The crisis at Japan’s crippled Fukushima nuclear facility may be cooling. There were no major disasters yesterday — for the first time in a week — and the site now has limited electrical power, which should allow the engineers to restart some of the pumps. The International Atomic Energy Agency also believes the situation in reactors 1, 2 and 3 is “relatively stable”.

But serious problems remain with unit 4, which contains spent a couple of hundred nuclear fuel rods in a deep concrete pool that is either empty or very low in water. The IAEA confirmed last night the roof of this building has indeed been blown off, so there is nothing to prevent radioactive material being spewed into the atmosphere if the fuel heats up so much that it melts, along with its cladding.

The London-based World Nuclear News warned a few hours ago:

“The high levels of radiation and presence of hydrogen at unit 4 strongly indicate that fuel is uncovered and suffering damage in the pond…”

This explains why units 3 and 4 were water bombed yesterday, even though radiation levels had previously been judged too high for the Japanese Defence Force to operate. Says WNN:

“With such serious damage to the reactor buildings it is thought that radiation from further degradation of stored fuel at units 3 and 4 would be released to the environment unchecked.”

Or as one anonymous nuclear expert tells The New York Times, yesterday’s actions were a sign all else has failed:

“What you are seeing are desperate efforts — just throwing everything at it in hopes something will work. Right now this is more prayer than plan.”

We now have the first account of what it was like inside the nuclear plant when the tsunami hit. Michiko Otsuki is one of 800 workers evacuated from the complex on Monday, three days after the tsunami struck. Shortly after being sent home she posted a graphic description of what had happened on the night, while defending the Tokyo Electric Power Company and her fellow workers.

“Everyone has been flaming TEPCO,” writes Otsuki. “But the staff have refused to flee, and continue to work even at the peril of their own lives. Please stop attacking us… Everyone at the plant is battling on without running away.”

Mitsuko’s blog was first posted on Tuesday on the Japanese social networking site Miki (it has since been taken down) then picked up and translated by Singapore’s Straits Times, which has published her harrowing account:

“In the midst of the tsunami alarm (last Friday) at 3am in the night when we couldn’t even see where we were going, we carried on working to restore the reactors from where we were, right by the sea, with the realisation that this could be certain death.

“The machine that cools the reactor is just by the ocean, and it was wrecked by the tsunami. Everyone worked desperately to try and restore it. Fighting fatigue and empty stomachs, we dragged ourselves back to work.

“If we could not recover the cooling system, the second plant would have exploded as the first one. But we, TEPCO (Tokyo Electric Power Co.) could manage to prevent it.

“All of us have been working hard without thinking of their own lives.”

At the time of writing, Otsuki’s boyfriend was still inside the crippled reactor, working in appalling conditions with the rest of the “Fearless Fifty”. Five workers at the Fukushima plant (including some of the Fifty) are now known to have died, while 22 have been injured. Most have been hurt in explosions. None has so far been seriously affected by radiation.

News today is that some 360 workers have been allowed back on site because radiation levels on the perimeter are falling. At 4pm yesterday it was down to 0.64 millisieverts per hour — one-tenth the dose from a typical CT scan or powerful X-ray. Nine hours earlier it had been more than twice that level. And roughly 21 hours before it had been double that again.

But despite this improvement on the perimeter, it seems emergency teams can only get in close to the problem reactors — 3 and 4 — for short periods because radiation levels there are massively higher. As World Nuclear News reported a few hours ago:

“The peak of radiation on site is near unit 3, where levels of 400 millisieverts per hour have been recorded. Dose limits to workers under emergency regulations have been raised to 250 millisieverts from 100 millisieverts after which they may not return.”

In other words, a 40-minute mission would deliver the maximum dose workers are allowed to receive. They would then be forced out of action.

Radiation levels around unit 4 are said to be lower, at around 100 millisieverts per hour, but that’s still too high for workers to get in close for long, and there is reason to suspect that levels may actually be higher in that army chopper crews couldn’t operate there yesterday. WNN reports: “One attempt was made to douse unit 4 but pilots drew back after encountering high levels of radiation.”

According to WNN, the water bombing of Unit 3 was not a success anyway:

“Two army helicopters made four attempts to drop seawater on unit 3, but this did not appear accurate enough to be effective. TEPCO said in a news conference that radiation readings had dropped from 3.78 millisieverts per hour to 3.75 millisieverts per hour, so the effect at present seemed marginal at best.”

TEPCO also tried to send in 11 fire trucks with high-pressure hoses, but this also appears to have offered little chance of success, because they were trying to shoot water through holes in the side of the reactor building. However, TEPCO claims to have “delivered” 30 tonnes of this water into (or onto) unit 3, but some 500 tonnes is said to be needed. It sprayed little or none into unit 4.

So little or no progress has been made with reactor 3 or the spent fuel pool at reactor 4, which is still a “major safety concern”. The good news is that the fuel in pool 4 has been there for 100 days, so it is generating less heat than fresh fuel would. The bad news is the authorities still haven’t found a way to fix the problem.

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Peter Fray
Peter Fray
Editor-in-chief of Crikey
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