Antineutrino Device Tackles Nuclear Proliferation

KentuckyFC writes "One of the biggest problems in nuclear proliferation is verifying that countries are not secretly transferring fissile material by taking it out of reactors and selling it. Now a group of US scientists say they've developed a machine that can remotely detect whether a reactor has been switched on and off by detecting the antineutrinos produced by nuclear reactions. The detector is about the size of a car engine and is designed to be left near a reactor to record data. The group has been testing a prototype at the San Onofre Nuclear Generating Station in Southern California and says it works well (abstract). Now it's up to the International Atomic Energy Authority in Vienna to decide whether to deploy the new machine."

Comments

Detecting (anti)neutrinos?

[clonan]

I was under the impression that neutrinos, anti or otherwise are extremly difficult to detect...

Does anyone have a link that suggests anything different?

Re:Detecting (anti)neutrinos?

[jpflip]

They are extremely difficult to detect, but not impossible. Moreover, nuclear reactors produce quite a lot of them.

As a recent example, the KamLAND neutrino experiment (http://kamland.lbl.gov/) used a 1000 ton detector in Japan to study the flux of neutrinos emitted from dozens of reactors in Japan and Korea, some hundreds of miles away. KamLAND performed precision studies of the propagation of neutrinos over distance, and was also able to detect the rising and falling neutrino fluxes as various reactors powered up and down.

The detection device described in the article is much smaller, but it's located much closer to the reactor. I've heard talks on this, and it seems quite reasonable.

Re:Detecting (anti)neutrinos?

[JustinOpinion]

The neutrino interaction is indeed very weak, so they are difficult to detect. A major problem is that the other sources (cosmic rays, ambient radiation) can give false positives.

However the proposal is to place the device rather near to a nuclear reactor. A reactor generates enough flux that big detectors can measure the neutrino flux from miles away. So a small (and probably less shielded) detector that is much closer (<100 m) will receive enough flux to get statistically significant data.

The preprint says:

For example, cubic meter scale hydrogenous scintillator detectors, containing 10^28 target protons Np, will register thousands of interactions per day at standoff distances of 10-50 meters from typical commercial nuclear reactors. The proposal thus requires the detector to be installed on-site at the nuclear reactor. You may wonder "Is this actually useful for monitoring, then? If someone wants to lie about their reactor usage and burn rate, they will just falsify the detector records, too." Well, the idea is that this local detector is completely independent from the reactor (it doesn't rely on sensors hooked into the reactor, for instance). Thus it can be locked and sealed off completely; installed and managed by a completely independent oversight organization.

Re:Detecting (anti)neutrinos?

[wile_e_wonka]

I was under the impression that neutrinos, anti or otherwise are extremly difficult to detect... I think that is why this is news, and why this wasn't solved years ago. I don't think you'l find any links saying that neutrinos or antineutrinos are easy to detect. But for one suggesting that they are possible to detect after years of research and innovation, see the links in the summary, above.

Re:Detecting (anti)neutrinos?

[Martin Blank]

The neutrino interaction is indeed very weak, so they are difficult to detect. A major problem is that the other sources (cosmic rays, ambient radiation) can give false positives.

Would this prevent the use of such detectors in satellites? I realize that this first design requires that it be essentially next to the reactor, and that its time resolution is far too short for common orbits. But would there be too much interference in space for this to ever be of practical use?

Re:Detecting (anti)neutrinos?

[Tenebrousedge]

Yeah, and then you just need a secure channel for that data to travel on. What were you thinking of for that? Hooking it into an internet connection? Specialized data link of some sort? Have a technician come download logs every once in a while? Your task is to come up with something that a (presumeably governmental) body with the resources to operate a nuclear power plant (and presumeably one with an eye towards weaponization) can't bypass or falsify. This device just changes the avenue of attack, it doesn't solve the problem completely.

Re:Detecting (anti)neutrinos?

