Toshiba Pushes Safe, Small Nuclear Reactor Design 965
core plexus writes "This article describes a proposal from a Japanese corporation that wants to thrust the Interior Alaska community of Galena into international limelight by donating a new, unconventional electricity-generating plant that would light and heat the Yukon River village pollution-free for 30 years. There's a catch, of course. It's a nuclear reactor. Not a huge, Three Mile Island-type power plant but a new generation of small nuclear reactor about the size of a big spruce tree. Designers say the technology is safe, simple and cheap enough to replace diesel-fired generators as the primary energy source for villages across rural Alaska."
Already been done (Score:4, Informative)
SL-1 Reactor, Idaho Falls (Score:1, Informative)
The SL-1 was a 200 kW nuclear reactor designed for electric power production for remote Artic stations. It was being operated by three men on the night of January 3, 1961. It had a two-month history of sticking control rods and the reactor had been shut down for maintenance. The crew was to assemble the control rod devices and prepare for startup.
Radiation alarms sounded, monitors a mile away gave alarms and health physics people rushed to the reactor. The building was intact and the lights were on, but they measured a level of 25 rads/hr at the entrance and 200 rads/hr as they approached the control room.
On a rush to the reactor, they found it a shambles and found radiation levels over 500 rads/hr. With protective suits, they rushed to the reactor building and found two of the men, one still alive. They found the third man impaled by a control rod, pinned to the ceiling.
Once the bodies were removed, they measured over 400 rad/hr from the bodies, too hot for a normal burial.
This was a non-pressurized system. No meltdown occurred and less than 10% of the radiation was released, but it represented the worst nightmares about nuclear accidents.
I 0wn j00 (Score:1, Informative)
TOSHIBA makes new NUCULAR reakt0rs.
nucular reakt0rs bl0w up at pred3t3rmined time.
t0$h1ba 0wns us.
Skynet virus mak3s its3lf kn0wn @ t0sh1ba
too late.. Skynet nukes t0$h1b4 wh3n th3y try to k1ll virus.
Governor Arnie in new movie.
+5 Lame
Reactors evolution (Score:5, Informative)
-Big hunk of uranium in a pool of water*. Water heats but is under pressure so it can't boil. The water (contaminated and radioactive) is then piped through fresh water (in sealed pipes) from a lake or river transferring heat so the fresh water will boil and turn turbines. Neutron absorbing control rods are raised or lowered into the big hunk of uranium to control the reaction. Problems can occour with pipes corroding and releasing contaminated water*, control rods can jam, leaks in the coolant water* can cause a loss of coolant leading to an overheated reactor.
-Little pellets of uranium in a pool of water*. Same principle as above, only there are no control rods. As the pellets heat up, the expand, increasing the distance between the pelets. This is much safer because there are no control rods to jam. Loss of coolant can still be a problem, but easily solved by simply moving the pellets further apart.
-And now, this reactor.. a Big Rod of Uranium is immersed in a pool of water*. The rod of uranium is sub-critical so it can't sustain a (large) heat producing reaction on its own. A sleve made of neutron reflecting material (google for nuclear bomb neutron reflector) slowly makes its way along the BRoU over the reactors 30-year lifespan. Only the uranium surrounded by the sleve can react. If the sleve moves too fast, then the reactors lifespan is simply shorted - it will never produce more heat than can be made via the reflector. If it moves too slow, the reactor simply produces less heat. Overall a very good design. If I were to have a reactor in my backyard, I definately would choose this style.
I've gotta hand it to the toshiba people.. I wouldn't have thought of this... pretty cool.
*Note: Water may not be water. Water is often used because of its high specific heat, but many other liquids have been used as coolant. In the toshiba reactor, liquid sodium is spec'd because its non-corrosive. A big plus in a maintenance-free environment.
Re:Well, this is a good place to start (Score:4, Informative)
Re:nuclear power is cleaner.... (Score:4, Informative)
It's been thought of. Google for "nuclear waste subduction". The problem is that subduction is a long, slow process, punctuated by violent activities like earthquakes and volcanoes.
