LONDON, Nov 21 (Reuters) - The head of Russia's state-run atomic energy agency, Rosatom, warned on Monday there was a risk of a nuclear accident at the Zaporizhzhia nuclear power plant, Europe's largest, following renewed shelling over the weekend.The IAEA has called for the creation of a security zone around the plant, something Likhachev said would only be possible if it was approved by the United States."I think the large distance between Washington and Zaporizhzhia should not be an argument for the United States to delay the decision on a security zone," Interfax quoted him as saying.The Rosatom head also said it appeared Kyiv was willing to "accept" a "small nuclear accident" at the nuclear power station"This will be a precedent that will forever change the course of history.Therefore everything must be done so that no one has in their minds to violate the security of the nuclear power plant," TASS quoted him as saying."