Future of nuke power in the US

[DanG 1]

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On the other hand, in California there are 4 operating nuclear power units at the moment, all producing between than 1,050 & 1,100 MW all day, every day.

My God, that's almost 1.21 Gigawatts!

- Dan G

[billvon 2,396]

>do today's solar subsidy programs have specific criteria for the cancellation
> of the program upon achievement of a certain level of technology
>efficiency?

No, it's often simpler than that. In California, for example, the incentives in the CSI program decline until there is no money left in the program (or 9 years, whichever comes first) at which point it goes away.

[rehmwa 2]

We understand each other's positions, we just don't baseline to the same philosophy. But I do think you've thought it out very well, FWIW.

...
Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[rehmwa 2]

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> In California, for example, the incentives in the CSI program decline until there is no money left in the program (or 9 years, whichever comes first) at which point it goes away.

Cash for Clunkers

no matter what, subsidies all have the same origin - the money has to come from someone(s)

I'm not a fan of taking money from my neighbor so I can buy a luxury item at a slight discount. I'm a bigger fan that the item is priced such that we can both buy it without assistance.

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Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[hokierower 0]

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the subsidies should be ... applied to the residential side. Doing so will reduce the price of residential solar panels and make it financially feasible to install in places where it doesn't make sense to construct a solar farm..

no problem - I have some simple questions

so - which taxpayers will you steal from that don't get to afford their own solar panels, and which citizens will you 'subsidize' with that money so they can get the discount solar panels?

what's your selection criteria for the those that give up their money for food and education and housing vs those that get nifty discounts on those panels?

how is the money transferred, should the subsidized just go over to the others' houses and take their cars? or should it be something less obvious?


you might reduce the "price" of those solar panels, but you aren't reducing the COST - someone has to foot that bill too.......

I'm having money stolen from me right now to help foot the bill for the Mojave Farm and I will most likely NEVER use a single watt that it produces.

I'm having money stolen from me right now so that the building that my CM company is building meets LEED Silver.

I'm having money stolen from me right now so that the lazy ass down the street doesn't have to look for a job.

I'm having money stolen from me right now because Joe Hippie in Denver wants to put solar panels on his roof.

No one group of citizens will be singled out for subsidizing, however geographic layout will play a part in people's decision to go solar depending on the economic feasibility. Dude #1 in Arizona is much more likely to go with solar than Dude #2 in Maine because of the way the sun hits the planet.

And no, I'm not recommending you take money from food & education programs, I am recommending that we simply take the funds that are currently being given to power companies to help offset the cost & operation of large solar farms and instead give them to individuals to help offset the power requirements of the overall system.

The more individuals who try and install panels, the more incentive companies will have to make them more efficient and cost less to produce. There is very little demand because the PRODUCTION COSTS are still too high for widespread use because commercial construction is using all of the resources & production capacity.

[rehmwa 2]

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I'm not recommending you take money from food & education programs, I am recommending that we simply take the funds that are currently being given to power companies to help offset the cost & operation of large solar farms and instead give them to individuals to help offset the power requirements of the overall system.

So there is a couple things here:

1 - your list of complaints of how money is spent sounds like you're on my side in general philosophy. cool. But listing a ton of spending one disagrees with to justify something they do want is not really a serious part of any policy discussion.....

2 - "I'm not recommending you take money from food & education programs" Let's be clear - the money comes from PEOPLE, not PROGRAMS. Let's make sure it's very clear that this is not a faceless bag of cash, it's people's resources. It's human effort.

Short question - do you think it's right to take money from that guy in Maine to pay for the Arizona guy's solar panels?

(any discussion about money not being used wisely elsewhere is pretty moot - if it sucks, they shouldn't spend the money at all, not just transfer it to something that some consider subjectively - i.e., one area of irresponsible spending isn't offset by just doing it elsewhere - do you see what I mean?)

