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Nuclear Risk Expert: Fukushima Fuel May Be Leaking
An anonymous reader writes "Three weeks after the nuclear crisis began at Japan's Fukushima Dai-1 power plant, there's still a real danger of melted nuclear fuel escaping the reactor buildings and releasing a large dose of radiation. So says Theo Theofanous, an engineer who spent 15 years studying the risks of nuclear reactors. Theofanous believes that melted nuclear fuel has already leaked through the reactor vessels and accumulated at the bottoms of the primary containment structures. All attempts to keep the reactor buildings cool may not be enough to prevent the overheated fuel from eating through the concrete floors, he says."
MIT NSE Nuclear Information Hub
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
The information I have is that they did bring mobile generators to the site.
* Fukushima Dai-ichi units 1, 2 & 3 successfully shut down when the plant lost off-site power during the earthquake. Units 4, 5 & 6 were already offline for maintenance.
* On-site diesel backups successfully engaged to continue the cooling process, but the diesels were knocked offline when seawater from the tsunami flooded the fuel tanks. They got about an hour of cooling before these diesels were ruined.
* At that point, an backup battery supply engaged, and ran for about 8 hours before it was depleted. This is 2x the average capacity of the battery backup system at an American nuclear power plant.
* Meanwhile, they did get mobile diesels brought in, but the were only able to generate enough power to stabilize units 2 & 3. Unit 1 lost cooling water, and in 4 hours they were forced to vent the built up hydrogen gas.
* I found some discussion that the coolant pumps require 5 MW to power, which a generator at 100,000 lbs is above what even a US chopper could airlift. This is why the helicopters were focusing on transporting coolant (seawater).
* The issue then was they were physically leaking coolant water, and the rods were exposed at units 1 & 4. The exposed rods resulted in hydrogen explosions (which is what all the videos show).
* The transco's goal was to get off-site power restored, which was basically rebuilding the transmission line to a neighboring plant. It took 6 days to get it restrung.
Yes, it was that cut off.
This appears to be a very informative article. I did not know that the batteries were actually the 4th backup system:
http://www.backsidesmack.com/2011/03/explaining-the-fukushima-1-incident/
The authorities don't know how the water is leaking out and don't know the upper bound on the total amount of radioactivity released. The lower bound is already rather staggering. In addition, radioactive materials have already leaked into the ocean and the ground water. TEPCO said the level they measured in the ground water was the similar to the high levels found in the turbine buildings and the tunnels outside the plants. The Japanese Nuclear and Industrial Safety Agency said those readings were way too high so they asked TEPCO to measure again more carefully.
The only specific theory I've heard of how the thousands of tons of highly radioactive water got out of the containment vessel is that it got out via graphite seals in the bottom of the vessel. There are holes there for control rods and the holes are blocked with graphite seals. The seals will fail at high temperatures and melted fuel rods falling to the bottom of the vessel would provide more than enough heat to cause the seals to fail. If it is any solace, reactors that don't contain melted fuel rods probably don't have leaks all over the bottom of the containment vessel.
The radioactivity released at Chernobyl escaped upward into the air. This made it easier to get a handle on the magnitude of the total amount of radioactivity released. The release at the light water reactors at Fukushima is for the most part traveling downward, to basements, tunnels, ground water, and the ocean. This makes it extremely difficult to get a handle on the total amount of radioactivity that has been released. They really don't know of the bulk of it is in the thousands of tons they have already discovered or if that is just the tip of the iceberg.
We don't see the world as it is, we see it as we are.
-- Anais Nin
Burn it off with a controlled burn? How do you suggest that they do that? Light a match next to where it is coming out? It's not like they had a lot of options for the hydrogen gas with no power whatsoever on site. Also I don't know what you mean by "build the reactors along the fault line" You do realize that the fault line is in the ocean right? Not directly under Fukushima. By that reasoning, Tokai and Onagawa should not have been built either. "far lower than the historic tsunami wave-heights" where did you get this information? I can't find any data on historic wave heights of Fukushima. Don't just say "Oh there was such and such a high wave in Hokkaido" either, because the geography of the sea floor and the coast makes a big difference. They had a wall ready for a 5.5 meter tsunami, which is still a huge wave. The earthquake sunk the Japanese coast by about 1 meter AND it was hit by a 14 meter tsunami. This is documented in NOVA's documentary on the subject: http://www.pbs.org/wgbh/nova/earth/japan-killer-quake.html . Salvage the reactors? They wrote off the reactors the minute they injected them with seawater. They have publicly said that reactors 1 - 4 will never run again. There is a good deal of information out there if you speak Japanese. Otherwise, you have to wait for someone to translate it which doesn't always happen. If you don't speak Japanese then you are in no position to comment on the amount of information that is or is not coming out.
