Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors; Project overview and progress until JFY2022

Yamano, Hidemasa; Takai, Toshihide; Emura, Yuki; Fukuyama, Hiroyuki*; Nishi, Tsuyoshi*; Morita, Koji*; Nakamura, Kinya*; Pellegrini, M.*

Nihon Kikai Gakkai 2023-Nendo Nenji Taikai Koen Rombunshu (Internet), 5 Pages, 2023/09

A research project has been conducting thermophysical property measurement of a eutectic melt, eutectic melting reaction and relocation experiments, eutectic reaction mechanism investigation, and physical model development on the eutectic melting reaction for reactor application analysis in order to simulate the eutectic melting reaction and relocation behavior of boron carbide as a control rod material and stainless steel during a core disruptive accident in an advanced sodium-cooled fast reactor designed in Japan. This paper describes the project overview and progress until JFY2022.

Kinetic study on eutectic reaction between boron carbide and stainless steel by differential thermal analysis

Kikuchi, Shin; Nakamura, Kinya*; Yamano, Hidemasa

Mechanical Engineering Journal (Internet), 8(4), p.20-00542_1 - 20-00542_13, 2021/08

https://doi.org/10.1299/mej.20-00542

In a postulated severe accidental condition of sodium-cooled fast reactor (SFR), eutectic melting between boron carbide (BC) and stainless steel (SS) may take place. Thus, kinetic behavior of BC-SS eutectic melting is one of the important phenomena to be considered when evaluating the core disruptive accidents in SFR. In this study, for the first step to obtain the fundamental information on kinetic feature of BC-SS eutectic melting, the thermal analysis using the pellet type samples of BC and Type 316L SS as different experimental technique was performed. The differential thermal analysis endothermic peaks for the BC-SS eutectic melting appeared from 1483K to 1534K and systematically shifted to higher temperatures when increasing heating rate. Based on this kinetic feature, apparent activation energy and pre-exponential factor for the BC-SS eutectic melting were determined by Kissinger method. It was found that the kinetic parameters obtained by thermal analysis were comparable to the literature values.

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 1; Project overview and progress until 2018

Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro; Kikuchi, Shin; Emura, Yuki; Kamiyama, Kenji; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; et al.

Proceedings of 2020 International Conference on Nuclear Engineering (ICONE 2020) (Internet), 10 Pages, 2020/08

https://doi.org/10.1115/ICONE2020-16102

One of the key issues in a core disruptive accident (CDA) evaluation in sodium-cooled fast reactors is eutectic reactions between boron carbide (BC) and stainless steel (SS) as well as its relocation. Such behaviors have never been simulated in CDA numerical analyses in the past, therefore it is necessary to develop a physical model and incorporate the model into the CDA analysis code. This study focuses on BC-SS eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in a range from solid to liquid state. The physical model is developed for a severe accident computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress of experimental and analytical studies conducted until 2018. Specific results in this paper are boron concentration distributions of solidified BC-SS eutectic sample in the eutectic melting experiments, which would be used for the validation of the eutectic physical model implemented into the computer code.

Study on eutectic melting behavior of control rod materials in core disruptive accidents of sodium-cooled fast reactors, 1; Project overview

Yamano, Hidemasa; Takai, Toshihide; Furukawa, Tomohiro; Kikuchi, Shin; Emura, Yuki; Kamiyama, Kenji; Fukuyama, Hiroyuki*; Higashi, Hideo*; Nishi, Tsuyoshi*; Ota, Hiromichi*; et al.

Proceedings of International Nuclear Fuel Cycle Conference / Light Water Reactor Fuel Performance Conference (Global/Top Fuel 2019) (USB Flash Drive), p.418 - 427, 2019/09

Eutectic reactions between boron carbide (BC) and stainless steel (SS) as well as its relocation are one of the key issues in a core disruptive accident (CDA) evaluation in sodium-cooled fast reactors. Since such behaviors have never been simulated in CDA numerical analyses, it is necessary to develop a physical model and incorporate the model into the CDA analysis code. This study is focusing on BC-SS eutectic melting experiments, thermophysical property measurement of the eutectic melt, and physical model development for the eutectic melting reaction. The eutectic experiments involve the visualization experiments, eutectic reaction rate experiments and material analyses. The thermophysical properties are measured in the range from solid to liquid state. The physical model is developed for a severe accident computer code based on the measured data of the eutectic reaction rate and the physical properties. This paper describes the project overview and progress of experimental and analytical studies by 2017. Specific results in this paper is boron concentration distributions of solidified BC-SS eutectic sample in the eutectic melting experiments, which would be used for the validation of the eutectic physical model implemented into the computer code.

Fuel and core design studies on metal fuel sodium-cooled fast reactor (4), (5) and (6); Joint research report for JFY2009 - 2012

Uematsu, Mari Mariannu; Sugino, Kazuteru; Kawashima, Katsuyuki; Okano, Yasushi; Yamaji, Akifumi; Naganuma, Masayuki; Oki, Shigeo; Okubo, Tsutomu; Ota, Hirokazu*; Ogata, Takanari*; et al.

