Radiolytic stability of the TEHDGA-impregnated silica-based adsorbent for extraction chromatography

Miyazaki, Yasunori; Sano, Yuichi; Ishigami, Ryoya*

EPJ Web of Conferences, 317, p.01006_1 - 01006_7, 2025/01

https://doi.org/10.1051/epjconf/202531701006

The gamma-ray and He ion beam (which is simulated for alpha-ray from Am, for example) were irradiated on the TEHDGA adsorbent to evaluate the hydrogen gas production, leaching amount of organics in the immersed 3 M HNO solution, thermal characteristics and speciation of the degradation products. These were combined to assess the safety of the 1st run of the MA separation process from the raffinate at a dose rate of 1 kGy/h.

Implementation of track length estimator for flux distribution tallies using proper orthogonal decomposition in one-dimensional geometry

Kondo, Ryoichi; Endo, Tomohiro*; Yamamoto, Akio*

EPJ Web of Conferences, 302, p.04002_1 - 04002_10, 2024/10

https://doi.org/10.1051/epjconf/202430204002

In the recent study, we have developed an efficient flux distribution tallying method in the Monte Carlo calculation toward the high-fidelity, large scale multi-physics simulation. In this method, the proper orthogonal decomposition is applied to the flux distribution tallies. While the tallying method was implemented with the collision estimator in the previous study, the track length estimator is implemented in the present study to obtain the tally with lower statistical error. The implementation of the flux distribution tally with the track length estimator is compared with that of the collision estimator and the normal track length estimator in a one-dimensional problem. The numerical results reveal that the distribution tally using the POD with the track length estimator can obtain a more precise solution compared with that with the collision estimator. Therefore, in terms of the statistical error, the relationship between the distribution tally with track length and collision estimator is similar to that between the conventional track length and collision estimators.

Gas entrainment simulation for fast reactors using freesurface lattice Boltzmann method

Sitompul, Y.; Sugihara, Kenta; Onodera, Naoyuki; Idomura, Yasuhiro

EPJ Web of Conferences, 302, p.05004_1 - 05004_10, 2024/10

https://doi.org/10.1051/epjconf/202430205004

In fast reactor designs, it is of critical importance to avoid gas entrainment phenomena due to free-surface vortices. Numerical analysis is one of the key methods to understand these phenomena. However, the challenges in computational efficiency and accuracy of the previous numerical methods lead to exploring the Lattice Boltzmann method (LBM) as an alternative, known for its computational efficiency and capability in simulating complex flows. In this study, we implement free-surface LBM to accelerate gas entrainment analysis, significantly reducing computational costs while maintaining accuracy compared to traditional methods. Simulation results using LBM align well with experimental data, offering a promising avenue for faster analysis in future fast reactor designs.

Selection method for observation points using Bayesian LASSO at estimating radiation source distribution from air dose rates

Yamada, Susumu; Machida, Masahiko; Tanimura, Naoki*

EPJ Web of Conferences, 302, p.16004_1 - 16004_10, 2024/10

https://doi.org/10.1051/epjconf/202430216004

When we decommission a reactor building, it is desirable to identify the radiation source distribution for safety. It has been reported that the source distribution can be estimated from the measured air dose rates at appropriate observation points by minimizing an evaluation function using the Least Absolute Shrinkage and Selection Operator (LASSO). However, it is difficult to decide on suitable points in advance. Therefore, we estimate the posterior distribution from the prior distribution of the source amounts, which are calculated by the standard LASSO, using the Bayesian LASSO, and evaluate the predictive distribution of the evaluated air dose rates at the candidate observation points from the posterior distribution. We select the additional observation point based on the variances of the predictive distributions. We confirmed that the method can estimate the source distribution with fewer additional observation points than when adding ones randomly in most cases.

Total and double differential scattering cross-section measurements of isotropic graphite

Kimura, Atsushi; Endo, Shunsuke; Nakamura, Shoji

EPJ Web of Conferences, 294, p.01002_1 - 01002_7, 2024/04

https://doi.org/10.1051/epjconf/202429401002

The meson in nuclear matter from theory and experimental data

Gubler, P.; Bratkovskaya, E.*; Ichikawa, Masaya; Song, T.*

EPJ Web of Conferences, 291, p.04003_1 - 04003_4, 2024/02

https://doi.org/10.1051/epjconf/202429104003

no abstracts in English

Outcomes of WPEC SG47 on "Use of Shielding Integral Benchmark Archive and Database for Nuclear Data Validation"

Kodeli, I. A.*; Fleming, M.*; Cabellos, O.*; Leal, L.*; Celik, Y.*; Ding, Y.*; Jansky, B.*; Neudecker, D.*; Novak, E.*; Simakov, S.*; et al.

