The “impossible” is underway in Japan. A 9.0 magnitude earthquake has badly shaken up several “indestructible” nuclear plants. Reactor No. 1 at the quake-damaged Fukushima Daiichi Nuclear Power Station is in partial meltdown, and reactor No. 3 may soon join it. In an act of naked desperation, plant officials are blindly pumping seawater into reactor No. 1 in an effort to cool its fuel rods.

In all, four nuclear plants across northeast Japan are damaged, with a total of six reactors now having trouble cooling their radioactive uranium fuel rods. One major problem is that the quake destroyed all backup electrical power systems, so there is now very little juice to run equipment.

The worst off is the Fukushima Daiichi nuclear complex, where the No. 1 reactor containment building exploded on Saturday when radioactive hydrogen gas was vented from the containment vessel inside it. Mixing with oxygen, the hydrogen ignited. More venting is due at reactor No. 3, thus a second such explosion is feared imminently (and may have occurred by the time you read this).

As day three of this disaster drew to a close, I reached former Nuclear Regulatory Commissioner Peter Bradford by phone at his home in Peru, Vermont. Now an adjunct professor at Vermont Law School, Bradford was a Carter-appointee to the Nuclear Regulatory Commission (NRC) and was on duty for the partial meltdown at Three Mile Island in 1979.

“It’s very hard to know what’s going on,” said Bradford with a grim calm. “During Three Mile Island very much of what we believed to be true on day three turned out to be untrue in subsequent days. Even now, we still don’t know how much radiation was actually released. It was less than was later released at Chernobyl, less than could have been released had the containment vessel failed. But how much was released? We don’t actually know.”

As for the multifaceted atomic crisis in Japan, it is very hard to say what is really going on. But this much is clear: if the containment vessel at the partially melted-down Fukushima reactor No. 1 holds, most of the radiation should be held within the site.

That is the Three Mile Island scenario, which the International Atomic Energy Agency rates as a four on its Nuclear and Radiological Events Scale. The crisis in Japan is, so far, a five. Chernobyl was a seven.

If the containment vessel breaks—or is already broken, cracked and leaking due to the earthquake—and if the meltdown keeps going, officials would have to switch from trying to cool the reactor to burying it with tons of sand and cement, essentially bombing it with dirt in numerous and very dangerous air sorties by cargo planes and helicopters.

That would be the Chernobyl scenario, and it would mean that massive amounts of radioactive iodine, cesium and other very poisonous stuff would escape into the atmosphere. This contamination would be deadly close to the site, but could reach the West Coast and even the East Coast of the United States—though in a very diffuse form.

The fallout from Chernobyl left swaths of Belarus and Ukraine red-hot no-go areas of contamination, inhabited by mutant wild boar and other strange fauna. The radiation from one or two Japanese Chernobyls could sicken many thousands of people—and many of them could die. The fallout’s diffusions across the Northern Hemisphere would strike later and quietly, as hard-to-track cancers seemingly unlinked to any one cause.

And what about our reactors? In the United States we have twenty-three reactors of the same General Electric design as Fukushima No. 1. We also have atomic plants built on fault lines. For example, the Diablo Canyon Nuclear Power Plant’s units 1 and 2 not far from Santa Barbara, and outside San Clemente there’s the San Onofre Nuclear Generating Station, which has three reactors, two of which are still running. Environmentalists protested and bitterly opposed the opening of these plants along the California coast in a region of regular and often violent seismic activity. But as in Japan, their concerns were brushed aside with assurances that all contingencies had been taken into account.

The American fleet of 103 atomic reactors is old and rickety. But more dangerous than the old and brittle equipment, according to Bradford, may be overconfidence among regulators and managers. “The phrase ‘it can’t happen here’ is an invitation to disaster,” said Bradford. Mix technological arrogance with the profit motive, and you get slipshod management, corner-cutting and repeated lying.

As I’ve detailed in these pages in the past the American discourse around nuclear energy is somewhat schizophrenic. At one level, conservatives and some greens carry on a profoundly out-of-touch discussion about the merits of fourth-generation and miniature nuclear power plants. None of these schemes will be built due to their extremely prohibitive costs.

But in the meantime, there is an overlooked yet very real campaign by industry to relicense and extend by 50 percent the operation of our rickety old existing fleet of reactors. And get this—a quarter of our reactors are leaking or have leaked radioactive carcinogenic, tritium-polluted water. (See “Zombie Nuke Plants,” December 7, 2009.)

Vermont Yankee is one of the nukes up for relicensing, and it also has a tritium leak than no one can seem to find or stop. At first company officials from Entergy of Louisiana just lied about the problem, telling state regulators and lawmakers that the plant did not have the sort of underground pipes that could leak tritium into groundwater. But it does.

So far more than half of America’s commercial nuclear reactors have received new twenty-year operating licenses. In fact, the NRC has not rejected a single license renewal application. Many of these plants have also received “power-up rates” which allow them to run at up to 120 percent of their originally intended capacity. That means their systems are subjected to unprecedented amounts of heat, pressure, corrosion, stress and embrittling radiation.

The only thing that could make our nukes safer would be a campaign of constant, careful, rigorous (and expensive) inspection and maintenance. But the NRC does not require that. During his campaign, Obama called the NRC “a moribund agency…captive of the industry that it regulates.” Unfortunately, that has not changed much since Obama took office. And the private companies running the plants—armed with notions of infallibility and motivated by money—are doing all they can to squeeze yet more money from the aging nuke fleet.