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Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[rehmwa 2]

Actually, I'm better off doing this in blue

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I'm having money stolen from me right now to help foot the bill for the Mojave Farm and I will most likely NEVER use a single watt that it produces.fight to get that fixed - has nothing to do with this topic though

I'm having money stolen from me right now so that the building that my CM company is building meets LEED Silver.fight to get that fixed - has nothing to do with this topic though


I'm having money stolen from me right now so that the lazy ass down the street doesn't have to look for a job.fight to get that fixed - has nothing to do with this topic though


I'm having money stolen from me right now because Joe Hippie in Denver wants to put solar panels on his roof.AH HA - you do understand, you really do


No one group of citizens will be singled out for subsidizing,nonsense, the guy that wants panel gets it, the guy that's waiting, chooses not to, or can't yet afford it is paying
however geographic layout will play a part in people's decision to go solar depending on the economic feasibility. Dude #1 in Arizona is much more likely to go with solar than Dude #2 in Maine because of the way the sun hits the planet. so moving money from the people of Maine to the people of Arizona, and then into the solar panel companies' banks is fair?


And no, I'm not recommending you take money from food & education programs??
, I am recommending that we simply take the funds that are currently being given to power companies to help offset the cost & operation of large solar farms and instead give them to individuals to help offset the power requirements of the overall system.or we delete that expense completely and let the people keep those dollars so they can choose to buy what they believe is best for them - irresponsible subsidy to the companies is bad one subject. cancel the program and stop taxing for it - give the money back


The more individuals who try and install panels, the more incentive companies will have to make them more efficient and cost less to produce.so will market forces IF they really are the best solution
There is very little demand because the PRODUCTION COSTS are still too high for widespread use because commercial construction is using all of the resources & production capacity
therefore, the product is not ready for prime time - YET

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Driving is a one dimensional activity - a monkey can do it - being proud of your driving abilities is like being proud of being able to put on pants

[PiLFy 0]

The US Navy proved Nuke power is perfectly safe in the Fifties. If done properly? It remains a perfectly safe, efficient power production method.

I have a question. It may have been answered in the media. I don't watch TV. The Japanese are no strangers to technology. Why in the H*** didn't they scram the reactors When the quake hit? That's the correct term, right? When they jam the cooling rods all the way in, & shut down the reactor core.

[billvon 2,396]

>Why in the H*** didn't they scram the reactors When the quake hit?
>That's the correct term, right? When they jam the cooling rods all the way
>in, & shut down the reactor core.

They did. When you shut an operating reactor down, it still generates some power from radioactive decay. If you have a 700mW reactor, for example, after shutdown it still produces about 50mW for a while. That is enough to cause core damage if cooling water is interrupted for a significant time.

[cloudseeker2001 0]

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The tsunami wiped those out.

I know a lot of other things must be going on and the "no electricity to the pumps" is what they are telling the world. But, I can make a phone call and have a portable generator on a flatbed truck in a couple of hours and I can wire it directly to the pumps myself.....I would think the nation of Japan can do the same.....

"Some call it heavenly in it's brilliance,
others mean and rueful of the western dream"

[billvon 2,396]

>But, I can make a phone call and have a portable generator on a flatbed
>truck in a couple of hours and I can wire it directly to the pumps myself...

Could you do it if the switchgear and power terminals for the pumps were under five feet of seawater?

[PiLFy 0]

It has been documented that they did this? They've got meltdowns going @three different cites.

[billvon 2,396]

>It has been documented that they did this?

Did what? Connected external generators? I know they did that in at least one case. (Fukushima I.)

[Nightingale 0]

The conclusions drawn when an electrical engineer, a civil engineer, and a mechanical engineer come together over Guinness:

Build them.
Build them in areas far away from the ocean.
Build them in areas that are not prone to quakes.
Yet build them to the best earthquake standards.
AND the best tornado standards.
Combined.
And make sure there are sufficient back-up generators to make everything running.

And since the plants require water for cooling... all nuclear power plants will now be located in: SALT LAKE CITY! There is a large lake, it's central, and well, um... (they look at their beer and refrain from political incorrectness and order another round, noting that if someone else isn't drinking it, they must make up for it!).

Yes, you will have to run power lines, but better the lines go down than the plant blow up.

Problem solved, more Guinness was ordered, and they turned to me and told me to write the law to make that happen and figure out how to put it on the ballot in every state.

um, guys? I'm a lawyer, not a miracle worker, and it'll take a LOT more Guinness to solve that one.

And I need to remember not to drink with engineers.

[PiLFy 0]

When all else fails. Read the news... You were right. They did scram the reactors when the quake hit. A nine on the richter scale is damn near biblical. I don't think this disproves nuke power is safe.

[hokierower 0]

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Actually, I'm better off doing this in blue

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*SNIP*AH HA - you do understand, you really doI understand that subsidies take money from certain individuals and move it around to where the government feels that it is needed, and in this case I do believe that a subsidy is needed, however I feel that it being to the right people.

No one group of citizens will be singled out for subsidizing,nonsense, the guy that wants panel gets it, the guy that's waiting, chooses not to, or can't yet afford it is payingpaying what? a dollar? two? how do we know that he isn't taking money from the guy getting the panels?
however geographic layout will play a part in people's decision to go solar depending on the economic feasibility. Dude #1 in Arizona is much more likely to go with solar than Dude #2 in Maine because of the way the sun hits the planet. so moving money from the people of Maine to the people of Arizona, and then into the solar panel companies' banks is fair?What about the money from Arizona that is sent to Maine for road de-icing in the winter or some other form of federal support?

And no, I'm not recommending you take money from food & education programs??
, I am recommending that we simply take the funds that are currently being given to power companies to help offset the cost & operation of large solar farms and instead give them to individuals to help offset the power requirements of the overall system.or we delete that expense completely and let the people keep those dollars so they can choose to buy what they believe is best for them - irresponsible subsidy to the companies is bad one subject. cancel the program and stop taxing for it - give the money backA person may be smart enough to make that decision, but people are stupid. They won't use it on things like this, they'll use it for some ridiculous reason and then R&D stagnates and no new developments are made. The money that a few spend to help offset their costs won't be enough. A subsidy applied correctly will help get the emerging technology onto its feet and when the subsidy is removed the groundwork will have been laid so that prices are low enough to keep new customers coming in.

The more individuals who try and install panels, the more incentive companies will have to make them more efficient and cost less to produce.so will market forces IF they really are the best solutionNo they won't. It has been proven time and time again that Americans will listen to advertising and go with a inferior product because it looks or is sold better. VHS v. Beta, Blu-ray v. HD-DVD, Plasma v. LCD, etc.

There is very little demand because the PRODUCTION COSTS are still too high for widespread use because commercial construction is using all of the resources & production capacity
therefore, the product is not ready for prime time - YETHow do we know? If the factories are re-tooled to meet the new demand of a new market, we may find that the product is ready to go, but because the manufacturer didn't find it feasible the end user got screwed over and was forced to pay for a inferior and more expensive product.

I'll keep going back and forth with you over PM but let's keep this out of this thread since we're derailing it just a bit.

[hokierower 0]

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The US Navy proved Nuke power is perfectly safe in the Fifties. If done properly? It remains a perfectly safe, efficient power production method.

I have a question. It may have been answered in the media. I don't watch TV. The Japanese are no strangers to technology. Why in the H*** didn't they scram the reactors When the quake hit? That's the correct term, right? When they jam the cooling rods all the way in, & shut down the reactor core.

Just because I turn my electric stove off after 45 minutes of cooking on high heat doesn't mean that the coils are immediately safe to touch.

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>But, I can make a phone call and have a portable generator on a flatbed
>truck in a couple of hours and I can wire it directly to the pumps myself...

Could you do it if the switchgear and power terminals for the pumps were under five feet of seawater?

And if the roads between the rental company and your house are choked with debris, cars, trees, and possibly bodies?

P.S. - I might be wrong, and that's a very real possibility because I'm not an electrical engineer, but mixing water & electricity is usually a BAD thing

[normiss 622]

And every path to get the generator to you is completely impassable for an indeterminate time.

[airdvr 197]

I've been watching CNN and they were talking about the spent fuel that is stored in the buildings. Sounds as if that is also a problem if the cooling water supply is interupted. Can anyone confirm that spent fuel remains hot?

Please don't dent the planet.

Destinations by Roxanne

[Guest]

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>Why in the H*** didn't they scram the reactors When the quake hit?
>That's the correct term, right? When they jam the cooling rods all the way
>in, & shut down the reactor core.

They did. When you shut an operating reactor down, it still generates some power from radioactive decay. If you have a 700mW reactor, for example, after shutdown it still produces about 50mW for a while. That is enough to cause core damage if cooling water is interrupted for a significant time.

Uh, not to call you out, but, a lower case "m" as you know, represents "milli-" or one-thousandth. A capital "M" represents "Mega-", or one million, and μ (Greek mu) for micro.

You know this and I am surprised you did not take the opportunity to illustrate it.



mh
.

"The mouse does not know life until it is in the mouth of the cat."

[normiss 622]

This is starting to look like a triple Chernobyl ....

This is getting scary.

[diablopilot 2]

A friend pointed me in this direction, It's a good read.




Came from this article (which is piss poor in comparison to this guy's essay):

http://www.msnbc.msn.com/id/42066534/ns/world_news-asia-pacific/?gt1=43001

Ok, the "comment" from Sam W. - 3161669:

