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81.
Residual stress determination in a dissimilar weld overlay pipe by neutron diffraction 总被引:2,自引:0,他引:2
Wanchuck Woo Vyacheslav EmCamden R. Hubbard Ho-Jin LeeKwang Soo Park 《Materials Science and Engineering: A》2011,528(27):8021-8027
Residual stresses were determined through the thickness of a dissimilar weld overlay pipe using neutron diffraction. The specimen has a complex joining structure consisting of a ferritic steel (SA508), austenitic steel (F316L), Ni-based consumable (Alloy 182), and overlay of Ni-base superalloy (Alloy 52M). It simulates pressurized nozzle components, which have been a critical issue under the severe crack condition of nuclear power reactors. Two neutron diffractometers with different spatial resolutions have been utilized on the identical specimen for comparison. The macroscopic ‘stress-free’ lattice spacing (do) was also obtained from both using a 2-mm width comb-like coupon. The results show significant changes in residual stresses from tension (300-400 MPa) to compression (−600 MPa) through the thickness of the dissimilar weld overlay pipe specimen. 相似文献
82.
S.A. Manoshin A.V. Belushkin S.A. Kulikov E.P. Shabalin K. Walther C. Scheffzuek V.V. Zhuravlev 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2009,608(3):447-453
Neutron guides are widely used to transport the neutrons from the moderator to the sample. Due to the constructive features of the ring corridor of the fast pulsed reactor IBR-2, the minimal distance between the moderator and the guide entrance is around 6 m. The main goal of the paper is to optimize the neutron optical system between the moderator and the entrance of the new neutron guides. Using Monte Carlo simulations we calculate the possible best gain of the neutron flux density at the guide exit. After the described optimization process, the optimal system is obtained. The recommendations for construction of the new beam line are provided too. Similar technique and the proposed system could be easily adapted for another similar beam line at the neutron sources. 相似文献
83.
84.
A polynomial expansion scheme is used to solve Boltzmann neutron transport equation in the case of strongly anisotropic neutral particles forward–backward scattering. 相似文献
85.
M. Retuerto M.J. Martínez-Lope M. García-Hernández J.A. Alonso 《Materials Research Bulletin》2009,44(6):1261-5414
Two samples of the double perovskite Sr2FeReO6 have been synthesized by (1) soft-chemistry procedures and (2) high-pressure methods. The sample prepared by a soft-chemistry technique presents 75% of Fe/Re cationic order whereas the one prepared by the application of high external pressure generates a complete Fe/Re cationic order. Both materials have been characterized by X-ray diffraction, neutron powder diffraction and magnetic measurements. The magnetic properties of both oxides have been compared, observing that the specimen prepared via soft-chemistry procedures presents an enhanced Curie temperature of 445 K, although the sample prepared under high-pressure techniques displays a superior saturation magnetization. This behavior is explained as a consequence of the presence, in the partially disordered sample, of Fe-rich islands containing strong Fe-O-Fe antiferromagnetic couplings, able to nucleate and lock the ferromagnetic interactions of the ordered regions, thus increasing the global Curie temperature of the partially disordered material. 相似文献
86.
Effect of Fe doping on structure,magnetic and electrical properties La0.7Ca0.3Mn0.5Fe0.5O3 manganite
N.T. Dang V.S. Zakhvalinskii D.P. Kozlenko The-Long Phan S.E. Kichanov S.V. Trukhanov A.V. Trukhanov Yu.S. Nekrasova S.V. Taran S.V. Ovsyannikov S.H. Jabarov E.L. Trukhanova 《Ceramics International》2018,44(13):14974-14979
The crystal and magnetic structures of La0.7Ca0.3Mn0.5Fe0.5O3 compound have been studied by neutron powder diffraction in the temperature range of 10–300 К. The magnetization and electrical resistivity measurements have been also performed in the temperature range of 5–300?K in magnetic fields up to 1?T. These experimental results indicate a formation of a complex magnetic state in which the long-range antiferromagnetic G-type phase coexists with the short-range ferromagnetic clusters. The electrical conductivity of La0.7Ca0.3Mn0.5Fe0.5O3 demonstrates an anomalous temperature behavior suggesting a switching between different states. The origin of the unconventional magnetic state, the mechanisms of the electrical conductivity, and correlation between magnetic and transport properties in this manganite have been discussed. 相似文献
87.
For a fixed-source calculation in a multiplying system, the variance in the neutron-chain length can create an unstable calculation and a neutron flux with high variance. In this paper an analytical frame is derived to calculate a priori the variance of the neutron flux in a simple model of a fixed-source calculation. This method is then used to find better variance reduction techniques not only for this simplified problem, but also for general cases. 相似文献
88.
ZHANG Peng WITTMANN F H ZHAO TieJun LEHMANN E & JIN ZuQuan Center for Durability & Sustainability Studies of Sh ong Province Qingdao Technological University Qingdao China Aedificat Institute Freiburg Freiburg D- Germany 《中国科学:信息科学(英文版)》2010,(5)
Water movement in porous cement-based materials is of great importance when studying their deterioration processes and durability.Many traditional methods based on mass changes,electricity or nuclear magnetic resonances are available for studying water transport in cement-based materials.In this research,an advanced technique i.e.thermal neutron radiography was utilized to achieve visualization and quantification of time dependent water movement including water penetration and moisture vapor in porous cemen... 相似文献
89.
Masayuki Ohta Keitaro Kondo Masayuki Matsunaka Hiroyuki Miyamaru Isao Murata Toshiyuki Iida Kentaro Ochiai Chikara Konno 《Fusion Engineering and Design》2009,84(7-11):1446-1449
Integral benchmark experiments with DT neutrons are not always sufficient for nuclear data benchmarking in the MeV region, below 10 MeV. A neutron spectrum shifter, which will be placed between a sample and a DT neutron source, is effective to moderate DT neutrons incident to the sample. In order to estimate effects of the spectrum shifter, the ratio of the contribution of 14 MeV neutrons in the leakage neutron and gamma-ray spectra was calculated with MCNP-4C for an experimental configuration at FNS of JAEA, Japan. The calculations were carried out for a Li2TiO3 sample with a Be, D2O, or 7LiD spectrum shifter. It was found out that the Be shifter was superior to others and the Be shifter was effective to decrease the contribution of 14 MeV neutrons especially for secondary gamma-ray spectrum measurements. 相似文献
90.
Ryuichi Tayama Katsumi Hayashi a Ryo Iwasaki Masana Sasaki Yoshinori Etoh Hiroshi Sakurai 《Nuclear Engineering and Design》2001,210(1-3):239-248
A neutron-scanning device was developed for measuring accurate neutron densities of BWR high burn-up fuels up to 65 GWd tU−1. Characteristic test of this device was done with a 252Cf source and adopted to measure axial distributions of neutron densities of BWR spent fuels with various enrichments (2.0–3.4%), which had been irradiated up to 60 GWd tU−1 at Fukushima Daini Nuclear Power Station Unit 2(2F-2). We found the measured neutron densities were proportional to about fourth power of the corresponding burn-up values. The neutron densities calculated by the ORIGEN2.1 code and various cross section libraries showed good agreements with the measured ones in profile and absolute value except for BWR-UE file mainly based on ENDF/B-IV. The BS240J32 library based on JENDL3.2 was the best among the investigated libraries. 相似文献