Catch up on stories from the past week (and beyond) at the Slashdot story archive


Forgot your password?

Comment: Re:Seems obvious now (Score 4, Interesting) 210

by Rei (#49742243) Attached to: Secret Files Reveal UK Police Feared That Trekkies Could Turn On Society

Can you imagine the dystopian dictatorship where trekkies come to power? All of the halls of power full of people walking around in spandex and fake ears and brow ridges, the fed directed to work toward the absolution of currency, the military directed to accelerate development of phasers and for all recruits to undergo "Kobayashi Maru" training.... NASA would finally get their proposed $18,5 billion dollar annual budget passed - except that the bill would have the word "annual" crossed out and the word "monthly" written in its place. National anti-bullying legislation would be passed, probably with a name like Spock's Law. And of course they'd insist on referring to the UN as the United Federation of Planets.

Comment: Re:Satellites (Score 1) 401

by Rei (#49681273) Attached to: Ask Slashdot: After We're Gone, the Last Electrical Device Still Working?

LEDs have lifespans of what, 50-100k hours? So maybe a couple decades. And some will significantly outlive their design life, as is always the case with failure curves. The solar cells should be good for decades, until the contacts corrode.

One *could* design devices to last for thousands of years. But that's not usually a design constraint ;)

Comment: Re:Indian Point == Ticking Timb Bomb (Score 1) 213

by Rei (#49657421) Attached to: Transformer Explosion Closes Nuclear Plant Unit North of NYC

There's no guarantee that ECCS are independent and can operate in the vent of station blackout. The HPCI used in Fukishima, for example, is a steam turbine-driven pump but not a generator, and it has electrical components that require operation. Which is why it didn't prevent meltdown.

The primary turbines are not designed to operate on the amount of power generated from decay heat alone.

Comment: Re:Which Transformer exploded? (Score 2) 213

by Rei (#49657045) Attached to: Transformer Explosion Closes Nuclear Plant Unit North of NYC

Small upgrades, this already happens.

Large upgrades, by phasing out old units and building new ones. The complex as a whole remains.

Taking down an old unit is BTW a very large task ("decommissioning"), can take decades and comes at extreme expense. Which is part of why plant operators try to keep their old units going as long as possible, even when they've become expensive to operate.

Comment: Re:Indian Point == Ticking Timb Bomb (Score 4, Informative) 213

by Rei (#49657025) Attached to: Transformer Explosion Closes Nuclear Plant Unit North of NYC

Right, because generators the size needed to operate nuclear power plants are the sort of thing that you just pick up at any corner hardware store and "drive up and plug in"?

here's what one of those generators looks like. A nuclear power power plant may have a dozen or more in their generator building. Even replacing just one is not some sort of couple day task. These things take prep work and a lot of labour to acquire, move, install and set up. Weeks to months. That's all assuming that the generator building itself is still usable; a failure in such a large generator, or the sort of external event that can take out such a large generator, is not exactly some sort of low energy event.

Back before Fukushima people like you were all over Slashdot harping about how major nuclear disasters couldn't happen again, that it's only possible with old Soviet designs like Chernobyl that are horribly misused. Quit being so damned short sighted. Unforseen events and cascading failures do happen. You can't just act like "the list of causes of major that have already happened is the entire comprehensive list of what could cause major failures".

If you scram, lose your grid connection and lose your generators, you will likely get a Fukushima-like event. Two of the three happened here. Let's not pretend that the concept of something taking out the generator room, or otherwise preventing its power from working the pumps - generators which are only rarely tested - is such a preposterous concept. And let's not be silly and act like massive pieces of industrial equipment can just be plopped down and hooked up like a little Honda generator.

Comment: Re:Indian Point == Ticking Timb Bomb (Score 2, Informative) 213

by Rei (#49656883) Attached to: Transformer Explosion Closes Nuclear Plant Unit North of NYC

Actually, it is more dangerous than any other scram, as it means that you don't have a grid connection to power your cooling pumps. You have to rely on your backup generators. If they fail, you're in serious trouble.

As to the GP, nuclear's biggest problem is a "negative learning curve". We make a generation of nuclear reactors, but over time instead of getting cheaper to make and operate - as in most technologies - it gets more expensive as we discover all sorts of new things wrong and try to patch them. Some can be fixed, some are fundamental design problems. We try to work around this with a new generation of reactors - but that then starts the learning curve over from scratch, and often with an even more complex system.

It's been a real problem.

Comment: Re:Indian Point == Ticking Timb Bomb (Score 1) 213

by Rei (#49656873) Attached to: Transformer Explosion Closes Nuclear Plant Unit North of NYC

A transformer blowing up at a plant is actually a pretty big issue. An "off" PWR or BWR still needs power for quite a while for cooling. See Fukushima for the consequences of losing both mains power and backup generators at the same time. Clearly the backup generators worked - yeay! But what if they hadn't?

