San Onofre nuclear power plant

TOKYO, Japan - File photo taken in March 2011 shows the San Onofre nuclear power plant in southern California. The number of incidents of abnormal attrition -- or wearing away or grinding down by friction -- found in Japanese-made steam generator tubes in two reactors at the power plant has reached around 15,000, the U.S. Nuclear Regulatory Commission said in a report on July 12, 2012.