Level of iodine-131 in seawater off chartContamination 1,250 times above maximum limit

The Japan Times ^ | March 26, 2011 | KANAKO TAKAHARA and KAZUAKI NAGATA

[SteveH]

The level of radioactive iodine detected in seawater near the Fukushima No. 1 nuclear power plant was 1,250 times above the maximum level allowable, the Nuclear and Industrial Safety Agency said Saturday, in a development that indicates contamination from the ruined reactors is spreading.

Tokyo Electric Power Co. meanwhile admitted it neglected to alert workers when it detected high radiation in a reactor building nine days ago.

The iodine-131 in the seawater was detected at 8:30 a.m. Friday, about 330 meters south of the plant's drain outlets. Previously, the highest amount recorded was about 100 times above the permitted level.

[RummyChick]

So let’s say they are telling the truth and it is only 100,000 times the level it should be.

Since Iodine 134 has such a short half life - how is it getting so high
This is Reactor 2.

[chimera]

I'd like to see the data on when the sample was taken and when the gamma radioassay was performed. 134I is part of a decay chain from another fission product, 134Te. So you have two possible mechanisms for 134I production: that produced by fission, and ingrowth from the decay of 134Te. Now, they are both relatively short-lived forms, so even with the ingrowth process, you have to have knowledge of sampling and assay time to make sense of the numbers. But if you had a lot of 134Te produced initially, along with the 134I directly, and for some reason transported to the sampling location by some release pathway (both are fairly mobile in the environment), the fission production+ingrowth could account for the lingering 134I they are seeing.

If you plot the solutions to the equations that describe the process of decay and ingrowth, depending on the relative half-lives, you can see a peak in the concentration of the daughter product at some point after the initial production of the materials. The time that peak appears depends on the relative half-lives. I haven't done it for these forms, so I don't know when the concentration of the intermediate product will peak. But since it is a decay chain, you have to account for that.

[RummyChick]

Now to add some more confusion:

http://www.physicsforums.com/showthread.php?p=3213027

here is the NHK report
TEPCO retracts radioactivity test result

Tokyo Electric Power Company has retracted its announcement that 10 million times the normal density of radioactive materials had been detected in water at the Number 2 reactor of the Fukushima Daiichi nuclear plant.

The utility says it will conduct another test of the leaked water at the reactor’s turbine building.

The company said on Sunday evening that the data for iodine-134 announced earlier in the day was actually for another substance that has a longer half-life.

The plant operator said earlier on Sunday that 2.9 billion becquerels per cubic centimeter had been detected in the leaked water.

It said although the initial figure was wrong, the water still has a high level of radioactivity of 1,000 millisieverts per hour.”

Here is an interesting comment

“Assuming that Tepco uses detectors with better than amateur resolution, there is no way of mistaking the gamma spectrum of I-134 for something else.

They should publish the spectrum. “

And another:

“Why are they retracting the data in such a public way.
a) Is it because of high dosage 2.9 x 10^9 , or
b) Because of the short 1/2-life of 53 minutes and thus should not be present 16 or 17 days later

if b) then how will they explain Tc-99p 6hr 1/2-life, that should also not be present “

[chimera]

The gamma spectral analysis software that I use will generally flag a possible conflict in energy identification, but if you apply other factors, like gamma abundance, half-life, and detector efficiency-normalized intensity ratios, it can do a good job of sorting those out. If they mis-identified the nuclide because of carelessness in setting up or interpreting the gamma analysis, I will be the first to stand up and chide them. A good radiochemist will be careful to check things like this.

Yes, they should show the gamma spectrum. Then we can take a look at it and see if there are energy ID conflicts.

[RummyChick]

TEPCO president fell sick amid troubles at its nuke plant

Shimizu has not appeared in public since attending a press conference on March 13, two days after the catastrophe that wreaked havoc on northeastern and eastern Japan.

http://english.kyodonews.jp/news/2011/03/81347.html

Sounds like something Obama would do.

Well not really.

He would just go play golf.

[RummyChick]

here is their explanation

Tepco said it miscalculated the radioactivity measurement in the unit 2 turbine building because it mistook the data for iodine-134 for the data of cobalt-56, which has a longer half-life

http://www.washingtonpost.com/world/radiation-levels-reach-new-highs-as-conditions-worsen-for-workers/2011/03/27/AFsMLFiB_story.html

[RummyChick]

:Meanwhile, Tokyo Electric, known as TEPCO, is studying whether highly toxic plutonium is contained in the soil of the plant. The No. 3 reactor was using plutonium-uranium mixed oxide fuel for so-called ‘’pluthermal’’ power generation.””

http://english.kyodonews.jp/news/2011/03/81357.html

[chimera]

Okay, I see what happened. 134I has a gamma at 848 KeV with a normalized intensity of 100 and 56Co has a gamma at 846.771 KeV with a normalized intensity of 100. So the difference, 1.23 KeV, is within the resolution of a typical HPGe detector. Okay, now I see what happened.