[syrinx]

They probably just reversed the polarity of the deflector dish; from the various documentaries I've seen on the subject that usually allows antineutrinos to be detected.

Re:Detecting (anti)neutrinos?

[Anonymous Coward]

First, it's very very heavy. You need a thick lead shield to block cosmic rays, but that's not the biggest problem.

Neutrino (antineutrinos work the same, but give off a different signal) collisions are very rare. The device needs to be close to the source, so that many neutrinos pass through the device. The density of neutrinos fall off as the square of the range (inverse square law). If you double the range, you get one quarter the number of collisions. Even close to the reactor, they are rare enough that it's hard to tell collisions from the local reactor versus background noise (the sun and other reactors are probably the biggest sources). This why it takes them hours to figure out when the reactor has turned off. The whole thing relies on the statistics of a very low probability event. From space, the background noise would easily swamp the signal from a specific reactor.

You might be able to tell which part of the earth is releasing more neutrinos if your orbit was low enough, but it would be very tough to pinpoint a source to a specific country. It would be very hard to get both decent spacial resolution and time resolution.

Unlike this detector, then neutrino detector at South Pole, Amanda, can tell which direction a neutrino came from. It uses the Earth for shielding and many kilometers of ice as the collision target. I assume they detect neutrinos from reactors, but probably not often enough to tell exactly when they are on (just a guess).

Re:Detecting (anti)neutrinos?

[Anonymous Coward]

Yeah, and then you just need a secure channel for that data to travel on. What were you thinking of for that? Hooking it into an internet connection?

Yeah, pretty much. Or a satellite phone or whatever.

Secure communications without a secure channel to exchange information beforehand are hard, as is keeping those communications secret. Neither of those things are a problem for a detector installed on site with the knowledge of everyone involved. It can just phone home periodically with a one-time-pad.

Re:Detecting (anti)neutrinos?

[Carnildo]

The problem is one of mass, not of interference. It takes a long time (days) to start a reactor back up after shutting it down, so a satellite in a typical 90-minute polar orbit could check every reactor on Earth twice a day, at a distance close enough to tell it from all other reactors. Since the atmosphere provides almost no shielding against high-energy cosmic rays, both a ground-based detector and an orbital detector require some other way of filtering those out.

However, such a satellite would be too massive to launch. A detector with a 50-meter range weighs about 1000kg, and neutrinos obey the inverse-square law. A satellite at an altitude of 500km would weigh over 1,000,000,000 kg.

Re:Detecting (anti)neutrinos?

[Anonymous Coward]

The earlier version of this reactor (Kamioka) was also a very big reactor, which detected about one solar neutrino a day.

Of course, they were very interested in directional information, and relied on neutrino-electron elastic scattering, so there may be reactions with higher detection rates.

Re:Detecting (anti)neutrinos?

[ZackZero]

Disclaimer: I am NOT a particle physicist (but I did stay at a Holiday Inn Express last night). We seem to be drawing an overall conclusion that it is antineutrinos that are being sought by these detectors. However, since the neutrino and antineutrino are both neutral (read: they have no charge) particles, is it not possible that they are the same particle, or perhaps simply two variants of a core type of particle?

If I recall correctly, the only differing property between the neutrino and antineutrino is helicity; the neutrino has left-handed helicity, the antineutrino right-handed. Perhaps someone can clarify this a bit better?

Re:Detecting (anti)neutrinos?

[Tenebrousedge]

So you, a rogue nation, have physical access to an irritating monitoring device. You don't even have to get inside the box to screw with its results---you can wall it off with lead, or point a beam of neutrinos at it. You can open the box, and hack the device within. You can prevent it from dialing home, and play games with any subsequent inspectors. One time pads aren't a magic bullet, either. You have to keep a copy of the pads on the machine in question, and they have to be kept secret from the person who happens to have physical control over the device. Not possible.

Re:Detecting (anti)neutrinos?

