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Journal Articles

Development of the residual sodium quantification method for a fuel pin bundle of SFRs before and after dry cleaning

Kudo, Hideyuki*; Otani, Yuichi*; Hara, Masahide*; Kato, Atsushi; Otaka, Masahiko; Ide, Akihiro*

Journal of Nuclear Science and Technology, 57(4), p.408 - 420, 2020/04

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

In a fuel handling system of sodium-cooled fast reactors (SFRs), it is necessary to remove the sodium remaining on spent fuel assemblies (FAs) before storing them in a spent fuel water pool (SFP) in order to minimize plant operating loads. A next-generation SFR in Japan has adopted an advanced dry cleaning process which consists of the following steps, argon gas blowing to remove the metallic residual sodium on the FA, moist argon gas blowing to deactivate the residual sodium, and direct storage in the SFP. This three-step process increases economic competitiveness and reduces waste products thanks to a waterless process. In this R&D work, performance of the dry cleaning process has been investigated.

Journal Articles

Development of the residual sodium quantification method for a fuel assembly of SFRs

Kudo, Hideyuki*; Inuzuka, Taisuke*; Hara, Masahide*; Kato, Atsushi; Nagai, Keiichi; Ide, Akihiro*

Journal of Nuclear Science and Technology, 57(1), p.9 - 23, 2020/01

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

In sodium-cooled fast reactors (SFRs), it is necessary to remove the sodium remaining on spent fuel assemblies (FAs) before storing them in a spent fuel water pool (SFP) in order to minimize plant operating loads. A next-generation SFR in Japan has adopted an advanced dry cleaning process which consists of the following steps: argon gas blowing to remove the metallic residual sodium on the FA, moist argon gas blowing to deactivate the residual sodium, and direct storage in the SFP. This process increases economic competitiveness and reduces waste products. In this RD work, performance of the dry cleaning process has been investigated. This paper describes experimental and analytical work focusing on the amount of residual sodium remaining on FA components, for instance the handling head, the wrapper tube, the upper shielding, and the entrance nozzle which was conducted after investigation of residual sodium on fuel pin bundles as a part of series study of the cleaning process.

Journal Articles

Dry cleaning process test for fuel assembly of fast reactor plant system, 1; Pilot scale test for fuel pin bundle

Kudo, Hideyuki*; Otani, Yuichi*; Hara, Masahide*; Kato, Atsushi; Ishikawa, Nobuyuki; Otaka, Masahiko; Nagai, Keiichi; Saito, Junichi; Ara, Kuniaki; Ide, Akihiro*

Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 10 Pages, 2019/05

A next generation SFR in Japan has adopted an advanced dry cleaning system which consists of the argon gas blowing process to reduce the amount of metallic residual sodium remaining on spent fuel assemblies. This paper describes experimental and analytical work focusing on the amount of residual sodium remaining on a fuel pin bundle before and after the argon gas blowing process. The experiments were conducted using a sodium test loop and a short specimen consisting of a 7 pin bundle. The effects of the blowing gas velocity and the blowing time were quantitatively analyzed in the experiments. On the basis of these experimental results, evaluation models predicting the amount of the residual sodium were constructed.

Journal Articles

Dry cleaning process test for fuel assembly of fast reactor plant system, 2; Laboratory scale test for fuel assembly and evaluation of the amount of residual sodium

Ide, Akihiro*; Kudo, Hideyuki*; Inuzuka, Taisuke*; Hara, Masahide*; Kato, Atsushi; Ishikawa, Nobuyuki; Otaka, Masahiko; Nagai, Keiichi; Saito, Junichi; Ara, Kuniaki

Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 10 Pages, 2019/05

A next generation SFR in Japan has adopted an advanced dry cleaning system which consists of the following process of argon gas blowing to reduce the amount of metallic sodium, moist argon gas blowing to deactivate the residual sodium, and direct storage in the SFP without using storage containers. This three-step process increases economic competitiveness and reduces waste products. In this Research and Development work, the amount of residual sodium and performance of the dry cleaning process were investigated. This paper describes experimental and analytical work for all parts of a fuel assembly except for a fuel pin bundle.