So now the question becomes, what is the source of that 56Co? It's fission yield is very, very low, so it probably isn't fission. It is neutron-poor, so it probably isn't neutron capture (activation). It is usually a proton-induced reaction. Looking at the Chart of the Nuclides, the only thing that comes to mind is a very energetic photodisintegration reaction, where both a proton and a neutron are removed from a 58Ni nucleus. But I have never seen this in any irradiated nickel I have looked at.

[Palladin]

We heard the same kind of lies, miscalculations, confused results etc. after TMI. There was no credible info coming out from Met Ed, the electric compnay; or from the Nuclear Reg. Comm.; or from the PA. DER.

5 years later they determined that there had been a core meltdown.

What to believe? Whom to believe?

I’m just glad I don’t live in Japan. I would hate to have to go through all that again.

[SteveH]

the only thing that comes to mind is a very energetic photodisintegration reaction, where both a proton and a neutron are removed from a 58Ni nucleus.

photodisintegration is typically fusion induced (?). if so, would that not rule it out big time (?).

It is neutron-poor, so it probably isn't neutron capture (activation).

How about any steel (eg rebar) surrounding the 1F4 or 1F3 SFPs. 55Fe + fast n = 56co. Also 1F2 possible but that would require both a vessel and containment breach (which in my uneducated thinking would be rather unlikely, due to massive engineering fudge factors used in the design...)

I dug this up about a 1989 pump accident at 1F2, but it does not seem to be directly relevant to anything at this time (at least to me):

http://search.japantimes.co.jp/cgi-bin/nn19990325a8.html

[chimera]

The photon source for the photodisintegration can be the shutdown field of gamma after fission stops. That was what I had in mind.

Co is above Fe on the chart, so you need a mechanism for gaining a proton. That is typically proton bombardment. Beta emission is the preferred method for neutron-rich nuclei, but I don't see any of those below Co on the chart. 56Fe is stable. Ni is above Co so I looked at looked at the n-p pathway and that would mean 56Ni(n,p)56Co, but 56Ni is unstable and neutron-poor, so it is unlikely to be in a reactor environment. I looked at n-alpha but that would involve 59Cu, even more unlikely. I'm stumped at this point (probably missing something obvious).

[RummyChick]

I saw a post somewhere while surfing the net that said he felt his face burn after being in the rain. I think he was in California.

And sure enough, even in Massachusetts they are finding radiation in the rain.

Would California have had enough to feel it in the rain?

Who knows.

I have been reading the physics forum and even they are having trouble deciphering the latest numbers from TEPCO in terms of it all adding up to make sense.

[chimera]

I saw a post somewhere while surfing the net that said he felt his face burn after being in the rain. I think he was in California.

If someone was having that kind of symptom (erythema), they are probably absorbing skin dose in the range of 2 Sv. Other than those contractors who were walking in that one puddle, there have been no other reported doses in this range in Japan. In California, with a dilution factor in the range of hepa-billions, I doubt if we'd be seeing these kinds of symptoms.

[SteveH]

Co is above Fe on the chart, so you need a mechanism for gaining a proton.

Doh, maybe I should stop... ^_^

56Ni ->(electron capture) 56Co+

According to here:

http://en.wikipedia.org/wiki/Electron_capture

56Ni has a half-life of 6.1 days.

(warning: may not be much better than my other guess)

Anyway there must be a lot of junk byproducts hanging around the area if the measurements can (now) be believed. The question is how they were transported from where they should be contained. My guess would be the 1F3 and 1F4 SFPs, just because of what I would imagine to be the large engineering fudge factors built into the containments (but who knows...)

[chimera]

Well, that's a thought. So how could we produce the 56Ni? It could be...

58Ni(n,3n)56Ni...?

I have no idea of the cross-section for this reaction. I can't find any data in the cross-section tables. Which means its either very small or hasn't been studied. There are some references to neutrino-induced production in Type Ia supernovae and collisions of double-degenerate white dwarfs, but obviously that's not what we're dealing with here. Still, if there is some kind of reasonable cross-section for the n-3n reaction, who knows?

[SteveH]

Hmm, then maybe it’s just a questionable measurement, and if they take more measurements then the situation may clarify itself (hope).

[RummyChick]

Here is Joe's interview today
http://www.youtube.com/watch?v=z_mk7T5MQxI&feature=player_embedded

here is a cam

http://www.tepco.co.jp/nu/f1-np/camera/

[RummyChick]

the smoke or whatever that was in the photo that was around at 8:00:36 now seems to have disappeared

[mewykwistmas]

“With the terrible earthquake and resulting tsunami that have devastated Japan, the only good news is that anyone exposed to excess radiation from the nuclear power plants is now probably much less likely to get cancer.”

[RummyChick]

Corium or not corium?