The George Washington, a nuclear-powered aircraft carrier of the U.S. Navy, will arrive at Yokosuka on Thursday to replace the oil-powered Kitty Hawk. This will be the first time that a Japanese port serves as a home port for a nuclear-powered carrier. As the situation will be equivalent to installing a small nuclear power plant in a populated area close to the nation's capital, utmost care must be taken to prevent a nuclear disaster.

The carrier will spend several months a year at Yokosuka. It has two 600,000-kW reactors and is equipped with a multitier safety system. The U.S. Navy has said its nuclear-powered ships have never suffered a reactor-related accident and has given assurances that safety will be maintained.

But two incidents give cause for worry. On May 22, improperly stored flammable liquids were ignited in an engineering room of the George Washington, most likely by a lit cigarette. The fire raged for 12 hours, damaging some 80 of the 3,800 compartments and injuring 37 sailors. The incident, which delayed the carrier's arrival by about a month, demonstrates that an accident risk remains despite its safety system.

It also surfaced Aug. 1 that the Houston, a nuclear-powered fast-attack submarine, which visited Sasebo (Nagasaki Prefecture), Yokosuka and White Beach (Okinawa Prefecture), had leaked a tiny amount of radioactivity for two years. The U.S. Navy waited a week to notify the Japanese Foreign Ministry after the leak was confirmed and, in turn, the ministry failed to immediately notify local governments concerned.

The George Washington will shut down its reactors while at Yokosuka, and the number of radioactivity monitoring posts has been increased from four to 10. But Japanese officials are not allowed to inspect the ship. People will not be at ease until the government receives clear and transparent assurances from the U.S. Navy that it will fully cooperate on safety-related matters. The presence of the carrier, with its strong power projection capabilities, will also lead to the perception abroad that Japan has been incorporated further into the U.S. military strategy.