There's no guarantee that levels measured at a few specific sites will fall by half in 30 years, because contamination can migrate from areas of stronger concentration to the area where the measurements are taken. It can even go up.
But it's an incontestable fact that half of the total cesium will be gone roughly every 30 years.
I notice that you didn't cite any source for your information concerning the half-life of Cesium 137 at Chernobyl. Since you don't seem to trust info from the INTERNET, where did you get your information?
What makes you think that the INTERNET says only one thing? You can find all sorts of nutty ideas on the internet (and enenews is a great place to find them).
You can google "Cs137 half life" and likely come up with scores of resources. They'll all say the same thing because it'd a physical constant. It isn't open to opinion or debate. In fact, it's right there in the text that you posted.
Recent tests are showing that the Cesium 137 release at the Japanese explosion is four times greater than Chernobyl.
No. They don't. They took an iodine equivalent calculation for the cesium from Fukushima and compared it to the cesium emissions from Chernobyl (without applying the same conversion). That's either ignorant or dishonest, because iodine equivalency means multiplying by a factor of 40 (because of the longer half-life). If you compare "apples to apples", Chernobyl put out about ten times as much cesium. And that compares one reactor to three.
That's on an island
The fact that it's an island means that far less of the contamination fell among populated areas. I can't imagine why you think that's a bad thing.
And, if you can believe it, they are beginning construction of another nuclear plant.
Actually, they're continuing construction on a plant that was close to being finished.
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