You could accumulate a lot of waste in a given area that was slowly being pulled under, and then an volcano blows it all back up again. Or an earthquake cracks the seals and you've got contaminated groundwater or whatever.
The problems seem solvable with careful choice of site(s). There are places where the odds of such things are quite small. Pick someplace offshore, for one thing.
In reality, you'd have a greater risk of an accident in transporting the waste there than in any major incident happening.
why we fear nuclear power (Score:4, Informative)
Re:nuclear power is cleaner.... (Score:1, Informative)
Even if it's not napalm-b, regular napalm is just jellied gasoline. It's less volatile and less dangerous than the stuff you put in your car.
Re:nuclear power is cleaner.... (Score:5, Informative)
Re:Ignorance (Score:1, Informative)
-- Seth Woolley
Secretary and Coordinating Committee Member, Pacific Green Party of Oregon
not really (Score:3, Informative)
Back feeding lines is an issue, but not as big as you might think. In nearly all cases your house is not the only one isolated, thus when you start backfeeding lines, all your neighbors think they have full grid power and start to use it, but since you don't have an unlimited supply of power, the breakers (and fuses) on your generators trip. Thus you are forced to correct the problem before you can use your own backup. That said, back feeding does happen, and it is dangerious. Dangerious enough that line workers short known dead lines before touching them so they are not a good path.
Second, in many states (Minnesota where I live for sure) the power utility must hook up any residentialy co-generation plant and use all power supplied. The amount they pay you is regulated somehow, but I'm not sure of the details. (You won't make enough to pay for a gasoline generator, but for wind, hydro or solar uses it can break even)
Re:nuclear power is cleaner.... (Score:2, Informative)
Re:Pollution Free? (Score:2, Informative)
Re:nuclear power is cleaner.... (Score:2, Informative)
Plutonium is not as chemically toxic as some think. I know many people carrying multiple body burdens. See http://www.aps.org/apsnews/articles/11351.html for more info on others with high body burdens. Again, I would suck down a bottle of pu spiked water but it is not an immediate death sentence like taking cyanide.
I agree that much more radiation is released from coal fired plants than nuclear. It has been shown in McBride, J.P., R. E. Moore, J. P. Witherspoon, and R. E. Blanco, Science 202, 1045 (1978) that you receive a higher radiation dose by living next to a coal-fired plant that you do living next to a nuclear reactor.
Re:SL-1 Reactor, Idaho Falls (Score:4, Informative)
Re:Well, this is a good place to start (Score:3, Informative)
Nope. The Chernobyl reactor caught fire. It used a graphite moderator (a design not used in the US) which caught fire when the coolant water boiled down low enough to expose it to air. The Chernobyl design was basically an accident waiting to happen -- it was actually worse than a meltdown. (In a meltdown you're left with a pool of radioactive metal that's no longer critical all over the floor of the containment building.)
Re:Well, this is a good place to start (Score:4, Informative)
Re:Villages? (Score:1, Informative)
It seems like a very safe fail-safe measure. Practically infallible.
Pebble Bed & 3 Mile Mythology (Score:3, Informative)
http://web.mit.edu/pebble-bed/ [mit.edu]
Also, whenever people invoke Three MIle Island, I'm always obliged to point out that ZERO nuclear waste was released during the accident. It was all completely contained. Most people think it was like Chernobyl, but the fact is: the safety standards worked for 3-mile.
Quick primer on nuclear physics (Score:3, Informative)
For each element, there is a small list of stable isotopes. If a nucleus becomes unstable for whatever reason, it attempts to return to a stable configuration. There are several ways this can happen, including radioactive decay and fission.
The nucleus of any atom is held together by binding energy, and tries to fly apart due to electric repulsion between the protons. The binding energy per nucleon has a broad maximum around 8 MeV and nuclear mass between 50 - 75. Unstable, heavier nuclei may undergo fission into smaller nuclei with higher binding energy. The difference is released as heat, which we use to generate power.
