60 minutes rewind
more than seven years have passed since a monster earthquake and tsunami struck northeast japan
and triggered what became after chernobyl the worst nuclear disaster in history
at the fukushima daiichi nuclear power plant when three of its six reactors melted down
hot fuel turned to molten lava and burned through steel walls and concrete floors to this day no one
knows exactly where inside the reactor buildings the fuel is and it is so deadly no human can
go inside to look for it so the japanese company that owns the crippled plant has turned to robots
there are four-legged robots robots that climb stairs and even robots that can swim into reactors
flooded with water they're equipped with 3d scanners sensors and cameras that map the terrain
measure radiation levels and look for the missing fuel this is part of a massive
cleanup it's expected to cost nearly 200 billion dollars and take decades has anything
like this cleanup in terms of the scope ever happened before no this is a unique situation
here that's never happened in human history it's a challenge that we've never had before
lake barrett is a nuclear engineer and former department of energy official
who oversaw the cleanup of the worst nuclear accident in u.s history three-mile island he was
hired as a senior advisor by tepco the tokyo electric power company that owns the plant
and is in charge of the effort to find the missing fuel he's also advising on the development of new
robots like this six-legged spider robot that engineers are designing to hang from scaffolding
and climb onto equipment he describes them as very advanced working robots that will
actually be the ones with long muscular arms laser cutters and such that will go in and actually
take the molten fuel and put it in an engineered canister and retrieve it should we think of this
as a project like sending someone to the moon it's even a bigger project in my view but there's a
will here to clean this up as there was a will to put a man on the moon and these engineering
tasks can be done successful why not just bury this place why not do what they did at chernobyl
just cover it up bury it and just leave it here
all in you know enclosed number one this is right next to the sea we're 100 yards from the ocean
we have typhoons here in japan this is also a high earthquake zone and there's going to
be future earthquakes so these are unknowns that the japanese and no one wants to deal with
the earthquake that caused the meltdown measured 9.0 the most powerful ever recorded in japan
and triggered a series of tsunami waves that swept away cars houses and entire towns
killing more than 15 000 people at fukushima daiichi the enormous waves washed over the
plant flooding the reactors and knocking out power to the cooling pumps that had kept the
reactor cores from overheating lake barrett took us to a hill overlooking the reactors where the
radiation levels are still relatively high so this is actually right where it all happened the
heart of the disaster right here correct there's reactor number one reactor number two reactor
number three and when the earthquake happened 100 miles away these buildings all shook and these
towers all shook but the design was such that they were they were safe but 45 minutes later
waves were racing in tsunami waves from the earthquake there were seven waves that came in
at 45 feet high and put the station in what we call station blackout they had no power
and the cores got hotter inside and hotter and hotter again until the uranium started to melt
how many tons of radioactive waste was developed here probably 500 to 1000 tons in each building
so how long will it be lethal i will be lethal for thousands of years what we're talking about
really is three meltdowns yes it was truly hell on earth the meltdowns triggered huge explosions
it sent plumes of radioactive debris into the atmosphere
forcing the evacuation of everyone within a 12-mile radius about 160 000 people in all
weeks later tepco officials engaged in so-called diplomacy
allowing townspeople to berate them as they prostrated themselves in apology
thousands of workers were sent to the countryside to decontaminate
everything touched by radiation including digging up dirt and putting it in bags
lots of bags but while much of the evacuation zone has been decontaminated there is still
entire neighborhoods that are like ghost towns silent and lifeless with radiation levels that
remain too high at the plant they're capturing contaminated groundwater about 150 tons a day
and storing it in tanks as far as the eye can see water is always the major challenge
here and it's going to remain a major challenge until the entire cores are removed the closer
workers get to the reactors the more protective gear they have to wear as we discovered we were
zipped into tyvek coveralls and made to wear two pairs of socks and three pairs of gloves
not an inch of skin was exposed the layers of protection include a mask it's a little loose
that often fogged up how we feel and a dosimeter to register the amount of radiation
we'd be exposed to we were ready for battle we went with a team of tepco workers to unit three
one of the reactors that melted down on that march day seven years ago that the japanese call simply
