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Journal Articles

Development of safety design technologies for sodium-cooled fast reactor coupled to thermal energy storage system with sodium-molten salt heat exchanger; Project overview

Yamano, Hidemasa; Kurisaka, Kenichi; Takano, Kazuya; Kikuchi, Shin; Kondo, Toshiki; Umeda, Ryota; Shirakura, Shota*

Dai-27-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu (Internet), 5 Pages, 2023/09

This project studies investigation on safety design guideline and risk assessment technology for sodium-cooled fast reactor with the molten-salt heat storage system, development of evaluation method for heat transferring performance between sodium and molten-salt and improvement of the performance, and evaluation of chemical reaction characteristic between sodium and molten-salt and improvement of its safety. The project overview is presented in this report.

Journal Articles

Development of safety design technologies for sodium-cooled fast reactor coupled to thermal energy storage system with sodium-molten salt heat exchanger

Yamano, Hidemasa; Kurisaka, Kenichi; Takano, Kazuya; Kikuchi, Shin; Kondo, Toshiki; Umeda, Ryota; Shirakura, Shota*; Hayashi, Masaaki*

Proceedings of 8th International Conference on New Energy and Future Energy Systems (NEFES 2023) (Internet), p.27 - 34, 2023/00

This project studies investigation on safety design guideline and risk assessment technology for sodium-cooled fast reactor with the molten-salt heat storage system, development of evaluation method for heat transferring performance between sodium and molten-salt and improvement of the performance, and evaluation of chemical reaction characteristic between sodium and molten-salt and improvement of its safety. The project overview is presented in this report.

Journal Articles

Experimental study on aerosol transport behavior in multiple cells with expandable connecting pipe for safety assessment of sodium-cooled fast reactors

Umeda, Ryota; Kondo, Toshiki; Kikuchi, Shin; Kurihara, Akikazu

Proceedings of 28th International Conference on Nuclear Engineering (ICONE 28) (Internet), 9 Pages, 2021/08

In this study, in order to obtain the fundamental information on aerosol transport behavior between cells, the Multiple cells with Expandable connecting pipe Test facility (MET) was manufactured and preliminary experiments were performed. In the preliminary experiments, simulated particles were used in a test system with two cells connected horizontally or vertically, and their transport behavior was measured. As a result, it was possible to confirm the behavior of the simulated particles transporting to the horizontal or vertical cells from the results such as images and sedimentation data.

Journal Articles

Experiments of self-wastage phenomena elucidation in steam generator tube of sodium-cooled fast reactor

Umeda, Ryota; Shimoyama, Kazuhito; Kurihara, Akikazu

Nihon Genshiryoku Gakkai Wabun Rombunshi, 19(4), p.234 - 244, 2020/12

Sodium-water reaction caused by failure of the steam generator tube of sodium-cooled fast reactor induce the wastage phenomenon, which has erosive and corrosive feature. In this report, the authors have performed the self-wastage experiments under high sodium temperature condition to evaluate the effect of wastage form/geometry by using two types of initial defect such as the micro fine pinhole and fatigue crack, and water leak rate on self-wastage rate. Based on the consideration of crack type influence, it was confirmed that self-wastage rate did not strongly depend on the initial defect geometry. As a mechanism of the self-plug phenomenon, it is speculated that sodium oxide intervenes and inhibits the progress of self-wastage. The dependence of initial sodium temperature on self-wastage rate was clearly observed, and new self-wastage correlation was derived considering the initial sodium temperature.

Journal Articles

Evaluation of target-wastage in consideration of sodium-water reaction environment formed on the periphery of an adjacent tube in steam generator of sodium-cooled fast reactor

Kurihara, Akikazu; Umeda, Ryota; Shimoyama, Kazuhito; Kikuchi, Shin

Nihon Kikai Gakkai Rombunshu (Internet), 84(859), p.17-00382_1 - 17-00382_11, 2018/03

Wastage on adjacent tubes (target-wastage) arise from water/steam leak in steam generators of sodium-cooled fast reactors (sodium-water reaction). Target-wastage is likely to be caused by liquid droplet impingement erosion (LDI) and Na-Fe composite oxidation type corrosion with flow (COCF) in an environment marked by high temperature and high-alkali (reaction jet) due to sodium-water reaction. In the previous study, the authors quantitatively evaluated the effect of material temperature and fluid velocity on COCF rate, and revealed that COCF was sodium-iron composite oxidation type corrosion from metallographic observation and element assay. In this study, the applicability of new wastage correlations was confirmed for each tube in sodium-water reaction test with straight vertical tube bundle under practical steam generator operation condition. The authors established that the new wastage correlations were applicable to each tube of tube bundle in the above test, and the time progress of wastage was qualitatively investigated for the two penetrated tubes in the period including the water and/or steam blowdown.

JAEA Reports

Phenomenon elucidation experiment for target wastage caused in steam generator of sodium-cooled fast reactor; Corrosion experiment in flowing high-temperature sodium hydroxide environment

Umeda, Ryota; Shimoyama, Kazuhito; Kurihara, Akikazu

JAEA-Technology 2017-018, 70 Pages, 2017/08

JAEA-Technology-2017-018.pdf:9.67MB

In case of the water leak into sodium in a SG of SFRs due to tube failure, reaction jet is formed by sodium-water reaction with exothermic heat. The reaction jet forms highly alkaline environment with high temperature and high pressure, which cause local thinning of adjacent heat transfer tubes (target wastage). In this report, for the purpose of elucidation of target wastage, the authors developed the experimental apparatus and experimental technique which enable the separate evaluation of wastage influence factors, including temperature, impingement velocity, reagent ratio and so on by using high temperature sodium hydroxide as major reaction product and sodium monoxide as secondary reaction product. In addition, the impingement corrosion experiments have been conducted by using high temperature reagents (NaOH and Na$$_{2}$$O). Based on the corrosive data, authors quantitatively evaluated the influence factors of wastage and formulated the average corrosive equations.

JAEA Reports

Rapid heating rupture experiment using the high chromium steel tubes

Umeda, Ryota; Kurihara, Akikazu; Shimoyama, Kazuhito

JAEA-Technology 2016-030, 50 Pages, 2016/12

JAEA-Technology-2016-030.pdf:5.22MB

In case of tube failure of a steam generator in sodium-cooled fast reactors, the reaction jet with high temperature and high velocity under highly alkaline environment is formed by cited exothermic reaction (sodium-water reaction). When the high temperature reaction jet covers the adjacent tubes, the material strength of tube decreases in the high temperature condition, and the adjacent tube may be swollen and failed by inner pressure (overheating tube rupture). For evaluation of the overheating tube rupture, tube failure is judged by comparison the hoop stress loaded by inner pressure with stress strength standard defined as creep strength depending on tube temperature. Thus, it is important to confirm the validation of this failure criterion based on the findings obtained in the simulated experiment of overheating tube rupture. In this report, for consideration on the validation of the failure criteria and elucidation on the failure mode and strength characteristics of failure, the authors carried out the rapid heating rupture experiment for the thin single and double-walled 9Cr steel tubes at high temperature up to 1500 K by using TRUST-2 rig in the Japan Atomic Energy Agency.

Journal Articles

Study on target wastage for sodium-water reaction environment formed on periphery of adjacent tube in steam generator of sodium-cooled fast reactor; Composite oxidation-type corrosion with flow experiment using high-temperature sodium hydroxide

Kurihara, Akikazu; Umeda, Ryota; Kikuchi, Shin; Shimoyama, Kazuhito; Ohshima, Hiroyuki

