Estimation of reactivity worth with differential operator sampling method

Nagaya, Yasunobu; Mori, Takamasa

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 6 Pages, 2010/10

Nuclear reactor analysis requires calculations of reactivity worth such as control rod worth, void reactivity worth, sample reactivity worth, etc. It is, however, difficult to perform such calculations with the Monte Carlo method if the worth is small. In the present work, we extend the differential operator sampling method such that the derivative terms up to the fourth-order and the perturbed source effect up to the fourth-order can be estimated, and examine the applicability of the fourth-order differential operator sampling method to reactivity worth calculations. As a benchmark calculation, we perform the reactivity worth calculation for Godiva. The perturbation is introduced by decreasing the density in the central region of a radius of 1 cm. The result with the fourth-order differential operator sampling method agrees well with the reference one. As a practical calculation, we also perform Np sample worth calculation for TCA. The calculated sample reactivity worth with the differential sampling method approaches to the reference value as the higher-order effect is taken into account up to the fourth order. However, there still exists a discrepancy of 17%. It is, thus, found that many more higher-order effects must be taken into account or another method must be applied in this case.

Full-scale 3D vibration simulator for an entire nuclear power plant on the simple orchestration application framework

Kim, G.; Nakajima, Kohei*; Teshima, Naoya; Tatekawa, Takayuki; Suzuki, Yoshio; Takemiya, Hiroshi

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 5 Pages, 2010/10

Full-Scale 3D vibration simulator for an entire nuclear power plant is a seismic response analysis system for a whole digitalized nuclear power plant. In the system, boundary data from large components are used as input data of small components. To make a whole simulation efficient, we introduced pipeline method in which the data were transferred each time step running all components simulations in parallel. In the realization of the method on grid, since there were no existing grid technologies to sufficiently support the method for a long time, we developed simple orchestration application framework (SOAF) and using the SOAF, we performed seismic response analysis of a test reactor of JAEA and succeeded simulation for a week.

Application integration control system for multi-scale and multi-physics simulation

Kino, Chiaki; Tatekawa, Takayuki; Teshima, Naoya; Kim, G.; Suzuki, Yoshio; Araya, Fumimasa; Nishida, Akemi; Takemiya, Hiroshi

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 4 Pages, 2010/10

In the present study, we have developed a new control system for application integration with the fault-tolerant API (FT-API). The system treats an application as a task which consists of one job and multiple file transfer. Firstly, each task designates a computer to submit a job using a scheduler associated to the job. Secondly, all files which are necessary to execute the job are gathered in the computer using FT-API for file transfer. Finally, the job is submitted using FT-API for job execution. If the computer is outage, the task designates a new computer, gathers necessary files and submits a new job. Each scheduler, file transfer and job condition can be flexibly defined in XML. This time, we applied the system to fluid-structure interaction analysis simulation. The result indicates that the system enables a user to easily execute multi-scale and multi-physics simulation using application integration.

Verification of detailed two-phase flow simulation code TPFIT to water jet experiment

Yoshida, Hiroyuki; Suzuki, Takayuki*; Takase, Kazuyuki; Koizumi, Yasuo*

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 4 Pages, 2010/10

Kinetic Monte Carlo annealing simulation of cascade damage in -Fe

Suzudo, Tomoaki; Golubov, S.*; Stoller, R.*; Yamaguchi, Masatake; Tsuru, Tomohito; Kaburaki, Hideo

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 6 Pages, 2010/10

Molecular dynamics is a useful tool to analyze cascade damage in structural materials of nuclear devices, but the time scale accessible to molecular dynamics is 100 ps. Kinetic Monte Carlo annealing simulation of cascade damage is useful for analyzing the longer time development of cascade damage. We conducted a series of such annealing simulations in -Fe. The surviving displacement ratio to the NRT displacements before annealing is 0.3 in the case of primary knock-on atom's energy more than 10 keV, but it decreased by 30 % through the annealing at 300 K because of recombination of vacancies and self-interstitial atoms, and the recombination ratio increased as the annealing temperature increased. These results are meaningful when applied to the simulation of accumulation of cascades using rate theory. This work is useful for R&D of nuclear materials.

