Melted nuclear fuel seen inside second Fukushima reactor

January 19, 2018 by Mari Yamaguchi
Melted nuclear fuel seen inside second Fukushima reactor
A photo taken by a robotic probe provided by the International Research Institute for Nuclear Decommissioning, Friday, Jan. 19, 2018, shows a part of what is believed to be the handle of the fuel rods container and melted fuel in small lumps scattered on a structure below the Fukushima reactor core. The operator of the crippled Fukushima nuclear plant says a long telescopic pipe carrying a camera has captured images of some melted fuel inside one of the three reactors, a crucial information for the decades-long cleanup. (International Research Institute for Nuclear Decommissioning via AP)

The operator of Japan's crippled Fukushima nuclear plant said Friday that a long telescopic probe successfully captured images of what is most likely melted fuel inside one of its three damaged reactors, providing limited but crucial information for its cleanup.

Tokyo Electric Power Co. said the fishing rod-like device carrying a camera went deep into the plant's Unit 2 primary containment vessel. The images indicated that at least part of the fuel had breached the core, falling to the vessel's floor, TEPCO spokesman Takahiro Kimoto said.

"There is so much that we still haven't seen," Kimoto told reporters. "But we were able to obtain important information that we need in order to determine the right method for removing the melted fuel debris."

A massive earthquake and tsunami in 2011 caused three reactors at the Fukushima plant to melt. The plant's decommissioning is expected to take decades.

Melted fuel has previously only been documented inside Unit 3, where an underwater probe captured images of large amounts of melted fuel debris that looked like molten lava mixed with broken parts of equipment and structures on the concrete floor.

During Friday's investigation, the device—developed by Toshiba Corp. and the International Research Institute for Decommissioning, a government-funded organization of nuclear companies—found deposits in the shape of pebbles, clay and other forms, Kimoto said.

Melted nuclear fuel seen inside second Fukushima reactor
A photo taken by a robotic probe provided by the International Research Institute for Nuclear Decommissioning, Friday, Jan. 19, 2018, shows part of a grated platform that broke and fell from a structure below the core of Unit 2 reactor's primary containment vessel coated with what could be melted fuel or structure inside the Fukushima nuclear plant. The operator of the crippled Fukushima nuclear plant says a long telescopic pipe carrying a camera has captured images of some melted fuel inside one of the three reactors, a crucial information for the decades-long cleanup. (International Research Institute for Nuclear Decommissioning via AP)

Determining the location of the melted fuel is crucial in planning for its removal, the hardest process in the plant's decommissioning.

The government and TEPCO plan to determine the methods and start removing melted fuel from one of the three reactors in 2021. But experts say a lack of data is delaying the development of the precise type of technology and robots.

The images from Friday's probe show was what is believed to be a stainless steel handle of a case containing bundles of fuel rods sitting on a pile of pebble-shaped and clayish substances, in a sign the rods melted and breached the bottom of the core. The deposits seemed to be scattered in a wide area around the pedestal, the main structure that sits underneath the core.

Experts say they believe part of the fuel still remains inside the core of the Unit 2 reactor, while almost all of the fuel rods in Unit 1 and 3 melted and fell to the bottom of the primary containment chambers.

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gkam
1.4 / 5 (7) Jan 19, 2018
More benefits of nuclear power.

This was a Faustian Bargain in the first place.
WillieWard
3.7 / 5 (6) Jan 20, 2018
Faustian Bargain
Thanks to fearmongers, Japan and Germany are burning a lot of coal and other fossil fuels to keep lights on when wind isn't blowing or sun isn't shining or during prolonged droughts, and which air pollution respects no border and kills thousands of people every day, millions each year, while no one has died from radiation exposure at Fukushima.
Meanwhile, so-called renewables:
"The EU's bioenergy policy isn't just damaging the climate and forests, it's killing people" - Jan 8, 2018
40,000 deaths
130,000 bronchitis
20,000 respiratory & cardiac
1m asthma days for children aged 5-19
43 million restricted activity days
10 million working days lost
https://www.eurac...g-people
Carbon-free nuclear power is the safest and the most ecologically friendly per unit of energy produced even including the worst-case scenarios, a success in decarbonization.
gkam
1 / 5 (7) Jan 20, 2018
The Navy is having trouble finding places for its nuclear waste. Can the nuke-lovers take it for now?
gkam
1 / 5 (6) Jan 20, 2018
We are shutting down our last two reactor in California. Then, we have to get the stored waste out of the area, which is subject to earthquakes.