I am sick of the idiots saying "seal it". What the fuck do you think that means? The core material has most likely melted through the inner steel vessels and probably in places through the concrete containment (at least that seems likely) - as a result, highly radioactive water is leeching out into the drainage tunnels and out to the Pacific Ocean.
How exactly can you "seal" that? Furthermore, even if you could, what makes you think that sealing it before you've cooled down the corium material is a good idea? I mean, if it's been hot and radioactive enough to melt through concrete, how exactly do you "seal" it?
The whole point is it needs to be cooled down enough and stabilized so that it's not melting through anything on an ongoing basis, and only then do the existing leaks need to be sealed up as best as possible, or at least mitigated so that whatever has escaped stays relatively localized.
As for "shut it down", it was shut down within seconds of the original earthquake. It's just that it needs ongoing cooling even after shutdown for quite some time - and once the fuel rods have melted down, it needs even more cooling.
...And what power source would you recommend? Coal, which is pretty much the only other viable alternative to nuclear energy at this point, which kills over 5 thousand workers each year just mining it, not to mention all of the health risks associated with burning coal for power. On the other hand, we've had about 63 deaths occurring directly from nuclear incidents since nuclear power started. Now, while others have obviously had larger cancer risks and such resulting in death, but it is nearly impossible to be 100% certain about how many of those have occurred. Quite honestly nuclear power is the safest type of power we have at the moment.
And we have to realize that the disaster at the Fukushima plant isn't normal. Rather, this was the fifth largest earthquake to be recorded in modern history. Not only that but it had a huge tsunami to go along with it. Could TEPCO have handled this better? Yes. Could the Japanese government have handled this better? Yes. Should TEPCO have built this reactor to withstand larger earthquakes? Yes. But is nuclear power more dangerous than coal, oil, and every other power source that can be used in large quantities? No.
Taxation is legalized theft, no more, no less.
After fission, there's a whole lot more in there than uranium in there, and uranium is the least of the concerns from a radioactivity point of view.
The stuff will be a molten mix of uranium, zirconium, ceramic, steel and all sorts of other stuff, mostly the materials with high boiling temperatures. The molten core material would have the gross composition of a mix of metal and silicate rock. It's very dense and very difficult to cut up, if the melted products in the bottom of Three Mile Island are any indication. For leaching to be effective it would have to be crushed up (in order to increase the surface area and let the water percolate through) and you'd have to use a leaching solution that removes all the elements of interest. I'm not sure such a chemical solution exists. Furthermore, you have to do it at high temperatures without the introduced solution reacting with the concrete. Given how chemically reactive concrete is compared to typical metal or silicate rock, I can't think of a solution that would promptly dissolve the latter two without probably dissolving the former. Even if you were successful at selectively removing the dangerous stuff into solution, then you've got a solution full of the dangerous stuff -- a solution that can leak and escape lot easier. Worse, if it is boiling off it might even end up concentrating the radioactive solids as it evaporates and eventually could increase the nuclear reaction where the solids are concentrated.
This is not the same rock that they mine uranium from. It's a different material. This is a bad idea even if there was any chance of it actually working, which seems doubtful.
Not arguing with you, but if you're counting deaths from mining coal, you need to also count deaths from mining uranium, not just deaths from "nuclear incidents".
When our name is on the back of your car, we're behind you all the way!
it doesnt reduce radiation dose. gamma requires several feet of shielding to bring it down. the suits are just there to prevent particle contamination from getting in/on their bodies.
The energy content in one ton of uranium using 1960s reactors is roughly equivalent to 16,000 tons of coal. Using newer reactors that consume U-238 as well as U-235, a ton of uranium will produce more energy than a million tons of coal.
Assuming coal mining kills 5000 people a year and uranium mining kills as many people per ton, to produce the same amount of electricity you're looking at less than one mining death every 3 years for 1960s plants and one death every 200 years with newer plants.
Exactly. The reactor is failing through the modes it was designed for. First melting through the inner steel containment, then the outer containment shell, then sinking through a few meters of concrete, there to be dispersed harmlessly through the water table.
Pfft! And some people thought the people who engineered the thing had no plan for graceful degradation!
Oh japan.org? ... fake rads map ... fear mongering anti-nuke crap ... Good call.
