Fire at the Savannah River Site

There was a fire at the Savannah River Site, the big nuclear weapons research and production complex located near Augusta, GA. It started around 5pm, and an emergency was declared at 5:39pm last evening. The FAA also put up a temporary flight restriction. Should you worry about a radiation leak? TL;DR: it doesn’t seem like it.

Today, radiation is measured in microsieverts (uSv). There are two factors: rate and total dosage, and both matter. Exposure to low levels of radiation over time increase your chances of cancer and other disorders. A “prompt” (all at once) dose at high levels causes cell destruction and a lot of potentially nasty effects.

In midtown Savannah, the normal background rate is on average around .125 uSv/hour. It’s mostly caused by minerals washing down from the Appalachian mountains in the form of sand containing thorium. That’s just over 1000 uSv a year. By the way, this often dupes people who go out looking for the Tybee Bomb. The “black sand” we have around here is rich in Thorium, and the waves and currents often create clumps that will cause a Geiger counter to spike. If you don’t know what the numbers mean, it can give the unwashed a scare!

But our background level is well below average, which is around 2400 uSv/year. Places like the mountain west jack up the average due to all the rocks that, like our Appalachians, contain radioactive materials. Interestingly, the maximum yearly limit for artificial radiation exposure for a member of the public is 1000 uSv, lower than even Savannah, so I guess the Feds will fine mother nature 😛 ?

The maximum permitted dose for a radiation worker is 50,000, and the lowest level of exposure where it is thought that you start to see additional cancer cases it 100,000, but there is a lot of argument over where than line should be. You don’t start to get detectable immediate symptoms until the levels are over 500,000 and it is at over a million where things get bad quickly.

Depending on the type of X-ray, that will get you a one time dose of 100 to 400 uSv, a CT around 10,000. Radiation therapy for cancer patients can be over a million uSv at the high end.

Right now in Savannah, levels do seem a bit above normal, but I haven’t been watching closely recently (resuming automated real time monitoring is on my to do list). It’s hovering between 0.2 and 0.3 uSv/hr. I don’t think that is due to the SRS problem, because the winds should be blowing the plume away from Savannah …

There are a lot of natural variations for low level background. Rain will cause it to spike, due to particles from all of the fallout still in the atmosphere from atmospheric testing of nuclear weapons in the 1950s! But the levels we are seeing right now are trivial.

Will keep watching, and wait for further word from SRS as to what happened (not really holding my breath on that one).