Re: D2O (was C14 Decay rates)

[Larry Cartwright <exit60@CABLESPEED.COM>]

Brian Whatcott wrote:
> More nit-picking:
>   heavy water is found at concs of 1:7000 in domestic water.
> (It has a higher boiling point than H2O, so I imagine specifying distilled
> tap water would somewhat enrich it.)
> 1 kg of tap water would include 1/7 g of D2O then.
> That's about 143 mg. If the electrolysis sacrificed 3% of the D2O along
> with 97% of the H2O, one would have about 127 mg D20 remaining
> per kg domestic water, not 35 mg when 99.95% purity is obtained.

The 1:7000 figure is the natural ratio of deuterium/protium, not
D2O/H2O.  There are two forms of H-2 heavy water, D2O and DOH (singly
deuterated water, one particle each of deuterium, oxygen and protium).
The natural occurrence of *both* forms is between 1:6700 - 1:7100
(140-150 ppm).  Less than 1/4 of the total heavy water is D2O.  In the
production of D2O heavy water, both the H2O and DOH are discarded.  The
maxiumum D2O yield is 30-35 ppm.

> Diffusion separation of Uranium isotopes is now superceded by
> chemical means, which according to some rumblings, is ridiculously easy.

Electrolytic separation of heavy water has also been superceded by
chemical processes, using H2S or NH3 and finishing with distillation.
The rate of production is about 3 ppm, 3 ml of D2O for every 1000 liters
of water processed.

It really bothers me that production of U-235 has become easier.  The
difficulty in obtaining fissionable material has been an important
factor in keeping nuclear weapons out of the hands of small-time thugs
for half a century.  Until now, only big-time thugs have been able to
afford the technology.

Best wishes,

Larry

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Larry Cartwright   <exit60@cablespeed.com>
Retired (June 2001) Physics Teacher
Charlotte MI 48813 USA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~