Oklo also demonstrates a way to store some forms of nuclear waste that were once thought to be almost impossible to prevent from contaminating the environment. Since the advent of nuclear power generation, huge amounts of radioactive xenon 135, krypton 85 and other inert gases that nuclear plants generate have been released into the atmosphere. Nature’s fission reactors suggest the possibility of locking those waste products away in aluminum phosphate minerals, which have a unique ability to capture and retain such gases for billions of years.
The Oklo reactors may also teach scientists about possible shifts in what was formerly thought to be a fundamental physical constant, one called _ (alpha), which controls such universal quantities as the speed of light [see “Inconstant Constants,” by John D. Barrow and John K. Webb; Scientific American, June]. For three decades, the two-billion-year old Oklo phenomenon has been used to argue against _ having changed. But last year Steven K. Lamoreaux and Justin R. Torgerson of Los Alamos National Laboratory drew on Oklo to posit that this “constant” has, in fact, varied significantly (and, strangely enough, in the opposite sense from what others have recently proposed). Lamoreaux and Torger son’s calculations hinge on certain details about how Oklo operated, and in that respect the work my colleagues and I have done might help elucidate this perplexing issue.
Were these ancient reactors in Gabon the only ones ever to have formed on the earth? Two billion years ago the conditions necessary for self-sustained fission must not have been too rare, so perhaps other natural reactors will one day be discovered. I expect that a few telltale wisps of xenon could aid immensely in this search.