WASHINGTON (CNN) -- Water with trace amounts of radioactivity may have leaked for months from a U.S. Navy nuclear-powered submarine as it traveled around the Pacific to ports in Guam, Japan and Hawaii, Navy officials told CNN on Friday.
The USS Houston arrives in Pearl Harbor for routine maintenance, during which the leak was found.
The leak was found on the USS Houston, a Los Angeles-class fast attack submarine, after it went to Hawaii for routine maintenance last month, Navy officials said.
Navy officials said the amount of radiation leaked into the water was virtually undetectable. But the Navy alerted the Japanese government because the submarine had been docked in Japan.
The problem was discovered last month when a build-up of leaking water popped a covered valve and poured onto a sailor's leg while the submarine was in dry dock.
An investigation found a valve was slowly dripping water from the sub's nuclear power plant. The water had not been in direct contact with the nuclear reactor, Navy officials said.
Officials with knowledge of the incident could not quantify the amount of radiation leaked but insisted it was "negligible" and an "extremely low level." The total amount 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.
The sailor who was doused, a Houston crew member, tested negative for radiation from the water, according to Navy officials.
Since March, the Houston had crisscrossed the western Pacific, spending a week in Japan and several weeks in both Guam and Hawaii, Navy officials said.
The Navy on Friday notified the Japanese government of the leak, the officials said, and told them it was possible the ship had been leaking while in port in Sasebo, Japan, in March.
While Japan has agreed to allow U.S. nuclear-powered ships in Japanese ports, the decision was a not popular in Japan.
The Houston incident comes at a time when the Navy is trying to smooth over a problem with a nuclear-powered aircraft carrier.
The USS George Washington was due to replace the aging, conventionally powered USS Kitty Hawk this summer as the United States' sole carrier based in Japan.
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UPDATE: AP
8/1/2008 11:36:00 PM
Japan warned of possible nuclear leak from US sub
By MARI YAMAGUCHI Associated Press Writer
The U.S. Navy has warned that a nuclear submarine may have had radioactive leaks during recent port calls in Japan's south, the country's Foreign Ministry said Saturday.
Japan's Foreign Ministry said in a statement that it was informed by the U.S. Navy that a small amount of radiation might have leaked from the nuclear-powered USS Houston as it traveled around the Pacific.
The Houston made calls in March and April in the southern Japanese naval ports of Sasebo and Okinawa.
The ministry said leaked radioactive cooling water was detected during routine maintenance on the Houston in Hawaii in June and it was believed to have posed no threat to humans or the environment.
Sasebo city official Akihiro Yoshida said the government monitoring during the submarine's port calls showed no abnormal increase of radioactivity in the area's waters.
"Still, we are rather concerned," Yoshida said.
The incident comes just weeks ahead of the arrival of the U.S. nuclear-powered aircraft carrier USS George Washington in Yokosuka, just south of Tokyo.
The ship's arrival was originally set for August under a Japan-U.S. security alliance, but is being delayed until late September because of a fire aboard the vessel in May. The George Washington is relieving the soon-to-be decommissioned USS Kitty Hawk and will be the first U.S. Navy nuclear powered vessel to station permanently in Japan.
The George Washington's deployment had already triggered protests and the fire escalated concerns that many Japanese have about nuclear power.
In Honolulu, U.S. Pacific Fleet spokesman Capt. Scott Gureck said Friday the amount of radioactivity released into the environment from the USS Houston at each stop was less than one half a microcurie _ a negligible amount equivalent to the radioactivity of a 50-pound bag of fertilizer.
The Navy discovered the leak July 17 when a gallon of water spilled on a shipyard worker's leg from a valve while the submarine was in dry dock for routine maintenance at Pearl Harbor.
An investigation showed water may have been slowly leaking from the valve since March as the Los Angeles-class submarine traveled around the Pacific.
The Houston is based at Apra Harbor in the U.S. territory of Guam in the Western Pacific. The submarine sat in Pearl Harbor for about three weeks before it was dry-docked in mid-July.
