Japan's nuclear crisis is 'uncharted territory'

The cooling functions stopped and water levels fell at the No.2 reactor at Japan’s Fukushima Daiichi nuclear plant on Monday, a Japanese news agency reported, fueling fears of a deepening nuclear crisis in the wake of the devastating earthquake and tsunami that battered the country on Friday.

Jiji news agency on Sunday quoted Japan's Tokyo Electric Power Co (TEPCO) as saying it was preparing to flood the No.2 reactor with seawater in a last-ditch effort to cool it down, after similar efforts for the No.1 and No.3 units at the Fukushima Daiichi site.

In pictures: Japan quake

The cooling functions at the Fukushima nuclear site, located 250 kilometres (120 miles) north of Tokyo, were knocked out by Friday’s 8.9-magnitude earthquake.

After an explosion at the No.1 reactor over the weekend, TEPCO announced another explosion on Monday at the No.3 reactor building. But the blasts were not thought to have blown the main reactor vessels.

Emergency crews risked their lives to prevent a meltdown of the cores at the sites. If they fail, the containers that house the core could melt, or even explode, releasing radioactive material into the atmosphere.

“This second explosion has really shaken people in Tokyo,” said Philip White of the Tokyo-based Citizen’s Nuclear Information Centre (CNIC). “It’s important to bear in mind that the No.3 reactor uses mixed oxide or mox fuel, which contains plutonium and is more dangerous.”

“Plutonium has a lower melting point and has longer-lived isotopes,” White told FRANCE 24. “It is worrying that this reactor should go.”

A large-scale radiation leakage is unlikely from the failing nuclear plants, Chief Cabinet Secretary Yukio Edano told a news conference on Monday, while Japan's nuclear safety agency said there was "no possibility of a Chernobyl" style accident.

Cooling with seawater

Nuclear experts said it was probably the first time in the industry's 57-year history that seawater has been used in this way, a sign of how close Japan may be to a major accident.

In an interview with Scientific American, physicist Ken Begeron said even nuclear catastrophe experts like himself were moving quickly into “uncharted territory”.

He explained that both the offsite and onsite electric power sources that are supposed to ensure constant cooling of the Fukushima reactors were cut because of the dual earthquake and tsunami strike. The loss of electrical power forced facility operators to dump seawater on the reactors in order to cool the fuel.

“We're in a land where probability says we shouldn't be,” Begeron added.  "And we're hoping that all of the barriers to release of radioactivity will not fail.”

Dumping seawater to cool the reactors and prevent a dangerous meltdown was a desperate move, experts explained. The corrosive seawater may avert large-scale radioactive contamination, but will render the facility inoperable in the future.

20km evacuation zone

Authorities evacuated over 170,000 residents within 20 kilometres of the Fukushima Daiichi and adjacent Fukushima Daini sites and began screening the public for potential contamination, according to the World Nuclear Association.

Out of about 100 residents evacuated by buses, nine people were found to have been exposed, Japan's Nuclear and Industrial Safety Agency (Nisa) was quoted by the World Nuclear Association as saying. Overall, more than 1,500 people had been scanned for radiation exposure in the area, officials said.

“At this stage we are far from our worst fears, radiation releases are quite low” the CNIC’s White said. “But the reactors are unstable and no one can say they won’t breach the containment in large quantities. It can happen.”