A million dB gain is a gain of 10^100000, not 10^9. If you want to hear things at Alpha Centauri with the same signal strength as you hear things in geosynchronous orbit, your 10^26/10^6 ratio is right: you need to add 200 dB gain. I don't think you really have a whip antenna plus amplifier that gets 200 dB gain, but if you did, you'd be getting close to what you need. (Of course, you need to block the noise from Alpha Centauri, too.)
However, this kind of service usually comes at a cost.
That's not always true, but when it is: don't put anything valuable there. If you have something valuable that you want to put online, and can't find a free host that lets you keep backups, then spend some money.
For most bloggers, it's the content of their posts that matters. They don't need byte-to-byte backup.
By valuable, I mean something that you'd like to come back to and re-use sometime in the future. Throwaways like/. posts don't need backups. Things you spend time on do.
And a corollary to the parent's good advice: if you can't easily get a complete copy of your work, find another host. Manual one-by-one downloads don't cut it.
Just checked, here's the link. One part I find particularly telling:
Make sure you deauthorize your computer before you upgrade your RAM, hard disk or other system components, or reinstall Windows. If you do not deauthorize your computer before you upgrade these components, one computer may use multiple authorizations.
One doesn't always get to choose when to change system components, sometimes they choose to fail on their own.
Apple's DRM doesn't allow you to deauthorize a machine that you don't have access to, unless you deauthorize all your machines, and you can only do that once a year.
A friend of mine complained about having the choice of pirating or re-purchasing a large collection of classical music, when his licensed system died, and he was out of allowed installs. I don't know how hard he tried to work around the problem, but in his view, it didn't always "just work".
Does MS offer a way for Google, Apple, etc. to register that they've got an update available, so they could use the standard update mechanism, instead of writing their own?
Not that Apple would choose to use it: they like to mix ads in with their updates, but I can see some other projects taking advantage of this.
Then again, I only use Firefox, and would never consider using IE.
It's harder to avoid than you seem to think. If you use Windows help to view.chm files, you're using IE. Usually they stay local, but many help files do include links to web pages, and then you're out in the real world.
Thanks for the long post, in which you managed to include one fact, along with the insults. Too bad the fact was wrong. Uranium fuel is rarely metallic uranium (it would melt), it's usually an oxide (with a number of variations used in different reactors).
And your claim many posts ago that spent fuel emits only alpha particles was just bizarre.
So I have to wonder about your qualifications. I'd guess you're an undergrad engineering student from the way you write, but your nickname makes it look as though you're not out of high school yet.
One more followup. I found the book "Nuclear Energy in the 21st Century: World Nuclear University Press" by Ian Hore-Lacy, which actually gives some plots. I'd have preferred something more technical, but I'll take what I can get.
According to Fig 19 in the book, high level waste decays to the same radioactivity as its "uranium ore equivalent" (I assume that means the ore needed to produce the fuel, not the same weight of ore) in about 3000 years. 10 years after discharge (the earliest date shown) it is about 10000 times as radioactive as the ore equivalent, and 100 years after discharge it is still about 3000 times as radioactive. Up to somewhat over 100 years the main emitters are cesium-137 and strontium-90. (According to Wikipedia, the cesium-137 emits both beta and gamma radiation, strontium-90 emits almost pure beta radiation.)
The book suggests that there is reason to be confident that the wastes can be contained for several hundred years, and there isn't that much of it (about 2 cubic metres per year from a typical power plant).
So, as I said at the beginning: the waste is highly radioactive for hundreds or thousands of years, but if it can be contained, nuclear plants are probably a good bet. I'd still like to see some actual measurements, rather than hand-drawn plots based on models (models aren't always right!), but the real unknown is whether the storage can actually be done successfully.
1. I've looked for measurements of the radioactivity of spent fuel rods, unsuccessfully.
2. I've had to resort to Wikipedia for the numbers I've got, which suggest to me that U-235 converts into a complex mix of fission products, which are much more radioactive than U-235 for at least several hundred years. So the spent fuel rods will also be much more radioactive for a few hundred years. (By a lesser fraction in that U-235 is a small percentage of the fuel.)
3. The containers for the fuel rods will block much of the radiation, but I have doubts that they will maintain their integrity for hundreds of years. Some of the products are gaseous, some are water soluble, there's a complex chemical mix. It's not easy to contain.
