On July 10, 2013, the Unit 2 reactor at Diablo Canyon in California shut itself down following a a voltage irregularity from the unit’s diesel generator. According to the report sent to the NRC:
The preliminary cause of the differential relay actuation was a flashover of Phase A 500 kV to ground across the Phase A lightning arrestor during maintenance activities to wash the 500 kV insulators.
This raises a couple of question: Is it standard operating procedure to spray water on operating electrical equipment? And, aren’t insulators installed to prevent electrical surges?
The graphic requires some explanation. On an episode of The Simpsons, Mr. Burns is talking about The Plywoood Pelican, a wooden airplane he designed during World War II. The plane made one short test flight, but, as Mr. Burns explains, “…then we discovered that rain made it catch fire.”