Nuclear
Safety After Fukushima
By Christopher
Stephens
This article was
first published in The
Wall Street Journal's Opinion Column on March 21, 2011.
Even with events at
Japan's Fukushima Daiichi nuclear power complex still in a state of flux,
attention is shifting from containment to assessment. The 9.0 magnitude
earthquake, hundreds of aftershocks and ensuing tsunami were historic.
But they can hardly be called unforeseeable, and therein lies the nub of
the critical questions this incident will raise for regulators
everywhere: To what extent should nuclear safety regulation take account
of all foreseeable contingencies, and should new technologies be required
to apply to pre-existing facilities that were built to the standard of
the industry at the time of construction?
The six-reactor
Fukushima Daiichi facility was commissioned in 1971 and—by
design—successfully withstood the March 11 earthquake and its
aftershocks. But the tsunami topped the facility's sea wall, knocking out
the back-up diesel generator and forcing the pump cooling systems and
pressure ventilators to rely on batteries until mobile generators could
be delivered to the site. Water also flooded the basement where switching
equipment connected the pumping equipment, impeding repairs.
The result was
overheating that caused pressure to build to over two times the designed
limitations and led to explosions at three of the reactors. The outer
buildings were designed to contain the reactor and to withstand severe
weather conditions, but not hydrogen explosions. Radiation leakages
resulted, causing widespread concerns about threats to health and the
environment.
Such a chain of
events, however extraordinary, cannot be said to be unforeseeable. Japan's
infrastructure and regulatory framework have anticipated earthquakes for
150 years; power outages, tsunamis and widespread demands that strain
response efforts are all predictable consequences of earthquake risk.
Indeed, engineers
have already designed solutions to mitigate the risks that materialized
at Fukushima. Today's third-generation nuclear reactors anticipate the
possibility of failed cooling systems and hydrogen pressure build-ups.
The Westinghouse AP1000 reactor has a series of passive cooling systems
that operate without external or diesel-generated power or activation by
its operators. It also has recombiners that prevent hydrogen explosions.
This design has been
officially adopted in China for all inland nuclear projects where
earthquake risks are more prevalent than on its coasts. Areva's EPR
reactor under construction in Finland, France and China has four
independent emergency passive cooling systems and extra core containment
areas around the reactor. And Mitsubishi's new APWR has passive and
active redundant cooling systems.
So why weren't these
technologies installed at Fukushima? Nuclear safety regulators around the
world assess risks associated with nuclear power facilities on the basis
of the technology to be deployed and the location and range of events
that potentially could threaten the safety or control of the facility.
Even after construction, regulators are given wide discretion to impose
additional requirements on the equipment, systems and procedures used at
a given facility.
The problem is how
to decide when to require plant operators to implement costly refits of
new technology on older plants—and this is where Japan's regulators could
ultimately come in for some justifiable scrutiny. This is a question of
both engineering and cost-benefit analysis. While certain modular
equipment and control systems in nuclear plants can be upgraded, integral
parts of the reactor chamber or housing cannot be easily removed,
disposed of and replaced due to the presence of radioactivity.
This means that in
some cases the choice may not be whether or not to upgrade, but whether
to shut down entirely. Given those options, operators and regulators are
inclined to maintain the status quo instead of requiring the application
to old facilities of newer systems to more effectively address risks that
can seem quite remote. Fukushima may cause a rethink of this approach not
only in Japan but around the world.
Japan's experience
also suggests regulators and emergency planners need to think more realistically
about the circumstances under which an emergency is likely to occur. Most
nuclear safety regulations are based on a scenario where a singular
disaster occurs at a specific facility—akin to Chernobyl or Three Mile
Island, incidents that arose due to circumstances within the plants
themselves or external events affecting their immediate vicinity.
That approach to
planning can leave officials unprepared for what has happened at
Fukushima: a nuclear incident as part of a much larger disaster. In the
aftermath of the Sendai earthquake, response teams and resources were
required to cover an area of 35,000 square miles, in which two million
people were without power, water or food, and roads, airports and other
infrastructure were severely damaged. More far-sighted planning would
have anticipated the limitations on emergency services in such
circumstances.
Finally, regulators
need to account for the societies and particular cultures they cover.
Japan's great wealth, technological advancement and quality
infrastructure made it remarkably resistant to the ravages of a great
earthquake and horrific tsunami. And the high levels of education and the
renowned discipline of its people certainly helped it avoid apocalyptic
consequences. While this hasn't averted the problem at Fukushima, it does
mean the country was better equipped to deal with such an event than
others might have been.
Regulators in
Vietnam, Malaysia, Thailand, the Philippines, Indonesia and other
developing nuclear aspirants that ring the fault lines of much of the
Pacific Ocean need to candidly assess their nation's capacity to respond
in similar circumstances. Would they have the resources to deal with a
Fukushima-style incident, even apart from any question about the quality
of pre-disaster planning?
At some point in the
future even the most modern nuclear power systems on today's drawing
boards will appear antiquated compared to the day's technology. Fukushima
should give regulators both today and tomorrow pause in how they approach
the issue of safety in the face of technological evolution.
Mr. Stephens is a
Hong Kong-based senior partner with the firm Orrick, Herrington &
Sutcliffe.
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