radiation effects on partial discharge

[electricpete]

For nuclear power plants, the safety-related motors which can be exposed to a radiation field have a special insulation system that is designed and qualified to withstand high levels of radiation as a result of regulatory requirements.

However there are often various non-safety motors that are procured with standard commercial insulation systems (no radiation qualification or testing) and exposed to relatively high radiation levels during operation. I am thinking mostly about 13.2kv reactor coolant pump motors which are located inside the bioshield.

Would you expect the radiation to cause any difference in partial discharge occurring inside the insulation or on the winding surfaces?
Would you expect the radiation to cause any difference in the ability to detect actual partial discharge using a partial-discharge sensing coupling capacitor?


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(2B)+(2B)' ?

 

[itsmoked]

I would expect a difference. There will be ionizing radiation. Gamma rays that are going to be knocking electrons off their atoms. It should alter any process or phenomena that has to do with ionization.

How much? I don't know.

I would expect partial discharge to be different. If the coupling capacitor is outside the radiation field it should perform normally. Inside the field it will likely read differently due to it's own response to radiation.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[hesselberth]

Actually the issue with Nuclear motors both Class 1E & NonClass 1E is the heat. Outside containment they have a 40 year design life (soon to be updated to 60 years) From test reports I've read from Baldor/Reliance, the dielectric strength increases when subjected to 2 X 10-8 rads. Inside containment they are designed to operate for 6 hours @ 301-deg F during accident. Low voltage motors are designed to operate for 100 days @ 301 F

 

[electricpete]

Thanks for the responses.

The heat you are talking about I believe would be something like a loss of coolant accident or high energy line break, and the concern would be continued operation of the machine after that even / accident.

This post is not concerned with continued operation after the accident. It is concerned with the effects of routine operation in a radiation environment. Also I'm guessing the Baldor/Reliance reports you refer to were random wound low voltage motors. This would be a form wouund medium voltage motor.

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(2B)+(2B)' ?