The Green Party of Canada said despite public concern over fallout from the nuclear disaster in Fukushima, Health Canada failed to report higher than normal radioactive iodine levels in rainwater. This report contradicts official statements made by Canada's Harper Government. Has radiation reached Canada? Has radiation reached the United States? Has radiation reached California? Has radiation reached British Columbia? Has radiation reached Ontario? Is radiation dangerous? Is radiation in the air? Yes to all of the above.

1. Evidence of sharp features in the
Fukushima plume over
Southwestern British Columbia
Réal D’Amours, Alain Malo, Jean-Philippe
Gauthier et Gilles Mercier (CMC)
and
Ian Hofman (Health Canada)

2. Introduction
• Several studies on the radioactive releases
from Fukushima nuclear power plant already
exists
• The Fukushima plume provide nice
opportunities to test radioactivity detection
capabilities
• This study focusses on the arrival of the plume
over SWRN BC

3. NRCAN aerial survey March 20
18:00 – 19:00 UTC

4. Other detections:
Health Canada’s radiation monitoring network: 15-minutes time resolution
PNNL Richland, Washington: 12-hours time resolution

5. Detections on Health Canada’s
radiation monitoring network in BC
Sampling every 15 minutes

6. Sidney & PNNL Observations

7. What is going on?
• In all likelihood, the plume originates from Japan, ~8000km
away
• Naively one could expect a diffuse and well-mixed plume
reaching the West Coast, especially in the boundary layer
• Nevertheless important small scale features are observed in
the plume

8. Look at (Lagrangian) dispersion modelling results
• We use CMC’s dispersion model MLDP01 together
with CMC’s operational analyses
• Make minimal hypotheses about the source of
emission:
It is located at the Fukushima Power Plant
Sometimes after the tsunami hit (~ March 11 06 UTC)
A release rate of 1 Bq of 133Xe / hour
Assume 10 6-hour realeases from March 11, 12UTC,
ending March 14, 00 UTC
– 2 000 000 particles for each of the 10 simulations
–
–
–
–
D’Amours, A. Malo, R. Servranckx, D. Bensimon, S. Trudel, and J.-P. Gauthier-Bilodeau. Application of the atmospheric Lagrangian particle dispersion
model MLDP0 to the 2008 eruptions of Okmok and Kasatochi volcanoes. J. Geophys. Res., 115, 10 2010.
1R.

9. Results for Sidney
Correlations with observed concentrations
11-12H 11-18H 12-00H 12-06H 12-12H 12-18H 13-00H 13-06H 13-12H 13-18H
0.38
0.80
0.60
0.58
0.65
0.94
0.35
0.44
0.76
0.59

10. Position of Model particles
Release March 12 18UTC
March 19 18:00 UTC
March 20 00:00 UTC
March 20 06:00 UTC
March 20 12:00 UTC
Only particles in the layer SFC – 2000m are shown

11. March 20 1800 UTC

12. In principle the observed concentration at a point should be a combination
of the resulting modelled concentrations using sources with a « unit released rate »,
the (sensitivity factors) scaled by the real release rate:
Where the amn are the sensitivity factors
and the Sn , the source scaling factors
Here we assume a constant release rate…
Total sensitivity

14. Along Vancouver Island March 20 18-19 UTC

15. Estimating a « constant » release rate
Averarge
Sens. factor
Average Obs
Concentratio
n
Release rate
Bq / 6 hours
Aircraft
1.44 X 10-16
46.7
3.2 X 1017
Sidney
9.05 X 10-17
58.0
6.4 X 1017
PNNL
1.59 X 10-16
21.6
1.4 X 1017
Average release rate: 3.6 X 1017 /6 hours => 17 000 GBq s-1

17. Conclusions
• Dispersion modelling indicates that there are indeed
small scale / sharp features in the plume even after
several days travel times
• The accurate timing of the plume arrival is a good
indication of the high quality of CMC wind analyses
over the Pacific
• « Horizontal » diffusion does not play a major role in
the horizontal spread of the plume