Validating terrestrial SER in 12-, 28-, and 65-nm SRAMs estimated by simulation coupled with one-time neutron irradiation

Takami, Kazusa*; Gomi, Yuibi*; Yasuda, Ryuichi*; Abe, Shinichiro; Ito, Masatoshi*; Kanda, Hiroki*; Fukuda, Mitsuhiro*; Hashimoto, Masanori*

IEEE Transactions on Nuclear Science, 72(8), p.2622 - 2628, 2025/08

https://doi.org/10.1109/TNS.2025.3534564

Neutron-induced soft errors in the terrestrial environment pose reliability issues for semiconductor devices. We have developed the new method for estimating terrestrial SER based on simulation coupled with one-time irradiation using a conventional neutron source. This method has been validated using 65-nm planar SRAMs. However, with the ongoing progression of process shrinkage and the increasing adoption of devices fabricated with newer processes, there is a growing demand for further experimental validation of the terrestrial SER estimation method for these advanced processes. In this work, we validated the estimation method for 12-nm 1-fin FinFETs and 28-nm planer SRAMs. The SERs estimated by our method were consistent with the SERs measured using a white neutron beam at RCNP within 28% error.

Evaluating the effect of temporal variations in wind speed on sheltering effectiveness and developing a simplified correction method to account for these variations

Hirouchi, Jun; Takahara, Shogo; Watanabe, Masatoshi*

Journal of Radiological Protection, 45(2), p.021506_1 - 021506_13, 2025/05

https://doi.org/10.1088/1361-6498/add53e

Sheltering is a key countermeasure for mitigating radiation exposures during nuclear power plant accidents. The effectiveness of sheltering in minimizing inhalation exposure is commonly expressed using the reduction factor, which is the ratio of indoor to outdoor cumulative doses. The indoor dose is primarily influenced by the air exchange rate, penetration factor, and indoor deposition rate. Additionally, the air exchange rate is dependent on wind speed. In previous studies, the reduction factor was often treated as a constant value or calculated under constant wind speed conditions. However, wind speed varies in reality. This study investigated the effect of temporal variations in wind speed on the reduction factor and developed a simplified correction method to account for these variations. The results revealed that temporal variations in wind speed caused the reduction factor to differ by a factor of approximately two. Using the simplified correction method, the corrected reduction factors agreed, on average, within 10% of those calculated using a method that explicitly considers temporal variations in actual wind speed. Additionally, the computational cost was reduced by more than 20 times.

Effects of different accident scenarios and sites on the reduction factor used for expressing sheltering effectiveness

Hirouchi, Jun; Watanabe, Masatoshi*; Hayashi, Naho; Nagakubo, Azusa; Takahara, Shogo

Journal of Radiological Protection, 45(1), p.011506_1 - 011506_11, 2025/03

https://doi.org/10.1088/1361-6498/adba6e

Public living in areas contaminated by nuclear accidents is exposed to radiation in the early phase and over the long term. Even under similar accident scenarios, radiation doses and sheltering effectiveness, which is one of the protective measures, depend on meteorological conditions and the surrounding environment. Radiation doses and sheltering effectiveness in the early phase of nuclear accidents are crucial information for the public as well as national and local governments planning a nuclear emergency preparedness. In this study, we assessed radiation doses and sheltering effectiveness at sites with nuclear facilities in Japan using the Off-Site Consequence Analysis code for Atmospheric Release accidents, which is one of the level-3 probabilistic risk assessment codes, for five accident scenarios: three scenarios from past severe accident studies, a scenario defined by the Nuclear Regulation Authority in Japan, and a scenario corresponding to the Fukushima-Daiichi Nuclear Power Station accident. The sheltering effectiveness differed by up to approximately 50% among the accident scenarios at the same sites and by approximately 20%50% among sites under the same accident scenario. Differences in the radionuclide composition among the accident scenarios and the differences in wind speeds among the sites primarily caused these differences in sheltering effectiveness.

Decommissioning report for Wastewater Treatment Facility (Part 2); Chapter on contamination inspection section

Yamamoto, Keisuke; Nakagawa, Takuya; Shimojo, Hiroto; Kijima, Jun; Miura, Daiya; Onose, Yoshihiko*; Namba, Koji*; Uchida, Hiroaki*; Sakamoto, Kazuhiko*; Ono, Chika*; et al.

JAEA-Technology 2024-019, 211 Pages, 2025/02

JAEA-Technology-2024-019.pdf:35.35MB

The uranium enrichment facilities at the Nuclear Fuel Cycle Engineering Laboratories of Japan Atomic Energy Agency (JAEA) were constructed sequentially to develop uranium enrichment technology with centrifugal separation method. The developed technologies were transferred to Japan Nuclear Fuel Limited until 2001. And the original purpose has been achieved. Wastewater Treatment Facility, one of the uranium enrichment facilities, was constructed in 1976 to treat radioactive liquid waste generated at the facilities, and it finished the role in 2008. In accordance with the Medium/Long-Term Management Plan of JAEA Facilities, interior equipment installed in this facility had been dismantled and removed since November 2021 to August 2023. This report summarizes the findings obtained through the work related to the contamination inspection methods cancellation the controlled area of Wastewater Treatment Facility from September 2023 to March 2024.

