Level structures of Ca cast doubt on a doubly magic Ca

Chen, S.*; Browne, F.*; Doornenbal, P.*; Lee, J.*; Obertelli, A.*; Tsunoda, Yusuke*; Otsuka, Takaharu*; Chazono, Yoshiki*; Hagen, G.*; Holt, J. D.*; et al.

Physics Letters B, 843, p.138025_1 - 138025_7, 2023/08

https://doi.org/10.1016/j.physletb.2023.138025

Gamma decays were observed in Ca and Ca following quasi-free one-proton knockout reactions from Sc. For Ca, a ray transition was measured to be 1456(12) keV, while for Ca an indication for a transition was observed at 1115(34) keV. Both transitions were tentatively assigned as the decays. A shell-model calculation in a wide model space with a marginally modified effective nucleon-nucleon interaction depicts excellent agreement with experiment for level energies, two-neutron separation energies, and reaction cross sections, corroborating the formation of a new nuclear shell above the N = 34 shell. Its constituents, the and orbitals, are almost degenerate. This degeneracy precludes the possibility for a doubly magic Ca and potentially drives the dripline of Ca isotopes to Ca or even beyond.

"Southwestern" boundary of the island of inversion; First study of low-lying bound excited states in V and V

Elekes, Z.*; Juhsz, M. M.*; Sohler, D.*; Sieja, K.*; Yoshida, Kazuki; Ogata, Kazuyuki*; Doornenbal, P.*; Obertelli, A.*; Achouri, N. L.*; Baba, Hidetada*; et al.

Physical Review C, 106(6), p.064321_1 - 064321_10, 2022/12

https://doi.org/10.1103/PhysRevC.106.064321

The low-lying level structure of V and V was investigated for the first time. The neutron knockout reaction and inelastic proton scattering were applied for V while the neutron knock-out reaction provided the data for V. Four and five new transitions were determined for V and V, respectively. Based on the comparison to our shell-model calculations using the Lenzi-Nowacki-Poves-Sieja (LNPS) interaction, three of the observed rays for each isotope could be placed in the level scheme and assigned to the decay of the first 11/2 and 9/2 levels. The (,) excitation cross sections for V were analyzed by the coupled-channels formalism assuming quadrupole plus hexadecapole deformations. Due to the role of the hexadecapole deformation, V could not be unambiguously placed on the island of inversion.

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 1; Project overview and progress until 2020

Yamano, Hidemasa; Takai, Toshihide; Emura, Yuki; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; Morita, Koji*; Nakamura, Kinya*; Fukai, Hirofumi*; et al.

Proceedings of 13th International Topical Meeting on Nuclear Reactor Thermal-Hydraulics, Operation and Safety (NUTHOS-13) (Internet), 12 Pages, 2022/09

This paper describes the project overview and progress of experimental and analytical studies conducted until 2020. Specific results in this paper are the measurement of the eutectic reaction rates and the validation of physical model describing the eutectic reaction in the analysis code through the numerical analysis of the BC-SS eutectic reaction rate experiments in which a BC pellet was placed in a SS crucible.

Stabilization treatment of nuclear fuel material contained with organic matter

Senzaki, Tatsuya; Arai, Yoichi; Yano, Kimihiko; Sato, Daisuke; Tada, Kohei; Ogi, Hiromichi*; Kawanobe, Takayuki*; Ono, Shimpei; Nakamura, Masahiro; Kitawaki, Shinichi; et al.

JAEA-Testing 2022-001, 28 Pages, 2022/05

JAEA-Testing-2022-001.pdf:2.33MB

In preparation for the decommissioning of Laboratory B of the Nuclear Fuel Cycle Engineering Laboratory, the nuclear fuel material that had been stored in the glove box for a long time was moved to the Chemical Processing Facility (CPF). This nuclear fuel material was stored with sealed by a polyvinyl chloride (PVC) bag in the storage. Since it was confirmed that the PVC bag swelled during storage, it seems that any gas was generated by radiolysis of the some components contained in the nuclear fuel material. In order to avoid breakage of the PVC bag and keep it safety for long time, we began the study on the stabilization treatment of the nuclear fuel material. First, in order to clarify the properties of nuclear fuel material, radioactivity analysis, component analysis, and thermal analysis were carried out. From the results of thermal analysis, the existence of organic matter was clarified. Then, ion exchange resin with similar thermal characteristics was selected and the thermal decomposition conditions were investigated. From the results of these analyzes and examinations, the conditions for thermal decomposition of the nuclear fuel material contained with organic matter was established. Performing a heat treatment of a small amount of nuclear fuel material in order to confirm the safety, after which the treatment amount was scaled up. It was confirmed by the weight change after the heat treatment that the nuclear fuel material contained with organic matter was completely decomposed.

Investigation of the ground-state spin inversion in the neutron-rich Cl isotopes

Linh, B. D.*; Corsi, A.*; Gillibert, A.*; Obertelli, A.*; Doornenbal, P.*; Barbieri, C.*; Chen, S.*; Chung, L. X.*; Duguet, T.*; Gmez-Ramos, M.*; et al.

