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Takahashi, Kenji*; Inoue, Kazuhiko; Kato, Asao*; Ito, Kei; Fujita, Takafumi*
Transactions of 18th International Conference on Structural Mechanics in Reactor Technology (SMiRT-18), p.3371 - 3380, 2006/03
We carried out reflection seismic and multi-offset VSP surveys at JNC Shobasama-site to develop the investigation technique in the granite area, and evaluated the applicability of these geophysical methods. As the result of this study, we consider that (a) It is possible to infer the existence of the lower angle fracture zone in the granite by reflection seismic survey and (b) Multi-offset VSP supplements the result of reflection seismic survey and it is possible to infer the distribution of the fracture zone in deeper area in the granite.
Hanawa, Satoshi; Sumita, Junya; Shibata, Taiju; Ishihara, Masahiro; Iyoku, Tatsuo; Sawa, Kazuhiro
Transactions of 18th International Conference on Structural Mechanics in Reactor Technology (SMiRT-18), p.600 - 605, 2005/08
no abstracts in English
Sumita, Junya; Shibata, Taiju; Nakagawa, Shigeaki; Hanawa, Satoshi; Iyoku, Tatsuo; Ishihara, Masahiro
Transactions of 18th International Conference on Structural Mechanics in Reactor Technology (SMiRT-18), p.4822 - 4828, 2005/08
Graphite materials are used for structural components in High Temperature Gas-Cooled Reactor (HTGR) core because of their excellent thermo/mechanical properties. Thermal conductivity of graphite components is reduced by neutron irradiation in reactor operation. The reduced conductivity is expected to be recovered by thermal annealing effect when irradiated graphite component is heated above irradiated temperature. In the present study, temperature analyses considering the annealing effect of the HTGR core at a depressurization accident were carried out and influence of annealing effect on maximum fuel temperature was investigated. The analyses show that the annealing effect can reduce the fuel temperature about 100
C at the maximum, and it is possible to evaluate the maximum fuel temperature more appropriately. It was also shown that the core-temperature of High Temperature Engineering Test Reactor (HTTR) at the safety demonstration tests can be analyzed with the developed evaluation method considering annealing effect.
Sakaba, Nariaki; Tachibana, Yukio; Nakagawa, Shigeaki; Hamamoto, Shimpei
Transactions of 18th International Conference on Structural Mechanics in Reactor Technology (SMiRT-18), p.4499 - 4511, 2005/08
Safety demonstration tests using the HTTR are now underway in order to verify the inherent safety features and to improve the safety design and evaluation technologies for HTGRs, as well as to contribute to research and development for the VHTR, which is one of the Generation IV reactor candidates. The coolant flow reduction test by running down gas circulators, which is one of the safety demonstration tests, is a simulation test of anticipated transients without scram. During the coolant flow reduction test, temperature of the high-temperature helium components and chemistry in the primary circuit are changed rapidly. This paper describes the structural integrity assessments of helium components, e.g. helium pipes, heat exchangers, during the coolant flow reduction test. From the result of this evaluation, it was found that the helium components were kept their structural integrity during temperature and chemistry transient condition in the coolant flow reduction test from the reactor power at 30%. It was also confirmed by this assessment that the coolant flow reduction test will be able to perform with its enough safety margins from the reactor power at 100%.
Chikazawa, Yoshitaka
Transactions of 18th International Conference on Structural Mechanics in Reactor Technology (SMiRT-18), 0 Pages, 2005/08
A new particle method for elastic and creep structures is developed. This method is based on the concept of MPS (Moving particle semi-implicit) method which was developed for fluid dynamics. Particle interaction models for differential operators are prepared in MPS method. The government equations of elastic structures are interpreted into interactions among particles. Using the present particle method, elastic interactions are revealed to be equivalent to connections between normal and tangential springs. Therefore the present particle method is simple and corresponding physical meaning is clear. A model for creep deformation is represented to replace these elastic springs into creep ones using Blackburn model. A tensile 304SS bar with steady load is analyzed. The calculated result is compared with analytical and experimental results and is in good agreement with them. A tensile stainless steel plate with steady strain is analyzed. The stress relaxation with creep strain is compared with experimental results and is in good agreement with it.
Shigeki, Okamura; Kitamura, Seiji; Takahashi, Kenji
Transactions of 18th International Conference on Structural Mechanics in Reactor Technology (SMiRT-18), 0 Pages, 2005/08
In Japan, several kinds of three-dimensional seismic isolation system for next-generation nuclear power plant such as fast reactors have been studied in recent years. We proposed a structural concept of a vertical component isolation system, assuming a building adopting a horizontal base isolation system. In this concept, a reactor vessel and major primary components are suspended from a large common deck supported by isolation devices consisting of large coned disk springs. In order to verify the isolation performance of the vertical component isolation system, 1/8 series of shaking table tests using a scale model were conducted. The test model was composed of 4 vertical isolation devices, common deck and horizontal load suspension system which supports the horizontal load by the earthquake. For the design earthquake, the system smoothly operated, and sufficient isolation characteristics were shown. The examination on the horizontal load suspension system was carried out. The simulation analysis results matched well the test results, so the validity of the design technique was able to be verified. As the result, the prospect that the vertical isolation system applied to the FBR plant could technically realize was obtained.
Kasahara, Naoto; Nakamura, Kyotada; Ito, Kei; Shibamoto, Hiroshi; Nagashima, Hideaki; Inoue, Kazuhiko
Transactions of 18th International Conference on Structural Mechanics in Reactor Technology (SMiRT-18), p.1131 - 1140, 2005/08
We carried out reflection seismic and multi-offset VSP surveys at JNC Shobasama-site to develop the investigation technique in the granite area, and evaluated the applicability of these geophysical methods. As the result of this study, we consider that a) It is possible to infer the existence of the lower angle fracture zone in the granite by reflection seismic survey and b) Multi-offset VSP supplements the result of reflection seismic survey and it is possible to infer the distribution of the fracture zone in deeper area in the granite.