Page 583 - Environment: The Science Behind the Stories

concern that radioactive material could be stolen from plants
and used in terrorist attacks. This possibility has been espe-
cially worrisome in the cash-strapped nations of the former
Soviet Union, where hundreds of former nuclear sites have
gone without adequate security for years. Finally, there is the
ever-present concern that more nations may develop nuclear
weapons.
To address concerns about stolen fuel and to reduce
the world’s nuclear weapons stockpiles, the United States
and Russia embarked on a remarkably successful program
called Megatons to Megawatts. In this cooperative inter-
national agreement, the United States has been buying up
weapons-grade uranium and plutonium from Russia, letting
Russia process it into lower-enriched fuel, and diverting it
to peaceful use in power generation. In recent years, up to
10% of America’s electricity has been generated from fuel (a) Wet storage
recycled from Russian warheads that used to be atop mis-
siles pointed at American cities! In 2013 it is expected that
the last of 500 metric tons of highly enriched uranium will
be processed and transferred, after which Russia and the
United States may negotiate some sort of continuation of the
program.

Waste disposal remains a challenge

Even if nuclear power generation could be made completely
safe, and even if we could recycle all weapons-grade fuel
into fuel for power plants, we still would be left with the
conundrum of what to do with spent fuel rods and other
radioactive waste. Recall that fission utilizes 235 U as fuel,
238
238
leaving as waste the 97% of uranium that is U. This U,
as well as all irradiated material and equipment that is no
longer being used, must be disposed of in a location from (b) Dry storage
which radiation will not escape. Because the half-lives FIGURE 20.11 Nuclear waste is stored at nuclear power
of uranium, plutonium, and many other radioisotopes are plants, because no central repository yet exists. Spent fuel
far longer than multiple human lifetimes, this waste will rods are kept in “wet storage” in pools of water (a), which keep
continue emitting radiation for thousands of years. Thus, them cool and reduce radiation release, or in “dry storage” (b) in
radioactive waste must be placed in unusually stable and thick-walled casks layered with lead, concrete, and steel.
secure locations where radioactivity will not harm future
generations.
Currently, nuclear waste from power generation is being conducted 20 years of research looking for a suitable loca-
held in temporary storage at nuclear power plants across the tion, and in 2009 selected the Forsmark power plant site as
world. Spent fuel rods are sunken in pools of cooling water its single disposal location. If the site is approved by govern-
to minimize radiation leakage (FIGURE 20.11a). However, most ment agencies and constructed as planned, spent fuel rods
U.S. plants have no room left for this type of storage, so they and other high-level waste will be systematically buried in
are now storing waste in thick casks of steel, lead, and concrete canisters about 500 m (1650 ft) underground within stable
(FIGURE 20.11b). In total, U.S. power plants are storing nearly bedrock.
70,000 metric tons of high-level radioactive waste—enough In the United States, the multiyear search homed in
to fill a football field to the depth of 7 m (21 ft)—as well as on Yucca Mountain, a remote site in the desert of southern
much more low-level radioactive waste. This waste is held at Nevada, 160 km (100 mi) from Las Vegas (FIGURE 20.13a).
more than 120 sites spread across 39 states (FIGURE 20.12). A Choice of this site followed extensive study by govern-
2005 report from the National Academy of Sciences judged ment scientists (FIGURE 20.13b), and $13 billion was spent on
that most of these sites were vulnerable to terrorist attacks. its development, although most Nevadans were not happy
Over 161 million U.S. citizens live within 125 km (75 mi) of about the choice. In 2010, as the site was awaiting approval
temporarily stored waste. from the Nuclear Regulatory Commission, President
Because storing waste at many dispersed sites creates a Barack Obama’s administration ended support for the pro-
large number of potential hazards, nuclear waste managers ject. Ironically this came just days after Obama had urged
would prefer to send all waste to a central repository that can expanding nuclear power in his State of the Union address.
582 be heavily guarded. In Sweden, that nation’s nuclear industry Most political observers agree that the opposition of Senate

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