Saturday, September 22, 2012

Uranium APEX Mineral

Uranium (U #92) is the next element on the periodic table for my APEX mineral collection.  

I skipped Protactinium (Pa #91) which is radioactive and exists only in extremely trace amounts.  

Wikipedia Uranium
Uranium Minerals - There are many 
Uranium minerals.  
Uraninite (UO2)(Uranium Oxide) with 88% Uranium is the obvious APEX Mineral.     

Uranium is the LAST element for my APEX Mineral collection for MEOWSER.  All elements past Uranium are radioactive.  Except for rare natural transmutation reactions, they do not exist except in man made nuclear reactors.  
Uranium has very high density, being approximately 70% denser than lead.  It reacts with almost all nonmetallic elements and their compounds

Uranium is weakly radioactive because all its isotopes are unstable. 
  • 99% of Uranium ores contain Uranium-238 with 4.5 billion year half-life.
  • 1% of Uranium ores contains Uranium-235 with 700 million year half-life.  
U-235 is the only natural element that is fissile (capable of sustaining a nuclear chain reaction).  The enrichment process to recover U-235 for nuclear weapons (90% U-235) and nuclear reactors (5% U-235) is quite complicated.  The unwanted enriched U-238 is called Depleted Uranium and is used as a metal for high density weapons.
In West Africa, about 2 billion years ago, many natural nuclear reactors commenced operation in a rich deposit of uranium ore deep underground. 
U-235 concentration back then was 3.7 percent instead of todays 0.7 percent
These natural chain reactions continued for about two million years before finally dying away.  A study of these sites shows there has been little movement of radioactive waste in the 2 billion years since then.
Proponents of underground nuclear waste disposal cite this evidence to support their views.
Uranium was unknown until modern times.
Uranium is primarily used for fueling nuclear reactors.  
Depleted Uranium is used by the military to create high-density armor penetrating ammunition.
Uranium has no known biological role.
The story of Uranium is the story of the Universe.  Here is my version of this story.

Most stars can only produce elements up to Nickel (#28) (which quickly decays to Iron (#26)).  All these primary stellar nucleosynthesis reactions OUTPUT energy (yes, the star is hot!) as the elements are produced.  That is why there is so much Iron in the Universe.  Iron is basically the lowest energy state (most stable) element in a sense.

A star that explodes as a supernova creates lots of elements greater than Nickel.  The massive amounts of explosive energy are captured into successively heavier elements during the brief period of the explosion.  All these secondary stellar nucleosynthesis reactions require the INPUT energy of the supernova explosion.  All these Iron+ elements are basically storing the energy of the explosion perhaps to be released later!

Any solar systems which later coalesce from this supernova blast cloud will then have lots of fancy elements greater than Nickel (e.g. Copper, Silver, Gold, Uranium, etc.).  Earth contains many elements greater than Iron so it was created from the gas cloud emanating from supernova explosion(s).  

Earth is 4 billion years old.  Any of the Iron+ supernova elements which were radioactive are mostly long gone.  The only ones left are the most stable ones.  

Uranium is one of the remaining supernova elements on Earth.  It's half-life is 4.5 billion years.  It is the ONLY remaining element, with all of it's stored supernova energy that is still available to us as a fissile material.  Mankind is very smart and has discovered the secret of unleashing this leftover supernova energy in very productive and destructive ways!
Uranium (and its brother Thorium) are the primary source of all radioactive materials on Earth.  Uranium itself is unstable and radioactive.  When it decays it creates a cascade of very nasty radioactive elements you don't want to mess with.  At some point the decay chain arrives at Lead (#82) and safety.  This is one of the reasons there is so much Lead.  Below are the 3 main decay paths creating all these elements.