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by annoyingnoob 2368 days ago
What I didn't get from any of the articles is how long the radiation is expected to be a problem. We are 60 years and its still very radioactive. How many more years before its not?
3 comments

Many generations beyond ours. Someone else posted this article which has more information:

https://www.abc.net.au/news/2017-11-27/the-dome-runit-island...

"Some of the debris buried beneath the dome includes plutonium-239, a fissile isotope used in nuclear warheads which is one of the most toxic substances on earth.

It has a radioactive half-life of 24,100 years."

Generally speaking, the longer the half-life, the less dangerous (in terms of radioactivity) something is. Also, pl239 primarily emits alpha particles, which are stopped by clothing and don't penetrate skin. Maybe a real physicist can chime in, but I don't think there's much risk of standing around subcritical quantities of the stuff.

The chemical toxicity is a different matter though.

Direct from Wikipedia:

As an alpha emitter, plutonium-239 is not particularly dangerous as an external radiation source, but if it is ingested or breathed in as dust it is very dangerous and carcinogenic. It has been estimated that a pound (454 grams) of plutonium inhaled as plutonium oxide dust could give cancer to two million people. However, ingested plutonium is by far less dangerous as only a tiny fraction is absorbed in gastrointestinal tract. 800 mg would be unlikely to cause a major health risk as far as radiation is concerned. As a heavy metal, plutonium is also toxic.

https://en.wikipedia.org/wiki/Plutonium-239

https://en.wikipedia.org/wiki/Plutonium#Precautions

Fascinating, I don't have a lot of knowledge around the subject. Thank you for the new perspective.
Part of the problem in determining that is that there is a history of reports saying that it wasn't a problem anymore.

> The last nuclear test in the Marshall Islands was conducted over fifty years ago, and through the passage of time and cleanup efforts by DOE, radiation doses in the RMI have been steadily declining. Today, the greatest source of radiation being absorbed by all persons living in the world, including the RMI, is from natural sources. - U.S. National Cancer Institute, 2010

There have been some reports in the past that disagreed with the narrative that the radiation was quickly disappearing, but they have been traditionally shot down quickly:

> ...determined that no further corroboration of the measurements and assessments of the radiological conditions at Bikini Atoll is necessary. The data that have been collected are of sufficient quality to allow an appropriate evaluation to be performed. - International Atomic Energy Agency, 1997

However, a modern study by Columbia University [0], published this year, found not just flaws in the way previous studies were done (they avoided sediment analysis), but a disturbingly high amount of radiation in places that were previously deemed to be "safe". Well above the legal limits put in place by agreements between the US and the Marshall Islands.

[0] https://news.columbia.edu/news/marshall-islands-nuclear-radi...

A quote from the article in my earlier comment;

    Some of the debris buried beneath the dome includes
    plutonium-239, a fissile isotope used in nuclear
    warheads which is one of the most toxic substances
    on earth. It has a radioactive half-life of 24,100
    years.
By your logic, Bismuth-209 must be the most dangerous element on earth, with a half-life of 19 quintillion years.

Elements with longer half lives tend to be more 'stable'...