Follow Slashdot blog updates by subscribing to our blog RSS feed


Forgot your password?
Check out the new SourceForge HTML5 internet speed test! No Flash necessary and runs on all devices. ×

Comment Re:Im not trying to be that guy.. (Score 1) 41

Assuming it isn't a solid rocket, it must contain an oxidizer tank in addition to the fuel tank or else it wouldn't be a very effective rocket. When the fuel combines with the oxidizer, it produces an exothermic reaction.

... unless, of course, somebody forgot to fill the oxidizer tank, in which case that's probably why there's a giant probe-shaped crater on the surface of Mars now.

Comment Re:6.8 Billion (Score 1) 290

Yes. I've run numbers before. No, I'm not going to be bothered to do them again for a Slashdot chat on a thread that's rapidly becoming out of date. Feel free to do your own if you doubt me. Take a sampling of solar plants with a realistic capacity factor and a sampling of hydro plants with a realistic capacity factor, and compare. You'll need a broader sampling on hydro because solar thermal plants are "fairly" consistent (with the exception of compact linear fresnel plants, of which last I checked there was only one), while hydro reservoir sizes vary wildly for a given output.

Comment Re:6.8 Billion (Score 1) 290

No, a RTG is distinctly different from a nuclear reactor in almost every single way. They do not involve chain reactions. They do not involve neutrons to any significant degree. Moderation, cross section calculations, etc don't even come into play. It's just a ball of material that stays hot due to capturing its own alphas. RTGs are not considered nuclear reactors. There is no wiggle room on this; they're an entirely different class of spacecraft power systems.

RTGs scale down quite well. They're also, however, about as far on the opposite side of the affordability spectrum as you could possibly get.

There have been actual nuclear reactors used on spacecraft in the past, as I wrote, primarily by the Soviets. But they're anything what you'd consider a cost effective design for civilian power generation.

Comment Re:6.8 Billion (Score 1) 290

Higher fissile number density = higher enrichment = nonstarter. Fine for submarines, not for civilian power. Re, reflector, you still have to deal with free path issues when determining overall reactor size. The more you're spending on inert mass relative to how much power you're getting, the worse your economics. Plus your reflector is contributing to (n, gamma) and other neutron consuming reactions (although it's possible to use a moderator that you need anyway (say graphite) as a reflector... although there are issues with that as well to deal with)

You'll note that I mentioned and agreed with the mass production argument - if fission power is going to have an actually sustainable renaissance, I would expect modular reactors to be the means. But I nonetheless questioned whether that could be enough to overcome the basic issues on top of the additional challenges that a small modular reactor imposes.

Comment Re:6.8 Billion (Score 1) 290

Energy density (with respect to time) - J/m^2-s or equivalent.

As for "Who cares?" The GP for one. Me for two. Most people on Earth as well. The more land that is used up, the less you have for other purposes, be that for humans (agriculture, forestry, mining, grazing, etc) or natural habitat. It hits doubly that reservoirs target land defined most notably by the following characteristics:

1) Large river
2) Deep ravine/basin
3) Significant altitude change

In short, they often tend to be the areas most important to wildlife, often locally-unique habitats, as well as the most scenic areas within a given location - areas responsible as well for significant mobilization of sediment and oxygenation of water.

Solar, by contrast benefits most from environments full of endless identical flat wastelands. The more mundane and barren, the better.

Comment No, you cannot have an "alternative opinion" (Score 1) 478

At least if you are a professional in a field.

Because I would expect my professional to be at the level of current science and technology. I do expect my mechanic to think that sand isn't the best lubricant for my gear box, I do expect my doctor to know that it's not a good idea to sprinkle holy water that he got from the holy pond in his garden into my open chest wound and I do expect my IT security guy to know that it's not a good idea to let the new server sit on the ley line in front of our HQ for a night to absorb the good energies.

If you want to believe that, great. But get out of your field of work before you do. If you want to offer "alternative" stuff, move into that profession instead. I am sure there is a market for that too, else people would not have invented that snake oil. But if you are my nurse and responsible for working on my child, I do fucking EXPECT you to give him or her that MMR shots and not avoid it because you "don't believe in it".

Comment Re:Incidents vs. population? (Score 1) 250

Because people are stupid and don't understand statistics.

An example: Imagine there is an ultra rare disease that one in 100 million people gets. Now imagine there is a test for it with a 0.001% error margin (i.e. 0.001% of test results are false).

Is that test worth anything?

Comment Re:There's certainly a place for that, a ROI point (Score 2) 46

You can have us for a little over 1000 a day. And you can find a LOT of security flaws in a day. I dare say hiring a pentester for 2 days can close 80% of your security holes, and since they're going for the same low hanging fruits that black hats go for, this should make you safe, unless you're a high profile target where someone really, really, really wants to hack you and is willing and able to spend the time for that.

Slashdot Top Deals

No problem is so large it can't be fit in somewhere.