Electrical Breakdown in Equipment in Argon Atmospere

12/10/2025 2025 - #04 Physics and technology of nuclear reactors

Smirnov V.P. Mytarev A.V. Kostiuchenko A.N. Leshchenko A.Yu. Nosov A.V.

https://doi.org/10.26583/npe.2025.4.02

To design and implement the equipment for spent fuel pyrochemical processing, experimental prototypes of the in-cell equipment for argon-filled hot cells were made. The experience has shown that the electric drives with industrial asynchronous motors failed frequently. The research studies in the argon glovebox revealed the electric drive failure were caused by both the electric breakdown in connector contacts in the motor power circuits and the direct arcing in the motor windings. The main reasons are poor heat transfer properties and lower breakdown voltage of argon compared with the air. The results indicate that the argon breakdown voltage can be 25% of the air breakdown voltage. To ensure performance of the electric connector in the argon, it is recommended to select a connector with increased contact spacing, to minimize the number of connectors, and to use contacts that are spaced far from each other, not the adjacent ones. These recommendations, being tested on the in-cell equipment, demonstrated their efficiency: none of the failures related to the connector performance in the argon atmosphere had no longer occurred.

Also, the research identified that the difference in temperature between the motor winding and the argon atmosphere can be 27% larger than that for the air. To maintain long continuous operation of the electric motors in the argon atmosphere, the next research should include testing of some measures. Proposals for stepping motors:

• Select a motor with a higher rated torque;
• Set the motor winding current to be less than the rated value considering the proportionally reduced torque;
• Limit the maximum rotation speed of the motor shaft;
• Take measures to improve the efficiency of heat transfer from the motor surface: enlarge the heat transfer area, add extra radiators, provide the forced circulation of argon atmosphere;
• Minimize power voltage;
• Provide temperature sensors and ensure the motor power supply interruption whenever its temperature is above the set value. Proposals for asynchronous motors:
• Select a motor with rated power reserve;
• Limit the minimum rotation speed of the motor shaft;
• Provide the forced circulation of argon atmosphere surrounding the motor;
• Monitor performance of extra cooling fans;
• Provide temperature sensors and ensure the motor power supply interruption whenever its temperature is above the set value.

The efficiency of proposals above should be studied with further tests.

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argon electrical breakdown electric connector electric motor hot cell spent fuel pyrochemical processing

Link for citing the article: Smirnov V.P., Mytarev A.V., Kostiuchenko A.N., Leshchenko A.Yu., Nosov A.V. Electrical Breakdown in Equipment in Argon Atmospere. Izvestiya vuzov. Yadernaya Energetika. 2025, no. 4, pp. 19-28; DOI: https://doi.org/10.26583/npe.2025.4.02 (in Russian).