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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.
Yamauchi, Michinori*; Takemura, Morio*; Nakamura, Hiroo; Fischer, U.*; Ida, Mizuho*; Mori, Seiji*; Sato, Satoshi; Nishitani, Takeo; Simakov, S. P.*; Sugimoto, Masayoshi
Fusion Science and Technology, 47(4), p.1008 - 1011, 2005/05
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)no abstracts in English
Ohashi, Hiroshi*; Sato, Seichi*; Kozaki, Tamotsu*
JAERI-Tech 2002-021, 52 Pages, 2002/03
JAERI-Tech-2002-021.pdf:2.95MB
no abstracts in English
Taniguchi, Naoki; ; Kawasaki, Manabu*; Masugata, Tsuyoshi*
JNC TN8400 2001-001, 56 Pages, 2000/12
JNC-TN8400-2001-001.pdf:2.05MB
It is necessary to clear the effects of corrosion products on the corrosion life time of carbon steel overpack for geological isolation of high-level radioactive waste(HLW). Especially, it is important to understand the effects of magnetite because magnetite as a simulated corrosion product is reported to accelerate the corrosion rate of carbon steel. In this study, corrosion tests to reproduce the acceleration of corrosion due to magnetite was performed and the mechanism of the acceleration was investigated to evaluate the effects of magnetite as a corrosion product. Based on the results of experiments, following conclusions are obtained ; (1)Magnetite powder accelerates the corrosion rate of carbon steel. The main reaction of corrosion under the presence of magnetite is the reduction of Fe(III) in magnetite to Fe(II), but the reaction of hydrogen generation is also accelerated. The contribution of hydrogen generation reaction was estimated to be about 30% in the total corrosion reaction based on the experimental result of immersion test under the presence of magnetite. (2)Actual corrosion products containing magnetite generated by the corrosion of carbon steel protect the metal from the propagation of corrosion. The corrosion depth of carbon steel overpack due to magnetite was estimated to be about 1 mm based on the results of experiments. Even if the effect of magnetite is taken into the assessment of corrosion lifetime of overpack, total corrosion depth in 1000 years is estimated to be 33 mm, which is smaller than the corrosion allowance of 40 mm described in the second progress report on research and development for the geological disposal of HLM/ in Japan. It was concluded that the effect of magnetite on the corrosion life time of carbon steel overpack is negligible.
; ; Shimizu, Kazuhiko; Miyahara, Kaname; ; Seo, Toshihiro; Fujita, Tomoo
JNC TN1410 2000-008, 100 Pages, 2000/10
JNC-TN1410-2000-008.pdf:4.23MB
no abstracts in English
Odano, Naoteru; Ishida, Toshihisa
Journal of Nuclear Science and Technology, 37(Suppl.1), p.584 - 588, 2000/03
no abstracts in English
Shibata, Toshio*; *; *; Tsuru, Toru*; Inoue, Hiroyuki*
JNC TJ8400 2000-013, 38 Pages, 2000/02
JNC-TJ8400-2000-013.pdf:3.25MB
None
Saito, Junichi; Tachi, Yoshiaki; ; Kano, Shigeki
PNC TN9410 98-082, 60 Pages, 1998/08
Ceramics possessing high temperature strength are promising matelials for the structural application in severe environment. The development of ceramics has been carried out in order to use them in FBR environment such as liquid sodium. In particular, corrosion behavior of ceramics has been investigated to improve the corrosion resistance in liquid sodium. However, the corrosion mechanism of ceramics was not comprehended in detail even now. Because corrosion products which were deposited on the surface of test pieces a during corrosion test and played an important role in corrosion behavior were not detected distinctly after the corrosion test. In this study, an ion implantation technique was applied to understand the corrosion mechanism of ceramics in the stead of the conventional corrosion test. Sodium ions were implanted in ceramics (100keV, 1.910
ions/cm
) and then heat treatment was performed at either 923K or 823K for 36ks in argon atmosphere. After that, products on the surface were analyzed using SEM and TEM observation and X-ray diffraction. Consequently, a kind of the corrosion product was not identified exactly, but the presence of corrosion products was confirmed on the surface. It caused by the amount of corrosion products was only a few. In future, it is necessary to carry systematically out the implantation and heat treatment under various conditions. Therefore, it seems that the beneficial information will be obtained to understand the corrosion mechanism of ceramics.
Saito, Junichi; Morinaga, Masahiko*; Kano, Shigeki
PNC TN9410 98-072, 97 Pages, 1998/07
Research on structural materials which will be utilized even in the severe environment of high-temperature liquid alkali metals has been promoted in order to develop the frontiers of materials techniques. The super-heat resisting alloys which are based on refractory metals, Nb and Mo, are aimed as promising materials used in such an environment. The corrosion resistance in liquid Li and the mechanical properties such as creep and tensile strengths at high temperatures are important for these structural materials. On the basis of many expeliments and analyses of these properties at 1473K, the material design of Nb-based and Mo-based alloys has-been carried out successfully. In this report, all the previous experimental results of corrosion tests in liquid Li were summarized systematically for Nb-based and Mo-based alloys. The corrosion mechanism was proposed on the basis of a series of analyses, in particular, focussing on the deposition mechanism of corrosion products on the surface and also on the initiation and growth mechanism of cracks on the corroded surface of Nb-based alloys. The principal results are as follows. (1)For the deposition mechanism, a reaction took place first between dissolved metallic elements and nitrogen which existed as an impurity in liquid Li and then corrosion products (nitrides) precipitated on the metal surface. Subsequently, another reaction took place between dissolved metalic elements in liquid Li, and corrosion products (intermetallic compounds) precipitated on the metal surface. The composition of deposited corrosion products could be predicted on the basis of the deposition mechanism. (2)For the crack initiation mechanism, the chemical potential diagrams were utilized in order to understand the formation of Li-M-O ternary oxides which caused cracks to be formed on the corroded surface. Consequently, it was evident that not only the concentration of the dissolved oxygen in the alloy but also the concentration of Li which ...
Tsujikawa, Shigeo*; *; *; Tsuru, Toru*; Shibata, Toshio*; *
PNC TJ1560 98-001, 164 Pages, 1998/02
None
Shimogori, Kazutoshi*; Tomari, Haruo*; *; Fujiwara, Kazuo*; Masugata, Tsuyoshi*
PNC TJ1074 98-002, 270 Pages, 1998/02
None
Aoyama, Takafumi; *; Sumino, Kozo; Saikawa, Takuya*
PNC TN9410 98-004, 74 Pages, 1997/12
The Corrosion Product (CP) is the major radiation source in the primary cooling system of an LNFBR plant. It is important to characterize and predict the CP behavior to reduce the personnel exposure dose due to CP deposition. The CP measurement was carried out in the Experimental Fast Reactor JOYO during the 11th annual inspection period when the accumulated reactor thermal power reached about l43GWd. The CP deposition density was measured using a pure germanium detector. The plastic scintillation fiber (PSF) was applied for the gamma-ray dose rate distri bution measurement and compared with the thermoluminescence dosimeter (TLD). The major results obtained by the CP measurements in JOYO are the follows: (1)The major CP nuclides deposited in the primary cooling system are 
Mn and 
CO. Mn is the dominant isotope and it tends to deposit in the cold leg region. On the other hand, Co deposits mainly in the hot leg region. The deposition density of Mn is about seven times as much as that of Co in the cold leg region and twice in the hot leg region. (2)The deposition densities of Mn and Co, and the gamma-dose rate were decreased from the last data in the previous annual inspection period mainly due to the short operation time and the longer cooling time. (3)The continuous gamma-ray dose rate distribution up to 10m can be measured by using the PSF in a few minutes. The PSF is suitable to measure the gamma-ray dose rate distribution in the maintenance work area where it is narrow and the mixture of gamma-ray sources from primary pipings and components. The data base of detailed gamma-ray dose rate distribution was greatly extended by the PSF.
; Yoshida, Eiichi; Furukawa, Tomohiro; Aoto, Kazumi
PNC TN9410 97-092, 87 Pages, 1997/07
This experiment is carried out in the series of the investigation on the damage mechanism of carbon steel. In this paper, the damage situation is considered by structure observations. The test were carried out in 600
C-1200C temperature range, in blowing an argon gas. The reagents are Na
O, NaO and NaOH. From structure observations, the holes are observed on the surface of iron-base material in some test conditions. This result is indicated that the selective reaction occurs. The selective reaction is more obvious as the time exposed to the high temperature is longer. It is considered that the selective reaction occurs after the chemical reaction between iron-base material and sodium compound. The areas, in which Mn-concentration is higher, are observed in products on the surface of specimen.
Aoyama, Takafumi;
PNC TN9420 96-058, 27 Pages, 1996/10
This report introduces the nuclear instrumentation system and the major radiation measurement techniques used in the Experimental Fast Reactor "JOYO". In the introduction of the nuclear instrumentation system, system function and role as reactor plant equipment, specifications and characteristics of neutron detectors, and layout of the system are described. Reactor dosimetry was used to evaluate neutron dose and their spectra for various irradiation tests and surveilance tests performed in JOYO. The multiple-foil activation method which is currently used and the Helium Accumulation fluence Monitor (HAFM) under development are described. The fuel failure detection (FFD) and the failed fuel detection and location (FFDL) systems in which radiation measurement plays a key role are introduced. It was shown some of the major experimental results obtained from a series of fuel failure simulation tests performed in JOYO. Finally, as a new radiation measurement technique, the Plastic Scintillation Fiber (PSF) is described which is a position sensitive radiation detector that can detect the radiation dose rate at the relevant position in the fiber. The PSF is used to upgrade the gamma-ray distribution measurement to accurately evaluate the Corrosion Products (CPs) behavior in the JOYO primary coolant system.
Aoto, Kazumi; ; Hirakawa, Yasushi
PNC TN9410 97-055, 128 Pages, 1996/07
Several material analyses on damage of the floor liner made of a mild steel which was in the test cell of the second sodium leak and combustion experiment (Test-2) performed in OEC/PNC on June 7 in 1996 were carried out to clarify the following issues. (1)Difference of the corrosion mechanism of Test-2 liner to that of the first sodium leak and combustion experiment(Test-1) liner. (2)The vital factor which can desides corrosion mechanism and damage location. The following analyses were accomplished. (a)Microstructure observation (b)EPMA for cross-section of vicinity of corroded area (c)X-ray diffraction(XRD) for the interface between corrosion product-liner(mild steel) The differences between the corrosion mechanism of Test-1 liner which is seemed to be the same that of "MONJU" liner and that of Test-2 liner is discussed based on the results of these material analyses. As the result, the Na-Fe double oxidization with mechanical/chemical removal of reaction product can be occurred on the Test-1 and "MONJU" liner. On the other hand, a hot-corrosion, taht is the molten salt type corrosion is subject to be thinning of the Test-2 liner. All failures of Test-2 liner surround at the halfway up a convex. Considering the above corrosion mechanism, that fact leads that significant damage is occurred at the molten salt level.