But the real path to a modern system is for all of us to be involved. It may be another month before our home batteries are installed here, giving us the ability to be independent. The PV system is sufficient for both house and horsepower, and the advantages of the EVs make them valuable in times of scarce resources.
Tessellatedtessellations
not rated yet Jan 20, 2018
Two things I don't understand about this type of nuclear power plant:

1. Why isn't there a backup steam powered coolant pump? When the electric went out and the reactor began overheating, the heat could have been used to cool the reactor, so why not?

2. Why isn't the reactor floor made to spread out and isolate melted fuel so that the reaction would quickly cease? Just pulling this out of my backside, but perhaps a tungsten jacket full of wells with lead inside inside the casing. As the wells filled, the molten fuel would spread out and fall into surrounding empty wells. The shielding between wells would quench the chain reaction. A heat sink on the back in a vented vat of water might keep the lead from boiling. OTOH, tungsten is pretty dense so maybe it would shield well on its own.

And I just thought of a 3rd. What about a way to introduce tons of lead shot (bb's) into the reactor. Presumably the molten stuff would alloy with it and stop the reaction.
gkam
1 / 5 (4) Jan 20, 2018
Tessel, what you are describing is a device already being used, called a "fuel spreader". I guess we are supposed to assume that makes meltdowns okay.

Or maybe safe, . . like a manure spreader, or something.
gkam
1 / 5 (3) Jan 20, 2018
Oops, I think the term is "core spreader".
WillieWard
2.3 / 5 (3) Jan 20, 2018
We are shutting down our last two reactor in California.
There is no correlation between earthquakes and nuclear fatalities: Fukushima zero deaths from radiation exposure.
Even so, the Eco-nuts/greentards are celebrating the replacement of a perfectly safe source of carbon-free energy by intermittent renewables(bird-choppers/landscape-destroyers) backed up by natural gas(methane/fracking) to keep lights on when wind isn't blowing or sun isn't shining or during prolonged droughts
gkam
1 / 5 (4) Jan 20, 2018
The focus here is on the dangers and costs of the nuclear nightmare, not the spread of much more benign and renewable sources.
WillieWard
1 / 5 (2) Jan 20, 2018
It may be another month before our home batteries are installed here, giving us the ability to be independent. The PV system is sufficient for both house and horsepower, and the advantages of the EVs make them valuable in times of scarce resources.
Are your batteries manufactured/transported by sunshine&breeze-powered machines?
"Those that believe 100% RE is possible, should try it at home: disconnect from the grid and buy enough panels and batteries to carry them through the dead of winter. Next up: don't buy anything that has fossil fuel input, including food."

gkam
2.3 / 5 (3) Jan 23, 2018
Meanwhile, prices for wind power are in a freefall:

https://www.utili.../515188/

"Getting to 'head-spinning' low prices for U.S. offshore wind"

"The just-locked-in price for two projects yet to be built in Maryland has come down drastically, to $0.132/kWh. But even that is nowhere near the high end of the levelized cost for energy reported by Lazard for onshore wind, at $0.06/kWh, or for natural gas, at $0.078/kWh."

Less than one cent/kWh??

What is the cost of nuclear power?

gkam
2 / 5 (4) Jan 23, 2018
Well, gosh, Willie, I am on my way to doing that with electricity. Our household batteries are already ordered. When they finally shut down those dangerous nukes at Devil's Canyon we will be safer.

Meanwhile, you stop using electricity generated by renewables.

And, here is the source of the numbers I posted above:
https://www.lazar...-110.pdf
gkam
2.3 / 5 (3) Jan 23, 2018
"Are your batteries manufactured/transported by sunshine&breeze-powered machines?"

