Tokyo Electric Power Co. said Friday that an estimated 20 trillion to 40 trillion becquerels of tritium from the Fukushima No. 1 nuclear plant may have flowed into the Pacific Ocean since May 2011.

The utility reported the estimate Friday to the Nuclear Regulation Authority after recently admitting that toxic water from the emergency cooling system set up after the nuclear crisis began on March 11, 2011, is leaking into the sea.

Nevertheless, Tepco said the size of the release is roughly in the allowed range of 22 trillion becquerels a year but acknowledged it didn’t take place in a controlled manner. Tritium has a half-life of about 12 years.

Since it doesn’t know when the leak began, the utility has assumed the beginning was in May 2011, after it attempted to stop the toxic water from entering the ocean when it was discovered in April 2011.

The constant injection of water that is needed to keep the damaged reactors cool after the core meltdowns of March 2011 are generating a new radiation crisis at the plant that officials appear unable to solve without tainting the ocean and marine life.