Wind maps for 17th 18th and 20th Feb 2017 Oslo and missing data points from EURDEP in Sweden, Norway and one reading from Denmark showing the radiation was OK on the 20th .
Winds did come from the north at times and also from the southeast as well during these dates, early If a release was done in the early hours/morning of the 17th Feb 2017, the plume would have moved into Sweden and then later been sent west.
The data on the Denmark monitor was largely missing but did actually have the 20th Feb 2017 data showing normal radiation levels
I added some radiation monitoring data from the east coast of Norway and heading north (including one monitor in the mountains) from there to show that a lesser plume made this distance but the data removed was for a shorter time frame. The wind maps show that the direction of the wind did also, at times, head east to account for this Plume.
I also checked the Finnish monitoring system but the data was generally intact but for a small brief rise on one east coast of Finland monitor showing the plume was likely dissipated or broken up over the Baltic sea.
Data compiled by Shaun McGee
Historical wind chart data from Norway; https://www.yr.no/place/Norway/Oslo/Oslo/Oslo/almanakk.html?dato=2017-02-20
Radiation Mapping data from; http://eurdepweb.jrc.ec.europa.eu/EurdepMap/Default.aspx
Note; The Halden reactor monitor for October 2016 (the original release) was for only a few hours and the data is missing to show that. Over a few months some small rises and missing data points are evident but the largest period of missing data in February 2017 is the same as the Oslo data maps below, over a few days.