The manager of the Fukushima No. 1 nuclear power plant has admitted to embarrassment that repeated efforts have failed to bring under control the problem of radioactive water, eight months after Prime Minister Shinzo Abe told the world the matter had been resolved.

Tokyo Electric Power Co., the plant's operator, has been fighting a daily battle against contaminated water since Fukushima No. 1 was wrecked by the March 2011 earthquake and tsunami.

Abe's government pledged half a billion dollars last year to tackle the issue, but progress has been limited.