The Japanese government says highly radioactive areas around the crippled Fukushima nuclear plant will remain no-go zones for decades after the damaged complex is stabilised.

Authorities say they plan to bring the stricken nuclear plant to a state of cold shutdown early next year.

But with some areas near the complex continuing to show high levels of radioactive contamination, the government says it is unavoidable that some places will remain no-go zones.

Japanese newspaper The Daily Yomiuri reports government sources have said it could be ‘several decades’ before the area is considered safe to enter.

For the first time, the government has released figures revealing that many communities within 20 kilometres of the complex have contamination levels up to 500 times higher than safety limits.

The radiation readings were taken in 50 locations within a 20-kilometre radius of the Fukushima nuclear plant.

Based on that data, the government has released estimates of the annual dose of radiation residents would be exposed to.

It found that in one town, Okuma, people would receive a dose of 508 milisieverts per year – more than 500 times the acceptable limit.

At more than half the locations it was more than 20 times the limit.

Tokyo Institute of Technology’s associate professor of radiobiology, […]