So anywhere the population moves a lot should not have nuclear power?
Japan, nuclear power plant situation. Your thoughts.
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thatoneguy
- Joined Feb 19, 2009
- 6,359
If you look at all the reactors that were hit and SURVIVED, that shows how well engineered and well built these are.
There is a nearly identical plant that was hit with the quake, but a lower Tsunami a dozen or two miles south of the effected plant. Sensors automatically SCRAMmed the plant when the quake hit, they had cooling problems on days 1 and 2 after, but got connected to offsite power quickly, and are now a non-issue.
There's a dozen other reactors around Japan providing power, a few are offline for double and triple checking, hence the cut down power (no advertising signs glowing all over Tokyo). Inside buildings, it is business as usual. Even some of the major roads that were torn up from the quake have been resurfaced. The Japanese bounce back faster than any other country I've seen a disaster at, including the US.
There is news of radiation dosage of about 1000ms near the turbine area. Which indicates the probability of partial meltdown. I was wondering about two things.
1. Since there were explosions which even blew of the concrete roof top, does it not in itself indicate that reactor core/ containment vessel was damage as well?
2. Could they not have used some sort of android/automated surveillance/_*(insert appropriate term here) system for some form of assessment of damage to core?
1. Since there were explosions which even blew of the concrete roof top, does it not in itself indicate that reactor core/ containment vessel was damage as well?
2. Could they not have used some sort of android/automated surveillance/_*(insert appropriate term here) system for some form of assessment of damage to core?
The hydrogen gas blew the containment vessel, which is not a indicator of melt down. The extreme heat cause the hydrogen/oxygen problem, related to but not electrolysis.
Given that Japan can probably qualify as the robotics capital of the world, it is predictable that there will be robots and other machines developed specifically to clean up the mess.
They are finding radiation in some odd places, this is probably more indicative of meltdown than anything else. We'll just have to wait and see what news comes out.
Given that Japan can probably qualify as the robotics capital of the world, it is predictable that there will be robots and other machines developed specifically to clean up the mess.
They are finding radiation in some odd places, this is probably more indicative of meltdown than anything else. We'll just have to wait and see what news comes out.
I wasn't referring to the explosion as an indication of meltdown, rather about it damaging the containment or core. As the explosion products (gas and else) came out of the building, did it not indicate damage to core and exposure of fuel rods to atmosphere?
Robots for clean up may be more expensive(or time taking). I am pretty sure they are going to go for a Chernobyl-like solution at least for a couple of reactors. What i wanted to know is if they could have used it for visual inspection of the reactor cores. It is surely not something they might not have thought of. I do not think it would be so hard to send a robot (or a remote controlled bot) inside the building for inspection. Though the personnels have gone upto the control room now, but isn't the idea much more safer?
Robots for clean up may be more expensive(or time taking). I am pretty sure they are going to go for a Chernobyl-like solution at least for a couple of reactors. What i wanted to know is if they could have used it for visual inspection of the reactor cores. It is surely not something they might not have thought of. I do not think it would be so hard to send a robot (or a remote controlled bot) inside the building for inspection. Though the personnels have gone upto the control room now, but isn't the idea much more safer?
Generally control rooms are the safest part of the plants, best shielded, most monitored. They are not going to be abandoned. The explosion occurred at the top of the containment vessel. Given this is a predicted hazard, I would be very surprised to find they didn't design for it, and not have the strongest part where it is needed at the bottom. These are highly engineered artifacts with a long history.
Well, I am not sure about nuclear plants, but i have worked in thermal power plants and the control rooms are just next to TG sets there.
I was thinking since the Hydrogen led explosion , as a result of reaction in the core and since the explosion blew even the building roof off, it definitely means now fuel cells were now exposed to atmosphere (if not covered under water). But then still there are talks about 'chances of core damage'. Isn't that damaged already with the top blown off? Also, if so, would running pumps be still harder as all the pumped water (at higher pressure) would only flow out of reactor into the surrounding?
I was thinking since the Hydrogen led explosion , as a result of reaction in the core and since the explosion blew even the building roof off, it definitely means now fuel cells were now exposed to atmosphere (if not covered under water). But then still there are talks about 'chances of core damage'. Isn't that damaged already with the top blown off? Also, if so, would running pumps be still harder as all the pumped water (at higher pressure) would only flow out of reactor into the surrounding?
