Plume forecast for Japan: 4/16

Winds are expected to maintain a north/northeastward orientation through the early morning and afternoon of Saturday April 16 Japan Standard Time (JST).

The “feed and bleed” strategy of adding water then releasing the radioactive steam continues, as well as possibly elevated airborne levels due to the issues at the reactor 4 spent fuel rod pool (mentioned in the 4/15 post).

“TEPCO estimates the fight to stabilize its crippled Fukushima reactors will last through June, leaving them vulnerable to more aftershocks and radiation leaks, a person briefed on the utility’s plan said.”

The Naval Research Laboratory’s skillful data-assimilating triply nested (45 km/15 km/5 km) mesoscale meteorological model COAMPS produced the fields above, using a passive tracer to map the expected plume trajectory.  Lighter gray contours show more concentrated material.  Each shade of gray represents a factor of 10 difference in tracer concentration. [Plume images are a research tool; contours are arbitrary units for visualization purposes.]

The modeled “plume” is a tracer that is released at a constant concentration, simply follows the air flow, and (a) does not settle due to gravity, (b) does not get deposited with rain, and (c) does not have any radioactive decay.  These neglected factors typically dramatically reduce the effects of radiation when it travels over distances of hundreds of miles.  There is much uncertainty in the source term, as the releases of radiation that occurred in the past were highly intermittent.  (So although modeled as such, the plume in actuality was not a continuous release.)

We have utilized COAMPS to make detailed and accurate forecasts of various coastal regions, including large-scale (synoptic) weather patterns.  It also is skillful at simulating local coastal processes such as the influence of cold upwelled ocean waters, or sea breezes, when there is no strong synoptic forcing.  We have previously used the model to simulate the movement of hypothetical releases along the east coast of Japan.

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