Nihon Genshiryoku Gakkai Wabun Rombunshi, 14(4), p.235 - 248, 2015/11

Sodium-water reaction would take place due to a breach of heat transfer tube in steam generator (SG) of sodium-cooled fast reactor (SFR), and the reaction jet may cause wear to the neighboring tubes by thermal and chemical effects, which is so-called target-wastage. Accordingly, failure propagation caused by target-wastage may potentially detract the secondary cooling system integrity. In previous study, a great number of target-wastage experiments have been carried out for candidate materials under practical SG operation conditions. Target-wastage rate was derived from macroscopic boundary factors of reaction jet. However, this mock-up approach is not versatile, and does not befit for large-scale SG design. Therefore, target-wastage should be focused for safety assessment of the various SG design. In this study, experiment apparatus and technique on composite oxidation type corrosion with flow (COCF), which is integral part of target-wastage, were constructed to figure out the separation effect of local wastage factors under the high temperature sodium hydroxide (NaOH) and sodium monoxide (Na$$_{2}$$O) environment mainly generated by SWR. The authors quantitatively evaluated the effect of material temperature and fluid velocity on COCF rate, and diffusion coefficient of Mod.9Cr-1Mo steel into NaOH-Na$$_{2}$$O. Besides, it was revealed that COCF was sodium-iron composite oxidation type corrosion from metallographic observation and element assay.

Journal Articles

Heat transfer characteristics of sodium-water reaction jet around a tube in steam generator of sodium-cooled fast reactor

Kurihara, Akikazu; Umeda, Ryota; Shimoyama, Kazuhito; Abe, Yuta; Kikuchi, Shin; Ohshima, Hiroyuki

Nihon Kikai Gakkai Rombunshu, B, 79(808), p.2640 - 2644, 2013/12

Overheating tube rupture of adjacent tubes arises from water/steam leak in steam generators of sodium-cooled fast reactors. It is very important to predict the tube wall stress (tube wall temperature) with a high degree of accuracy on evaluation of overheating tube rupture, and is crucial to estimate quantitatively the heat transfer coefficient between reaction jet and adjacent tubes which is one of the major influencing factor. The authors carried out the sodium-water reaction test (SWAT-1R) under the simulated operation condition of a real plant, and measured the correlation between heat transfer coefficient and void fraction around an adjacent tube. The authors confirmed that thermal environment around an adjacent tube was inferable from measured data, and heat transfer correlation equation proposed by Hamada et al. was applicable to the operation condition at elevated pressure and temperature.

Journal Articles

Cooperation on impingement wastage experiment of Mod. 9Cr-1Mo steel using SWAT-1R sodium-water reaction test facility

Beauchamp, F.*; Nishimura, Masahiro; Umeda, Ryota; Allou, A.*

Proceedings of International Conference on Fast Reactors and Related Fuel Cycles; Safe Technologies and Sustainable Scenarios (FR-13) (USB Flash Drive), 10 Pages, 2013/03

T91 is one of the material candidates of SGU tubes for future sodium-cooled fast reactors (SFRs). Wastage characterization of T91 is needed to evaluate the consequences for safety and the availability of the SGU. Six T91 target tubes were incorporated in the SWR test facility (SWAT-1R) of JAEA and subjected to reaction jets. All tubes were successfully penetrated by the reaction jets, and the wastage rates were determined. This paper describes the SWAT-1R facility, the test procedure and operating conditions, and brings out the main results and experience gained through the wastage experiments.

Journal Articles

Heat transfer characteristics inside an adjacent tube thermally-affected by sodium-water reaction in steam generator of sodium-cooled commercial fast reactor

Kurihara, Akikazu; Umeda, Ryota; Yanagisawa, Hideki*; Ohshima, Hiroyuki

Dai-16-Kai Doryoku, Enerugi Gijutsu Shimpojiumu Koen Rombunshu, p.9 - 10, 2011/06

In the case of sodium-water reaction accident in a steam generator of sodium-cooled fast reactors (FRs), adjacent heat transfer tubes may be damaged due to high temperature environment of the reaction field. For the purpose of understanding the overheating tube rupture mechanism, an experimental study has been performed to clarify waterside heat transfer characteristics during up-flow in a vertical tube under the real plant part-load operation conditions in which safety margin is least. A test tube was heated rapidly and the time averaged heat flux was estimated using an inverse solution. It was conformed that the heat transfer on the wall changed from nucleate boiling to transient-film boiling all over the heating section and dried-out surface spread from downstream toward upstream. We improved the heat transfer correlations applied to RELAP5 code and made sure the adequacy of these correlations to evaluate tube overheating.

