Neutron capture and total cross-section measurements and resonance parameter analysis of niobium-93 below 400 eV

Endo, Shunsuke; Kimura, Atsushi; Nakamura, Shoji; Iwamoto, Osamu; Iwamoto, Nobuyuki; Rovira Leveroni, G.; Terada, Kazushi*; Meigo, Shinichiro; Toh, Yosuke; Segawa, Mariko; et al.

Journal of Nuclear Science and Technology, 59(3), p.318 - 333, 2022/03

https://doi.org/10.1080/00223131.2021.1970040

Development on computer system of the coupled thermo-hydro-mechanical and chemical process in the near-field of the high-level radioactive waste repository

Fujita, Tomoo; Fujisaki, Kiyoshi; Suzuki, Hideaki*; Kawakami, Susumu; Yui, Mikazu; Chijimatsu, Masakazu*; Neyama, Atsushi*; Ishihara, Yoshinao*; Hishiya, Tomoyuki*

Proceedings of 2nd International Conference on Coupled T-H-M-C Processes in Geo-systems; Fundamentals, Modeling, Experiments and Applications (GeoProc 2006), p.416 - 421, 2006/00

We have initiated a research on the coupled Thermo-Hydro-Mechanical-Chemical (THMC) processes and are trying to carry out numerical experiments on the coupled THMC processes in order to predict the near-field long-term evolution. This paper describes the modified THMC model to add on the function of de-gases and gases diffusion, accumulation and dilution phenomena for mass transport analysis, and of ionic exchange, surface reaction and kinetic reaction for geochemical analysis. And also the results of demonstration study with THMC code are shown.

Study on Radiation Dose from Vitrified Waste

WAKASUGI, Keiichiro; Miyahara, Kaname; Makino, Hitoshi; Ishiguro, Katsuhiko; Sawamura, Hidenori*; Neyama, Atsushi*; Nishimura, Kazuya*

JNC TN8400 2003-022, 84 Pages, 2003/11

JNC-TN8400-2003-022.pdf:9.58MB

The radiation dose from the vitrified waste which is the same specification set in the Reference Case of the second progress report (H12 report) was evaluated quantitatively taking into account of the shield of the canister and the overpack. In order to understand the feature of radiation dose from the vitrified waste in terms of shielding, the thickness of the concrete shield to decrease less than safety standard for a radiation controlled zone was evaluated. Main results are summarized as follows. (1)The effective dose rates in the case considering the vitrified waste and the canister decrease approximate 45 orders of magnitude during the period of 1,000 years after vitrification due to decay of short half-life radionuclides. The effective dose rate doesn't decrease from 1,000 to 10,000 years. (2)The effective dose rates at the outside of overpack in the case considering the vitrified waste, canister and overpack are smaller than those inside of overpack approximate 5 orders of magnitude during the period of 100 years due to shielding effect of the overpack. However this difference is relatively small after 100 years since the contribution of radiation to total effective dose rates decrease due to decay of fission products. (3)Excepting a few cases, the result using the old law (dose equivalent rate) is larger than the result using the new law (effective dose rate). However the difference between these results is less than factor of 1.2. (4)The thickness of the concrete shield required to attenuate the effective dose during the period of 50 years less than safety standard for a radiation controlled zone is calculated as approximate 0.8m1.5m. The important factors to determine the thickness of the concrete shield are the radiation in the case of vitrified waste and the canister, and the neutron radiation in the case of vitrified waste, canister and overpack.

Investigation Research on the Evaluation of a Coupled Thermo-Hydro-Mechanical-Chemical Phenomena (II); Outline Report

Ishihara, Yoshinao*; Chijimatsu, Masakazu*; Neyama, Atsushi*; Tanaka, Yumiko*; Amemiya, Kiyoshi*; Shiozaki, Isao*; Ito, Takaya*

JNC TJ8400 2003-033, 118 Pages, 2003/02

JNC-TJ8400-2003-033.pdf:1.66MB

In order to realize a coupling analysis in the near field of the geological disposal system, the coupling analysis code on the thermo-hydro-mechanical-chemical phenomena by THAMES, Dtransu and phreeqe60, which are existing analysis code, is developed in this study. And we carried out the case analysis on the thermo-hydro-mechanical-chemical phenomena by this code.

