Spectral evidence for Dirac spinons in a kagome lattice antiferromagnet

Zeng, Z.*; Zhou, C.*; Zhou, H.*; Han, L.*; Chi, R.*; Li, K.*; Kofu, Maiko; Nakajima, Kenji; Wei, Y.*; Zhang, W.*; et al.

Nature Physics, 20(7), p.1097 - 1102, 2024/07

https://doi.org/10.1038/s41567-024-02495-z

Chemical characterization of a volatile dubnium compound, DbOCl

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

https://doi.org/10.1002/anie.202102808

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.

Probing the quantum phase transition in Mott insulator BaCoS tuned by pressure and Ni substitution

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

https://doi.org/10.1103/PhysRevMaterials.3.045001

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.

Vacuum chromatography of Tl on SiO at the single-atom level

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

https://doi.org/10.1021/acs.jpcc.5b12033

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.

IAEA benchmark calculations on control rod withdrawal test performed during Phenix End-of-Life experiments; Benchmark results and comparisons

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

Benchmark calculations on control rod withdrawal tests performed during Phenix End-of-Life experiments

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.

FUJI, an initial sintering comparison test for pelletized-, sphere-pac- and vipac-fast breeder reactor mixed oxide fuel

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

https://doi.org/10.3327/jnst.44.329

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.

Report of the collaboration project for research and development of sphere-pac fuel among JNC-PSI-NRG (II); Irradiation tests and post irradiation examinations (Joint research)

Nakamura, Masahiro; Ozawa, Takayuki; Morihira, Masayuki; Kihara, Yoshiyuki

JAEA-Research 2006-028, 146 Pages, 2006/03

JAEA-Research-2006-028.pdf:37.95MB

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.

Adsorption of Lawrencium (Z = 103) on a tantalum surface

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.

Study on reductive sorption of Se(IV,VI) onto pyrite with micro-XRF/XAS

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.