Simpsons did it.
Posted on 03/18/2011 9:33:04 PM PDT by Errant
TOKYO (MNI) - Tokyo Electric Power Co (TEPCO) has succeeded Saturday in restarting an emergency diesel generator and resuming the cooling functions in Reactors 4 and 5 in its Fukushima nuclear power facility as work continued to bring power to the other reactors.
Reactors 4 and 5 at the plant are set away from the other four reactors, which sustained the most damage in the massive quake and tsunamis on March 11.
Meanwhile, workers have succeeded in attaching a power cable to the crisis-hit Fukushima nuclear power plant and are now working inside to ensure success when they switch on desperately needed cooling machinery.
"TEPCO has connected the external transmission line with the receiving point of the plant and confirmed that electricity can be supplied," the plant's operation, TEPCO said.
(Excerpt) Read more at automatedtrader.net ...
I read that spend rods continue to generate heat due to fission by-products, but I don’t know for how long.
The grid lines work. Great. Prayers for the guys hooking up the rest.
Roger that.
I think it is proper, at some point, to recognize the heroism of the engineers that have diligently stayed at their posts at fukushima and continued to work this problem. I know they’ve been working in shifts to minimize exposure... but in any case... they’re put their mission ahead of their own interest. Remember too that many of these guys have (or had) family out in the affected areas of the earthquake / tsunami and don’t know anything about their status. Kudos to them. Bravo Zulu.
1-4 are permanently toast at this point. 5 and 6 maybe salvageable.
As another poster pointed out, this MIT site covers all the bases and updates events although very clinical in descriptions still easy to understand...
Answers to your question about spent fuel rods probably found under the heading: ‘On worst case scenarios
Posted on March 17, 2011 3:55 pm UTC by mitnse’
I also have heard nuke experts wondering why the spent fuel rods are stored on top of the reactors, cost savings for the company has been the mostly likely answer.
Sorry, on page 2 at the MIT site it
addresses spent fuel rods and their ponds directly...
Lack of room at the site, is what I have read.
Explanation of Nuclear Reactor Decay Heat
When there is a ... shutdown, the fission reactions essentially stop and the power drops drastically to about 7% of full power in 1 second. The power does not drop to zero because of the radioactive isotopes that remain from the prior fissioning of the fuel. ... The decay radiation then deposits most of its energy in the fuel, and this is what is referred to as decay heat. As these radioactive isotopes continue to decay, more and more of them reach a stable state and stop emitting radiation, and thus no longer contribute to the decay heat.See chart and table at link.
The reactor decay heat is now down to less than 0.5% of the normal power. But that is still about 10 Mega Watts of heat to remove from each reactor to maintain temperature. Even after a year it's still about 5 MW.
Spent nuclear fuel (SNF) refers to fuel after it has fueled a reactor. ... SNF contains fission products ... which are radioactive, meaning it needs to be shielded. ... The SNF also needs to be cooled, but at a much lower level than fuel in a recently (<12 hours) shutdown reactor as it produces only a fraction of the heat. In summary, the SNF is stored for a certain time to: 1) allow the fuel to cool as its decay heat decreases; and 2) shield the emitted radiation.These pools are ... often 40 feet deep ... The pools are made of thick concrete, lined with stainless steel. SNF assemblies are placed in racks at the bottom of these pools, so almost 30 feet of water covers the top of the SNF assemblies. The assemblies are often separated by plates containing boron which ensure a neutron chain reaction cannot start. The likelihood of such an event is further reduced because the useful uranium in the fuel has been depleted when it was in the reactor, so it is no longer capable of sustaining a chain reaction. ... The heat is rejected through a heat exchanger in the pool so the pool should stay at fairly constant average temperature. The water depth also ensures the radiation emitted from the SNF is shielded to a level where people can safely work around the pools.
Just so you all can sleep well at night. Since Carter cut off the reprocessing of spent fuel rods and since Obama wouldn’t allow Yucca Flats to be activated, all spent fuel rods from the last 25 years of operation are still sitting in similiar pools at US plants. Not secure inside a containment vessel.
I think it's just an old design. At the link I posted above it explains that they flood the area between the spent fuel pool and the reactor core with water to move fuel into and out of the core. So proximity is needed during this phase.
Newer designs may have below ground level storage for spent fuel.
I've also seen speculation that the pools that are heating up may have small water leaks causing the loss of cooling water.
Amen!
Newer designs still have the spent fuel pool at an elevation that allows a horizontal transfer of the fuel rods between the reactor and the fuel pool.
Likely because the reactors are loaded and unloaded from the top.
So the top is where they are stored. For example reactor 4 was unloaded for maintenance, all the rods were in the storage pool. Having to move the rods a long distance to store them elsewhere would likely greatly increase the possibility of an accident while moving them.
That said, on top still seems dangerous... A melt down in the pool melts down to the reactor below. Though on the other hand, a melt down in the pool is probably worse than a meltdown in the reactor... There’s more fuel in the pool...
Those reactor cube buildings are about 150’ wide (or half a football field) to give some perspective... That’s pretty darn large...
Optimus Prime (Peter Cullen) said that in the animated Transformers movie in 1986. Love that line.
Simpsons did it.
These pools also store fuel that is not spent. When reactors are shut down for maintenance the fuel is temporarily stored in these pools while the reactor is being worked on.
Reactor #4 is a case and point. It was shut down for maintenance and its fuel rods stored in the adjacent pool above it.
sensationalism equals ratings—its as simple as that.
Earthquake zone is why the rods are above...concern that in ground could fracture the container....or something like that....There was a piece about why they opted for above ground.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.