In the aftermath of the recent earthquake and tsunami in Japan, two nuclear power stations on the east coast of Japan have been experiencing problems. They are the Fukushima Daiichi ("daiichi" means "number one") and Fukushima Daini ("number two") sites, operated by the Tokyo Electric Power Company (or TEPCO). Site one has six reactors, and site two has four. The problematic reactors are #1, #2, and #3 at site one, which are the oldest of the ten and were due to be decommissioned this year.
In short, the earthquake combined with the tsunami have impaired the cooling systems at these reactors, which has made it difficult for TEPCO to shut them down completely. Reactor #1 is now considered safe after crew flooded the reactor with sea water. Reactor #3 was starting this process as this was originally written (6:00PM CST/11:00PM GST on March 13th). Site crew began preparing to add sea water to reactor #2 around 7:30AM GMT on March 14th, if a cooling procedure does not work.
The four reactors at site two did not have their systems impaired and have shut down normally.
Can this cause a nuclear explosion?
No. It is physically impossible for a nuclear power station to explode like a nuclear weapon.
Nuclear bombs work by causing a supercritical fission reaction in a very small space in an unbelievably small amount of time. They do this by using precisely-designed explosive charges to combine two subcritical masses of nuclear material so quickly that they bypass the critical stage and go directly to supercritical, and with enough force that the resulting supercritical mass cannot melt or blow itself apart before all of the material is fissioned.
Current nuclear power plants are designed around subcritical masses of radioactive material, which are manipulated into achieving sustained fission through the use of neutron moderators. The heat from this fission is used to convert water to steam, which drives electric generator turbines. (This is a drastic simplification.) They are not capable of achieving supercritical levels; the nuclear fuel would melt before this could occur, and a supercritical reaction is required for an explosion to occur.
Making a nuclear bomb is very difficult, and it is completely impossible for a nuclear reactor to accidentally become a bomb. Secondary systems, like cooling or turbines, can explode due to pressure and stress problems, but these are not nuclear explosions.
Is this a meltdown?
Technically, yes, but not in the way that most people think.
The term "meltdown" is not used within the nuclear industry, because it is insufficiently specific. The popular image of a meltdown is when a nuclear reactor's fuel core goes out of control and melts its way out of the containment facility. This has not happened and is unlikely to happen.
What has happened in reactor #1 and #3 is a "partial fuel melt". This means that the fuel core has suffered damage from heat but is still largely intact. No fuel has escaped containment. Core #2 may have experienced heat damage as well, but the details are not known yet. It is confirmed that reactor #2's containment has not been breached.
How did this happen? Aren't there safety systems?
When the earthquakes in Japan occurred on March 11th, all ten reactor cores "scrammed", which means that their control rods were inserted automatically. This shut down the active fission process, and the cores have remained shut down since then.
The problem is that even a scrammed reactor core generates "decay heat", which requires cooling. When the tsunami arrived shortly after the earthquake, it damaged the external power generators that the sites used to power their cooling systems. This meant that while the cores were shut down, they were still boiling off the water used as coolant.
This caused two further problems. First, the steam caused pressure to build up within the containment vessel. Second, once the water level subsided, parts of the fuel rods were exposed to air, causing the heat to build up more quickly, leading to core damage from the heat.
What are they doing about it?
From the very beginning, TEPCO has had the option to flood the reactor chambers with sea water, which would end the problems immediately. Unfortunately, this also destroys the reactors permanently. Doing so would not only cost TEPCO (and Japanese taxpayers) billions of dollars, but it would make that reactor unavailable for generating electricity during a nationwide disaster. The sea water method is a "last resort" in this sense, but it has always been an option.
To avoid this, TEPCO first took steps to bring the cooling systems back online and to reduce the pressure on the inside of the containment vessel. This involved bringing in external portable generators, repairing damaged systems, and venting steam and gases from inside the containment vessel. These methods worked for reactor #2 at site one, prior to complications; reactors four through six were shut down before for inspection before the earthquake hit.
In the end, TEPCO decided to avoid further risk and flooded reactor #1 with sea water. It is now considered safely under control. Reactor #3 is currently undergoing this process, and reactor #2 may undergo it if a venting procedure fails.
The four reactors at site two did not have their external power damaged by the tsunami, and are therefore operating normally, albeit in a post-scram shutdown state. They have not required any venting, and reactor #3 is already in full cold shutdown.
Is a "China Syndrome" meltdown possible?
No, any fuel melt situation at Fukushima will be limited, because the fuel is physically incapable of having a runaway fission reaction. This is due to their light water reactor design.
In a light water reactor, water is used as both a coolant for the fuel core and as a "neutron moderator". What a neutron moderator does is very technical (you can watch a lecture which includes this information here), but in short, when the neutron moderator is removed, the fission reaction will stop.
An LWR design limits the damage caused by a meltdown, because if all of the coolant is boiled away, the fission reaction will not keep going, because the coolant is also the moderator. The core will then only generate decay heat, which while dangerous and strong enough to melt the core, is not nearly as dangerous as an active fission reaction.
The containment vessel at Fukushima should be strong enough to resist breaching even during a decay heat meltdown. The amount of energy that could be produced by decay heat is easily calculated, and it is possible to design a container that will resist it. If it is not, and the core melts its way through the bottom of the vessel, it will end up in a large concrete barrier below the reactor. It is nearly impossible that a fuel melt caused by decay heat would penetrate this barrier. A containment vessel failure like this would result in a massive cleanup job but no leakage of nuclear material into the outside environment.
