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Matsushita, Kentaro; Ezure, Toshiki; Imai, Yasutomo*; Fujisaki, Tatsuya*; Tanaka, Masaaki
Nihon Kikai Gakkai Kanto Shibu Ibaraki Koenkai 2021-Nendo Koen Rombunshu (Internet), 4 Pages, 2021/08
For evaluation of gas entrainment phenomenon at free surface in reactor vessel of sodium-cooled fast reactor, the gas entrainment evaluation tool named "Stream Viewer" has been developed. In Stream Viewer, depth of surface vortex dimple is predicted by calculating pressure decrease at the vortex center using velocity distribution around the vortex and Burgers vortex model. In this report, a method to identify continuous vortex center lines from a velocity distribution is newly developed. It becomes possible to evaluate three-dimensional distribution of pressure decrease along vortex center line. Then, the method is validated by applying Stream Viewer to an open channel experiment. As the result, it was confirmed that vortex center lines were successfully identified by the improved Stream Viewer. Moreover, it was also shown that the evaluation accuracy of gas entrainment was expected to be improved by considering distribution of pressure decrease along vortex center line.
Matsushita, Kentaro; Fujisaki, Tatsuya*; Ezure, Toshiki; Tanaka, Masaaki; Uchida, Mao*; Sakai, Takaaki*
Keisan Kogaku Koenkai Rombunshu (CD-ROM), 26, 6 Pages, 2021/05
For the gas entrainment vortex at the free surface in sodium-cooled fast reactors, development of the numerical analysis method to evaluate amount of the gas entrainment from the free surface has been developing. In this paper, the automatic creation of analysis meshes which can suppress the calculation cost while maintaining the prediction accuracy of the vortex shape is investigated, and the adaptive mesh refinement (AMR) method is examined to the creation of analysis mesh applying to the unsteady vortex system. The refined mesh based on the criterion evaluated by vorticity, Q-value as second invariant of the velocity and the discriminant for the eigen equation of the velocity gradient tensor is considered, and it found that the AMR method based on Q-value can refine the analysis meshes most efficiently.
Takase, Kazuyuki; Yoshida, Hiroyuki; Ose, Yasuo*
Hai Pafomansu Komputingu To Keisan Kagaku Shimpojium (HPCS 2005) Rombunshu, P. 16, 2005/01
no abstracts in English
Matsui, Shingo*; Muto, Yasushi*; Shiina, Yasuaki
Nihon Genshiryoku Gakkai Wabun Rombunshi, 2(2), p.175 - 186, 2003/06
no abstracts in English
Sato, Haruo
JNC TN8400 99-064, 22 Pages, 1999/10
Four kinds of diffusion experiments; (1)through-diffusion(T-D) experiments for compaction direction dependency, (2)in-diffusion(I-D) experiments for composition dependency of silica sand in bentonite, (3)I-D experiments for initial bentonite gain size dependency, and (4)I-D experiments for the restoration property of an artificial single fracture in compacted bentonite, were carried out using tritiated water which is a non-sorbing nuclide to evaluate the effect of pore structural factors for eompacted bentonite on diffudion. For(1), effective diffusivities (De) in Na-bentonites, Kunigel-V1 and Kunipia-F were measured for 1.0 and 1.5 Mg
m
. For(2), apparent diffusivities (Da) in Kunigel-V1 were measured for 0.8, 1.4 and 1.8 Mgm with silica sand of 30 and 50 wt%. For(3), Da values for 0.8, 1.4 and 1.8 Mgm were measured for a granulated Na-bentonite, OT-9607 which grain-size distribution is in a rang between 0.1 and 5 mm. For (4), Da values in Kunigel-V1 which a single fracture was artificially reproduced and was immersed in distilled water for 7 or 28 days for the restoration of the fracture, were measured for 1.8 Mgm. Although De values in Kunigel-V1 were approximately the same for both compacted directions over the density, De values for perpendicular direction to compacted direction were higher than those for the same direction as compacted direction in Kunipia-F. For composition dependency of silica sand in bentonite, no significant effect of the mixure of silica sand in bentonite on Da was found. For initial bentonite grain size dependency, Da values obtained for OT-960 were approximately the same as those for Kunigel-V1 and no effect of initial grain size of bentonite on diffusion was found. For the restoration property of a single fracture in compacted bentonite, no restoration period dependency on Da was found. Based on this, it may be said that diffusion of nuclides in compacted bentonite, ...
Kasahara, Naoto; Yacumpai, A.*; Takasho, Hideki*
JNC TN9400 99-019, 34 Pages, 1999/02
At incomplete mixing area of high temperature and low temperature fluids near the surface of structures, temperature fluctuation of fluid gives thermal fatigue damage to wall structures. This thermohydraulic and thermomechanical coupled phenomenon is called thermal striping, which has so complex mechanism and sometimes causes crack initiation on the structural surfaces that rational evaluation methods are required for screening rules in design codes. In this study, frequency response characteristics of structures and its mechanism were investigated by both numerical and theoretical methods. Based on above investigation, a structural response diagram was derived, which can predict stress amplitude of structures from temperature amplitude and frequency of fluids. Furthermore, this diagram was generalized to be the Non-dimensional structural response diagram by introducing non-dimensional parameters such as Biot number, non-dimensional frequency, and non-dimensional stress. The use of the Non-dimensional structural response diagram appears to evaluate thermal stress caused by thermal striping, rapidly without structural analysis, and rationally with considering attenuation by non-stationary heat transfer and thermal unloading. This diagram can also give such useful information as sensitive frequency range to adjust coupled thermohydraulic and thermomechanical analysis models taking account of four kinds of attenuation factors: turbulent mixing, molecular diffusion, non-stationaly heat transfer, and thermal unloading.