The core problem, as I understand it, has been the lack of electricity to keep the critical water pump working. No water flow, you get overheating. Even with the core exposed, which was definitely the case in Chernobyl, but I don't think occurred in the Japanese reactors, water is a fundamental requirement. Indeed, one of the major design flaws for the Russian design is lack of water cooling.
With the Japanese reactor the reactor was breached, but not the containment vessel, they are two different things.
With the Japanese reactor the reactor was breached, but not the containment vessel, they are two different things.
Pun intended?
I believe the problem was the same with Fukushima reactors. No passive cooling. Which is why some of the fuel rods were feared to have been exposed to atmosphere and to have melted.
What i just don't get is, if there is an explosion of that magnitude and where products of explosion (even some radioactive stuff IIRC- correct me if I am wrong) came out does it not automatically mean a a damage to containment vessel and core and whatever other covering they had installed over it? Is that not a breach?
The containment vessel was not breached, and it is separate from the reactor. Only the Japanese know how bad it is there. The containment vessel is there just for this contingency.
One of the common scenarios of meltdowns is the molten fuel melts deep into the groundwater. At this point it has melted through many 10's of feet of concrete, which is part of the containment vessel. Last I've heard this has not happened. However, they are finding highly radioactive iodine in the ocean. If I understand this correctly, the iodine in question is a product of the fission, and is relatively short lived. In other words, it came from the core.
Being exposed to atmosphere in and of itself is not a meltdown. Taint good though.
So like I've said, we'll have to wait to hear from the Japanese government how bad it really is.
Come to think of it, dropping sea water on the core would say the containment has been breached. So I don't know.
One of the common scenarios of meltdowns is the molten fuel melts deep into the groundwater. At this point it has melted through many 10's of feet of concrete, which is part of the containment vessel. Last I've heard this has not happened. However, they are finding highly radioactive iodine in the ocean. If I understand this correctly, the iodine in question is a product of the fission, and is relatively short lived. In other words, it came from the core.
Being exposed to atmosphere in and of itself is not a meltdown. Taint good though.
So like I've said, we'll have to wait to hear from the Japanese government how bad it really is.
Come to think of it, dropping sea water on the core would say the containment has been breached. So I don't know.
thatoneguy
- Joined Feb 19, 2009
- 6,359
The only place where the actual core is an issue is reactor #2. 1 and 3 also had partial meltdowns/fuel damage, but #2 has a possibly breached containment, no worries, it has 10 feet of concrete under it, which is sitting on bedrock, containment will not be lost.
The major releases and first efforts up until this past week have been dealing with the spent fuel pools in the buildings. Nuclear fuel is used for 3 cycles in a reactor core, and they are swapped out at the top of the reactor pressure vessel (RPV, contains the actual "core").
This pool is contained by about 15 feet of water over it, a 25 ft x 25 ft x 50 ft "pond", with a gate that allows access to the reactor so the fuel is never out of water while refueling.
In all the blown up reactors, the spent fuel pool was the source of the hydrogen, the water level fell below the top of the fuel rods. The Zircalloy cladding releases hydrogen when hot.
The SFPs have all been contained now, and better measurements and inspections are being done. The reactor with the most damage happens to be #2, which didn't have the "weather containment" blown off in a hydrogen explosion. The actual containment for the reactor uses concrete 5-8 feet thick, with 2" steel lining as a bio shield. This is in addition to the 2" thick steel reactor pressure vessel.
In reactor #2, the "torus"/supression pool under the reactor, which cools excess steam for recirculation was ruptured in an apparent underground hydrogen explosion. The torus and drywell around it are built into the bedrock, so the materials are still very well contained. The majority of the radiation in all reactors is from Iodine-131, which has a 7 day half-life, meaning it will be nearly gone in 2 months. The other major decay product crews are running into is cesium, it has a much longer half-life.
This will most likely end as Three Mile Island did for the number 2 reactor, possible entombment for decay products to cool off before fully de-fueling the reactor in a few years. Reactors 5 and 6, not usually shown in the photos are fine, they were a bit higher elevation and in cold/shutdown state when the quake hit.
