Massive Xenon 133 plume at our doorstep

Xenon 133 is one of the radioactive noble gases that offers proof of uranium decay.  It has a half-life of 5.2 days.  To become stable, this gas will discharge a beta ray with an energy of about .233 Million electron volts and decay into its stable daughter product cesium 133.  In about 30 days, activity will drop to about 1%.

Now, being able to visually recognize this plume provides only part of the equation in terms of what our exposures will be.  We also need to understand the concentration (in Becquerel) to determine an absorbed dose.

Occupational exposure limits set by the NRC are at 1 x 10-4 μCi/mL of air.  Since i don't have a value in becquerel, it's quite impossible to get an accurate estimation.  Before anyone decides to panic, keep in mind that counts per minute readings along the west coast have stayed within normal background limits, so concentrations of Xenon 133 are likely negligible.

Namie, Fukushima Prefecture [located 20km from Fukushima] is now reading 1600 times normal background.  It rained in that area last night, so that probably has a lot to do with it.  That works out to about 140 rem per year - an absolutely unlivable value, 280 times above the recommended maximum permissible dose for the general population.

Tokyo and Yokohama readings are within normal limits according to today's data.

Update:  Apparently, the above was a theoretical simulation based on an assumed isotope releases and actual values can't be confirmed.  Explanation as follows: