Support pylons of the Golden Gate Bridge, have several of them collide at the entrance to the Long Beach shipping terminal, blocking access for a few weeks, run over the deep water loading ports for crude oil. Run over a deep water drilling rig. I can think of any number of terrorist activities one could do. And remember, time and time again, no one really thinks of security until that "oh s___, we've been hacked" moment.

Not exactly, you will be arresting those who buy the stolen property. But hey, after a while people will start to get the idea.

Its amazing that technology and companies are finally catching up with the old Speed Racer cartoons.

Oh gee, our enemies are going to love this, the ability to nuke all the cells phones in the US at one shot. How much do you think a cracker could sell this exploit for?

Better solution: create a database of stolen IMEI numbers. In that way it can be reversed if/when the eventual screwup occurs.

Is anyone else suspicious of this announcement? Every article I can find is very vague on exactly how this is supposed to work. The one article I found that has a hint was it mentioning a filter with pores smaller than a water molecule. This infers they are extracting oxygen dissolved in the water. I wonder how much water one would need to pass through. Fish are cold blooded, and therefore have a lower metabolism than mammals. So we would need to filter a lot more water than a typical fish to make this work.

I wonder if Snowden is going to prove this guy a liar like everyone else.

The problem is, what do we replace it with? Right now, coal, oil, and natural gas are the only viable alternatives. All the places to put dams are already used, and we know how much they damage the local ecosystems. Windmills kill thousands of birds and bats every year. Solar would require destroying millions of acres of wilderness. Fusion has been 5 years away for the past 50 years. For the next 10 years I see nuclear and natural gas. At least we can cut down on the carbon dioxide, soot, and heavy metals going into the air. I'm hoping that energy storage from something like cyrogenic air storage will help, but I see it as at least 10 years away.

Not quite: the fissioning reaction is gone the moment you loose the water. The water acts as a modulator that slows down the neutrons to the right speed to have the best change of fissioning a uranium atom. This is not a bomb where you have 90% U235. In a reactor its usually 2-5%.

What causes the meltdown is actually the waste products of the reaction. The waste products are radiologically and thermally hot. If not cooled they cause the fuel rods to melt. The molten mass will go downwards absorbing more material until the heat output is less than can be absorbed by the surrounding environment.

The hydrogen explosion could not happen in the reactor chamber. What happens is that the reactor overheats, the zircornium reacts with the water. The oxygen atom is ripped away from the water to form zircronium oxide. The left over hydrogen cannot explode inside the reactor vessel because the oxygen is gone. So it leaks out and is eventually ignited.

Question for everyone: does anyone know if Fukushima has the US style concrete containment buildings? The explosions I saw on tv were clearly of an industrial type building, not the 6 foot reinforced concrete I'd expect of a containment building.

As for failures, one definite failure mode that was overlooked was for the grid power and the backup generators to be wiped out by the same event. That's called a common mode failure, and is one of the definite problems of nuclear power plants. Heck, of any system.

I don't know why the molten salt reactor was not pursued, but it was not because of the lack of the ability to produce nuclear weapons. As well as producing Pu239, power reactors produce lots of Pu238, Pu240, and Pu241. These guys are harmless in a nuclear reactor, but are a big problem in weapons. They tend to set the weapon off prematurely, which is usually a bad idea. These isotopes almost killed the original plutonium bomb until they learned to lessen the neutron exposure. If you want to produce weapons grade plutonium, you use a research reactor where the U238 can be exposed to neutrons for only a short period of time.

Nuclear weapons have close to 90% Uranium 235. Nuclear reactors are typically between 2 and 5% U-235. So divide the fuel mass by at least 20. If I remember correctly, typical burns are about 20% of the U235 before the waste products kill the reaction by neutron absorption.

Now what I do not know is which has more heat load: a brand new fuel rod running full bore for a few days, or an old fuel rod full of radio isotopes, but only running at half capacity due to the waste products. I'd guess the new one will at first, but it will cool off faster as it has fewer waste products.

MSR: Molten salt reactor? The one with the fuel chemically mixed with the salt? While interesting, I was never really a fan of that one. If you mean molten sodium, interesting, but kind of reactive. One I liked was a molten lead reactor. Easy to use coolent (if you can imagine using lead as a coolent). Self shielding (Its lead). High boiling point (compared to water), so low pressure primary system.

Use of thorium as a fuel instead of uranium. Because it emits 1.3 neutrons as opposed to uranium's 2, its almost impossible to use it in a nuclear weapon. And its much more plentiful then uranium. I don't recall if it has to be enriched or not.

If you are going with upgraded pressurized water reactors, you can change the cladding from zirconium (which reacts with water at high temperature) to a ceramic. The ceramic can have a melting point higher than the uranium can attain, so it can never melt. In addition I would go with passive cooling of the primary loop using systems that depend on gravity instead of pumps. Fewer moving parts and no chance that gravity is going to fail.

HTGR: high temperature gas cooled: Use of helium as a coolent. No water reactivity problems, more efficient. Some designs even include direct drive to the turbines instead of going through an intermediary loop.

For some interesting designs, check out traveling wave reactors. They are much more efficient at uranium usage. They can go something like 20 years without refueling.

And if you want to see a really radical concept, google "thorium laser".

From what I remember, there were at least 2 tests at that facility, they were successful. By MSR, do you mean molten salt? Personally I've always been a fan of the HTGR design. What I don't understand is why the NRC has not approved any design beyond the BWR and PWR designs. These designs are more than 40 years old. Think of using a computer or a car from 40 years ago. Instead of zircronium we can encase the fuel in ceramics whose melting point exceeds the maximum thermal output of the fuel. We have passive heat exchangers which depend on gravity instead of pumps. We have thorium designs that make nuclear proliferation almost impossible (or at least a heck of a lot harder). We have traveling wave designs that mean no refueling for 30 years. But instead we are stuck with designs from the 1960's.

They so called China syndrome (gee, I wonder what they call it in Japan?) was a guess as to what would happen in a worse case accident. I think it dates from the 60's or 70s, way before computer modeling was common. From the TMI accident, the presidential commission projected that if the containment building was breached, the radioactive material would penetrate 30-60 feet into the soil before coming to a rest. It would mix with the non heat generating material until the heat could be dispersed by radiation, at which time it would harden. Note: this is from memory. My copy of that report is in one of the boxes in my basement, which resembles the warehouse in Raiders of the Lost Ark.

Chernobyl also had a few design issues. One of the big ones is that the reactors were close to prompt neutron critical and had a positive reactivity thermal coefficient.

English translation: prompt neutron critical. Reactors need neutrons to keep going. There are two kinds, prompt and thermal (slow). Reactors are controlled by taking neutrons out of the mix using mechanical means (control rods, slow) or chemical means (boron in the water,slower). Both assume that the reaction is dependent on thermal neutrons.to continue. Once it is prompt neutron critical, there is no way in the world to stop it from exploding.

English translation: positive reactivity thermal coefficient. Neutron absorption and fissioning is dependent on temperature for different materials. Reactors (at least in the US) are designed so that once you go over a certain temperature, the neutrons are not as effective and the reaction slows down. This is negative thermal coefficient. Chernobyl was designed with a positive thermal coefficient, and they relied on the control mechanisms to keep it under control. The control mechanisms that they disabled for the test. The reaction started, the reactor heated up, made the reaction go faster, made the reactor heat up, it went prompt neutron critical, boom.