OSLO — Norway said on Wednesday that elevated levels of radioactive caesium (Cs-137) it had detected near the Arctic border with Russia were likely due to a forest fire near Chornobyl in Ukraine, the site of the world’s worst nuclear accident. The Norwegian Radiation and Nuclear Safety Authority (DSA) said in a statement on Tuesday that it had measured “very low” levels of radioactive caesium at Svanhovd and Viksjoefjell near the Arctic border with Russia. The authority detected elevated levels of radioactive caesium at Svanhovd from Sept. 9-16 and at Viksjoefjell from Sept. 5-12, but the levels didn’t pose a risk to humans or the environment, it added. …”This time it is most likely that the forest fire around Chornobyl is to blame.” …On April 26, 1986, Reactor No. Four of the Soviet Union’s Chornobyl nuclear power plant… released large amounts of radiation into the atmosphere.