Saturday, March 26, 2011

Slowly leaking

And I don't just mean the power plant itself.

It's been interesting to follow the news management of this ongoing event, and particularly the slow dripping of information coming from TEPCO. I've blogged several times about how I don't think the risk is currently that serious for me, but that shouldn't be interpreted as any sort of approval of how TEPCO have handled things. They are clearly a fairly incompetent and dishonest outfit, with a history of maintenance failures and cover-ups, shielded from any genuine oversight by their cosy relationship with the government and the pusillanimous nature of the local media. There's plenty of evidence of their failures, eg here, here, here. Incidentally, and not at all coincidentally, TEPCO was also at the centre of the recent "amakudari" kerfuffle. I can imagine how the departmental "oversight" goes: "So, what is the current status of your maintenance program, TEPCO technical director?" "Oh, it's fine, Director-General Ishida-san. But enough about that, let's sort out the salary for your non-executive directorship position next year." It is telling that the Govt has basically been completely reliant on TEPCO for all information about the crisis, and it's been reported that PM Kan has basically had to resort to yelling at TEPCO executives to get some information out of them.

As I mentioned a couple of days ago, all the evidence has for some time pointed towards a significant leak from a reactor core. The radiation levels around the plant don't seem to be dropping much if at all - it can't be expect to actually decay much over a few days, but should surely start to disperse if the source is eliminated. There was a brief mention of neutrons being found some way off-site, which I think suggests ongoing and unshielded fission, long after the reactors were supposedly shut down. Remarkably, this news was only released 10 days after the observations were actually made, and it was only at that point that TEPCO said they would start to look for uranium and plutonium! And it is only now, following the unavoidable evidence of the recent radiation burns suffered from workers on site (who weren't even wearing boots despite wading through water!) and heavy contamination of the sea, that the likelihood of a leak is being openly discussed by officials (also here and here).

The accident looks like being upgraded to a level 6, though I don't think this is official yet. There is a de facto increase in the official 20km exclusion zone to 30km, as it seems that no-one will make deliveries in that area and there's not much point in living there when you have to stay indoors all day and the Govt is openly admitting that "the present conditions are projected to continue over a long period of time". Some modelling suggests that infants may have received as much as 100mSv so far, even outside of the 30km advisory zone. It's obviously a horrible disaster for the area.

14 comments:

Hank Roberts said...

When people start doing environmental sampling, they often find prior dumps and leaks that nobody knew about, left by people who never expected the problems to be caught.

Jesús R. said...

"Some modelling suggests that infants may have received as much as 100mSv so far, even outside of the 30km advisory zone."

"On March 25, Japanese authorities reported to the IAEA that they had recorded the radiation doses to the thyroids of 66 children living just outside the perimeter of the evacuation zone. These measurements are important because the thyroid tends to accumulate iodine, and radioactive isotopes of iodine make up much of the radiation field being measured far from the reactor site. In addition, children are especially sensitive. The measurements showed no significant deviations from background radiation levels in these children, 14 of whom were infants."

http://mitnse.com/2011/03/26/304/

Dallas said...

Still a lot of confusion. For what it is worth the IAEA report had this, "The highest value was observed in the prefecture of Ibaraki, where on 25 March a deposition of 480 becquerel per square metre for iodine-131 was observed; the highest value for caesium 137 was measured in Yamagata at 150 becquerel per square metre." It is confusing what normal back ground levels of C137 really are, but 100 becquerel seems about average. I have seen any reports of other isotopes which should be a good thing.

Steve Bloom said...

Regular readers may recall that a little while back on this blog I was wondering about neutron readings even while being painted by some as a survivalist. See how I maintain focus under the most adverse of circumstances!

The neutron thing is very worrying, especially as a samll amount of fissioning can lead to more fissioning as more stuff melts. The linked news report is unilluminating to say the least, I assume because TEPCO and the government didn't care to discuss the details and implications. By utilizing several monitors and moving them around, by now they ought to have a pretty good idea as to the source and trend, and yet they say nothing. I need to learn to be more cynical.

I'm assuming it's not just rod material dispersed into the air and water, as that would be much less serious than criticality and so something they would want to announce. OTOH I suppose TEPCO may believe that there's just no good way to tell the public "It's really bad, but everyone be happy that it could be worse" (well yes, Nuclear Reactor Boy died, but his diaper is still partially on!) and so continues to be as unforthcoming as the government will allow them to be. If it is just the rods, let's hope it's not the MOX.

