Eric and Jones--

The slide of atom % and mass % of the fuel before is pretty clear.  It 
considers a significant fraction of the fuel before and after the reaction and 
includes many, but not all elements, (fore example Li) that were observed.  It 
is based on laser atomic-emission  activation spectrometry (IGIC-RAS).  

My comment is only addressing the issue of whether Zn-64 was mistaken for Ni-64 
which Jones raised a couple days back. 

The link is here:  view

Bob Cook

From: Eric Walker 
Sent: Friday, March 25, 2016 11:12 PM
To: vortex-l@eskimo.com 
Subject: Re: [Vo]:Re: Kamacite and natural fractionation of heavy nickel

On Fri, Mar 25, 2016 at 10:16 PM, Bob Cook <frobertc...@hotmail.com> wrote:


  If you believe slide 13 of the AP report, there was very little Zn in the 
fuel to start with and even less after reaction.  Ni amounted  to 60 weight % 
to start and Zn was reported to be .0135 %.  There was not much Zn-64 in any 
case. 

I've found the calculation a little hard to work through, lacking knowledge of 
and information about how the percentages in the Parkhomov slides are derived, 
but consider that the slides allege that 4.4 percent of the starting nickel was 
64Ni.  I assume these percentages are derived from the ratio of counts at the 
m=64 mass peak to counts at all mass peaks for naturally occurring isotopes of 
nickel (m=58,59,60,61,62,64).  That is to say, I think we're dealing atomic 
percentage rather than percentage by weight.

Rather than try to disentangle the original counts for different mass peaks 
from this information, I'll note that the natural abundance of 64Ni is 0.9%, in 
contrast to Parkhomov's starting NA of 4.4%, and just take a shortcut and 
assume for the sake of argument that ~ 0.9/4.4% = 20% of the counts at m=64 
were actually 64Ni and the remaining 80% of the alleged 64Ni were actually 
64Zn, giving ~ 0.8 * 4.4%  = 3.5% 64Zn as a fraction of the nickel present.  
Since the percentage of nickel by atom was 36.4% (from slide 13), that gives 
0.035 * 36.4% = 1.2% 64Zn in terms of 100% of atoms.  Because the natural 
abundance of 64Zn is 48%, that implies that there should have been 1.2%/0.48 = 
2.5% zinc atoms per 100% of atoms.  The reported value was 0.7%, which is off 
by a factor of 4, but not 40 or 400.

So unless I've made a big error, we're in the right ballpark.  If there was a 
lot experimental uncertainty in the reported amounts, e.g., because the fuel 
was heterogeneous or the procedure was not very accurate, then being off by a 
factor of 4 is not difficult to imagine.

Eric

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