Decommissioning work is still ongoing at the TEPCO Fukushima Daiichi Nuclear Power Station.

Fuel debris remains in the Unit 1–3 reactors, but cooling water is being contiguously injected and keeping the debris stable. Fuel debris is the cooled, solidified matter (a mixture of melted fuel rods and fuel cladding material) that remains after a meltdown (when a reactor core cannot be cooled and overheats, causing the fuel to melt). Surveys conducted inside the reactors and analysis of the incident suggest that there was no external leakage of molten fuel during the accident.

The radiation levels of the air and water around the perimeter of the power station are monitored regularly, and the impact on nearby communities is deemed negligible. Systems have been put in place to quickly report and deal with any increases in the ambient dose or the density of radioactive material in the air.

Reference
Agency for Natural Resources and Energy, METI : Important Stories on Decommissioning 2019 Ministry of Economy, Trade and Industry : Mid-and-Long-Term Roadmap towards the Decommissioning of TEPCO's Fukushima Daiichi Nuclear Power Station Units 1-4