This is all moot, however, as flooding the reactor with sea water will prevent a fuel melt from progressing. TEPCO has already done this to reactor #1, and is in the process of doing it to #3. If any of the other reactors begin misbehaving, the sea water option will be available for those as well.
What was this about an explosion?
One of the byproducts of reactors like the ones at Fukushima is hydrogen. Normally this gas is vented and burned slowly. Due to the nature of the accident, the vented hydrogen gas was not properly burned as it was released. This led to a build up of hydrogen gas inside the reactor #1 building, but outside the containment vessel.
This gas ignited, causing the top of the largely cosmetic external shell to be blown off. This shell was made of sheet metal on a steel frame and did not require a great deal of force to be destroyed. The reactor itself was not damaged in this explosion, and there were only four minor injuries. This was a conventional chemical reaction and not a nuclear explosion.
You see what happened in the photo of the reactor housing. Note that other than losing the sheet metal covering on the top, the reactor building is intact. No containment breach has occurred.
At about 2:30AM GMT on March 14th, a similar explosion occurred at the reactor #3 building. This explosion was not unexpected, as TEPCO had warned that one might occur. The damage is still being assessed but it has been announced that the containment vessel was not breached and that the sea water process is continuing.
Around 7:30AM GMT on March 14th, it was announced that the explosion at reactor #2 has damaged the already limping cooling systems of reactor #2. It may also receive the sea water treatment if they are unable to use a venting procedure to restart the cooling systems.
Is there radiation leakage?
The radiation levels outside the plant are higher than usual due to the release of radioactive steam. These levels will go down and return to their normal levels, as no fuel has escaped containment.
For perspective, note that charts detailing detrimental radiation exposure start at 1 Gy, equivalent to 1 Sv; the radiation outside the problematic Fukushima reactors is being measured in micro-Svs per hour. The highest reported levels outside the Fukushima reactors has been around 1000 to 1500 micro-Svs per hour. This means that one would have to stay in this area for four to six weeks, 24 hours a day, without protection in order to experience the lowest level of radiation poisoning, which while unpleasant is not normally fatal. And this level will not stay where it is.
Also note the chart of normal radiation exposure levels from things like medical x-rays and airline flights.
There have also been very minor releases of radioactive reactor byproducts like iodine and cesium along with the steam. This material is less radioactive than the typical output of coal power plants. It is significant mainly as an indicator of the state of the reactor core.
I read that there's a plume of radioactive material heading across the Pacific.
In its current state, the steam blowing east from Japan across the pacific is less dangerous than living in Denver for a year. If it makes it across the ocean, it will be almost undetectable by the time it arrives, and completely harmless as the dangerous elements in the steam will have decayed by then.
What's this about fuel rods being exposed to the air?
When the coolant levels inside the reactor get low enough, the tops of the fuel rods will be exposed to the air inside the containment vessel. They have not been exposed to the external atmosphere and the containment vessels are all intact.
Can this end up like Chernobyl?
No, it cannot. for several reasons.
Chernobyl used graphite as a neutron moderator and water as a coolant. For complicated reasons, this meant that as the coolant heated up and converted to steam, the fission reaction intensified, converting even more water to steam, leading to a feedback effect. The Fukushima reactors use water as both the coolant and the neutron moderator, which means that as the water heats up and converts to steam, the reaction slows down instead. (The effect of the conversion of water coolant to steam on the performance of a nuclear reactor is known as the "void coefficient", and can be either positive or negative.)
Chernobyl was designed so that as the nuclear fuel heated up, the fission reaction intensified, heating the core even further, causing another feedback effect. In the Fukushima reactors, the fission reaction slows down as the fuel heats up. (The effect of heating of the nuclear fuel on the performance of a nuclear reactor is known as the "temperature coefficient", and can also be positive or negative.)
Chernobyl's graphite moderator was flammable, and when the reactor exploded, the radioactive graphite burned and ended up in the atmosphere. The Fukushima reactors use water as a neutron moderator, which is obviously not flammable.
Note that while Chernobyl used light water as a coolant (as distinct from heavy water), it was not a "light water reactor". The term LWR refers strictly to reactors that use light water for both cooling and neutron moderation.
The news said this was the worst nuclear power accident since Chernobyl, though.
It's the only nuclear power plant accident of its type since Chernobyl. It's easy to be the worst in a sample size of one.
Is this like Three Mile Island?
There are similarities. The final effect on the world is likely to be similar: no deaths, minimal external contamination, and a tremendous PR disaster for the nuclear industry due to bad reporting by the media.
How can I keep up with developments?
The western media has been very bad about reporting this event, due to a combination of sensationalist reporting, ignorance, and the use of inexact or unexplained terminology.
One of the safe sources of information is the TEPCO site, which has been posting press releases on a regular basis. Unfortunately, this site is often unresponsive due to the immense traffic it is receiving.
The important thing to remember is that most of the "experts" appearing on the news are engaging in speculation. Very few of them are restricting themselves to what they can be sure about, and those that are have often been misrepresented.
Reading:
Timeline and data sheets for the incident by the Nuclear Energy Institute : (nei.org)
The International Atomic Energy Agency is providing regular announcements
Wikipedia on light water reactors and nuclear weapon design
The United States Nuclear Regulatory Commission's Boiling Water Reactor (BWR) Systems manual - the Fukushima reactors are BWRs, a subset of LWRs (nrc.gov)
Tokyo Electric Power Company site with press releases - currently hard to reach due to traffic (tepco.co.jp/en)
Video:
"Physics for Future Presidents" lecture ten, on nuclear weapons and nuclear reactors (Youtube search)
Footage of the hydrogen explosion at reactor #1

