Fleischmann Pons: What might have gone wrong

This is mostly a wild guess because I am not studying their work.  Instead, I'm speculating upon a few possibilities.  From what little I've read about their work, it looks like they may not have considered the possibility that the deuterons could be fusing with the palladium.  Secondly, the quality of the reactions may depend upon what isotopes were in the sample.  Thirdly, if they weren't looking for this, they may have been overlooking the evidence of this, as there should have been cadmium, if the fusions were taking place.

Let's look at the normal concentrations of palladium:

http://www.ncnr.nist.gov/resources/n-lengths/elements/pd.html

Over 50% of the palladium is the isotopes of 102 and 104 through 106.  Since a deuteron is of atomic mass approximately equal to 2, each fusion will move the atomic weight up by 2.  For example, a fusion of palladium 102 will yield silver 104, which can be seen as beta plus decaying below:

http://www.kcvs.ca/site/projects/physics_files/nucleus/decays.swf

 But this is only 1 percent of the palladium.  What about the rest?  It so happens that the rest of the chain does not proceed as well if you start with an isotope of greater mass.  Palladium 104 fused with deuterium yields the following:

slightly less energy from this beta plus decay

 Now, you are up to palladium 106, which is stable.   What happens if another fusion takes place? You will get mostly cadmium via beta minus decay, as follows:

This is still good, but cadmium doesn't like to cooperate any further, the chain stops here

We get no further benefit, as we can see from the isotopes of cadmium chart, no further beta decays are going to be available.  Cadmium 112, 114, and 116 just aren't going to be useful because they are stable, and the one isotope, 116 that isn't has a very long half life.

If we follow this chain, we get several good reactions, but it will have to stop with the production of cadmium.  However, this chain starts with an isotope that makes up only 1% of the total amount of palladium.  What happens if we start at some other isotope.  If we start at 104 and 106, we get a shorter version of this chain.

If we start with palladium 105, which makes up a significant portion of the sample, the reaction stops with the production of silver.  If palladium 105 is overrepresentative in the sample, the potential is reduced.  Likewise, if palladium 102 is underrepresentative, the potential is also reduced.

Palladium 110 doesn't do much good since it will end there at cadmium, as indicated above.  Very short chain.  That leaves palladium 108, which is shown below:

Back to cadmium, it the chain will end here

In summary, 102, 104, 106, and 108 all work, but you should start with 102, which is the most rare isotope.  I think that is the whole point.  The other chains are too short and most of the palladium isn't all that useful.  If you just start with 102, you will generate the rest of the chain in sequence.  Most of it isn't very good.  You can use it, but not for as much energy production as you may have wished for.

You could remove palladium 105 and 110 altogether since they don't help.  This makes up almost a third of the palladium in a normal sample.   Over 1/2 of the palladium gives short chains.