Hank, neutrons aren't that sort of thing. There's a tiny background level to be expected near large amounts of fissionables, but the only thing that's clear from the report is that things have gone beyond that. It helps to know that free neutrons decay quite quickly (mean lifetime ~15 minutes), so detecting them at all means there's an active process underway.

David B. Benson said...

Dallas --- Caesium 137 does not occur naturally.

dhogaza said...

And iodine-131 has a half-life of 8 days ...

Dallas, cesium-137 and iodine-131 are coming from the reactor, there's no chance for confusion with "background radiation".

Indeed, that's why the Japanese government and TEPCO are suddenly acting scared over the last couple of days ...

Hank:

"hen people start doing environmental sampling, they often find prior dumps and leaks that nobody knew about, left by people who never expected the problems to be caught."

Well, I doubt there were prior dumps and leaks at Reactor 3 that would give someone walking barefoot in the puddles that aren't supposed to be there a 2 sievert dose (with 4 sieverts delivered body-wide being LD50).

And it would be an interesting coincidence if the seawater monitoring offshore of fukushima that's yielding interesting numbers were due to a past dump or spill ... there's only one place it would've come from, and violating the law in the past wouldn't exactly put TEPCO in a shining light of innocence ...

Dallas said...

http://www.vinography.com/archives/2005/06/how_much_cesium_would_you_like.html

David, true, but there is a small background due to weapons tests, Chernobyl etc. A good reason to drink beer.

Steve Bloom said...

First two paragraphs of the current top story at the beeb:

"Radioactivity in water at reactor 2 at the quake-damaged Fukushima nuclear plant has reached 10 million times the usual level, company officials say.

"Workers trying to cool the reactor core to avoid a meltdown have been evacuated."

Dallas said...

dhogaza,

Iodine I agree, short half life. Cs 137 though is weird. (INDONESIA)
The use of the Cs-137 technique for measuring soil erosion/sedimentation at a small catcment Ciliwung, Tugu-Bogor

That study found a Cs 137 background averaging in the 200 Bq/M^2 range. I would assume the IAEA measurements are in excess of the normal Cs 137 for the area. Don't know for sure.

Some other "estimates" reported have Cs 137 at 8MBq/m^2 which is nearly twice Chernobyl. Kinda hard to figure out who to believe.

The press release Steve referenced, "10,000,000 time normal" relates the contaminated water (1 Sv) being pumped out of the reactor building to normal background radiation of 0.1 MicroSv. Seems to me that contaminated water from a leaking reactor following a partial melt down might be considerably higher in radiation than drinking water.

The leaking reactor is a big problem, but 10,000,000 times more radioactive than drinking water is not very helpful in figuring out how much of a problem. Great for selling newspapers though.

Cs 137 is also unique in soil because of its melting point of 83.3 F. The concentrations measured now will reduce significantly in the late summer if it melts (which I assume is possible) and mixes into the soil, cultivated land has about half the concentration of pasture land (Australian erosion study) for example.

Sedimentation following rainfall can create hot spots which may have been what was measured. The average of the readings was much lower than the high readings. A lot of factors have to be considered to determine long term impact and mitigation.

crf said...

TEPCO retracted its report that radiation 10 million times higher than expected was found in some pools of spilled water in the plant's basement.

...

There is still very little information on contamination outside the immediate reactor site. I guess it is not actually important, from a public safety standpoint, to get that info immediately.

But I wonder how they would do it, and if they are?

Steve Bloom said...

crf, by now they have lots of real-time data. They could even put it on-line.

Another feature of nuclear technology, the technology so wonderful that even after we've had a disaster we can behave as much as possible as if we haven't. *sigh*

yea-mon said...

the highest value for caesium 137 was measured in Yamagata at 150 becquerel per square metre.

I've got to wonder how that got up here - the prevailing winds are out to the coast of Fukushima this time of year.

James Annan said...

Yeah, I was wondering about that...but there have been quite variable winds over the last couple of weeks and some of Ignacio's plume plots showed transport to the NW.

skanky said...

This may only be indirectly relevant rather than directly to the current problems, but it might be interesting, nonetheless:

http://www.bbc.co.uk/blogs/adamcurtis/2011/03/a_is_for_atom.html