[Anonymous Coward]

Would this prevent the use of such detectors in satellites? I realize that this first design requires that it be essentially next to the reactor, and that its time resolution is far too short for common orbits. But would there be too much interference in space for this to ever be of practical use?

According to the article, the device has filter materials meant to reject cosmic rays before they reach the detector. They're also looking for a very characteristic double-detection event; the anti-neutrino reacts with protons in the tank in a two-stage reaction that produces two gamma rays seperated by a very small amount of time. (The gamma rays are then converted to visible light through the use of a scintillating material, and detected with photomultiplier tubes)

By all sounds, they've done a very good job both in hardware and software to eliminate false detection events. Of course, take that with a grain of salt; the person who most has a vested interest in the device eliminating false detection events is also the only person telling you how good that is. If it proves out in peer-review, it'll be an impressive accomplishment...

So it might work in space. One of the size from the article would be next to worthless - it'd be good enough to tell you if a nuclear powered spacecraft was moments away from capturing or destroying your satellite, and that'd be about it... The Japanese built a 1000-ton detector that got events from most of their island nation a few years ago... maybe with these guys' techniques, you could scale that guy down to about 100-tons... but then, that's just the weight of the scintillator - the Japanese detector's scintillator was in the middle of a much larger facility...

http://en.wikipedia.org/wiki/Kamioka_Liquid_Scintillator_Antineutrino_Detector

Using that detector's sensitivity as a guideline, it has a published mean distance to the reactors it was monitoring of 180km - just barely enough for an LEO satellite to graze the surface.

Really, putting one of these in space makes no sense until more than one nation has nuclear-powered space ships up there...

There are a ton of fission-powered man made objects up there, sure... but they all use a miniscule amount of material in a low power output configuration that is likely undetectable from any distance... right now there's just nothing to detect up there...

Re:Detecting (anti)neutrinos?

[Martin Blank]

Interference wasn't the right word. One of the ACs responding to my post got what I was trying to say, mentioning the background noise.

The same AC mentioned the neutrino detector at the South Pole and its directionality capabilities. That makes for something closer to what I was imagining, something that would allow detection of unpublicized nuclear reactors. I can imagine, though, that this might get annoying for the major submarine powers if the resolution were reasonably high, as their nuclear fleet might become trackable.

It's sci-fi right now, but perhaps a captured comet in orbit around the Earth might be able to provide a similar environment to the Amanda facility. Maybe in a couple hundred years...

Thanks for the explanation.

Re:Detecting (anti)neutrinos?

[varcher75]

People usually focus on charge reversal for particle-anti particle opposition; charge reversal is a consequence of anti-particle formation, not a cause. If a given particle has, say, 3 specific quarks, its anti-particle is the one with the 3 anti-quarks of them. If the sum of the quarks yield a charge, then by nature, the anti-particle will have the opposite charge, but if the total charge is 0, then the anti-particle is also neutral - but not equivalent.

Re:Detecting (anti)neutrinos?

[NateTech]

More importantly we're assuming anyone who knew their reactor was being monitored, wouldn't be able to come up with a way to generate neutrinos and fool the detector?

Re:Detecting (anti)neutrinos?

[Anonymous Coward]

It's also interference. If the detector gives you no directionality, then when your distance to the reactor is such that the W/m^2 it would send you (if there was no shielding) is significantly less than the 1360 W/m^2 the Sun sends you, then the reactor's (anti-)neutrinos are drowned in the solar ones. (It would be better to compare neutrino fluxes directly, but W/m^2 is easily obtained from the published power output of the reactor and your distance to it.)

Re:Detecting (anti)neutrinos?

[Naturalis Philosopho]

Ummm, if you can detect that the host nation has tampered with the device, doesn't that tell you something important too? Heck, most "controls" being used on reactors right now are like fancy lock-out-tag-out bands; they don't prevent tampering, they just expose that it happened. It's the people who visit the sites (or who aren't allowed into the sites, which, again, tells you something) which do the actual detecting. This anti-neutrino detector is just another tool, not a panacea.