4. No country makes the nuclear plants pay for their own insurance, in all cases there are indemnity acts to put the risks onto the public, instead of the plant owner.
You claim that the wastes are safe, but you don't offer any evidence, just vague references to secret sources of information. When asked for evidence, you go the attack, claiming that because I am not satisfied with crappy Wikipedia articles, nothing would satisfy me, and because I don't have a degree in nuclear engineering, I am not qualified to ask for information.
You respond by attacking me when I ask for evidence. You tell me to look in Wikipedia, and do my own calculations.
Well, that's what I did, and it didn't reassure me. It would reassure me a lot more if there were measurements posted, rather than theoretical calculations.
So, why aren't measurements posted anywhere? There's more than 50 years of data available, it should be easy. I suspect that the measurements would contradict some of the claims from the nuclear industry, like the one parroted by Wikipedia that after 200 years the fission products are no more radioactive than uranium ore. That is clearly nonsense.
I don't know who you are or why you are such a proponent of nuclear power, but you are not convincing me. You make all sorts of claims about the safety of the waste, entirely without any support, or with the support of Wikipedia, which is self-contradictory and hardly authoritative.
Note that "natural uranium" isn't really terribly radioactive.
That's true, but several posters have claimed that within a few years used fuel decays to that level of radiation. I was assuming your "stone cold after five years" claim was one of those.
Note also that the longer the half-life, the less radioactive something is. And the shorter the half-life, the quicker it's gone. Just draw a comfortable line in the sand, and you're good to go.
Unfortunately, that line is hundreds or thousands of years out, and nobody has any experience with perfectly sealed storage of something for that long.
And note finally that fission products inside fuel rods won't emit anything outside the fuel rods but gammas
You're assuming that the fission products will stay inside the fuel rods. That might be true for several years, but it's probably not true for hundreds or thousands of years. Some of the fission products are gaseous at normal temperatures (e.g. krypton-85, a beta and gamma emitter), some are likely to be corrosive, since they won't be in stable chemical forms. They're in fairly low concentrations with standard reactors, but any of the designs that burn a significant proportion of the fuel are going to have lots of extremely radioactive and chemically active things in the mix.
Look, I'd be happy to use nuclear if the designs were seen to be safe enough to insure, and if the people running the plants had a believable way to deal with the waste. But they remind me way too much of tobacco companies in the way they hide information and mislead the public. Show me a nuclear industry web site that publishes what the radiation is from fuel rods before going in, and what it is N years after they come out. I've looked, and haven't seen one, but the sort of sloppy calculations I can do make it look as though the used fuel is about a million times worse than the unused fuel for decades after coming out, and is still thousands of times worse hundreds of years later.
This is a simple case of polluters wanting to make their pollution into an externality. The nuclear industry creates a problem when they dig up the uranium, then makes it thousands or millions of times worse when they run it through their reactors, but they want the public to deal with it.
tiny remaining radioactive bit only last 200 years.
That's not what the article you linked to says. It says that 5% of the remaining bit is strontium-90, 6% is cesium-137 (both with a 30 year half-life, so there's still 1% of them left after 200 years: but they're still a million times more radioactive than uranium at that point), 6% is technetium-99, whose 211,000 year half-life means it's essentially all there after 200 years, 5% is zirconium-93, 7% is cesium-135 (both with over million year half-lives), and there are lots of smaller components.
So, you're saying that after 5 years you've just got long half-life alpha emitters. What is the basis of this claim? Wikipedia says that you get cesium-137 (30 year half-life, beta emitter, decays to barium-137, a gamma emitter with a short half life). You also get technetium-99, a beta emitter with a 200,000 year half-life. Both of these are in non-negligible quantities, and after a couple of hundred years, they are still thousands or millions of times as radioactive as natural uranium, an alpha emitter.
That's nonsense. The "fission products" from any reactor include a complex mix of different radioactive elements, not just alpha emitters. Breeder reactors convert more of the uranium/plutonium into fission products than other reactors do, so you don't need to worry as much about leftover actinides, but you do need to worry about the lighter weight stuff.
