Updated, 16.25
JAPAN’S NUCLEAR AUTHORITIES have declared a state of emergency at a second nuclear power plant in the country, after its operator reported an unexplained increase in the level of radioactive readings in its surrounding area.
Authorities have declared the lowest possible state of emergency – a level 1 alert, with level 7 being the most severe – at the Onagawa plant, near Ishinomaki in the Miyagi prefecture that has borne most of the damage from Friday’s earthquake and the resulting tsunamis.
In a statement, the UN’s International Atomic Energy Agency said it had been informed by Tokyo Electric Power Company (TEPCO), which operates the Onagawa plant, that the level of radioactive readings in the area outside the plant had been “exceeding allowed levels”.
Those levels are around 700 times the normal level, TEPCO added, but were still considered low.
This evening news emerged that a cooling system at another plant, the Tokai 2 nuclear station between Fukushima and Tokyo, had also failed – bringing to four the number of power stations at which there have been significant cooling failures.
In the case of the Tokai plant, however, the BBC reported there was no pressing danger because the plant was automatically shut down as a precaution following Friday’s earthquake. A nuclear accident occurred at Tokai in 1999.
The IAEA has said that the three reactor units at Onagawa station were “under control”, adding that the state of emergency was declared as a legal requirement.
It has begun investigations to identify the source of the radiation – as Japan’s nuclear authorities suggested that yesterday’s blast at Fukushima I, which is about 120km away, might be to blame for the scattered radioactive substances being recorded near Onagawa.
In a separate statement, the IAEA confirmed that one worker had died at the Fukushima II power plant, in an accident involving a crane operation that injured four others.
Of the four reactors present at that plant, three reactors remain operational – albeit under strict supervision – while a fourth unit was in “a safe, cold shutdown” following the collapse of cooling systems.
Three of the six reactors at Fukushima I, the site of yesterday’s explosion at one containment building, are currently being cooled by the injection of seawater mixed with boron as a state of emergency – level 4 – persists there.
After the hydrogen explosion at the containment building for reactor 1, authorities confirmed that the nuclear core of reactor 3 had been briefly exposed following a minor leak, but that there was no immediate danger of a meltdown.
Reactor 3 is the only one at Fukushima I to contain both plutonium and uranium – a mixture that one nuclear architect said was particularly potent, and could cause untold environmental damage if it was to leak.
The two Fukushima plants and the Onagawa operation are ‘boiling water reactors’, which can be thought of as operating in a similar manner to a kettle – where the core reactor must be kept submerged in order to avoid overheating and melting.
Even if a meltdown was to occur – as it is reported to have done at reactor 3 at Fukushima I – the nuclear material may not necessarily leak into the wider environment, given the number of containment structures inside which each main reactor is housed.
19 people from the areas surrounding the Fukushima I plant have been hospitalised for radiation exposure.
As telephone and internet connections are slowly restored around Japan, new footage has emerged of the extraordinary tsunami that struck the country’s eastern coast on Friday.
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