Nuclear power is often offered as a climate friendly energy source, albeit not without some security risks. One of those risks – the half-life of spent nuclear fuel, or the amount of time until the waste is no longer radioactive, is of particular concern.  Spent nuclear fuel includes lots of radioactive elements that take a long, long time to become safe. Here’s a quick look at how long is long:

The half-life of Iodine-129 is 15.7 million years. To put this in context, fifteen million years ago was a full ten million years before the predecessor to humans, Australopithecus afarensis, appears in the archaeological record (read 10 million years before the opening scene of “2001 A Space Odyssey”).

The half-life of Neptunium-237 is two million years. Two million years ago, ice covered much of the Earth and mastodons, woolly mammoths, hairy rhinos and saber-toothed cats were living out their lives.

The half-life of Technetium-99 is 211,000 years.  Our Neanderthal cousins had just started using stone tools around 200,000 years ago.

The half-life of Plutonium-239 is 24,200 years.   Twenty thousand years ago was over ten thousand years before the first known city and the emergence of agriculture.

Thinking back on the world 15 million years ago, a time before language; 24,000 years ago, a time of cave paintings; and 5,000 years ago with the emergence of the first written language, cuneiform, it is difficult to imagine how we are going to be able to communicate to future generations: “Hey don’t touch that – it’s radioactive.”

Let’s hope there will be a Rosetta Stone to translate the risks of all of our nuclear waste for generations to come. Maybe Hal 9000 will be there to help.