As a rational human, I’m aware of finding my emotions and prejudices conflicting quite often with my knowledge of science and reality. Being reasonable is relatively new to us apes, and a hundred million years of evolving reactionary emotions usually takes precedent.
So I find myself pretty conflicted about his video, which shows five men in July, 1957, standing around in the Nevada desert while a nuclear weapon is detonated above their heads.
[Note: the video says the detonation was 10,000 feet above their heads, but that is erroneous; it was more than 18,000 feet.]
This video comes from NPR via my own Discover Magazine. [Given what follows below, I'll note that the NPR article shows that these men were not adversely affected by the blast, and most lived to be old men. I strongly urge you to read that entire article, in fact. It's fascinating.]
When I watched the video, my feelings were curious. My first reaction was visceral: basically just "Aiieeeeee!"
But that was immediately followed by, "Well, the blast was low yield and about 18,000 feet up, so the odds of them getting hurt by it were pretty small."
The thing is, both thoughts are right! Here’s why.
The blast was indeed a small one. It was not a fusion bomb (usually called a thermonuclear or H-bomb), but instead was a fission bomb, an A-bomb. These release far less energy when they explode, though it’s nothing to be trifled with. This particular test was done using a 2 kiloton yield; in other words, it exploded with the energy of 2000 tons of TNT. For comparison, the only two atomic weapons used in wartime – by the US over Hiroshima and Nagasaki – had yields of about 13,000 and 21,000 tons of TNT. Hydrogen bombs have yields typically measured using megatons, or millions of tons of TNT.
So the explosion in this video was bigger than a usual conventional bomb, but not nearly as big as what we normally think of as a nuclear bomb. Right away we have to be careful how we think of this!
Second, the explosion was at a height of well over 5 kilometers (3 miles). As I pointed out in a recent BAFact, Earth’s air is quite good at absorbing various types of electromagnetic radiation (a fancy name for "light"), including X-rays and gamma rays. The men under the blast probably received no direct dose of ionizing radiation in that form. It’s possible the intense high-energy light from the bomb created secondary forms of radiation – high-speed electrons and so on – but again, the bomb yield was low, so all that air probably did a pretty good job stopping all that.
Third, what about fallout? This is radioactive material from the blast that falls from the sky. In an atomic (or an H) bomb, radioactive atoms are created and dispersed. In low altitude tests, the heat from the explosion can draw up dust from the ground, mix it with these materials, and create a radioactive cloud that can travel a long way. Raindrops can form, and the radioactive brew can literally fall out from the sky.
[UPDATE: Wow, minutes after I posted this, an explosion is being reported at the third reactor site. I mentioned in this post the third reactor was in trouble, so this may be another hydrogen combustion explosion as happened in the other two. I'll put more updates here as I find them.]
[UPDATE 2: The comments being posted below are contradictory, as I expected; news is coming quickly about the third explosion and speculation is flowing. I'll add that I freely admit things I wrote below may be in error; but they are based on what I've read and heard over the past few days. With news being as spotty as it is, that's inevitable. That's why I made the disclaimer I did in the post.]
[UPDATE 3: Alan Boyle at Cosmic Log has an excellent and calm discussion of what happened, including best and worst case scenarios.]
[UPDATE 4 (20:30 Mountain time): Yikes. The New York Times -- not generally known for breathless overreaction -- is reporting that the explosion from reactor 2 may have damaged the containment vessel of the nuclear core. The exact situation is still maddeningly unclear. Both best and worst case scenarios are being spun, but as usual I will wait for more information before drawing any conclusions. In the meantime, there may be evacuations of personnel from the plant. I hope that's not true; those people are the ones heroically working to keep this matter under control.]
[UPDATE 5 (March 15, 22:00 Mountain Time): I haven't updated today because until now not much news was coming out about the reactors, and some of the news I did see was clearly contradicted by other reports. However, The Associated Press is reporting that all the workers at the plant have been evacuated. This is bad news. Those people have been working heroically to keep things under control, despite some temporary but scary surges in radiation levels around the plant. The AP article itself has contradictory statements by experts -- one saying it's a matter of time now, and another saying there is minimal risk to the population. It was reporting like this that led me to write this article in the first place, and clearly some of the things on which I was basing my conclusions have changed. If there are any major developments, good or bad, I'll update here and most likely write a new post given what we've learned in the past few days.]
After the earthquake and tsunami in Japan, things over there are very, very bad. The pictures and video of the devastation are incredible… and before I go any further I will note that science and engineering mitigated this disaster by orders of magnitude. The Japanese have prepared for this type of event for decades, and it’s paid off. At this time, the number of dead is in the thousands… not the hundreds of thousands. I will not downplay the tragedy and loss, but it could’ve been far worse.
Still, there are many problems. One of the biggest* is the Fukushima Daiichi nuclear plant, which is facing a crisis with its reactors. While this situation is serious, let me be very clear: we are not facing a nuclear explosion, nor are we facing the release of a huge, deadly radioactive cloud (more on both of these below). The fear-mongering and misinformation on the web and in the news is rampant, and the last thing we need is people panicking because of it! The news is bad enough without exaggeration of it.
The best analysis I’ve seen so far is at Slate. An excellent summary is also on The Market Ticker. At reddit, a commenter gave a very short description, and Boing Boing also has a good piece. [Update: My friend Evelyn Mervine, who is a PhD candidate in geology, has a series of interview with her nuclear engineer father on her website.]
This situation is changing all the time, so please be aware that what I write here is based on what I’ve read in those articles, what I’ve seen in the news, and my own knowledge. With things being so fluid, caveat lector.
Here’s what happened: The plant has six reactors. The earthquake and subsequent tsunami severely damaged some of the reactors and hampered attempts to fix them. An explosion rocked the plant on Saturday, and another about a day later. These were not nuclear explosions! That is literally impossible from a fission reactor; the fuel is the wrong kind and doesn’t have sufficient quantities to explode like an atomic bomb. Instead, the explosions were due to hydrogen combustion, created when water came into contact with the extremely hot fuel cells. The cooling system was down, allowing the fuel cells to heat up. Hydrogen was released, and is extremely volatile. It volatilized.
The explosions destroyed the reactor buildings (basically an enclosure around the reactor itself to protect it from the elements), but far more importantly it appears the reactor housings are intact. Engineers are now using seawater to cool the reactors, which will ruin them for future use but should safely cool the fuel rods. This situation isn’t over yet (a third reactor is in trouble as well), but I’m cautiously optimistic this plant will be shut down safely. Ironically, it was two weeks from its scheduled 40 year decommissioning as it was.
That isn’t stopping the rampant speculation fueled by fear and ignorance of the real situation. For example, I’ve seen some people calling that blast a nuclear explosion, but it wasn’t. Again, it was hydrogen exploding when it reacted with air. A huge explosion, but not a nuclear one.