It's hard to find solid information on this. You should not believe what any Slashdot writer (including me) writes, you should look it up in authoritative sources. Wikipedia is hardly authoritative, but even it lists lots of fission products. For example, someone pointed to this article: http://en.wikipedia.org/wiki/Integral_Fast_Reactor, which lists beta and gamma emitters making up a total of around 30% of the fission products. Some of these have a very short half-life, but about 2/3 of them have half-lives over 200,000 years.
The Wikipedia article states that "The result is that within 200 years, such wastes are no more radioactive than the ores of natural radioactive elements", but this contradicts the table of fission products.
For example, pure natural uranium has a radioactivity of around 7.1 x 10^-7 Ci/g, and presumably uranium ore is at least an order of magnitude smaller. But the Wikipedia article says that about 6% of the waste is the beta emitter technetium-99, with a half-life of around 211,000 years. The radioactivity of Tc-99 is 0.017 Ci/g, about 20,000 times higher than pure natural uranium.
There's also about 6% of beta emitter cesium-137, with a half-life of about 30 years, so after 200 years there'd be 1% of it left. But its radioactivity is 88 Ci/g, so after 200 years it would still be about a million times more radioactive than natural uranium.
The nuclear industry never publishes these numbers clearly, but you can find them if you dig a little. (The article cited by Wikipedia for the 200 year wait time does make that claim, but doesn't back it up with any numbers.)
In canada we don't have nuclear waste.... CANDU reactors use the fuel til its all gone
That's nonsense. CANDU reactors mainly burn U-238 rather than U-235, but the fission products from either one are highly radioactive and highly chemically reactive for a few thousand years. It's not the uranium in the waste that's the problem in any reactor; uranium has a very long half-life (about 4 billion years for U-238). It's the shorter half-life fission products that are the problem.
Yes, there are claims that you can safely store the waste until it decays. These are made by people who are uninsurable.
Why can't they convince the insurance companies to fully cover them? Should be a sure thing: charge large premiums, never pay out. Why do you need the Price-Anderson Nuclear Industries Indemnity Act?
Each mg of uranium that is "used up" in a nuclear plant produces fission products that are about a million times as radioactive as the original uranium (with a much shorter half-life, energy is consumed, not created). So a kWhr of electricity produces the radioactivity of a couple of kilograms of uranium, compared to a couple of milligrams produced by a coal plant.
Things aren't really that bad though, because the coal plant spews its radioactivity all around it, while the radioactive waste is usually contained within the spent fuel rods, except when the plant catches fire the way Chernobyl did.
So if there were really a reliable way in place to store spent fuel for a few thousand years while it decays, nuclear would be a clear winner. But there isn't. There are untried ways to store it, that are probably good for decades, but millenia? Not so sure.
Canada has a levy on blank media (currently just CDRs and tapes, not DVDs), and a right to make copies for personal use. (There's some question about whether allowed copies must be onto levied media, or whether they can be made copy: but it is not a copyright violation to make the private copies.)
There are lots of reasons to dislike this: you have to pay it even if you use the CDRs for data or your own music, the rules for distributing the money don't bear a close connection to what actually got copied, payments are only made to Canadian collectives, it doesn't apply to copies made on the more common media people use nowadays, etc.
The CRIA (the Canadian subsidiary of the RIAA) lobbied to have this put in place because it looked like a cash cow, but lately they've been lobbying to get rid of both it and the personal copying right. This is likely because they don't get a large share of the levy, which goes to copyright collectives first, and is distributed to their members (artists) as well as the recording companies.
It's probably not possible to fix most of the problems with the levy, but it is nice to know that I have the legal right to make copies of music, and don't have to worry about being sued over it. The Conservatives introduced legislation that kept the levy but did away with the private copying right (and promised to deal with the levy this fall, but things didn't work out for either the legislation or the promise). I think the Liberals are also in the pocket of the big media companies, so they will probably support that legislation if it ever comes to a vote.
So you should demand a blanket license to copy for personal use, not just a promise not to sue, and then this "tax" might not be such a bad thing.
Slashdot Mirror
A million dB gain is a gain of 10^100000, not 10^9. If you want to hear things at Alpha Centauri with the same signal strength as you hear things in geosynchronous orbit, your 10^26/10^6 ratio is right: you need to add 200 dB gain. I don't think you really have a whip antenna plus amplifier that gets 200 dB gain, but if you did, you'd be getting close to what you need. (Of course, you need to block the noise from Alpha Centauri, too.)
