3.6. Nuclear? http://www.ck12.org
4 .5 billion tons per planet
162 tons uranium per GW-year
=28 million GW-years per planet.How fast could uranium be extracted from the oceans? The oceans circulate slowly: half of the water is in the Pacific
Ocean, and deep Pacific waters circulate to the surface on the great ocean conveyor only every 1600 years. Let’s
imagine that 10% of the uranium is extracted over such a 1600-year period. That’s an extraction rate of 280000 tons
per year. In once-through reactors, this would deliver power at a rate of
2 .8 million GW-years
1600 years= 1750 GW,
which, shared between 6 billion people, is 7 kWh per day per person. (There’s currently 369 GW of nuclear reactors,
so this figure corresponds to a 4-fold increase in nuclear power over today’s levels.) I conclude that ocean extraction
of uranium would turn today’s once-through reactors into a “sustainable” option – assuming that the uranium reactors
can cover the energy cost of the ocean extraction process.
Figure 24.6: “Sustainable” power from uranium. For comparison, world nuclear power production today is 1.2
kWh/d per person. British nuclear power production used to be 4 kWh/d per person and is declining.
Fast breeder reactors, using uranium from the oceans
If fast reactors are 60 times more efficient, the same extraction of ocean uranium could deliver 420 kWh per day per
person. At last, a sustainable figure that beats current consumption! – but only with the joint help of two technologies
that are respectively scarcely-developed and unfashionable: ocean extraction of uranium, and fast breeder reactors.
Using uranium from rivers
The uranium in the oceans is being topped up by rivers, which deliver uranium at a rate of 32000 tons per year. If
10% of this influx were captured, it would provide enough fuel for 20 GW of once-through reactors, or 1200 GW of
fast breeder reactors. The fast breeder reactors would deliver 5 kWh per day per person.
All these numbers are summarized in figure 24.6.