The operator of Japan's stricken Fukushima nuclear power plant said on Monday that contaminated ground water had likely been flowing into the sea, acknowledging such a leakage for the first time.
Tokyo Electric Power Co., or Tepco, made the announcement a day after Prime Minister Shinzo Abe's pro-nuclear Liberal Democratic Party and its junior coalition partner scored a decisive victory in elections to the upper house, cementing his grip on power.
The head of Japan's new Nuclear Regulation Authority, created since the March 2011 earthquake and tsunami wrecked Fukushima, said this month he believed contamination of the sea had been continuing since the accident.
But Tepco had previously failed to confirm the ground water leakage more than two years after the worst nuclear accident since Chernobyl in 1986.
"We would like to offer our deep apology for causing grave worries for many people, especially for people in Fukushima," Masayuki Ono, Tepco's general manager, told a news conference in comments broadast on public NHK television.
Tepco said that based on water sample tests, any impact of the leakage appeared to be contained by silt fences erected near the devastated reactors.
The utility is already injecting the chemical sodium silicate into part of the seawall separating the ocean from the plant site to prevent ground water from seeping through. It said it now intended to solidify a larger part of the seawall with the chemical.
The March 2011 earthquake and tsunami knocked out cooling systems at the Fukushima plant, triggering fuel meltdowns and causing radiation leakage, food contamination and mass evacuations.
Tepco this month acknowleged that levels of radiation in groundwater had soared, suggesting highly toxic materials from the plant were getting closer to the Pacific.