Journal Articles

High-temperature sodium hydroxide impinging experiment for investigating tube wastage phenomena caused by sodium-water reaction in FBR steam generator

Kurihara, Akikazu; Ohshima, Hiroyuki; Shimoyama, Kazuhito; Umeda, Ryota

Nihon Kikai Gakkai Rombunshu, B, 77(776), p.964 - 968, 2011/04

Sodium reacts chemically with water in case of unexpected heat transfer tube failure in a steam generator (SG) of sodium-cooled fast breeder reactors (FBRs) and exothermic reaction produces reaction field with high temperature and high corrosive action (sodium-water reaction). Adjacent tubes are damaged due to erosive and corrosive environment of the reaction field (wastage). Therefore, it is integral to evaluate such sodium-water reaction phenomena with high accuracy for the safety assessment of FBRs. For the purpose of understanding the wastage mechanism, an experiment was carried out in which sodium hydroxide (NaOH) as the main reaction product collided with the tube material under high temperature conditions simulating the reaction field. We confirmed that the erosion-corrosion rate of tube material has a tendency to increase as the temperature and velocity of NaOH are raised.

Oral presentation

Erosion behavior of steam generator tube material in FBR caused by impacting high-temperature sodium hydroxide

Kurihara, Akikazu; Shimoyama, Kazuhito; Umeda, Ryota; Ohshima, Hiroyuki

no journal, , 

no abstracts in English

Oral presentation

High-temperature sodium hydroxide impinging experiment for investigating tube wastage phenomena caused by sodium-water reaction in FBR steam generator

Kurihara, Akikazu; Ohshima, Hiroyuki; Shimoyama, Kazuhito; Umeda, Ryota

no journal, , 

Sodium reacts chemically with water in case of unexpected heat transfer tube failure in a steam generator (SG) of sodium-cooled fast breeder reactors (FBRs), exoergic reaction produces reaction field with high temperature and high corrosive action (sodium-water reaction). Adjacent tubes are damaged due to erosive and corrosive environment of the reaction field. Therefore, it is integral to evaluate such sodium-water reaction phenomena with high accuracy for the safety assessment of FBRs. For the purpose of understanding the wastage mechanism, an experiment was carried out in which sodium hydroxide (NaOH) collided with the tube material under high temperature conditions simulating the reaction field. We confirmed that the erosion-corrosion rate of tube material has a tendency to increase as the temperature and velocity of NaOH are raised.

Oral presentation

Study on sodium-water reaction phenomena in steam generator of sodium-cooled fast reactor, 6; Thinning evaluation due to high-temperature sodium-hydroxide impinging experiment

Kurihara, Akikazu; Umeda, Ryota; Kikuchi, Shin; Ohshima, Hiroyuki

no journal, , 

It is quite important to evaluate the sodium-water reaction phenomena with high accuracy for the safety assessment of FBR SG, we have been developing the analysis method based on mechanistic approach. The reaction field with high temperature and high corrosive action was formed in case of sodium-water reaction, adjacent tubes are damaged due to erosive and corrosive environment of the reaction field (wastage). For the purpose of understanding the wastage mechanism, an experiment was carried out in which the tube material was immersed into sodium hydroxide (NaOH) under high temperature conditions to simulate the reaction field. We confirmed that the temperature dependence of NaOH/tube material on average corrosion rate.

