- Bringing Up Turing’s ‘Child-Machine’ (revised) – PhilSci-Archive
- Alan Turing Year / “Bringing Up Turing’s ‘Child-Machine’ “
- Fukushima Current Status: “cold shutdown” is cold comfort — remaining problems are “immense”
- Brief Hiatus
- Fukushima Daiichi Nuclear Plant Current Situation: An analogy (UPDATED on May 22nd, May 30, June 21, July 3rd, August 4th, September 22nd, and October 17th, 2011)
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I’m back from my hiatus due to an emergency at home. Today TEPCO announces that a status called “cold shutdown” has been achieved at the Fukushima-Daiichi nuclear electrical-generating station complex I have blogged so much about in the past.
Well, they had hoped to do this by year’s end. Yet, I doubt it is actually the milestone originally envisioned when the goal was set. I don’t think the term ‘cold shutdown’ was originally meant, or has ever before been used, to describe a plant that is in such a condition: a plant with molten fuel outside the reactor vessel, a plant still producing radioactive effluent that it cannot accommodate, a plant needing a tent-like cover over it that will need to be replaced repeatedly, and so on.
The Wall Street Journal article “After Nuclear Milestone: A Long Road” seems to me to be clear-eyed and very informative. The authors know what they don’t know and shouldn’t be trying to speculate about; they write that:
Indeed, there can be few firm declarations about the plant’s status. Daiichi’s reactors are littered with debris. Many measurement and control systems are on the blink. Radiation levels are too high for people to get close to the reactors, leaving engineers and scientists to make important judgments using computer simulations, scattered bits of data and guesses.
This modeling has led to dire assessments, such as Tepco’s announcement late last month that fuel in the complex’s No. 1 reactor likely melted completely through its pressure vessel and into a cement floor of the surrounding containment vessel. Hard information is so scarce that Tepco officials say they still aren’t sure how the meltdowns unfolded and about the current state of the nuclear fuel.
Even if cold shutdown is attained, it will take decades for isotopes to decay to safe levels, and to remove the last fuel and completely dismantle the plant. For now, the unknowns are so great that authorities aren’t even sure how to start tackling some of the biggest problems, which include locating and stopping the flow of toxic water and removing the melted nuclear fuel.
The full article is here: http://online.wsj.com/article/SB10001424052970204336104577096281099680526.html
I highly recommend the WSJ above for its comprehensiveness and its usefulness in providing an overview. There are links and videos in the article.
ADDED after 8 pm: Nature has an article basically in line with the above. It has a nice discussion of what the term “cold shutdown” was meant to refer to. http://www.nature.com/news/fukushima-reaches-cold-shutdown-1.9674
The IAEA has a page on the topic, too, here: http://www.iaea.org/newscenter/focus/fukushima/
ADDED around 10 AM: Here is a very interesting, descriptively colorful pooled account of the site on the November day that the media were allowed to visit: “A Look Inside Fukushima Daiichi”, illustrated with slides so you get some idea of what a visit would be like.
Due to a family emergency on October 19th, I have not posted in awhile. It may be a few more weeks until I return to posting again.
Fukushima Daiichi Nuclear Plant Current Situation: An analogy (UPDATED on May 22nd, May 30, June 21, July 3rd, August 4th, September 22nd, and October 17th, 2011)
I’ve updated this post, adding the following today:
Applying what we’ve learned from the accident at Fukushima: what’s being done?.