発表論文　-　2006年

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[2006_01]

Interactions between molten Flibe and metallic Be

M. Hara, Y. Hatano, M.F. Simpson, G.R. Smolik, J.P. Sharpe, Y. Oya, K. Okuno, M. Nishikawa, T. Terai, S. Tanaka, R.A. Anderl, D.A. Petti, D.-K. Sze

Fusion Engineering and Design, 81 (2006) 561-566

[2006_02]

Quantitative measurement of beryllium-controlled redox of hydrogen fluoride in molten Flibe

M.F. Simpson, G.R. Smolik, J.P. Sharpe, R.A. Anderl, D.A. Petti, Y. Hatano, M. Hara, Y. Oya, S. Fukada, S. Tanaka, T. Terai, D.-K. Sze

Fusion Engineering and Design, 81 (2006) 541-547

[2006_03]

Applicability of β-ray-induced X-ray spectrometry to in situ measurements of tritium retention in plasma-facing materials in ITER

M. Matsuyama, Y. Torikai, N. Bekris, M. Glugla, A. Erbe, W. Naegele, N. Noda, V. Philipps, P. Coad, K. Watanabe

Fusion Engineering and Design, 81 (2006) 163-168

[2006_04]

JUPITER-II molten salt Flibe research: An update on tritium, mobilization and redox chemistry experiments

D.A. Petti, G.R. Smolik, M.F. Simpson, J.P. Sharpe, R.A. Anderl, S. Fukada, Y. Hatano, M. Hara, Y. Oya, T. Terai, D.-K. Sze, S. Tanaka

Fusion Engineering and Design, 81 (2006) 1439-1449

[2006_05]

Monitoring of tritium in diluted gases by detecting bremsstrahlung X-rays

W.M. Shu, M. Matsuyama, T. Suzuki, M.F. Nishi

Fusion Engineering and Design, 81 (2006) 803-808

[2006_06]

Development of a tritium separation process using SDGC

Y. Morimoto, S. Kojima, T. Sasaki, M. Matsuyama, M. Hara, S. Akamaru, M. Numata, T. Kato, K. Watanabe

Fusion Engineering and Design, 81 (2006) 821-826

[2006_07]

Influence of oxygen and carbon on performance of superpermeable membranes

Y. Hatano, A. Livshits, Y. Nakamura, A. Busnyuk, V. Alimov, C. Hiromi, N. Ohyabu, K. Watanabe

Fusion Engineering and Design, 81 (2006) 771-776

[2006_08]

Effect of a magnesium depletion on the Mg-Ni-Y alloy hydrogen absorption properties

M. Hara, S. Morozumi, K. Watanabe

Journal of Alloys and Compounds, 414 (2006) 207-214

[2006_09]

ステンレス鋼中のトリチウムの分布

鳥養祐二, 村田大樹, Ralf-Dieter PENZHORN, 赤石憲也, 渡辺国昭, 松山政夫

真空, 49(3) (2006) 147-149

[2006_10]

Detritiation of type 316 stainless steel by treatment with liquids at ambient temperature

R.-D. Penzhorn, Y. Torikai, M. Matsuyama, K. Watanabe

Journal of Nuclear Materials, 353 (2006) 66-74

[2006_11]

Magnetic Properties of Palladium and Palladium-Platinum Alloy of Various Hydrogen Content

Masanori Hara, Junichi Sakurai, Satoshi Akamaru, Kuniaki Watanabe, Katsuhiko Nishimura, Katsunori Mori, Masao Matsuyama

Materials Transactions, 47(9) (2006) 2373-2376

[2006_12]

Surface coating of small SiO₂ particles with TiO₂ thin layer by using barrel-sputtering system

Satoshi Akamaru, Shingo Higashide, Masanori Hara, Takayuki Abe

Thin Solid Films, 513 (2006) 103-109

[2006_13]

Phase transition and electrochemical capacitance of mechanically treated manganese oxides

Akira Taguchi, Sachio Inoue, Satoshi Akamaru, Masanori Hara, Kuniaki Watanabe, Takayuki Abe

Journal of Alloys and Compounds, 414 (2006) 137-141

[2006_14]

A Newly Developed Non-Destructive Tritium Measurement Technique and Its Application to V-4Cr-4Ti Alloy

