Why don't you keep reading the article on the list submarines that you referenced, all the way down to the 4th paragraph that talks about causes of sinking. 1

Why don't you keep reading the article on the list submarines that you referenced, all the way down to the 4th paragraph that talks about causes of sinking. 1 of 9 (Soviet K-37) was scuttled with no loss of life due to reactor issues spanning years. 1 had an undetermined cause of sinking with theories having to do with the usual submarine issues (fire, torpedo accent, ballast/pressure issues), not its reactor. All others were lost for reasons having nothing to do with nuclear reactors.