This has got to be one of the best Slashdot posts I've ever read. Bravo. I wish I had mod points to give you, and that moderation wasn't cut off at +5.
Are you from Europe? I don't want to bring up Europe's history of subjugating other cultures for their gold and other resources. Nor do I want to ask how many "world wars" there have been, and what fraction of them occurred because Europeans couldn't get along with each other?
Which figures do you question? Most of them are easy to find. The only figures that are a little more obscure are the Ontario conservation figures following the 2003 blackout.
By the way, my post had a typo. Electricity demand in the US is growing at more than 1.5% per year, not 0.5%.
Remember Virgin's agreement to license the technology.
"London, September 27th 2004: Today, Sir Richard Branson announced that Virgin Group has entered into an agreement to license the technology to develop the world's first privately funded spaceships dedicated to carrying commercial passengers on space flights... The licensing deal with M.A.V. could be worth up to £14 million ($21.5 million) over the next fifteen years depending on the number of spaceships built by Virgin."
I didn't equate a "non-100%" solution as being worthless... that fabrication is purely your product.
Electricity demand in the US is growing at a rate greater than 0.5% per year. Diverting billions of dollars from capacity expansion to achieve a one-time 0.5% savings in energy usage doesn't make sense. That's why it is not a good plan.
The parent poster claims that conservation can't replace nuclear power. Maybe that didn't come out exactly like the poster intended, but in a sense, it's true. Nuclear accounts for ~20% of power generated in the US, 70% in France, etc. Where I live (Ontario, Canada), nuclear accounts for over 45% of electrical generating capacity.
How much can conservation displace generation? Here's an example. During recover from the 2003 blackout, extreme conservation in Ontario was able to reduce peak demand by about 5 to 10%. That was a near-emergency situation in a population well-known for being civic-minded. People here were willing to do without a lot of conveniences for a short period of time, in order to help recover from a unique situation. For the long-term, under ordinary circumstances, conservation could possibly amount to 2 to 3% of Ontario's demand.
No matter what figures you use (2-3%, or 5-10%), that doesn't even begin to approach the >45% contribution that nuclear makes to Ontario's energy mix. In that sense, conservation cannot replace nuclear. It can make a dent, but it can't replace.
In 2002, according to US Census data, there were 108.5 million occupied housing units in the US. Assume one compact fluorescent bulb per unit, with an power savings of 80 Watts per incandescent bulb replaced.
The total power savings is about 8680 megawatts (around 9 gigawatts), nationwide. However, light bulbs don't need to stay on all the time... maybe 6 hours a day. So you've saved 9 x 6 x 365 = 19710 GWh in one year. Call it 20 terawatt-hours.
In 2003, the United States generated 3848 terawatt-hours of electricity. You've saved 20 terawatt-hours with your plan. That's about 0.5% savings.
"I cannot under any circumstances accept nuclear power and genetically modified foods as a healthy alternative."
*Any* circumstances? How very dogmatic. The only difference between this guy and a hard-core, right-wing, religious fundamentalist is his choice of religious doctrine. The Greens can tolerate no dissent in these areas... dissent is heresy!
I did not go see "Fahrenheit 9/11", not because I am closed-minded, but because I did not feel like spending money to see it. I saw "Bowling for Columbine" on a free TV-movie channel, and was not impressed -- my first thought after it ended was "how did this piece of shit win an Oscar?" After that experience, anything with Michael Moore's name on it is very low on my movie-viewing (and spending) priority list.
Ugh. I hate being wrong. I re-read the article, and all the comments here, and I finally got it through my head. My conclusion: the article is okay as written, and I am an idiot.
I can't figure out *what* I was thinking earlier. I must be suffering from a lack of caffeine or something. I'm going to go remedy that right now.
Hey, I'm not confusing the meaning of nucleus, nuclei, or nucleon. Heck, I even know the difference between an isotope (same number of protons, varying mass number) and an isotone (same mass number, varying number of protons). I also know that there was no way they were going to be splitting a nucleus with a 75 eV photon... if they were able to do that, we'd have free energy forever.
