Saturday, March 12, 2011

Fukushima: What I Think I Know So Far

Daybreak and Explosion

First thing this morning I saw the video of an explosion at the Fukushima Daiichi 1 reactor. I spent much of today trying to figure it out. There was clearly a hydrogen fire (you can see the thin blue flames rising rapidly at about 24 seconds into the video.) Beyond that, all was confusion.

The Japanese said that containment was not breached. Others said that the top of the reactor building seemed to be missing: if that wasn't "breaching containment," what was? Meanwhile, the Japanese also talked about the turbine building, and hydrogen fires in turbine buildings are pretty common. (Generators are cooled with hydrogen.) Though I no longer think the explosion is due to a generator fire, a fire in the turbine hall is still mentioned as a possibility in a recent New York Times article. (The turbines and generators are in the same building, called the turbine hall.) Atomic Insights blog also thought the explosion might be in the turbine hall. This blog also has a very informative discussion.

It's been that sort of a day. A day in which it has been very hard to figure out what is happening. When reasonable people don't know WHAT exploded, it's hard to move on from there.

Some Tentative Conclusions

Turns out that the NEI site is probably closest to correct. The outer containment building was breached in the explosion, but the inner containment of the core is intact. They are flooding the inner core with seawater and boron, which will ruin the reactor. Of course, the hydrogen fire probably means the reactor is ruined already: you don't get enough hydrogen to explode unless the fuel is uncovered and overheated.

Speaking of explosions, the top of the reactor building is sort of neat-looking. I mean, it looks too neat. The explosion goes down to a certain level, then stops, nice and even. This puzzled me, though nobody had mentioned it. However, in the comments on the Capacity Factor blog, I found this explanation: The walls that have been destroyed are actually curtain walls of the reactor building steel superstructure (which is seen on image, more or less intact). The containment and the reactor vessel are safe

That explains a lot. The containment part probably begins below those curtain walls.

All day has been like this. Trying to figure out the questions to ask (why such a neat line after an explosion?) and then trying to get the answers.

What Does It All Mean?

I don't know. The Japanese are distributing iodine, which doesn't sound good. On the other hand, when I visited Japan, I saw many people walking about with face masks to prevent disease spread. There wasn't a single piece of garbage on any street. The culture of Japan, as far as I could tell, is very organized, clean, and willing to take precautions. So maybe the iodine is a precaution. But maybe the iodine is a symptom that things are going very wrong. I simply do not know.

I continue to recommend the ANS Nuclear Cafe site for updates. It contains links to many other sites, including English-language Japanese television. In general, the New York Times has some of the best coverage in the main-stream media. I also recommend this thoughtful and balanced article A Japanese Three Mile Island, by Christine Russell at The Atlantic.


Anonymous said...

Thanks for the update. I had no idea that hydrogen was used as a coolant for the generators, and so I thought a hydrogen explosion must have been from hydrogen evolved from the core (i.e., very bad news). This is still bad news, but at least not as bad as it could be. I'll wait for the after incident inspection report to come out.

Anonymous said...

Martin Langeveld said...

Sunday morning and things have changed again ....

My last comment to your previous post said we're now dealing with 6 crippled reactors in Japan, but according to this Australian blogger there may be 7 in total:

There are several emerging lessons here for Vermont Yankee (which is, after all, what this blog is about):

First, while the emergency is unfolding, the authorities should get their story straight. VY, while it aims for a degree of openness, has a history of at least being disingenuous ("we have no underground pipes"). In Japan, through Saturday, people who have no idea what they are talking about issued statements that are clearly off base. This includes talk about the explosion being in the turbine building (pictures show clearly it was at the top of the reactor building), and talk about the concrete structure housing the reactor being destroyed (it was not — only the walls of the refueling floor area at the top of the reactor building were blown out).

If, in fact, the concrete quasi-containment building had been destroyed, the spent fuel pool would have been ruptured, creating a whole other set of hazards, including making it impossible to work in the proximity of the reactor. Since seawater pumping is going on, that is hopefully not the case.

On the other hand, the Japanese can hardly be blamed for failure to communicate, given that they have a trifecta of huge disasters going on.

The second lesson is that all fail-safe scenarios can fail. The root causes of the Japanese failure are not clear: the first problem was clearly that the entire grid went down, leaving these plants without power for pumps to cool the reactors. But why did the backup generators fail? Some have suggested it was the tsunami, which was a 23-foot wave in that area, but is that plausible? In any case, they failed, and then battery backups ran out of time, and then perhaps because of transportation issues, measures to bring in more generating or pumping capacity failed. I've come across one mention that says it's now the US Navy that's supplying the seawater pumping, but that's not confirmed.

At VY, the cooling backup "fail-safe" system includes a normal power connection to the grid; a secondary (underground) power connection to the nearby Vernon hydroelectric power station; on-site generators; and (I believe but I'm not sure) battery backup.

Scenarios at VY that disrupt everything up to the battery backup are implausible but not impossible. We have no idea what the 1000 or 10,000-year earthquake risks are in the area, but we know that the grid is vulnerable to disruption; the dam is 100 years old and would shut down the hydro station if breached; batteries last only so long; and the US Navy can't get up the Connecticut River. So what is VY's plan beyond the final fail-safes, assuming a regional catastrophe that disrupts not only power but transportation?

These are questions that wil be raised in the months ahead as Entergy attempts to make a deal with the powers that be in Vermont. Until 48 hours ago, they had a shot at a deal combining infrastructure upgrades, full funding of the decom fund, and a reasonable power deal. But now, they will have to overcome, as well, the political resistance that may come even from erstwhile supporters as a result of the Japanese disasters.

Anonymous said...

“The entire town was enriched by Tokyo Power,” Kumiko Fukaya, 48, said, referring to the company that runs the plants, the closest of which is three miles from her home. “I thought they picked a safe and secure location. So instead of opposing the nuclear plant, I felt more security. “Now I realize it’s a scary thing.”

Anonymous said...

How's that clean and safe thing workin' out for you?

Nuclear Crisis Spreads to 4th Plant

Anonymous said...

Good thing nothing has happened since yesterday...

Meredith Angwin said...

Hi Anonymous.

Clean and Safe thing is working fine for me. Nuclear has kept the skies clear of coal smoke, and the rivers clear of dams. So far, the problems in Japan have been two industrial accidents (with one person killed, and several more injured) and enough radiation released for precautions to be taken.

Also, delighted that you hang on every word of my blog, and are upset when I miss a day! I love to have fans!

Martin Langeveld said...

Reactor No. 2 at Fukushima Daiichi (situated between the two that have had hydrogen explosions) is now in the worst shape. They are removing wall panels from the refuelling floor to try to prevent a third explosion, but the fuel rods have been fully exposed several times.

Source recommendation that avoids nonsense and editorial filters and only posts the most authoritative updates in a well-organized format:

Martin Langeveld said...

Useful analysis of whether the spent-fuel pools at No. 1 may have been compromised:

Meredith Angwin said...


At first, I thought you were linking to IEEE, which is a pretty credible place. I don't find the IEER, "carbon-free and nuclear-free" to be credible. Been too long a supporter of renewables to enjoy seeing them oversold that way.

However, I will try to get around to reading it. So much stuff coming out, I don't feel I have time for organizations that are not believable to start with. It's a triage type thing.