None

Ishihara, Yoshinao*; *; *; Neyama, Atsushi*; *; *

JNC TJ8440 2002-009, 179 Pages, 2002/03

JNC-TJ8440-2002-009.pdf:3.03MB

no abstracts in English

Investigation research on the evaluation of a coupled thermo-hydro-mechanical-chemical phenomena; outline report

Chijimatsu, Masakazu*; Neyama, Atsushi*; Ishihara, Yoshinao*; Amemiya, Kiyoshi*; *; Iwata, Hiroshi*; Sagawa, Hiroshi*

JNC TJ8400 2002-004, 83 Pages, 2002/02

JNC-TJ8400-2002-004.pdf:0.91MB

In order to realize a coupling analysis in the near field of the geological disposal system, this study has been studied on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and preliminary coupling analysis by using development environmental tool (Diffpack) for numerical analysis. (1) In order to prepare the strategy on the addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES), we have studied on the requirement of THAMES-Transport and methodology of coupling analysis. After that we set out modification plan by the Eulerian-Lagrangian (EL) method. (2) Based on the document of modification plan, we have done addition of the mass transport model to the coupled thermo-hydro-mechanical analysis code (THAMES) and carried out verification analysis in order to confirm on the accuracy of THAMES-Transport. (3) In order to understand on the behavior of NaCl in the porewater under the coupled thermo-hydro-mechanical phenomena in the HLW engineered barrier system, we have calculated coupling phenomenon by using THAMES-Transport. Transportation and concentration phenomena of NaCl are calculated but precipitation of NaCl is not occurred under the analysis conditions in this report. (4) In order to confirm about feasibility of coupling analysis under the development environmental tool (Diffpack) for numerical analysis, we have carried out on the design work and writing program of the preliminary coupling system. In this study, we have adopted existing transport model (HYDROGEOCHEM) and geochemical model (phreeqe60) for preliminary coupling system. (5) In order to confirm program correctness of preliminary coupling system, we have carried out benchmarking analysis by using existing reactive-transport analysiscode (HYDROGEOCHEM). (6)We have been prepared short-range development plan based on through the modification study of THAMES and writing program of the preliminary coupling ...

Investigation research of core-basic information associated with the coupling analysis; Outline report

Kataoka, Shinichi*; Kawahara, Kenichi*; Matsunaga, Kenichi*; Ishihara, Yoshinao*; Neyama, Atsushi*; Nakagawa, Koichi*; Iwata, Hiroshi*; Mori, Koji*

JNC TJ8400 2001-037, 33 Pages, 2001/03

JNC-TJ8400-2001-037.pdf:2.02MB

no abstracts in English

Development of the evaluation methodology for earthquake resistance of the engineered barrier system (III)

Mori, Koji*; Neyama, Atsushi*; Nakagawa, Koichi*

JNC TJ8400 2000-064, 175 Pages, 2000/03

JNC-TJ8400-2000-064.pdf:5.23MB

In this study, the following tasks have been performed in order to evaluate the stability of earthquake resistance for the engineered barrier system(EBS) of High Level Waste (HLW) geological isolation system. (1)validation studies for the liquefaction model. The function of single-phase analysis without interaction between soil and pore water in three-dimensional effective stress analysis code, which had been developed in this study, have been verified using by actual vibration test data. This fiscal year, some validation studies for the function of liquefaction analysis was conducted usig by actual measured data through the laboratory liquefaction test. (2)Supplemental Studies for JNC Second Progress Report. Through the JNC second progress report, it was considered that the stability of earthquake resistance of the engineered barrier system would be maintained under the major seismic event. At the same time we have recognized that several model parameters for joint-crack element, which takes into account for the response behavior of material discontinuous surface such as between overpack and buffer material, will become important in the response behavior of the whole EBS. This year, we have studied about several topics, which arise from technical discussion on JNC second progress report and we have discussed about total seismic stability of EBS. (3)Supplemental Studies for joint study with NRIDP. At this fiscal year, the joint study with National Research Institute for Disaster Prevention (NRIDP) will be final stage. UP to this day, incremental validation studies had been continued using by mesuared data obtained from vibration test. In this final stage, validation analysis has been conducted again using by current version new analysis code and maintained the validation data which will be contribute to the joint study mentioned above.