What I was pointing out is that the article *did not make sense* as written. That is all.
I thought about this a little more... they say "knock both electrons out", which means it has to be a molecule of deuterium they're talking about. Still, the article is a bit confusing.
In the experiments a single photon has enough energy (75.5 electron volts) to knock both electrons out of a deuterium molecule, and the two nuclei then fly apart because
they are both positively charged.
Excuse me? A deuterium nucleus has a proton and a neutron... only one of these has a positive charge.
I haven't done any Fortran-95 in a while, but I believe that most of this syntax is correct:
Integer, Parameter:: KREL=Kind(0.0d0) Real (KREL):: X=0.0_KREL
Later on, if you want to go back and change to some other precision (single, quad??), just change the parameter statement. Also, note that if you want to use literal constants, just append "_KREL", as in "1.0_KREL".
There is a general solution. I've used it on Slackware, Mandrake, and others. Look at the manpage for ldconfig. Put old library files in a directory under/usr/lib, edit/etc/ld.so.conf, and run ldconfig.
I used to resolve this by having a directory that specifically contained old versions of library files. Try ldconfig... a snippet from the man page:
ldconfig creates the necessary links and cache (for use by the run-time linker, ld.so) to the most recent shared libraries found in the directories specified on the command line, in the file/etc/ld.so.conf, and in the trusted directories (/usr/lib and/lib). ldconfig checks the header and file names of the libraries it encounters when determining which versions should have their links updated. ldconfig ignores symbolic links when scanning for libraries...
I currently work at the Pickering CANDU station east of Toronto, but not in a design/analysis role. My previous experience is with analysis and operation of Boiling Water Reactors. I'm very interested in the Advanced CANDU (ACR-700), though. It's a sweet design.
There are several evolutionary changes in the ACR-700, relative to the previous generation CANDU-6. First, it uses fuel enriched up to 2% U-235 as opposed to natural U. Second, it retains heavy water as a moderator/reflector in the calandria, but uses light water as coolant in the primary heat transport system. Third, the fuel bundle design's been optimized to include two different pin diamaters, and the center pins are actually poisoned with dysprosium.
The end result of all those changes is that the lattice spacing of the pressure tubes, running through the calandria, has been decreased. The pitch was apparently tuned to achieve a slight, negative void coefficient.
Good point, I should have added prompt critical to the list.
Prompt critical reactor - chain reaction is self-sustaining on prompt neutrons alone
The point being that in a fission event, there are both prompt and delayed neutrons. The prompt neutrons are released immediately during fission. The delayed neutrons are released later due to radioactive decay of unstable fission products.
It is because of delayed neutrons that we are able to control the rate of fission reactions. The delay is long enough to bring the average lifetime down to controllable levels. You do not want to be critical (or supercritical) on prompt neutrons alone, otherwise power will increase at uncontrollable rates.
When achieving criticality (actually, slight supercriticality) at commercial reactors, we typically measure doubling time to determine reactor period -- how long it takes for neutron population to increase by a factor of e. You have to wait a minute or so for a stable period to be achieved. This is due to the effect of delayed neutrons.
At the BWR I worked at, we typically targeted a reactor period of 50 to 150 seconds for our startups. It's slow enough to be easily controllable, but fast enough to maintain a good, steady heatup rate.
Ah, I see now. I think you're alluding to reactivity coefficients. In the case of pebble bed, there would be a very strong negative coefficient for fuel temperature (sometimes called "doppler coefficient"), and there would be no coolant/moderator coefficients (void or temperature) to speak of since helium gas has basically no neutron interaction. So any increase in temperature would have a strong negative effect on fission rate.
It's interesting that you mentioned CANDU, then... traditional CANDU actually has a positive void coefficient, like the RBMK. It's only the newest CANDU design that has achieved a slightly negative void coefficient; actually, for that reason, the Advanced CANDU is the first CANDU that could ever be licensed in the US.
