Synthesis of heterostructured SiC and C-SiC nanotubes by ion irradiation-induced changes in crystallinity

Taguchi, Tomitsugu; Yamamoto, Shunya; Kodama, Katsuaki; Asaoka, Hidehito

Carbon, 95, p.279 - 285, 2015/12

https://doi.org/10.1016/j.carbon.2015.08.056

Amorphous SiC nanotubes are successfully synthesized by 340 keV Si ions irradiation of polycrystalline SiC nanotubes for the first time. A polycrystalline/amorphous heterostructure SiC nanotube, in which polycrystalline SiC and amorphous SiC coexist in the same nanotube, is also synthesized by ions irradiation with a mask in front of polycrystalline SiC nanotube. According to electron energy loss spectroscopy evaluation, the plasmon energies of SiC nanotube change rapidly at the interface between polycrystalline and amorphous regions. The volume swelling by amorphization evaluated from the differences of plasmon energies is approximately 5.0%. This result reveals that the further relaxed amorphous SiC nanotubes with higher density can be produced. The graphitic shells in carbon layer of C-SiC nanotube gradually bend to the radial direction of nanotube by the ion irradiation. Since the graphite (002) spots in the selected area electron diffraction pattern are clearly observed even after the ion irradiation, the carbon layer in C-SiC nanotube has certain crystallinity. Moreover, the new multi-walled carbon nanotube with the graphitic shells completely parallel to the radial direction of nanotube is also produced inside the amorphous SiC tubular layer in the case of C-SiC nanotube with large caliber.

Evaluation for the transient Burst property of austenitic steel fuel Claddings irradiated as the MONJU type Fuel Assemblies (MFA-1&MFA-2)in FFTF

; ; Sakamoto, Naoki; *; Akasaka, Naoaki;

JNC TN9400 2000-095, 110 Pages, 2000/07

JNC-TN9400-2000-095.pdf:13.57MB

The effects of high fluence irradiation and swelling on the transient burst properties of austenitic steel fuel claddings; PNC316 and 15Cr-20Ni stcel, which were irradiated as the MONJU type fuel assemblies (MFA-1&MFA-2) in the FFTF reactor, were investigated. The temperature-transient-to-burst tests were conducted on a total of eight irradiation conditions. Fractographic examination and TEM observation were performed in order to evaluate the effect of high dose irradiation on the transient burst property and the relation between failure mechanism and microstructural change during rapid (ramp) heating. The results of the PIE showed that there was no significant effect of irradiation on the transient burst properties of these fuel claddings under the irradiation conditions examined. the results obtained in this study are as follows; (1)The rupture temperature of the irradiated PNC316 fuel cladding of MFA-1 was as same as that of our previous works for the fluence range up to 2.1310 n/m. There was no noticeable decrease in rupture temperature with increasing fluence in lower hoop stress region(100MPa). (2)The rupture temperature of the irradiated 15Cr-20Ni fuel cladding of MFA-2 was almost as same as that of as-received cladding for the hoop stress range up to about 200MPa. The rupture temperature did not decrease significantly with fluence. (3)The rupture temperature of the irradiated PNC316 cladding tested at hoop stress 69MPa, which was the design hoop stress for MONJU fuel, was 1055.6C. This suggested that the design cladding maximum temperature limit for MONJU (830C) was conservative. (4)There was no obvious relation between rupture temperature, swelling and microstructural change during transient heating under the irradiation conditions examined.

Implantation mode dependence of damage structure depth profiles in AlO irradiated with triple beam of H, He and heavy ions

Katano, Yoshio*; Aruga, Takeo; Yamamoto, Shunya; Nakazawa, Tetsuya; Yamaki, Daiju

Proceedings of 2000 International Conference on Ion Implantation Technology (IIT 2000), p.805 - 808, 2000/00

no abstracts in English

Microstructures of type 316 model alloys neutron-irradiated at 513 K to 1 dpa

Miwa, Yukio; Tsukada, Takashi; Tsuji, Hirokazu; Nakajima, Hajime

Journal of Nuclear Materials, 271-272, p.316 - 320, 1999/00

https://doi.org/10.1016/S0022-3115(98)00717-X

no abstracts in English

High temperature low cycle fatigue of 21/4Cr-1Mo steel for the HTTR reactor vessel