Reactor #4 had no fuel in the core when the quake hit, it was the biggest hazard, however, due to the amount of fuel in the spent fuel pool, a result of the core being de-fueled (fuel rods had to go somewhere when taken out of the core). None of reactors 1-4 will be run again, they are write-offs. 5 and 6 are potentially operable, but not until the accident is fully cleaned to safe levels.
I don't imagine many new surprises from this, top nuclear accident experts and equipment from around the world are onsite, and power has been returned. The current task is to verify/repair all monitoring equipment damaged by the quake/tsunami. This is what caused two workers to be exposed to higher radiation levels from the #2 reactor water (not deadly levels, but higher dose than the allowed 250mS/day). Now that that fact is known, there isn't much new that will happen.
The design of the BWR is run in the US and worldwide. PWR, the pressurized "version" of the Boiling Water Reactor, are common as well, with a similar design. The Japan incident is going to Greatly change how spent fuel is stored and handled while refueling a reactor, and possibly a new containment retrofit for all spent fuel pools with several redundant cooling systems.
Considering these reactors were designed and built in the 60s and 70s, and designed for the maximum predicted quake of 8.3 with 7 meter tsunami, they weathered remarkably well through a 9.0/9.1 quake and 8-10 meter tsunami.
Current "State of the Art" reactors could withstand what happened in Japan with little or no intervention. They nearly all have negative void coefficients, meaning if the moderator/coolant isn't there, the reaction stops quickly, leaving only the decay heat (decay heat is the problem in Japan).
The big advances have been in heat sinking, even to earth/dirt, in an emergency, so a Generation IV reactor would have virtually no chance of a meltdown. A company is selling "neighborhood reactors", that can be installed underground, supplying 25MW to an area. Requires zero intervention to run, it has no moving parts. Search for "Hyperion Reactors". We've come a long way in energy production.
When we realize that electricity is the biggest reason we have the quality of life that we do, worldwide, means we need to turn to new power sources. Nuclear is clean and reliable power. I'd have no problem living next to one, if the other option was being without power completely.
The major releases and first efforts up until this past week have been dealing with the spent fuel pools in the buildings. Nuclear fuel is used for 3 cycles in a reactor core, and they are swapped out at the top of the reactor pressure vessel (RPV, contains the actual "core").
This pool is contained by about 15 feet of water over it, a 25 ft x 25 ft x 50 ft "pond", with a gate that allows access to the reactor so the fuel is never out of water while refueling.
In all the blown up reactors, the spent fuel pool was the source of the hydrogen, the water level fell below the top of the fuel rods. The Zircalloy cladding releases hydrogen when hot.
The SFPs have all been contained now, and better measurements and inspections are being done. The reactor with the most damage happens to be #2, which didn't have the "weather containment" blown off in a hydrogen explosion. The actual containment for the reactor uses concrete 5-8 feet thick, with 2" steel lining as a bio shield. This is in addition to the 2" thick steel reactor pressure vessel.
In reactor #2, the "torus"/supression pool under the reactor, which cools excess steam for recirculation was ruptured in an apparent underground hydrogen explosion. The torus and drywell around it are built into the bedrock, so the materials are still very well contained. The majority of the radiation in all reactors is from Iodine-131, which has a 7 day half-life, meaning it will be nearly gone in 2 months. The other major decay product crews are running into is cesium, it has a much longer half-life.
This will most likely end as Three Mile Island did for the number 2 reactor, possible entombment for decay products to cool off before fully de-fueling the reactor in a few years. Reactors 5 and 6, not usually shown in the photos are fine, they were a bit higher elevation and in cold/shutdown state when the quake hit.
Reactor #4 had no fuel in the core when the quake hit, it was the biggest hazard, however, due to the amount of fuel in the spent fuel pool, a result of the core being de-fueled (fuel rods had to go somewhere when taken out of the core). None of reactors 1-4 will be run again, they are write-offs. 5 and 6 are potentially operable, but not until the accident is fully cleaned to safe levels.