How is pebble bed not a critical reactor? Unless they're planning some kind of subcritical, accelerator-driven system, I don't see how that would be possible. It would not be consistent with anything I know of the PBMR, for instance.
Basic definitions:
Subcritical reactor - fission reaction rate is declining over time
Critical reactor - fission reaction rate is constant over time, self-sustaining chain reaction has been achieved
Supercritical reactor - fission reaction rate is increasing over time
There's nothing mystical about these terms. Every power reactor in existence goes supercritical during startup, for instance -- it's the only way you can raise power. When full power is reached, then you sit at a critical state for as long as you can. When you need to shutdown, you go subcritical. That's all there is to it.
The only way I know of to have a subcritical assembly raise power, or maintain a constant high power, is to have some external source of neutrons to drive the pile. Accelerator driven systems would have the advantage of always being subcritical, all you'd have to do to shutdown is shut off the accelerator. The problem right now is the high amount of power needed to run the accelerator constantly. Right now, and for the near future, critical reactors are going to be much more efficient.
So really, what are you talking about? Nobody is going to build a subcritical accelerator driven system in the near future. Pebble beds, at least in the form of the PBMR, are critical reactors. Where are you getting your information?
I have no qualms with people putting themselves at risk. It's when their actions start adding to others' risk that regulation comes into play. Allowing an essentially unproven, non-standard vehicle onto a public highway is what I'm concerned about.
Slashdot Mirror
A nice article on retro-causation:
a rds/
http://plato.stanford.edu/entries/causation-backw
This has got to be one of the best Slashdot posts I've ever read. Bravo. I wish I had mod points to give you, and that moderation wasn't cut off at +5.
Are you from Europe? I don't want to bring up Europe's history of subjugating other cultures for their gold and other resources. Nor do I want to ask how many "world wars" there have been, and what fraction of them occurred because Europeans couldn't get along with each other?
No offense. Just my 0.02USD
Which figures do you question? Most of them are easy to find. The only figures that are a little more obscure are the Ontario conservation figures following the 2003 blackout.
By the way, my post had a typo. Electricity demand in the US is growing at more than 1.5% per year, not 0.5%.
Now *that's* funny!
Remember Virgin's agreement to license the technology.
l ed_paul_allen_virgin_galactic.htm
"London, September 27th 2004: Today, Sir Richard Branson announced that Virgin Group has entered into an agreement to license the technology to develop the world's first privately funded spaceships dedicated to carrying commercial passengers on space flights... The licensing deal with M.A.V. could be worth up to £14 million ($21.5 million) over the next fifteen years depending on the number of spaceships built by Virgin."
http://www.scaled.com/projects/tierone/092704_sca
I didn't equate a "non-100%" solution as being worthless... that fabrication is purely your product.
Electricity demand in the US is growing at a rate greater than 0.5% per year. Diverting billions of dollars from capacity expansion to achieve a one-time 0.5% savings in energy usage doesn't make sense. That's why it is not a good plan.
The parent poster claims that conservation can't replace nuclear power. Maybe that didn't come out exactly like the poster intended, but in a sense, it's true. Nuclear accounts for ~20% of power generated in the US, 70% in France, etc. Where I live (Ontario, Canada), nuclear accounts for over 45% of electrical generating capacity.
How much can conservation displace generation? Here's an example. During recover from the 2003 blackout, extreme conservation in Ontario was able to reduce peak demand by about 5 to 10%. That was a near-emergency situation in a population well-known for being civic-minded. People here were willing to do without a lot of conveniences for a short period of time, in order to help recover from a unique situation. For the long-term, under ordinary circumstances, conservation could possibly amount to 2 to 3% of Ontario's demand.
No matter what figures you use (2-3%, or 5-10%), that doesn't even begin to approach the >45% contribution that nuclear makes to Ontario's energy mix. In that sense, conservation cannot replace nuclear. It can make a dent, but it can't replace.
