The above chart shows the amounts of fission products and actitnides present in 3 year old fuel used in a PWR.
Note that the single plutonium isotope Pu-239 is found in greater amounts than all isotopes of xenon, and twice the amount of all isotopes of cesium.
The total amount of all plutonium isotopes at discharge after four years of use in a BWR is roughly 1.27%, and all fission products is roughly 5.15%.
After five years in wet storage the ratio of Pu-239 (and other transuranics) to these fission products will increase and continue to do so ad
infinitum for the next 500,000 years, as seen in the chart below.
The End Of The Beginning And The Beginning Of The End
It seems that I get amazed every day when it comes to nuclear power and nuclear weapons. Absolutely dumbfounded and amazed.
One example is how fast neutrons used for planetary destruction came into being. It took only 13 years from the discovery of the neutron to the day
they unleashed the bomb.
The neutron was discovered in 1932, and a nuclear chain reaction was envisioned the next year. Nine years later in 1942 the first nuclear chain
reaction was produced in the world's first nuclear reactor, then called a nuclear pile (which seems a more appropriate name), built under the
bleachers of an abandoned sports field.
Enrico Fermi be damned.
Three years later supercriticality was achieved and the nuclear dragon was born. At no time were the consequences of creating plutonium or other
transuranic elements studied, or even theorized. Ignorance to anything other than learning to unleash the power of the atom was the law of the
Even after scientists and the world saw the power fission could produce, they still didn't have a clue what they were dealing with. The year after
Hiroshima and Nagasaki, as stated previously, they were playing games with nuclear warheads (the demon core) called 'tickling the dragon'. Games.
Stupidity and ignorance of the highest nature.
And somewhere between then and now the nuclear industry has become full of nuclear 'experts'. People who can guarantee what any nuclear material will
do under any given circumstance, with no prior experience in the conditions they are analyzing.
Only they can't. At best all they can do is make educated guesses about a subject that no one really understands.
We have come a whiskers distance from planetary oblivion quite a few times on this planet since first unleashing the dragon, but never more so than on
March 14th and 15th. The explosions and eruptions that occurred those days very easily could have set off the SFPs at R1, R3 or R4. In fact, it's hard
to imagine how R3's SFP survived what it went through, a nuclear explosion and then heavy equipment falling on top of it. In the 1940's experiments
with the 'demon core', criticality was achieved in the first accident by merely dropping a reflective brick on the plutonium.
If the R1 or R3 SFP had gone prompt critical, from the violent jolts and intense shaking on those days, or even worse the R4 SFP collapse, most of
Japan would have become uninhabitable.
Fish in the Pacific uneatable. A high standard of living in western North America untenable.
And from there a cascade of events would issue out, doing damage in ways we have never experienced on this planet before. Damage far beyond anything
we dreamed the human race capable of, until now.
The Wigner Effect And The Beginning Of The End
I'm sure there are many who would call all of this the ramblings of a paranoid anti-nuclear propagandist. And they'd be right, especially since I've
always been anti-nuclear and propagandizing comes naturally. The paranoid part though came recently, when Dai-ichi forced me to dive head long into
all things nuclear. And what I found out did more than make me paranoid, it frightened me beyond measure. And I don't scare easily.
It all began with neutron embrittlement. This is something that should be taught in classrooms worldwide, it is that vital to the future well-being of
the human race. Yet one has to look and look hard to find out about it.
And after looking and looking hard to find out about it, all I can say is........why, oh why, didn't I take the blue pill. I was so much happier in my
other pre-Dai-ichi life. Now I count the days till we perish. I'm sorry if that sounds wildly hallucinatory but that's what the data is saying.
I have no background in any of this, so I don't know know if it's 100% accurate, but I think in general I've got the ballpark covered. And all I can
say is hold on to your seats cause Alice just fell through the wormhole into another dimension where we blow this planet into trillions and trillions
and trillions of little bits and pieces of radioactive rock. I'm just kidding of course....some of the pieces will be huge.
First a bit about neutron embrittlement. It's actually the end result of a process known as "Wigner's Disease" caused by the "Wigner Effect". This
effect has to do with pushing the crystalline structures that comprise most solids, and all metals, out of alignment. Except for glass and a few other
materials, all solids (i.e. minerals, sand, clay, limestone, metals, carbon, and salts) are composed of crystalline structures with the atoms of the
molecule held together in an organized lattice. There is a bond that holds these atoms in place, a force, an energy, electrical and/or chemical or who
knows what, I don't really understand it, but it seems to be the problem behind the effect.
