Energy Solutions to Air Pollution and Global Warming - Air Pollution and Global Warming: History, Science, and Solutions - page 312

is no guarantee that the reactors will be designed, built,
and operated correctly or that a natural disaster or act of
terrorism, such as an airplane flown into a reactor, will
not cause them to fail, resulting in a major disaster.
Through 2011, about 1.5 percent of all nuclear reac-
tors in history had a partial or significant core melt-
down. On March 11, 2011, an earthquake measuring
9.0 on the Richter scale, and the subsequent tsunami
that knocked out backup power to a cooling system,
caused six nuclear reactors at the Fukushima 1 Dai-
ichi plant in northeastern Japan to shut down. Three
reactors experienced a significant meltdown of nuclear
fuel rods and multiple explosions of hydrogen gas that
formed during efforts to cool the rods with seawater.
Uranium fuel rods in a fourth reactor also lost their
cooling. As a result cesium-137, iodine-131, and other
radioactive particles and gases were released into the air.
Locally, tens of thousands of people were exposed to
the radiation, and 170,000 to 200,000 people were evac-
uated from their homes. The radiation release created a
dead zone around the reactors that may not be safe to
inhabit for decades to centuries. The radiation also poi-
soned the water and food supplies in and around Tokyo.
The radiation plume from the plant spread worldwide
within a week. Concentrations in Japan within 100 km
of the plant were very high, whereas those across the
Pacific Ocean were more modest. The lesson from this
and similar events is that, even if the risks of catas-
trophe from nuclear power are small, they are not
zero. Catastrophic risks with wind and solar power are
zero.
Fourth, conventional nuclear fission reactors ,
which are nuclear reactors in which only about 1 per-
cent of the uranium in the nuclear fuel is used and the
rest disposed of, produce radioactive waste that must
be stored for up to 200,000 years. This gives rise to con-
cerns about how to prevent leakage of the waste for such
avast period and the long-term costs of storage. Due
to their inefficient use of uranium, conventional nuclear
reactors could exhaust uranium reserves in roughly a
century if a large-scale nuclear program were under-
taken.
Alternate types of reactors (e.g., breeder reactors),
nuclear fuels (e.g., thorium), and processes (e.g., fusion)
have been proposed. Breeder reactors reuse spent
nuclear fuel, thereby consuming a much higher percent-
age of uranium, producing less waste, and resulting in
lower uranium requirements than conventional reactors.
However, breeder reactors produce nuclear material that
can be reprocessed more readily into nuclear weapons
than can material from conventional reactors.

Thorium , like uranium, can be used to produce
nuclear fuel in breeder reactors. The advantage of tho-
rium is that it produces less long-lived radioactive waste
than does uranium. Its products are also more diffi-
cult to convert into nuclear weapons material. How-
ever, thorium still produces 232 U, which was used in
one nuclear bomb core produced during the Operation
Teapot bomb tests in 1955. Thus, thorium is not free of
nuclear weapons proliferation risk.
Nuclear fusion of light atomic nuclei (e.g., protium,
deuterium, or tritium; Section 1.1.1) could theoretically
supply power indefinitely without long-lived radioac-
tive waste because the products are isotopes of helium.
However, there is little prospect for fusion to be com-
mercially available for at least 50 to 100 years, if ever.

13.1.2. Why Not Coal with Carbon Capture?
Carbon capture and sequestration (CCS) is the diver-
sion of CO 2 (g) from a point emission source, such as a
coal-fired power plant exhaust stack, to an underground
geological formation (e.g., saline aquifer, depleted oil
and gas field, or unminable coal seam). Geological for-
mations worldwide may theoretically store up to 2,000
Gt-CO 2 (g), which compares with a fossil fuel emission
rate today of 30 Gt-CO 2 (g) yr − 1 .Todate, CO 2 (g)

has been diverted underground following its separation
from mined natural gas in several operations and from
gasified coal in one case. However, no large power plant
currently captures CO 2 (g). Several options of combin-
ing fossil fuel combustion for electricity generation with
CCS technologies have been considered. In a standard
model, CCS equipment is added to an existing or new
coal-fired power plant. CO 2 (g) is then separated from
other gases and injected underground after coal com-
bustion. The remaining gases are emitted into the air.
Other CCS methods include injection into the deep
ocean and production of carbonate minerals. Ocean
storage, however, results in ocean acidification. Dis-
solved CO 2 (g) in the deep ocean eventually equilibrates
with that in the surface ocean, reducing ocean pH and
simultaneously supersaturating the surface ocean with
CO 2 (g), forcing some of it into the air.
Producing carbonate minerals has a long history.
Joseph Black (Section 1.2.2.6) named carbon dioxide
fixed air because it fixed to quicklime [(CaO(s)] to
form CaCO 3 (s). However, the natural process is slow
and requires massive amounts of quicklime for large-
scale CO 2 (g) reduction. The process can be hastened by
increasing temperature and pressure, but this requires
additional energy.

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