Muon spin relaxation in mixed perovskite (LaAlO)(SrAlTaO) with

Ito, Takashi; Higemoto, Wataru; Koda, Akihiro*; Nakamura, Jumpei*; Shimomura, Koichiro*

Interactions (Internet), 245(1), p.25_1 - 25_7, 2024/12

https://doi.org/10.1007/s10751-024-01866-5

Pulsed muon facility of J-PARC MUSE

Shimomura, Koichiro*; Koda, Akihiro*; Pant, A. D.*; Sunagawa, Hikaru*; Fujimori, Hiroshi*; Umegaki, Izumi*; Nakamura, Jumpei*; Fujihara, Masayoshi; Tampo, Motonobu*; Kawamura, Naritoshi*; et al.

Interactions (Internet), 245(1), p.31_1 - 31_6, 2024/12

https://doi.org/10.1007/s10751-024-01863-8

Quantifying uncertainty induced by scattering angle distribution using maximum entropy method

Maruyama, Shuhei; Yamamoto, Akio*; Endo, Tomohiro*

Annals of Nuclear Energy, 205, p.110591_1 - 110591_13, 2024/09

https://doi.org/10.1016/j.anucene.2024.110591

Records of the riverine discharge of I in riverbank sediment after the Fukushima accident

Nakanishi, Takahiro; Sakuma, Kazuyuki; Oyama, Takuya; Hagiwara, Hiroki; Suzuki, Takashi

Environmental Pollution, 355, p.124213_1 - 124213_7, 2024/08

https://doi.org/10.1016/j.envpol.2024.124213

This study investigated the transport behavior of I by riverbank surveys conducted from 2013 to 2015 in a watershed where the I/Cs activity ratio is low in the mountainous area and high in the plain as of 2011. Until 2015, the I/Cs activity ratio of the levee crown in the studied watershed was similar to that of the surrounding area in 2011. However, the I/Cs ratios of the surface riverbank sediments were all low, indicating that radionuclides transported from the mountainous area were deposited on the riverbank in the plain. The vertical distribution of the I/Cs ratio in the riverbank sediments indicated that some I and Cs deposited during the accident remained in the lower layers, but most were eroded immediately after the accident. Based on the I/Cs ratios of sediments deposited on the riverbank, which remained constant until 2015 after the accident, the amount of I discharged to the ocean was determined from the previously evaluated Cs discharge. It was calculated that 1.810 Bq and 1.210 Bq of I were discharged with sediment from the studied watershed and the contaminated river watersheds (Abukuma River and Fukushima coastal rivers, including the study river), respectively. The results of this study indicate that the continuous I discharge from the river contribute little to their amount in the seafloor sediments along the Fukushima coast.

Effect of water activity on the mechanical glass transition and dynamical transition of bacteria-solute systems

Kawai, Kiyoshi*; Sogabe, Tomochika*; Nakagawa, Hiroshi; Yamada, Takeshi*; Koseki, Shigenobu*

Journal of Food Engineering, 375, p.112066_1 - 112066_9, 2024/08

https://doi.org/10.1016/j.jfoodeng.2024.112066

The purpose of this study was to clarify effect of glycerol and glucose on the mechanical glass transition and dynamical transition of freeze-dried bacteria at various water activity (aw)-conditions. From the water sorption isotherm, it was noted that the water content at each aw and monolayer water content were higher in the order of glycerol, glucose, non-added samples. Effect of temperature on the mean square displacement (MSD) of atoms in the samples was investigated by incoherent elastic neutron scattering. The MSD increased gradually with an increase in temperature depending on the aw and added solute. From the linear fitting, three dynamical transition temperatures (low-, middle- and high-Tds) were determined. The Couchman-Karasz model suggested that the added solute and bacteria were not completely miscible.

