On Wednesday, Gregory Jaczko, the chairman of the U.S. Nuclear Regulatory Commission, testified before a Senate subcommittee about the nuclear crisis in Japan. He assured the committee of "our continuing confidence in the safety of the U.S. commercial nuclear reactor fleet." In their opening statements, Jaczko and William Levis, an executive representing the industry's Nuclear Energy Institute, used variants of the words assure, ensure, and confident 21 times.
I don't want to hear the industry and its regulators talk this way after Fukushima. I don't want to hear confidence and assurances. I want to hear humility and a ruthless re-examination of assumptions.
I understand the need to put Fukushima in perspective. I agree with Jaczko and Levis about the relative safety of nuclear power. Measured by accidents, direct fatalities, and indirect health damage, nuclear energy is many times safer than fossil fuel production. It's even safer than hydroelectricity, which has killed thousands of people in dam failures. But the key to nuclear safety isn't confidence. It's doubt.
The power of modern science comes from its relentless self-scrutiny. Nothing is certain; everything is open to challenge. Karl Popper, the great philosopher of science, distilled the essence of the enterprise: We test hypotheses against reality not to prove them, which is impossible, but to falsify or modify them.
That's how we should think about Fukushima. The Fukushima Daiichi nuclear plant was built and upgraded according to the worst-case assumptions of the industry and its regulators. Those assumptions have just been spectacularly falsified. Our job now is to figure out what they got wrong.
In his written testimony, Jaczko told the committee:
There are many factors that assure us of ongoing domestic reactor safety. We have … used a philosophy of Defense-in-Depth, which recognizes that nuclear reactors require the highest standards of design, construction, oversight, and operation. … Designs for every individual reactor in this country take into account site-specific factors and include a detailed evaluation for natural events, such as earthquakes, tornadoes, hurricanes, floods, and tsunamis, as they relate to that site. There are multiple physical barriers to radiation in every reactor design. Additionally, there are both diverse and redundant safety systems that are required to be maintained in operable condition and frequently tested to ensure that the plant is in a high condition of readiness to respond to any situation.
It's true that reactors are designed to standards far higher than any oil, gas, or coal facility. And defense in depth—the inclusion of backup safeguards in case your primary safeguards fail—is exactly the kind of self-doubting philosophy Popper would have endorsed. But at Fukushima, our defenses weren't deep enough. The Daiichi facility's "evaluation for natural events" underestimated the magnitude and ramifications of the worst-case quake. The plant was "frequently tested" to ensure readiness for "any situation"—but apparently not for the situation that actually happened. The safety systems seemed "diverse and redundant" but in fact were all taken out by the same chain of events. And once the radiation began to leak, the country had no remotely operated vehicles prepared to fight the meltdown where humans couldn't go. It wasn't defense in depth that failed. It was our implementation of that idea.
The hearing was full of buzzwords conveying empty certainty. "Detailed evaluation" based on what details? "Frequently tested" against what? "Redundant" how? Levis, the industry executive, said, "U.S. nuclear power plants are safe" because they're designed "to manage the maximum credible challenges appropriate to each nuclear power plant site." Maximum credible challenges? I bet that's what Japanese executives used to say about Daiichi.
Jaczko told the committee that nuclear power stations being planned today "have enhanced designs and enhanced safety features that at least at the design stage and on paper seem to indicate that they would have an inherent safety advantage over the existing plants." But the Fukushima disaster wasn't on paper. It melted the paper on which previous safety assurances were based.