The electric repulsion increases as the square of the number of protons in a nucleus, so more neutrons per proton are needed for heavier elements to maintain stability; however, there is a limit, and elements beyond Bismuth (83) are naturally unstable. These nuclei undergo radioactive decay, which occurs in two types: alpha and beta.
Unstable, heavy nuclei emit alpha particles, which are identical to Helium nuclei -- two protons, two neutrons. This radiation reduces the atomic mass by roughly four, eventually bringing the element to a stable nucleon count. Unstable nuclei also can undergo beta decay, converting a neutron into a proton and a high-energy electron, which is emitted. The amount of time needed for half of a sample of material to radioactively decay is called the half-life.
For fission, there are only three isotopes with a long-enough radioactive half-life to be stored and transported, and which are fissionable by neutrons of all energies: Uranium-233, Uranium-235, and Plutonium-239. U-233 isn't natural, and is created by inducing Thorium-232 to undergo beta decay by adding a neutron. U-235 occurs in small but extractable quantities in natural Uranium ore. Pu-239 is created by U-238 neutron capture and beta decay.
Alpha- and beta decay cause ionization in matter with which they come in contact by knocking off outer-shell electrons. Alpha radiation for Pu-239, the most energetic alpha decayer in a reactor at 5.1 MeV, has a range of only 3.6 cm in air, after which it is low-enough energy to absorb two electrons from the air and become a Helium atom which can't ionize. Uranium reactors, like the Toshiba model, have even smaller alpha ranges. Nuclear reactors are not at risk for leaking alpha radiation.
Beta radiation consists of electrons, which are much more likely to scatter when they ionize, so there isn't a specific ionization range for beta radiation. On the other hand, the highest energy beta radiation from fission reactions is on the order of 3 MeV, and can be stopped by half a centimeter of concrete. There is no possibility of beta radiation escaping nuclear reactors.
Gamma radiation, produced by neutron capture reactions, drops off exponentially as it is absorbed, so it can be reduced to background levels by a manageable thickness of iron or lead shielding. Normally, this occurs immediately surrounding the reactor vessel itself. If the vessel develops a leak or the shielding fails, nuclear plants have additional concrete shielding and containment procedures. In the unlikely event that everything fails, exposure to reactor gamma radiation is comparable to going to a doctor for X-rays -- not something you'd want for prolonged periods, but not going to injure you before you evacuate. In the case of the Toshiba reactor, which is 60 feet underground, there is no possibility of gamma leakage because the ground acts as shielding.
Re:SL-1 Reactor, Idaho Falls (Score:5, Informative)
http://www.radiationworks.com/sl1reactor.htm
"A small, 3MW experimental BWR called SL-1 (Stationary Low-Power Plant No. 1) in Idaho was destroyed on January 3, 1961, when a control rod was removed manually."
snip
"A careful examination of the remains of the core and the vessel concluded that the control rod was manually withdrawn by about 50cm (40cm would have been enough to make the reactor critical), largely increasing the reactivity. The resulting power surge caused the reactor power to reach 20,000MW in about
1) 3MW not 200kW - Makes a difference
2) It did "melt down" - effectivly anyway
3) It did contain water (presurized or not I dunno)
4) It was caused by human error
5) It was probably a lot larger fuel block
Silly FUD's, google will always win!
Re:Well, this is a good place to start (Score:2, Informative)
Re:Well, this is a good place to start (Score:3, Informative)
Re:Villages? (Score:5, Informative)
A million plus dollars buys a security force more than able to gaurd the perimeter around a complex not larger than a school building. Security is then essentially free for these people, and in fact they are still saving a lot of money per year in energy costs. Plus they are paying for a service in their community to people that will be living in their community. And those security people will spend money somewhere.
This solution may not be fesible when there are cheaper fuel alternatives, but out there it seems to make a lot of sense.
Who's calling who an idiot? (Score:5, Informative)
What will cause more fear is idiots like you under selling the risks.
Pot. Kettle. Black.