Instead of a brain-dead attack on the messenger, why not try finding out the truth for yourself? It takes all of 10 seconds to go to the IAEA site here and see the numbers quoted by the OP are correct:
The average total deposition determined at these locations for iodine-131 range from 0.2 to 25 Megabecquerel per square metre and for cesium-137 from 0.02-3.7 Megabecquerel per square metre. The highest values were found in a relatively small area in the Northwest from the Fukushima Nuclear Power Plant. First assessment indicates that one of the IAEA operational criteria for evacuation is exceeded in Iitate village. We advised the counterpart to carefully assess the situation.
The world's largest concrete pump, deployed at the construction site of the U.S. government's $4.86 billion mixed oxide fuel plant at Savannah River Site, is being moved to Japan in a series of emergency measures to help stabilize the Fukushima reactors.
"Our understanding is, they are preparing to go to next phase and it will require a lot of concrete," Ashmore said, noting that the 70-meter pump can move 210 cubic yards of concrete per hour.
Putzmeister equipment was also used in the 1980s, when massive amounts of concrete were used to entomb the melted core of the reactor at Chernobyl.
"It will be too hot to come back," Ashmore said.
We don't see the world as it is, we see it as we are.
-- Anais Nin
The battery backup in commmercial nuclear plants does NOT run the large scale cooling equipment, that is what the multiple independent channels of diesel backup power (which failed along with offsite power) are for.
The battery backup is for instrumentation and control only, including computer monitoring systems, process control computers, some valves, etc. At a typical GE BWR (like fukushima, I was an operator at a newer GE BWR myself) the entire basement of the control/auxialiary building is filled with lead acid batteries (multiple THOUSANDS of car battery sized cells) and large UPS's (27 of them at the plant I worked at) for backup power to intrumentation and control only.
The RHR (recirc heat removal pumps, used for both emergency and normal shutdown cooling) are huge beasts, batteries could not possibly keep them running. They are 4160v multiple 1000 horsepower motors (can't remember exact size), no way lead acid batteries can do that (let alone the UPS's), simply no way. One easy way to vouch for this fact is that the UPS's only produced 270VAC power!
There is the HPCI and RCIC systems driven by decay heat steam from the reactor itself (via small to mid sized steam turbines), and in the fukushima situation these likely functioned until control power was lost (assuming piping to these stayed intact). After control power is lost, these systems shutdown or break, or overspeed, can't remember, probably varies with the individual plant. Either way, no control power, no HPCI or RCIC
The spent fuel pool is another matter entirely. It has a separate electric motor driven pumped cooling system, but once again, batteries do do not drive these, these pumps are something like multiple 100Hp 480v pumps, once again outside the range of what even a ton of lead acid batteries can manage for any significant length of time. (see paragraph about heat sink below too)
The loss of offsite power, followed by the loss of the diesel backup power is really the root failure, and you need BIG diesels (or gas turbines even) to manage this load. At the plant I worked at, there were 4-4+ MW diesels onsite for a single reactor. 2 at a minumum were needed to keep things cool if offsite power was lost (assuming no other failures). We had fuel for approximately 2 weeks of run time of each diesel within the control building (about 200000 gallons, with another million available in a non safety rated tank outside the buidling). 4Mw locomotive or marine sized diesels cannot be simply trucked or helicoptered in, these are BIG machines, not to mention replacement fuel (they're thirsty!). In my plant's case, each diesel was a 5000Hp, 16 cylinder twin turbocharged monster that was originally designed for use in diesel electric cargo ships!
Perhaps if they parked an aircraft carrier right on the coast and somehow ran cables that could have made up for the loss of power, or maybe a dozen or so diesel electric locomotives, a few large diesel electric container ships, etc. but nothing smaller than that could have handled this load (original design Nimitz class aircraft carriers have about 20Mw electrical generating capacity INCLUDING their 4 emergency diesel generators at 4160v 60Hz, and remember they need some of that to keep their own engine room and other ship functions operating in this sort of scenario). But even then you would need some hellish power cables and functioning switchgear and control power in the plant itself BEFORE you could consider turning on a big cooling pump
Oh yeah, you would also need a functioning "service water" system (part of the normal seawater cooling system for the plant, not the emergency seawater cooling that is being used, provides cooling water and makeup water to cooling towers at some plants), those pumps (assuming control power AND intact piping again), needs another megwatt or so to operate. If you don't have service water, you don't have a heat sink even if you get the cooling systems inside the plant building operating.
Most people have no idea of the scope of the pow