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Mitsui, Seiichiro
Kinzoku, 93(3), p.211 - 218, 2023/03
As part of research and development of geological disposal, "natural analogues" have been applied to validate concept of models and evaluation methodologies for performance assessment. By introducing our research results on natural analogues, this paper presents how we have utilized knowledge of excavated archaeological artifacts for geological disposal studies.
Yanagida, Akinobu*; Ura, Yoko*; Mitsui, Seiichiro; Ishidera, Takamitsu; Kawakita, Ryohei
Nara Bunkazai Kenkyujo Soritsu 70-Shunen Kinen Rombunshu; Bunkazai Ronso 5, p.843 - 856, 2023/03
To investigate chloride salt accumulation inside an iron artifact in soil, non-destructive analysis of three iron artifacts excavated from the Heijo Palace Site was conducted using elemental mapping by X-ray fluorescence analysis, micro-X-ray diffraction analysis, and X-ray computed tomography. Furthermore, the buried environments of the artifacts were presumed based on the previous reports of the environmental investigation at the Heijo Palace site. The results revealed the iron artifact's corrosion behavior was different individually- (1) the iron artifact that was presumed buried under oxidation environments had a goethite/magnetite corrosion layer and contained akageneite inside the corrosion layer. (2) the metal of the other iron artifacts buried under the oxidation environment had eluted absolutely and the artifacts had a rust layer formed by only goethite. (3) the other artifact buried in reduction environments had a rust layer composed of siderite. Accumulation of chloride salts inside an iron artifact was observed only in (1). Because each Cl
concentration measured in underground water observation holes at the Heijo Palace Site showed almost the same level concentrations, it was presumed that the accumulation of chloride salts depended on the environmental factor except for Cl concentration. Based on these results, there was a possibility that the occurrence of local corrosion attributed to the separation of anodic and cathodic regions through the formation of the goethite/magnetite rust layer caused chloride salts accumulation inside an iron artifact.
Kokubu, Yoko; Nishio, Tomohiro; Fujita, Natsuko; Matsubara, Akihiro
Proceedings of the 8th East Asia Accelerator Mass Spectrometry Symposium and the 22nd Japan Accelerator Mass Spectrometry symposium (EA-AMS 8 & JAMS-22), p.91 - 93, 2020/00
no abstracts in English
Mitsui, Seiichiro
Koeki Zaidan Hojin Tottoriken Kyoiku Bunka Zaidanhen 2014 "Yoshida Nakamichi Iseki" Tottoriken Kyoiku Iinkai, p.221 - 230, 2015/03
An ancient socketed iron axe was excavated from Yoshida Nakamichi site in Tottori City, Tottori Prefecture. To understand reasons of corrosion state of the axe, we studied relationship between burial environment and corrosion. As environmental conditions, we investigated groundwater chemistry and corrosion rate with iron probe monitor, etc. As for corrosion state, we analysed corrosion depths with a X-ray CT and corrosion products with a portable XRD/XRF. As results, we found that the redox potential and dissolved oxygen level as environmental conditions were very low, and that the maximum corrosion rate (2
10
mm/y) evaluated from measured corrosion depths was smaller than the probe corrosion rate (510
mm/y) by two orders of magnitude and identified siderite (FeCO
) as a corrosion product. The results suggested that the siderite precipitated on the surface of the iron sword inhibited corrosion reaction.
Mitsui, Seiichiro
Mukibanda Iseki Hakkutsu Chosa Kenkyu Nempo 2014, p.27 - 44, 2015/03
A number of ancient iron artifacts were excavated from Mukibanda archaeological remains in Tottori Prefecture. To obtain detailed information on corrosion state of the iron artifacts, we analysed corrosion depths with a X-ray Computer Tomography (X-ray CT) and corrosion products with a portable X-ray diffractometer equipped with X-ray fluorescence spectrometer (XRD/XRF). As reference information for relationship between corrosion and environmental conditions, we also measured some environmental parameters. As results, we found that the maximum corrosion rates evaluated from measured corrosion depths was smaller than the probe corrosion rate by one to two orders of magnitude. The results suggested that the corrosion products precipitated on the surface of the iron artifacts inhibited corrosion reaction.
