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JAEA Reports

Survey on the radioactive substance in the coastal areas near Fukushima Prefecture in FY2019 (Contract research)

Misono, Toshiharu; Tsuruta, Tadahiko; Nakanishi, Takahiro; Sanada, Yukihisa; Shiribiki, Takehiko; Miyamoto, Kenji*; Urabe, Yoshimi*

JAEA-Research 2020-008, 166 Pages, 2020/10

JAEA-Research-2020-008.pdf:13.11MB
JAEA-Research-2020-008(errata).pdf:0.92MB

After the accident at TEPCO Fukushima Daiichi Nuclear Power Station (1F), marine monitoring survey on radioactive substances have been conducted with financially supported by the Nuclear Regulatory Agency from FY2019. Results obtain in the project in FY2019 are presented in this report. Based on scientific grounds, the concept necessary for "progress of sea area monitoring" was arranged for the future medium- to long-term investigation of radiocesium concentrations. As basic information of survey frequency revise, a seabed topography and sediment distribution survey was conducted, and an attempt was made to understand the relationship between the seabed topography and the grain size distribution of bottom sediment. A columnar core sample was collected in the coastal area and analyzed for radioactive cesium concentration. In order to understand the dynamics of radioactive cesium contained in suspended matter flowing in from a river, suspended solids was collected using a sediment trap and the concentration of radioactive cesium was measured. We re-analyzed the towed monitoring data that had been implemented since 2013, and tried to improve the accuracy of the radioactive cesium distribution estimation map in the coastal area.

Journal Articles

Research and development on lead-bismuth technology for accelerator-driven transmutation system at JAERI

Kurata, Yuji; Kikuchi, Kenji; Saito, Shigeru; Kamata, Kinya*; Kitano, Teruaki*; Oigawa, Hiroyuki

Proceedings of 4th International Workshop on the Utilisation and Reliability of High Power Proton Accelerators, p.267 - 277, 2004/05

R&D on lead-bismuth technology have been conducted for accelerator driven system. From the test results of 316SS using JLBL-1 for 3000h without active oxygen control, mass transfer from high temperature to low temperature parts was observed. It was found that deposition of Pb/Bi and Fe-Cr grains in the annular channel of the electro-magnetic pump caused plugging and decrease in flow rate. The modification of the loop system brought about a good effect on operation. Significant erosion/corrosion was not observed in the experiment using MES loop for 1000h under 10 $^{-5}$ wt.% oxygen condition. The results of static corrosion tests showed the following: corrosion depth decreased at 450 $^{circ}$ C with increasing Cr content in steels while corrosion depth of JPCA and 316SS became larger due to ferritization caused by dissolution of Ni and Cr at 550 $^{circ}$ C. Si-added steel exhibited good corrosion resistance at 550 $^{circ}$ C.