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2015/03/05 at 3:09 pm
Southern Hemisphere February 2015 Background Radiation Report.

Station location


This short animation of Northern, and Southern Hemisphere air circulation, shows why we can get detections so far south.


February 2015 Background Summary

Pretty much the same as last month. We see a drop in the month average background level for February 2015, and the rain water test shows manly Beryllium Be-7, and Lead Pb-210. The traces Iodine I-129 and Uranium U-235 showing up in the previous years rain water tests, are now below the reliable detection levels of the equipment here.

The good news is that background levels here have stabilized, at least at this location in the Southern Hemisphere. I still detect the occasional event. These detection events are generally not as large, or as frequent as previous years.

February 2015 monthly average background radiation level was 30% above the pre-Fukushima average.
February average for 2014 was 40% above the pre-Fukushima average.
February average for 2013 was 39% above the pre-Fukushima average.
February average for 2012 was 37% above the pre-Fukushima average.

Technical details:

(Note: The 4yr average referred to in the charts, is the 4yr pre-Fukushima

What the coloured alert levels, in the bar charts indicate.


February 2015 (30% above month average)


February 2014 (40% above month average)


February 2013 (39% above month average)


February 2012 (37% above month average)


February 2015 Rain Water Test Report


February rainfall was 426.6mm.

Beryllium Be-7 can be made by spallation in the upper atmosphere, during solar events, and takes around two weeks to reach the surface. Lead Pb-210 is a decay daughter of Radon Rn-222. Both these isotopes can also be released from a
Nuclear accident.

Roof down pipe filter design for rain water testing.


Rain Filter Test Chart (The chart is minus background.)

In this chart I have CPS on the Y axis to show activity, and have turned off Y log to show linear scaling. This is only a test chart of the polyester part of the rain water filter system design. The Polyester filter actually captured more than the carbon filter.



Previous rain water and soil tests can be found here.


2015/02/22 at 8:17 pm
Do cyclones draw Fukushima radioactive air contamination through the equatorial barrier, into the Southern Hemisphere?

Caloundra (Queensland Australia) 22th February 2015 – The remnants of Tropical Cyclone Marcia came and went, the day average background here actually dropped then rose.


The dip in the day average occurred a day before the degraded Cyclone Marcia was closest to here. We had around 330 mm rain over a few days. This suggests whatever was in the air was being washed out.

Geiger counter testing of a car bonnet rain swab collected on the 20th, 630 cpm or ~1.0 uSv/hr. Not nearly as high as other rain event tests.

When placed in the scintillator there was very little Radon-222 present, again not nearly as high as previous rain swab tests. The rain swab is also not showing any significant Be-7 or Pb-210, as recent rain test have shown. Radon levels were low averaging around ~ 0.5 pCi/l over that period. As the tail of Cyclone Marcia left the area we had a wave of radiation pass through. Haven’t seen this type of radioactive cloud stand out event since late 2011, 2012, and 2013.

Here is the 24 hour chart.



(Caloundra is in Southern Queensland and Cairns is in Northern Queensland Australia.)

Report from a contact near Cairns in North Queensland, 20th February 2015

“I would like to report an unusual event yesterday. Yesterday 20. Feb 15 between 17:00 and 18:00 the alarm set at 0.400 uSv on my Gamma Scout kept sounding continuously. The daily average reading after midnight was 0.167 uSv, a value, that I have never had that high since I started using the instrument about a year ago. As per this morning, the readings still persist around the 0.150 to 0.160 uSv mark. There does not appear to have been any serious solar events. The weather here has been sunny, up to 33 C hot and humid.”



Category 4 cyclone Lam also hit the Northern Territory of Australia, as category 5 Tropical Cyclone Marcia hit Queensland Australia. For two cyclones to hit Australia at the same time is very unusual.

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