Not moderator rods. Control rods. It's an important technical difference. Control rods are neutron absorbers to end the fission reaction. They were fully inserted into the core within moments of the earthquake ("reactor scram") and have remained there.

One of the things that's driving me crazy about the reports is that "radiation" comes in different flavors. Knowing what flavor radiation has spiked would explain more about what is happening. Instead we just get breathless reports about more badness happening. Some radiation would indicate containment breach. Other radiation would indicate uncontrolled fission. So which is it? Can't tell from the reports reaching/being issued by the press.

I feel as if I should just change channels for 5 years until a real accident analysis by real nuclear engineers has been published with lessons learned.

At least Charlie Sheen has disappeared from the headlines.....

unimog - I agree. My language was loose and I meant to say control rods. It's not clear that they are fully effective, and it seems as though there is still some percentage of operating power being developed by these reactors. So perhaps the control rods were damaged, or did not insert properly because the fuel rods were damaged?

And this comment in the news says it quite neatly ...

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Given the reported radiation levels, John Price, an Australian-based nuclear safety expert, said he saw few health risks for the general public so far. He was concerned for the workers, who he said were almost certainly working in full body suits and breathing through respirators. The workers at the forefront of the fight — a core team of about 180 — had been regularly rotated in and out of the danger zone to minimize their radiation exposure.

Price said he was surprised by how little information the Japanese were sharing.

"We don't know even the fundamentals of what's happening, what's wrong, what isn't working. We're all guessing," he said. "I would have thought they would put on a panel of experts every two hours."
----------------

MY THOUGHTS: The surroundings of the reactor are too complex for a robot to operate, and I don't think that a military standoff weapon will solve the problem here. So the final solution seems to come down to someone volunteering to go in there to add coolant and try to seal off the radiation leakage. This could well involve loss of life for some of the power plant workers i.e. it is essentially a suicide mission. As I recall from Chernobyl, there was a very brave helicopter pilot who flew over that reactor and lowered a concrete plug - in order to seal it. He died within a few days from radiation poisoning. I wonder if we've got the same final outcome here??

other Pete

Since they are admitting that significant percentages of the fuel rods at at least two reactors have melted and are presumably pooling at the bottom of the cores, I was wondering what happens to the material from the control rods or the boric acid. Would they mix in with the molten fuel and continue to suppress fission, or would they tend to separate out and not be so effective?

Is boric acid stable under the heat generated once the rods are uncovered? If so, you would think that the neutron dampening capacity would be increasing as they pumped in more and more sea water mixed with boric acid.

I was also reading that they are running out of boric acid. South Korean is sending a ship with more.

Under considerations for exposure control the workers would be being rotated in and then removed when their dose limit has been reached. Then they are no longer available to be exposed. Other workers would have to be found (and trained and briefed and sent up to the job). You can only send them back in if they can recover. Recovery from exertion or heat is pretty quick. Recovery from radiation exposure.... longer time if trying to maintain worker health and stay within regulatory guidelines.

If there are tasks that must be performed by specifically skilled people who aren't available or have already reached their exposure limit then the existing people who can do those tasks may wind up with radiation poising or dead because the guidelines no longer apply (This is war against catastrophe). Realistically this is probably the case. I'm sure there are heroic stories from this disaster that we don't know yet.

This is a really good question. I don't know the answer. If the boron is getting boiled out with seawater it definitely needs to be replaced. If it's just getting plated out as sediment replacing it might not be so important. But it's still a really good idea to keep injecting it.

I'm not at all surprised by the lack of information flow and there is nothing nefarious or suspicious about it. The guys and gals working on this are mostly highly technical types - i.e. stereotypically nerds/geeks - working in a very stressful environment. They are very very aware of how critical things are and are wearing themselves out trying to pick out the best choices from a series of bad answers.

Even if some of them were good at communicating to non-technical people before this, they are not going to "waste" the time/effort required for this non-critical task when they could be working on resolving the problem (or sleeping). I work with a large group of engineers in a safety critical field (not nuclear power) and the thought of taking them out of a high stress situation and dropping them into a press conference every couple of hours only brings really bad images to mind (as in english major vs engineer discussion of higher level math ).

The concept of a panel is straight out of how NASA handles things and yes NASA hires, plans and trains for that expectation to the point that the talking heads (i.e. the panel) usually aren't actually working the problem just translating techno speak into something approaching everyday language. To layer that expectation on other high tech tasks, especially during a "crisis" is unrealistic, though I would love additional real data just like everyone else.

- Eric

It would appear that the authorities are now scrapping the bottom of the barrel for solutions to control the situation (if they were ever in control), much like the Chernobyl response. The differences at the Fukushima installation are of course much more dire than even for the Chernobyl accident.

i) There are six reactors at the Fukushima installation all with on site storage of spent hot fuel rods. The Fukushima Reactor No 4 boiled dry spent fuel pond fire has completely destroyed the reactor containment building exposing the environment to these radionuclide fission products.

ii) It would appear that all six reactors have on site spent fuel reactor ponds.

iii) I suspect that the explosion in reactor number 3 which completely destroyed the environmental containment building along with most of reactor building, was subject to a Plutonium fizzle (yellow flash) within the reactor (reported Neutron radiation was reported prior to the explosion) rather than a hydrogen explosion, which sent the stored reactor spent fuel storage pond 1500 feet into the air.

iv) Using water cannon as a method of cooling down the reactors and storage ponds is a desperate last measure.

v) A Greenpeace Nuclear consultant stated last night on the BBC has stated that about 1800 metric tonnes of reactor fuel and hot spent fuel is on site at Fukushima distributed among the 6 reactors although he did say that only a few percent of this amount will most likely become airborne aerosols, much as the case in Chernobyl.

http://www.reuters.com/article/2011/03/15/japan-quake-russia-nuclear-idUSLDE72E1TJ20110315

http://www.reuters.com/article/2011/03/15/uk-japan-nuclear-chernobyl-idUSTRE72E69P20110315

They may have to change the Nuclear Accident scale and expand it to an 8.

Here is a good news article that discusses radiation levels at the Japanese plant, and how they compare to safe levels.

http://thechart.blogs.cnn.com/2011/03/15/what-you-should-know-about-radiation/?hpt=Sbin

I suspect that at this stage the power plant operator is trying to maintain safe radiation dosage levels for its employees. But I still wonder if political pressure in Japan will build up to the level where some employees are asked to sacrfice their own safety to solve this reactor problem.

When is a nuclear problem a real "catastrophe", and when is it just a "political and corporate catastrophe"?

other Pete

Has anyone read about the availability of grid power at Fukushima? That was first thing that was knocked out, when the quake struck, but I haven't heard a thing about that since then.

Maybe I'm just a happy ending kind of guy but what if grid power was suddenly restored, and that allowed the operators to start up some systems that have been idle all this time and save the day? Any shred of possibility in that?

Of course, there does seem to be various instances of physical damage, too, so restarting the normal cooling systems is not necessarily the silver bullet that it might seem to be. But anyway, just wondering about the grid power.

Edit:
I just ran across this article and it seems that maybe I wasn't that far off in my earlier conjecture. They are going to restore grid power to Fukushima soon, it sounds like.

Yet another conflicting story. The NRC chairman says things are much worse than are being reported. From the NYTimes.