Generalized extreme value analysis of efficient evaluation of extreme values in random media criticality calculations

Ueki, Taro

Progress in Nuclear Energy, 173, p.105236_1 - 105236_10, 2024/08

https://doi.org/10.1016/j.pnucene.2024.105236

The theme of this paper is how to efficiently analyse extreme realizations of neutron effective multiplication factor (keff) over random media replicas modelled by incomplete randomized Weierstrass function (IRWF). To this end, a new bounded amplification (BA) technique is applied to IRWF. Numerical results indicate that the BA-applied IRWF reduces a required number of random media replicas at least by an order of magnitude. To validate this efficiency gain, generalized extreme value (GEV) analysis is applied to a data set of keff values obtained without applying BA. It turns out that the extreme values of these keff values follow the Weibull distribution. Therefore, the theory of GEV guarantees the existence of the upper limit of these keff values, and the actually computed upper limit is indeed smaller than the top two keff values obtained from an order-of magnitude reduced number of BA-applied IRWF random media replicas. This means that the efficiency gain via BA has been confirmed by GEV analysis.

Polyelectrolyte-protein synergism; pH-responsive polyelectrolyte/insulin complexes as versatile carriers for targeted protein and drug delivery

Murmiliuk, A.*; Iwase, Hiroki*; Kang, J.-J.*; Mohanakumar, S.*; Appavou, M.-S.*; Wood, K.*; Almsy, L.*; Len, A.*; Schwrzer, K.*; Allgaier, J.*; et al.

Journal of Colloid and Interface Science, 665, p.801 - 813, 2024/07

https://doi.org/10.1016/j.jcis.2024.03.156

The complexity of protein structure limits our ability to predict and tune the properties of the formed nanoparticles. The goal of our research is to elucidate the key triggers of the morphological transition in protein/PE complexes, evaluate their encapsulation efficacy, and assess particle stability by the systematic study of complexes formed by block copolymers with proteins and ionic drugs. We demonstrated that copolymers consisting of PE and neutral hydrophilic block co-assemble with insulin at pH values close to the protein isoelectric point. The insulin arrangement within the particle is controlled by electrostatic forces between protein molecules, and the morphology of the formed particles can be tuned by varying pH and ionic strength.

Detailed visualization of radioactive hotspots inside the Unit 1 reactor building of the Fukushima Daiichi Nuclear Power Station using an integrated Radiation Imaging System mounted on a Mecanum wheel robot

Sato, Yuki; Terasaka, Yuta; Oura, Masatoshi*

Journal of Nuclear Science and Technology, 61(7), p.856 - 870, 2024/07

https://doi.org/10.1080/00223131.2023.2282551

A Mechanism for spontaneous thermal fragmentation with coolant entrainment during the molten fuel-sodium interaction

Johnson, M.*; Emura, Yuki; Clavier, R.*; Matsuba, Kenichi; Kamiyama, Kenji; Brayer, C.*; Journeau, C.*

Nuclear Engineering and Design, 423, p.113165_1 - 113165_14, 2024/07

https://doi.org/10.1016/j.nucengdes.2024.113165

Experimental investigation of two interactions between molten jets and sodium, pertaining to severe accidents in a sodium-cooled fast reactor, have been undertaken at the JAEA's MELT facility. X-ray imaging and debris analysis reveal rapid formation of a crust at the melt coolant-interface, instigating thermal fragmentation events. Heat transfer calculations at the jet-coolant interface, supported by particle tracking velocimetry characterisation of the jet velocity, imply the formation of a solid crust within milliseconds of contact with the coolant. A mechanism for enhanced thermal fragmentation is proposed, inspired by observations from the X-ray imaging of coolant entrainment into the jet.

Ultrasound-assisted removal of contaminants on stainless steel surfaces using nitrogen ultrafine bubble water

Nakahara, Masaumi; Watanabe, So; Kimura, Shuya; Sasaki, Misa*; Inagaki, Hiromitsu*; Moriguchi, Tetsuji*

Progress in Nuclear Energy, 172, p.105195_1 - 105195_8, 2024/07

https://doi.org/10.1016/j.pnucene.2024.105195

A novel removal technique with ultrafine bubbles has been proposed for decommissioning of nuclear facilities. The performance of removal technology with ultrafine bubbles was evaluated in the removal experiments with non-radioactive materials, simulated contaminants precipitated Co oxides. To investigate the influence of difference in the chemical forms, the decontamination experiments were carried out with the fuel pin end plugs contaminated radioactive materials in a hot cell.