Japanese utility giant Tokyo Electric Power Company might dump radioactive water, left over from the destroyed Fukushima Dai-Ichi nuclear power plant, into the Pacific Ocean as part of a $200 billion cleanup effort.

Thursday marked the 10-year anniversary of the Fukushima nuclear disaster, caused by a 2011 earthquake and tsunami, which was the worst nuclear accident since the one at the Chernobyl Nuclear Power Plant in 1986. Thousands of engineers, scientists, and others are still working on the nuclear cleanup.

Part of that includes finding a way to remove and safely store 880 tons of highly radioactive uranium fuel, as well as a larger mass of concrete and metal that fuel melted into during the accident. The job could take up to 40 years, according to the Japanese government.