* Nikkei falls almost 2 percent * Europe-related stocks battered * Power companies surge as PM hints nuclear plants to restart By Sophie Knight TOKYO, May 31 (Reuters) - Japan's Nikkei share average fell sharply in early trade on Thursday, with exporters such as Canon Inc and Mazda buckling under a strong yen and risk aversion heightened after Spain and Italy appeared increasingly unable to finance their own debt. The Nikkei fell 1.9 percent to 8,471.66 , smashing through the psychologically important 8,500 level as the yen firmed to a four and a-half month high against the euro after Italian 10-year bond yields breached the 6 percent danger level on Wednesday. The broader Topix index fell 1.5 percent to 712.98. "A slight sense of panic emerged last night in the U.S.