The close marks the third steepest percentage fall in the Nikkei 's history . U.S. markets were set for a lower open . At one point , the Nikkei plunged more than 1,390 points , or more than 14 percent . Kan : Risk of further releases of radioactive material from Fukushima plant `` very high '' Nuclear safety agency says radiation levels at Japan's crippled nuclear power plants are still too high, but it is not clear if they will rise again soon enough to cause a serious accident.
The close marks the third steepest percentage fall in the Nikkei 's history . At one point , the Nikkei plunged more than 1,390 points , or more than 14 percent . Kan : Risk of further releases of radioactive material from Fukushima plant `` very high '' Nuclear safety agency says radiation levels at Japan's crippled nuclear power plants are still too high, but it is not clear if they will rise again soon enough to cause a serious accident.