Six Years After Fukushima, Robots Finally Find Its Reactors' Melted Uranium Fuel (gizmodo.com)

An anonymous reader quotes Gizmodo: Earlier this year, remotely piloted robots transmitted what officials believe was a direct view of melted radioactive fuel inside Fukushima Daiichi Nuclear Power Plant's destroyed reactors [YouTube] -- a major discovery, but one that took a long and painful six years to achieve... Japanese officials are now hoping that they can convince a skeptical public that the worst of the disaster is over, the New York Times reported, but it's not clear whether it's too late despite the deployment of 7,000 workers and massive resources to return the region to something approaching normal.

Per the Times, officials admit the recovery plan -- involving the complete destruction of the plant, rather than simply building a concrete sarcophagus around it as the Russians did in Chernobyl -- will take decades and tens of billions of dollars. Currently, Tepco plans to begin removing waste from one of the three contaminated reactors at the plant by 2021, "though they have yet to choose which one"... Currently, radiation levels are so high in the ruined facility that it fries robots sent in within a matter of hours, which will necessitate developing a new generation of droids with even higher radiation tolerances.
Friday a group of Japanese businesses and doctors sued General Electric of behalf of 150,000 Japanese citizens, saying their designs for the Fukushima reactors were reckless and negligent.

Comments

Fukushima was older than Chernobyl

[jez9999]

I always like to remind people that this thing was older than Chernobyl. This was NOT a modern nuke plant with decent safety features that went meltdown. There is no comparison.

Re:Fukushima was older than Chernobyl

[interkin3tic]

Holy cow, I thought you were trolling! Thank you!

Re:Fukushima was older than Chernobyl

[Anonymous Coward]

I like to remind people that practically all nuke plants are old and don't have decent safety standards, and that it will always be this way because nobody likes to decommission an expensive nuclear power plant if it can be kept online just a little bit longer. Hence Fukushima.

Re:Fukushima was older than Chernobyl

[b0s0z0ku]

Even so -- it melted down. It didn't catch fire and burn for weeks like Chernobyl, because GE designers weren't insane enough to put graphite in close proximity to superheated steam. C + H2O -> H2 + CO

Chernobyl was actually an older class of reactor, even though it wasn't physically older than Fukushima. Based on 1940s plutonium production reactors (and likely, a secondary design consideration was production of plutonium from natural uranium), not really a civilian design.

The Chernobyl design has a few advantages like ability to be refueled while in use (each fuel element had its own steam/water tube that could be isolated) and ability to run on unenriched uranium. But those were outweighed by the disadvantages of the basic design, lack of containment, and poor execution (control rods that increased power when first inserted due to poor design!).

Interestingly, reactors with the same design as the failed Chernobyl plant are still running in Russia proper, though the plants in the former republics and satellite countries have been shut down.

Re:Fukushima was older than Chernobyl

[b0s0z0ku]

The design wasn't terrible -- placing it and its backup generators in a tsunami zone was the terrible part.

Re:Fukushima was older than Chernobyl

[boudie2]

The following 23 U.S. plants have GE boiling-water reactors (GE models 2, 3 or 4) with the same Mark I containment design used at Fukushima, according to the NRC online database:
Browns Ferry 1, Athens, Ala., operating license since 1973, reactor type GE 4
Browns Ferry 2, Athens, Ala., 1974, GE 4
Browns Ferry 3, Athens, Ala., 1976, GE 4
Brunswick 1, Southport, N.C, 1976, GE 4.
Brunswick 2, Southport, N.C., 1974, GE 4.
Cooper, Brownville, Neb., 1974, GE 4.
Dresden 2, Morris, Ill., 1970, GE 3.
Dresden 3, Morris, Ill., 1971, GE 3.
Duane Arnold, Palo, Iowa, 1974, GE 4.
Fermi 2, Monroe, Mich., 1985, GE 4.
FitzPatrick, Scriba, N.Y., 1974, GE 4.
Hatch 1, Baxley, Ga., 1974, GE 4.
Hatch 2, Baxley, Ga., 1978, GE 4.
Hope Creek, Hancock's Bridge, N.J. 1986, GE 4
. Monticello, Monticello, Minn., 1970, GE 3.
Nine Mile Point 1, Scriba, N.Y., 1969, GE 2.
Oyster Creek, Forked River, N.J., 1969, GE 2.
Peach Bottom 2, Delta, Pa., 1973, GE 4.
Peach Bottom 3, Delta, Pa., 1974, GE 4.
Pilgrim, Plymouth, Mass., 1972, GE 3.
Quad Cities 1, Cordova, Ill., 1972, GE 3.
Quad Cities 2, Moline, Ill., 1972, GE 3.
Vermont Yankee, Vernon, Vt., 1972, GE 4.
This was from five years ago. Didn't check to see how many ar still operational but they're definitely old.

