Chiera, N. M.*; Sato, Tetsuya; Eichler, R.*; Tomitsuka, Tomohiro; Asai, Masato; Adachi, Sadia*; Dressler, R.*; Hirose, Kentaro; Inoue, Hiroki*; Ito, Yuta; et al.
Angewandte Chemie; International Edition, 60(33), p.17871 - 17874, 2021/08
The formation and the chemical characterization of single atoms of dubnium (Db, element 105), in the form of its volatile oxychloride, was investigated using the on-line gas phase chromatography technique, in the temperature range 350 - 600 C. Under the exact same chemical conditions, comparative studies with the lighter homologs of group-5 in the Periodic Table clearly indicate the volatility sequence being NbOCl TaOCl DbOCl. From the obtained experimental results, thermochemical data for DbOCl were derived. The present study delivers reliable experimental information for theoretical calculations on the chemical properties of transactinides.
Herranz, L. E.*; Jacquemain, D.*; Nitheanandan, T.*; Sandberg, N.*; Barr, F.*; Bechta, S.*; Choi, K.-Y.*; D'Auria, F.*; Lee, R.*; Nakamura, Hideo
Progress in Nuclear Energy, 127, p.103432_1 - 103432_14, 2020/09
Guguchia, Z.*; Frandsen, B. A.*; Santos-Cottin, D.*; Shamoto, Shinichi; Gauzzi, A.*; Uemura, Yasutomo*; 12 of others*
Physical Review Materials (Internet), 3(4), p.045001_1 - 045001_9, 2019/04
We have studied the Mott transition of BaCoS by pressure and Ni substitution using SR, and examined the appearance of the quantum phase transition. The results show that both quantum phase transitions are first-order transitions at zero temperature.
Eichler, R.*; Asai, Masato; Brand, H.*; Chiera, N. M.*; Di Nitto, A.*; Dressler, R.*; Dllmann, Ch. E.*; Even, J.*; Fangli, F.*; Goetz, M.*; et al.
EPJ Web of Conferences, 131, p.07005_1 - 07005_7, 2016/12
In recent years gas-phase chemical studies assisted by physical pre-separation allowed for the productions and investigations of fragile single molecular species of superheavy elements. The latest highlight is the formation of very volatile hexacarbonyl compound of element 106, Sg(CO). Following this success, second-generation experiments were performed to measure the first bond dissociation energy between the central metal atom and the surrounding ligand. The method using a tubular decomposition reactor was developed and successfully applied to short-lived Mo(CO), W(CO), and Sg(CO).
Steinegger, P.*; Asai, Masato; Dressler, R.*; Eichler, R.*; Kaneya, Yusuke*; Mitsukai, Akina*; Nagame, Yuichiro; Piguet, D.*; Sato, Tetsuya; Schdel, M.; et al.
Journal of Physical Chemistry C, 120(13), p.7122 - 7132, 2016/04
A new experimental method "vacuum chromatography" has been developed to measure adsorption enthalpy of superheavy elements, and its feasibility has been examined using short-lived thallium isotopes. The short-lived thallium isotopes were produced at the JAEA tandem accelerator. The thallium ion beam prepared with an on-line isotope separator which ionized and mass-separated the thallium isotopes was injected into an isothermal vacuum chromatography apparatus. A temperature-dependent adsorption property of thallium atom on SiO surface were measured. The adsorption enthalpy of thallium was determined to be 158 kJ/mol. The thallium is a homolog of element 113. Thus, the vacuum chromatography developed in this study enables us to perform chemical experiments for short-lived superheavy elements with half-lives of a order of one second.
Takano, Kazuya; Mori, Tetsuya; Kishimoto, Yasufumi; Hazama, Taira
Proceedings of International Conference on the Physics of Reactors; The Role of Reactor Physics toward a Sustainable Future (PHYSOR 2014) (CD-ROM), 13 Pages, 2014/09
This paper describes details of the IAEA/CRP benchmark calculation by JAEA on the control rod withdrawal test in the Phenix End-of-Life Experiments. The power distribution deviation by the control rod insertion/withdrawal, which is the major target of the benchmark, is well simulated by calculation. In addition to the CRP activities, neutron and photon transport effect is evaluated in the nuclear heating calculation of the benchmark analysis. It is confirmed that the neutron and photon transport effect contributes to the improvement of the absolute power calculation results in the breeder blanket region.
Pascal, V.*; Prulhire, G.*; Vanier, M.*; Fontaine, B.*; Devan, K.*; Chellapandi, P.*; Kriventsev, V.*; Monti, S.*; Mikityuk, K.*; Chenu, A.*; et al.
Proceedings of International Conference on the Physics of Reactors; The Role of Reactor Physics toward a Sustainable Future (PHYSOR 2014) (CD-ROM), 16 Pages, 2014/09
no abstracts in English
Monti, S.*; Toti, A.*; Stanculescu, A.*; Pascal, V.*; Fontaine, B.*; Herrenschmidt, A.*; Prulhiere, G.*; Vanier, M.*; Varaine, F.*; Vasile, A.*; et al.
