Is This A Good Idea : Science Channel

March 16, 2011

Like many of you, I've been anxiously watching events in Japan, where Friday's catastrophic magnitude-9.0 earthquake, in addition to killing and injuring thousands of people and causing many billions of dollars in property damage, has created a potentially even more dire crisis at the badly damaged Fukushima-Daiichi nuclear power plant 150 miles north of Tokyo. New Scientist's frequently updated blog on the nuclear situation reported Monday morning that engineers were struggling to stabilize two of the plant's six reactors. That afternoon, news outlets reported that a third reactor's cooling system had failed. The details are emerging in frenetic, confusing bursts, but the gist seems to be that the quake caused breakdowns of the reactors' cooling systems, exposing the fuel rods to air -- which causes them to overheat -- and creating the potential risk of core meltdowns and breaches of the reactors' containment structures. The worst-case scenario would be a major release of radiation into the atmosphere.

Union of Concerned Scientists blogger Ed Lyman writes that reactor 3 is a particular worry, because 6 percent of the core is mixture of plutonium and uranium oxides, called MOX, which contains ingredients with higher radio-toxicities than other fuel mixes.

Because of this, the number of latent cancer fatalities resulting from an accident could increase by as much as a factor of five for a full core of MOX fuel compared to the same accident with no MOX. Fortunately, as noted above, the fraction of the fuel in this reactor that is MOX is small. Even so, I would estimate this could cause a roughly 10% increase in latent cancer fatalities if there were a severe accident with core melt and containment breach, which has not happened at this point and hopefully will not.

Lyman cites a recent study by Sandia National Laboratory that suggests that in the event of a meltdown at the reactors, there's about a 42 percent risk of a containment breach. (The reactors, which were built in the 1960s, have Mark I containment vessels, which are believed to be particularly vulnerable.) Scientific American blogger Steve Mirsky explains that the Japanese reactors have relatively small containments compared with the damaged unit 2 reactor at the Three Mile Island plant in Pennsylvania (that suffered a partial meltdown in 1979), and lack the additional layers of protection that were in place to prevent a catastrophic breach there.

If there is a major radiation release from Fukushima-Daiichi, what would be the danger? It's hard to say. We still don't have a clear picture of the health impacts of the 1986 Chernobyl disaster in the then-Soviet Union, in part because cancers and other health problems caused by exposure may take many years to develop. (On the optimistic side, this 2008 U.N. report suggests that millions of people in the surrounding region may only have been subjected to small doses of radiation, so that the harm may not be as great as was once feared.)

I confess that it's not just concern about the Japanese that has me feeling uneasy. Back in early 2008, I wrote this blog post in which I reconsidered my long-standing qualms about nuclear power, given the burgeoning problem of climate change and our pressing need to transition away from the carbon-based energy generation that is pumping vast quantities of greenhouse gases into the atmosphere. I quoted a seminal 2006 Washington Post opinion piece by former Greenpeace International director Patrick Moore, who argued that nuclear power was a more viable source of greenhouse emissions-free power than other alternative energy sources:

Wind and solar power have their place, but because they are intermittent and unpredictable they simply can't replace big baseload plants such as coal, nuclear and hydroelectric. Natural gas, a fossil fuel, is too expensive already, and its price is too volatile to risk building big baseload plants. Given that hydroelectric resources are built pretty much to capacity, nuclear is, by elimination, the only viable substitute for coal. It's that simple.

But Moore made that assessment before Fukushima-Daiichi went haywire and people started eyeing the weather vanes to see if the wind was blowing toward Tokyo. Should we be worried that building more nuclear plants in the U.S. would raise the possibility of a Fukushima-like crisis here? Do we need to re-compute the risk-benefit analysis?

Before we get to that, there's some debate about whether the U.S.'s 104 aging nuclear plants are sufficiently hardened against the risk of seismic disturbances. The Nuclear Energy Institute, an industry group, notes in this article that the plants were designed to withstand the biggest earthquake that scientists could project for their locations, and then some. But how foolproof are those safeguards? Here also is a 2005 Nuclear Regulatory Commission document noting that the potential risk has been revised upward for some plants, based on new geological information. And nuclear power opponent Friends of the Earth points out in this article that many of the U.S. plants are the same vintage as Fukushima-Daiichi and employ similar technologies -- with similar vulnerabilities.

The more significant question, however, is whether the next-generation plants that proponents want to build would be significantly safer than the old ones. We'd certainly expect that to be the case, considering all the technological advances over the past several decades. (After all, today's cars are much safer than Corvairs and Pintos.)That's why I was dismayed to discover this June 2010 article, by former Philadelphia Inquirer reporter Susan Q. Stranahan, on Yale's Environment 360 website. She reports that reactors today are designed to be more resistant to internal breakdowns, such as pipe breaks or fires. However:

When risks of damage caused by external events -- earthquakes, for example -- are factored in, the new reactors are no safer than older reactors. In addition, because utilities have no operating experience with the new reactors, the probable risk assessments are purely theoretical and not as reliable as years of actual operating data from existing plants.

And here's the really worrisome part:

The new designs are engineered only to withstand a predictable sequence of events, something engineers theorize may happen. In nuclear parlance that is called a “design basis accident.” The new reactors, like their older counterparts, are not designed to survive an unexpected sequence of events.

Even as someone who is willing to accept some of the downsides of nuclear power -- the dilemma of finding a way to dispose of nuclear waste, for example -- I'm left wondering whether we should go ahead with approving construction of more plants. At the very least, I want to know why we can't have new designs capable of coping with unforeseen events. Because that's what reality too often throws at us.

What's your opinion? Express it below.

Image Credits: Lui Siu Wai/XinHua/Xinhua Press/Corbis | Yang Chun/XinHua/Xinhua Press/Corbis