Uncovered Fuel Rods Pose Greatest Danger Now

http://english.kyodonews.jp/news/2011/03/78734.html

DIRECT QUOTES FROM KYODO NEWS

Japan police to douse spent fuel rods with water at Fukushima plant
TOKYO, March 17, Kyodo

Tokyo police plan to use a water cannon truck to attempt to cool a spent fuel rod pool Thursday in a bid to contain the disaster at the troubled Fukushima No. 1 nuclear power station in Japan.

The building housing the No. 4 reactor suffered what appeared to be a hydrogen explosion early Tuesday following the devastating earthquake and tsunami last week. A fire also broke out Wednesday there.

In the face of the unprecedented nuclear crisis, the focus is now on how to cool the possibly overheating pools that store spent nuclear fuel rods at the No. 4 as well as No. 3 reactors.

Unless the spent fuel rods are cooled down, they could suffer damage and emit radioactive materials.

The government earlier studied a plan to deploy Ground Self-Defense Force choppers to spray water over the spent fuel pools, but the Defense Ministry said Wednesday afternoon it had given up on the idea due to the high radiation level.

The U.S. military, meanwhile, will operate a Global Hawk unmanned high-altitude reconnaissance aircraft, possibly on Thursday, to take images of the inside of the building that houses the No. 4 reactor, according to Japanese government sources.

Among the six reactors at the Fukushima No. 1 nuclear plant operated by Tokyo Electric Power Co., part of the No. 2 reactor's containment vessel, key to enclosing harmful radioactive substances, suffered damage in the pressure-suppression chamber connected to the vessel following Tuesday's apparent hydrogen explosion.

An estimated 70 percent of the nuclear fuel rods have been damaged at the plant's No. 1 reactor and 33 percent at the No. 2 reactor, Tokyo Electric said Wednesday.

The cores of the No. 1, No. 2 and No. 3 reactors are believed to have partially melted with their cooling functions lost in the wake of Friday's magnitude 9.0 earthquake and tsunami.

The government's Nuclear and Industrial Safety Agency said Wednesday that the water level had dropped in the No. 5 reactor, which was not in service when the killer quake jolted northeastern Japan, posing the risk of overheating. The agency said it will closely monitor data on the reactor to prevent the problems that occurred at other reactors.

The government has set the evacuation zone covering areas within a 20 kilometer radius of the plant.