That's where environmental pathway modeling (EPM) comes in. EPM, in simple terms, is the combination of the considerations for radionuclide spread in the air, the ground, and the water, taken into account at the same time. Factors like type of contamination source, whether it's in a container, the local geography, environment, sources of water above and below ground, and many others are considered. The figure below shows a highly simplified diagram for contamination considerations. [1]
The Environmental Protection Agency (EPA) spends a lot of time and money on EPM. They have researched and developed several models for different radiation hazards in different environments. [2] So in the event of a contamination event, what do they do?
First, they make many simplifying assumptions to get a general idea of what kind of hazard they're dealing with. Assumptions such as initially ignoring any shielding that may be around the exposure point and treating the exposed area as homogeneous. This allows simpler, easier models to predict immediate courses of action while specific data relevant to the site is gathered. Once they know more, they can slowly remove assumptions until a model can be developed for the exact problem they face, and the most educated choices can be made in how to contain and control the area, and protect downgrade areas from contamination.
As we discussed before, there is very little (approaching zero) chance of a nuclear power plant endangering you. But in the unlikely event something does go terribly wrong, those in charge won't be leading blind; research is constantly ongoing to be better prepared to predict and react to a contamination.
[1] http://www.atsdr.cdc.gov/hac/phamanual/ch6.html
[2] http://www.epa.gov/sites/production/files/2015-05/documents/540-f-94-024.pdf
What I found interesting is for atmospheric modeling they split everything into two basic pathways:
ReplyDelete1. Particles with an "aerodynamic" diameter less than 10 um.
2. And those with aerodynamic diameters greater than 10 um.
The assumptions and models used are extremely different because the smaller particles will travel further, stay in the air longer, seep into the soil more, and they'll be overall harder to track.
do you know more about the definition of "aerodynamic" diameter, as opposed to simple geometric diameter?
Delete"The aerodynamic diameter of an irregular particle is defined as the diameter of the spherical particle with a density of 1000 kg/m3 and the same settling velocity as the irregular particle"
Delete-From Wikipedia
So it's the small aerial particle corollary to a hydraulic diameter. Allows for a simplified but still accurate analysis of the motion of an otherwise complicated particle.
This kind of information is a great source for people to get a sense of security about the nuclear industry. Many think that the industry is not prepared to handle accidents and even that these accidents are common. This mentions how the industry is constantly preparing its arsenal against unlikely accidents.
ReplyDeleteHow accurate are the "simplified" models? I presume they are accurate enough to provide beneficial information (otherwise they wouldn't use them), but what is the advantage of more advanced models over the simplified ones?
ReplyDeleteThe simplified models allow for quick decision making--early, broad strokes on the path to controlling a contamination. They'll identify the most prevalent means for the spread of contamination, and what areas are most at risk. The more advanced models can help more in the small details specific to the situation, but take more time and information to utilize.
DeleteI agree that this information is very helpful in trying to show people that there is no reason to fear a nuclear power plant. The first step is making them realize how low the chance is of an accident actually occurring. But since most people already have it in their head that it's pretty likely (even though it's not), showing them that extensive research and modeling has been done to deal with such an accident and continue to keep the public out of harm's way.
ReplyDeleteThis is true, and unfortunately there's some people out there (including some in important, influential positions) who will never be convinced that the dangers they've heard about are misconceptions. Still, it's part of our job as future members of the industry to quell ignorance as much as possible.
DeleteVery interesting post. You are right in that we need to advocate on behalf of nuclear energy to reduce the irrational feel of this energy source. Especially during election season, it is important that we understand the views of nuclear energy by all the political candidates when making the decision on who we will vote for
ReplyDelete