In 2002, according to US Census data, there were 108.5 million occupied housing units in the US. Assume one compact fluorescent bulb per unit, with an power savings of 80 Watts per incandescent bulb replaced.
The total power savings is about 8680 megawatts (around 9 gigawatts), nationwide. However, light bulbs don't need to stay on all the time... maybe 6 hours a day. So you've saved 9 x 6 x 365 = 19710 GWh in one year. Call it 20 terawatt-hours.
In 2003, the United States generated 3848 terawatt-hours of electricity. You've saved 20 terawatt-hours with your plan. That's about 0.5% savings.
Yeah, that's a great plan.
"I cannot under any circumstances accept nuclear power and genetically modified foods as a healthy alternative."
*Any* circumstances? How very dogmatic. The only difference between this guy and a hard-core, right-wing, religious fundamentalist is his choice of religious doctrine. The Greens can tolerate no dissent in these areas... dissent is heresy!
I did not go see "Fahrenheit 9/11", not because I am closed-minded, but because I did not feel like spending money to see it. I saw "Bowling for Columbine" on a free TV-movie channel, and was not impressed -- my first thought after it ended was "how did this piece of shit win an Oscar?" After that experience, anything with Michael Moore's name on it is very low on my movie-viewing (and spending) priority list.
I get pretty good results with this. It seems the keys to good results are:
- use your postal code for the location
- limit the geographic range to within 2, 10, 25 km, etc.
- add area code to your search phrase to refine results if the above don't help.
A couple more interesting tidbits:Overall, I'm pretty happy with this. I've found quite a few things close to home that I didn't know about previously.
Ugh. I hate being wrong. I re-read the article, and all the comments here, and I finally got it through my head. My conclusion: the article is okay as written, and I am an idiot.
I can't figure out *what* I was thinking earlier. I must be suffering from a lack of caffeine or something. I'm going to go remedy that right now.
Thank you for being a witness to my idiocy.
Hey, I'm not confusing the meaning of nucleus, nuclei, or nucleon. Heck, I even know the difference between an isotope (same number of protons, varying mass number) and an isotone (same mass number, varying number of protons). I also know that there was no way they were going to be splitting a nucleus with a 75 eV photon... if they were able to do that, we'd have free energy forever.
What I was pointing out is that the article *did not make sense* as written. That is all.
I thought about this a little more... they say "knock both electrons out", which means it has to be a molecule of deuterium they're talking about. Still, the article is a bit confusing.
Even weirder is this statement:
Excuse me? A deuterium nucleus has a proton and a neutron... only one of these has a positive charge.
And to see why so many people stick with Fortran, and why Fortran needs to live on, see http://www.fortranstatement.com/Site/responses.htm l at the same site.
I haven't done any Fortran-95 in a while, but I believe that most of this syntax is correct:
Later on, if you want to go back and change to some other precision (single, quad??), just change the parameter statement. Also, note that if you want to use literal constants, just append "_KREL", as in "1.0_KREL".
First post?
There is a general solution. I've used it on Slackware, Mandrake, and others. Look at the manpage for ldconfig. Put old library files in a directory under /usr/lib, edit /etc/ld.so.conf, and run ldconfig.
I used to resolve this by having a directory that specifically contained old versions of library files. Try ldconfig... a snippet from the man page:
ldconfig creates the necessary links and cache (for use by the run-time linker, ld.so) to the most recent shared libraries found in the directories specified on the command line, in the file /etc/ld.so.conf, and in the trusted directories (/usr/lib and /lib). ldconfig checks the header and file names of the libraries it encounters when determining which versions should have their links updated. ldconfig ignores symbolic links when scanning for libraries...
I currently work at the Pickering CANDU station east of Toronto, but not in a design/analysis role. My previous experience is with analysis and operation of Boiling Water Reactors. I'm very interested in the Advanced CANDU (ACR-700), though. It's a sweet design.
- reviews/design-cert/acr-700.html
There are several evolutionary changes in the ACR-700, relative to the previous generation CANDU-6. First, it uses fuel enriched up to 2% U-235 as opposed to natural U. Second, it retains heavy water as a moderator/reflector in the calandria, but uses light water as coolant in the primary heat transport system. Third, the fuel bundle design's been optimized to include two different pin diamaters, and the center pins are actually poisoned with dysprosium.
The end result of all those changes is that the lattice spacing of the pressure tubes, running through the calandria, has been decreased. The pitch was apparently tuned to achieve a slight, negative void coefficient.
The canonical site for ACR-700 information is http://www.aecl.ca/
You can find a lot of other info at:
http://www.nrc.gov/reactors/new-licensing/license
Scroll down to the bottom, and you'll see a link for other Pre-application documents. That's where you want to go for more technical info.
Good point, I should have added prompt critical to the list.
Prompt critical reactor - chain reaction is self-sustaining on prompt neutrons alone
The point being that in a fission event, there are both prompt and delayed neutrons. The prompt neutrons are released immediately during fission. The delayed neutrons are released later due to radioactive decay of unstable fission products.
It is because of delayed neutrons that we are able to control the rate of fission reactions. The delay is long enough to bring the average lifetime down to controllable levels. You do not want to be critical (or supercritical) on prompt neutrons alone, otherwise power will increase at uncontrollable rates.
When achieving criticality (actually, slight supercriticality) at commercial reactors, we typically measure doubling time to determine reactor period -- how long it takes for neutron population to increase by a factor of e. You have to wait a minute or so for a stable period to be achieved. This is due to the effect of delayed neutrons.
At the BWR I worked at, we typically targeted a reactor period of 50 to 150 seconds for our startups. It's slow enough to be easily controllable, but fast enough to maintain a good, steady heatup rate.
Ah, I see now. I think you're alluding to reactivity coefficients. In the case of pebble bed, there would be a very strong negative coefficient for fuel temperature (sometimes called "doppler coefficient"), and there would be no coolant/moderator coefficients (void or temperature) to speak of since helium gas has basically no neutron interaction. So any increase in temperature would have a strong negative effect on fission rate.
It's interesting that you mentioned CANDU, then... traditional CANDU actually has a positive void coefficient, like the RBMK. It's only the newest CANDU design that has achieved a slightly negative void coefficient; actually, for that reason, the Advanced CANDU is the first CANDU that could ever be licensed in the US.
How is pebble bed not a critical reactor? Unless they're planning some kind of subcritical, accelerator-driven system, I don't see how that would be possible. It would not be consistent with anything I know of the PBMR, for instance.
Basic definitions:
Subcritical reactor - fission reaction rate is declining over time
Critical reactor - fission reaction rate is constant over time, self-sustaining chain reaction has been achieved
Supercritical reactor - fission reaction rate is increasing over time
There's nothing mystical about these terms. Every power reactor in existence goes supercritical during startup, for instance -- it's the only way you can raise power. When full power is reached, then you sit at a critical state for as long as you can. When you need to shutdown, you go subcritical. That's all there is to it.
The only way I know of to have a subcritical assembly raise power, or maintain a constant high power, is to have some external source of neutrons to drive the pile. Accelerator driven systems would have the advantage of always being subcritical, all you'd have to do to shutdown is shut off the accelerator. The problem right now is the high amount of power needed to run the accelerator constantly. Right now, and for the near future, critical reactors are going to be much more efficient.
So really, what are you talking about? Nobody is going to build a subcritical accelerator driven system in the near future. Pebble beds, at least in the form of the PBMR, are critical reactors. Where are you getting your information?
I have no qualms with people putting themselves at risk. It's when their actions start adding to others' risk that regulation comes into play. Allowing an essentially unproven, non-standard vehicle onto a public highway is what I'm concerned about.