Thursday, March 21, 1996 LONDON (Reuter) - More than 30 million people could be contaminated by radioactivity sweeping down rivers from the Chernobyl nuclear power station, scientists reported Thursday. They said floods were carrying downstream radioactive waste dumped around the reactor 10 years ago when it exploded and caught fire in the world's worst nuclear accident. The New Scientist magazine reported the findings of a team of 59 scientists from eight countries led by Umberto Ensone of Italy's Environment Protection Agency. Their investigation showed the lake most contaminated by radioactivity from Chernobyl was 155 miles from the site. Fish in Russia's Lake Kojanovskoe had radiation levels 60 times above European Union safety norms and all fishing should be banned, the scientists said in their report, financed by the European Commission. They said reservoirs downstream from the damaged reactor provide drinking water for nine million Ukrainians as well as irrigation and fish for another 23 million.