Mitsui, Seiichiro
Ippan Zaidan Hojin Yonagoshi Bunkazaidan Maizo Bunkazai Hakkutsu Chosa Hokokusho, 6; Ippan Kokudo 180-Go (Nambu Baipasu) Doro Kairyo Koji Ni Tomonau Maizo Bunkazai Hakkutsu Chosa Hokokusho V; Tottoriken Saihakugun Nambucho; Sakaiyaishi Iseki, 2, p.35 - 48, 2015/00
A number of ancient iron artifacts in apparently well-preserved state were excavated from Sakai-Yaishi archaeological site in Nambu Town, Tottori Prefecture. To obtain detailed information on corrosion state of the iron artifacts, we analysed corrosion depths with a X-ray Computer Tomography (X-ray CT) and corrosion products with a portable X-ray diffractometer equipped with X-ray fluorescence spectrometer (XRD/XRF). For comparison, a poor-preserved iron artifact excavated from Bakurou-Machi archaeological site in Bakurou Town also analysed. The results imply that the difference in the corrosion states of the iron artifacts between Sakai-Yaishi and Bakurou-Machi archaeological sites reflects a difference in locations between both archaeological sites, that is a difference in burial environmental conditions between a hillside and a beachside.
Honda, Takashi*; *
JNC TJ8400 2000-007, 200 Pages, 2000/02
JNC-TJ8400-2000-007.pdf:14.84MB
In general, it is very difficult to evaluate the residual state of metallic iron and the original shape of iron-base archaeological artifacts, as these are covered by thick oxide films formed in the ground during over several hundred years. The purpose of this research is to quantify the corrosion of an artifact such as base, knife, and nail, which was digged out of the relics about 500-1,000 years old. (1)The outer oxide film layer and the inner metallic iron can be quantitatively divided by using X-ray CT method. Furthermore, the original surfaces of artifacts can be estimated from the obtained images, even if the metallic iron has corroded completely. The X-ray CT images were also compared with those obtained by X-ray transmission inspection. (2)The corrosion amounts and rates were evaluated on the basis of thicknesses, densities, and iron concentrations of oxide films. (3)The characteristic differences between ancient iron and modern carbon steel were evaluated by analyzing the ancient iron slag.
Umezawa, Hirokazu
Nihon Genshiryoku Gakkai-Shi, 32(7), p.658 - 660, 1990/07
no abstracts in English
Mitsui, Seiichiro
no journal, ,
Carbon steel, copper and titanium are considered as candidate materials for a metallic container (overpack) for the geological disposal of high-level radioactive wastes in Japan. Among these candidate materials, carbon steel and copper are commonly found as either iron or bronze artifacts at archaeological sites, and so have been used as "archaeological analogues" to understand the long-term corrosion behavior of overpack materials under geological disposal conditions. This presentation summarizes some recent archaeological analogue studies conducted at JAEA.
Mitsui, Seiichiro; Ishidera, Takamitsu; Hisa, Yoichiro*
no journal, ,
Though useful information such as estimation of the burial environment is thought to be recorded in the layer structure of the corrosion product from the soil consolidation layer to near metallic iron from the viewpoint of conservation science, the soil consolidation layer on the surface of the iron artifact is usually removed in the process of the conservation treatment, because the original shape of the iron artifact is the main subject for archaeological studies. Furthermore, since the iron artifact is precious cultural treasure, the analysis is typically carried out only with non-destructive methods such as transmission X-ray observation and X-ray CT analysis. In such circumstances, it is often difficult to understand the layer structure of the corrosion product. In this study, CT value distributions of three iron nail artifacts excavated from Hakata ruins in Fukuoka City, Fukuoka Prefecture, were obtained by X-ray CT analysis of the bulk samples, and the cross section sample from one of the artifacts was analyzed with micro Raman spectroscopy to understand the layer structure of the corrosion product. On the basis of the comparison result of CT value distribution and layer structure of the corrosion product, the layer structure of the corrosion product was estimated from CT value distribution on two artifacts without cross section sample.
