What you need are stronger reactor walls. (Simple answer) SWCH counts? (ACID can break it)
How about VIRR with a simple CFLM cooling system?
Insl and ttan layers are definitley the best destroyable reactor components. However, you can switch to aray or gravity shielding for fusion, the plasma really makes it hard to control, making those the best that you can use without making the reactor too indestructable.