|From supplemental materials at the DOE website.|
Perhaps you, like me, did not know that there is a place in Berkeley that was so contaminated with plutonium from the WWII race for the bomb that the Department of Energy made it a point to put it on the list of Really Contaminated Places That We Had Better Clean Up Or The Public Might No Longer Let Us Do What We Want.
You may be surprised to learn that this supposedly cleaned up radioactivity of which I speak was, to my surprise, on the University of California, Berkeley, campus.
How contaminated was it? Probably not very. They must have done something about it. Right? After all, aren't their classes held there?
According to the DOE, the remediation of the site was completed in the Eighties. Remediation is supposed to mean 'brought to an acceptable level, of no harm to human health.'
Well! Good thing all that dangerous plutonium -- in the walls, in the floors -- was all cleaned up, right?
It depends on what the definition of "clean" is. More importantly and ominously, it depends on what lower threshold you consider acceptable for a person's -- sometimes a professor or graduate student, most often an undergraduate's -- exposure to plutonium.
|from the 2014 Class Schedule, emphasis mine.|
If it doesn't hurt your head too much, you could follow the global nuclear industry's lead and call this acceptable level, no doubt used as the target endpoint for any cleanup, the "natural background level" for plutonium.
No, I am not kidding. Yes, they do that.
Of course, you may think. Perhaps you can handle that. after all, its not very much, right? Or it wouldn't have been approved as acceptable....
This option is a bit difficult for me, since, as you may recall, plutonium is almost exclusively encountered as a man made element. The levels referred to as "natural" and "background" are, as in the case of all trans-uranic radioactive substances, not the product of geological processes and have not been there, in the background, unchanged, for millions of years.
No, they have only been there since roughly the middle of the last century, and they have been continuously rising. Overwhelmingly the direct consequence of human activity, such as bomb tests and power plant, uh, anomalies.
More importantly, one particle of plutonium, inhaled, will certainly kill you, sooner or later.
Keep that in mind as you read the following, from the DOE website, Office of Legacy Management, emphasis, in red, mine:
History—Gilman Hall is a four-story building on the campus of the University of California, Berkeley. Floors, wood sills, walls, and baseboards in the building were contaminated by radioactive materials during the 1940s while conducting research on the production and chemical properties of plutonium performed in support of the Manhattan Engineer District and the U.S. Atomic Energy Commission.
DOE designated the site for remediation under FUSRAP in 1979. Lawrence Berkeley Laboratories
completed remedial action of the site in 1983. In 1985, DOE certified that the condition of the site was radiologically acceptable for restricted use, such as research and instructional purposes.
Final Conditions—Other than operating within the controls of the University of California’s state general license, no institutional controls are in effect at the site. DOE does not require on-site monitoring or surveillance. Office of Legacy Management activities consist of managing site records and responding to stakeholder inquiries.
Be seeing you.