Officials also have told the governments of Malaysia and Singapore that the sub made port calls to those countries while leaking the radioactive water, Navy officials said. The Houston also made stops in Guam and Hawaii.
Officials with knowledge of the incident could not quantify the radiation level but insisted it was "negligible" and an "extremely low level." The total amount of radioactivity that leaked while the sub was in port in Guam, Japan and Hawaii was less than a half of a microcurie (0.0000005 curies), or less than what is found in a 50-pound bag of lawn and garden fertilizer, the officials said.