Journal Articles

Development of erosion test methods on underexpanded inert-gas impinging jets injected in liquid sodium

Kudo, Hideyuki*; Ota, Junki*; Sugiyama, Kenichiro*; Narabayashi, Tadashi*; Ohshima, Hiroyuki; Kurihara, Akikazu

Hozengaku, 11(4), p.90 - 97, 2013/01

When a heat transfer tube wall in a steam generator of a sodium-cooled fast reactor fails, high-pressure steam leaks into low-pressure liquid sodium side. Then the high-temperature and highly corrosive reaction jet causes secondary failures of neighboring heat transfer tubes. The objective of the present study is to develop an experimental method to obtain data that is necessary to validate and improve a safety evaluation code on the sodium-water reaction. In the present paper, a method of sodium-droplet erosion test at the position of the local structure in underexpanded inert-gas impinging jets using the visualization method, which was developed in our previous study, was reported. The erosion phenomena observed in the sodium-droplet entrained region, where intensive erosion is expected, were found to be discussed using the existing knowledge of liquid droplet impingement (LDI) obtained in water experiments.

Journal Articles

Visualization on the behavior of inert gas jets impinging on a single glass tube submerged in liquid sodium

Kudo, Hideyuki*; Sugiyama, Kenichiro*; Narabayashi, Tadashi*; Ohshima, Hiroyuki; Kurihara, Akikazu

Journal of Nuclear Science and Technology, 50(1), p.72 - 79, 2013/01

 Times Cited Count:6 Percentile:49.64(Nuclear Science & Technology)

In order to accurately model sodium-water reaction jets in steam generators of fast breeder reactors, knowledge of size distributions or mean diameters of liquid sodium droplets entrained into the reaction jets are prerequisite. In the present study, argon-gas jet behaviors, without chemical reaction, injected into liquid sodium were successfully visualized using an endoscope and a glass tube, and the size distributions and mean diameters of liquid sodium droplets entrained into the gas jet were also obtained in the bubbling regime.

Journal Articles

Void fraction distributions of inert gas jets across a single cylinder with non-wetting surface in liquid sodium

Kudo, Hideyuki*; Zhao, D.*; Sugiyama, Kenichiro*; Narabayashi, Tadashi*; Ohshima, Hiroyuki; Kurihara, Akikazu

Journal of Nuclear Science and Technology, 49(12), p.1175 - 1185, 2012/12

 Times Cited Count:2 Percentile:20.56(Nuclear Science & Technology)

Little work on the void fraction behaviors along structural materials with poor-wettability for liquid metals has been performed. In the present study, void fraction behaviors around a single cylinder with non-wetting surface condition were quantitatively discussed by using a gas jet-cylinder system where the impinging jet flow, the boundary layer flow, the separation flow, and the wake flow appear. The characteristics in each flow field as well as the relationship between flow fields, which have not been quantitatively discussed so far, are obtained. The local void fraction around a single cylinder with wetting condition or non-wetting condition was measured by using resistivity probes.

Journal Articles

Visualization on inert gas jets impinging to a glass tube submerged in liquid sodium

Kudo, Hideyuki*; Sugiyama, Kenichiro*; Narabayashi, Tadashi*; Ohshima, Hiroyuki; Kurihara, Akikazu

Proceedings of 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference (ICONE-20 & POWER 2012) (DVD-ROM), 6 Pages, 2012/07

For the sodium-water reaction accident, it is important to grasp the structure of gas jets submerged in liquid sodium and associated droplet size. In this study, we successfully obtained visualized images of inert gas jets injected into liquid sodium. Formation processes of liquid sodium droplets entrained into the gas jets and drop-size distributions are discussed.

Oral presentation

None

Kawatsuma, Shinji; Funabashi, Hideyuki; Yagi, Naoto; Kudo, Kenji; Tsujimura, Seiichi; Fukushima, Tadashi

no journal, , 

no abstracts in English

Oral presentation

Thermal hydraulic behavior around a single heated rod with sodium-water reaction, 1

Kudo, Hideyuki*; Nishizaki, Masanori*; Sugiyama, Kenichiro*; Ohshima, Hiroyuki

no journal, , 

A fundamental experiment was performed to clarify thermal-hydraulic phenomena around a heat transfer tube of steam generator of sodium cooled fast reactor under sodium-water reaction condition. Argon gas jet with water vapor was impinged on a single heated rod surrounded by liquid sodium. Thermal hydraulic behavior on and around the rod was clarified through the measured data.