LIU Xiang, CHEN Xue, H.HOMMA, Y.HATANO, M.MATSUYAMA

Plasma Science ＆Technology, Vol.8, No.6, Nov. 2006, 741-744

　[2006_01]

    To understand the interactions between molten Flibe and Be, a metallic Be rod was immersed in molten Flibe at 803K under He atmosphere for 210 h. The Be rod was significantly eroded during immersion in molten Flibe, and the Flibe changed from a clear crystal to a brownish-gray marble-like appearance. The concentration of Be⁰ in Flibe was evaluated by dissolving salt samples in acid solutions. This dissolution test is based on the reaction of Be⁰ with proton ions in the acid solutions to generate H₂. Hydrogen gas was generated from Flibe contacted with Be under flowing He. The amounts of gas generated corresponded to mole fractions of [Be⁰]/[Flibe] ranging from 9.9×10^-4 to 7.6×10^-3. On the other hand, no H₂ was generated from Flibe that was not exposed to Be or which was exposed to Be and then given significant H₂.HF.He bubbling. These observations showed that Be does, indeed, dissolve in Flibe as Be⁰. The fact that no Be⁰ was detected after bubbling H₂.HF.He into the salt indicates that Be⁰ is an effective redox agent for reacting HF.

Keywords: 2LiF.BeF₂; Be dissolution; Fluorine potential; Reductant; JUPITER-II

　[2006_02]

    In order to investigate the viability of using Be as a redox agent in a molten Flibe (2LiF-BeF₂) blanket, a series of kinetics experiments were performed in which HF was bubbled through Flibe with varying concentrations of dissolved Be. The feed gas consisted of 910-1800 ppm HF and 0.1-0.2 vol.% H₂, with the balance comprised of He. A cylindrical rod of Be was contacted with the salt for periods of time ranging from 600 to 3600 s, resulting in mole fractions in the salt ranging from 4.3×10^-5 to 2.6×10^-4. Initially, high HF conversion levels in excess of 90% were observed. As HF reacted with the Be, the conversion levels slowly dropped over a period of several hours to a few days. A simple kinetic model, which is first order in both HF and Be concentration has been coupled with a non-mixed reactor model to yield a good fit to the data. Application of this model indicates that Be should be suitable for keeping the TF concentration in the salt below 0.02 ppb.

Keywords: Redox; Beryllium; Flibe; Corrosion; Kinetics

　[2006_03]

    Applicability of β-ray-induced X-ray spectrometry (BIXS) for in situ measurements of tritium retention by plasma-facing materials in ITER was examined using two γ-emitters and a divertor tile with metallic supports employed during D-T fusion experiments in JET. Measurements of the tile with a γ-emitter showed that the presence of the γ-field has no influence in the shape of the β-ray-induced X-ray spectra, although the whole intensity in the observed energy region was dependent on radioactivity of the γ-emitters. To simulate more accurately the in-vessel environment of PFMs, one of the divertor tiles with metallic supports was subjected to BIXS measurements. Although the metallic supports were gamma active, no significant effect was observed on the recorded X-ray spectrum. These results clearly indicate that BIXS can be applied to in situ measurements of tritium retention by PFMs with a simple shielding of the X-ray detector.

Keywords: Tritium retention; In situ measurement; BIXS; Plasma-facing materials; ITER

　[2006_04]

    The second Japan/US Program on Irradiation Tests for Fusion Research (JUPITER-II) began on April 1, 2001. Part of the collaborative research centers on studies of the molten salt 2LiF-BeF₂ (also known as Flibe) for fusion applications. Flibe has been proposed as a self-cooled breeder in both magnetic and inertial fusion power plant designs over the last 25 years. The key feasibility issues associated with the use of Flibe are the corrosion of structural material by the molten salt, tritium behavior and control in the molten salt blanket system, and safe handling practices and releases from Flibe during an accidental spill. These issues are all being addressed under the JUPITER-II program at the Idaho National Laboratory in the Safety and Tritium Applied Research (STAR) facility. In this paper, we review the program to date in the area of tritium/deuterium behavior, Flibe mobilization under accident conditions and testing of Be as a redox agent to control corrosion. Future activities planned through the end of the collaboration are also presented.