They have known about Wigner's Disease since the early days of nuclear reactions. While making the plutonium at Hanford that would go into the first
nuclear bombs for the Manhattan Project, large scale radiation effects were seen that no one expected. The intense neutron flux from the reactors
displaced atoms in the surrounding graphite moderator and reactor fuel, causing both to swell.
The intelligentsia of the day had no idea this would happen until both the moderator, and the reactor fuel swelled. After investigation they found
that if a neutron or subatomic particle had enough force, it could hit an atom in the crystalline structure of any material, and push it out of
alignment, stretching it, and expanding the lattice. These dislocated atoms would still be connected to the lattice via the force that bonded them
initially to it. The force exerted by the subatomic particle that causes this dislocation is retained within this stretched lattice bond in what is
called elastic deformation.
These displaced atoms are called interstitials. The swelling was caused by the number of interstitials growing. As atoms were pushed out of alignment
but still a part of the forces holding the lattice together, they expanded while density decreased. And as the lattices expanded, the full amount of
energy creating the interstitials was being retained.
When large amounts of interstitials have accumulated they pose a risk of releasing all of their energy suddenly, creating a temperature spike.
Accumulation of energy in irradiated graphite has been recorded as high as 2.7 kJ/g. This build up of energy referred to as Wigner Energy can only be
relieved by heating the material. This process is known as annealing. More on that later.
The Transuranic Way To Real Alpha Decay
The Wigner Effect can be produced from the decay of an alpha particle (helium) as well as by neutron activation. The damage from an a-decay event
comes from two different particles. First, there is the a-particle itself. Though an alpha particle has the highest energy output of any form of
radiation, it exerts most of it's energy along its path, which is a few tens of micrometres long. It is only at the end of its trajectory that it
interacts with the crystal atoms in billiard-ball fashion, causing a few hundred displacements.
Second, there is the ‘recoil nucleus’ that is left after the emission of the a-particle, for example uranium-235 following the decay of
plutonium-239. This particle has a much lower energy, just 86 keV, but deposits nearly all of it through ballistic interactions along a path measured
in nanometers. This short but explosive excitation path has been likened to a “cannon ball awry through a crowded dance floor” and recent studies
have shown one recoil nucleus to produce as many as 5000 displacements for every a-decay event. This is known as a recoil collision cascade, and
energy deposition in this recoil cascade is high, at a few eV per atom, with temperatures in its core exceeding 5,000C.
As the scientific world continued to explore this new phenomenon of displaced atoms they found the damage caused by the a-decay Wigner Effect to
comprise a complex combination of defects. These include isolated defects from the a-decay, inclusion of alpha particles (helium) in the lattice, and
numerous collision cascades from the recoil nucleus. They also found that as they accumulate, the defects and collision cascades interact and finally
overlap, producing an amorphous material that can brake into little pieces.
Break into little pieces. Or maybe something else. Totally different. Totally unexpected. Nobody knows. We've never been here before, this world of
irradiated metals. This is all new territory.
But that is what is happening to all solids that have a crystalline structure. All nuclear chain reactions occurring within any nuclear reactor have
been displacing atoms and screwing up the basic structures of all metals from the instant the reactions are initiated, including to the uranium and
everything else in the fuel. And neutron embrittlement not only makes things brittle, unstable and less transparent, the accumulated Wigner Energy
increases exponentially the energy released should there be an explosive reaction.
Plutonium appears to be less affected by the Wigner Effect than other metals as the self-irradiation process that constitutes it's total existence
seems to provide a certain amount of self-annealing and self-healing as well to it's crystalline structures. Built in protection from destroying
itself. Unfortunately other metals are not as adaptive. Nor is plutonium totally out of woods depending on it's phase.
Some Like It Hot
As mentioned, the only way to get the crystal lattice defects to return to a stable state is by heating to high temperatures. For graphite this
temperature needs to be greater than 250C, which means that the temperatures reached in an operating LWR reactor, between 300C and 350C, will reach
temperatures high enough to cause the graphite to anneal.
