Posted on 03/14/2011 12:54:09 AM PDT by SteveH
At the 40-year-old Fukushima Daiichi unit 1, where an explosion Saturday destroyed a building housing the reactor, the spent fuel pool, in accordance with General Electric’s design, is placed above the reactor. Tokyo Electric said it was trying to figure out how to maintain water levels in the pools, indicating that the normal safety systems there had failed, too. Failure to keep adequate water levels in a pool would lead to a catastrophic fire, said nuclear experts, some of whom think that unit 1’s pool may now be outside.
Victor Gilinsky, a former commissioner at the Nuclear Regulatory Commission, said that to produce hydrogen, temperatures in the reactor core had to be well over 2,000 degrees and as high as 4,000 degrees Fahrenheit. He said a substantial amount of fuel had to be exposed at least at some point.
“That’s the significance of the hydrogen — it means there was serious fuel damage and probably melting,” said Gilinsky, who was at the NRC when Pennsylvania’s Three Mile Island reactor had a partial meltdown in 1979. “How much? We won’t know for a long time. At TMI we didn’t know for five years, until the vessels were opened. It was a shock.”
(Excerpt) Read more at washingtonpost.com ...
They need to take care of their people right now IMO.
Can’t hardly sleep myself knowing the staus there...imagine those in Japan! They have evacted thousands already but Japan itself as a whole is in danger as well...
They still have a chance of pulling a rabbit out of their hats. And perhaps they are the most capable nation on the planet suited to deal with these problems. Will be a long drawn out battle while the reactors slowly cool off.
The people need to be taken care of. The headlines/bull$hit might scare me off.
Even when the rods are spent under normal conditions..they have to be stored in cooling water....these rods take years to cool.
Anyone know how the spent rod pools were stored in Reactor #3 ?
No, there are doing what they have been trained to do and there isn't going to be another Chernobyl.
It's time for everyone to shake their adrenalin addiction.
Well it is being reported that the 2nd reactor is now running low on coolant. Its cooling system has failed. Sea water is to be dumped in that one too.
It’s been done with coolant for awhile now...began earlier to use seawater...terrible all three reactors in danger.
Some have also mentioned the fact that the spent fuel pools (not sure if they have them on site at any of these plants) also need to be kept cool and rely on circulating water (pumps) to keep them cool. If those pumps fail in several days they can get hot enough to turn the water into steam, and eventually they can get hot enough to melt down - only difference is they are not in a containment vessel, they will just release right out in the open.
Well look at the bright side. we still have 3 more after those. Six reactors at that site. Four are grouped together and two more are grouped a little ways away. I believe that at one time they had problems with #6.
You would not believe the work I have on my plate right now, and if we do end up with radiation fears in the US, it will cause many business problems. The last thing we want is the worse case scenario. All we are doing is trying to find out what the heck is going on. Why that deserves criticism is beyond me.
I agree. Reminds me of the Apollo 13 quote about this not being our worst disaster, but instead this will be our finest moment.
Only they could simply run a fire hose in from the ocean, and one out back to the ocean. And I bet they would do it too, if it came to that.
I had heard they had the fire department pumper vehicles in there to help with getting water into the units.
http://library.thinkquest.org/17940/texts/nuclear_waste_storage/nuclear_waste_storage.html
Nuclear Waste Storage
Introduction:
The major problem of nuclear waste is what to do with it. In fact, one of the biggest (and perhaps the single biggest) expenses of the nuclear power industry could eventually be the storage of nuclear waste. Currently there are several ways in which nuclear waste is stored. Most of these methods are temporary. In most cases a viable long-term solution for waste storage has yet to be found. This is because the time period for storage is so incredibly long, on the order of thousands of years.
Temporary Storage of Fuel Rods:
[photo]
Fuel Rod Storage Pool
Picture of a Temporary Fuel Rod Storage Pool
Photo Used With Permission of Joseph Gonyeau. Original Source: Virtual Nuclear Tourist
The spent fuel rods from a nuclear reactor are the most radioactive of all nuclear wastes. When all the radiation given off by nuclear waste is tallied, the fuel rods give off 99% of it, in spite of having relatively small volume. There is, as of now, no permanent storage site of spent fuel rods. Temporary storage is being used while a permanent site is searched for and prepared.
