R&D of digital technology on inverse estimation of radioactive source distributions and related source countermeasures; R&D status of digital platform including 3D-ADRES-indoor

Machida, Masahiko; Yamada, Susumu; Kim, M.; Okumura, Masahiko; Miyamura, Hiroko; Shikaze, Yoshiaki; Sato, Tomoki*; Numata, Yoshiaki*; Tobita, Yasuhiro*; Yamaguchi, Takashi; et al.

RIST News, (69), p.2 - 18, 2023/09

https://www.rist.or.jp/rnews/69/69s2.pdf

The contamination of radioactive materials leaked from the reactor has resulted in numerous hot spots in the Fukushima Daiichi Nuclear Power Station (1F) building, posing obstacles to its decommissioning. In order to solve this problem, JAEA has conducted research and development of the digital technique for inverse estimation of radiation source distribution and countermeasures against the estimated source in virtual space for two years from 2021 based on the subsidy program "Project of Decommissioning and Contaminated Water Management" performed by the funds from the Ministry of Economy, Trade and Industry. In this article, we introduce the results of the project and the plan of the renewal project started in April 2023. For the former project, we report the derivative method for LASSO method considering the complex structure inside the building and the character of the source and show the result of the inverse estimation using the method in the real reactor building. Moreover, we explain the platform software "3D-ADRES-Indoor" which integrates these achievements. Finally, we introduce the plan of the latter project.

Translational study for stereotactic body radiotherapy against non-small cell lung cancer, including oligometastases, considering cancer stem-like cells enable predicting clinical outcome from data

Saga, Ryo*; Matsuya, Yusuke; Sato, Hikari*; Hasegawa, Kazuki*; Obara, Hideki*; Komai, Fumio*; Yoshino, Hironori*; Aoki, Masahiko*; Hosokawa, Yoichiro*

Radiotherapy and Oncology, p.109444_1 - 109444_9, 2023/00

https://doi.org/10.1016/j.radonc.2022.109444

When treating non-small cell lung cancer (NSCLC), stereotactic body radiotherapy (SBRT) with high-dose irradiation is often utilized. The fractionation schemes and curative effects can be evaluated by mathematical models for predicting cell survival curve. Such model parameters can be determined from in vitro experiment, but they are empirically determined based on experiences in clinics. As such, there is a large gap between in vitro and clinical study. As such background, translational study between in vitro cell survival and clinical curative effects is necessary. In this study, explicitly considering existence of cancer stem-like cells (CSCs), we developed an all-in-one model for predicting both in vitro cell survival and clinical curative effects (integrated microdosimetric-kinetic (IMK) model) and performed retrospective evaluation of clinical outcomes following SBRT for NSCLC in Hirosaki University Hospital. As a result, the IMK model successfully reproduced both in vitro cell survival and the tumor control probability with various fractionation schemes (i.e., 6-10 Gy per fraction). The developed model would contribute on precisely understanding the impact of CSCs on curative effects after SBRT for NSCLC with high precision.

Experimental study on transport behavior of cesium iodide in the reactor coolant system under LWR severe accident conditions

Miyahara, Naoya; Miwa, Shuhei; Goullo, M.*; Imoto, Jumpei; Horiguchi, Naoki; Sato, Isamu*; Osaka, Masahiko

Journal of Nuclear Science and Technology, 57(12), p.1287 - 1296, 2020/12

https://doi.org/10.1080/00223131.2020.1782281

In order to clarify the cesium iodide (CsI) transport behavior with a focus on the mechanisms of gaseous iodine formation in the reactor coolant system of LWR under a severe accident condition, a reproductive experiment of CsI transport behavior was conducted using a facility equipped with a thermal gradient tube. Various analyses on deposits and airborne materials during transportation could elucidate two mechanisms for the gaseous iodine formation. One was the gaseous phase chemical reaction in Cs-I-O-H system at relatively high-temperature region, which led to gaseous iodine transport to the lower temperature region without any further changes in gas species due to the kinetics limitation effects. The other one was the chemical reactions related to condensed phase of CsI, namely those of CsI deposits on walls with surface of stainless steel to form CsCrO compound and CsI aerosol particles with steam, which were newly found in this study.

Localization of cesium on montmorillonite surface investigated by frequency modulation atomic force microscopy

Araki, Yuki*; Sato, Hisao*; Okumura, Masahiko; Onishi, Hiroshi*

Surface Science, 665, p.32 - 36, 2017/11

https://doi.org/10.1016/j.susc.2017.08.004

no abstracts in English

Progress report of Japanese simulation research projects using the high-performance computer system Helios in the International Fusion Energy Research Centre

Ishizawa, Akihiro*; Idomura, Yasuhiro; Imadera, Kenji*; Kasuya, Naohiro*; Kanno, Ryutaro*; Satake, Shinsuke*; Tatsuno, Tomoya*; Nakata, Motoki*; Nunami, Masanori*; Maeyama, Shinya*; et al.

Purazuma, Kaku Yugo Gakkai-Shi, 92(3), p.157 - 210, 2016/03

http://www.jspf.or.jp/Journal/PDF_JSPF/jspf2016_03/jspf2016_03-157.pdf

The high-performance computer system Helios which is located at The Computational Simulation Centre (CSC) in The International Fusion Energy Research Centre (IFERC) started its operation in January 2012 under the Broader Approach (BA) agreement between Japan and the EU. The Helios system has been used for magnetised fusion related simulation studies in the EU and Japan and has kept high average usage rate. As a result, the Helios system has contributed to many research products in a wide range of research areas from core plasma physics to reactor material and reactor engineering. This project review gives a short catalogue of domestic simulation research projects. First, we outline the IFERC-CSC project. After that, shown are objectives of the research projects, numerical schemes used in simulation codes, obtained results and necessary computations in future.

