For the clearest picture of what is happening at Japan's Fukushima Daiichi nuclear power plant, talk to scientists thousands of miles away.
Thanks to the unfamiliar but sophisticated art of atomic forensics, experts around the world have been able to document the situation vividly. Over decades, they have become very good at illuminating the hidden workings of nuclear power plants from afar, turning scraps of information into detailed analyses.
For example, an analysis by a French energy company revealed far more about the condition of the plant's reactors than the Japanese have ever described: water levels at the reactor cores dropping by as much as three-quarters, and temperatures in those cores soaring to nearly 5,000 degrees Fahrenheit, hot enough to burn and melt the zirconium casings that protect the fuel rods.
The evaluations also show that reactors at Fukushima escaped the deadliest outcomes — a complete meltdown of the plant. Most of these computer-based forensics systems were developed after the 1979 partial meltdown at Three Mile Island, when regulators found they were essentially blind to what was happening in the reactor. Since then, to satisfy regulators, companies that run nuclear power plants use snippets of information coming out of a plant to develop simulations of what is happening inside and to perform a variety of risk evaluations.
Indeed, the detailed assessments of the Japanese reactors that Energy Secretary Steven Chu gave on Friday, when he told reporters that about 70% of the core of one reactor had been damaged, and that another reactor had undergone a 33 % meltdown came from forensic modeling.
The bits of information that drive these analyses range from the simple to the complex. They can include everything from the length of time a reactor core lacked cooling water to the subtleties of the gases and radioactive particles being emitted. Engineers feed the data points into computer simulations that churn out detailed portraits of the imperceptible, including many specifics on the melting of the hot fuel cores.
Governments now possess dozens of these independently developed computer programs, known in industry jargon as 'safety codes'. "Many of these institutions -- including ones in Japan -- are relying on forensic modeling to analyze the disaster at Fukushima to plan for a range of activities, from evacuations to forecasting the likely outcome.