Japan: Robots detect dangerous spike in reactor 3 radiation

Japan Times ^ | 04/18/11 | Kanako Takahara

[TigerLikesRooster]

Robots detect dangerous spike in reactor 3 radiation

French-style air coolers eyed in effort to bring down the heat

By Kanako Takahara

Staff writer

Remotely operated robots detected a high radiation level of up to 57 millisieverts per hour Monday in a reactor building of the crippled Fukushima No. 1 nuclear plant, an obstacle that hinders workers from engaging in key repair work inside for long hours, the government's nuclear watchdog said Monday.

On Sunday, the U.S.-made robots checked the radiation level, temperatures and oxygen concentrations of reactor units 1 and 3 to see if workers can go deep inside for critical repairs of the crippled cooling systems.

In the No. 3 reactor building, the robots detected a radiation level between 28 to 57 millisieverts per hour on the ground floor, while that of the reactor 1 building was between 10 to 49 millisieverts per hour.

"It's difficult to work for a long time under these conditions," said Hidehiko Nishiyama, spokesman at the Nuclear and Industrial Safety Agency.

The maximum allowable radiation for worker at the reactors is 250 millisieverts annually. The limit was raised from the original regulation of 100 millisieverts given the graveness and urgency of the crisis.

This means each worker can work only for five hours or less inside the reactor building, given the strong radiation detected. Many have already been exposed to radiation 100 millisierverts or more.

On Saturday, workers detected 270 millisieverts per hour at the south side of the same floor of the No. 1 unit before the robot went inside the north side of the same building, Tepco said.

[TigerLikesRooster]

P!

[scottinoc]

Danger, Will Robinson

[GonzoGOP]

On Saturday, workers detected 270 millisieverts per hour at the south side of the same floor of the No. 1

Those kind of radiation levels make this an environment for robots not humans. And they don't have it well mapped yet. If parts of the building are at 10, others at 50 and still others at 270 you need to get that mapped before you send humans in. You don't want to wander into a 270 zone where you can run up a serious dose in a matter of minutes.

Also as they start demolition they are going to stir up dust that is contaminated, driving the levels up. Time to give Robby the Robot a shovel and send him to work.

[Zuben Elgenubi]

"He's radiating, Jim."

[kidd]

In the No. 3 reactor building, the robots detected a radiation level between 28 to 57 millisieverts per hour on the ground floor, while that of the reactor 1 building was between 10 to 49 millisieverts per hour.

In the 1980s, US radworkers frequently entered similar fields to inspect (or "jump") steam generators. (This practice has been greatly reduced with robots).

During such entries, the radworker would be strictly timed with a technician and a stop watch who would yell "get out" as the estimated exposure limit was approached.