Going Nuclear

Going Nuclear

    One wouldn't consider the Grand Canyon as radioactive, but in fact there are creeks now considered contaminated and undrinkable...and all because of mining for uranium.  Way back in the 1930s, it was a small nugget of gold that led to the folly of mining in the park; there was no gold there to speak of, but that didn't stop the miners from searching for anything else.  And when a Geiger counter went off the charts at an abandoned mine just outside of the park, the search began.  And despite a 20-year moratorium on uranium mining in the area issued by President Obama, Congress is still opposing the ban, mining at any costs implies the piece in Sierra...but then as the saying goes, water knows no boundaries.

    Uranium comes in several forms and is better described by the Institute for Energy and Environmental Research.  Discovered in the 1700s, uranium (according to the Institute): ...consists of three isotopes: uranium-238, uranium-235, and uranium-234.   Uranium isotopes are radioactive.  The nuclei of radioactive elements are unstable, meaning they are transformed into other elements, typically by emitting particles (and sometimes by absorbing particles).   This process, known as radioactive decay, generally results in the emission of alpha or beta particles from the nucleus.   It is often also accompanied by emission of gamma radiation, which is electromagnetic radiation, like X-rays.  These three kinds of radiation have very different properties in some respects but are all ionizing radiation–each is energetic enough to break chemical bonds, thereby possessing the ability to damage or destroy living cells...The property of uranium important for nuclear weapons and nuclear power is its ability to fission, or split into two lighter fragments when bombarded with neutrons releasing energy in the process.  Of the naturally-occurring uranium isotopes, only uranium-235 can sustain a chain reaction– a reaction in which each fission produces enough neutrons to trigger another, so that the fission process is maintained without any external source of neutrons.  In contrast, uranium-238 cannot sustain a chain reaction, but it can be converted to plutonium-239, which can.  Plutonium-239, virtually non-existent in nature, was used in the first atomic bomb tested July 16, 1945 and the one dropped on Nagasaki on August 9, 1945.  The detonated bombs over Hiroshima and Nagasaki each held about 2 pounds of fissionable material and were purposely detonated at a high altitude for maximum dispersion.  At Chernobyl, the amount of material was 2 tons of fissionable material, and had no way to disperse.  On a side note, the half-life of U-238 is about 4.5 billion years; for U-235 (the uranium which is more widely used), it is just over 700 million years.

   In any case, uranium holds a lot of power.  To power a typical nuclear power plant, just 3-5% of enriched uranium is used; but jump over to "highly enriched uranium" --the stuff of nuclear bombs, research reactors and some large naval ships-- and the usage jumps to 90% (explains the piece from the Institute: Uranium is generally used in reactors in the form of uranium dioxide (UO₂) or uranium metal; nuclear weapons use the metallic form.  Production of uranium dioxide or metal requires chemical processing of yellowcake.  Further, most civilian and many military reactors require uranium that has a higher proportion of uranium-235 than present in natural uranium. The process used to increase the amount of uranium-235 relative to uranium-238 is known as uranium enrichment.)  And why uranium and not a more stable (but equally powerful) element such as thorium?  Primarily, says Discover, because of a Cold War political decision...uranium could produce plutonium.

    And we're back to bombs.  Unlike the many 500-to-4,000 pound bombs which were dropped over Germany during WW II (many remain buried and unexploded --some 2,000 tons each year are still discovered in backyards and parking lots in Germany and even England and have to be diffused or detonated-- all detailed in a fascinating piece in Smithsonian) the size of today's nuclear weapons are puny as they evolve into warheads atop missiles or even capping artillery shells (as was used in the coalition war against Saddam Hussein); but their power is exponentially larger (you can get a quick glimpse of this at a graph from Visual News).  And visit Wikipedia to get a quick summary of just how many nuclear weapons have been created and by whom. Scary stuff, and all part of the estimated 15,000 weapons still in possession of many countries (a quick list and the earlier summit talks is provided by the NBC site). 