First, by cores, you mean control rods. But you're still somewhat off track.
Second, Chernobyl was an unstable, bad design, without a containment building. It's design, RMBK 1000, was such that if things went bad, the nuclear reaction would continue, instead of shutting down.
In addition to the uranium, a nuclear reactor needs two things- a moderator (which actually promotes the fission chain reaction) and a thermal transfer mechanism, to take heat away and make electricity with it. This is beyond the control rods, which are used to shut down the plant.
In every plant in the US, water acts as both the moderator, and the heat transfer mechanism. Lose the water, and the chain reaction is unsustainable. You can't take away heat anymore, but the fission chain reaction slows down dramatically. This is what happened at Three Mile Island (TMI)- they lost the water. They melted parts of their core, but that was the extent of the meltdown. The reactor vessel did it's job and physically contained the uranium. The containment building did it's job, along with all the auxillary systems, and no appreciable radiation was released to the public. TMI proved that we can handle a disaster without endangering the public.
Back to chernobyl. The RMBK 1000 reactor used water as a heat transfer mechanism, and graphite as a moderator. So when they lost water cooling, the reaction actually increased in power, and this raised power output lead to a rapid spike in temperature and pressure, blowing the lid off the reactor core and destroying the building.
Moreover, if they attempt to sustain low power levels (20% of capacity), the system is unstable. Because the core was huge, it was possible to have pockets of reactivity that couldn't be well controlled. When the power level is low, the cooling water/heat transport flow is reduced, to keep proper operating temperatures. But because they had pockets of reactivity that could be greater than average, there could be local areas where the flow was inadequate, boiling off the water prematurely, and getting us back the increasing reactivity with water loss that I mentioned earlier. Hence, they where supposed to operate below 20% power.
As for the people, despite earlier problems at different plants, they were not aware of the aforementioned technical problems. The Soviet bueacracy prevented any useful exchanges on such subjects. This is not to excuse them from not knowing more about their plant, just to paint a picture.
The cause of this was ironically a safety experiment. When a nuke plant is shut down, it still produces a significant amount of heat that must be removed. Normally the power required to run the pumps to remove this heat comes off the grid from other power plants, but if the plant is disconnected from the grid, a diesel generator is used instead. It took them three minutes to start the diesels (as opposed to a ten second standard in the US), so the engineers thought that they could bridge this three minute gap by extracting power from the turbine while it was in the process of coasting to a stop.
In order to test this theory, they deactivated every single safety system the plant had, and brought the power levels down to 6%. I've already talked about why this was bad.
At the end of their 'safety test', they inserted the control rods successfully, and in a hurry, because they could tell they were losing control of the plant. Because of the horrible design, though, these control rods where insufficient to kill the chain reaction, and instead only displaced water, which brought the power levels up to 100 times normal. Kaboom. The 'successful' insertion of the control rods was the final event in an idiotic string of actions.
They had no understanding of the safety i
Things people are forgetting about the whole thing (Score:4, Informative)
A) the "dirty bomb" (a current favorite among hte fear mongering media) made out of radioactive materials is generally NOTHING like the multiple-megaton weapons that make the big fancy mushroom clouda. These are bombs that expode conventionally, and through said explosion, scatter radioactive materials around an area, creating a hot zone that will possibly kill, probably sicken, some people right near the area, but mainly just go to scare the millions of people into knee-jerk reactions though non-understanding.
B) Making a cheap and nasty little dirty bomb can be easily done by stealing the Cesium 137 out of a few hospitals (canisters of it are used in x-ray machines - i think its an xray machine). The added benefit of this is that the material is a very fine powder that can get spread widely by the wind.
One of these canisters got loose in Brazil once. [pbs.org] Resulted in killing four and made a few people sick. THe cleanup was a tad nasty. People heard about it, and thousands of them showed up at hospitals to get checked out for possible contamination. This was after local officials told them "Look, you were in the immediate area, youre going to be fine." People still stood on line at hospitals, choking hospital resources and generally fucking up their ability to take care of those that were really hurt.