Oral presentation

Development of experiment method due to high-temperature sodium hydroxide impinging

Umeda, Ryota; Shimoyama, Kazuhito; Kurihara, Akikazu

no journal, , 

In case of the water leak into sodium in a steam generator (SG) of sodium-cooled fast breeder reactors (FBRs), exothermic reaction produces reaction fields in association with high temperature and high corrosive action (sodium-water reaction). Adjacent tubes are damaged due to erosive and corrosive environment of the reaction field. Therefore, it is integral to evaluate such sodium-water reaction phenomena with high accuracy for the safety assessment of FBRs. For the purpose of understanding the wastage mechanism, we developed the new experimental apparatus and established the test procedure in which sodium hydroxide (NaOH) collided with the tube material under high temperature conditions simulating the reaction field.

Oral presentation

Study on sodium-water reaction phenomena in steam generator of sodium-cooled fast reactor, 12; Evaluation of thinning due to high-temperature sodium-hydroxide impinging experiment, 2

Kurihara, Akikazu; Kikuchi, Shin; Umeda, Ryota; Ohshima, Hiroyuki

no journal, , 

In order to clarify the wastage mechanism on the neighboring heat transfer tube in steam generator of sodium-cooled fast reactor, the impinging experiment was carried out under high-temperature sodium-hydroxide/sodium mono-oxide environment. We report the dependence of sodium-hydroxide/sodium mono-oxide temperature and collision velocity upon the thinning rate of material.

Oral presentation

The Effect of flow-accelerated corrosion with high-temperature sodium hydroxide on tube target-wastage caused in steam generator of sodium-cooled fast reactor

Kurihara, Akikazu; Kikuchi, Shin; Umeda, Ryota; Ohshima, Hiroyuki

no journal, , 

The wastage on adjacent tubes (target-wastage) is caused by water/steam leak accident in steam generator of sodium-cooled fast reactor. Target-wastage should arise from liquid droplet erosion and flow-accelerated corrosion in an environment marked by high-temperature and high-alkali (reaction jet) due to sodium-water reaction. The static and flow-accelerated corrosion experiments have been carried out as a part of phenomena clarification experiments for target-wastage by using tube material under high-temperature sodium-hydroxide and sodium mono-oxide conditions which were mainly generated by sodium-water reaction. The authors evaluated the dependence of regent/tube material temperature and impact velocity upon flow-accelerated corrosion of tube in this report.

Oral presentation

Study on sodium-water reaction phenomena in steam generator of sodium-cooled fast reactor, 19; Evaluation of thinning due to high-temperature sodium-hydroxide impinging experiment, 3

Kurihara, Akikazu; Kikuchi, Shin; Umeda, Ryota; Ohshima, Hiroyuki

no journal, , 

For the purpose of mechanism elucidation on target-wastage phenomena caused in steam generator of sodium-cooled fast reactor, impinging test was carried out under high temperature sodium-hydroxide/sodium monoxide environment. We quantitatively evaluated the effect of temperature and velocity on flow-accelerated corrosion rate, and derived new wastage correlation coupled with liquid droplet impingement erosion rate.

Oral presentation

Study on sodium-water reaction phenomena in steam generator of sodium-cooled fast reactor, 24; Development of experiment method for self-wastage behavior due to sodium-water reaction

Abe, Yuta; Shimoyama, Kazuhito; Umeda, Ryota; Kikuchi, Shin; Kurihara, Akikazu; Ohshima, Hiroyuki

no journal, , 

Self-wastage may take place due to corrosion related to chemical reaction between sodium and water in case of water/water vapor leak from the penetration crack on a tube of steam generator (SG) in sodium-cooled fast reactor (SFR). SFR plant and SG would be damaged by self-wastage when the corrosive thinning progressed up to inner wall of tube. Therefore, multi-dimensional sodium-water reaction analysis code has been developing for safety evaluation of SFR SG. The authors have constructed the experimental method to clarify self-wastage behavior using self-wastage experiment rig (SWAT-2R) and test specimen with fine leak hole.

48 (Records 1-20 displayed on this page)