Japanese Reactor Research Educator – “What’s the point of cold shutdown now we know fuel is no longer sound?”

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As a radiation metrology and nuclear safety expert at Kyoto University‘s Research Reactor Institute, Hiroaki Koide has been critical of how the government and Tokyo Electric Power Co. (TEPCO) have handled the nuclear disaster at the Fukushima No. 1 nuclear plant.

Hiroaki Koide, an assistant professor at Kyoto University's Research Reactor Institute. (Mainichi)
Hiroaki Koide, an assistant professor at Kyoto University's Research Reactor Institute. (Mainichi)

Below, he shares what he thinks may happen in the coming weeks, months and years.


TEPCO says it is aiming to bring the No. 1, 2 and 3 reactors to cold shutdown by January 2012.

Cold shutdown, however, entails bringing the temperature of sound nuclear fuel in pressure vessels below 100 degrees Celsius.

It would be one thing to aim for this in April, when the government had yet to confirm that a meltdown had indeed taken place.

But what is the point of “aiming for cold shutdown” now, when we know that fuel is no longer sound? 


The nuclear disaster is ongoing.

Immediately after the crisis first began to unfold, I thought that we’d see a definitive outcome within a week.

However, with radioactive materials yet to be contained, we’ve remained in the unsettling state of not knowing how things are going to turn out.

Without accurate information about what’s happening inside the reactors, there’s a need to consider various scenarios. At present, I believe that there is a possibility that massive amounts of radioactive materials will be released into the environment again.


Contaminated water was found flowing through cracks near an intake canal, but I think that’s just the tip of the iceberg.


I believe that contaminated water is still leaking underground, where we can’t see it.

What can be done?

I believe immediate action must be taken to build underground water barriers that would close off the nuclear power plant to the outside world and prevent radioactive materials from spreading.


It’s doubtful that there’s even a need to keep pouring water into the No.1 reactor, where nuclear fuel is suspected to have burned through the pressure vessel.


Meanwhile, it is necessary to keep cooling the No. 2 and 3 reactors, which are believed to still contain some fuel, but the cooling system itself is unstable.

If the fuel were to become overheated again and melt, coming into contact with water and trigger a steam explosion, more radioactive materials will be released.


Recovering the melted nuclear fuel is another huge challenge. I can’t even imagine how that could be done.


With Fukushima, there is a possibility that nuclear fuel has fallen into the ground, in which case it will take 10 or 20 years to recover it.

We are now head to head with a situation that mankind has never faced before.

Source: nuclear-news.net, via Twitter search for Radiation
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