### Using uranium from rivers

The uranium in the oceans is being topped up by rivers, which deliver
uranium at a rate of 32 000 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.

### What about costs?

As usual in this book, my main calculations have paid little attention to
economics. However, since the potential contribution of ocean-uranium-
based power is one of the biggest in our “sustainable” production list, it
seems appropriate to discuss whether this uranium-power figure is at all
economically plausible.

Japanese researchers have found a technique for extracting uranium
from seawater at a cost of \$100–300 per kilogram of uranium, in compar-
ison with a current cost of about \$20/kg for uranium from ore. Because
uranium contains so much more energy per ton than traditional fuels, this
5-fold or 15-fold increase in the cost of uranium would have little effect on
the cost of nuclear power: nuclear power’s price is dominated by the cost
of power-station construction and decommissioning, not by the cost of the
fuel. Even a price of \$300/kg would increase the cost of nuclear energy
by only about 0.3 p per kWh. The expense of uranium extraction could
be reduced by combining it with another use of seawater – for example,
power-station cooling.

We’re not home yet: does the Japanese technique scale up? What is
the energy cost of processing all the seawater? In the Japanese experiment,
three cages full of adsorbent uranium-attracting material weighing
350 kg collected “more than 1 kg of yellow cake in 240 days;” this figure
corresponds to about 1.6 kg per year. The cages had a cross-sectional area
of 48 m2. To power a once-through 1 GW nuclear power station, we need
160 000 kg per year, which is a production rate 100 000 times greater than
the Japanese experiment’s. If we simply scaled up the Japanese technique,
which accumulated uranium passively from the sea, a power of 1 GW
would thus need cages having a collecting area of 4.8 km2 and containing
a weight of 350 000 tons of adsorbent material – more than the weight of
the steel in the reactor itself. To put these large numbers in human terms,
if uranium were delivering, say, 22 kWh per day per person, each 1 GW
reactor would be shared between 1 million people, each of whom needs
0.16 kg of uranium per year. So each person would require one tenth of the
Japanese experimental facility, with a weight of 35 kg per person, and an
area of 5 m2 per person. The proposal that such uranium-extraction facilities
should be created is thus similar in scale to proposals such as “every
person should have 10 m2 of solar panels” and “every person should have a

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