Environmental pathway modeling is a figure detailing each way radioactive contaminants can be released into the environment and make it back to humans. The model shows the source, environmental medium and transport mechanism, exposure point, exposure route, and potentially exposed populations. A great article for working through model examples can be found here.
Think of it like group of kids peeing in one specific ride at a water park. Now, like a nuclear plant, the water park rides have filters to keep the water clean and circulating. Assume that these kids pee in the water and the systems fail so the same water keeps circulating. The source would be the kids peeing. The environmental mechanisms would be the pool itself as well as leakage along the ground from splashing/overflow, that pee-water circulating through other pipes near other areas of the park, and people wet with that water walking around to other areas of the park. The exposure points would then become the ground covered in pee water, drips and splashes from the water, any leakage from pee water pipes, and anywhere the wet people touch or go swim afterwards, The pee concern is similar to radiation in that no one wants to eat or be covered in it, therefore the exposure routes would be getting any of those exposure routes in your mouth or getting it on your body either by swimming in it, walking in it, or otherwise touching it. The potentially exposed population can be the water park workers, guests, or even the general public outside the gates all being contaminated with pee water.
If this wasn't a graphic enough description of it, make a good investment of 2 minutes of your life and watch a clip of the South Park episode I saw fit to make the title here. I wasn't able to find the full episode on Comedy Central's website but if you're courageous, you can find some links on Google.
All jokes aside, this method is useful for analyzing how contaminants more through the environment but it is only as good as how creative its maker is. There are many ways contaminants can travel and unfortunately we find out too late that people are dying and after some backtracking, we connect the dots and figure out a new pathway. There are a lot of modeling codes and analysis tools available (probably not freely) to help with this but again, they are used to assist but not define contaminant movement. Hope today wasn't too vulgar or immature, thanks for reading!
-Michael
I was so excited to read about something non-pathway related, and then the first sentence sucker punches me. But then there was a urine analogy, so it was worth it.
ReplyDeleteAs thanks, here is an easily answerable question: what is an example of a system meant to contain radiation in a nuclear power plant from getting to the public?
Florian, my dear fellow classmate, I am overjoyed that you asked this question. There are multiple systems used to prevent radiation from escaping to the public. We usually call these systems barriers. They are as follows:
Delete1. The integrity of the fuel pellet
2. Fuel cladding
3. The reactor pressure vessel and its primary coolant system.
4. The containment building.
5. The site's distance and isolation away from a large population.
Number 5 is not explicitly stated always, but it definitely makes sense when considering it.
Wow thanks Dj! That's some great information. Don't forget that if the accident if bad enough to get past the first 3, steam and other fission gases rise while corium will fall to the bottom of the containment building. Point being, without some emergency systems, those two will blow or melt through everything. Florian, to cool stuff the industry has high and low pressure water injection into the core as well as cooling sprays in the building itself. These dispersion models can be used to model regular waste and operating radiation as well as accident scenario "Oh crap!" kinds of radiation releases. Thanks for the question!
DeleteUsing this urine analogy, it's really interesting because Turkey Point Nuclear Generating Station has a small leak of their cooling canals (primary water from the core heats secondary water which spins the turbine and is then cooled by water from specific canals). Officials detected high levels of tritium in Biscayne Bay, which is next to the plant, indicating that water may be escaping the cooling canals (http://www.miamiherald.com/news/local/environment/article64667452.html). In the pee analogy tritium would be pee in other areas of the park. Though there is currently no immediate cause for concern, the leakage of the canals will require correction.
ReplyDeleteThat's exactly the way I was thinking when I wrote this! And using the rest of the modeling analysis, Biscayne Bay plants absorb that water, and suddenly you've got a bunch of radioactive manatees migrating north leaving radioactive manatee poop north in rivers and springs.
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