Only if they release their modified source code.
And who said they wouldn't?
So, what to do about a state that takes GPL software, modifies it, redistributes it, maybe even charges for it?
Why would you need to do anything? Those are all allowed under the GPL.
They will probably be happy to be off the Internet, because they won't get so many complaints from their constituents.
Falsely accuse businesses, especially those who are members of RIANZ.
However, this kind of service usually comes at a cost.
That's not always true, but when it is: don't put anything valuable there. If you have something valuable that you want to put online, and can't find a free host that lets you keep backups, then spend some money.
For most bloggers, it's the content of their posts that matters. They don't need byte-to-byte backup.
By valuable, I mean something that you'd like to come back to and re-use sometime in the future. Throwaways like /. posts don't need backups. Things you spend time on do.
And a corollary to the parent's good advice: if you can't easily get a complete copy of your work, find another host. Manual one-by-one downloads don't cut it.
Just checked, here's the link. One part I find particularly telling:
Make sure you deauthorize your computer before you upgrade your RAM, hard disk or other system components, or reinstall Windows. If you do not deauthorize your computer before you upgrade these components, one computer may use multiple authorizations.
One doesn't always get to choose when to change system components, sometimes they choose to fail on their own.
Apple's DRM doesn't allow you to deauthorize a machine that you don't have access to, unless you deauthorize all your machines, and you can only do that once a year.
It was Apple's DRM, as I thought would have been clear from the context.
A friend of mine complained about having the choice of pirating or re-purchasing a large collection of classical music, when his licensed system died, and he was out of allowed installs. I don't know how hard he tried to work around the problem, but in his view, it didn't always "just work".
Does MS offer a way for Google, Apple, etc. to register that they've got an update available, so they could use the standard update mechanism, instead of writing their own?
Not that Apple would choose to use it: they like to mix ads in with their updates, but I can see some other projects taking advantage of this.
Then again, I only use Firefox, and would never consider using IE.
It's harder to avoid than you seem to think. If you use Windows help to view .chm files, you're using IE. Usually they stay local, but many help files do include
links to web pages, and then you're out in the real world.
Thanks for the long post, in which you managed to include one fact, along with the insults. Too bad the fact was wrong. Uranium fuel is rarely metallic uranium (it would melt), it's usually an oxide (with a number of variations used in different reactors).
And your claim many posts ago that spent fuel emits only alpha particles was just bizarre.
So I have to wonder about your qualifications. I'd guess you're an undergrad engineering student from the way you write, but your nickname makes it look as though you're not out of high school yet.
One more followup. I found the book "Nuclear Energy in the 21st Century: World Nuclear University Press" by Ian Hore-Lacy, which actually gives some plots. I'd have preferred something more technical, but I'll take what I can get.
According to Fig 19 in the book, high level waste decays to the same radioactivity as its "uranium ore equivalent" (I assume that means the ore needed to produce the fuel, not the same weight of ore) in about 3000 years. 10 years after discharge (the earliest date shown) it is about 10000 times as radioactive as the ore equivalent, and 100 years after discharge it is still about 3000 times as radioactive. Up to somewhat over 100 years the main emitters are cesium-137 and strontium-90. (According to Wikipedia, the cesium-137 emits both beta and gamma radiation, strontium-90 emits almost pure beta radiation.)
The book suggests that there is reason to be confident that the wastes can be contained for several hundred years, and there isn't that much of it (about 2 cubic metres per year from a typical power plant).
So, as I said at the beginning: the waste is highly radioactive for hundreds or thousands of years, but if it can be contained, nuclear plants are probably a good bet. I'd still like to see some actual measurements, rather than hand-drawn plots based on models (models aren't always right!), but the real unknown is whether the storage can actually be done successfully.
Sounds like you're done, so I'll summarize:
1. I've looked for measurements of the radioactivity of spent fuel rods, unsuccessfully.
2. I've had to resort to Wikipedia for the numbers I've got, which suggest to me that U-235 converts into a complex mix of fission products, which are much more radioactive than U-235 for at least several hundred years. So the spent fuel rods will also be much more radioactive for a few hundred years. (By a lesser fraction in that U-235 is a small percentage of the fuel.)
