To consider the disposal of the radioactive waste, the method of the geological disposal is a one of the ideas and we study about the long-term safety through the several simulations. Before the emplacement the disposal waste at underground, they will be stored for 30 or 50 year at one facility such as around nuclear power plant to cool their own heat down around 100 degree. And then, they will be contained into the steel canister and emplaced with the artificial material such as bentonite and concrete.

 As for the corrosion estimation, we’ve studied this speed and this phenomenon under several situations by using the electro-chemical impedance spectroscopy (EIS) measurement for the long-term safety and stability of this material. This paper describes the corroded phenomenon of the carbon steel around bentonite into the temperature storage and we elucidate this corroded condition by using EIS measurement. This EIS for the corrosion has been adopted for the one of the methods to estimate the corrosion condition from impedance frequency characteristic.

 As for our experiment, samples of the bentonite and carbon steel were compacted Kunigel V1 of 1.37Mg/m3 dry density with several  water contents and SM400 of  a low carbon steel to be set at inside of compacted bentonite. As for a heating regulation of the carbon steel, an electric heater was set inside at steel and kept 100 degree continuously. This model was made to a scale of 1/17 as a current concept of an vertical method of the disposal plan and reproduced an enclosed situation after the emplacement at underground of the radioactive waste. During the heating, we conducted an EIS measurement and set this data result as one equivalent circuit.

 In consequence, there were some difference trends of impedance frequency characteristic depending on the difference of the water content in bentonite and heating passage time. From this result, we estimated the corrosion condition and conductd to analyze the corrosion products after this experiment


Heating Impact on Corrosion Mechanism of Carbon Steel Surrounded by Bentonite

Division / Sponsors: 
Power Division & Nuclear Engineering Division (NED)

Power Conference
Paper Proceedings: https://asmedigitalcollection.asme.org/POWER/POWER2020/volume/83747

International Conference on Nuclear Engineering
Paper Proceedings: https://asmedigitalcollection.asme.org/ICONE/ICONE2020/volume/83761

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