Development of hydrogels for prevention of radioactive dust dispersion during fuel debris retrieval (Contract research); FY2019 Nuclear Energy Science & Technology and Human Resource Development Project

Collaborative Laboratories for Advanced Decommissioning Science; Osaka University*

JAEA-Review 2020-030, 55 Pages, 2020/12

JAEA-Review-2020-030.pdf:2.76MB

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 FY2019. 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 FY2018, this report summarizes the research results of the "Development of hydrogels for prevention of radioactive dust dispersion during fuel debris retrieval" conducted in FY2019. In this study, we propose coating fuel debris with thixotropic gel materials to suppress dust dispersion during debris retrieval. Hectorite clay mineral - borax composite gel was selected based on the viscosity, the transparency and the radiation resistance. Simulated cutting tests confirm that the gel coating effectively suppress the dust dispersion.

Study on Pu-burner high temperature gas-cooled reactor in Japan; Test and characterization for ZrC coating

Ueta, Shohei; Aihara, Jun; Mizuta, Naoki; Goto, Minoru; Fukaya, Yuji; Tachibana, Yukio; Okamoto, Koji*

Proceedings of 9th International Topical Meeting on High Temperature Reactor Technology (HTR 2018) (USB Flash Drive), 7 Pages, 2018/10

The security and safety fuel (3S-TRISO fuel) employs the coated fuel particle with a fuel kernel made of plutonium dioxide (PuO) and yttria stabilized zirconia (YSZ) as an inert matrix. Especially, a zirconium carbide (ZrC) coating is one of key technologies of the 3S-TRISO, which performs as an oxygen getter to reduce the fuel failure due to internal pressure during the irradiation. R&Ds on ZrC coating directly on the dummy CeO-YSZ kernel have been carried in the Japanese fiscal year 2017. As results of ZrC coating tests by the bromide chemical vapor deposition process, stoichiometric ZrC coatings with 3 - 18 microns of thicknesses were obtained with 0.1 kg of particle loading weight.

Development of silicon carbide coating on AlO ceramics from precursor polymers by radiation curing

Wach, R.; Sugimoto, Masaki; Yoshikawa, Masahito

Key Engineering Materials, 317-318, p.573 - 576, 2006/08

no abstracts in English

Development of reliable diamond window for EC launcher on fusion reactors

Takahashi, Koji; Illy, S.*; Heidinger, R.*; Kasugai, Atsushi; Minami, Ryutaro; Sakamoto, Keishi; Thumm, M.*; Imai, Tsuyoshi

Fusion Engineering and Design, 74(1-4), p.305 - 310, 2005/11

https://doi.org/10.1016/j.fusengdes.2005.06.234

A new diamond window with the copper-coated edge for an EC launcher is developed. The diamond window is designed to cool its disk edge. Since Cu is coated at the entire edge, ingress of cooling water into a transmission line in case of failure on the edge is negligible. In addition, corrosion of Al blaze between the edge and the Inconel cuffs can be avoided. A 170GHz, RF transmission experiment equivalent to a MW-level transmission was carried out to investigate the capability of the edge cooling. The transmission power and pulse are 55kW and 3sec, respectively. Temperature increase was 45C and alomost became constant. Thermal calculation with tan of 4.410 and thermal conductivity of 1.9kW/m/K agrees with the experiment. Since tan of the diamond is much higher than the actual one (tan=210), the temperature increase corresponds to that of 1MW transmission. It concludes that the Cu coating dose not degrade the edge cooling capability and improves the reliability of the diamond window.

An Irradiation experiment for qualification of insulating coating

Nakamichi, Masaru*; Kawamura, Hiroshi

JAERI-Research 2005-015, 35 Pages, 2005/06

JAERI-Research-2005-015.pdf:6.48MB

no abstracts in English

Solid spallation target materials development

Kawai, Masayoshi*; Furusaka, Michihiro; Li, J.-F.*; Kawasaki, Akira*; Yamamura, Tsutomu*; Mehmood, M.*; Kurishita, Hiroaki*; Kikuchi, Kenji; Takenaka, Nobuyuki*; Kiyanagi, Yoshiaki*; et al.

Proceedings of ICANS-XVI, Volume 3, p.1087 - 1096, 2003/07

In order to establish the technique fabricating a thin target slab with a real size, thin tantalum-clad tungsten slab with a hole for a thermocouple was fabricated with the high-precision machinery techniques and the HIP'ing method. The ultrasonic diagnostic showed that tantalum and tungsten bond was perfect. The HIP optimum condition was certified by means of the small punch test as already reported. The electrolytic coating technique in a molten salt was developed to make a thinner tantalum cladding on a tungsten target with a complicated shape, in order to reduce radioactivity from tantalum in an irradiated target.

Electro-deposition of tantalum on tungsten and nickel in LiF-NaF-CaF melt containing KTaF; Electrochemical study

Mehmood, M.*; Kawaguchi, Nobuaki*; Maekawa, Hideki*; Sato, Yuzuru*; Yamamura, Tsutomu*; Kawai, Masayoshi*; Kikuchi, Kenji

Materials Transactions, 44(2), p.259 - 267, 2003/02

https://doi.org/10.2320/matertrans.44.259

Electrochemical study has been carried out on the electro-deposition of tantalum in LiF-NaF-CaF melt containing KTaF at 700C. This has been done for determining the mechanistic features for preparing electrolytic coating of tantalum on nickel and tungsten substrates. Electro-deposition of metallic tantalum occurs primarily by electro-reduction of Ta(V). Pure metallic tantalum without any entrapped salt is successfully deposited on tungsten by galvanostatic polarization at reasonably low current densities. An additional feature on nickel is the formation of an intermetallic compound at potential 0.25V nobler than that of pure tantalum as a result of underpotential deposition of tantalum. This intermetallic compound covers the surface within a short time followed by deposition of pure tantalum, although intermetallic compound keeps growing at the interface of pure tantalum deposit and the substrate as a result of diffusion.

Acceleration irradiation test of first-loading fuel of High Temperature Engineering Test Reactor (HTTR) up to high burnup (Joint research)

Sawa, Kazuhiro; Sumita, Junya; Ueta, Shohei; Takahashi, Masashi; Tobita, Tsutomu*; Hayashi, Kimio; Saito, Takashi; Suzuki, Shuichi*; Yoshimuta, Shigeharu*; Kato, Shigeru*

JAERI-Research 2002-012, 39 Pages, 2002/06

JAERI-Research-2002-012.pdf:3.12MB

no abstracts in English

Modeling of fuel performance and fission product release behaviour during HTTR normal operation; A Comparative study on the FZJ and JAERI Modeling approach

Verfondern, K.*; Sumita, Junya; Ueta, Shohei; Sawa, Kazuhiro

JAERI-Research 2000-067, 127 Pages, 2001/03

JAERI-Research-2000-067.pdf:6.64MB

no abstracts in English

A Compact and high repetitive photodiode array detector for the JT-60U Thomson scattering diagnostic

Yoshida, Hidetoshi; Naito, Osamu; *; Kitamura, Shigeru; Hatae, Takaki; Nagashima, Akira

Review of Scientific Instruments, 70(1), p.747 - 750, 1999/01

https://doi.org/10.1063/1.1149435

no abstracts in English