title: Corrections and clarifications.
abstract: The Random Sample item, "Russians, U.S. differ on Arctic sub threat" (25 June, p. 1881) should have said that the Sellafield nuclear reprocessing plant has dumped 1 million curies of cesium-137 (not plutonium) into the North Sea. The plant has dumped more than 18,000 curies of plutonium.