3. The containers for the fuel rods will block much of the radiation, but I have doubts that they will maintain their integrity for hundreds of years. Some of the products are gaseous, some are water soluble, there's a complex chemical mix. It's not easy to contain.
4. No country makes the nuclear plants pay for their own insurance, in all cases there are indemnity acts to put the risks onto the public, instead of the plant owner.
You claim that the wastes are safe, but you don't offer any evidence, just vague references to secret sources of information. When asked for evidence, you go the attack, claiming that because I am not satisfied with crappy Wikipedia articles, nothing would satisfy me, and because I don't have a degree in nuclear engineering, I am not qualified to ask for information.
Thanks for the discussion.
You respond by attacking me when I ask for evidence. You tell me to look in Wikipedia, and do my own calculations.
Well, that's what I did, and it didn't reassure me. It would reassure me a lot more if there were measurements posted, rather than theoretical calculations.
So, why aren't measurements posted anywhere? There's more than 50 years of data available, it should be easy. I suspect that the measurements would contradict some of the claims from the nuclear industry, like the one parroted by Wikipedia that after 200 years the fission products are no more radioactive than uranium ore. That is clearly nonsense.
I don't know who you are or why you are such a proponent of nuclear power, but you are not convincing me. You make all sorts of claims about the safety of the waste, entirely without any support, or with the support of Wikipedia, which is self-contradictory and hardly authoritative.
Note that "natural uranium" isn't really terribly radioactive.
That's true, but several posters have claimed that within a few years used fuel decays to that level of radiation. I was assuming your "stone cold after five years" claim was one of those.
Note also that the longer the half-life, the less radioactive something is. And the shorter the half-life, the quicker it's gone. Just draw a comfortable line in the sand, and you're good to go.
Unfortunately, that line is hundreds or thousands of years out, and nobody has any experience with perfectly sealed storage of something for that long.
And note finally that fission products inside fuel rods won't emit anything outside the fuel rods but gammas
You're assuming that the fission products will stay inside the fuel rods. That might be true for several years, but it's probably not true for hundreds or thousands of years. Some of the fission products are gaseous at normal temperatures (e.g. krypton-85, a beta and gamma emitter), some are likely to be corrosive, since they won't be in stable chemical forms. They're in fairly low concentrations with standard reactors, but any of the designs that burn a significant proportion of the fuel are going to have lots of extremely radioactive and chemically active things in the mix.
Look, I'd be happy to use nuclear if the designs were seen to be safe enough to insure, and if the people running the plants had a believable way to deal with the waste. But they remind me way too much of tobacco companies in the way they hide information and mislead the public. Show me a nuclear industry web site that publishes what the radiation is from fuel rods before going in, and what it is N years after they come out. I've looked, and haven't seen one, but the sort of sloppy calculations I can do make it look as though the used fuel is about a million times worse than the unused fuel for decades after coming out, and is still thousands of times worse hundreds of years later.
This is a simple case of polluters wanting to make their pollution into an externality. The nuclear industry creates a problem when they dig up the uranium, then makes it thousands or millions of times worse when they run it through their reactors, but they want the public to deal with it.
That's nonsense. CANDU reactors mainly burn U-238 rather than U-235,
And that's nonsense too. CANDU reactors burn U-235, just in lower concentration than other kinds of reactors. It's breeder reactors that burn U-238.
tiny remaining radioactive bit only last 200 years.
That's not what the article you linked to says. It says that 5% of the remaining bit is strontium-90, 6% is cesium-137 (both with a 30 year half-life, so there's still 1% of them left after 200 years: but they're still a million times more radioactive than uranium at that point), 6% is technetium-99, whose 211,000 year half-life means it's essentially all there after 200 years, 5% is zirconium-93, 7% is cesium-135 (both with over million year half-lives), and there are lots of smaller components.
You should read articles before you cite them.
So, you're saying that after 5 years you've just got long half-life alpha emitters. What is the basis of this claim? Wikipedia says that you get cesium-137 (30 year half-life, beta emitter, decays to barium-137, a gamma emitter with a short half life). You also get technetium-99, a beta emitter with a 200,000 year half-life. Both of these are in non-negligible quantities, and after a couple of hundred years, they are still thousands or millions of times as radioactive as natural uranium, an alpha emitter.
