Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Nishino, Saki; Okada, Jumpei; Watanabe, Kazuki; Furuuchi, Yuta; Yokota, Satoru; Yada, Yuji; Kusaka, Shota; Morokado, Shiori; Nakamura, Yoshinobu
JAEA-Technology 2023-011, 39 Pages, 2023/06
JAEA-Technology-2023-011.pdf:2.51MB
Tokai Reprocessing Plant (TRP) which shifted to decommissioning phase in 2014 had nuclear fuel materials such as the spent fuel sheared powder, the diluted plutonium solution and the uranium solution in a part of the reprocessing main equipment because TRP intended to resume reprocessing operations when it suspended the operations in 2007. Therefore, we have planned to remove these nuclear materials in sequence as Flush-out before beginning the decommissioning, and conducted removal of the spent fuel sheared powder as the first stage. The spent fuel sheared powder that had accumulated in the cell of the Main Plant (MP) as a result of the spent fuel shearing process was recovered from the cell floor, the shearing machine and the distributor between April 2016 and April 2017 as part of maintenance. Removing the recovered spent fuel sheared powder was conducted between June 2022 and September 2022. In this work, the recovered powder was dissolved in nitric acid at the dissolver in a small amount in order to remove it safely and early, and the dissolved solution was sent to the highly radioactive waste storage tanks without separating uranium and plutonium. Then, the dissolved solution transfer route was rinsed with nitric acid and water. Although about 15 years had passed since previous process operations, the removing work was successfully completed without any equipment failure because of the organization of a system that combines veterans experienced the operation with young workers, careful equipment inspections, and worker education and training. Removing this powder was conducted after revising the decommissioning project and obtaining approval from the Nuclear Regulation Authority owing to operating a part of process equipment.
Tanai, Kenji; Horita, M.*; Dewa, Katsuyuki*; Goke, Mitsuo*
JNC TN8410 2001-026, 116 Pages, 2002/03
JNC-TN8410-2001-026.pdf:9.19MB
Earthquake resistance for the underground structure is higher than the ground structure. Therefore, the case of examining the earthquake resistance of underground structure was little. However, it carries out the research on the aseismic designing method of underground structure, since the tunnel was struck by Hyogo-ken Nanbu Earthquake, and it has obtained a much knowledge. However, an object of the most study was behavior at earthquake of the comparatively shallow underground structure in the alluvial plain board, and it not carry out the examination on behavior at earthquake of underground structure in the deep rock mass. In the meantime, underground disposal facility of the high level radioactive waste constructs in the deep underground, and it carries out the operation in these tunnels. In addition, it has made almost the general process of including from the construction start to the backfilling to be about 60 years (Japan Nuclear Fuel Cycle Development Institute, 1999). During these periods, it is necessary to also consider the earthquake resistance as underground structure from the viewpoint of the safety of facilities. Then, it extracted future problem as one of the improvement of the basis information for the decision of the safety standard and guideline of the country on earthquake-resistant design of the underground disposal facility, while it carried out investigation and arrangement of earthquake-resistant design cases, guidelines and analysis method on existing underground structure, etc.. And, the research item for the earthquake resistance assessment of underground structure as case study of the underground research laboratory.
Ezaki, Tetsuro*; Jinno, Kenji*; Mitani, Yasuhiro*; *; Uchida, Masahiro; *
JNC TY8400 2000-004, 94 Pages, 2000/03
JNC-TY8400-2000-004.pdf:7.73MB
no abstracts in English
Yang Zumao*;
JNC TN9400 2000-009, 81 Pages, 2000/02
JNC-TN9400-2000-009.pdf:47.3MB
It is important to study thermal stratification and striping phenomena for they can induce thermal fatigue failure of structures. This presentation uses the AQUA code, which has been developed in Japan Nuclear Cycle Development Institute (JNC), to investigate the characteristics of these thermal phenomena in water, liquid sodium, liquid lead and carbon dioxide gas. There are altogether eight calculated cases with same Richardson number and initial inlet hot velocity in thermal stratification calculations, in which four cases have same velocity difference between inlet hot and cold fluid, the other four cases with same temperature difference. The calculated results show : (1) The fluid's properties and initial conditions have considerable effects on thermal stratification, which is decided by the combination of such as thermal conduction, viscous dissipation and buoyant force, etc., and (2) The gas has distinctive thermal stratification characteristics from those of liquid because for
Takachi, Kazuhiko; Taniguchi, Wataru
JNC TN8400 99-042, 68 Pages, 1999/11
The buffer material is expected to maintain its low water permeability, self-sealing properties, radionuclides adsorption and retardation properties, thermal conductivity, chemical buffering properties, overpack supporting properties, stress buffering properties, etc. over a long period of time. Natural clay is mentioned as a material that can relatively satisfy above. Among the kinds of natural clay, bentonite when compacted is superior because (1)it has exceptionally low water permeability and properties to control the movement of water in buffer, (2)it fills void spaces in the buffer and fractures in the host rock as it swells upon water uptake, (3)it has the ability to exchange cations and to adsorb cationic radioelements. In order to confirm these functions for the purpose of safety assessment, it is necessary to evaluate buffer properties through laboratory tests and engineering-scale tests, and to make assessments based on the ranges in the data obtained. This report describes the procedures, test conditions, results and examinations on the buffer material of dynamic triaxial tests, measurement of elastic wave velocity and liquefaction tests that aim at getting hold of dynamic mechanical properties. MWe can get hold of dependency on the shearing strain of the shearing modulus and hysteresis damping constant, the application for the mechanical model etc. by dynamic triaxial tests, the acceptability of maximum shearing modulus obtained from dynamic triaxial tests etc. by measurement of elastic wave velocity and dynamic strength caused by cyclic stress etc. by liquefaction tests.