Tampering

[pryoplasm]

If a group of people are willing to shut down a nuclear power plant in order to get materials for weapons, what is to prevent them from tampering with this detector? As far as safeguarding that the material does not fall into the wrong hands, the fact that it could happen makes the detector a moot point.

And besides, if we know when plutonium is stolen, we'll never get that DeLorean over 88mph again.....

Great Scott!

Re:Tampering

[clonan]

perhaps the fact that the tampering would be discovered the next time someone came to collect the data...

Re:Tampering

[edward2020]

what is to prevent them from tampering with this detector?
I imagine that the device would have some kind of anti-tamper system that would alert the IAEA that someone was mucking with the machine - just as it would alert them to the presence of

As far as safeguarding that the material does not fall into the wrong hands, the fact that it could happen makes the detector a moot point.
An analogy of this statement would be "As far as safeguarding that people do not kill other people, the fact that it could happen makes trying to prevent murder a useless exercise.

Re:Tampering

[amplt1337]

Ugh, you're one of those jerks that messes with the smoke detectors in airplane lavatories, aren't you?

Seriously, though, you're absolutely right; leaving a known automatic monitoring device around is just asking for somebody to figure out a way to spoof it or turn it off without being detected. Countries that are willing to sell off their reactor fuel must need money even more than they need energy*, and that's precisely the spur to push some good old-fashioned brainpower into action.

*or have their reactors overseen by greedy functionaries who want money more than they want a reputation for success and political advancement; same effect.

Re:Tampering

[Waffle Iron]

If a group of people are willing to shut down a nuclear power plant in order to get materials for weapons, what is to prevent them from tampering with this detector?

After they open the detector, they wont know if they're supposed to cut the red wire or cut the blue wire.

Re:Tampering

[MoFoQ]

dunno how knowing when plutonium is stolen translates to the delorean never going over 88mph....'cuz shoot...thought "where we're going, we need no roads"

man...if only we had "Mr. Fusion"...then we don't need to worry about neutrino detectors (unless those underpants gnomes find a way to use it to their advantage...then we need to worry).
just pop in a six pack into it and call it good.

Re:Tampering

[Tenebrousedge]

The goal is to stop people with the resources to operate a nuclear reactor and presumably a nuclear weapons program from firing up a reactor without you knowing about it. With a machine that a would-be nuclear power would have physical access to in some way or another. You have successfully moved the avenue of attack. That's not to say that it's entirely worthless, but the problem still exists.

Re:Tampering

[edward2020]

It doesn't sound as though the goal is to stop the operation of nuclear reactors. The goal, in my understanding, is to detect when said reactors are turned off - which apparently indicates that fissile material may be being removed from the reactor to sell to others for, or use themselves, weapons grade material.

Please note that I'm not suggesting this device is some sort of panacea for nuclear proliferation. Merely that it could be a tool in the arsenal to prevent that proliferation. However, the mere fact that it is not a "cure-all" does not detract from its usefulness. Certainly their are problems with it - primarily, as you say, because the targeted nation has physical access to it.

Re:Tampering

[Tenebrousedge]

which apparently indicates that fissile material may be being removed from the reactor to sell to others for, or use themselves, weapons grade material.

Or perhaps when they're replacing spent fuel rods? What happens when you surround this box with a bunch of lead, or point a stream of neutrinos at it? You're right that it's a tool. The question is whether it's a good or useful tool. From what I can tell, having a much more sensitive device located much further away would be a better solution. Building those light water reactors that we promised the Koreans would probably be the best option. Oh, that's right, there's that other nuclear threat in the mideast. Well, probably having the CIA take over the country wasn't the best idea. Maybe we can learn to play nicer with the other children? Foreign policy is really over my head, I guess...

Re:Tampering

[edward2020]

Or perhaps when they're replacing spent fuel rods?

I'm sure that if this device is ever used that that could be taken into consideration. Don't fuel rods last for a predetermined, known time? Also, beyond any technical ability of this device, it may give the IAEA a reason to be sending their own people to the site of the reactor.

As to Mosaddeq - that really doesn't have anything to do with the utility of this device. It does however, help to explain why the Shah needed SAVAK to stay in power and how that certainly pissed off Iranians enough to start the Islamic Revolution of 79. And SAVAK, of course, is one reason why they hate us.

Concerning the light-water reactors, I really fail to see how us being slow in building shit for Kim Jong-Il makes us such a bad guy that we should overlook his uranium enrichment program. He blatantly broke the 94 Agreed Framework. So what, eight years was too long for him to get free energy (and 8 years is being nice, he undoubtedly had the program running before '02)? Remember, only Kim Jong-Il wants Kim Jong-Il to have more nuclear weapons. Conduct a poll of S. Korea, China, Japan, and other countries of the region and I'd bet they'd all tell you that that would destabilize the area even more. And create an even greater security dilemma.

Re:Tampering

[dunkelfalke]

if a group of people wants plutonium so badly they just build a reactor which can be refuelled without shutting down (like CANDU).

Re:Tampering

[Tenebrousedge]

Or perhaps when they're replacing spent fuel rods? I'm sure that if this device is ever used that that could be taken into consideration.

Yes, that's correct, as far as I know. It's just that this device doesn't really gather that much data, and it's probably not worth it---except, as you say, to give an excuse for inspectors to be there. A non-functioning version of the same would do just as well :) Just write "neutrino detector" on the side of the box, no one will know the difference.

Really, we've been able to detect reactors being fired up before--I seem to remember a story about satellite detection of that, or perhaps it was reprocessing, perhaps a year ago, in N. Korea. Or they claimed they had fired up a reactor, and it was disproved. Can't find a reference for some reason. Still, there should be other options.

The point is more that we the U.S. have had a hand in creating these monsters. War is hell, but it sure sells well. Missiles, tanks, fighter jets, and now---neutrino detectors? It's hard to tell where foreign policy ends and the military-industrial complex begins. If there's a distinction.

Sensitivity?

[Cyberax]

During the http://en.wikipedia.org/wiki/Neutrino_experiment they got only 3 neutrons per hour from a reactor just 11 meters from a detector.

Neutron flux obeys the inverse square law, so this detector should detect only few neutrons per _day_ at the distance if 100 meters.

It seems that this device will have a lot of false positives and negatives.

Re:Sensitivity?

[Smidge204]

You're citing an experiment performed in the 1950's.

They can make machines that are MUCH more sensitive now, and if you're only interested in detecting presence and not actual study, they don't need to be that fancy.
=Smidge=

Re:Sensitivity?

[Anonymous Coward]

Neutrons or neutrinos? I'll give ya the benefit of doubt and assume you meant neutrinos.

Re:Sensitivity?

[mapkinase]

If they can go so close to the reactor, I hope that before using their neutrino-catching gizmo to detect if reactor is off or on they will check if the ON button is actually ON. /off

sorry could not resist

Re:Sensitivity?

[Cyberax]

I'm curious how they achieved it.

Neutrino sensitivity is limited by its VERY small cross-section - it's not hard to detect gamma rays from neutrino-proton interaction.

Re:Sensitivity?

[Anonymous Coward]

During the http://en.wikipedia.org/wiki/Neutrino_experiment they got only 3 neutrons per hour from a reactor just 11 meters from a detector.

Neutron flux obeys the inverse square law, so this detector should detect only few neutrons per _day_ at the distance if 100 meters.

If you read the article, it mentions that they can monitor the on/off status of the reactor with a time resolution of 5 hours, and power output over month long intervals... if they were getting, say, 10 anti-neutrinos an hour those time resolutions would be much more granular... I would guess they're getting 3-8 detections a day based on those figures - which would fit nicely with your estimate.

They do mention that they're using some sophisticated filtering techniques (sounds like a combination of hardware and software) to try to up the detection rate and reject the falses...

good test?

[Bananatree3]

I do not know if it is also true for anti neutrinos, but regular neutrinos pass through almost every kind of matter I can think of. Since neutrinos emitted from the sun pass right through the earth, This property would make it exceptionally difficult for a rogue nuclear reactor to block anti neutrinos from being detected(as far as my limited physics understanding goes).

The underground detectors that pick up the sun's neutrinos only do so quite rarely. Maybe since this detector would be sitting right next to the source it would pick up more of them?

Re:good test?

[el_munkie]

Well, think about this, during every fission in a nuclear reactor, about 5% of the energy released goes into neutrinos. And if you were wondering, antineutrinos (as far as we're concerned here) behave the same way as normal neutrinos.

Bigotry!

[Anonymous Coward]

An antineutrino device? That's discriminatory against neutrinos.

What's wrong with infrared?

[Locklin]

Wouldn't the a simple heat-sensing camera on a satellite or other distant object be able to detect when a reactor is shut down? It's probably pretty difficult to fake all that heat output.

Re:What's wrong with infrared?

[Anonymous Coward]

Or how about recording when the reactor is turned off and on?

Re:What's wrong with infrared?

[everphilski]

You probably can't get one satellite in GEO to get a clean look at most of the interesting countries, therefore you'd need an array of satellites. Even a single satellite in GEO is probably more expensive. Even at that, cloud cover and rain will attenuate IR to some extent.

We could fly, say, UAV's over Tehran, but I doubt Iran would be a fan of that :)

I think the real key to this technology is, how far away can they measure? If the capacity can extend a few hundred miles in the future then it's possible to park this in a friendly country to monitor a hostile one.

Re:What's wrong with infrared?

[Anonymous Coward]

I think the real key to this technology is, how far away can they measure? If the capacity can extend a few hundred miles in the future then it's possible to park this in a friendly country to monitor a hostile one.

Japan has operated a 1000-ton detector at a mean average distance of 180km from their nuclear reactors nation-wide, and has been detecting events from them for years. In fact, they measured the difference between the expected number and actual number of detected events to a) prove that neutrinos oscillate to flavors that are undetectable by our detectors and b) compute the rate of said oscillation with an accuracy of 99.9998%

That was with two runs - one ~250 days, the second ~500 days

This device would not have the accuracy to monitor shutdowns over that distance (you need to detect a few antineutrinos a day from each reactor to do that) - but it also wasn't built with this team's apparently unique and novel methods of detection and filtering...

BTW, the article states the exact opposite viewpoint - the inventor believes the key to this devices adoption is that it is simple and cheap to manufacture - but they're looking specifically for implementation by the signers of the nuclear anti-proliferation treaty; who have already agreed to international oversight of their reactors...

Re:What's wrong with infrared?

[dunkelfalke]

a scrammed reactor still produces decay heat for quite a while, even spent fuel does it.

Re:What's wrong with infrared?

[Guppy06]

"It's probably pretty difficult to fake all that heat output."

And how much oil is Iran sitting on top of again?

If I read this right...

[Thelasko]

Then this machine can only detect whether the reactor is operating above 80% power or above. So, if you operate at 50% power it cannot tell if the reactor is off or not.

Re:If I read this right...

[Carnildo]

Then this machine can only detect whether the reactor is operating above 80% power or above. So, if you operate at 50% power it cannot tell if the reactor is off or not.

One of the things that makes reactor operation so hard is that they don't like being run at low power. If you run a reactor at 50% power for more than a few minutes, the buildup of fission byproducts will cause the reactor to shut down, requiring a very expensive restart process.

Re:If I read this right...

[BlueParrot]

That isn't a problem because the difficulty is to detect when the reactor is off thou they claim it isn't. During normal operations a reactor will run close to full power for up to a year at a time, but if you want to produce nuclear weapons you must keep shutting it down to refuel since leaving the plutonium in the reactor for too long severely degrades its suitability in a bomb. Thus all the detector needs to do in order to blow the whistle is to show that the reactor operated in a very unusual pattern rather than the continuous high power mode that is more common.

Furthermore, for baseload plants like large nuclear power stations you can't just change the power output as you like because the type of turbines used do not spin up and down very easily. Special load-leveling plants ( typically natural gas or hydroelectric ) are used for this purpose, so if somebody is running a large baseload nuclear plant at 50% power it would almost certainly attract suspicion.

Re:If I read this right...

[Thelasko]

Furthermore, for baseload plants like large nuclear power stations you can't just change the power output as you like because the type of turbines used do not spin up and down very easily. I don't think they use just one turbine for the whole plant. They could run the reactor at 50% and just use, for example, two out of three turbines.

Special load-leveling plants ( typically natural gas or hydroelectric ) are used for this purpose, so if somebody is running a large baseload nuclear plant at 50% power it would almost certainly attract suspicion. But my point is, it won't raise suspicion that they are running the plant at 50% power because the detector couldn't tell if it was.
The rest of your response sounds valid. I don't know the details of producing plutonium. However, I don't think the detector would know the difference between turning the plant on and off several times in one month and running it at 50%. It uses some pretty thin statistics to make it's decision.

Re:If I read this right...

[dunkelfalke]

doesn't that depend on the reactor type?
the chernobyl RBMK was operated at 20% power without shutting down and had a runaway reaction after a scram because of bad control rod design.
marine propulsion reactors afair also can change their output power fast.

Re:If I read this right...

[Wonko the Sane]

doesn't that depend on the reactor type?

Yes. The GP was speaking from an opening not normally used for communication.

In a U-235 reactor, the fission of uranium produces iodine, which decays into xenon, which is a poison. The rate of iodine production is proportional to the fission rate.

If you operate at a high power for an extended time, you will build up a large concentration of iodine. If you then change to a low power, xenon will spike because all the iodine is still there decaying, but the neutron flux is not removing the xenon as quickly.

If the reactor does not have enough excess reactivity in the form of control rod withdrawal, then it can shut down the reactor until the xenon has decayed.

But if you operate continuously at a low power then iodine will be at a lower concentration. You only see a xenon spike when you suddenly drop power from high to low.

Re:If I read this right...

[Detritus]

You can design the reactor to allow refueling during operation.

Re:If I read this right...

[b0s0z0ku]

In a U-235 reactor, the fission of uranium produces iodine, which decays into xenon, which is a poison

By "poison", it's meant that it absorbs neutrons and discourages fission, not that it's toxic to life.

-b.

It would be nice if nuclear powers let the IAEA in

[Anonymous Coward]

The policies of the present Israeli Government have obstructed the peace process in the Middle East and all initiatives to free the region of the Middle East of weapons of mass destruction, and in particular of nuclear weapons, have failed.

No less than 4 UN general resolutions and 5 IAEA resolutions. Is there a problem here?

damn right i'm posting anonymously.

Reverse the Polarity of the Neutron Flow!

[jameskojiro]

Activate the anti-neutrino positron beam and route auxillary power to the secondary deflector dish!!!

We must defeat the Cyborg Overloards!

It's *that* hard to detect whether a nuclear...

[exp(pi*sqrt(163))]

...reactor has been running? Surely you just look for people running round glowing green or with extra limbs. And if that's not the case, it seems like the environmental impact of nuclear reactors is less than some people would claim.

Re:It's *that* hard to detect whether a nuclear...

[AJWM]

if that's not the case, it seems like the environmental impact of nuclear reactors is less than some people would claim.

Bingo!

Re:It's *that* hard to detect whether a nuclear...

[Anonymous Coward]

Even though it's sort of a not-so-well thought-out question, I'll bite.

When sometimes the discussion goes to pollution of nucear power plants, the discussion is not that it pollutes on a daily basis it's immediate surroundings. Indeed, if all things go well it should be a remarkably clean operation.

However:
- there is the small question of what to do with the fuel rods, some other consumables, and even the power plant itself, after they are "spent"
- in case of an incident, pollution does become relevant (this does not have to be a big bang, but can be leaks into the ground)
- the production of the fuel rods is by the way also a pretty dirty job

It is also important to note the fact that incidents very hard to clean up. So in a theoretical function of "toxicity", "chance it might happen" and "cost to clean up" we have -to offset the others- done a heck of a lot to reduce one of those coefficients, but *if* it happens it is really bad news.

Re:It's *that* hard to detect whether a nuclear...

[nuzak]

Sure, but they can always bus in mutants for the days they shut down the reactor.

Sheesh.

Re:It's *that* hard to detect whether a nuclear...

[dunkelfalke]

build better reactors. spent fuel is still fine for some of the reactor types, some really bad elements can stay in the reactor or be transmutated and the waste of those reactors should be safe after a much shorter amount of time.

Antineutrino Device?

[Yvan256]

Is that an idea for a script for a ST:Voyager episode?

Re:Antineutrino Device?

[Anonymous Coward]

I can't remember the names, but there've been one or two sci-fi stories where (in one case) all nuclear weapons on earth were neutralized, and other I think everything was made non-radioactive, so no nuclear reactors or bombs. (Not mentioned are the smoke detectors and other stuff this would also bring to a dead stop.)

          Now THOSE are some antineutrino devices 8-).

Neutron Jammer

[BobSixtyFour]

Oh please, those ZAFT coordinators shouldn't try to hide the REAL name of the device: The Neutron Jammer. Hopefully we on earth will develop the Neutron Jammer Canceller before the the Bloody Valentine Tragedy. "For a blue and pure world!"

Antineutrinos to stop proliferation

[Anonymous Coward]

Now, if we could fire antineutrinos at any illegal reactors and destructively interfere with them...

CANDU/RBMK and continuous refuelling

[b0s0z0ku]

Some reactor designs, like CANDU and RBMK have separate water channels for each fuel rod, so they can be refuelled whilst in operation. So this device will only affect a limited subset of reactors. Same thing with the new pebble-bed reactors -- the fuel "pebbles" are continuously recycled -- being removed out the bottom and readded. -b.

Nuclear "club" and poorer countries

[b0s0z0ku]

BTW, what exactly gives the members of the nuclear "club" -- US, Russia, China, UK, France, India, Pakistan (Israel/Japan) and their friends the right to reprocess their fuel and have a viable nuclear industry, while growing economies are not given that right? Reprocessing fuel does NOT have to be for the purpose of producing nuclear weapons -- if the fuel is reprocessed, they don't have to buy as much new fuel from other countries, and the quantity of waste also goes down. This is a ploy by certain countries to control the energy industries of developing economies, in addition to a way to stop the spread of nuclear weapons. PS- guess which county was the ONLY one to use nuclear weapons in anger so far? -b.

Re:Nuclear "club" and poorer countries

[Anonymous Coward]

What gives army scientists the right to play around with sarin gas, C4 and ricin, and not me, a private individual?

It's not a joke question. I suspect the answer is either "might makes right" or a thousand pages long.

Re:Nuclear "club" and poorer countries

[Free the Cowards]

Is this a serious question? What gives them the right is that they were there first, they have lots of nuclear weapons and powerful conventional armies.

This may not be the most moral stance, but morality has never had any particular link to international relations.

Re:Nuclear "club" and poorer countries

[b0s0z0ku]

Is this a serious question? What gives them the right is that they were there first, they have lots of nuclear weapons and powerful conventional armies.

In which case, one can only HOPE and pray for more proliferation. So that the poorer countries can defend themselves against bullying from the established nuclear powers.

-b.