That's nonsense. The "fission products" from any reactor include a complex mix of different radioactive elements, not just alpha emitters. Breeder reactors convert more of the uranium/plutonium into fission products than other reactors do, so you don't need to worry as much about leftover actinides, but you do need to worry about the lighter weight stuff.
It's hard to find solid information on this. You should not believe what any Slashdot writer (including me) writes, you should look it up in authoritative sources. Wikipedia is hardly authoritative, but even it lists lots of fission products. For example, someone pointed to this article: http://en.wikipedia.org/wiki/Integral_Fast_Reactor, which lists beta and gamma emitters making up a total of around 30% of the fission products. Some of these have a very short half-life, but about 2/3 of them have half-lives over 200,000 years.
The Wikipedia article states that "The result is that within 200 years, such wastes are no more radioactive than the ores of natural radioactive elements", but this contradicts the table of fission products.
For example, pure natural uranium has a radioactivity of around 7.1 x 10^-7 Ci/g, and presumably uranium ore is at least an order of magnitude smaller. But the Wikipedia article says that about 6% of the waste is the beta emitter technetium-99, with a half-life of around 211,000 years. The radioactivity of Tc-99 is 0.017 Ci/g, about 20,000 times higher than pure natural uranium.
There's also about 6% of beta emitter cesium-137, with a half-life of about 30 years, so after 200 years there'd be 1% of it left. But its radioactivity is 88 Ci/g, so after 200 years it would still be about a million times more radioactive than natural uranium.
The nuclear industry never publishes these numbers clearly, but you can find them if you dig a little. (The article cited by Wikipedia for the 200 year wait time does make that claim, but doesn't back it up with any numbers.)
In canada we don't have nuclear waste.... CANDU reactors use the fuel til its all gone
That's nonsense. CANDU reactors mainly burn U-238 rather than U-235, but the fission products from either one are highly radioactive and highly chemically reactive for a few thousand years. It's not the uranium in the waste that's the problem in any reactor; uranium has a very long half-life (about 4 billion years for U-238). It's the shorter half-life fission products that are the problem.
Yes, there are claims that you can safely store the waste until it decays. These are made by people who are uninsurable.
Why can't they convince the insurance companies to fully cover them? Should be a sure thing: charge large premiums, never pay out. Why do you need the Price-Anderson Nuclear Industries Indemnity Act?
That's a really misleading calculation.
Each mg of uranium that is "used up" in a nuclear plant produces fission products that are about a million times as radioactive as the original uranium (with a much shorter half-life, energy is consumed, not created). So a kWhr of electricity produces the radioactivity of a couple of kilograms of uranium, compared to a couple of milligrams produced by a coal plant.
Things aren't really that bad though, because the coal plant spews its radioactivity all around it, while the radioactive waste is usually contained within the spent fuel rods, except when the plant catches fire the way Chernobyl did.
So if there were really a reliable way in place to store spent fuel for a few thousand years while it decays, nuclear would be a clear winner. But there isn't. There are untried ways to store it, that are probably good for decades, but millenia? Not so sure.
Canada has a levy on blank media (currently just CDRs and tapes, not DVDs), and a right to make copies for personal use. (There's some question about whether allowed copies must be onto levied media, or whether they can be made copy: but it is not a copyright violation to make the private copies.)
There are lots of reasons to dislike this: you have to pay it even if you use the CDRs for data or your own music, the rules for distributing the money don't bear a close connection to what actually got copied, payments are only made to Canadian collectives, it doesn't apply to copies made on the more common media people use nowadays, etc.
The CRIA (the Canadian subsidiary of the RIAA) lobbied to have this put in place because it looked like a cash cow, but lately they've been lobbying to get rid of both it and the personal copying right. This is likely because they don't get a large share of the levy, which goes to copyright collectives first, and is distributed to their members (artists) as well as the recording companies.
It's probably not possible to fix most of the problems with the levy, but it is nice to know that I have the legal right to make copies of music, and don't have to worry about being sued over it. The Conservatives introduced legislation that kept the levy but did away with the private copying right (and promised to deal with the levy this fall, but things didn't work out for either the legislation or the promise). I think the Liberals are also in the pocket of the big media companies, so they will probably support that legislation if it ever comes to a vote.
So you should demand a blanket license to copy for personal use, not just a promise not to sue, and then this "tax" might not be such a bad thing.