Nishi, Hiroshi

JAERI-Research 94-031, 14 Pages, 1994/11

JAERI-Research-94-031.pdf:0.92MB

no abstracts in English

Atomic structure of ion tracks in fluorite structure oxides; Comparison with CeO and ZrO

Takaki, Seiya

no journal, , 

Oxide ceramics with fluorite-structure have been studied as advanced nuclear application, so it is important to clarify the irradiation-induced microstructure. Especially, radiation damage induced by fission fragments with 70-100 MeV, induce high-density electronic excitation in the materials to result in forming cylindrical defect, so called ion track. This study aims to clarify and compare with the structure of ion tracks in CeO and cubic ZrO (YSZ) irradiated with swift heavy ions. It was shown that the density of vacancy at the core damage region of ion tracks is increased and the O anion lattice is preferentially disordered at such region. On the other hand, the size and the areal density of ion tracks in YSZ is smaller than those of CeO. The difference of ion tracks between CeO and YSZ is presumably due to the difference in the recovery process from the thermal spike regime, which is influenced by the presence of structural vacancy in oxide sublattice.

Investigation of in-reactor cesium chemical behavior in TEPCO's Fukushima Daiichi Nuclear Power Station accident, 6; Simulation study on microstructure of Cs-bearing particle

Oishi, Yuji*; Nakamori, Fumihiro*; Muta, Hiroaki*; Kurosaki, Ken*; Yamanaka, Shinsuke*; Sakata, Takao*; Sato, Kazuhisa*; Yasuda, Hidehiro*; Osaka, Masahiko

no journal, , 

Simulant material of Cs-bearing particle was synthesized from the melted glass of which composition was selected based on the composition of the Cs-bearing particle. The relationship between the nucleation behavior of Franklinite (ZnFeO) and cooling speed was studied. The possibility of the formation of Franklinite phase through spinodal decomposition was also evaluated.

Mass production technology development of 9Cr-ODS steel; Development of Prototype large ATTRItor for mass production of ODS steel (PATTRIODS) and test production

Oka, Hiroshi; Tanno, Takashi; Yano, Yasuhide; Otsuka, Satoshi; Kaito, Takeji; Tachi, Yoshiaki

no journal, , 

As part of the development of mass production technology for ODS steel cladding tubes, a large attritor ball-mill PATTRIODS (Prototype large ATTRItor for mass production of ODS steel) was developed, which is a mechanical alloying device for mass production. The powder amount of throughput of PATTRIODS is 30 kg, which is three times the conventional small type attritor. In order to control the amount of oxygen during mechanical alloying, inert gas replacement capability for the pulverization tank and the powder collecting container is adopted. The production test of ODS steel using PATTRIODS revealed that PATTRIODS had the same level of oxygen controllability as the existing small type attritor.

Irradiation induced defects analysis in the heat affected zone of a reactor pressure vessel steel by transmission electron microscopy

Shimodaira, Masaki; Ha, Yoosung; Takamizawa, Hisashi; Seto, Hitoshi*; Katsuyama, Jinya

no journal, , 

no abstracts in English

Characterization of Iron-based high-entropy alloy

Wakai, Eiichi; Shibayama, Tamaki*; Noto, Hiroyuki*; Wakui, Takashi

no journal, , 

In this study, we fabricated a prototype iron-based high-entropy alloy (Fe-Mn-V-Cr-Al-C) composed of low activation elements (free of Ni and Co) by radio frequency melting method and evaluated its basic properties, aiming to apply it to new functional materials for high-energy accelerator target system components, nuclear reactors and fusion reactors. XRD analysis of this material revealed that it has a BCC crystal structure, in which vanadium carbide (VC) is precipitated. This material was found not only to be magnetic, but also to have a fairly small magnetic domain structure. As for the grain size, relatively small grains (about 20-50 m) were observed despite the homogenization heat treatment at 1150C. With regard to strength properties, the results of Vickers hardness measurements indicated that the alloy was much harder than ordinary iron alloys, slightly exceeding pure tungsten, and elastic wave velocity measurements showed that it was faster than iron-based materials and had a higher elastic modulus than stainless steel.