Japan facing a nuclear catastrophe

that of reactor no. 1. Chief Cabinet Secretary Yukio Edano said on Sunday that water levels within the pressure vessel could no longer be confirmed to be increasing and that there was a “high possibility” that a valve used to vent steam was malfunctioning. Earlier in the day, Tepco had warned that an explosion like that at reactor No. 1 was possible.

A state of emergency has also been declared at the nearby Fukushima-Daini plant, where preparations to vent steam to reduce pressure have been drawn up but have not yet been implemented. More than 200,000 people have been evacuated from the vicinity of the two nuclear plants, although the Japanese government continues to stress that the radiation known to have leaked thus far poses little risk to human health.

The difficulties at the nuclear power plants, as well as other power generation facilities, mean that rotating power outages will be imposed across Japan as of Monday.

As fears grow of an explosion at the number 3 reactor in the Fukushima-Daiichi nuclear power plant, Japanese prime minister Naoto Kan said in a press conference that the disaster was the worst since the atomic bombing of Hiroshima and Nagasaki in the Second World War.

Unlike the uranium-based Fukushima number 1, the number 3 reactor uses a mixture of plutonium oxide and uranium oxide. In the event of a meltdown, plutonium is considered more dangerous than uranium alone because of its increased volatility and its reactive, “neutronic” effects.

Michael Bluck, a nuclear engineer at Imperial College London, told New Scientist that plutonium is used because it increases the efficiency of power generation. “It improves the burn up, so you get more energy out of the fuel than if you just use uranium dioxide (UO2). Plutonium dioxide enhances burn up in normal situations in a controlled reactor, so it may result in even greater heat generation in the event of a meltdown than is the case with UO2 alone. It’s why plutonium is used in nuclear weapons, because it is more reactive and produces more energy.”

 

Bluck notes that plutonium is produced anyway in a “UO2 only” reactor, as part of the fission process. Adding plutonium at the beginning just gives us more.

 

The danger is that in the event of a meltdown there would be even greater generation of heat, with the additional demands of cooling. Metallic plutonium is a serious fire hazard, Bluck added, further complicating the situation.

To prevent the catastrophe of a meltdown, boric acid — a water solution containing boron — is being pumped into the number 3 reactor. Boron is used because it captures neutrons and reduces the risk of a fission chain reaction. It is being pumped with sea water into the reactor.

Japan generates about a third of its electricity from nuclear power.

Meanwhile, the Japan Meterological Agency warned that there is a 70 per cent chance of a magnitude-7 aftershock striking the country in the next three days. It said there is a 50 per cent risk over the three subsequent days.