Chernobyl (RBMK reactor) was basically a poor copy of a 1st-generation Hanford plutonium production reactor modified to produce some electricity. Oh, and the control rods had the cute property of SPEEDING UP the fission reaction when first inserted.

Those reactors are basically irrelevant in a safety discussion of modern reactor tech. Fukushima is more relevant — but again, it was a mid-60s design.