The 97,000-ton George Washington, a nuclear-powered carrier of the U.S. Navy, arrived at its new home port, Yokosuka, Thursday. The flattop carrying more than 70 aircraft is the fourth U.S. carrier to be stationed there since 1973 — after the Midway, the Independence and the Kitty Hawk, all oil-powered. The arrival begins the first permanent deployment of a nuclear-powered carrier at a Japanese port.

Both Tokyo and Washington describe the deployment as a symbol of the strong alliance between the two countries. Of the U.S. Navy's 10 nuclear-powered carriers, the George Washington is the only one that uses a foreign port as its home port. Its arrival comes at a time when people's fear of a possible nuclear accident has heightened due to a fire in May aboard the George Washington, caused by unauthorized smoking, and the recent revelation that the nuclear-powered attack submarine Houston leaked low-level radioactive water for two years.

The Japanese government has increased the number of radioactivity monitoring posts in Yokosuka from four to 10. The Yokosuka city government has signed a disaster-prevention agreement with the U.S. Navy. But Yokosuka citizens will not be included in disaster-prevention training. Both the Japanese and U.S. governments should make efforts to make a disaster-prevention setup truly effective.

The central government has a manual describing how to cope with a nuclear accident. If an irregular level of radioactivity is detected, the Nuclear Safety Commission would advise the government on necessary measures, including those for evacuating citizens and halting ship navigation around Yokosuka.

The problem is that the George Washington's two reactors, each with an output of 600,000 kW, are veiled in secrecy. It is known that fuel for the pressurized light-water reactors is changed roughly every 25 years. But the hull and reactor designs, and information on reactor operation and maintenance, have not been disclosed. The government should make efforts to get as much cooperation as possible from the U.S. side. It also must do its best to ensure that the manual procedures will work in case of an emergency.