IAEA-TECDOC-1742, 247 Pages, 2014/06
Pascal, V.*; Prulhire, G.*; Fontaine, B.*; Devan, K.*; Chellapandi, P.*; Kriventsev, V.*; Monti, S.*; Mikityuk, K.*; Semenov, M.*; Taiwo, T.*; et al.
Proceedings of 2013 International Congress on Advances in Nuclear Power Plants (ICAPP 2013) (USB Flash Drive), 11 Pages, 2013/04
The control rod withdrawal test was one of the various Phenix End-of-Life tests performed in 2009. The main goal was to determine the impact of a rod insertion and/or extraction on the radial power distribution in the fissile core at nominal power. The framework of the Technical Working Group on Fast Reactors (TWG-FR) activities in IAEA, decided to launch a Coordinated Research Project (CRP), devoted to benchmarking analyses on the test. The CRP was performed by experts coming from CEA, ANL, IGCAR, IPPE, IRSN, JAEA, KIT and PSI. After a short description of the test conducted in the Phenix reactor, this paper presents some results obtained in the course of the CRP with special emphasis on control rod efficiencies and power deformation by subassemblies. The paper also discusses the discrepancies found when comparing calculated results with experimental data as well as some preliminary conclusions on the source of these discrepancies.
Curti, E.*; Aimoz, L.*; Kitamura, Akira
Journal of Radioanalytical and Nuclear Chemistry, 295(3), p.1655 - 1665, 2013/03
Se is a major dose-determining redox-sensitive nuclide in safety analysis of radioactive waste disposal sites. In aqueous solutions, selenium forms soluble anionic species (SeO and SeO) that hardly sorb on negatively charged surfaces of common host-rock minerals. However, Se is known to have a strong affinity with sulphides and interacts with pyrite, a common minor mineral of argillaceous rocks being considered as host rocks for radioactive waste repositories in Switzerland etc. In this study, we present micro- and bulk X-ray spectroscopy data (-XRF, -XANES, and EXAFS) showing that, under nearly anoxic conditions, dissolved SeO and SeO sorb directly onto the pyrite surface and are subsequently reduced to Se with increasing ageing time (up to 8 months). These results suggest that the mobility of Se released from radioactive waste could efficiently be reduced through uptake on the pyrite surface followed by transformation into a sparingly soluble reduced form.
Bart, G.*; Bakker, K.*; Hellwig, C.*; Kihara, Yoshiyuki; Ozawa, Takayuki; Wallin, H.*; Shigetome, Yoshiaki
Journal of Nuclear Science and Technology, 44(3), p.329 - 336, 2007/03
Within the FUJI collaboration program among Japan Atomic Energy Agency (JAEA, former JNC), Paul Scherrer Institute (PSI, Switzerland) and Nuclear Research and Consultancy Group (NRG, the Netherlands) the production paths of plutonium and neptunium mixed oxide- (sphere-pac- and vipac-) particle fuels (20wt% Pu and 5wt% Np) are tested as well as the initial sintering and power-to-melt behavior under simulated FBR conditions. The various fuel forms were produced at PSI under the support of JNC, the irradiations were accomplished at High Flux Reactor (HFR) in Petten, the post irradiation examinations are being achieved mainly at NRG and the fuel modelling being performed at JNC and PSI. The present paper reviews mainly the project planning, fuel behaviour- pre-calculations and the fuel- and fuel segment- production. A short overview of the irradiation conditions and ceramographic post irradiation examination analyses is also given.
Hiess, A.*; Bernhoeft, N.*; Metoki, Naoto; Lander, G.*; Roessli, B.*; Sato, Noriaki*; Aso, Naofumi*; Haga, Yoshinori; Koike, Yoshihiro*; Komatsubara, Takemi*; et al.
Journal of Physics; Condensed Matter, 18(27), p.R437 - R451, 2006/07
This topical review presents results from neutron inelastic scattering experiments on single crystals of UPdAl. We present a detailed and complete characterization of the wave vector- and energy-dependent magnetization dynamics in UPdAl as measured by neutron inelastic scattering primarily in the form of extensive surveys in energy-momentum space under a wide range of experimental conditions, and put our observations in context with data that has been published previously by two independent groups. This study yields unique insight into the low-temperature ground state, which exhibits a microscopic coexistence of antiferromagnetism and superconductivity, makingUPdAl one of the most accessible heavy-fermion superconductors that can be fully characterized by neutron spectroscopy.