Keywords: JUPITER-II; Flibe; Molten salt

　 [2006_05]

    For developing an alternative mean for on-line and real-time tritium monitoring, the method of detecting bremsstrahlung X-rays was examined by measuring the counting rate of bremsstrahlung X-rays as a function of pressure in two mixed tritium gases diluted with hydrogen or helium. At a constant tritium partial-pressure ratio of 0.010, the relationship between the counting rate of bremsstrahlung X-rays, X (cpm) and the total pressure, P (Pa) can be expressed as X = 4.1×10⁵ (1-e^{-4.0 P/100,000}). The counting rate depends only on tritium partial-pressure and the total pressure if the mixed gases contain no other species but hydrogen isotopes and helium isotopes. In addition, the relation between X and P can be simplified to a linear function in the low-pressure region of P<<2.5×10⁴ Pa.

Keywords: Tritium; Monitoring; Bremsstrahlung X-rays; Absorption coefficient

　[2006_06]

    A self-developing gas chromatography (SDGC) process using a column packed with Pd-at.% Pt alloy powder was studied for hydrogen isotope separation at room temperature. Separation experiments of a deuterium-tritium (50% D₂-50% T₂) mixture were carried out using the same SDGC column. The concentrations of tritium in the recovered hydrogen isotope gas were 80 and 75% at 50 and 70% recovery of tritium, respectively. The result of the deuterium-tritium separation experiments suggested considerable potential for the applicability of the SDGC column to the D-T separation process at room temperature.

Keywords: Self-developing gas chromatography; Pd-Pt alloy; Tritium; Isotope separation

　[2006_07]

    In order to understand the applicability of superpermeable membranes for tritium recovery from fusion exhaust gas containing impurities, the influence of oxygen and carbon on the performance of Nb and V membranes was examined by laboratory scale experiments. No significant degradation due to oxygen was observed if the membrane temperature was sufficiently high, i.e. above 700 K, and the bulk oxygen concentration was below 1.5 at.%. It was also possible to avoid the influence of carbon deposition by the operation at high temperatures through the conversion of carbon deposited layer into carbide layer.

Keywords: Superpermeation; Tritium; Recovery; Niobium; Vanadium

　[2006_08]

    To improve the hydrogen absorption properties of Mg₂Ni, three kinds of specimens were prepared. They were denoted as MGNIY, DeMg-MGNIY and DeMg-MIX. The first one was a cast Mg-Ni-Y alloy, the second was prepared by vacuum heating of MGNIY to remove some part of Mg and the third was prepared by vacuum heating of a mixture of pulverized Mg-Y and Mg₂Ni. The term DeMg denotes removal of Mg by vacuum heating. These samples were characterized by XRD, SEM and EPMA and found to be composed of Mg, Mg₂Ni and crystallographically unknown phases. Each material was found to have its own distribution of yttrium. The composition of the crystallographically unknown phase was determined by EPMA to be MgYNi₃. Yttrium-alloying and subsequent DeMg treatment caused a significant improvement in the hydrogen absorption rate. It showed hydrogen uptake amounting to about 3 mass % for DeMg-MGNIY at 473K in 80ks, although the improvement at room temperature could not be distinguished from that of Mg₂Ni. MGNIY gave similar absorption properties with those of DeMg-MGNIY at 473K, but showed significantly slower absorption rate than Mg₂Ni at room temperature. The properties of DeMg-MIX were found to be similar to those of Mg₂Ni at both temperatures. On account of the sample characterization, it was concluded that the improvement in hydrogen uptake by DeMg-MGNIY and MGNIY at 473K was due to their specific yttrium-distribution and catalytic activity.

Keywords: Mg-based alloys; Hydrogen absorption; Magnesium depletion; Mg₂Ni; Yttrium-alloying

　[2006_09]

    To investigate the behavior of hydrogen uptake and release by 316 stainless steel (SS316), as-received and finely polished stainless steel specimens were exposed at 573Ｋ to tritium gas diluted with hydrogen. Then tritium concentration in the exposed specimens was measured as a function of depth using a chemical etching method. All the tritium concentration profiles showed a sharp drop in the range of 10μm from the top surface up to the bulk. The amount of tritium absorbed into the polished specimens was three times larger than that into the as-received spacimen. However, the polishing effects disappeared by exposing to the air for a long time.

