Tokyo ( CNN ) -- The meltdowns of three reactors at Japan 's Fukushima nuclear power plant may have happened more than two years ago , but the disaster remains a giant , unresolved mess . An earthquake in 2011 triggered a tsunami which slammed into the plant , disabling it . The threat of radiation forced neighbors to evacuate and many still ca n't return to their homes . Authorities face many challenges before they can make the facility safe again for the long term . Explainer : Fukushima update . Here are five of the biggest questions still out there : . 1 . How dangerous for your health is Fukushima ? Data published in August shows 44 out of 216,809 children under age 18 in Fukushima prefecture were diagnosed with thyroid cancer or suspected of having the disease . The figure is far higher than the international average but opinions are split as to whether this is because of the nuclear accident or because of more sensitive screening . Also , health experts say it takes years after radiation exposure to develop thyroid cancer , which suggests the cause of the cancer may predate the tsunami . Read more about Fukushima health effects . 2 . What can you do with radioactive water ? The most immediate problem for plant operator Tepco is the hundreds of tons of water poured over the damaged nuclear reactors every single day to keep the molten fuel cool . If the fuel is not kept cool , it could cause another disaster . That radioactive water then needs to be stored safely . But several on-site water storage tanks that were originally designed to be temporary have sprung leaks . Tepco said last summer that as much as 300 tons of toxic groundwater was seeping into the Pacific Ocean every day , sparking fears about radioactive contamination of fish , which are a major food source . Read more about the leaks . More about Japanese-spawned tuna caught off the U.S. 3 . Is it safe to remove spent fuel rods ? Tepco is just days away from starting to remove 1,500 irradiated spent fuel rods from a pool in reactor number 4 to a safer location . The building was damaged by a hydrogen blast after the disaster . Removing fuel from a severely damaged pool has never been attempted . Critics fear the building is unstable and any mistake could cause a new nuclear disaster . Read more about removing the fuel rods . 4 . How do you remove molten fuel in melted down reactors ? The radiation levels in reactors 1 , 2 and 3 are so high that the area is inaccessible to humans . No one knows for sure where the molten core is resting within the basements of the buildings and how far it has penetrated through their floors . The technology does not exist to remove this molten fuel . 5 . How do you stop running out of skilled labor ? Workers within the Fukushima nuclear power plant have a radiation exposure limit . Once they reach this limit they can no longer work on site and new workers need to be found . As time goes on , more experienced workers will reach their exposure limits , sparking concerns that available workers will have decreased skill levels .
Fukushima officials must figure out what to do with increasing amounts of radioactive water . There are questions about lingering effects for people near the facility during meltdowns . Comment: