Beta particles (electrons ejected from the nucleus, basically) have a mean free path of about a foot in air. Place anything else in between, like a thin sheet of aluminum or a little bit of plastic, and it sucks up the betas real quick.
The other big problem is that gammas are quantized, beta particles are not. When something radioactively decays, it gives off gamma rays of distinct, unique energies -- very useful for determining the radioactive isotope you're looking at. Not so for betas; they're emitted over a wide range of energies, and it can be very difficult (but not impossible) to tell what you're looking at by betas alone.
I don't mean to downplay what this accomplishes, in a nice, small form factor. But this doesn't revolutionize the world of radiation detection. To date, no one has really been crying for a combined, digital, gamma and beta detector. Maybe if you build it, they will come, but I don't see a large market for this.
Yes, if it were pigeons, it would be deemed airborne radiation, meaning everyone in the area would have to get fitted with respirators, hoods, and full-body anti-contamination suits.
For a truly *great* read about what PARC was like, I would highly recommend "Dealers of Lightning" by Michael Hiltzik.
The book goes into some detail about the environment, the management style (both local and at "HQ" back in NY state), and all the great inventions that came out of there. And also of PARC's decline in the mid-to-late 1980's. I really wish I could have been a fly on the wall back in those days, and this book gets pretty close.
Less than twelve bucks from Amazon and well worth it.
If you didn't like the dynamo for your bike, you're definitely not going to like the in-boot charger. Thermopiles have notoriously hideous efficiencies, like 2-5%.
Note also that it relies on a heat difference between your foot and whatever is outside. So on a hot day, you're going to have a hard time generating much of a delta-T, and your efficiency will drop even further.
Despite the fact that my nickname is one of these devices, I'm not very hopeful. A piezo-electric based device that uses the mechanical motion of your heel striking the ground is a much better solution, IMHO.
A more fun way to play is to have the list of 2 letter words printed out and available to everyone.
Here is a sample but there are many others on the internet. Use The Google.
The cool thing about this is that it levels the playing field for all, AND it expands the board by allowing you to make neat plays that you might not otherwise have been able to.
Wholeheartedly agree. Just ask Martha Stewart. She sold $230,000 worth of ImClone stock one day before the stock value crashed, to avoid losses of $45,000. In the grand scheme of things, $45k isn't a whole lot to either Martha Stewart, ImClone, or the Securities and Exchange Commission.
But for the *coverup*, she got 5 months in jail and 5 months in home confinement.
Don't worry, I read the summary. I neglected to account for slack-jawed troglodytes like yourself trying to pass themselves off as nuclear engineers. My bad.
Nuclear instruments, like those sold by GE Reuter Stokes and LND detect neutrons -- they infer the power of a reactor by measuring how many neutrons leak out of the reactor core. (They are calibrated by comparing the analog readout under a known power condition... say, by the flow meters going into a turbine, in a process called a calorimetric.) The DHS detectors mentioned in the article have neutron detectors in them that use He-3 to do the neutron detection.
However, the false alarms alluded to in the summary are not due to neutrons; the false alarms stem from gamma rays, another form of radiation. Coffee beans, kitty litter, ceramics, bananas, and all the other sources of Naturally Occurring Radioactive Material emit gamma rays. The equipment mentioned in the summary also has gamma ray sensors, which occasionally produce an alarm on things like kitty litter. I assure you, if one were to drive a truck full of kitty litter through the containment building of a nuclear reactor, the instrumentation would be completely unaffected. The NRC regulators might look at you funny, though.
Admittedly, the summary (and most of the linked articles) did not draw the distinction very well between the gamma detectors (i.e., the source of the false alarms on the older detectors) and the neutron detectors (based on He-3, which is going away). Hope this clears things up.
PS - in the future, I will research my Linux distributions better before making bad analogies on Slashdot. whoops.
Boron-10 lined proportional counters, fission chambers, boron trifluoride, lithium doped glass... there are lots of other options out there. None of them may have quite the same sensitivity, but you can just pack more sensors in to overcome sensitivity.
To make a slashdot analogy, it's kind of like if all Debian developers caught swine flu and perished. Not a big deal, just move over to Ubuntu or Fedora.
If it sounds like what I think it's going to sound like, I sure hope you can turn the sound off. This youtube link appears to be what the Spinners sound like. Ick; it's cheesy electro-techno.
I mean, seriously, a "whooshing" sound would be more credible. A soundtrack is too garish.
The whole reason the Space Transportation System (STS, or just "space shuttle") looks the way it does is entirely due to now-defunct military requirements. When they were designing the shuttle, the DoD had a requirement to be able to place a payload in polar orbit and return to Earth in one orbit, in order to "secretly" deploy spy satellites. This is hard. No, really, this is very hard. The earth is spinning "sideways" and it takes a tremendous amount of impulse (read: fuel) to change your orbit from sideways to vertical. Then you have to land again.
NASA, dutiful organization that it was, came up with the idea of "tacking" the orbiter on the side. And they gave it wings. This was the only way they could get the crew-carrying module to safely glide back to its original destination.
About 5 years into the design, the DoD said, "No, thanks, we don't want that system anymore," and left NASA holding the bag. So, we're stuck with this design where the re-entry surface is exposed to the outside during launch (nobody else does that). The engines on the orbiter remain the highest energy-dense engines ever developed.
Nah, I don't think the Chinese government actually believes they can go through with this. This is a bluff; a giant bargaining chip. Start out asking for something untenable, then in negotiations, trim your requirements back until you end up with something that's only a very good deal.
China is the world's largest importer of raw materials, and the world's largest exporter of finished goods. As they nation (and economy) grows, China needs to ensure that it has good access to those finished goods that it cannot make in-house. I suspect, by May of next year (when the "source code" thing is supposed to be implemented), China will have secured trade agreements with Japan, the US, S. Korea, and everybody else it cares about, guaranteeing a certain level of fancy high-end electronics with a low tariff.
China's not stupid. With a growing market of 1.3B people, it can threaten to do something insane, and other countries have no choice but to offer great deals to pacify the Chinese Tiger.
Most expensive science experiment ever?
on
LHC Flips On Tomorrow
·
· Score: 3, Informative
Look, I think the LHC is really cool -- and I'm looking forward to the results it produces -- but I'm afraid it's not the most expensive science project.
The International Space Station gets that (dis)honor, with an estimated cost of $25.6B (US) from 1994 to 2005, not including shuttle costs - and that's just NASA's budget.
So, from that perspective, the LHC is a bargain. And it's probably still cheap compared to what the Superconducting SuperCollider would have ended up costing.
I made the switch from AltaVista to Google when I discovered Google would consistently return pretty much what I was looking for on the first page. That was early 1999. Then they added USENET? Never looked back since.
Others have already answered your direct questions pretty well, so I won't go into that.
But the fact is, we do a fair amount of radiation scanning at all border crossings and seaports into the United States. And they go "false positive" all the time: kitty litter, ceiling tile, some welding rods, ceramics... you'd be very surprised at how much natural radiation is out there. I think it's a little under 5% of all cargo is detectably above the background level.
Medical patients are screaming hot, and they alarm all the time. Pity the poor truck driver who has a regular route between Vancouver and Seattle, and just got a Tc-99m stress test... he will ring off the detectors every time for the next two weeks. Lucky for him, most hospitals give you a card that says, "Yes, I'm radioactive; I just got a medical treatment." It happens fairly often now, so it doesn't make local news. But the cat is pretty funny, so it makes the news, I guess.
Nah; unfortunately, wikileaks shouldn't get the credit for this photo. To my knowledge, it was first published by the nuclear weapon archive on 23 August 2007.
Information like this comes from the dedication of researchers like Carey Sublette, Richard Rhodes, and Chuck Hansen. Their books & publications make for fascinating reading. Calculating the damage done as a result of these publications is an exercise left to the reader.
Graphite rods, held by fail-safe hair-trigger mechanisms, can be slammed into place, shutting down a reactor quickly. Almost. The control and safety rods are usually boron, cadmium, hafnium, or some combination thereof. Graphite is a moderator with a very low cross section for absorption of neutrons, and would likely increase reactor power. And "hair-trigger" is a little melodramatic... they're usually pneumatic or magnetically held in place via solenoid, and when the power is lost to the solenoid, the rod drops. The events needed to cause a scram are pretty well thought out in advance.
Although I've never worked on one, I understand that sodium reactors are a real bear to manage. The US Navy tried it once on the USS Seawolf, but opted for plain-old-water. Some of the reasons were:
1.) The 15 hour half-life of Na-24 prevented immediate entry to the reactor in case of repair. Five half lives (the standard assumed for total decay away) means you're cooling your heels for about three days before you can really do any work. It makes quick response - like the kind Monju would have liked to have done - very difficult, if not impossible. 2.) Sodium freezes at 208F (almost 100C). Freezing in the pipes can be very bad for decay heat removal, as well as putting undue stresses on the pipes. I have seen previously rectangular "pipes" get their sides sucked in when the sodium freezes - which is impressive because they were 1/8-inch thick metal walls. Hence, you have to keep the sodium hot to work on it.
Neither of the above are necessarily deal-killers, particularly for land-based reactors. Yes, you can work around the 15 hour half life of the sodium, but it sure makes reactor entry challenging in times of distress.
Radionuclides give off unique spectral signatures. I-131 looks different from Tc-99m (another common medical isotope) which looks different from cobalt-60 (an industrial isotope) which looks different from uranium. I imagine they're using small wafers of cadmium-zinc-telluride (CZT), which has the ability to do this spectral segregation, but TFA didn't say. Does anyone know?
Having it determine what isotope it's looking at would drastically reduce the number of false hits you might get. It probably WOULDN'T alarm on that truck of bananas... or that medical patient you're standing next to who's lit up like a light bulb full of iodine. CZT has a pretty poor collection efficiency -- it's very small and it certainly doesn't stop every piece of radiation you throw at it -- but it looks like they're trying sheer numbers (millions of cell phones) to overcome that.
My question is, what does this do to battery life? It takes energy to power up the CZT crystal, and all the necessary electronics (multichannel analyzer, preamplifier, HV supply, etc.). That's a cost most consumers aren't willing to put up with.
Well spoke; I agree completely that the utility of Executive Privilege does not apply in this case for any reason - they're not executive and, in this case, they don't have any privilege.
In a similar vein, this quote really got under my skin:
EPA is concerned about the chilling effect that would occur if agency employees believed their frank and honest opinions and analysis expressed as part of assessing California's waiver request were to be disclosed in a broad setting I've worked in and for the government for almost a decade. In no instance can I EVER think of a situation when I would not have wanted my deliberations to have gone public, except for security reasons. Decent, respectful humans with a few shreds of integrity should always be trying to base their opinions & decisions on FACTS that should be as ironclad as possible. If there are drawbacks / uncertainties / limitations, that's fine; just document them and show how you're dealing with them as best as possible. The suggestion that publicly disclosing those discussions would have a "chilling effect" is, in itself, chilling. What conversations ARE they having behind closed doors? And what on earth is going on that they need to protect?
As Hamlet once said, "Methinks thou dost protest too much."
No, actually, I think the martians are behind this. See, they're upset by the recent spate of successes in the Expensive Hardware Lob contest and are now doing everything they can to even the score.
Here's hoping that Spirit and Opportunity know how to duck and cover effectively...
I normally wouldn't justify it with a response, but those comments really got my goat.
1. In asserting I was off by a factor of four, you have proven my order-of-magnitude guesstimate.
2a. Although I'm pretty sure I've done more nuclear engineering design work than you ever will, I don't actually know the chemical properties of UH3. We nuclear engineers try pretty darned hard to keep our uranium from hydriding in the first place. It reacts violently with water. UO2 or UC is much more stable. Please explain why the chemical properties are so relevant in rejecting about 20MW of heat. Neither TFA nor the hyperionpowergeneration.com page gave any technical insight.
2b. "Your statements about cooling are groundless." Again, basic thermodynamics state that the heat must either be rejected somewhere, or the system will heat up. The heat must go somewhere. I just don't see why my statement is groundless.
So, at first I was annoyed, but maybe we can turn this into an educational experience. What's so great about UH3?
Slashdot Mirror
Beta particles (electrons ejected from the nucleus, basically) have a mean free path of about a foot in air. Place anything else in between, like a thin sheet of aluminum or a little bit of plastic, and it sucks up the betas real quick.
The other big problem is that gammas are quantized, beta particles are not. When something radioactively decays, it gives off gamma rays of distinct, unique energies -- very useful for determining the radioactive isotope you're looking at. Not so for betas; they're emitted over a wide range of energies, and it can be very difficult (but not impossible) to tell what you're looking at by betas alone. I don't mean to downplay what this accomplishes, in a nice, small form factor. But this doesn't revolutionize the world of radiation detection. To date, no one has really been crying for a combined, digital, gamma and beta detector. Maybe if you build it, they will come, but I don't see a large market for this.
Silly rabbit, radiation is for RADCON.
Then, what can we call the alliance between Samsung, Hitachi, Intel, and Toshiba? I'm sure someone out there can come up with a creative acronym.
I'll start. How about "THIS"?
The book goes into some detail about the environment, the management style (both local and at "HQ" back in NY state), and all the great inventions that came out of there. And also of PARC's decline in the mid-to-late 1980's. I really wish I could have been a fly on the wall back in those days, and this book gets pretty close.
Less than twelve bucks from Amazon and well worth it.
From the zoomed-out scale, and for non-techies: The lower right corner, just a little lower and further to the right than the Twitter icon.
Why does this remind me of cup stacking?
Note also that it relies on a heat difference between your foot and whatever is outside. So on a hot day, you're going to have a hard time generating much of a delta-T, and your efficiency will drop even further.
Despite the fact that my nickname is one of these devices, I'm not very hopeful. A piezo-electric based device that uses the mechanical motion of your heel striking the ground is a much better solution, IMHO.
Here is a sample but there are many others on the internet. Use The Google.
The cool thing about this is that it levels the playing field for all, AND it expands the board by allowing you to make neat plays that you might not otherwise have been able to.
But for the *coverup*, she got 5 months in jail and 5 months in home confinement.
Similar story here, I think. I totally agree that the actual damages are minor. For a very good description of just how freaking minor this is, see this great description by Rod Adams of Atomic Insights.
It is an utter shame that gigawatts of carbon-free electricity are likely to be taken off the grid because of this incident.
Don't worry, I read the summary. I neglected to account for slack-jawed troglodytes like yourself trying to pass themselves off as nuclear engineers. My bad.
... say, by the flow meters going into a turbine, in a process called a calorimetric.) The DHS detectors mentioned in the article have neutron detectors in them that use He-3 to do the neutron detection.
Nuclear instruments, like those sold by GE Reuter Stokes and LND detect neutrons -- they infer the power of a reactor by measuring how many neutrons leak out of the reactor core. (They are calibrated by comparing the analog readout under a known power condition
However, the false alarms alluded to in the summary are not due to neutrons; the false alarms stem from gamma rays, another form of radiation. Coffee beans, kitty litter, ceramics, bananas, and all the other sources of Naturally Occurring Radioactive Material emit gamma rays. The equipment mentioned in the summary also has gamma ray sensors, which occasionally produce an alarm on things like kitty litter. I assure you, if one were to drive a truck full of kitty litter through the containment building of a nuclear reactor, the instrumentation would be completely unaffected. The NRC regulators might look at you funny, though.
Admittedly, the summary (and most of the linked articles) did not draw the distinction very well between the gamma detectors (i.e., the source of the false alarms on the older detectors) and the neutron detectors (based on He-3, which is going away). Hope this clears things up.
PS - in the future, I will research my Linux distributions better before making bad analogies on Slashdot. whoops.
There are other neutron detection technologies out there. Commercial nuclear power reactors have used other technologies for years.
... there are lots of other options out there. None of them may have quite the same sensitivity, but you can just pack more sensors in to overcome sensitivity.
Boron-10 lined proportional counters, fission chambers, boron trifluoride, lithium doped glass
To make a slashdot analogy, it's kind of like if all Debian developers caught swine flu and perished. Not a big deal, just move over to Ubuntu or Fedora.
I mean, seriously, a "whooshing" sound would be more credible. A soundtrack is too garish.
The whole reason the Space Transportation System (STS, or just "space shuttle") looks the way it does is entirely due to now-defunct military requirements. When they were designing the shuttle, the DoD had a requirement to be able to place a payload in polar orbit and return to Earth in one orbit, in order to "secretly" deploy spy satellites. This is hard. No, really, this is very hard. The earth is spinning "sideways" and it takes a tremendous amount of impulse (read: fuel) to change your orbit from sideways to vertical. Then you have to land again.
NASA, dutiful organization that it was, came up with the idea of "tacking" the orbiter on the side. And they gave it wings. This was the only way they could get the crew-carrying module to safely glide back to its original destination.
About 5 years into the design, the DoD said, "No, thanks, we don't want that system anymore," and left NASA holding the bag. So, we're stuck with this design where the re-entry surface is exposed to the outside during launch (nobody else does that). The engines on the orbiter remain the highest energy-dense engines ever developed.
For more trivia, see here.
A quick grep shows that it's not. "phyllophyllin" gets that honor.
The Google tells me it's a bluish-red [purple??!?] acid derived from chlorophyll.
China is the world's largest importer of raw materials, and the world's largest exporter of finished goods. As they nation (and economy) grows, China needs to ensure that it has good access to those finished goods that it cannot make in-house. I suspect, by May of next year (when the "source code" thing is supposed to be implemented), China will have secured trade agreements with Japan, the US, S. Korea, and everybody else it cares about, guaranteeing a certain level of fancy high-end electronics with a low tariff.
China's not stupid. With a growing market of 1.3B people, it can threaten to do something insane, and other countries have no choice but to offer great deals to pacify the Chinese Tiger.
The International Space Station gets that (dis)honor, with an estimated cost of $25.6B (US) from 1994 to 2005, not including shuttle costs - and that's just NASA's budget.
So, from that perspective, the LHC is a bargain. And it's probably still cheap compared to what the Superconducting SuperCollider would have ended up costing.
I made the switch from AltaVista to Google when I discovered Google would consistently return pretty much what I was looking for on the first page. That was early 1999. Then they added USENET? Never looked back since.
But the fact is, we do a fair amount of radiation scanning at all border crossings and seaports into the United States. And they go "false positive" all the time: kitty litter, ceiling tile, some welding rods, ceramics ... you'd be very surprised at how much natural radiation is out there. I think it's a little under 5% of all cargo is detectably above the background level.
Medical patients are screaming hot, and they alarm all the time. Pity the poor truck driver who has a regular route between Vancouver and Seattle, and just got a Tc-99m stress test ... he will ring off the detectors every time for the next two weeks. Lucky for him, most hospitals give you a card that says, "Yes, I'm radioactive; I just got a medical treatment." It happens fairly often now, so it doesn't make local news. But the cat is pretty funny, so it makes the news, I guess.
See also here.
Click here for the full story and picture.
Information like this comes from the dedication of researchers like Carey Sublette, Richard Rhodes, and Chuck Hansen. Their books & publications make for fascinating reading. Calculating the damage done as a result of these publications is an exercise left to the reader.
1.) The 15 hour half-life of Na-24 prevented immediate entry to the reactor in case of repair. Five half lives (the standard assumed for total decay away) means you're cooling your heels for about three days before you can really do any work. It makes quick response - like the kind Monju would have liked to have done - very difficult, if not impossible. 2.) Sodium freezes at 208F (almost 100C). Freezing in the pipes can be very bad for decay heat removal, as well as putting undue stresses on the pipes. I have seen previously rectangular "pipes" get their sides sucked in when the sodium freezes - which is impressive because they were 1/8-inch thick metal walls. Hence, you have to keep the sodium hot to work on it.
Neither of the above are necessarily deal-killers, particularly for land-based reactors. Yes, you can work around the 15 hour half life of the sodium, but it sure makes reactor entry challenging in times of distress.
Having it determine what isotope it's looking at would drastically reduce the number of false hits you might get. It probably WOULDN'T alarm on that truck of bananas ... or that medical patient you're standing next to who's lit up like a light bulb full of iodine. CZT has a pretty poor collection efficiency -- it's very small and it certainly doesn't stop every piece of radiation you throw at it -- but it looks like they're trying sheer numbers (millions of cell phones) to overcome that.
My question is, what does this do to battery life? It takes energy to power up the CZT crystal, and all the necessary electronics (multichannel analyzer, preamplifier, HV supply, etc.). That's a cost most consumers aren't willing to put up with.
In a similar vein, this quote really got under my skin:
EPA is concerned about the chilling effect that would occur if agency employees believed their frank and honest opinions and analysis expressed as part of assessing California's waiver request were to be disclosed in a broad setting I've worked in and for the government for almost a decade. In no instance can I EVER think of a situation when I would not have wanted my deliberations to have gone public, except for security reasons. Decent, respectful humans with a few shreds of integrity should always be trying to base their opinions & decisions on FACTS that should be as ironclad as possible. If there are drawbacks / uncertainties / limitations, that's fine; just document them and show how you're dealing with them as best as possible. The suggestion that publicly disclosing those discussions would have a "chilling effect" is, in itself, chilling. What conversations ARE they having behind closed doors? And what on earth is going on that they need to protect?As Hamlet once said, "Methinks thou dost protest too much."
Here's hoping that Spirit and Opportunity know how to duck and cover effectively...
1. In asserting I was off by a factor of four, you have proven my order-of-magnitude guesstimate.
2a. Although I'm pretty sure I've done more nuclear engineering design work than you ever will, I don't actually know the chemical properties of UH3. We nuclear engineers try pretty darned hard to keep our uranium from hydriding in the first place. It reacts violently with water. UO2 or UC is much more stable. Please explain why the chemical properties are so relevant in rejecting about 20MW of heat. Neither TFA nor the hyperionpowergeneration.com page gave any technical insight.
2b. "Your statements about cooling are groundless." Again, basic thermodynamics state that the heat must either be rejected somewhere, or the system will heat up. The heat must go somewhere. I just don't see why my statement is groundless.
So, at first I was annoyed, but maybe we can turn this into an educational experience. What's so great about UH3?