NHK's english language TV feed just reported the explosion 11:08AM JST 3/14/11 in Daiichi 3 reactor building as probably another hydrogen explosion, similar to the explosion at Daiichi 1 earlier. They'd been venting hydrogen similarly in both cases. If so no more effect on the big radiation risk picture than what had happened before. However there certainly could be casualties from the explosion and it may move back their repair and control efforts. They're playing a live press conference now. Sea water pumping into Daiichi 3 still continues, the reactor vessel remains intact and they don't anticipate much, if any, radiation release from this.