No radioactive materials leaked from submarine: U.S. Navy.
The U.S. Navy said Thursday no radioactive materials leaked from its nuclear-powered submarine which was docked until Sept. 14 at a port in Kanagawa Prefecture.
The announcement came in response to the Japanese government's detection of such materials in sea water at Yokosuka port after the USS Honolulu left the port.
''The Commanding Office of USS Honolulu reported that there was no deliberate discharge of radioactive liquid from Honolulu while the ship was visiting Yokosuka,'' the U.S. Navy said.
After receiving a request from the Japanese government last month to investigate a possible leak, the navy had an independent naval investigator analyze the submarine's data and question the commander of the submarine.
The navy reported the investigation results to the Japanese government and the Yokosuka city government, it said.
Japan's science ministry said in late September that it has detected cobalt 58 and cobalt 60 in sea water near the port where the submarine was docked, although their amounts were extremely small and have not affected the surrounding environment or people.
The USS Honolulu had stayed at Yokosuka port from Sept. 7 to 14 and the test was conducted after the submarine left the port.
The materials, neither of which is found in nature, are manufactured radioactive isotopes. Cobalt 60 is used for medical or industrial purposes, but cobalt 58 has no such uses and is short-lived.
Since 1964, the science ministry has measured the amount of radioactive materials and radiation in areas near where nuclear submarines have been.