Nakamura, Masahiro; Ozawa, Takayuki; Morihira, Masayuki; Kihara, Yoshiyuki
JAEA-Research 2006-028, 146 Pages, 2006/03
The collaboration project concerning sphere-pac fuel among JNC (Japan Nuclear Cycle Development Institute, now Japan Atomic Energy Agency), Swiss PSI (Paul Scherrer Institut) and Dutch NRG (Nuclear Research and Consultancy Group) was performed from 1996 till 2005. The target of this project is comparative irradiation tests of sphere-pac fuel in the HFR (High Flux Reactor) in Petten in the Netherlands with pellet fuel and vipac fuel. Total 16 fuel segments (8 pins) containing 5%Np-MOX sphere-pac segments were irradiated. No fuel failure was occurred. Restructuring of sphere-pac fuel was quickly progressed in early stage of irradiation, and formation of the central hole was almost completed within 48 hours steady state irradiation. According to the results of the power-to-melt test, the power to melt linear heat rates were estimated as 60kW/m for the sphere-pac fuel and as 73kW/m for the pellet fuel under HFR irradiation conditions. Irradiation behaviors of the vipac fuel and Np-MOX sphere-pac fuel were basically similar to that of the MOX sphere-pac fuel. However, the central hole of the Np-MOX sphere-pac fuel was larger than that of MOX sphere-pac fuel in the restructuring test. It suggests that the thermal conductivity of Np-MOX fuel is smaller than that of MOX fuel.
Fujiwara, Kenso; Tomura, Tsutomu*; Tobita, Minoru*; Tits, J.*; Curti, E.*
no journal, ,
Ra-226 is a safety-relevant radionuclide in performance assessments of high-level waste repositories and has thus been deserved special attention. The aim of the proposed study is to provide new key data on the interaction of Ra with calcite and witherite. In this study, the interaction of Ca with calcite and Ba with witherite was measured by using Ca-45 and Ba-133.
Fujiwara, Kenso; Tomura, Tsutomu*; Tobita, Minoru*; Suzuki, Yasuyuki*; Tits, J.*; Curti, E.*
no journal, ,
The aim of the proposed study is to provide new key data on the interaction of Ra with calcite, witherite and barite in the presence of selected clay materials Kunigel V1 bentonite representing the backfill, respectively host-rock, of the high-level waste repositories planned in Japan.
Kitamura, Akira; Curti, E.*; Aimoz, L.*
no journal, ,
A batch experiment was performed to investigate sorption of selenium(IV/VI) onto pyrite (FeS). Polished chips of natural pyrite were reacted with selenium(IV/VI) solutions with pH 89 for 2 months at 80 C under N atmosphere. Micro X-ray Fluorescence (-XRF) maps and Micro X-ray Absorption Spectra (-XAS) were collected in suitable sample holders flushed with inert gas. Crashed grains of natural pyrite were also used for comparison with pyrite chips. It was found that equivalent sulfur was dissolved to solutions after selenium sorption, sorption of selenium onto pyrite was highly heterogeneous, and both tetravalent and hexavalent selenium were reduced to selenium(0) after sorption onto pyrite.
Fujiwara, Kenso; Iijima, Kazuki; Tomura, Tsutomu*; Tobita, Minoru*; Suzuki, Yasuyuki*; Tits, J.*; Curti, E.*
no journal, ,
no abstracts in English
Tanaka, Hidekazu*; Kurita, Nubuyuki*; Umegaki, Izumi*; Ono, Toshio*; Laver, M.*; Niedermayer, Ch.*; Regg, Ch.*; Kawamura, Seiko; Nakajima, Kenji; Kakurai, Kazuhisa
no journal, ,
Sato, Tetsuya; Kaneya, Yusuke*; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Mitsukai, Akina*; Osa, Akihiko; Makii, Hiroyuki; Hirose, Kentaro; Nagame, Yuichiro; et al.
no journal, ,
Our experimental results on the first ionization potential measurement of lawrencium (Lr, element 103) have strongly suggested that the Lr atom has a [Rn] configuration as a result of the influence of strong relativistic effects. The configuration is different from that expected from the lanthanide homologue, lutetium (Lu). According to a semi-empirical consideration, it is expected that the change of the electronic configuration leads higher volatility of Lr than that of Lu. In this work, adsorption behaviors of Lr and various short-lived rare earth isotopes on a tantalum surface were investigated via observation of their surface ionization efficiencies. It was found that Lr would behave like low volatile rare earth elements such as Lu contrary to the semi-empirical expectation.
Tomitsuka, Tomohiro; Kaneya, Yusuke*; Sato, Tetsuya; Asai, Masato; Tsukada, Kazuaki; Toyoshima, Atsushi; Mitsukai, Akina; Osa, Akihiko; Nishio, Katsuhisa; Nagame, Yuichiro; et al.
no journal, ,
In order to investigate the adsorption behavior of Lawrencium (Lr, Z = 103) on a Tantalum (Ta) surface, we measured ionization efficiencies of Lr under several temperature conditions of the surface ionization. We observed ionization efficiencies of Lr which were lower than those calculated by the Saha-Langmuir equation in lower temperature region. Based on a temperature dependence of the obtained ionization efficiencies, we discuss the adsorption behavior of Lr on the Ta surface.