Fukushima: Texas A&M forecasts, other simulations.

The Texas A&M forecasts are in:

Monday, April 4
• 2011-04-04 12Z - forecast only
• 2011-04-04 06Z - forecast only
• 2011-04-04 00Z - forecast only

I also found some readings from KEK in Tokyo, that are similar but more frequently updated than the SPEED! measurements. They are here and here. As shown earlier, these measurements show several spikes stemming from the releases from the reactors and a larger set of bump starting around March 21st that seem to correlate with the pool cooling events. As soon as the pools are filled, i.e. cooled, the sources terms stops immediately.

At the start of the accidents, there was not much data with regards to the source term at Fukushima, i.e how much elements were escaping from the reactors. Most of the computations performed by different groups were focused on  a worst case scenario of continuous release, which was never supported by any of the SPEED! measurements. The simulations include:

• Special Forecast products for Fukushima produced by NILU-ATMOS (disclaimer: These products are highly uncertain based on limited information for the source terms. Please use with caution and understand that the values are likely to change once we obtain more information on the overall nature of the accident. The products should be considered informational and only indicate 'worst case scenario' releases. From what we've learned recently, it seems releases of this magnitude have not yet occurred. Furthermore, these modeling products are based on global meteorological data, which are too coarse to provide reliable details of the transport of the plume across Japan.)
• Eurad simulations. (Fukushima site) Disclaimer: This simulation is a so called "worst case scenario" with continuous release rate. The value of 0001 Bq / m 3 correspond to appr. one millionth of the concentration at the source. At distances more than appr. 2000 km away from the source, the concentrations are not harmful to health. The simulation starts at fictitious 15.03. 00 UTC and will continue to run in order to Demonstrate the InterContinental. Relaese exact transport When rates are published we will restart the simulation with reliable values.

When given more data from the CTBTO, the german Eurad model was re-run and the dispersion model was compared as to when CTBTO stations would detect the plume from the Fukushima plant. The animated gif is here.

and seems to show a pretty good fit with regards to when the stations would detect elements given the new simulations. Finally, an NOAA HYSPLIT model is currently being run by somebody which seems to give similar result with regards to particle trajectories. It is here. 

Fukushima: Combining information from UC Berkeley, Texas A&M and TEPCO.

There is a new report from UC Berkeley that provides a timeline of the radiation measurements. The report is here:

Of interest today is the peak observed on March 24th (California time = GMT - 9). If one checks the Texas A&M maps, it looks like there is a possibility to connect this peak to a source term around March 20th at around midnight (GMT) or a little bit before.

The TEPCO press release for that time frame show something new that day among other things:

Cooling of spent fuel pools At approximately 8:21 am, March 20th, water discharge to Unit 4 by fire engine has started with the cooperation of Self-Defense Forces.

Or because the graph shows counting performed for the whole day in California (as opposed to actual time period) another later event:

Cooling of Spent Fuel  From 3: 05 PM to 5: 20 PM on March 20th, 40 tons of seawater was injected into Unit 2 by TEPCO employees.

The finding seems consistent with any of two source terms occurring at 

• 8:31 AM on March 20th, or about midnight March 20th (GMT) and,
•  3:05PM/5:20PM on March 20th or about (6:00AM GMT March 20th).

 The detection in California has occurred around March 24th (PST) or about March 24th/March 25th (GMT).

Hence it becomes difficult to delineate which of the two source terms was effectively detected at Berkeley. Now let us watch the Tokyo measurements. it shows a start at about 8:00 am March 21st (JST)

which seems consistent with reactor #4 pool cooldown. The second peak seems connected to the reactor #2 cooldown but it could also be connected to the smoke observed on top of unit 3 (March 21), however that would seem unlikely since according to TEPCO environmental readings remained at the same level when the fumes occurred. Once the cooldown is obtained and stable, there is no expectation of further release to the environment. The expectation is now that the radiation measurements should continue decreasing (irrespective of whether the winds are westerly).

Fukushima: Texas A&M Forecasts for April 1, A note on the Ibakari Analysis of March21st.

The Texas A&M forecasts are in:

Friday, April 1
• 2011-04-01 12Z - forecast only
• 2011-04-01 06Z - forecast only
• 2011-04-01 00Z - forecast only
Dates and times are shown in international format:  YYYY-MM-DD HHZ.  The Z indicates that the hours are given in Coordinated Universal Time (UTC or Greenwich time).
Japan is 9 hours ahead of UTC.  (00Z is 9:00 a.m. in Japan.)

In the Ibakari Analysis for the March 21st sudden dose rate increase, David, a commenter, pointed out the following:

That spike has been attributed to "rain" in sources that I've seen, for example in Daniel Garcia's graph here: http://twitpic.com/4f0qfr

The graph no longer exists but it showed the dose rate increase with a mention of "rain" next to it. I responded with:

Thanks for the comment and info. Rain is just the final means by which the radioactive components eventually are deposited in some area ( on some sensors). What is important to understand is how this is transported. In this entry, I am trying to figure out what is the possible source term at the plant that could have triggered this increase in the dose rate. With the help of the Texas A&M computations showing the delayed transport between the plant and some other area, it looks plausible to have this event be the cooling of the spent fuel pool of reactor 2 being the culprit. The cooling must have produced evaporation that eventually fed into the plume. The Texas A&M computation seem to suggest that there is a good fit between the time this event happened and the time is was detected several hours later in Ibakari. If you have any other source of information, I would love to hear about them.

Thanks David. I can see also the point that dose rate increase only when it rains because somehow the radiation is diffused all around as opposed to following specific trajectories such as the ones the Texas A&M team is computing.. However, while rain occurred in that area on March 21st ( http://weatherspark.com/#!graphs;ws=33162 ), there has been other rain events since with no corresponding large dose rate increase.

As can be seen from the SPEED! and other prefecture measurements graph at http://fleep.com/earthquake/ .Here is the Ibakari graph:

In other words, the insertion of sea water in the spent fuel pool of reactor 4 on March 21st, seems consistent with the dose rate increase in Ibakari several hours later (please note that I am not saying it is the only reason, just that it seems consistent based on the incomplete data we have so far). In particular, the trajectory computations show the possibility of the particles born from the cooling of the fuel rods to be over Ibakari in the right time frame. The rain is probably a compounding element that enabled the 4 microSv/hr dose rate increase as detected by the prefecture measurements. 

Dr. Matthias Braun from Areva produced a presentation, available from Energy from Thorium, that provides a background to folks who do not know nuclear systems, All the information in that presentation stem from data gathered from different sources accessible over the internet. Of interest are the following two slides. The first one is a timeline that stops just before March 21st and the second shows how different the accident in the pool  at reactor #4 is with regards to radiological release from similar release from reactor 1 through 3. As stated in the presentation, we do not know if these releases have occurred already.Let us note that the presentation talks about pool #4 whereas the dose rate increase seems consistent with water thrown in pool #2.

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