Partially. Poco a poco, Willie.
WillieWard
1 / 5 (2) Jan 24, 2018
Less than one cent/kWh??
Wind and solar worth nothing, useless placebos at night or on cloudy/snowy/not-windy days; without cheap natural gas(methane), people freeze in the dark.
Partially. Poco a poco
It would be funny a grid 100% powered by renewables(in a location of limited hydropower), so it would be possible to realize the real costs of wind and solar and energy storage.
"If RE + storage can't provide reliable power in a lo energy usage, hi RE potential, ideal pumped hydro location, it can't work anywhere"
"If Germany can't hit its own climate goals to help the world, can anybody else?"
https://qz.com/11...ns-next/
Carbon-free nuclear-powered countries/states are showing the way to fight Climate Change:
https://www.elect...map.org/
gkam
1 / 5 (2) Jan 24, 2018
"It would be funny a grid 100% powered by renewables(in a location of limited hydropower), so it would be possible to realize the real costs of wind and solar and energy storage."

Willie, we already have it, and it costs three cents/kWh for wind plus storage and four cents/kWh for solar plus storage. I posted the announcements in these fora.

Meanwhile, if nuclear Vogtle is not cancelled it will cost over 15 cents/kWh. Why would you now want your nuclear Faustian Bargain? Are you ready to store the intensely-radioactive nuclear waste?
WillieWard
1 / 5 (1) Jan 24, 2018
Faustian Bargain
"Nations with more renewables have more expensive electricity"
http://joannenova...tricity/
https://pbs.twimg...glKk.jpg
"Wind/Solar Expansion Will Require Perpetual Subsidies"
http://www.theene...ubsidies
https://pbs.twimg...7ZIb.jpg
Are you ready to store the intensely-radioactive nuclear waste?
Bury it in my backyard. It's safer than arsenide and other chemical carcinogens present in solar panels that never lose their toxicity with time.
https://pbs.twimg...XC-4.jpg
https://pbs.twimg...NTAV.jpg
https://pbs.twimg...jmtY.jpg
https://pbs.twimg...zrxW.jpg
https://pbs.twimg...N5us.jpg
antialias_physorg
5 / 5 (1) Jan 24, 2018
Why isn't there a backup steam powered coolant pump?

By the time water in the cooling cycle turns to steam you're already screwed (because a gas/liquid mixture is a lot less efficient at getting heat off of the fuel rods)

Why isn't the reactor floor made to spread out and isolate melted fuel so that the reaction would quickly cease?

It is. However this stuff doesn't melt out in super liquid form but more of a viscous glob. That doesn't really spread/break very well.

What about a way to introduce tons of lead shot (bb's) into the reactor.

Containment vessels are closed. You can't really inject stuff. There's the moderator rods you can push in, but when the heat spikes these deform (and are prone to getting (stuck).
691Boat
5 / 5 (1) Jan 24, 2018
Why isn't there a backup steam powered coolant pump?


Like AAP said, steam is typically no bueno in a core. also, creating seals that hold in superheated steam without leaking after large periods of inactivity is pretty much impossible, especially in a high flux environment like a reactor.

And I just thought of a 3rd. What about a way to introduce tons of lead shot (bb's) into the reactor. Presumably the molten stuff would alloy with it and stop the reaction.


Some reactor designs have an emergency Boron injection system to help quench the fission process if control rods jam or something.

But, simply quenching the fission process is just step one. Waste heat removal from daughter decay is what ultimately caused the meltdown, since immediate daughter decay heat is between 2 and 6% of previous reactor power. The emergency backup for providing immediate cooling had failed, because they didn't plan for a Tsunami so massive.
Stevepidge
1 / 5 (3) Jan 24, 2018
Faustian Bargain
Thanks to fearmongers, Japan and Germany are burning a lot of coal and other fossil fuels to keep lights on when wind isn't blowing or sun isn't shining or during prolonged droughts, and which air pollution respects no border and kills thousands of people every day, millions each year, while no one has died from radiation exposure at Fukushima.



Fossil fuels..... There is ZERO real proof that oil is a product of decayed organic matter. ZERO.
MR166
1 / 5 (2) Jan 24, 2018
Steve a few years ago I would have thought that you were crazy. But with the ethane and methane lakes on Saturn's moon Titan the whole fossil theory needs to be questioned.
MR166
1 / 5 (1) Jan 24, 2018
Let's face it all of the ingredients are in carbonated water. Just add some high temperatures from the core of the earth and the Hydrogen and Carbon will split from the Oxygen. By the time things cool down the oxygen might not be available for the recombination and we get hydrocarbons. We can do this sort of thing in the lab, why not in nature?

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