Japan Earthquake: nuclear plants

Borek

What about one disintegration per 300000 seconds per mL?

causeceleb

then you are saying that TEPCO is saying that there is next to zero radioactivity (these
three isotopes) at the main gate?

clancy688

It is my understanding that such measurements are taken over a larger area than 1 cm³ and over a bigger timeframe than one second.

So for example you take 1 m³ air and count all disintegrations over a period of twelve hours. Afterwards you recalculate those results into easier to understand numbers, e.g. Bq/cm3.

What you finally get is more or less a disintegration probability. The probability that there'll be a disintegration in one cm³ air is 0.0003% every second.

Borek

No, I am just explaining what the result means.

clancy688

Big thanks! The graph is interesting indeed.

There was a MAJOR C137 release going on for at least one day between March 30th and 31st. 100 TBq/h, makes 2400 TBq C137. Converted value: 96.000 TBq, over 10% of the total number. That alone would be sufficient for an INES 7 classification. What happened that day?

Or is this a mistake on my part, did I read the chart wrong?

In case it's real: Then screw my previous comments about airborne releases and the number not rising anymore - in that case, those are wrong of course.

causeceleb

well, i thought 9.5E-06 meant 9.5 times 10 to the minus 6, but
the whole thing just threw me for a loop.
thank you for helping me grab hold of reality :)

SteveElbows

Photos are interesting. Im pretty sure that some of the stuff seen is an off-white colour because earlier in June they sprayed the anti-scatter substance onto the roof of reactor 4. This could also be what the gunk around one of the photographed valves is, although I cannot be sure.

Good to see the gate between the fuel pool and the reactor well, good to see the reactor well full of water. I wonder if the water level will stay stable.

Do you care much now about the reported skimmer surge levels? To add to list of possibilities regarding what has changed, I suppose it is possible that gate between fuel pool & reactor well still had a leak, and now they have filled up the reactor well, water is not being lost from fuel pool so quickly, so less filling required? Anyway it seems that I was probably wrong to suggest that maybe they use the new water system on a more continuous basis, since I checked recent status reports and brief injections via this system have been reported in recent days.

Another possibility is that since completion of steel structural support under fuel pool, they feel they have more options available to them, perhaps they were avoiding certain things because of fear of structural failure. For example I dont think they started filling the reactor well & storage pit with water until the first phase of structural support work was done, but this could be a mere co-incidence of timing for all I know.

Bodge

The CTBTO monitoring is back.

I find the I-131 peaks to be indicative of ongoing fission somewhere on the site.

SteveElbows

I dont think you are reading the chart wrong,but due to a lack of official narrative about air release events past the first week, I cannot really tell you what happened on that day, but I do intend to look into it further again sometime. It was the even higher magnitude release estimated for a time on March 15th that got most of my attention when I first found this document.

As for the number not rising significantly anymore, using computer translation of that NSC document Im fairly sure their estimated total releases covers the entire period shown in that graph, so their figure of 630,000 TBq covers the includes the end of March figure you mention. Actually this document also shows that they slightly revised upwards their calculation for total release of Caesium. Using INES conversion I think the new NSC-calculated total release for period up to 6th April was 670,000 TBq. Crucially I dont think any high magnitude releases beyond the dates covered by this report have been mentioned, so I believe your point that later daily releases dont make very much difference to the estimated total is still valid.

SteveElbows

I believe we still need to check for other factors which could cause spikes in such data. For example weather.

clancy688

Well, there's a problem. On page 4 there's another chart showing exact values and time periods. I used it to calculate the whole C137 release (no time for I131, maybe tomorrow). Released Cesium (per hour) is (Release Rate / (1 + I/C Ratio)).
But I'm coming 2000 TBq short. NSC's estimate was a release of 12.000 TBq C137. I only get 10.000 using their numbers.
Oh, and the exact C137 release for March 30th-31st would be 1900 TBq (unconverted) or 75.000 TBq (converted).

Bioengineer01

Did you guys look at the way the releases acknowledged by TEPCO in the document you mentioned are reflected in the CTBTO charts, posted before? Is it reasonable to back extrapolate from that and take a rough guess at newer non-reported releases at later dates from the peaks in the graphs? Am I making sense?

LabratSR

I haven't seen this posted yet, sorry if it has been.

English Version of Timeline Released.

http://www.tepco.co.jp/en/press/corp.../110618e15.pdf

tsutsuji

http://mainichi.jp/select/jiken/news...40075000c.html the reason of the trouble was a mistake in the control of the water level in a tank. Although the water level must be set at 3% above the bottom when the facility is stopped and 30% when it is running, the facility had been started with the level still set at 3%.

http://www.nikkei.com/news/headline/...E39790E0E2E2E2 : from 1 July to 4 July, Tepco will be installing a new water tank whose purpose is to centralise the two water routes (the route from the filtrate tank, and the route from the water purification facility) that take water to the reactors. The new tank will have a 1000 ton capacity. On 1 July the cooling is switched back to the filtrate water tank. The new "buffer tank" is shown on the diagram at http://www.tepco.co.jp/nu/fukushima-...10701_02-j.pdf . At the same time, the PVC hoses will be changed to steel pipes.

MiceAndMen

Hallelujah we finally have an official TEPCO diagram for the refueling floor at unit 4. Very interesting pictures. How very strange to see the reactor well open to the sun and sky looking like a large swimming pool.

joewein

I find they show the exact opposite.

If fresh I-131 was produced by fission and released then one would expect levels to come back to the same levels in the first chart after every fission event, more or less. The fact that both the valleys and peaks of the iodine curves drift down in line with logarithmic decay indicates that no fresh I-131 is being produced. The ups and downs are probably mostly driven by weather conditions, such as changes in wind directions, rain, etc.

The second argument against ongoing fission is that the ratio of iodine to cesium is shifting just the way one would expect from decay. Cesium has been holding almost steady (with some random ups and downs) since later March, while iodine keeps falling (also with some ups and downs). That's precisely what one would expect in the absence of ongoing fission, given the different half lives (Cs-134: 2 y; Cs-137: 30 y; I-131: 8 d). If there were fresh releases from ongoing fission, the cesium and iodine curves would look a lot more alike than they do.

joewein

I am attaching horizontal views of Fukushima 1 unit 1, looking north and looking west. Units 2-5 are somewhat different, but it should still be a useful reference.

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