Phonons of Fe-based superconductor CaPtAs(FePtAs)

Ikeuchi, Kazuhiko*; Kobayashi, Yoshiaki*; Suzukia, Kazunori*; Ito, Masayuki*; Kajimoto, Ryoichi; Bourges, P.*; Christianson, A. D.*; Nakamura, Hiroki; Machida, Masahiko; Sato, Masatoshi*

Journal of Physics; Condensed Matter, 27(46), p.465701_1 - 465701_7, 2015/11

https://doi.org/10.1088/0953-8984/27/46/465701

We report the results of inelastic neutron scattering measurements on particular phonons of a superconducting (SC) CaPtAs(FePtAs) with the onset transition temperature K to investigate mainly what roles orbital fluctuation plays in Cooper pairing, where we observed a slight softening of the in-plane transverse acoustic mode corresponding to the elastic constant . This softening starts at temperature well above the SC , as decreases. An anomalously strong change of the scattering intensity of in-plane optical modes was observed at the M point of the pseudo tetragonal reciprocal space in the range of 35 40 meV with decreasing from far above . Because this region mainly corresponds to the motion of Fe and As atoms in the FeAs planes, the finding presents information on the coupling between the orbital fluctuation of Fe electrons and the lattice system, useful for studying the possible roles of orbital fluctuation in the pairing mechanism and/or the appearance of the so-called nematic phase.

Measurement of hydrogen generating from radiolysis of highly active liquid waste and its quantitative evaluation

Yamamoto, Masahiko; Surugaya, Naoki; Mori, Eito; Taguchi, Shigeo; Sato, Soichi

JAEA-Research 2015-013, 27 Pages, 2015/10

JAEA-Research-2015-013.pdf:2.84MB

The H concentration generating from Highly Active Liquid Waste (HALW) of Tokai Reprocessing Plant is measured in a closed experimental system. The experimental results show that H concentration gradually increases at first and then approaches a steady-state due to the H consumption reaction by Pd ions. The highest H concentration is 1200 ppm (0.1%) when the solution temperature is at 23C. It is found that H generating from HALW is equilibrated one order of magnitude lower than the H combustion lower limit. Moreover, a model based on H generation from HALW by the radiolysis and H consumption reaction by Pd ions is proposed and applied to evaluate H concentration behavior in the gas phase. The calculated H concentrations from proposed model agreed well with the experimental values. It is demonstrated that the behavior of H generating from HALW can be evaluated quantitatively by applying the proposed model in this study.

Evaluation of plutonium(IV) extraction rate between nitric acid and tri--butylphosphate solution using a glass chip microchannel

Yamamoto, Masahiko; Taguchi, Shigeo; Sato, Soichi; Surugaya, Naoki

Journal of Separation Science, 38(10), p.1807 - 1812, 2015/05

https://doi.org/10.1002/jssc.201401315

The extraction of Pu with tri--butyl phosphate (TBP) is performed using a glass microchip to evaluate the extraction rate. The parallel two-phase laminar flow is constructed in a microchannel by introducing plutonium nitrate solution and TBP diluted with -dodecane as aqueous and organic phase, respectively. It was found that extraction ratio of Pu increases with increasing the contact time of two phases. A numerical model based on the diffusion in the microchannel and the reaction at the interface was incorporated to evaluate the extraction rate. The experimental data points were subjected to least-squares fitting and the forward extraction rate of Pu(IV) was determined.

Mathematical Modeling of Radioactive Contaminants in the Fukushima Environment

Kitamura, Akihiro; Kurikami, Hiroshi; Yamaguchi, Masaaki; Oda, Yoshihiro; Saito, Tatsuo; Kato, Tomoko; Niizato, Tadafumi; Iijima, Kazuki; Sato, Haruo; Yui, Mikazu; et al.

Nuclear Science and Engineering, 179(1), p.104 - 118, 2015/01

https://doi.org/10.13182/NSE13-89

The prediction of the distribution and fate of radioactive materials eventually deposited at surface in the Fukushima area is one of the main objectives and expected to be achieved in an efficient manner. In order to make such prediction, a number of mathematical models of radioactive contaminants, with particular attention on cesium, on the land and in rivers, lakes, and estuaries in the Fukushima area are developed. Simulation results are examined with the field investigations simultaneously implemented. The basic studies of the adsorption/absorption mechanism of cesium and soils have been performed to shed light on estimating distribution coefficient between dissolved contaminant and particulate contaminant.

Distribution of radioactive nuclides of boring core samples extracted from concrete structures of reactor buildings in the Fukushima Daiichi Nuclear Power Plant

Maeda, Koji; Sasaki, Shinji; Kumai, Misaki; Sato, Isamu; Suto, Mitsuo; Osaka, Masahiko; Goto, Tetsuo*; Sakai, Hitoshi*; Chigira, Takayuki*; Murata, Hirotoshi*

Journal of Nuclear Science and Technology, 51(7-8), p.1006 - 1023, 2014/07

https://doi.org/10.1080/00223131.2014.915769

Since the start of the severe accident at the Fukushima Daiichi Nuclear Power Plant in March 2011, concrete surfaces within the reactor buildings have been exposed to radioactive contaminants. Released radiation sources still remain too high to permit entry into some areas of the RBs to allow the damage to be assessed and to allow carrying out the restoration of lost safety functions, decommissioning activities, etc. In order to clarify the situation of this contamination in the RBs, 18 samples were subjected to analyses to determine the surface radionuclide concentrations and to characterize the radionuclide distributions in the samples. Decontamination tests on the sample of Unit 2 were conducted to reduce the levels of radioactivity present near the sample surface. As a result of the tests, the level of radioactivity of the sample was reduced with the removal of 97% of the contamination present near the sample surface.