EPJ Web of Conferences, 284, p.15002_1 - 15002_8, 2023/05

https://doi.org/10.1051/epjconf/202328415002

Working Party on International Nuclear Data Evaluation Co-operation Subgroup 47 (WPEC SG47) entitled "Use of Shielding Integral Benchmark Archive and Database for Nuclear Data Validation" was started in June 2019 with the objectives to promote more systematic and wider use of shielding benchmark experiments in nuclear data and transport code validation and development, to provide feedback on the Shielding Integral Benchmark Archive and Database (SINBAD). Complementing the database with new features was discussed, for example providing the nuclear data sensitivity profiles more systematically would facilitate and better guide the use of data, and the information on the geometry, (radiation source) and materials is expected to allow an easier and less error prone computational model preparation for different transport codes. Examples of the use and some views on future development of the SINBAD benchmark database will be presented in the paper.

Measurement of displacement cross-sections of Nb irradiated by protons with kinetic energy range between 0.4 and 3 GeV

Meigo, Shinichiro; Nakano, Keita*; Matsuda, Hiroki; Iwamoto, Yosuke; Yoshida, Makoto*

EPJ Web of Conferences, 284, p.05001_1 - 05001_4, 2023/05

https://doi.org/10.1051/epjconf/202328405001

In high-intensity proton accelerator facilities such as Accelerator Driven System (ADS) and the spallation neutron source, it is crucial to evaluate the damage of beam-interception materials and accelerator components, such as a magnet coil. The displacement per atom (dpa) is used as a damage index, which is derived by integrating the particle flux and the displacement cross section based on the NRT model. Although the dpa is employed as the standard, the experimental data of displacement cross section are scarce for a proton in the energy region above 20 MeV. To obtain the data for superconducting materials for high-intensity accelerators and magnets, the displacement cross section of Nb for proton irradiation with a kinetic energy range between 0.4 and 3 GeV was measured. For sustaining damage in the sample, the Nb sample was cooled at a cryogenic temperature (8 K), where the recombination of Frenkel pairs due to thermal motion was well suppressed with maintaining the normal conductivity to maintain Matthiessen's rule. The displacement cross section of Nb was calculated using the PHITS code, and was compared with the present experimental results. It was found that the widely utilized NRT model overestimates the cross section by a factor of 2, as suggested by the previous works. It was also found that the calculation with a recently proposed athermal recombination corrected (arc) model based on Molecular Dynamics (MD) shows good agreement with the present data.

Neutron production in the interaction of 200-MeV deuterons with Li, Be, C, Al, Cu, Nb, In, Ta, and Au

Watanabe, Yukinobu*; Sadamatsu, Hiroki*; Araki, Shohei; Nakano, Keita; Kawase, Shoichiro*; Kin, Tadahiro*; Iwamoto, Yosuke; Satoh, Daiki; Hagiwara, Masayuki*; Yashima, Hiroshi*; et al.

EPJ Web of Conferences, 284, p.01041_1 - 01041_4, 2023/05

https://doi.org/10.1051/epjconf/202328401041

Intensive fast neutron sources using deuteron accelerators have been proposed for the study of medical RI production, radiation damage for fusion reactor materials, nuclear transmutation of radioactive waste, and so on. Neutron production data from various materials bombarded by deuterons are required for the design of such neutron sources. In the present work, we have conducted a systematic measurement of double-differential neutron production cross sections (DDXs) for a wide atomic number range of targets (Li, Be, C, Al, Cu, Nb, In, Ta, and Au) at an incident energy of 200 MeV in the Research Center for Nuclear Physics (RCNP), Osaka University. A deuteron beam accelerated to 200 MeV was transported to the neutron experimental hall and focused on a thin target foil. Emitted neutrons from the target were detected by two different-size EJ301 liquid organic scintillators located at two distances of 7 m and 20 m, respectively. The neutron DDXs were measured at six angles from 0 to 25). The neutron energy was determined by a conventional time-of-flight (TOF) method. The measured DDXs were compared with theoretical model calculations by the DEUteron-induced Reaction Analysis Code System (DEURACS) and PHITS. The result indicated that the DEURACS calculation provides better agreement with the measured DDXs than the PHITS calculation.

Simultaneous evaluation of uranium and plutonium fast neutron fission cross sections up to 200 MeV for JENDL-5 and its updates

Otsuka, Naohiko*; Iwamoto, Osamu

EPJ Web of Conferences, 284, p.08011_1 - 08011_4, 2023/05

https://doi.org/10.1051/epjconf/202328408011