Re:Fukushima was older than Chernobyl

[Solandri]

The nuclear parts of the plant itself survived both the earthquake and tsunami just fine even though both events were well beyond the plant's design specifications.

The failure was loss of power to run the plant's cooling systems. Basically, the tsunami swamped the backup power generators and contaminated the diesel fuel reserves for the generators. The destruction of the surrounding roads prevented new generators and fuel from being brought in in a timely manner. And when they eventually did arrive, workers discovered the power couplings for the trucks were different from the ones the plant used, and they had to gerry-rig a connector. All of this took critical time which could've mitigated the severity of the accident. This wasn't an explosion like Chernobyl, it was a gradual event as the cooling water slowly evaporated allowing the fuel rods to melt.

A single diesel generator situated on higher ground with an independent fuel source could've prevented the entire accident. Instead, in stereotypical Japanese fashion, they placed all the generators in a neat row right next to each other in the basement, where the tsunami swamped all of them simultaneously. See, the thing about redundant backup systems (e.g. multiple generators in case some do not function) is that they have to be different to be redundant. If they're the same model, in the same location, using the same fuel source, then any single event which affects one generator will affect all the generators, defeating their redundancy. In fact the two newer reactors at Fukushima on higher ground were just fine because their generators and fuel supply worked as intended. They just didn't have a really long extension cord to reach from those generators to the problem reactors. Basically the failure at Fukushima was the same as when you store your backup drive next to your computer (although the consequences were much more severe). If your house burns down or you're burglarized, both your computer's main drive and your backup drive will be lost. Because you're storing both in the same location, the redundancy of a second copy is defeated by any event which affects that entire location.

Fukushima wasn't a failure of nuclear power. It was a failure of backup (non)redundancy which had nuclear consequences. Basically, because of unwarranted paranoia about nuclear power, everyone concentrated on going over the nuclear parts of the plant with a fine-toothed comb to make sure it was safe. As a result, the non-nuclear backup systems didn't get enough scrutiny, and that's what failed.

It's like airliner safety. Air travel is already far safer than other modes of transport. But because any airplane crash gets disproportionate news coverage, we spend billions of dollars trying to reduce the couple hundred airliner deaths per year even further. Meanwhile the tens of thousands of people dying each year in car accidents gets very little attention. Even including the estimated future cancer deaths from Chernobyl and Fukushima, nuclear power is still the safest power source we've invented (yes, safer than wind and solar based on both on deaths and lost man-days per unit of electricity generated).

Re:Fukushima was older than Chernobyl

[AmiMoJo]

The nuclear parts of the plant itself survived both the earthquake and tsunami just fine even though both events were well beyond the plant's design specifications.

That is incorrect. The plumbing for the cooling system was damaged by the earthquake. The tsunami damage made it impossible to check it in the aftermath, and the fault went unnoticed until it was too late.

That fault, specifically a key valve stuck in the wrong position, meant that the water that was pumped in to cool the reactors from fire engines was diverted to storage tanks. If it had reached the reactors then the explosions and meltdowns might have been avoided.

Fukushima wasn't a failure of nuclear power. It was a failure of backup (non)redundancy which had nuclear consequences.

To two are inseparable and for all intents and purposes one and the same.

But because any airplane crash gets disproportionate news coverage, we spend billions of dollars trying to reduce the couple hundred airliner deaths per year even further.

Is it that, or is it because the potential consequences of a disaster, like an aircraft going down over a city, are very serious? Also, the cost is relatively small compared to the profitability of running an airline. The main issues they have are fuel/pollution, noise and airport capacity. Safety costs come pretty far down the list.

