Lawyers tend to be a negative bunch. Business lawyers tell entrepreneurs why they cannot do what they want to do. Lawyers for big corporations send threats to small businesses to keep them out of competition. Insurance defense lawyers spend hours deposing and cross-examining personal injury plaintiffs so they can claim everyone, including those barely able to walk, are malingering. Plaintiffs trial lawyers give long speeches, with the benefit of hindsight, for why health care professional or car manufacturer should have done everything differently.

There’s a reason for that negativity: lawyers generally do one of two things, try to prevent bad things from happening (which is what transactional lawyers and general counsel do) or prove who is responsible after something bad happens (which is what litigators and trial lawyers do).

Around here, we spend a lot of time investigating how things go wrong. One thing I’ve learned, particularly from the product liability and workplace accident cases, is that most major accidents these days — from scaffolding falls to gas explosions — were not only foreseeable, but were actually foreseen.

The ongoing nuclear meltdown in Japan — and it is a "meltdown" by this point in terms of the release of radioactive material, though there are substantially different degrees of meltdown, and, to get really technical, isn’t not even a meltdown but a "catastrophic disintegration of the cladding structural integrity and containment of fission products"  — is a case in point. Thousands of people read, linked to, and tweeted the elaborate and detailed explanation by Josef Oehmen, whose father was a nuclear engineer, as to why the situation in Japan would not be so bad. That article was later moved to the nuclear science department at MIT’s website, where they cleaned it up a little bit, but left it largely intact. The revised letter argues:

The entire primary loop of the nuclear reactor – the pressure vessel, pipes, and pumps that contain the coolant (water) – are housed in the containment structure.  This structure is the fourth barrier to radioactive material release. The containment structure is a hermetically (air tight) sealed, very thick structure made of steel and concrete. This structure is designed, built and tested for one single purpose: To contain, indefinitely, a complete core meltdown. To aid in this purpose, a large, thick concrete structure is poured around the containment structure and is referred to as the secondary containment.

The problem, however, is that Oehmen, and the MIT nuclear scientists, assumed that the nuclear reactors at Fukushima Daiichi were built to the best practices of the time in nuclear engineering. Indeed, as Oehmen / MIT suggests, in a properly designed and built nuclear reactor, if the control rods were inserted before the station lost power, then the worst-case scenario would be a contained meltdown. Nuclear reactors built to the state-of-the-art — even the state-of-the-art 40 years ago — are built with these types of "scram" failsafe measures that ensure containment of radioactivity in the event of the meltdown, even if the power and the cooling fails.

The problem, however, is that the reactor in Japan was not built to the state-of-the-art, not even the state-of-the-art back when it was built:

In some reactors, known as pressurized water reactors, the system is sealed inside a thick steel-and-cement tomb. Most nuclear reactors around the world are of this type.

But the type of containment vessel and pressure suppression system used in the failing reactors at Japan’s Fukushima Daiichi plant is physically less robust, and it has long been thought to be more susceptible to failure in an emergency than competing designs. In the United States, 23 reactors at 16 locations use the Mark 1 design, including the Oyster Creek plant in central New Jersey, the Dresden plant near Chicago and the Monticello plant near Minneapolis.

G.E. began making the Mark 1 boiling-water reactors in the 1960s, marketing them as cheaper and easier to build — in part because they used a comparatively smaller and less expensive containment structure.

American regulators began identifying weaknesses very early on.

The problem with the Mark 1 design — i.e., that its containment walls were not thick enough or strong enough — was not only foreseeable, but was actually foreseen at the time, but was not addressed because of cost concerns.

Indeed, the possibility of a major earthquake damage in the reactors was also not just foreseeable, but was actually foreseen, as shown by leaked diplomatic cables (courtesy of Wikileaks).

How could this happen? Simple: people were just too optimistic. Surely, they thought, the core would not be damaged, the power supply would be cut off, the backups power supply would fail, and the backup cooling systems would fail all the ones. Indeed, for more than a generation, they were right.

It’s not a problem peculiar to nuclear engineers. One of the longest studies of human longevity found that worrying was correlated with a longer life:

There are three reasons conscientious people tend to stay healthier and live longer. The first, and perhaps most obvious, is that conscientious people do more things to protect their health. They engage in fewer risky activities like smoking, drinking to excess, abusing drugs, or driving too fast.

The second, and not obvious, reason for the health benefits of conscientiousness is that some people actually seem to be biologically predisposed both to have that personality trait and to be healthier. They are less prone to a whole host of diseases, not just those caused by dangerous habits. It appears likely that conscientious and unconscientious people have different levels of certain chemicals in their brains, including serotonin, which may be involved.

The third and most intriguing reason they live longer is that having a conscientious personality leads people into healthier situations and relationships. They find their way to happier marriages, better friendships, and healthier work environments. And these things, we found, were key for longer life.

They found, intriguingly, that starting children on structured education too soon causes all sorts of problems, leading to shorter lifespans. Too much optimism in the parents, so to speak.

As much as we would all like to hope for the best, truth is, we are usually served better by expecting the worst. That is not to say we cannot ever take risks, but that we have to be mindful of the consequences, particularly mindful of what we will do if Plans A, B and C all fail.