance from subsurface crack to the nearest free surface and $$t$$ is the wall thickness. Fourth-order polynomial stress distributions in the thickness direction were considered. It was concluded that the numerical SIF solutions presented in the paper are useful in engineering applications.

Journal Articles

Shell evolution beyond $$N$$=40; $$^{69,71,73}$$Cu

Sahin, E.*; Doncel, M.*; Sieja, K.*; de Angelis, G.*; Gadea, A.*; Quintana, B.*; G$"o$rgen, A.*; Modamio, V.*; Mengoni, D.*; Valiente-Dob$'o$n, J. J.*; et al.

Physical Review C, 91(3), p.034302_1 - 034302_9, 2015/03

 Times Cited Count:16 Percentile:13.65(Physics, Nuclear)

Journal Articles

From a single-band metal to a high-temperature superconductor via two thermal phase transitions

He, R.-H.*; Hashimoto, Makoto*; Karapetyan, H.*; Koralek, J. D.*; Hinton, J. P.*; Testaud, J. P.*; Nathan, V.*; Yoshida, Yoshiyuki*; Yao, H.*; Tanaka, Kiyohisa*; et al.

Science, 331(6024), p.1579 - 1583, 2011/03

 Times Cited Count:210 Percentile:0.96(Multidisciplinary Sciences)

The nature of the pseudogap phase of cuprate high-temperature superconductors is a major unsolved problem in condensed matter physics. We studied the commencement of the pseudogap state at temperature $$T^*$$ using three different techniques (angle-resolved photoemission spectroscopy, polar Kerr effect, and time-resolved reflectivity) on the same optimally doped Bi2201 crystals. We observed the coincident, abrupt onset at $$T^*$$ of a particle-hole asymmetric antinodal gap in the electronic spectrum, a Kerr rotation in the reflected light polarization, and a change in the ultrafast relaxational dynamics, consistent with a phase transition. Upon further cooling, spectroscopic signatures of superconductivity begin to grow close to the superconducting transition temperature ($$T_c$$), entangled in an energy-momentum dependent manner with the preexisting pseudogap features, ushering in a ground state with coexisting orders.

Journal Articles

Angular distributions of protons scattered by $$^{40}$$Ar nuclei with excitation of the 2$$^{+}$$ (1.46 MeV) and 3$$^{-}$$ (3.68 MeV) collective levels for incident energies of 25.1, 32.5, and 40.7 MeV

Okumusoglu, N. T.*; Gorur, F. K.*; Birchall, J.*; Soukhovitskij, E. Sh.*; Capote, R.*; Quesada, J. M.*; Chiba, Satoshi

Physical Review C, 75(3), p.034616_1 - 034616_10, 2007/03

 Times Cited Count:3 Percentile:66.77(Physics, Nuclear)

Elastic and inelastic scattering of unpolarized and polarized protons by $$^{40}$$Ar nuclei for incident energies between 20 and 50 MeV has been studied by reanalyzing experimental scattering spectra for the 2$$^{+}$$ (1.46 MeV) and 3$$^{-}$$ (3.68 MeV) levels in the angular range 30$$^{circ}$$ - 160$$^{circ}$$ for incident protons of energies of 25.1, 32.5, and 40.7 MeV. An isospin dependent soft-rotator coupled channels optical model with the potential containing a dispersive term with a nonlocal contribution is used to analyze the data.

Journal Articles

Beam-palarization asymmetries for the $$p$$($$overrightarrow{gamma}$$,$$K$$$$^{+}$$)$$Lambda$$ and $$p$$($$overrightarrow{gamma}$$,$$K$$$$^{+}$$)$$Sigma$$$$^{0}$$ reactions for $$E$$$$_{gamma}$$=1.5-2.4 GeV

Zegers, R. G. T.*; Sumihama, Mizuki*; Ahn, D. S.*; Ahn, J. K.*; Akimune, Hidetoshi*; Asano, Yoshihiro; Chang, W. C.*; Dat$'e$, S.*; Ejiri, Hiroyasu*; Fujimura, Hisako*; et al.

Physical Review Letters, 91(9), p.092001_1 - 092001_4, 2003/08

 Times Cited Count:119 Percentile:4.52(Physics, Multidisciplinary)

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