Energy and Human Ambitions on a Finite Planet, 2021a

15 Nuclear <strong>Energy</strong> 263
water, food, <strong>and</strong> air. In short, nuclear fission carries many perils on a
number of fronts.
15.4.7 Nuclear Safety
A properly operating nuclear facility actually emits less radioactivity than
does a traditional coal-fired power plant! As is true for many materials
mined from the ground, coal contains some small amount of radioactive
elements found in the earth’s crust: principally thorium, uranium, <strong>and</strong>
potassium. Lacking any shielding or protection, the exhaust from a coal
plant distributes these products into the atmosphere. Nuclear plants,
by contrast, have no exhaust, 52 <strong>and</strong> carefully control the exposure to
radioactivity.
However, things can go wrong. The U.S. had a scare in 1979 when a
six-month-old nuclear plant at Three Mile Isl<strong>and</strong> in Pennsylvania (Figure
15.21) suffered a loss-of-cooling incident that resulted in severe damage
to (meltdown of) the core. But the containment vessel held <strong>and</strong> no
significant radioactivity was released to the environment. Workers at
the plant received a dose equivalent to an extra 100 days of natural 53
exposure. So we dodged a bullet.
Chernobyl was not so lucky in April 1986 when an ill-conceived test
went sideways <strong>and</strong> resulted in an actual explosion of the core. This
scenario was previously thought to be impossible, but it was a steam
explosion, not a nuclear blast—so more like a “dirty bomb” that scattered
radioactive material across the region. Thirty-one people died in the
immediate aftermath, <strong>and</strong> about 200 people got acute radiation sickness.
It is estimated that in the long term, 25,000 to 50,000 additional cancer
cases will result, but this number is controversial <strong>and</strong> it is hard to tease
Chernobyl-caused cancer/deaths apart from the much larger number of
background cancer cases. The town of Chernobyl is still ab<strong>and</strong>oned <strong>and</strong>
only recently has begun to allow strictly limited incursions.
The most recent major accident was the Fukushima Daiichi plant in
Japan following the Sendai earthquake in March 2011, resulting in the
evacuation of 200,000 people <strong>and</strong> agricultural loss. The earthquake
caused the three operating reactors to shut down (safely), while dieselfueled
generators ran to power pumps maintaining cooling flow over
the hot fuel rods. The core of a reactor is still very hot after fission stops
<strong>and</strong> continues to generate heat as daughter nuclei decay, so cooling flow
must be maintained or the core can melt. The ensuing tsunami 54 ruined
the plan to keep the cores cool, as the generator rooms flooded, causing
the cooling flow to fail. The cores of all three reactors melted down
<strong>and</strong> hydrogen gas explosions created a major release of radioactivity.
Perhaps in contrast to the Chernobyl plant, Fukushima was designed by
General Electric <strong>and</strong> operated by a well-educated high-tech society. No
one is exempt from risk when it comes to nuclear reactors.
52: Note that cooling towers often have a
plume of water vapor above them, but this
is the result of evaporative cooling, <strong>and</strong> not
exhaust in the usual sense.
53: We are unavoidably exposed to radiation
in our daily lives from air, water, food,
Earth, <strong>and</strong> the cosmos.
Figure 15.21: Three Mile Isl<strong>and</strong> nuclear
plant in Pennsylvania. The two reactor cores
are in the foreground of the larger cooling
towers behind. Source: U.S. DoE.
54: . . . within 10 minutes of the earthquake
© 2021 T. W. Murphy, Jr.; Creative Commons Attribution-NonCommercial 4.0 International Lic.;
Freely available at: https://escholarship.org/uc/energy_ambitions.