[If you get a chance, find that Dirty Bomb special NOVA did a while back. [pbs.org] This is the ref for that cesium info above]
Stealing a fat hunk of reactor core would involve about a million times work, and unless they wannt rub the thing against a cheese grater for a while, they're left with one solid hunk of radioactive material, which is fairly easy to handle, contain, and bury somewhere.
[again, go read that NOVA site.]
C) Your average goober (read: 98% of the population) is completely unaware of that fact that we're constantly being bombarded with "background radiation" every second of every day. They're also unaware that our skin does a pretty good job of fending that low-level shit off.
D) Imagine if mass media existed at today's level in Edison's time. Getting people to accept the fact that electricity was not going to jump out of an unused outlet (or a wire) and kill you [in everyday non-dubmass use] would be next to impossible, and
E) People Die. Its something we all do, and ya can't avoid it, so stop fucking scaring yourselves into non-action. You can only hope its not going to be horrible. Generally, not being a stupidass - and keeping yourself aware of (AWARE, not SCARED) the other stupidasses around you - will go a long way in accomplishing this.
Re:Small portable reactors are nothing new (Score:4, Informative)
Binkleyz, ET2(SS), USN, Ret.
I dont like how the press message is written (Score:3, Informative)
Because of its design and small size, the Toshiba reactor can't overheat or melt down, he said, unlike what happened in the 1986 accident at Chernobyl that killed 30 people and spewed radiation across northern Europe.
While the new type of reactor might be perfectly safe, why do they spread "disinformation" then? Of course, the "blow up" of Chernobyl only costed about 30 lives. The cleaning up recruits of the USSR army had about 1000 falacities later. Seems they don't count.
Anyway, besides the credibility of the press release the question of how to take care about burned out units remains.
angel'o'sphere
Re:Who's calling who an idiot? (Score:2, Informative)
1. The reactor was actually in a rather unknown state: while powering down for the experiment the grid operators asked for more power, so they powered it back up, and then powered it down. The accident occurred when it was relatively cold, and as I remember, they removed the control rods WAY beyond the maximum allowed to try to get it hot (evidently doing that experiment was VERY important to someone).
2. As mentioned, the RMBK 1000 design is unstable, especially at medium power. In this design, water is a neutron "poison" (as well as a heat remover). This design has a fatal flaw that Edward Teller got outlawed in the US: a "positive void coefficent". Specifically, if steam bubbles (voids) form in the cooling water, less neutrons are stopped ("poisoned"), the nuclear reaction rate increases, causing more heat, more and bigger voids
Two related questions.
1) Why were such people allowed to run the plant?
This was the Soviet Union....
2) What prevents such people from running other plants?
Nothing at all: that's what you design plants where the worst case only causes a "engineering casuality" (i.e. loss of use of an expensive plant), no human casualties.
Re:Well, this is a good place to start (Score:4, Informative)
Re:Not a bad idea (Score:1, Informative)
Permafrost is a layer of ice that is present year around at some depth under the top of the soil. It is not present everywhere in Alaska, but it is present in many of the forest and woodland areas.
So what they article is trying to say is in some of these rural areas the powerplant would have to be buried at such a depth that it would be in the permafrost.
In any case I have visited many of these villages, via kayak since most are only accessable through the waterways or via plane, and I think they would be a good locations to place some sort of low polution power source. This comes from the fact that in many of these areas there are no real environmental laws so they already have high polution.
Re:Thsi is what nevada is for... (Score:3, Informative)
In water the blue glow is caused by radioactive particles exceeding the speed of light. No, not the 3e8 m/ss speed of light in the universe. The slower speed of light in water.
The glow that one sometimes sees around radium or other elements is actually particles interacting with chemical impurities around it. You get much the same effect with a black light.
small melt-down proof rxr from the '60s (Score:2, Informative)
For the curious (Score:2, Informative)
Re:Villages? (Score:3, Informative)
viva la france (Score:2, Informative)
http://www.cogemalahague.com [cogemalahague.com]