I don't imagine many new surprises from this, top nuclear accident experts and equipment from around the world are onsite, and power has been returned. The current task is to verify/repair all monitoring equipment damaged by the quake/tsunami. This is what caused two workers to be exposed to higher radiation levels from the #2 reactor water (not deadly levels, but higher dose than the allowed 250mS/day). Now that that fact is known, there isn't much new that will happen.
The design of the BWR is run in the US and worldwide. PWR, the pressurized "version" of the Boiling Water Reactor, are common as well, with a similar design. The Japan incident is going to Greatly change how spent fuel is stored and handled while refueling a reactor, and possibly a new containment retrofit for all spent fuel pools with several redundant cooling systems.
Considering these reactors were designed and built in the 60s and 70s, and designed for the maximum predicted quake of 8.3 with 7 meter tsunami, they weathered remarkably well through a 9.0/9.1 quake and 8-10 meter tsunami.
Current "State of the Art" reactors could withstand what happened in Japan with little or no intervention. They nearly all have negative void coefficients, meaning if the moderator/coolant isn't there, the reaction stops quickly, leaving only the decay heat (decay heat is the problem in Japan).
The big advances have been in heat sinking, even to earth/dirt, in an emergency, so a Generation IV reactor would have virtually no chance of a meltdown. A company is selling "neighborhood reactors", that can be installed underground, supplying 25MW to an area. Requires zero intervention to run, it has no moving parts. Search for "Hyperion Reactors". We've come a long way in energy production.
When we realize that electricity is the biggest reason we have the quality of life that we do, worldwide, means we need to turn to new power sources. Nuclear is clean and reliable power. I'd have no problem living next to one, if the other option was being without power completely.
Which is what I wanted to point since that was made possible by the explosion if I am not wrong. since, the containment vessel houses the reactor.
However,
If this is the case then perhaps the core might not have been damaged. But if this was the case wouldn't the first explosion be at reactor 4? (if the fuel rods were kept in spent fuel pools--would they be?). Also, since the power has not yet been restored to the pumps isn't it more probable that the explosion might have been from the reactor instead?
I am not sure but I think, its the enrichment of fuel that also plays a major part. In PHWR (CANDU) which uses naturally occurring uranium as fuel, if Heavy water (moderator and coolant) is not there then reaction not only becomes sub critical but also the level of radiation is also low. It might be the higher decay heat of the enriched fuel which is a cause of concern.
I wonder how they effect those passive cooling system (natural circulation?). Can these passive cooling really in effect replace those powerful pumps?
thatoneguy
- Joined Feb 19, 2009
- 6,359
The core is damaged in 1-3, I am talking about fuel damage, not containment vessel. The fuel bundles may be melted together, making removal difficult. In reactor #2, containment/primary pressure vessel is surely the issue, and slightly suspected in 1 and 3. 4 had no fuel in the core, only the spent fuel pool, once it was covered with water, and cooling persists, the danger of the incident being worse in #4 is gone.
[/quote]
I am not sure but I think, its the enrichment of fuel that also plays a major part. In PHWR (CANDU) which uses naturally occurring uranium as fuel, if Heavy water (moderator and coolant) is not there then reaction not only becomes sub critical but also the level of radiation is also low. It might be the higher decay heat of the enriched fuel which is a cause of concern.
[/quote]
The MOX fuel used in #3 doesn't play at all in this scenario. Plutonium is a fission product of Uranium, which is how we amassed as much Plutonium as we did for weapons. What is being done now is small amount of weapons grade plutonium is added into the uranium fuel "pellets", so they cannot be used as a weapon, and still provide fuel. After 3 months of operation, both MOX fuel and standard Uranium fuel will have the same amount of plutonium remaining, and very similar fission products. MOX only adds extra heat during the first month or so, and not a whole lot. The plutonium allows lower grades of uranium to be used in the plant. Light water reactors need some "enrichment" to sustain a reaction. CANDU/heavy water reactors can sustain a reaction with natural uranium, but the fission products still exist.
The pumps in the BWR and PWR designs are all powered. There are several emergency circulating pumps that are designed to run from decay heat to keep the coolant moving. The rest are electric. The electric pumps are massive, think thousands of gallons of water per SECOND. They are in the range of 400 horsepower, running at 4,000 volts, so power for them isn't an extension cord away. The reason they are not running at the moment is that every electronic and electric circuit is being checked before applying power, to prevent the situation from degrading quickly. If the majority of the pumps are intact, (they aren't, a couple have been replaced from what I've read, which delays the start of cooling), they will be powered on until the decay heat is fully removed.