　[2006_10]

   The detritiation efficiency of type 316 stainless steel (SS316) using liquids reagents (distilled deionized water, concentrated aqueous ammonia or a diluted hydrochloric acid/nitric acid mixture) was investigated at ambient temperature by means of liquid scintillation counting (LSC) and β-ray-induced ×-ray spectrometry (BIXS). After a fast initial removal of tritium trapped on the outermost surface of SS316 with a rate in the order water ＜ ammonia ＜ acid mixture a slow chronic liberation of tritium into all three liquids sets in. First results indicate that chronic release occurs with a rate of approx. 0.2% per day. The long-term release was found to be largely independent from the kind of liquid agent into which the metal is submerged and from the initial loading of the SS316 specimen. From a practical point of view, the release rate of tritium into liquids is too slow for conditioning applications. Complementary evidence for the occurrence of a chronic liberation of tritium from SS316 into air at ambient temperature was obtained from tritium depth profiling of aged specimens by acid etching.

　[2006_11]

    Magnetic properties of palladium and palladium-platinum alloy (Pd-Pt) of different hydrogen content were measured in a hydrogen atmosphere at ambient temperature using a superconducting quantum interference device (SQUID) magnetometer. It was found that the magnetic susceptibility of Pd and Pd-Pt alloy decreased with increasing hydrogen content. These results were attributed to a change in the electronic structure of the valence band. Increasing hydrogen content in Pd and Pd-Pt alloy causes the Fermi level to rise and the density of states at Fermi level to decrease. Since the magnetic susceptibility is proportional to the density of states at the Fermi level, the magnetic susceptibility decreases with increasing hydrogen content. The magnetic susceptibility of Pd-Pt was smaller than that of Pd over the whole hydrogen content range. This was ascribed to the higher position of the Fermi level of Pd-Pt than that of Pd.

Keywords: palladium alloy; hydride; Fermi level; density of states; magnetic susceptibility

　[2006_12]

    Surface coating of small SiO₂ particles with a thin TiO₂ layer was carried out by using a hexagonal barrel-sputtering system. In order to determine suitable sputtering conditions, the TiO₂ layer was deposited on a glass substrate by reactive sputtering under given total pressures, oxygen fractions, and substrate temperatures. The analysis of X-ray diffraction patterns and ultraviolet-visible absorption spectra showed that the preparation of a TiO₂ layer with the rutile phase requires a high total pressure at room temperature whereas that with the anatase phase requires a moderate total pressure at 498 K. The surface coating of SiO₂ particles by TiO₂ layer was performed under the conditions suitable for either the rutile or anatase phase. It was found from scanning electron microscope, energy-despersion spectrometer, and ultraviolet-visible absorption measurements that the surface of SiO₂ particles was successfully coated with a thin uniform TiO₂ layer with the rutile or anatase phase.

Keywords: Titanium oxide; Barrel-sputtering system; Surface coating; Powdery materials

　[2006_13]

    Mechanical grinding (MG) leads to a sequential phase transition of γ-MnO₂ to form the thermodynamically stable α-Mn₂O₃ and, subsequently, Mn₃O₄ depending on the duration of MG treatment. By MG treatment for 150h, α-Mn₂O₃ became a predominant species. A subsequent transition to Mn₃O₄ was observed on further MG treatment for 200h. The particle size of the resultant manganese oxides was reduced to as small as 20nm after 300h of MG treatment. The change in the specific capacitance of manganese oxides obtained was monitored by XRD and electrochemical experiments. It was observed that the specific capacitance of MG-treated manganese oxides depends on the amount of γ-MnO₂ left without phase transition.

Keywords: Manganese oxides; Phase transition; Mechanical grinding; Supercapacitor

　[2006_14]

    A non-destructive and in-situ technique for the measurement of tritium in materials, namely β-ray-induced X-ray spectrometry(BIXS), has been developed recentry. In the present study a V-4Cr-4Ti alloy was pre-heated at 1000℃ for 2 h to form a recrystallization structure before the tritium absorption experiments were conducted. Firstly the hydrogen isotope gas was chamber. Then hydrogen isotope absorption tests of V-4Cr-4Ti alloy were performed at 400℃ and the atomic concentration of hydrogen isotope in V-4Cr-4Ti alloy was estimated as 0.17％ with a tritium content of approximately 2.5 ppm. Experimental results indicate that BIXS is a quite useful tool for quantitatively measuring the tritium content and tritium exist in the pre-heated V-4Cr-4Ti alloy.

Keywords: tritium, V-4Cr-4Ti, β-ray-induced X-ray spectrometry, tritium measurements