The Resources of the Earth - Thanatia: The Destiny of the Earth's Mineral Resources - page 138

Fission nuclear energy is produced during the controlled transformation of suit-
able radioactive isotopes, when neutrons are fired into the nucleus. This process
leaves the atoms unstable and subject to spontaneous disintegration. The crucial
raw material for fission energy is uranium as it is the only naturally occurring fis-
sionable atom (when mined it contains 0.71% of 235 U). Thorium, beryllium, lithium
and zirconium are other low-demand raw materials with potential or specific uses in
nuclear power production (Darnley, 1987). When 235 U undergoes fission, it releases
heat and forms new elements whilst ejecting some neutrons from its nucleus. These
neutrons are then used to induce more 235 U to fission. According to Skinner (1986),
once separated 235 U from 238 U (an energy intensive process), the disintegration of a
single atom releases 3:210 11 J 5 . Eq. (6.2) shows a representative fission process
of 235 U.

1

0 n + 235 92 U ! 137 37 Cs + 9 37 Rb + 3n + 3:2 10 11 J

(6.2)

Estimated uranium resources amount to about 13 Mt according to Grubler et al.
(1998) and 14.8 Mt according to theOECD (2004), which represent an exergy reser-
voir of about 23,800 and 27,100 Gtoe, respectively. Given the current state of
technology, which makes use of only 0.7% of the natural fuel in a “once-through”
fuel cycle, the reserves may last only a few hundred years (174 Gtoe). With fast
spectrum reactors operated in a “closed” fuel cycle by reprocessing the spent fuel and
extracting the unspent uranium and plutonium produced, the reserves of natural
uranium may exceed 5,200 Gtoe (Table 6.8). And, if advanced breeder reactors are
in the future to be designed to e ciently utilise recycled or depleted uranium and
all actinides, then the reserves of natural uranium may extend to several thousand
years at current consumption levels (OECD, 2006).
Additionally, Hermann (2006), estimated the exergy reserves of thorium as
around 7,500 Gtoe and of uranium in seawater at around 8,350 Ttoe.
At the end of 2010, 5% of the world's primary energy consumption was derived
from nuclear power plants (see Fig. 6.4), which amounted to some 626.2 Mtoe. In
France, about 40% of the electrical power comes from nuclear plants and in other
European countries and Japan, the percentage is high too. IPCC (2007b) forecasted
that some 279 - 740 GWe would be produced in 2030 should the proposed new plants
and the decommissioning of old ones be considered. However, energy strategies
regarding nuclear power have changed since the 2011 Fukushima accident 6 . In
response to its aftermath, the International Atomic Energy Agency (IAEA) reduced
its low projection scenario of nuclear based generation by 16%. A more moderate
drop of 8% was assigned for the high projection.

5 Since one gram of 235 U contains 2:56 10 21 atoms, fission of a gram of uranium produces
8:19 10 10 J (equivalent to the energy released when 2.7 metric tons of coal are burned).
6 Following a major earthquake, a 15-metre tsunami disabled the power supply and cooling of
three Fukushima Daiichi reactors, melting the cores. Over 100,000 people had to be evacuated
from their homes due to the detection of highly radioactive releases.