This will NOT be a slow cleanup. There are several million gallons of contaminated water to deal with, in addition to the structures and areas around them where radioactive decay products from the explosions were scattered, not much at all (relative to Chernobyl), but above what is desired (none).
There won't be much news, or I should say as rapidly changing/fluid situation as we've seen in the past few weeks. The site is stabilizing and getting more stable each day. Once all fluctuations in readings stop, we know it is under control, and real cleanup and containment solutions will be put to the think tanks. They may simply let reactors 1 and 3 "idle" with cooling water until they engineer a way to remove the core. I am not sure what they are going to do with number 2. I'm nearly positive that reactors 5 and 6, while ready for restart if fuel is added, won't be used for power until 1-4 are fully contained and site is back to background radiation levels (same as we did with Three Mile Island, one reactor is still providing power to the area).
thatoneguy
- Joined Feb 19, 2009
- 6,359
The MOX fuel used in #3 doesn't play at all in this scenario. Plutonium is a fission product of Uranium, which is how we amassed as much Plutonium as we did for weapons. What is being done now is small amount of weapons grade plutonium is added into the uranium fuel "pellets", so they cannot be used as a weapon, and still provide fuel. After 3 months of operation, both MOX fuel and standard Uranium fuel will have the same amount of plutonium remaining, and very similar fission products. MOX only adds extra heat during the first month or so, and not a whole lot. The plutonium allows lower grades of uranium to be used in the plant. Light water reactors need some "enrichment" to sustain a reaction. CANDU/heavy water reactors can sustain a reaction with natural uranium, but the fission products still exist.
The pumps in the BWR and PWR designs are all powered. There are several emergency circulating pumps that are designed to run from decay heat to keep the coolant moving. The rest are electric. The electric pumps are massive, think thousands of gallons of water per SECOND. They are in the range of 400 horsepower, running at 4,000 volts, so power for them isn't an extension cord away. The reason they are not running at the moment is that every electronic and electric circuit is being checked before applying power, to prevent the situation from degrading quickly. If the majority of the pumps are intact, (they aren't, a couple have been replaced from what I've read, which delays the start of cooling), they will be powered on until the decay heat is fully removed.
This will NOT be a slow cleanup. There are several million gallons of contaminated water to deal with, in addition to the structures and areas around them where radioactive decay products from the explosions were scattered, not much at all (relative to Chernobyl), but above what is desired (none).
There won't be much news, or I should say as rapidly changing/fluid situation as we've seen in the past few weeks. The site is stabilizing and getting more stable each day. Once all fluctuations in readings stop, we know it is under control, and real cleanup and containment solutions will be put to the think tanks. They may simply let reactors 1 and 3 "idle" with cooling water until they engineer a way to remove the core. I am not sure what they are going to do with number 2. I'm nearly positive that reactors 5 and 6, while ready for restart if fuel is added, won't be used for power until 1-4 are fully contained and site is back to background radiation levels (same as we did with Three Mile Island, one reactor is still providing power to the area).[/QUOTE]
(I gave up trying to fix quotes)
thatoneguy
- Joined Feb 19, 2009
- 6,359
Latest report Page 6 shows status of ALL Japanese Nuclear power plants, an impressive number.
The report is color coded, so you can see where the real damage is, with Reactor #2 being the worse of the lot (containment breach). The spent fuel pools that are on "top" (level you see on reactor 1 where the weather sheild blew off) are seriously hampering efforts. The SFPs are the reason trucks are spraying water on/into the tops of the bulidings, to keep the spent fuel covered in water. Runoff from that spraying carries away radioactive particles, which have now leaked into the turbine buliding via the #2 reactor.
There are some FLIR images that show the hot spots out there as well, the US Military has had a global hawks overhead getting all sorts of information, most of it isn't public, but a few shots are.
