zapperzero said:
plume's laid down to the northwest if I'm reading the map right
would be interesting to correlate with weather at the time of the accident, iirc most of the time the wind was blowing east or south east, out to sea? but then my memory is very bad.
Well as radiation survey maps from previous years showed the same pattern, this stuff has been discussed before.
I don't have the most detailed studies to hand, but here is a rough description of relevant info:
Wind direction was out to sea at several stages, including the explosion of reactor 3 building. Thats probably what you are remembering. It often came up when issues such as whether reactor 2 was really responsible for most environmental contamination came up. For example there were people who attached much significance to the reactor 3 explosion, and it was not possible to prove to their satisfaction that it was a minor event in terms of radioactive releases to the environment compared to reactor 2, because the wind direction at the time prevented a strong record of the event showing up in land contamination readings.
The bulk of land contamination is usually put down to events of March 15th 2011, due to a combination of the vigorous emissions seen leaving the reactor 2 building, and the wind & other weather factors. Initially the wind was blowing approximately south, but during the period it gradually moved further clockwise, so that at some later point there was a plume to the north-west. Some of this hit a band of rain in the area (or according to some reports, snow) which greatly enhanced land contamination to the north-west.
There could have been some land contamination to the north from the reactor 1 vent and/or explosion, but again this tended to be overshadowed by the much higher levels of contamination on the 15th.
The rather poor state of narratives and accurate emission details for the period later in the month mean that further possible significant emissions, including from reactor 3, are not well described. There has been some attention to emissions around the 20th-21st March, because the wind was again blowing south and causing some radiation to show up in locations well south of Fukushima, such as Tokyo. Again I believe rain may have been involved in some places, and this episode was also of interest due to recurring 'white or black' smoke events at reactor 3, and indeed the general problems they had achieving anything resembling stable temperatures in March, well after the first few days of meltdowns.
The failure of company & government officials to swiftly admit and discuss containment failures at the reactors hampered the ability to generate a useful mainstream narrative that could be combined with weather and radioactive contamination data at various points to build a detailed picture in terms of the radioactive ground contamination and what reactor events it related to. Even when we could see for ourselves in photos and video steam/smoke escaping from reactor 3, and when much later there were photos published showing the vigorous nature of the emissions from reactor 2 on the morning of March 15th, attention still tended to linger on explosions, fuel pools and venting. So the weather on March 15th didn't get as much attention as it deserved, although it is featured in several reports which include rain radar images from pertinent moments. If I find them I will post a link.
edit - I'm not sure these are all the weather-related reports I've seen in the past but between them they describe fairly well the weather-contamination events and attempts at analysis.
http://www.nsr.go.jp/archive/nisa/shingikai/700/14/240723/AM-3-2.pdf Pages 14-16.
http://www.vic.jp/fukushima/global/global-e.html
http://www.irsn.fr/FR/Larecherche/p...Abstract_intervention_Anne-Mathieu_TS12a1.pdf