311. lake there you are unit 3. watch it step these are shield plates because there's cesium
in the ground in the years since the accident much of the damage to the building has been repaired
but it's still dangerous to spend a lot of time here we could stay only 15 minutes there's this
number i've been seeing five six six right that's telling you the radiation level that we're in
it's fairly high here that's why we're going to be here a short time how close are you and i
right this minute to the core the melted cores are about 70 feet that way 70 feet from here is the
melted core correct that's right over in here we don't know quite where and other than it fell down
into the floor so if you sent a worker in right now to find it how long would they survive
no one is going to send a worker in there because they'd be overexposed in just a matter of seconds
enter the robots this is the robot research center this is for remote control technology development
in 2016 the japanese government opened this hundred million dollar research center
near the plant where a new generation of robots is being developed by teams of engineers and
scientists from the nation's top universities and tech companies dr kuniaki kawabata is the
center's principal researcher this is the newest robot the j11 so number 11. and what
it's it's an obstacle course yes the operators use the camera image in front of the robot but
it's for so many hours required to train because it looks very easy but it's quite difficult they
also train here in this virtual reality room with 3d data taken inside the reactors by the robots
is projected onto the screen operators using special glasses can go where no humans can
so we're actually walking through a part of a reactor you feel some immersive experience as
if you're in there yes i actually want to duck i mean that's how real it feels to me like here
we're going under this thing i have to duck ah yes the story will continue after this
but even with all the high-tech training and know-how the robots have run into problems
for the early models it was the intense levels of radiation that fried their electronics and cameras
their lifetime was ours we'd hoped it would be days but it was for hours tell us what happened
to the robot named scorpion this is a highly sophisticated and i'd gather everybody thought
this was the answer that was going to be the first robot we're going to put inside the containment
vessel which is where we need the information the most because that's where the core is
this is scorpion whose mission cost an estimated hundred million dollars it was designed to
flatten out and slither through narrow pipes and passageways on its way to the core and like a
scorpion it raises its tail the tail would come up with a camera on top with lights because you
have to have its own lights it's all dark inside there are no regular lights so that was the plan
and we had great expectations and hope for that we all did took a year to prepare and it was hard
work but when scorpion went inside it hit some debris and got stuck after traveling less than
10 feet i can't imagine the frustration limb levels well but you'd learn more from
from failures sometimes than you do from success they had more success with this robot
named little sunfish which was designed to swim inside one of the reactors flooded with water
in preparing for little sunfish's mission engineers spent months
doing test runs inside this enormous simulation tank fine-tuning the propellers cameras
sensors and 65 yards of electric cable all built to withstand intense levels of radiation
they used nuclear reactor number five to help plan the mission it didn't melt down when the
tsunami hit and is nearly identical to the one little sunfish would scout finally last year the
swimming robot made its foray into the heart of the reactor to look for the missing fuel
barrett took us into unit 5 to show us how it maneuvered through the labyrinth of pipes
and debris inside the reactor the little sunfish came down on the edge and it swam underwater
down through this little entryway here underneath the reactor vessel
is this the route that the little sunfish took yes this is the little sunfish swam through this
portal down into this area it went around the side it went down through this grating which was gone
we are standing directly underneath the reactor vessel molten fuel came through here and it
jetted out under very high pressure and then it came out slowly like a lava and a volcano
and it fell down and burned its way through this grating down to the floor this is what little
sunfish saw as technicians guided it through the pipes and hatchways of the flooded interior
it beamed back images revealing clumps of debris fuel rods half destroyed equipment
and murky glimpses of what looks like solidified lava the first signs tepco officials say of the
missing fuel these robotic steps so far have been significant steps but it is only a small step on
a very very long journey this is going to take you said decades with the s how many decades we don't
know for sure the goal here is 40 30 40 years you know i personally they may be to 50 60 but
oh maybe longer well it may be longer but reality is this is a challenge that's never been dealt
with before but every step is a positive step you learn from that and you go forward to another step