Development of Thermodynamic Databases for Geochemical Calculations

Oda, Chie; Arthur, R. C,*; Sasamoto, Hiroshi; Shibata, Masahiro; Yui, Mikazu; Neyama, Atsushi*

JNC TN8400 99-079, 287 Pages, 1999/09

JNC-TN8400-99-079.pdf:9.78MB

Two thermodynamic databases for geochemical calculations supporting research and development on geological disposal concepts for high level radioactive waste are described in this report. One, SPRONS.JNC, is compatible with thermodynamic relations comprising the SUPCRT model and software, which permits calculation of the standard molal and partial molal thermodynamic properties of minerals, gases, aqueous species and reactions from 1 to 5000 bars and 0 to 1000C. This database includes standard molal Gibbs free energies and enthalpies of formation, standard molal entropies and volumes, and Maier-Kelly heat capacity coefficients at the reference pressure (1 bar) and temperature (25C) for 195 minerals and 16 gases. It also includes standard partial molal Gibbs free energies and enthalpies of formation, standard partial molal entropies, and Helgeson, Kirkham and Flowers (HKF) equation-of-state coefficients at the reference pressure and temperature for 1147 inorganic and organic aqueous ions and complexes. SPRONS.JNC extends similar databases described elsewhere by incorporating new and revised data published in the peer-reviewed literature since 1991. The other database, PHREEQE.JNC, is compatible with the PHREEQE series of geochemical modeling codes. It includes equilibrium constants at 25C and 1 bar for mineral-dissolution, gas-solubility, aqueous-association and oxidation-reduction reactions. Reaction enthalpies, or coefficients in an empirical log K(T) function, are also included in this database, which permits calculation of equilibrium constants between 0 and 100C at 1 bar. All equilibrium constants, reaction enthalpies, and logK(T) coefficients in PHREEQE.JNC are calculated usig SUPCRT and SPRONS.JNC, which ensures that these two databases are mutually consistent. They are also internally consistent insofar as all the data are compatible with basic thermodynamic definitions and functional relations in the SUPCRT ...

Development of the evaluation methodology for earthquake resistance of the engineered barrier system, II

Mori, Koji*; Neyama, Atsushi*; Shirakawa, Toshihiko*

JNC TJ8400 99-079, 32 Pages, 1999/02

JNC-TJ8400-99-079.pdf:3.51MB

In this study, the following several tasks have been performed in order to evaluate the stability of earthquake resistance for the engineered barrier system of High Level Waste(HLW) geological isolation system. (1)Based on the wave propagation theory for one-dimensional multl-layer system, we have estimated the underground seismic wave that propagates in the HLW repository site. This analysis was based upon the JNC Virtual Geological Model and we used the El-Centro earthquake data as the surface observed wave. Through this inversion analysis, we have found that this interest geological model has the about 60%(G.L.-1000m) and 20%(G.L.-500m) decreasing ratio of the acceleration to the surface observed acceleration level. (2)Since 1992 we have developed the three dimensional seismic response analysis code for the engineered barrier system, which based on Finite Element Methodology. This analysis code has various function to take into consideration the realistic repository system(e.g.material nonlinear models, joint crack element and infinite viscous boundary element). We have made the study of the concrete analysis method designed to the near field seismic response analysis, through the sensitivity analysis using above various function. Based on these studies, we have evaluated the earthquake resistance stability for the near-field repository system. Two types of disposal concept were considered as the reference case associated with the JNC second progress report. Through this study, we have concluded that the shear stress due to earthquake in the buffer material is very small relative to that due to the earth load and the earthquake resistance stability will be maintained.