S.M.Spiessberger*; K.Humer*; H.W.Weber*; E.K.Tschegg*; H.Gerstenberg*; Udagawa, Akira
Advances in Cryogenic Engineering Materials, Vol.44, p.191 - 195, 1998/00
no abstracts in English
PNC TJ1412 97-002, 157 Pages, 1997/03
None
; *; *; Shibata, Katsuyuki
Proc. of 14th Int. Conf. on Structural Mechanics in Reactor Technology, 7, p.475 - 482, 1997/00
no abstracts in English
Tsukimori, Kazuyuki
PNC TN9410 95-203, 17 Pages, 1995/08
A mechanical hold down method is under discussion as the means to prevent fuel assemblies from being lifted up in the scope of investigation of the recycle reactor conception at Plant Engineering Section. The device of the mechanical hold down system is a coil spring. In this case it is necessary to maintain enough pressure force in high temperature region. Therefore, it is needed to analize creep behaviors of coil springs. At this stage it is desirable to survay parametrically the creep behaviors of various dimensions of coil springs rather than to analize detailed behaviors by FEM. This paper describes the investigation of a creep behavior analysis method of coil springs. In the development process of the method the torque of the spring is derived from the assumption of shear stress field and hear distribution of shear strain in the radius direction and the constitutive equation of creep, and finally the spring force can be obtained by the equilibrium equation as the function of time. For implementation of this method a simple program should be created since the shear stress distribution in the radius direction is nonlinear, however, a wide ranged parametric survay can be done on the creep behavior of coil springs of arbitrary shape, dimension and material.
; Sakai, Toshiyuki*; Sanyoshi, Hirotaka; Iwasaki, Isao*; Kuribayashi, Masakazu*;
PNC TN8410 95-056, 65 Pages, 1995/03
None
Tsukimori, Kazuyuki
PNC TN9410 95-042, 313 Pages, 1995/02
Prevention of the buckling under seismic loading is an important issue, since vessels and piping components of Fast Breeder Reactor(FBR) plants are generally thin wall structures. A research and development on the shear/bending buckling of thin-walled cylindrical shells as the basic structure models has been proceeded since 1987-FY in order to rationalize the safety margin in the structural design of FBR components and to realize the sophistication of design. As the result, an analytical evaluation method of the buckling strength of cylindrical shells under shear loading, which is avalable within a wide range of dimensions and for various materials, has been proposed. Present study is located on the extension of this R&D and is focused on the effect of the interaction between shear and bending loading which is not considered in the previous buckling strength evaluation method. The examination of the interaction effects are implemented from the following three points of view. (1)The maximum values of stress indeces such as the difference between two principal stresses and their location. (2)The investigation of the interaction effects in the transition region between shear mode dominant buckling and bending mode dominant one based on the elastic buckling eigen-value analysis. (3)Development of an analytical evaluation method of the shear-bending interaction due to the propagation of plasticity, based on the idea that the shear stress and the axial stress are not dependent each other in the elastic-plastic region.Obtained results are followings. (1)No changes are found in the maximum values of the principal stress difference or the equivalent stress and their locations between the pure shear or the pure bending case and the shear and bending combined case. (2)Though a little effect due to the interaction between shear and bending loads is observed from elastic eigen value analyses, the effect of the interaction due to plasticity is dominant in the inelastic ...