Resonance ionization spectroscopy of neodymium for determining a highly efficient two-step ionization scheme

Miyabe, Masabumi; Iwata, Yoshihiro; Tomita, Hideki*; Morita, Masato*; Sakamoto, Tetsuo*

Spectrochimica Acta, Part B, 221, p.107036_1 - 107036_12, 2024/11

https://doi.org/10.1016/j.sab.2024.107036

Two-color two-step resonance ionization spectroscopy of neodymium (Nd) was performed to identify more than 120 even-parity autoionizing levels and their candidate J-values. The analysis of the observed autoionizing Rydberg series yielded a value of 44560.11 (43)(2) cm as a more accurate ionization potential of Nd. The saturation method was used to measure the transition cross-sections for some intense ionization transitions. From the measured cross-sections, the ionization efficiencies of some two-step ionization schemes were evaluated using the scheme cross-section formula to obtain several promising schemes.

France-Japan collaboration on severe accident studies in sodium-cooled fast reactors, 2; Methodologies and calculations of severe accident phases

Sogabe, Joji; Ishida, Shinya; Tagami, Hirotaka; Okano, Yasushi; Kamiyama, Kenji; Onoda, Yuichi; Matsuba, Kenichi; Yamano, Hidemasa; Kubo, Shigenobu; Kubota, Ryuzaburo*; et al.

Proceedings of International Conference on Nuclear Fuel Cycle (GLOBAL2024) (Internet), 4 Pages, 2024/10

In the frame of France-Japan collaboration, the calculational methodologies were defined and assessed, and the phenomenology and the severe accident consequences were investigated in a pool-type sodium-cooled fast reactor.

Research and development of three-dimensional isolation system for sodium cooled fast reactor, 7; Development summary of three-dimensional isolation system

Watakabe, Tomoyoshi; Yamamoto, Tomohiko; Okamura, Shigeki; Miyazaki, Masashi; Miyagawa, Takayuki; Uchita, Masato*; Hirayama, Tomoyuki*; Somaki, Takahiro*; Yukawa, Masaki*; Fukasawa, Tsuyoshi*; et al.

Proceedings of ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 10 Pages, 2024/07

To secure the seismic safety of the thin-walled mechanical components and piping under a severe design earthquake level, employing a three-dimensional (3D) seismic isolation system has been planned in a sodium-cooled fast reactor. The development results of the 3D isolation system have been reported in previous papers so far. Its update is reported in Part 7 to Part 9. Part 7 describes the overview of the development, the test plan of the isolation system in the assembled state of each element, and the performance of individual isolation elements. In part 8, the performance of the isolation device that each element was assembled into was investigated through loading tests. Part 9 reports analytical studies by an analysis model validated based on the insight of the test results.

Research and development of three-dimensional isolation system for sodium-cooled fast reactor, 8; Assembly static test results of three-dimensional isolated device by bi-axial loadings

Somaki, Takahiro*; Yukawa, Masaki*; Fukasawa, Tsuyoshi*; Hirayama, Tomoyuki*; Uchita, Masato*; Miyagawa, Takayuki; Okamura, Shigeki; Yamamoto, Tomohiko; Watakabe, Tomoyoshi; Miyazaki, Masashi; et al.

Proceedings of ASME 2024 Pressure Vessels & Piping Conference (PVP 2024) (Internet), 9 Pages, 2024/07

https://doi.org/10.1115/PVP2024-124495

A Science-based mixed oxide property model for developing advanced oxide nuclear fuels

Kato, Masato; Oki, Takumi; Watanabe, Masashi; Hirooka, Shun; Vauchy, R.; Ozawa, Takayuki; Uwaba, Tomoyuki; Ikusawa, Yoshihisa; Nakamura, Hiroki; Machida, Masahiko

Journal of the American Ceramic Society, 107(5), p.2998 - 3011, 2024/05

https://doi.org/10.1111/jace.19609

The Role of collision ionization of K-shell ions in nonequilibrium plasmas produced by the action of super strong, ultrashort PW-class laser pulses on micron-scale argon clusters with intensity up to 5 10 W/cm

Skobelev, I. Yu.*; Ryazantsev, S. N.*; Kulikov, R. K.*; Sedov, M. V.*; Filippov, E. D.*; Pikuz, S. A.*; Asai, Takafumi*; Kanasaki, Masato*; Yamauchi, Tomoya*; Jinno, Satoshi; et al.

Photonics (Internet), 10(11), p.1250_1 - 1250_11, 2023/11

https://doi.org/10.3390/photonics10111250

It is challenging to clearly distinguish the impacts of the optical field and collisional ionization in the evolution of the charge state of a plasma produced when matter interacts with high-intensity laser pulses. In this work, time-dependent calculations of plasma kinetics are used to show that it is possible only when low-density gaseous targets with sufficiently small clusters are used. In the case of Ar plasma, the upper limit of the cluster radius was estimated to be m.