Oral presentation

Thermal hydraulic behavior around a single heated rod with sodium-water reaction, 2

Kudo, Hideyuki*; Nishizaki, Masanori*; Sugiyama, Kenichiro*; Ohshima, Hiroyuki; Kurihara, Akikazu

no journal, , 

no abstracts in English

Oral presentation

Effect of wettability on void fraction distribution around a cylinder in sodium

Kudo, Hideyuki*; Sugiyama, Kenichiro*; Narabayashi, Tadashi*; Ohshima, Hiroyuki; Kurihara, Akikazu

no journal, , 

no abstracts in English

Oral presentation

Effect of wettability on heat transfer distribution around a cylinder in sodium

Zhao, D.*; Kudo, Hideyuki*; Sugiyama, Kenichiro*; Ohshima, Hiroyuki; Kurihara, Akikazu

no journal, , 

no abstracts in English

Oral presentation

Visualization on inert gas jets impingement to a glass tube submerged in liquid sodium

Noguchi, Yuhei*; Kudo, Hideyuki*; Ota, Junki*; Sugiyama, Kenichiro*; Ohshima, Hiroyuki; Kurihara, Akikazu

no journal, , 

As the final goal to understand the sodium-water reaction phenomena of steam generator in sodium-cooled fast reactor, we observed directly the colliding behavior of inactive gas jet in sodium from inside a single glass cylinder. And we calculated the void fraction from the frame due to the high speed video camera, and compared with the value measured by void sensor.

Oral presentation

Visualization on inert gas jets impinging to a single cylinder submerged in liquid sodium

Kudo, Hideyuki*; Sugiyama, Kenichiro*; Ohshima, Hiroyuki; Kurihara, Akikazu

no journal, , 

It is important to understand the behavior of inactive gas jet and entrained liquid diameter in liquid sodium. Therefore we observed the shape of the inactive gas colliding with glass cylinder in liquid sodium from inside the glass cylinder.

Oral presentation

Factors affecting the leaching of nitrogen species from diatomaceous mudstone

Igarashi, Toshifumi*; Ueda, Takahiro*; Hokora, Hideyuki*; Jo, Mayumi*; Kudo, Hajime

no journal, , 

Horonobe Underground Research Center, located in northern Hokkaido, Japan, has been excavating shafts and drifts of an underground research facility to establish general techniques for the assessment of deep geological environment. In this site, the groundwater seepage from the shafts and drifts as well as leachate from the excavated rock storage site contain high concentrations of total nitrogen. Ammonium-nitrogen (NH$$_{4}$$-N), the major nitrogen species in the seepage and leachate, has been removed by a nearby treatment facility. However, NH$$_{4}$$-N is easily oxidized to nitrite-nitrogen (NO$$_{2}$$-N) and nitrate-nitrogen (NO$$_{3}$$-N) by nitrification in the excavated rock storage site, which makes the removal process employed on site less effective. Therefore, column experiments that simulated the infiltration of rainwater through the storage site were carried out to understand the leaching and nitrification of nitrogen species and the factors affecting the phenomena. The results showed that the nitrification was inhibited when the rock layer was almost saturated, and that this process was temperature dependent. These indicate that nitrification can be mitigated by controlling hydrological conditions like water saturation.

Oral presentation

Dry cleaning process test for fuel assembly of fast reactor plant system, 3; Sodium loop test

Kudo, Hideyuki*; Otani, Yuichi*; Hara, Masahide*; Otaka, Masahiko; Nagai, Keiichi; Saito, Junichi; Ishikawa, Nobuyuki; Ara, Kuniaki; Ide, Akihiro*

no journal, , 

no abstracts in English

Oral presentation

Dry cleaning process test for fuel assembly of fast reactor plant system, 4; Laboratory scale test and evaluation results of the amount of residual sodium on a fuel assembly

Ide, Akihiro*; Otaka, Masahiko; Nagai, Keiichi; Saito, Junichi; Ishikawa, Nobuyuki; Ara, Kuniaki; Kudo, Hideyuki*; Inuzuka, Taisuke*; Hara, Masahide*

no journal, , 

no abstracts in English

18 (Records 1-18 displayed on this page)
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