Chernobyl Area Survey Finds Lasting Problems For Wildlife

ninguna writes "The largest wildlife census of its kind conducted in Chernobyl has revealed that mammals are declining in the exclusion zone surrounding the nuclear power plant. While some stories seem to indicate nature is recovering, the actual picture isn't quite so great."

Comments

How long till 'clean'?

[Great Big Bird]

Has there been any indication of how long Chernobyl will be uninhabitable by our species?

Re:How long till 'clean'?

[martas]

all true, and besides, even today there are many populated areas in the world that are probably as, if not more, dangerous for humans as chernobyl - http://www.time.com/time/specials/packages/completelist/0,29569,1661031,00.html

Re:How long till 'clean'?

[TrisexualPuppy]

I spoke with a bio professor about this a few years ago before I went on a trip to the Ukraine to do the "canned" Prypiat/Chornobyl tour. The abundance of wildlife is misleading. Since there is no human competition, there is going to be a lot more wildlife. But much of it has a higher mortality rate and isn't without its share of defects.

He mentioned that for humans to live there, we're probably easily looking at 100-500 years before the radiation is at acceptable levels. Once the wildlife have fewer problems (e.g. thryroid disorders), it may be safer for humans to move in. A good experiment would be to take a sampling of various types of wildlife--perhaps the ones most sensitive to certain radiation effects--and record the data on a yearly basis. Once the animals stop succumbing to radiation effects, it might be safe to move in, but you're going to have to consider other problems such as plant sequestration of radioactive isotopes. That birch may burn really well in the wintertime, but how much I-131 has it taken in (just a hypothetical statement)?

Re:How long till 'clean'?

[CrimsonAvenger]

And the SF crew carried radiation detectors that were "ticking" frequently enough to indicate the area is still filled with radiation.

Just fyi, you can adjust the settings on those things quite a lot, so that they tick with even tiny amounts of radiation. Or so that they don't tick very much with quite large amounts.

And the scifi channel has an interest in making it look hazardous, since the show is pretty pointless if everything is pristine....

Re:How long till 'clean'?

[Deathlizard]

I've seen estimates from 200-10000 years depending on how close you are from the reactor.

What I don't understand, is why isn't this area used to build more nuclear reactors? It's not like there's anyone there to scream NIMBY, or that it'll be a bigger disaster if another reactor goes boom, which shouldn't happen if they use a modern reactor design. The only issue I see is employee safety, and that could be virtually eliminated given a reactor that is designed to shield the workers from the outside excess radiation.

Re:How long till 'clean'?

[mlyle]

Hotter radioisotopes have shorter half lives.

131I has a half life of 8 days. Basically all 131I released from something like Chernobyl is as a direct fission product of 235U.

Within a few months, substantially all the 131I is gone.

The "worst" things released for habitability, then, are the things with intermediate half-lives of a few years. The worst of these is the ~100 gigabecquerels of 125Sb released, and the 500-600 gigabecquerels of relatively short-lived isotopes of Cesium.

At this point, open-air dose rates and ground dose rates are about 1/100th of the first day dose; further gains are going to be slower because longer-lived isotopes dominate, but will be another factor of 20 in the next twenty years. Viewed another way, someone who spends their whole 75 year life in the present exclusion zone starting twenty years from now will receive a lower dose than someone who experienced the first ten days after the accident, and very few of those people died. (And there's considerable evidence that acute, high doses are much more dangerous than an equivalent dose delivered over a long time).

(According to UN reports, less than 50 deaths; most of which were emergency workers, but included 9 children who died from thyroid cancer from 131I).

Re:How long till 'clean'?

[Artifakt]

It's an interesting comparison you offer, but I'm not sure what conclusion should be drawn as to safety. Half life for the Antimony (125Sb) would be 1008 days, so at 30 years out, we are looking at about 1/16th of the contribution you are projecting for 20 years. The numbers you use suggest human return certainly ought to be possible within 30 years, if not 20, even erring on the side of extreme caution.
        But, I doubt there is a single mammalian species in the area that has half as long a typical time to reproductive maturity as humans. If a species such as deer or wild dogs is showing declining reproduction when they mature in as little as a single year, humans simply have to be more vulnerable to the same effects due to what's called reproductive differential. It's not really necessary to understand the effects that are causing the population decline in detail, or have a clear stepwise model of all the mechanisms involved, to predict this.* So, my estimate would be to wait until the fast reproducing species are all acting stable, and then wait another couple or three half lives of the Antimony, even if this takes more than 30 years total.

*assuming the species isn't declining because of being hunted to excess by humans or because we have screwed up the broader environment - rather that it's declining because of something originating with the Chernobyl event - we do still need to make sure of that!