By Bob McDonald, host of the CBC Radio One science program Quirks & Quarks.

Amid cries of "Another Chornobyl!", technicians at the Fukushima Daiichi nuclear plant in Japan have done an astonishing job, making sure an already bad situation doesn't turn into a global problem.

With heroic courage and risking their own health, the operators remained on site during an earthquake larger than the reactor was designed for, to ensure that it shut down immediately, which it did. Control rods were inserted into the nuclear cores, stopping the fission reactions.

For an hour, one of the oldest reactors in the country, only two weeks away from its 40-year decommissioning, did what it was supposed to do: running pumps to circulate cooling water to the reactor cores on emergency back-up power.

Then the lights went out as the tsunami swept through the complex, wiping out the diesel generators and allowing the reactors to begin a steady, uncontrolled rise in temperature, with the frightening possibility of a meltdown and catastrophic explosion.

But that didn't happen.

While the region's infrastructure of roads, electrical grid, gas lines and water mains lay in ruins from the tsunami, the technicians, with only a matter of hours of battery power available, scrambled to jury-rig hoses and secondary pumps to bring cool seawater into the reactors to keep them from running dry, like a kettle that has run out of water.

Nuclear reactors are really just elaborate boilers, with the uranium fuel rods acting as heating elements to produce steam to run turbine generators. When any boiler runs dry, the heating elements will overheat. But you can't just unplug a nuclear reactor like you can a kettle. The fuel rods continue to get hot on their own because of residual fission and other reactions taking place. That's why cooling water must continue to circulate, even after the reactor is shut down.

As water began to boil off, steam containing hydrogen gas began to build up inside the outer containment vessel. Even with the knowledge that hydrogen is explosive and the steam was slightly radioactive, the decision was made to release it, rather than let the reactor itself blow. That triggered the spectacular explosions that tore the roofs off the outer buildings and made television headlines around the world. But the reactors themselves were still intact; the nuclear fuel still contained.

It was at this point, with the sight of the brown cloud rising from the shattered remains of the building, that comparisons to Chornobyl were made.  But in fact, the two scenarios were very different.

The Russian disaster involved a gigantic steam explosion and fire that destroyed the entire reactor and blew the remains into the stratosphere. The Japanese explosions were only the hydrogen gas blowing out the outermost of three containment structures.

As the week wore on, another emergency developed, separate from the overheating reactors, as water leaked out of containment pools which hold spent fuel rods. Again, water supply was the issue, whether it came from helicopters, fire trucks or wherever. Just keep those rods covered.

The situation is far from over, but at this point, five people have been lost due to the hydrogen explosions and a crane accident. No one has died from escaping nuclear fuel. Evacuations around the site are precautionary, as they should be. Meanwhile, the other nuclear reactors in Japan are coming back online to restore power to the devastated region, including the Fukushima plant. It's an amazing success story amid an unbelievable natural disaster.

This is only the third major nuclear accident in more than 65 years of nuclear power. No lives were lost at Three Mile Island, and no nuclear fuel was released into the environment, even though that accident involved a core meltdown. The Chornobyl accident is the only one that involved loss of life, but it was caused by human error, not a flaw in the reactor.  

By comparison, thousands lose their lives every year from the fossil fuel industry: coal mining, coal combustion, oil rig explosions such as the one in the Gulf of Mexico, drilling accidents, gas pipeline explosions, refinery fires, tanker accidents; not to mention the environmental impact of emissions from all those smoke stacks and tail pipes.

Yet we condemn nuclear power while accepting the much more dangerous, dirty and limited fossil fuels.  

As you will hear on Quirks this week, a new generation of safer, more efficient nuclear generators is on the drawing boards, to meet our ever-increasing demand for energy.

Considering how well a reactor design from the 1960s survived the worst disaster Japan has seen in 50 years, the prospects for the future of nuclear power seem like a pretty safe bet.