Re:Fukushima was older than Chernobyl

[ChumpusRex2003]

The BWR 1 containment is a small containment. The small volume has the advantage of smaller diameters, hence supposedly the hoop stress should be smaller under hydrostatic load, making it relatively material efficient and easy to build. However, this was a very early design, and when the Mk3 containment was being designed, more robust analytic techniques revealed some significant concerns in the overall containment strength. In the US, the BWR operators formed a consortium to investigate and mitigate these problems, which they subsequently incorporated into their plants. In turn, this led to a number of lawsuits against GE as the cost of the upgrades were substantial.

Additionally, the small containment volume and small volume of in-containment water to act as thermal mass gives very poor performance against prolonged, simultaneous failure of containment cooling, and failure of reactor cooling, resulting in heat being dumped into containment. Prolonged total electrical failure was not anticipated at design time, and led to exactly this situation at all 3 fukushima plants. This led to rapid rupture of the containments once reactor cooling was lost. The latest designs of reactor in construction at present have containment volumes approaching 10x that of the BWR1 containment, as a result, pressure rises in accidents would be substantially lower and slower.

This risk was recognised by the manufacturer and the NRC (in their document NUREG-1150), and in 1987, the NRC published a circular to all BWR plants in the US, giving instructions to plant operators, that if reactor cooling is threatened, the plant operators should initiate containment venting as a matter of the highest priority; this would result in a controlled filtered release, but prevent containment rupture and long-term uncontrolled release.

In Japan, this risk was not acted upon. Whether it was communicated by the manufacturer to the government is not public. However, the TEPCO management had a policy where reactor operators were not authorized to initiate containment venting on their own, and required direct authority from senior management. Due to difficulties in communication, it took hours before the request was acted upon. At that point, rather than authorize venting, senior management decided to refer the matter to the government. Logs from the plants show that in all 3 cases, containment pressure dropped substantially before venting was finally authorized, indicating that the containments had ruptured during the delay for authorization.

Re:Fukushima was older than Chernobyl

[MrKaos]

Fukushima wasn't a failure of nuclear power. It was a failure of backup (non)redundancy which had nuclear consequences. Basically, because of unwarranted paranoia about nuclear power, everyone concentrated on going over the nuclear parts of the plant with a fine-toothed comb to make sure it was safe. As a result, the non-nuclear backup systems didn't get enough scrutiny, and that's what failed.

If you read The Official Report you will find that it was a belief system that nuclear power was a safe high tech energy source that appropriate upgrades weren't performed to the installation due to collusion between the Operator (TEPCO) and the regulator (NISA and NSA).

This shows the dangers of dogmatic skepticism, social proof and imposing a idealistic belief system onto the nuclear industry.

The Fukushima accident shows that the nuclear industry learned nothing from the Chernobyl accident, which is also a conclusion made by the report.

they'll keep it

[bugs2squash]

rename the plant as an experimental facility for radiation testing electro-mechanical systems. Like a wind tunnel but for radiation exposure

Re:they'll keep it

[AmiMoJo]

The idea was to make it possible for the residents of nearby towns to go back. Aside from anything else that is the cheaper option; if people can't go back then they will have to be compensated for everything. Property, businesses, jobs, farms...

Until the plant is safe that can't happen. There is also the decontamination, which has been going pretty badly. But since legal decisions are making it look like full compensation is the only option anyway you could be right, it might just become a write off. I'm not so sure though, I think national pride will require it to be cleaned up.

Re:they'll keep it

[tlambert]

It would be fun to be able to design these bots, though that is not a task my company does. Still, I wonder if we can't go ultra simple? What about something like a bot based only on hydraulic lines, with a fiber optic camera? Can you pass a video image with pure fiber and no electronics? I'm assuming the hydraulic fluid could be controlled by a pneumatic valves. By using air to control movement, you don't need a return line for it. That leaves you with a fiber optic bundle, a send and return hydraulic line, and some smaller bundle of low pressure air lines.

It has been discussed.

The major issue is that the amorphous microscopic structures are particularly prone to radiation induced discoloration of the fiber optic lines. This is worse for the transparent and translucent thermoplastic copolymers, such as methylmethacrylate or polycarbonate.

