When I see a story like this, it reminds me that the events in Japan represent the biggest PR challenge the nuclear industry has faced in many years. Fifty billion dollars of nuclear reactor US taxpayer-backed loan guarantees hang in the balance.
The industry has been working for the past few decades to rehabilitate the image of nuclear power after Chernobyl and Three Mile Island, and now they have to contend with videos of a 1/2 mile tall mushroom cloud over a Japanese reactor and the continuing press coverage. Talk about challenging.
I think the HN community may have difficulty appreciating the challenges of nuclear reactor design because it is so different from software. In software, you have known bugs and unknown bugs. Once you've got the known bugs down to a low enough level and aren't finding too many new ones, you might release. The consequences of a bug is generally not too bad, certainly not on the order of making 800 square miles of real estate worthless, for example.
In engineering a nuclear plant, you have 90 tons of nuclear fuel generating 3,000,000,000 J of heat every second. The only reason it doesn't immediately turn into a big bubbling blob of molten uranium is that pumps the size of SUVs are pumping water over the fuel and removing all that heat. Every nuclear plant in the world is one minute from 90 tons of fuel melting into the basement if the water flow stops and fall-back systems fail. Fortunately, the engineering on these plants is done extremely carefully, with multiple independent systems in place to prevent exactly this by halting the nuclear chain reactions with neutron absorbing rods as well as by ensuring the flow of cooling water.
However, the events in Japan exposed an "unknown bug" in the design, that if you flood the basements of the plants with water you can lose backup power and coolant flow. While this particular "bug" is relatively easy to correct, it is a reminder that other unknown bugs may exist waiting to be exposed by other unexpected sets of circumstances.
It is good to remember Richard Feynman's quote about the space shuttle Challenger disaster, "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled."