Bigge (2898) 

What is it? Nuclear reactor part?

Yes. The answer is in the album description: "A new cap for a nuclear reactor at the Palo Verde Nuclear Power Plant in Arizona. This cap was made in Korea and weighs 150 tons. The vehicle can move only 5 MPH, only at night, and only for ten hours at a stretch. Today this load is sitting south of Desert Hot Springs on Dillon Road. Tonight it will go up route 62 into the high desert."

Fasinating Ron, Good capture. One of those unusual mechanical objects that one will only see once. Installation of this should be equally interesting. I bet the crane to lift that baby will be equally as intersting. Thanks for the Pics!