[ RadSafe ] Nuclear battery could turn hazardous waste into lasting clean energy

[Jaro Franta]

Not so sure it's such a good idea.... seems more like pure hype to me.

At about 1.3 tonnes of synthetic diamonds per Watt of electricity, who in
their right mind would ever consider actually building such a ridiculous
battery ?

Some calculations:

A Russian report gives approximately 8% energy conversion efficiency.
http://www.naun.org/main/NAUN/circuitssystemssignal/2015/b182005-012.pdf 

Average Carbon-14 decay energy is 50keV (1eV = 1.6E-19 joules). 
Multiplying by 6.02E+23 and dividing by 14 gives 344MJ/g total decay energy.
Half of that energy, 172MJ/g, is released in a 5730-year half-life, so the
power per gram is 172E+6 J / (5730 x 365 x 24 x 60 x60 seconds) = 0.95 mW/g

With an 8% energy conversion efficiency, that comes to about 0.076 mW/g of
pure C14.

If the graphite from decommissioned nuclear reactors contains 1% C14 (ie.
all natural C13 gets converted to C14), then without isotopic separation,
the expected electric output of the synthetic diamonds would be 0.00076 mW
per gram.
Or about 1.3 tonnes of synthetic diamonds per Watt of electricity.

How much energy does it take to produce a tonne of synthetic diamonds ?

-------------------------------

PS.  I’m still trying to get at the C14 concentration in graphite moderator
blocks.

Pure C14 has a specific activity of 4.5 Ci/g or 0.167 TBq/g or 167,000
TBq/tonne.

If we take the Magnox graphite C14 production figure of 10.8 TBq/GWe-y and
combine that with typical operating parameters (about 6.9 GWe-y lifetime) we
get:
10.8 TBq/GWe-y x 6.9 GWe-y = 74 TBq of C14 total per Magnox reactor.

With an inventory of 3,500 tons of graphite (3,175 metric tonnes), that
comes to an average C14 activity of about 0.025 TBq/tonne of moderator.
Therefore the average C14 concentration is:
0.025 TBq/tonne of moderator ÷ 167,000 TBq/tonne pure C14 = 1.5E-7 or
0.000015%

That’s extremely low !
Ten thousand times less than just assuming that all C13 (1.1%) gets
converted to C14.
Did I make a mistake somewhere in the algebra ?

 Jaro
^^^^^^^^^^^^^^^^^^^^^^^^^




-----Original Message-----
From: radsafe-bounces at health.phys.iit.edu
[mailto:radsafe-bounces at health.phys.iit.edu] On Behalf Of Ted de Castro
Sent: Wednesday, November 30, 2016 2:22 PM
To: The International Radiation Protection (Health Physics) Mailing List
Subject: [ RadSafe ] Nuclear battery could turn hazardous waste into lasting
clean energy

Now here's a good idea!!!

http://www.digitaltrends.com/cool-tech/diamond-battery-clean-energy/


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