Indian Point, even in the event of a major accident, is not too much of a health threat to the people of New York City. Nuclear disasters are disasters in slow motion; you can run away from them, you don't have to sit around on contaminated streets drinking contaminated water. But what you can't do is ignore them. The financial costs if Indian Point underwent a Fukushima-scale disaster and large chunks of NYC had to be evacuated for long periods of time are almost unthinkable. That's the real problem with its positioning.

Comment: Re:Could be interesting, but will Uber last? (Score 3, Insightful) 45

by Rei (#49653925) Attached to: Uber Wants To Buy Nokia's Mapping Services

I think that's why Uber is trying to diversify, and fast. Amazing that so much money was thrown at this company whose business model was, as you put it, "basically illegal".

I'm going to start a netsharing company. We're going to put up wifi routers around town and charge people for net service, but we're not going to pay for the outbound connections. Instead we're going to wardrive around cities and wherever we find an poorly secured wifi network, we'll place a repeater there that routes our outbound net traffic through it. We'll be able to offer offer cheaper net access than everyone else, get a bunch of users, and thus a bunch of revenue, and we'll have a huge margin on our balance sheet. Who wants to toss us a few billion dollars?

Or maybe I should start a construction sharing company. We'll let anyone who wants to be a "builder" sign up and offer construction to anyone who wants the job done. No, they won't be licensed or have any sort of "permits", but that's not our issue, that's theirs. The point is, they'll be able to build things really cheap! And so we'll get a bunch of users, and thus a bunch of revenue, and we'll have a huge margin on our balance sheet. Who wants to toss us a few billion dollars?

Or maybe I should start a medicine sharing company... or a sex-for-money sharing company... or a software-license sharing company... or a gunsharing company... you see, if you add the word "sharing" to it, it's not really illegal!

Comment: Re:Wait (Score 1) 395

by Rei (#49648569) Attached to: 25 Percent of Cars Cause 90 Percent of Air Pollution

Huh? Biking is the most energy efficient way to get around (more efficient than walking).

Which is why electric bicycles are a very efficient way to get around. But we're not talking about electric bikes; we're talking about human powered bikes. And unfortunately, the CO2 footprint per unit energy out of growing food, harvesting it, shipping it, cooking it, digesting it, and turning it back to kinetic energy via the muscles, is often ridiculously high compared to far more efficient ways of harvesting chemical energy (such as directly burning it in an ICE or gas turbine)

If a cyclist's energy comes overwhelmingly from efficient, locally grown starchy / fatty plant sources, the efficiency of a bicycle can overwhelm the inefficiency of using food as an energy source, and they can get a better CO2 footprint per kilometer than a Prius. On the other hand, that's not a typical diet. If half their calories are from beef, for example, they might as well be driving alone in an SUV.

One thing to keep in mind is the carbon cycle. Burning gas / oil / coal unlocks carbon that has been locked away for a loooooooooooooooooooong time

Are you under the impression that the CO2 footprints from food production don't?

And note that right now I'm only talking about CO2 footprints. Should we also go into the vast amounts of habitat destruction and water consumption used to produce food? Take a look at a satellite image of how much of our planet we've turned into a food-producing machine, and all of the rivers that no longer reach the ocean, or are so full of fertilizers that they make dead zones. Let's not pretend that the act of voluntarily consuming more calories (aka, exercise) is unrelated.

And exercise is good for you.

Note that my post wasn't about health. :) This is absolutely true, most people would benefit from more exercise, health-wise (although too much is also bad for you). Although cycling does put you at much greater risk of injury than driving.

Also, see this post.

It's perfectly reasonable to look at all aspects - health, injury, CO2, etc. But I find that all too many people are not only willing to ignore the negative effects of cycling or walking as a mode of transportation, but even get shocked and indignant when someone points them out (see the responses to my post for examples, including the speechless "What? No. Seriously." response).

There are good health effects for people who need more exercise. But there also are negative effects (injury, CO2, land and water use, etc), and let's not pretend that they don't exist.

Comment: Re:Wait (Score 3, Insightful) 395

by Rei (#49648419) Attached to: 25 Percent of Cars Cause 90 Percent of Air Pollution

They burn more calories (that's where the energy for propulsion comes from). Calories come from food. If meat is part of their diet, then yes, they eat more meat. Which has a huge CO2 footprint associated with it. Vegetables too have often very high CO2 footprints per calorie (because they have so few calories). As does anything shipped in from long distances away.

A cyclist can maintain a low CO2 footprint, but only by eating a diet that has low CO2 emissions per calorie - for example, locally grown grains, potatoes, etc.

Now, an electric bicycle is a different story; they have incredibly low CO2 footprints.

(It's not just a stereotype that athletes eat big meals after a big game or hard workout. They have to to not lose weight to the point that they lose energy and their body starts to eat itself. While a disturbing number of people seem to have this notion that exercise is "free energy", it's simply not the reality. Yes, a person being fit and thin by exercising regularly will have a somewhat lower baseline metabolism. But it's not even close to the number of calories they burn to get there.)

There is one way to find out if a man is honest -- ask him. If he says "Yes" you know he is crooked. -- Groucho Marx