    But let's jump to the beneficial side of nuclear power.  In 31 countries, nearly 500 nuclear reactors or either already operating or are under construction, according to the European Nuclear Society.  And while the U.S. is rethinking its own nuclear reactor schedule (only one has gone online since the year 2000), it is by far the leader in the number of reactors as shown in these graphs from the ENS.  

Nuclear reactors being constructed

Nuclear reactors in operation

   
    There's been a bit of rethinking about nuclear power, not only from the safety in the designing of the reactors themselves, but also what happens should a disaster strike (either man-made or naturally).  One such story appeared in Bloomberg Businessweek which talked about this declining interest in nuclear power: Stunting the renaissance before it got going were the 2008-09 recession, the 2011 Fukushima Daiichi disaster, and especially the proliferation of cheap natural gas.  Nuclear, which provides 19 percent of U.S. electricity and two-thirds of the country’s emission-free power, has arrived at a perilous crossroads.  Four nuclear plants have shut down over the past several years because of recession-stifled demand and inexpensive gas.  Eight or nine more are in danger of premature retirement for similar economic reasons.  Which brings up the next issue...most nuclear reactors are at the end of their life expectancy.  Tearing them down is almost as expensive as building them (France's Areva is desperately trying to promote its new and safer designs, but continues to have problems as recently mentioned in the U.K.'s Telegraph).  A reactor can last up to 40 years (some of the later designs can last an additional 20 years)...but then what?  Now comes talk of new material such as silicon carbide ceramics...but then, I heard all of this nearly 40 years ago.  Hiking in Zion National Park, I happened to befriend a nuclear physicist and as differing as our views were, we were soon bonding and hearing each other's side (we remain friends to this day)...even back then, he was puzzled at the resistance to using ceramics.  It works best at the temperatures that concrete melts, he told me (concrete is still the main material used in building the shells and containment facilities of nuclear reactors).  As for the "spent" fuel, you seal the rods in glass, then in concrete, then in a lead shell, then store them...100,000 years before the radioactivity breaks through, he said.  By then, he said, there should be a solution as to how to properly dispose of them.  But there was resistance even for that.  As a nuclear engineer working on such reactors (only a few had been developed), he said that both he and other physicists couldn't understand why countries were so against such safety measures (perhaps cost, I asked).

    And so here we are, nothing detonated yet but reactors aging (Germany is retiring each of its reactors as it reaches the end of its life cycle...a position which has its own opponents) and countries such as India and China needing ever more power (and trying to break away from the pollution of its coal-fired plants).  And then there are more and more unstable governments working on developing or enhancing what nuclear weapons they already have.  If this worries you a bit, then you might not want to read Eric Schlosser's book from 2013, Command and Control which described the accidental dropping of two nuclear bombs in the U.S. (they were being transported to the U.K.): When the lanyard was pulled, the locking pins were removed from one of the bombs.  The Mark 39 fell from the plane.  The arming wires were yanked out, and the bomb responded as though it had been deliberately released by the crew above a target.  The pulse generator activated the low-voltage thermal batteries.  The drogue parachute opened, and then the main chute.  The barometric switches closed.  The timer ran out, activating the high-voltage thermal batteries.  The bomb hit the ground, and the piezoelectric crystals inside the nose crushed.  They sent a firing signal...that was back in 1961 and the bomb fell over North Carolina (the NY Times, among others, reviewed the interesting and engaging book)...nuclear weapons are no longer allowed to be transported by air over U.S. soil. 

    Radiation surrounds us, some of it benign and some of it harmful.  But there are more powerful elements than uranium, such as neutrinos, those pesky sub-atomic particles that are a thousand times stronger than our largest particle accelerator...and those neutrinos are all around us as well.  As we again enter a world where we seem to feel that larger is better --more boisterous campaigning, more powerful, more loud-- we might want to look at the smaller things, for hidden inside rocks and in air we cannot see, seems to rest the true power that we seek...perhaps yet another example of what we still need to learn from this life.