Monday, March 21, 2011

to put things into perspective...

Another dispatch from our PTA Prez (and expert in matters nuclear) came through earlier today (thanks Conny and Tara for distributing):

BST Parents,

Two things that may be confusing in nuclear terminology are radiation and contamination. The definition of contamination is radioactive material outside of a controlled area, or somewhere that you don't want it. So image that we are all sitting around a campfire in the woods. The fuel is the stack of burning sticks. The radiation is the light given off by the campfire. No matter how hard the wind blows, or what direction the wind blows, you will still see the same amount of light (radiation). Thus, when we think of the reactors at Fukushima, the wind direction will have no effect on the amount of radiation that is emitted.

Now as were are sitting there roasting our marshmallows, we see burning embers drift up and float away from the fire ring/ fire pit. That would be our contamination. The ember leaves the controlled area (fire ring/ fire pit) and carry light away from us. The wind does effect where the contamination goes. The contamination consist of radioactive material but typically the amount of radiation emitted is much less than the source. That is, we still have much more light from the campfire than we do from the embers.

So as I am scanning through different news sources I see men in white suits holding a very sophisticated gadget over the head of an innocent little girl with headlines reading "XX number people diagnosed with radiation". What he is doing is looking for contamination. That is, he is looking to see if she has any embers from the campfire on her. This process (called frisking) is a standard procedure at every power plant for every person leaving the plant every time; during normal operations and shutdowns. Why? To make sure that you don't accidentally take radioactive material outside of the plant. What the headlines should read are "XX number of people found to have a radioactive particle on them and the particle was removed instantly and they were sent on their merry way". But I guess that most likely more accurate headline doesn't sell as many papers.

I do not want to minimize the seriousness of this situation. We do not want contamination (or radioactive materials outside of the reactor) and it is important that people are checked. But once the contamination is discovered and removed, the threat to human health is gone as well. I take the ember off of your shirt and you longer emit light.

Ingesting or inhaling contamination is more serious because it is more difficult to get it out of you. But, depending on what you ingest/ inhale and how much, there are a wide range of things to take into consideration. IF, and again a big IF, there is contamination in the food or water, the risk to human health depends on how much there is and what it is.

Below is a FB entry from a former nuclear colleague of mine:

The radiation levels in Tokyo are elevated. We are now hearing that elevated levels are also being found on the West Coast. Should we worry?

Well, it depends on how paranoid you are. If you live in a brick house, have granite counter tops or spend time in your basement, you might want to think about changing your lifestyle. These all give off elevated levels of radiation.

Lots of things give off natural radiation. It's a fact of life. The cumulative reading of it is known as "background radiation." What is being reported in the news is typically the increase above background. The increase is very small and barely detectable right now on the West Coast (the most sensitve equipment can barely detect it).

To put things into perspective, at the current elevated levels in Tokyo (assuming that they stay elevated for an entire year) a resident who lived there for that entire year would receive 474 microsieverts. In comparison, those fleeing the country and heading to New York will receive about 100 microsieverts in just 15 hours from the plane ride itself.

As a nuclear worker I strive to keep my exposure as low as possible. My limit is 50,000 microsieverts/year. However, in a busy year, I usually get less than 10,000. Much, much greater than what people are being exposed to in Tokyo.

I'm not implying that the levels should be ignored; they just need to be put into perspective. I fly over 100,000 miles per year. My exposure from flights each year is usually greater than what I pick up working in the plants.

Here are some questions that I got the other day:

I understood that at Chernobyl, one of the problems was that the core was kept cool with graphite instead of water which enabled the radioactive material to travel considerable distances when it exploded from the core. That can't happen at Fukushima, can it? because it is not the core that is causing explosions, and it is cooled with water?

Yes, the Chernobyl reactor core and systems were much different from Fukushima. I don't know enough about graphite cores to comment on how much more they would spread radioactive material if breached. Correct, at Fukushima it wasn't the core that caused the explosions, it was the hydrogen gas that was vented to the inside of the reactor building that exploded.

What can they do to get things under control at Fukushima? Will they get battery operated water cooling systems in until the electricity is back up and running? Dropping water from the air seems so desperate.

They have to keep the fuel in the core 'cool' no matter what. My understanding is that batteries last for 8 hours. I do not know if replacing the batteries before getting the electrical back up is/ was a viable option. Having consistent electrical supply is the better solution than batteries or diesel run pumps. Yes, dropping water from the air is desperate.

I am still looking forward to seeing you all back at school.



No comments: