Effects of helium on irradiation response of reduced-activation ferritic-martensitic steels; Using nickel isotopes to simulate fusion neutron response

Kim, B. K.*; Tan, L.*; Sakasegawa, Hideo; Parish, C. M.*; Zhong, W.*; Tanigawa, Hiroyasu*; Kato, Yutai*

Journal of Nuclear Materials, 545, p.152634_1 - 152634_12, 2021/03

https://doi.org/10.1016/j.jnucmat.2020.152634

Hydrogen behavior in primary precipitate of F82H steel; Atomistic calculation based on the density functional theory

Watanabe, Yoshiyuki; Iwakiri, Hirotomo*; Murayoshi, Norihiko*; Kato, Daiji*; Tanigawa, Hiroyasu

Plasma and Fusion Research (Internet), 10, p.1205086_1 - 1205086_2, 2015/12

https://doi.org/10.1585/pfr.10.1205086

In this paper, formation energy of isolated hydrogen atom in CrC has been theoretically investigated with atomistic calculation based on the density functional theory. The lowest calculated formation energy of a hydrogen atom is -0.48 eV with a trigonal bipyramidal configuration surrounded by five regular Cr lattice atoms. A comparison of the formation energy of hydrogen atom in bcc-iron may indicate that hydrogen atoms in F82H steel are more energetically favorable in CrC-based precipitate rather than Fe-based matrix, leading to an increase of the tritium retention in the precipitate.

Reduction of contaminated concrete waste by recycling aggregate with the aid of pulsed power discharge

Arifi, E.*; Ishimatsu, Koichi*; Iizasa, Shinya*; Namihira, Takao*; Sakamoto, Hiroyuki*; Tachi, Yukio; Kato, Hiroyasu*; Shigeishi, Mitsuhiro*

Construction and Building Materials, 67(Part B), p.192 - 196, 2014/09

https://doi.org/10.1016/j.conbuildmat.2014.06.001

The Fukushima Dai-ichi Nuclear Plant accident has resulted in a large amount of radioactively contaminated concrete. The possible application of the pulsed power discharge to reduce the amount of contaminated concrete as radioactive waste was investigated. The contaminated concrete was decontaminated by separating contaminated matrix from uncontaminated coarse aggregate under pulsed power discharge process. In this study, a stable Cs isotope was used to simulate radioactively contaminated concrete. As a result, while the volume of reclaimed aggregate from contaminated concrete could be reproduced was up to 60%, nevertheless Cs detected in the reclaimed aggregate was only approximately 3%. Thus most of the Cs were dissolved in water during the discharge process. It is expected that the pulsed power could reduce the contaminated concrete waste by reusing aggregate. Further investigations are requested to test the applicability of this method under the realistic conditions close to the actual waste.

Measurement of sorption, diffusion and pore physicality for granite sample

Kunimaru, Takanori; Morikawa, Keita; Tachi, Yukio; Kuno, Yoshio*; Hosoya, Shinichi*; Shimoda, Satoko*; Kato, Hiroyasu*; Nakazawa, Toshiyuki*; Ikuse, Hiroyuki*; Kubota, Masako*

JAEA-Data/Code 2012-013, 96 Pages, 2012/07

JAEA-Data-Code-2012-013.pdf:7.41MB
JAEA-Data-Code-2012-013(errata).pdf:0.13MB

For the purpose to understand the relationship between characteristic of mass transport and characteristic of fracture, the following experiments were carried out using core sample, which was sampled from the -300 m Stage. This paper compiled the results of these experiment. (1) Diffusion experiments of Cs, Sr, I and uranin in granite samples (2) Sorption experiments of Cs and Sr on crushed granite (3) Measurement of pore physicality by Mercury Intrusion and water saturation

Effect of heat treatments on tensile properties of F82H steel irradiated by neutrons

Wakai, Eiichi; Ando, Masami; Sawai, Tomotsugu; Tanigawa, Hiroyasu; Taguchi, Tomitsugu; Stroller, R. E.*; Yamamoto, Toshio; Kato, Yoshiaki; Takada, Fumiki

Journal of Nuclear Materials, 367-370(1), p.74 - 80, 2007/08

https://doi.org/10.1016/j.jnucmat.2007.03.164

no abstracts in English

Microstructural analysis of mechanically tested reduced activation ferritc/martensitic steels

Tanigawa, Hiroyasu; Hirose, Takanori; Ando, Masami; Jitsukawa, Shiro; Kato, Yudai*; Koyama, Akira*

Journal of Nuclear Materials, 307-311(Part1), p.293 - 298, 2002/12

https://doi.org/10.1016/S0022-3115(02)01002-4

It has been a key issue to get the mechanical understanding of fracture process on microstructure basis, especially on neutron-irradiated materials, but not yet to be understood well enough as for the difficulty of making transmission electron microscope (TEM) thin film sample from mechanical-tested specimen. To solve this technical problem, the focused ion beam (FIB) micro-sampling system was installed to the Research Hot Laboratory of Japan Atomic Research Institute (JAERI), Japan. This system makes it possible to fabricate the TEM specimens from the critical points of mechanical-tested radioactive specimens, such as the crack initiation points of fatigue fracture on neutron irradiated specimen. In this paper, the microstructure of mechanical-tested specimen of Reduced Activation Ferritic/martensitic steels, RAFs are investigated focusing on the helium effects to fatigue fracture.