A Numerical simulation of I in the atmosphere emitted from nuclear fuel reprocessing plants

Nishizawa, Masato; Suzuki, Takashi; Nagai, Haruyasu; Togawa, Orihiko

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 4 Pages, 2010/10

Suzuki et al. (, , 268-275, 2008) estimated that more than 80% of Iodine-129 (I) in seawater in the Japan Sea came from nuclear fuel reprocessing plants. Considering the distance from the main nuclear reprocessing plants in Europe to the Japan Sea and the time scales of atmospheric and ocean circulations, large portion of I in the Japan Sea is presumed to be transported through the atmosphere. In the present study, a global chemical transport model, MOZART-4, is applied to investigate the behavior of I emitted from nuclear fuel reprocessing plants in Europe (Sellafield in the UK and La Hague in France) and to estimate the distribution in the atmosphere and deposition in remote sites. The result of numerical simulation for more than fifty-year period from the 1950s is validated by comparison with measurements of I around the world and analyzed to clarify the characteristic of the distributions of concentration and deposition of I. The modeled concentrations of I in precipitation in Europe and depositions in Japanese waters are in the same order as measurements. The emitted I to the atmosphere is distributed and deposited all over the Northern Hemisphere due to the prevailing westerlies. The emission of I to the atmosphere is thus important in considering the transport and deposition of I to remote sites.

Development of an international matrix-solver prediction system on a French-Japanese international grid computing environment

Suzuki, Yoshio; Kushida, Noriyuki; Tatekawa, Takayuki; Teshima, Naoya; Caniou, Y.*; Guivarch, R.*; Dayde, M.*; Ramet, P.*

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 6 Pages, 2010/10

The "Research and Development of International Matrix-Solver Prediction System (REDIMPS)" project, which is founded by the Strategic Japanese-French Cooperative Program on "Information and Communications Technology including Computer Science" with CNRS and JST, aims at improving the "Test for Large System of Equations (TLSE)" sparse linear algebra expert system by establishing an international grid computing environment between Japan and France. Here, we have established the interoperable environment between French and Japanese grid middleware (DIET and AEGIS), and have confirmed that TLSE can rely on this French and Japanese interoperable environment for researchers to select a matrix-solver suitable to their each application program. By this study, we proposed to the French and Japanese researchers the environment in which they can obtain useful information for the improvement of their application program.

Elastic-plastic connection model describing dynamic interactions of component connections

Nishida, Akemi; Araya, Fumimasa; Kushida, Noriyuki; Kondo, Makoto; Sakai, Michiya*; Shiogama, Yuzo*

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 6 Pages, 2010/10

The objective of this research is to contribute to the seismic design evaluation of nuclear facilities through the construction of a numerical evaluation system which is able to evaluate both global and local behaviors of facilities under severe seismic events. As one of the technology components to realize this objective, we are developing a physical model describing the dynamic interaction characteristics of component connections, called as the elastic-plastic connection model. We focused on the joints of the support structures of the component and the building in nuclear plants which generally designed as fixed/pinned boundaries, and tried to consider their dynamic interaction effects. In this paper, we show the proposal of the elastic-plastic connection model and the application of the model to a numerical simulation using a real plant data. The precision of the model was optimized by adjusting its parameters using the data obtained in the experiment.

Evaluation of local stress and local hydrogen concentration at grain boundary using three-dimensional polycrystalline model

Ebihara, Kenichi; Itakura, Mitsuhiro; Yamaguchi, Masatake; Kaburaki, Hideo; Suzudo, Tomoaki

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 6 Pages, 2010/10

The decohesion model in which hydrogen segregating at grain boundaries reduces their strength is considered to explain hydrogen embrittlement of steels. Therefore in order to understand hydrogen embrittlement from this model, stress and hydrogen concentration at grain boundaries need be evaluated under the fracture condition for tensile test specimens. From this consideration, we evaluated the stress and the hydrogen concentration at grain boundaries in the three-dimensional polycrystalline model which was generated by Voronoi tessellation. The different crystallographic orientation was given to each grain. Extracted data from the calculation in the notched round-bar specimen model under the tensile test condition was given to the polycrystalline model as the boundary condition. As a result, it was found that the valuated stress does not reach the fracture stress which was estimated under the condition of the evaluated hydrogen concentration by first principles calculation.

Chemical states of fission products and actinides in irradiated oxide fuels analyzed by thermodynamic calculation and post-irradiation examination

Kurosaki, Ken*; Tanaka, Kosuke; Osaka, Masahiko; Oishi, Yuji*; Muta, Hiroaki*; Uno, Masayoshi*; Yamanaka, Shinsuke*

Proceedings of Joint International Conference of 7th Supercomputing in Nuclear Application and 3rd Monte Carlo (SNA + MC 2010) (USB Flash Drive), 4 Pages, 2010/10

It is important to understand the behavior of fission products and actinides under irradiation. In the present study, the chemical states of fission products and actinides in irradiated oxide fuels were evaluated by both thermodynamic equilibrium calculation and post-irradiation examination.