When the spent fuel rods are removed from the reactor core, they are extremely hot and must be cooled down. Most nuclear power plants have a temporary storage pool next to the reactor. The spent rods are placed in the pool, where they can cool down. The pool is not filled with ordinary water but with boric acid, which helps to absorb some of the radiation given off by the radioactive nuclei inside the spent rods. The spent fuel rods are supposed to stay in the pool for only about 6 months, but, because there is no permanent storage site, they often stay there for years. Many power plants have had to enlarge their pools to make room for more rods. As pools fill, there are major problems. If the rods are placed too close together, the remaining nuclear fuel could go critical, starting a nuclear chain reaction. Thus, the rods must be monitored and it is very important that the pools do not become too crowded. Also, as an additional safety measure, neutron-absorbing materials similar to those used in control rods are placed amongst the fuel rods. Permanent disposal of the spent fuel is becoming more important as the pools become more and more crowded.
Dry Cask Storage Containers
[photo] Picture of a Dry Cask
Used with Permission of NSP
Another method of temporary storage is now used because of the overcrowding of pools. This is called dry storage (as opposed to "wet" storage which we outlined above). Basically, this entails taking the waste and putting it in reinforced casks or entombing it in concrete bunkers. This is after the waste has already spent about 5 years cooling in a pool. The casks are also usually located close to the reactor site.
Permanent Fuel Storage/Disposal:
There are many ideas about what to do with nuclear waste. The low-level (not extremely radioactive) waste can often be buried near the surface of the earth. It is not very dangerous and usually will have lost most of its radioactivity in a couple hundred years. The high-level waste, comprised mostly of spent fuel rods, is harder to get rid of. There are still plans for its disposal, however. Some of these include burying the waste under the ocean floor, storing it underground, and shooting it into space. The most promising option so far is burying the waste in the ground. This is called "deep geological disposal". Because a spent fuel rod contains material that takes thousands of years to become stable (and non-radioactive), it must be contained for a very long time. If it is not contained, it could come in contact with human population centers and wildlife, posing a great danger to them. Therefore, the waste must be sealed up tightly. Also, if the waste is being stored underground, it must be stored in an area where there is little groundwater flowing through. If ground water does flow through a waste storage site, it could erode the containment canisters and carry waste away into the environment. Additionally, a disposal site must be found with little geological activity. We don't want to put a waste disposal site on top of a fault line, where 1000 years in the future an earthquake will occur, releasing the buried waste into the environment.
The waste will probably be encapsulated in large casks designed to withstand corrosion, impacts, radiation, and temperature extremes. Special casks will also have to be used to transfer fuel rods from their holding pools and dry storage areas next to the reactor to the permanent geological storage site.
Aerial view of Yucca Mountain and the dry region around it
Image Courtesy Yucca Mountain Site Characterization Process
In the US a permanent storage site has been selected at Yucca Mountain, Nevada. Yucca Mountain is in an extremely dry area of Nevada. This minimizes the possibility of water seeping through the rock and corroding the casks. Additionally, if the casks do get corroded, there is not much water flow to carry the nuclear wastes away. The casks will be buried about 1500 feet underground, further preventing the waste from escaping. It is also far from the nearest population center in Las Vegas. While Yucca Mountain is near of a fault line, the fault is believed to be inactive. There are several volcanoes in the vicinity, but scientists believe that they have been dormant for almost a million years and think it unlikely that they will erupt in the next 10,000 years. Naturally, the people in Nevada are opposed to the creation of a nuclear waste repository. They express the common reaction, NIMBY (Not In My Backyard!!). This is because that although most evidence indicates that Yucca Mountain is a suitable place for storage, no one can guarantee that waste will not leak. However, quite a bit of research has already conducted around the Yucca site. Also, work on tunneling into the mountain has been started. The Yucca Mountain Deep Geological Repository is projected to be ready by the year 2010.
[photo]
The Massive TBM (Tunnel Building Machine) Used to Dig the Tunnels Into Yucca Mountain
Picture of the extremely large machine used to dig the tunnels into Yucca, posed next to a car which it dwarfs
Image Courtesy Yucca Mountain Site Characterization Process
[photo] One of the Storage Tunnels
Picture of one of the immense tunnels which have been carved into Yucca Mountain to store nuclear waste
Image Courtesy Yucca Mountain Site Characterization Process
Nuclear Waste (types) Nuclear Waste (future) Developed By Students for Thinkquest © Thinkquest 98, Team 17940 All Rights Reserved
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