If you don't mind reading a lot, including smart ass comments, there's two threads on a gun forum that covers this from the minute it started, first one is 100 pages and locked (100 page site limit), the second one is at 80 some pages, with 50 posts per page, mostly information and images. Input and analysis by a couple nuke guys as well. Some language not family friendly, excellent info from beginning of earthquake
The report is color coded, so you can see where the real damage is, with Reactor #2 being the worse of the lot (containment breach). The spent fuel pools that are on "top" (level you see on reactor 1 where the weather sheild blew off) are seriously hampering efforts. The SFPs are the reason trucks are spraying water on/into the tops of the bulidings, to keep the spent fuel covered in water. Runoff from that spraying carries away radioactive particles, which have now leaked into the turbine buliding via the #2 reactor.
There are some FLIR images that show the hot spots out there as well, the US Military has had a global hawks overhead getting all sorts of information, most of it isn't public, but a few shots are.
If you don't mind reading a lot, including smart ass comments, there's two threads on a gun forum that covers this from the minute it started, first one is 100 pages and locked (100 page site limit), the second one is at 80 some pages, with 50 posts per page, mostly information and images. Input and analysis by a couple nuke guys as well. Some language not family friendly, excellent info from beginning of earthquake
thatoneguy
- Joined Feb 19, 2009
- 6,359
Found this image. This is a photo of a BWR being installed. The "upside down lightbulb" is the actual reactor chamber. The torus/donut at the base is the supression pool to keep pressures in check by converting steam back to water.
Around this lightbulb and torus are between 5 and 8 feet of pre-stressed, extremely reinforced concrete (2" rebar at 12" spacing in 4 areas throughout the 5-8' concrete containment. The outside is then again covered with 2" steel for biological shielding. This structure is then built out about 75 feet per side from the central pressure vessel, where the spent fuel pools are added. Control room is on "ground level", which is about even with where the pipes leading down to the torus are in this pre-contained image (from construction). This is to give you an idea of how much shielding there is, how reinforced it is, etc. The amount underneath the reactor makes the primary containment seem like origami.
This is what is sitting below ground level in the images from Japan. The spent fuel pool is at the same level as the "lid" in the picture, which is about 3 stories up from ground level, while the torus/donut is 2-3 stories below ground level.
The damage seen in Japan has been the "weather shield" on #1, which is somewhat strong, but meant to blow off to protect primary containment (think fuse). #3 and #4 suffered more severe explosions, where the 4th floor was damaged, leaving the rebar showing. The issues are the spent fuel pools on the 3rd floor in the "exposed" reactors, and in the torus/donut on the number 2 reactor. That is the latest very scientific guess by many experts, anyway.
Look at guy lower-center-left, standing on the torus, to get an idea of scale. Only about half of the reactor is "above ground".
Around this lightbulb and torus are between 5 and 8 feet of pre-stressed, extremely reinforced concrete (2" rebar at 12" spacing in 4 areas throughout the 5-8' concrete containment. The outside is then again covered with 2" steel for biological shielding. This structure is then built out about 75 feet per side from the central pressure vessel, where the spent fuel pools are added. Control room is on "ground level", which is about even with where the pipes leading down to the torus are in this pre-contained image (from construction). This is to give you an idea of how much shielding there is, how reinforced it is, etc. The amount underneath the reactor makes the primary containment seem like origami.
This is what is sitting below ground level in the images from Japan. The spent fuel pool is at the same level as the "lid" in the picture, which is about 3 stories up from ground level, while the torus/donut is 2-3 stories below ground level.
The damage seen in Japan has been the "weather shield" on #1, which is somewhat strong, but meant to blow off to protect primary containment (think fuse). #3 and #4 suffered more severe explosions, where the 4th floor was damaged, leaving the rebar showing. The issues are the spent fuel pools on the 3rd floor in the "exposed" reactors, and in the torus/donut on the number 2 reactor. That is the latest very scientific guess by many experts, anyway.
Look at guy lower-center-left, standing on the torus, to get an idea of scale. Only about half of the reactor is "above ground".
Hello,
Some robots seem to have entered the nuclear power plant and showed the inside:
http://www.computerworld.com/s/arti...bots_saw_Inside_Fukushima_nuclear_power_plant
Bertus
Some robots seem to have entered the nuclear power plant and showed the inside:
http://www.computerworld.com/s/arti...bots_saw_Inside_Fukushima_nuclear_power_plant
Bertus