----------------------------------------------
You're not as good as you think you are. Seriously.

[1969912 0]

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Ok, the "comment" from Sam W. - 3161669:

In the aftermath of the recent earthquake and tsunam.......

Really good info. That stuff about LWR's not being able to have a core fire like Chernobyl is all correct, but I'm a bit concerned about the apparent use of Boron as a neutron poison. Why would they do that if the reactor(s) are fully SCRAMe'd? Also of concern are the recent reports that containment (not the sheet metal buildings, but the actual reactor vessel) may have been breached. Pressure excursions due to adding water to the hot core could force some fuel/fission products out into the local environment. Again, it will be nothing like Chernobyl, but it will make a mess. My background is in low pressure fast neutron reactors that use liquid metal as a cooolant with no neutron moderator, so I'm kind of learning about LWR's as this thing unfolds. The biggest problem for me is getting accurate real-time information about what is really going on.

"Once we got to the point where twenty/something's needed a place on the corner that changed the oil in their cars we were doomed . . ."
-NickDG

[billvon 2,396]

A few notes:

>Making a nuclear bomb is very difficult, and it is completely impossible for
>a nuclear reactor to accidentally become a bomb.

Depends on the reactor. While light water reactors cannot undergo prompt criticality, other reactors (like the RBMK reactor used at Chernobyl) can. Obviously this is a bad thing.

>One of the byproducts of reactors like the ones at Fukushima is hydrogen.
>Normally this gas is vented and burned slowly.

Hydrogen is not produced in any significant quantity by normally operating light water reactors. Only when the fuel is superheated (to above 2000 degrees C) will the reactor begin to thermally dissociate water, producing hydrogen and oxygen. That's why it's a problem; reactors have no reliable methods of dealing with hydrogen production.

>They are not capable of achieving supercritical levels; the nuclear fuel
>would melt before this could occur, and a supercritical reaction is required
>for an explosion to occur.

A nuclear power plant _can_ go supercritical and often does; that's what happens when the operators are ramping up power. (Critical = just enough fission to maintain the reaction; supercritical = more fission than is needed, and thus power output is increasing.)

The term he is likely thinking of is prompt critical, which is the high school physics version of nuclear reactions. A U235 atom splits, produces neutrons, these neutrons split other atoms, which produce even _more_ neutrons etc. This can happen almost instantaneously, and is how nuclear bombs are detonated. If a reactor was designed to operate in this mode (i.e. relying entirely upon prompt neutron production) it would be very difficult to control; you'd have to react within milliseconds to keep the reactor from exploding like a bomb.

Most modern reactors are designed such that even in the worst case failure (i.e. incorrect withdrawal of all control rods) the assembly cannot go prompt critical. Instead, the reaction is maintained both by the prompt-critical neutrons (once they have been slowed down by the moderator) and by the neutrons from the decay products of the original fission. Since these release their neutrons between a tenth of a second and a minute after the original fission, it's a lot easier to control the reaction; you have tens of seconds to adjust control rods to maintain the desired level of fission.

[virgin-burner 1]

latest news, 3rd explosion occorued, no-fly zone for 30km, about 20 miles, same zone people are asked to stay inside. elevated levels of radiation can now also be measured in tokyo.

“Some may never live, but the crazy never die.”
-Hunter S. Thompson
"No. Try not. Do... or do not. There is no try."
-Yoda