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Townhall...
Nuclear Fears and
Facts
By Paul Driessen
The ground hadn’t stopped shaking. Tsunami waters had not receded. And
yet coverage of this awful natural disaster – a scene of almost
unfathomable devastation and death – was already giving way to
single-minded focus on radiation exposure and meltdowns.
Addressing justifiable concerns is essential, to allay fears and
refocus attention on finding the missing, burying the dead, helping
450,000 displaced people, and rebuilding ravaged communities.
Like a third of nuclear plants in American service today, providing 20%
of all US electricity, the 40-year-old Fukushima Daiichi plant is a
“boiling water reactor.” Uranium in fuel rods generates heat to turn
water into steam that drives turbines, which power generators.
Though not designed or built according to current standards, the
Japanese plant had many upgrades and enhancements over the years. For
the most part, they worked.
Originally designed to withstand a Richter scale magnitude 8 quake,
Fukushima was struck by a magnitude 9 earthquake. The tremor carried
ten times the power and released 32 times more energy than an 8, and
rattled the plant with more “peak ground acceleration” than it was
designed for.
Fukushima withstood all that. But then a 45-foot tsunami roared over
the plant’s 25-foot-high seawall, took out its backup diesel generators
and knocked out electricity for miles. After backup batteries died,
fuel rods and spent fuel began to overheat and cause explosions and
radiation leaks that crews are still battling, mostly with increasing
success.
While 28,000 people are dead or missing from the earthquake and
tsunami, nuclear fuel damage appears to be short of a meltdown.
Radiation levels are being addressed though distribution of potassium
iodide tablets, evacuations for several miles around the plant, food
supply testing, and other measures.
That is reassuring. But better reactor designs are clearly needed, and
are under development. High temperature gas reactors employ helium,
rather than water, as a coolant. One version, the pebble bed modular
reactor, replaces fuel rods with 2-inch-diameter graphite balls
containing uranium granules. The South African version has been
designed, and sub-assemblies and fuel balls manufactured and tested
successfully, but economics have put the project on hold. A Chinese
pebble bed design is under construction.
Another reactor type could be powered by molten fluoride salt
containing thorium. This fuel is more plentiful and more easily handled
than uranium, and produces more energy per volume of fuel.
TerraPower’s “traveling wave” reactor uses waste uranium as a fuel;
Bill Gates and other investors say commercial operations are 15 years
away. A new nickel-hydrogen “cold fusion” reactor, developed by two
Italian scientists, is also attracting attention.
Until these futuristic systems arrive on the scene, nuclear plants
already in the concept, design or construction stage will be better and
safer than those that already help power America. However, existing
reactors and those under construction are safe.
Twenty US plants now undergoing licensing or site preparation are all
Generation III. They feature more “inherently safe design” elements and
more “passive” safety features (such as auto response and gravity
cooling systems) that rely less on human interaction with complex
control systems.
The 104 commercial reactors already operating in the United States are
all Generation II, enhanced over the years in response to new safety
concepts and equipment, newly identified threats (such as terrorism
after 9/11), and problems like Three Mile Island.
Gen II power plants consist of boiling or pressure water reactors
surrounded by a steel wall, steel-reinforced concrete casing, and
steel-reinforced concrete building. Nuclear engineers say US-based
plants are designed, engineered and built to handle expected worst-case
disasters like earthquakes, tornadoes, hurricanes and floods – and
analyzed for possible effects of terrorism – with multiple backup
systems.
These efforts are supplemented during and after construction by
exhaustive design reviews and modifications, and ongoing upgrades or
replacement of equipment, instruments, controls and power lines.
Further enhancements to equipment, training and procedures occur during
the relicensing process and in response to natural disasters, operator
errors, equipment failures, terrorist acts, and the discovery of design
or manufacturing defects, in the US and around the world.
The system is designed to provide defense in depth, have appropriate
equipment and procedures in place, and establish a “culture of safety.”
Operators are trained continually to execute normal and emergency
procedures, and emergency preparedness is drilled every two years with
industry, state and local officials, under oversight by the Nuclear
Regulatory Commission and Federal Emergency Management Agency.
Fukushima apparently was insufficiently prepared for a disaster of the
magnitude it experienced, in this major Pacific Ring of Fire earthquake
and tsunami zone. The failure of diesel generators is already driving
another look at passive safety systems; the hydrogen explosions a
reassessment of ways to vent pressure buildups to special containment
vessels; the overheating spent fuel rods new demands for reprocessing
or safe offsite waste repositories, like Yucca Mountain.
The industry, NRC, FEMA, Congress, and state agencies are all
reassessing and re-verifying the ability of nuclear plants, plans,
equipment and personnel to handle events of Fukushima’s magnitude.
Lessons from that near-disaster will be evaluated and employed
worldwide.
Meanwhile, development of Generation III and IV nuclear reactors
continues globally.
There can be no guarantees, no absolute fail-safe system. But those
entrusted with nuclear power plant electricity generation and safety
can and must come as close as possible.
Meanwhile, the rest of us must focus on helping northeastern Honshu
recover – and offering thanks and prayers for the heroic workers who
exposed themselves to dangerous radiation levels, to prevent a real
disaster.
Read the article at Townhall
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