From: "S. M. Halloran" <mitch@duzen.com.tr>
Date: Tue, 7 Oct 1997 15:25:02 +0800
To: cypherpunks@cyberpass.net
Subject: Re: russia_1.html
In-Reply-To: <199710070641.IAA02251@ankara.duzen.com.tr>
Message-ID: <199710070709.JAA02293@ankara.duzen.com.tr>
MIME-Version: 1.0
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> I think this comment is in error.  Plutonium has a half life on the
> order of 250,000 years, so very little decay products would build up
> in 6 years. The tritium used in thermonuclear weapons has a much
> shorter half life, and would need to be replaced about that often.


Since radioactive decay is first-order, the following equation 
applies:

      N = N  exp(-kt)
           0

where N=amount of material at time 't'; N = amount of material at time
t; k=decay rate constant; t=time of interest.

The decay rate constant (k) for first-order decay processes can be
expressed as k = ln(2)/half-life.

Hence the equation can be expressed as follows:

    N / N  = exp(-[ln(2)/half-life]*t)
         0

N / N  will express the amount of substance remaining as a percentage 
     0
of the original.

Plugging in the numbers:

      exp(-[ln(2)/250,000y]*6y) = 99.998%

Hence, ca. 0.002% (actually less than that) of the material has 
decayed.  It may be the case that even this minute amount of 
"impurity" could poison something like weapons-grade material, but I
am not a radioactive materials expert.

Mitch Halloran
Research Biochemist/C programmer/Sequioa's (dob 12-20-95) daddy
Duzen Laboratories Group
mitch@duzen.com.tr