Response of reduced activation ferritic steels to high-fluence ion-irradiation

Tanigawa, Hiroyasu; Ando, Masami; Kato, Yudai*; Hirose, Takanori*; Sakasegawa, Hideo*; Jitsukawa, Shiro; Koyama, Akira*; Iwai, Takeo*

Journal of Nuclear Materials, 297(3), p.279 - 284, 2001/09

https://doi.org/10.1016/S0022-3115(01)00633-X

no abstracts in English

Study on solubility and leaching property of Iodine-129 waste-forms for geological disposal

Yanagisawa, Ichiro*; Katsurai, Kiyomichi*; Izumi, Jun*; Saigusa, Moriyuki*; *; *; *; Ueta, Shinzo*

JNC TJ8400 2000-038, 202 Pages, 2000/02

JNC-TJ8400-2000-038.pdf:15.12MB

(1)Sodalite and tourmaline are natural-occurring minerals, which can contain halide in their aluminosilicate lattices. Therefore, these materials have possibilities of immobilization of I-129. In this study, solubility measurements for these materials were carried out. It was confirmed from dissolution behaviors obtained for some kinds of sodalite and calculated results of solubilities based on thermodynamic data that dissolution of sodalite to aqueous solution could be limited by its solubility. Solubility of sodalite had tendencies of "synthesized one natural one" and "chloride iodide". Immobilized iodine in sodalite crystalline lattice was not replaced by chlolide ion in the solution. It was indicated that tourmaline has a possibility as a waste material containing I-129 from comparison of dissolution behavior of element with sodalite. (2)Leaching property of a multi-layered waste-form, that is composed of (1)iodine bearing material (zeolite), (2)coating layer (silica and apatite) and 3)low solubility matirx (apatite), was studied under reducing condition. The following results were obtained by the leaching experiments: (1)The coating layer of hidroxyapatite can reduce the iodine leaching rate by 4 order compared with that of bare iodine bearing material. (2)Ca and P concentration after one-month dipping reached the solubility estimated by the theoretical calculation using PHREEQE code. As a conclusion, it was indicated that this waste-form concept has potential to show low leaching rate.

Certification of reliability of nuclide migration data

Ueta, Shinzo*; *; *; *

JNC TJ8400 2000-002, 364 Pages, 2000/02

JNC-TJ8400-2000-002.pdf:16.99MB

Japan Nuclear Cycle Development Institute (JNC) have been setting migration parameters and developing its database for the 2nd Progress Report of HLW Geological Disposal (H12 Report). In this study, experimentswere carried out to certify the reliability of parameters and scenario, and examination was carried out to survey procedures of quality management. The main contents are as follows. (1)Data acquisition for certification of migration parameters. The effect of NH complex of Pd on distribution coefficients (Kd) of Pd on both bentonite and rocks, and the effect of sulfate and carbonate complexes of Am on Kds of Am on bentonite are investigated. Kds of Pd depended on NH concentration in aqueous. The dependence varied with pH. Effects of sulfate and carbonate complexes on Kds of Am were not remarkable. Apparent diffusivities of Cs in bentonite saturated by saline water were measured. It was confirmed that the apparent diffusivities of Cs in saline water were similar to those in pure water. (2)Evaluation of colloidal effect on nuclide migration. An evaluation of validity of analytical model (Hwang's model) for nuclide migration under existence of colloids and investigation of characterization of colloids in groundwater were carried out. As the results, it was indicated that the Hwang's model was appropriate, and it was found that samplingtechnique influenced concentration and size distribution of colloids. (3)Influence of organic substances on solubility. Solubility of Th was measured under the condition with humic acid and carbonate. It increased roughly in proportion to the concentration of humic acid. And it was remarkably high under the condition with carbonate. It was confirmed that Th solubility data set in H12 report was conservative, even though humic acid existed in groundwater. (4)Use of Mechanistic Models for Safety Assessment. The integrated sorption/diffusion model has been used to calculate K, D and D values ...

Effective diffusion coefficients of HTO, Cs, I and C in compacted Ca-bentonite

Mihara, Morihiro; ; Ueta, Shinzo*; *

JNC TN8430 99-011, 27 Pages, 1999/11

JNC-TN8430-99-011.pdf:2.25MB

In radioactive waste disposal, compacted Na-bentonite has been proposed for a buffer material. However, Na-bentonite would change to Ca-bentonite in the long term period. The change of Na-bentonite to Ca-bentonite might cause the change in the data concerning with nuclides migration properties such as permeability, sorption and diffusion. In this study, effective diffusion coefficients of HTO, Cs, I and C in compacted Ca-bentonite which was changed from Na-bentonite, Kunigel V1, were obtained and were compared to published those of Kunigel V1. In addition, effective diffusion coefficients for compacted Ca-bentonite with syncetic sea system water, SW, were obtained in order to investigate effect of solution composition. The magnitude of effective diffusion coefficients in Ca-bentonite are arranged in smaller order as CsHTOIC. It is estimated that their effective diffusion coefficients are same those of Na-bentonite. About effect of solution composition, effective diffusion coefficients of HTO in 1.8g/cm dry density with SW were almost same values with distilled system water, DW. However, effective diffusion coefficients of HTO in lower density were smaller than values with DW. Regarding as effective diffusion coefficients of Cs in 1.8g/cm dry density, the effect of SW could not be observed as well as HTO. However, effective diffusion coefficients of I and C existing as an anion in pore water of bentonite increased by the reduction in the ion exclusion.