PS: How old are graphite reactors? They go as far back as the Chicago Pile-1 in 1942. Nobody designs graphite reactors anymore because the hot graphite has a nasty habit of catching fire when exposed to oxygen, as in the case of Chernobyl.
I don't wish to demonize graphite as a moderator because it works quite nicely but another major safety issue with RMBK (or other graphite moderated) reactors is that the moderator and coolant are completely separate. If you lose the coolant the nuclear reaction continues. Not to ignore the myriad of other reactor designs out there, but light water reactors in contrast to RMBKs use water as the coolant and moderator. In a loss of coolant type scenario the nuclear reaction will essentially stop. This is not to say that you'd be completely out of the woods since you'd still have all the various sources of decay heat and whatnot (as was seen in Japan) that can still make one hell of a mess.
"If you want to eat hippopatomus, you've got to pay the freight." -- attributed to an IBM guy, about why IBM software uses so much memory