Brear, D. J.
PNC TN9410 98-005, 53 Pages, 1998/01
When liquid fuel makes contact with steel structure the liquid can freeze as a crust and the structure can melt at the surface. The melting and freezing processes that occur can influence the mode of fuel freezing and hence fuel relocation. Furthermore the temperature gradients established in the fuel and steel phases determine the rate at which heat is transferred from fuel to steel. In this memo the 1-D transient heat conduction equations are applied to the case of initially liquid UO
brought into contact with solid steel using up-to-date materials properties. The solutions predict criteria for fuel crust formation and steel melting and provide a simple algorithm to determine the interface temperature when one or both of the materials is undergoing phase change. The predicted steel melting criterion is compared with available experimental results.
Sato, Haruo
PNC TN8410 97-202, 205 Pages, 1998/01
This thesis summarizes the results investigated in order to establish a basic theory on the predictive method of diffusion coefficients of nuclides in compacted sodium bentonite which is a candidate buffer material and in representative rocks for the geological disposal of radioactive waste by measuring the pore structural factors of the compacted bentonite and rocks such as porosity and tortuosity, measuring diffusion coefficients of nuclides in the bentonite and rocks, acquiring basic data on diffusion and developing diffusion models which can quantitatively predict nuclide migration in long-term. This consists of 7 chapters. Chapter 1 is the introduction, in which conventional studies on nuclide migration in buffer materials and rocks for the geological disposal of radioactive waste carried out to date are reviewed, and those problems are summarized as well as the objectives of this study are described. Besides, the difinition of geological disposal is explained. In Chapter 2, it is described on non-steady state diffusion of HTO, Sr-90, Tc-99, I-129, Cs-137, Np-237, Am-241 and Pu in purified sodium bentonite, Kunipia-F, in which the rate of constituent Na-smectite was raised approximately 100wt%. In-diffusion experiments were carried out in a range of bentonite densities of 200 
2000 kgm under ambient aerobic conditions at room temperature (20 23
C), and apparent diffusion coefficients (Da) were obtained. The apparent diffusion coefficients decreased with increasing dry density of bentonite. It was quantitatively indicated from diffusion experiments using HTO that these Da values include the effect of geometric retardation such as the tortuosity factor of compacted bentonite. It was experimentally clarified that Da is not affected by diffusion time based on diffusion experiments for different experimental periods using Sr and Cs. Moreover, it was also experimentally clarified that Da is not affected by tracer ...
Fumizawa, Motoo; Kunugi, Tomoaki; Hishida, Makoto; *; Fujii, Sadao*; Igarashi, Minoru*
Nuclear Technology, 110, p.263 - 272, 1995/05
Times Cited Count：4 Percentile：43.23(Nuclear Science & Technology)no abstracts in English
Konishi, Satoshi; Yamanishi, Toshihiko; Enoeda, Mikio; Hayashi, Takumi; Ohira, Shigeru; Yamada, Masayuki; Suzuki, Takumi; Okuno, Kenji; Sherman, R. H.*; Willms, R. S.*; et al.
Fusion Engineering and Design, 28, p.258 - 264, 1995/00
Times Cited Count：4 Percentile：43.46(Nuclear Science & Technology)no abstracts in English
Proc. of the First Int. Symp. on Thermal Stresses and Related Topics (Thermal Stresses 95), 0, p.99 - 102, 1995/00
no abstracts in English
*; *; *; *
PNC TJ9124 94-009, 164 Pages, 1994/03
In selecting the reasonable DBL on steam generator, it is indicated that the possibility of failure propagation due to overheating should be evaluated. In this study, the general plan for the next models to evaluate the reasonable DBL have been designed; a)overheating tube bursting models (structural/fractural dynamics), b)unsteady heat conduction analysis models, c)blow down analysis models and d)reaction zone temperature distribution analysis models. Then blow down analysis models were developed to evaluate the overheating tube bursting and analysis code was preliminarily designed in which the module construction of this code and link of each modules were described. Furthermore, easy coupling of this code and LEAP in future was fully considered.
Nagashima, Keisuke; Koide, Yoshihiko; Shirai, Hiroshi
Nuclear Fusion, 34(3), p.449 - 454, 1994/00
Times Cited Count：67 Percentile：94.74(Physics, Fluids & Plasmas)no abstracts in English
Hayashi, Koji
JAERI-M 93-041, 152 Pages, 1993/03
no abstracts in English
*; *; Akiyama, Mamoru*; Fumizawa, Motoo
Proc. of the 2nd ASME/JSME Nuclear Engineering, p.151 - 156, 1993/00
no abstracts in English
Fujii, Sadao*; *; Igarashi, Minoru*; Fumizawa, Motoo; Kunugi, Tomoaki; Hishida, Makoto
Proc. of the 6th Int. Topical Meeting on Nuclear Reactor Thermal Hydraulics,Vol. 2, p.1498 - 1505, 1993/00
no abstracts in English
Hayashi, Koji
Nihon Genshiryoku Gakkai-Shi, 34(10), p.971 - 983, 1992/10
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)no abstracts in English
*; *; Akiyama, Mamoru*; Fumizawa, Motoo
Proc. of the 2nd JSME-KSME Thermal Engineering Conf. Vol. 1, p.2-459 - 2-462, 1992/00
no abstracts in English
Fumizawa, Motoo; Ogawa, Masuro; Hishida, Makoto; Okamoto, Koji*
FLUCOME-91, p.333 - 338, 1991/00
no abstracts in English