You'd be replacing the optical fiber fairly frequently, particularly if it were a modern plastic, rather than true glass, although glass will have similar issues.

You end up with coloring in both the visible light regions, and in the IR and UV bands.

This is commonly known as "browning".

While technically, you could throw a laser through the fiber to heat and/or otherwise cause fading.

However, it's going to happen in and around 10^10 Rad.

You can read the original paper by W.H. Cropper here; it was published in 1962:

http://onlinelibrary.wiley.com...

[Note: fees may be involved, if you access this through the Wiley site]

Info...

[XSportSeeker]

I'll just repost my comment from Gizmodo here, some info to kill some potential myths.

It’s bad, and it’ll probably take a long time to be solved... ultimately getting to some point similar to Chernobyl. Not in the same scale I mean, but like years from now they’ll just encase the whole thing in concrete and abandon it there because there’s not much else to do.

Let me tell something about this for people that might be reading and getting a wrong picture out of it, because I also did and just learned recently about some stuff. People should know that for the vast majority of Fukushima prefecture, life remains going like normal. The area affected that people had to evacuate was a radius of around 20 to 30km (12 to 18 miles), which is of course still a lot, but just a small fraction of Fukushima as a whole, which has almost 750 square kms (288 square miles).

It’s nothing to laugh about, but I think some people imagine something like the entire prefecture, or half of Japan being a radiation infested zone or something. Fukushima is the 20th out of 47 prefectures in terms of population, 3rd in area, the capital city wasn’t affected.

I was watching a channel that made a tour around major onsen cities in Fukushima, awesome stuff. Radiation wasn’t a concern, even when they went to a coastal city about an hour away from the power plant.

Again, it’s not to diminish how serious the disaster is, but the thing is, we get a whole lot of reports talking only about the disaster zone, so much that it seems that it’s a huge area that is unlivable. It’s not.

The citing of the plant was certainly negligent

[dfenstrate]

Fukushima's site was dug down to make it easier to build. Just up the coast, closer to the epicenter, Onagawa was built higher above the water line, and they even included a basin to maintain an ocean water supply to the safety related pumps for the duration of a tsunami. They escaped the Earthquake and Tsunami largely undamaged. In fact, Onagawa actually served as shelter after the Tsunami.

Re:droids with even higher radiation tolerances

[93 Escort Wagon]

As long as there’s a smelter nearby, so if necessary we can trick the robots into falling into big vats of molten metal, we’ll be fine.

Warranty Period on Nuclear Reactors?

[LeftCoastThinker]

The two questions I have is why was Fukushima still active after 30 plus years? What exactly is the warranty period for nuclear power plants.
  I would love to get a 30 year warranty on my car or phone. I see they are trying to sue GE... Who issued permits in Japan for this plant? Typically responsibility shifts to the operator after power plants are completed and functioning well since regardless of design or workmanship you can easily destroy a power plant through incompetence or insufficient maintenance.

It is also interesting that the reactor survived the quake it'self but was essentially destroyed by the tsunami.

There is this concept in liability law called Act of God. The Japan Tsunami qualifies if anything ever did. That event killed 15,894 people in a first world country, and as far as I am aware is the highest death toll event in a first world country in at least 70 years outside of war. The Tsunami wave reached a peak height of 133 feet. That is Biblical level apocalyptic disaster right there.

Re:Warranty Period on Nuclear Reactors?

[johannesg]

If your car or phone was built to the same standards, and had proper maintenance applied throughout its lifetime, it would last a lot longer as well. Of course you would be using a 30-year old car or phone, something you would probably consider to be completely unacceptable: the car uses far too much fuel and doesn't have any modern safety features, and the phone doesn't do any of the things you'd want a phone to do. The same is true for nuclear plants: we have much safer designs now.

Unfortunately we cannot build them, because of the great success of the anti-nuclear lobby.

It's a bit of a shame really. If we had continued building nuclear plants we might even have avoided the whole climate change discussion - or we might have been worried about global cooling, and discussing how much CO2 we need to release into the atmosphere to keep the temperature comfortable. But hey, at least the environmentalists won that round...