The plant comprised six separate boiling water reactors originally designed by General Electric (GE) and maintained by the Tokyo Electric Power Company (TEPCO). At the time of the earthquake, reactor 4 had been de-fueled and reactors 5 and 6 were in cold shutdown for planned maintenance.
Background radiation is 30 CPM. Near the ocean it's 150 CPM. The fine mist coming from the ocean waves seems to be what makes the Geiger Counter jump up 6X.