To the right is an image of a radioactive waste storage site at Orchid Island, Taiwan. As you can see, there is a lot of dirt and corrosion, and its all encased in crubling concrete. This photo served as inspiration for my looks like Nuclear Core sketch model!
The sketch model itself is meant to look like old, slightly decrepit and decaying concrete with housing for the nuclear control rods. It is made out of shaped blue foam with sanded finish. I then took some spraypaint (knowing it is corrosive to blue foam) and sprayed it on the bare foam model in irregular ways. The desired corrosion effect was achieved, so then I painted over the outside with a grey paint, accenting with darker greys and whites in some areas. Lastly, I put tape in the control rod slots to make the bottoms smoother, and painted those black.
This is how the look's like concept fits into the storyboard--the Nuclear Core sits right in the middle of the control rod chamber.