Physical Review C, 104(4), p.044331_1 - 044331_16, 2021/10

AA2021-0468.pdf:1.29MB

https://doi.org/10.1103/PhysRevC.104.044331

no abstracts in English

Observation of Eu adsorption band in the CMPO/SiO-P column by neutron resonance absorption imaging

Miyazaki, Yasunori; Watanabe, So; Nakamura, Masahiro; Shibata, Atsuhiro; Nomura, Kazunori; Kai, Tetsuya; Parker, J. D.*

JPS Conference Proceedings (Internet), 33, p.011073_1 - 011073_7, 2021/03

https://doi.org/10.7566/JPSCP.33.011073

Neutron resonance absorption imaging was adapted to observe the Eu band adsorbed in the CMPO/SiO-P column for minor actinide recovery by extraction chromatography. Several wet columns were prepared by either light water or heavy water and compared with the dry column to evaluate the neutron transmission. The neutron transmission spectra showed that 45% was transmitted through the dry column while 20% and 40% were transmitted through the wet columns of light water and heavy water, respectively. The results indicated that heavy water is more applicable than light water to observe the Eu adsorption band in the CMPO/SiO-P column.

Simple pretreatment method for tritium measurement in environmental water samples using a liquid scintillation counter

Nakasone, Shunya*; Yokoyama, Sumi*; Takahashi, Tomoyuki*; Ota, Masakazu; Kakiuchi, Hideki*; Sugihara, Shinji*; Hirao, Shigekazu*; Momoshima, Noriyuki*; Tamari, Toshiya*; Shima, Nagayoshi*; et al.

Plasma and Fusion Research (Internet), 16, p.2405035_1 - 2405035_5, 2021/02

https://doi.org/10.1585/pfr.16.2405035

Removal of impurities such as organic and other types of dissolved matters from environmental water samples is required for precise analysis of tritium with a liquid scintillation counting method. In general, a distillation method is a conventional one for tritium analysis in environmental water samples, but is a time-consuming process that takes 24 hours for removal of impurities. We have proposed a rapid pretreatment method for tritium analysis, that uses ion exchange resins. In this study, we performed batch experiments, to evaluate the effectiveness of the ion exchange resins on the tritium measurement. The results obtained demonstrated that removal of impurities in the sample water by ion exchange resins can be achieved during a short period of time (i.e., in 5 min).

Shell evolution of = 40 isotones towards Ca; First spectroscopy of Ti

Corts, M. L.*; Rodriguez, W.*; Doornenbal, P.*; Obertelli, A.*; Holt, J. D.*; Lenzi, S. M.*; Menndez, J.*; Nowacki, F.*; Ogata, Kazuyuki*; Poves, A.*; et al.

Physics Letters B, 800, p.135071_1 - 135071_7, 2020/01

https://doi.org/10.1016/j.physletb.2019.135071

Excited states in the = 40 isotone Ti were populated via the V(,)Ti reaction at 200 MeV/nucleon at the Radioactive Isotope Beam Factory and studied using -ray spectroscopy. The energies of the and transitions, observed here for the first time, indicate a deformed Ti ground state. These energies are increased compared to the neighboring Cr and Fe isotones, suggesting a small decrease of quadrupole collectivity. The present measurement is well reproduced by large-scale shell-model calculations based on effective interactions, while ab initio and beyond mean-field calculations do not yet reproduce our findings.

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 1; Project overview

Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro; Kikuchi, Shin; Emura, Yuki; Kamiyama, Kenji; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; et al.

Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.418 - 427, 2019/09

Eutectic reactions between boron carbide (BC) and stainless steel (SS) as well as its relocation are one of the key issues in a core disruptive accident (CDA) evaluation in sodium-cooled fast reactors. Since such behaviors have never been simulated in CDA numerical analyses, it is necessary to develop a physical model and incorporate the model into the CDA analysis code. This study is focusing on BC-SS eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in the range from solid to liquid state. The physical model is developed for a severe accident computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress of experimental and analytical studies by 2017. Specific results in this paper is boron concentration distributions of solidified BC-SS eutectic sample in the eutectic melting experiments, which would be used for the validation of the eutectic physical model implemented into the computer code.

Analysis on adsorbent for spent solvent treatment by micro-PIXE and EXAFS

Arai, Yoichi; Watanabe, So; Ono, Shimpei; Nakamura, Masahiro; Shibata, Atsuhiro; Nakamura, Fumiya*; Arai, Tsuyoshi*; Seko, Noriaki*; Hoshina, Hiroyuki*; Hagura, Naoto*; et al.

International Journal of PIXE, 29(1&2), p.17 - 31, 2019/00

https://doi.org/10.1142/S0129083519500128

The spent PUREX solvent containing U and Pu is generated from the reprocessing process of spent nuclear fuel. The nuclear material removal is important for the safe storage or disposal of the spent solvent. Our previous study revealed that the adsorbent with the iminodiacetic acid (IDA) functional group is one of the most promising materials for designing the nuclear material recovery process. Accordingly, an IDA-type adsorbent was synthesized by using graft polymerization technology or a chemical reaction to improve the adsorption rate and capacity. The synthesized IDA-type adsorbent was characterized by micro particle-induced X-ray emission (PIXE) and extended X-ray absorption fine structure (EXAFS) analyses. The micro-PIXE analysis revealed that Zr was adsorbed on the whole synthesized adsorbents and quantified the microamount of adsorbed Zr. Moreover, EXAFS suggested that Zr in the aqueous solution and solvent can be trapped by the IDA group with different mechanisms.