YOKOSUKA NAVAL BASE, Japan — “Hello? This is Kabaya. Good Morning. Yes? Yes? Radiation?”

The phone call to Yokosuka Mayor Ryoichi Kabaya’s office mobilized 140 people on a practice “what if” involving the USS George Washington before the nuclear-propelled aircraft carrier actually arrives in its new home at Yokosuka next year.

The scenario: Coolant water, including traces of radiation, leaked from the ship.

U.S. Navy and City of Yokosuka crews responded together, setting up a disaster headquarters, monitoring water and soil samples, and getting the word out to local residents and Japanese base workers.

It’s a big change from previous years, when the extent of the Navy’s participation in the city’s annual nuclear drill was basically a phone call saying it wasn’t one of its warships, and that the chances of a ship-caused nuclear accident was “highly unlikely.”

But the George Washington is slated to replace the 46-year-old USS Kitty Hawk in 2008, and the Navy wanted to show Japanese that it could work with them, said Submarine Group Seven spokesman Lt. Cmdr. Greg Kuntz.

“The George Washington is going to be forward-deployed here — it’s not going to be just visiting,” Kuntz said. “And in the unlikely situation that we have an incident, we wanted to show that we can work together with openness and cooperation.”

The City of Yokosuka also requested more Navy input in a series of talks about what would make them more comfortable with the carrier, and this year’s participation is a “logical progression” of that, Kuntz said.

Sharing information with the Navy improved initial response time and bettered “face-to-face” relations, Kabaya said. In previous years, the city was left with searching for a cause for a radiation source or waiting for a monitoring post to detect one, he added.

The drill involved 90 people from the city, Japanese ministries and Kanagawa Prefecture, plus 50 U.S. members, including 12 visitors from the Naval Sea Systems Command.

The George Washington was simulated pierside on the base, while the Japanese Coast Guard monitoring boat, the Kinugasa, took people to collect water and soil samples.

The drill ended with the news that it was only a small leak, with no more radioactivity than a banana.

“It was an extremely realistic scenario” based on 60 years of the Navy’s operation of nuclear reactors, said Commander Naval Forces Japan Rear Adm. James Kelly.

Naval ships have “the safest nuclear reactors in the world,” he said. Kelly ended the drill by “reporting” the incident and “apologizing” to the mayor for causing concern to the city and the residents.