JAEA-Research 2012-041, 126 Pages, 2013/02

JAEA-Research-2012-041.pdf:16.49MB

The characteristics of sodium-cooled metal fuel core compared to MOX fuel core are given by its higher heavy metal density and superior neutron economy. By taking advantage of these characteristics and allowing flexibility in metal fuel specification and core design conditions as sodium void reactivity and bundle pressure drop, core design with high burnup, high breeding ratio and low fuel inventory features will be achievable. On ground of the major achievements in metal fuels utilization as driver fuels in sodium fast reactors in U.S., the metal fuel core concept is selected as a possible alternative of MOX fuel core concept in FaCT project. This report describes the following items as a result of the joint study on "Reactor core and fuel design of metal fuel core of sodium-cooled fast reactor" conducted by JAEA and CRIEPI during 4 years from fiscal year 2009 to 2012.

Establishment of technological basis for fabrication of U-Pu-Zr ternary alloy fuel pins for irradiation tests in Japan

Kikuchi, Hironobu; Nakamura, Kinya*; Iwai, Takashi; Nakajima, Kunihisa; Arai, Yasuo; Ogata, Takanari*

Nihon Genshiryoku Gakkai Wabun Rombunshi, 10(4), p.323 - 331, 2011/12

https://doi.org/10.3327/taesj.J11.006

A high-purity Ar gas atmosphere glovebox accommodating injection casting and sodium-bonding apparatuses was newly installed in Plutonium Fuel Research Facility (PFRF) of Oarai Research and Development Center, Japan Atomic Energy Agency. Past experiences in PFRF led to the establishment of technological basis of fabrication of U-Pu-Zr alloy fuel pin for the first time in Japan. After the injection casting of U-Pu-Zr alloy, the metallic fuel pins are fabricated by welding upper- and lower end plugs with cladding tube of ferritic-martensitic steel. Subsequent to the sodium bonding for filling the annular gap region between the U-Pu-Zr alloy and cladding tube with the melted sodium, the fuel pins are subjected to the inspection for irradiation tests. This paper summarizes the equipment of the apparatuses and the technological basis for fabrication of U-Pu-Zr alloy fuel pins for the coming irradiation test in the experimental fast test reactor JOYO.

Fabrication of U-Pu-Zr metallic fuel elements for irradiation test at Joyo

Nakamura, Kinya*; Ogata, Takanari*; Kikuchi, Hironobu; Iwai, Takashi; Nakajima, Kunihisa; Kato, Tetsuya*; Arai, Yasuo; Koyama, Tadafumi*; Itagaki, Wataru; Soga, Tomonori; et al.

Proceedings of International Conference on Toward and Over the Fukushima Daiichi Accident (GLOBAL 2011) (CD-ROM), 8 Pages, 2011/12

CRIEPI and JAEA have fabricated sodium-bonded metallic fuel elements for the first time in Japan as a collaborative research, for use in the irradiation test at the experimental fast test reactor Joyo. The irradiation test aims to assess the irradiation behavior of the fuel and the internal wastage of the stainless-steel cladding by rare-earth fission products at a maximum cladding temperature above 873 K. U-20 wt% Pu-10 wt% Zr alloy fuel slugs of 200 mm length were fabricated in an injection-casting furnace using U metal, U-Pu alloy and Zr metal. Two types of fuel slug were fabricated, i.e., 5.05 mm and 4.95 mm in diameter, and loaded into a ferritic-martensitic stainless-steel cladding tubes, respectively. After top-end-plug welding to the cladding tube, each fuel element was subjected to sodium bonding to fill the annular gap between the fuel slug and the cladding with melted sodium. The fabrication results indicated that the characteristics of the fuel elements were within the required specifications.

Welding of metallic fuel elements for the irradiation test in JOYO; Preliminary tests and welding execution tests (Joint research)

Kikuchi, Hironobu; Nakamura, Kinya*; Iwai, Takashi; Arai, Yasuo

JAEA-Technology 2009-049, 22 Pages, 2009/10

JAEA-Technology-2009-049.pdf:13.99MB

Irradiation tests of metallic fuels elements in fast test reactor JOYO are planned under the joint research of Japan Atomic Energy Agency (JAEA) and Central Research Institute of Electric Power Industry (CRIEPI). Six U-Pu-Zr fuel elements clad with ferritic martensitic steel are fabricated in Plutonium Fuel Research Facility (PFRF) of JAEA-Oarai for the first time in Japan. In PFRF, the procedures of fabrication of the fuel elements were determined and the test runs of the equipments were carried out before the welding execution tests for the fuel elements. Test samples for confirming the welding condition between the cladding tube and top and bottom endplugs were prepared, and various test runs were carried out before the welding execution tests. As a result, the welding conditions were finalized by passing the welding execution tests.

Development of metal fuel fabrication technology for irradiation test in JOYO; Production of uranium-plutonium alloy by electrochemical reduction

Kato, Tetsuya*; Nakamura, Kinya*; Nakajima, Kunihisa; Iwai, Takashi; Arai, Yasuo

Denryoku Chuo Kenkyusho Hokoku (L05010), 13 Pages, 2006/07

no abstracts in English

Pyrometallurgical production of U-Pu alloy and injection casting of U-Pu-Zr

Nakamura, Kinya*; Yokoo, Takeshi*; Arai, Yasuo

Transactions of the American Nuclear Society, 94(1), P. 780, 2006/06

no abstracts in English