Uncertainty reduction of the FPs transport mechanism and debris degradation behavior and evaluation of the reactor contamination of debris state on the basis of the accident progression scenario of Fukushima Daiichi Nuclear Power Station Unit 2 and 3 (Contract research); FY2021 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Tokyo Institute of Technology*

JAEA-Review 2022-053, 89 Pages, 2023/02

JAEA-Review-2022-053.pdf:3.47MB

The Collaborative Laboratories for Advanced Decommissioning Science (CLADS), Japan Atomic Energy Agency (JAEA), had been conducting the Nuclear Energy Science & Technology and Human Resource Development Project (hereafter referred to "the Project") in FY2021. The Project aims to contribute to solving problems in the nuclear energy field represented by the decommissioning of the Fukushima Daiichi Nuclear Power Station, Tokyo Electric Power Company Holdings, Inc. (TEPCO). For this purpose, intelligence was collected from all over the world, and basic research and human resource development were promoted by closely integrating/collaborating knowledge and experiences in various fields beyond the barrier of conventional organizations and research fields. The sponsor of the Project was moved from the Ministry of Education, Culture, Sports, Science and Technology to JAEA since the newly adopted proposals in FY2018. On this occasion, JAEA constructed a new research system where JAEA-academia collaboration is reinforced and medium-to-long term research/development and human resource development contributing to the decommissioning are stably and consecutively implemented. Among the adopted proposals in FY2021, this report summarizes the research results of the "Uncertainty reduction of the FPs transport mechanism and debris degradation behavior and evaluation of the reactor contamination of debris state on the basis of the accident progression scenario of Fukushima Daiichi Nuclear Power Station Unit 2 and 3" conducted in FY2021. The present study aims to elucidate the cause of the high dosage under shield plug by clarification of to the cesium behavior of migration, adhesion to structure and deposition as well as evaluate the properties of metal-rich debris predeceasing melted through the materials science approach based on the most probable scenario of accident progression of Unit 2 and 3. In this fiscal year, the followings were achieved.

Radiation imaging system using a compact -ray imager mounted on a remotely operated machine

Sato, Yuki; Kawabata, Kuniaki; Ozawa, Shingo*; Izumi, Ryo*; Kaburagi, Masaaki; Tanifuji, Yuta; Terasaka, Yuta; Miyamura, Hiroko; Kawamura, Takuma; Suzuki, Toshikazu*; et al.

IFAC-PapersOnLine, 50(1), p.1062 - 1066, 2017/07

https://doi.org/10.1016/j.ifacol.2017.08.218

DNP of free-radical-doped and e-beam irradiated samples for spin contrast variation study

Kumada, Takayuki; Noda, Yohei*; Ishikawa, Norito

no journal, , 

We compared dynamic nuclear polarization (DNP) behavior of electron-beam irradiated and TEMPO-doped polymers. Growth and decay rates of nuclear polarization of e-PE increased linearly with increasing radical concentration, whereas those of T-PS increased with square of the radical concentration. From these results, we suggest that the pair of alkyl radicals produced by the radiolysis and the subsequent hydrogen abstraction reaction in e-PE plays an important role on DNP, whereas T-PS is polarized by a pair of unspecified TEMPO accidentally located nearby. We propose that higher polarization would be expected by optimizing the inter-radical distance within the pair in e-PE and other irradiated samples.

Progress of 1F PCV contaminant analysis by TEM observation

Suzuki, Akihiro*; Kitsunai, Yuji*; Sato, Ikken

no journal, , 

Several contaminant samples from 1F1 primary containment vessel are carefully observed by transmission electron microscope to find micro-scale uranium-containing particles in their chemical forms of U-rich c-(U,Zr)O and Zr-rich t-(Zr,U)O, which are also observed in fuel debris of TMI-2 and Chernobyl NPP-4.