YOKOSUKA NAVAL BASE, Japan — For the third year in a row, no submarine was in port at Yokosuka Naval Base when the alarm sounded Tuesday morning signaling heightened amounts of radiation.

A simulated submarine was used for the city of Yokosuka’s annual “what if?” nuclear response drill. The practice tests communication and emergency response to elevated radiation levels.

An abnormal reading from one of four on-base Japanese monitoring posts started the drill at 9 a.m. The reading indicated double the normal level, jumped up to 100 times normal and kept increasing until it registered that approximately 2,400 times the normal amount of radiation was being emitted.

The Navy’s role, finished within 15 minutes, basically was to establish the source wasn’t one of the nuclear-powered U.S. submarines that occasionally dock in Yokosuka.

“Our part is mostly telephonic,” said Cmdr. John Wallach, Commander Naval Forces Japan spokesman. “We want to make sure their communication tree works and that we have quick, reliable means to pass information back and forth.”

The Ministry of Education, Culture, Sports, Science and Technology, which monitors the posts, notifies the city of an abnormal reading. The city then calls Yokosuka’s base liaison, which calls the Submarine Force 7th Fleet Command center. Once the submarine is checked out, the information is relayed back to the city.

That part of the drill was included “to confirm U.S.-Japan cooperation,” said Katsumi Marumo, Yokosuka city’s disaster-prevention division chief. “In regards to that part, it went smoothly.”

When the Navy’s part ended, the city’s radiological accident response began.

The city also practiced drills including resident evacuation, medical treatment procedures and information gathering.

In all, some 1,000 people from Japanese government agencies, self-defense forces, Yokosuka city, the Kanagawa Prefectural Office, police agencies, medical associations and local communities took part, the city’s news release stated.

Added this year was an evacuation drill by kindergartners from Verny Park, across Truman Bay from the Ship Repair Facility, Marumo said. In their scenario, they were on a school field trip at the park when higher-than-normal radiation was measured. The children evacuated to inside a museum in the park, then were transported out by bus, Marumo said.

On Tuesday, the scenario’s “culprit” was found to be an industrial machine that X-rays welds at construction sites. The location of the machine’s location was “undetermined,” Wallach said.

The city began the nuclear response practice in 2002. In that scenario, the leak was from a U.S. submarine.

The Navy didn’t participate that year, stating that in 55 years of its nuclear power program, not one accident has occurred involving a nuclear propulsion system.

author picture
Hana Kusumoto is a reporter/translator who has been covering local authorities in Japan since 2002. She was born in Nagoya, Japan, and lived in Australia and Illinois growing up. She holds a journalism degree from Boston University and previously worked for the Christian Science Monitor’s Tokyo bureau.

Sign Up for Daily Headlines

Sign up to receive a daily email of today's top military news stories from Stars and Stripes and top news outlets from around the world.

Sign Up Now