However, for zirconium and many other metals, the temperature needed for annealing is greater than the temperature a reactor operates at. This is
because they don't have the same type of bonds holding the lattice together as found in graphite. In order for the displaced atoms to move back into
the correct lattice positions, zirconium must be heated above 500C for Zircaloys, and above 560C for Zr-2 and 600C for Zr-4.
This means that all defects acquired through the years of housing a massive and constant neutron flux are still in the cladding of all spent fuel rods
made of zirconium. And more defects are happening all the time. For thousands of years. Or more.
The most notorious effect for zirconium is the fact that it becomes less transparent, and transparency is why zirconium was used in the first place,
to allow the neutrons to pass through freely. Zirconium has closely packed crystal structures, and it is easier for a neutron to slide by a lattice
that is closely packed. Until you kick it out of shape and it becomes elastically deformed. Then the expanded lattices take up more room blocking
The primary actinides found in spent fuel are the following; U-235, U-236, U-238, Pu-238, Pu-239, Pu-240, Pu-241, Pu-242, Np-237, Am-241, Am-242m,
Am-243, Cm-242 and Cm-244.
Of these uranium will always comprise the major bulk of the fuel. Uranium does not self-heal itself, like plutonium. In fact, uranium does not heal
itself well even when annealed at temperatures greater than needed for zirconium. Annealing defects occur, which include further swelling by as much
as 20%, with pores that form in the expanded material, weakening it.
Uranium specimens annealed up to 75 hours at temperatures between 650C and 750C in the beta phase were badly cracked and contained pores of a small
diameter uniformly distributed within the grains. A specimen annealed up to 16 hours at 822C decreased in density about 20 % and produced pores of
large diameter located along grain boundaries as well as pores of smaller diameter.
The reactor pressure vessel is in a similar state as zirconium, though the temperatures needed for annealing are slightly less than zirconium, usually
from 400C to 480C, depending on the type of reactor.
Wigner And The Nuclear Stockpile
It was a bit of a shock to learn that the actinides were affected by the Wigner Effect as well as the metals used for cladding of the fuel rods and
reactor parts. Unfortunately it didn't prepare me for an even bigger shock. While researching neutron embrittlement I came across a military document
that discussed the potential for embrittlement to affect the nuclear weapons stockpile. It froze me in place.
It hadn't occurred to me that the Wigner Effect and neutron embrittlement would also affect a nuclear weapons stockpile. But of course it would, and
in the same ways that it affects nuclear fuel rods and reactor vessels. It makes all solids in the bomb and barriers expand, become brittle, unstable,
and possessing greater stored energy than before.
The next question is how long will any of these metals like the high explosives detonator or tritium containers, survive housing with plutonium, and
what happens when they go south. Which is a million dollar question.....with no answer.
The scientific world doesn't have a clue what will happen. Not in the long term. Not in the mid term. And not in the short term. All they know is that
plutonium is the least affected. That's why the following paragraph's from a DOE report scared the hell out of me.
"Thus, crucial primary-stage components that were initially subject to concern have been shown through the SSP to be robust as they age. Indeed, there
is now consensus among specialists that the Pu pits in the US stockpile are stable over periods of at least 50–60 years, with the most recent
studies suggesting a far longer period".
The most stable thing in nuclear bombs is stable for 50-60 years, maybe longer, maybe not, and nuclear bombs are 30, 40, 50 years old
"Certain critics have expressed the view.....that it would be best to let the stockpile degrade and its stewards turn to other activities.
However....the worst option is to allow the stockpile to become unsafe or unreliable".
In other words, just like a nuclear power plant, without constant maintenance, nuclear weapons worldwide will become unsafe as they approach their age
of instability and...................
Concerning the second paragraph, one has to wonder why the thought of abandoning our nuclear stockpile would even be considered in the first place. If
maintenance is needed to keep the stockpile stable and safe, there is no question what should be done. Yet DOE has to think about it.
By the way, as stated, the stockpile report above is from DOE (US Department of Energy). That's one more way the military (DOD or Dept of Defense)
doesn't have to pay for something. We build the bombs, stockpile the bombs, maintain the bombs and dismantle the bombs, all on money that could be
used for research into solar cells, distributed power systems or some other life saving project the DOE claims to always be funding........but
doesn't. DOE is nothing more than a branch of the military and has more important things to do, like take care of fragile bombs that could destroy
life on this planet.
Next: Chapter Nineteen) The Day It Rained Yellow Fire In Kanto
edit on 24-4-2012 by zworld because: (no reason given)