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in the episode today we're going inside
the nuclear reactor and not just any
reactor but the reactor that is used to
make the rare isotopes of elements like
berkelium californium the ones that are
so important for synthesizing the
super-heavy elements so this is an old
reactor and the reason why this reactor
is here is because of a gentleman named
Glenn Seaborg he had a lot of work at
Berkeley labs and he had a vision of
practicing that work on these heavy
elements but he didn't have a great
supply of it and we can look forward
with that hope that nuclear energy will
become the servant of all men everywhere
he pushed the Atomic Energy Commission
through the 50s pushed and pushed and
pushed and finally of course he won the
Nobel Prize in Chemistry 1951 and he did
a little bit of credibility and and he
finally made some progress in the late
50s 1958 and the Atomic Energy
Commission said yeah we want to do this
we want to build a reactor to produce
heavy elements for you to do your
chemistry and so the Commission looked
around the country at the time and at
that time in the late 50s there was a
lot happening with nuclear reactors a
lot of drawings a lot of designs being
put on paper particularly here in
Oakridge America's atomic city at Oak
Ridge Tennessee has been open to the
public and even the opening was by
atomic energy watch that tape
Oh Craigs had the only school that was
specifically designed for reactor
engineering it was called the Oakridge
reactor engineering school and this
gentleman who's on the wall dick chevre
ttan has a plaque up here he was a
student in that school at that time and
he'd come up with a concept and the
Commissioner of the Atomic Energy
Commission saw this concept and said
yeah I think this is the one Len T
Seaborg needed a nuclear reactor with a
high Neutron flux so that he could get
the elements to study up till then he
had gone to the sites where there had
been nuclear tests and looked among the
rubble for traces of these elements and
obviously this is not very
environmentally friendly and there's a
limit to the number of nuclear tests
that can be done and people are not very
interested in doing a test just to make
some exotic elements in 1960 they broke
ground on this site and then they put
the reactor building in and put the
reactor in and they were up and running
by 1965 so for the first 20 years of
operation we produced these heavy
isotopes small quantities but we
produced it very regularly we operated
very regularly and we operated often
meaning the total number of days we
operated over the year was very very
large 75 percent now we operate much
much less about 50 percent of the year
we actually operate and our mission has
shifted over the decades now our mission
is neutron scattering condensed matter
physics but we still have an isotope
component we still make isotopes so we
got a big window this is our Bay our
reactor is actually to the right side of
the pool
the yellow bridge has a dam underneath
and that well that doesn't have a dam
today I can see the dam is out the dam
has actually moved to the left we're
currently shut down for an outage and
but the reactor is in the pool on the
right kind of you see the stairway going
down that stairway goes down to a
platform basically a grating so we can
lower that when we have the dam in place
we can lower that pool
we can actually walk down there and
perform maintenance and repairs in the
pool is the reactor vessel we're a
pressurized reactor so we have a very
sizeable pressure vessel and then the
reactor core is actually inside of that
vessel the vessel itself is it's eight
feet across so what two and a half
meters but the core inside of the
reactor is where all the action happens
this reactor is designed to produce
neutrons not to produce power it's not
trying to make electricity like say
Chernobyl reactor was so it's small and
it produces the neutrons at a very high
rate and then it burns out quite quickly
each reactor core only lasts at its
proper operating power about 25 days
less than a month the reason we
pressurize it is to increase the boiling
point of water so that we can cool
without boiling our reactor because we
produce an enormous amount of heat along
with an enormous amount of neutrons
what's the liquid in the pool plain
water just out of the tap water you
purified a slightly demineralized there
are still some minerals in it but we do
demineralize it water is all for cooling
all we're trying to do is remove heat we
produce a huge number of neutrons in
ways that we can explain a million
billion neutrons 10 to the 15th neutrons
every second hit a square centimeter
that's just one square centimeter it's a
huge number of neutrons so the pool
water is separate from the water that's
inside the pressure vessel and the pool
water remains at about 100 degrees
Fahrenheit the water inside the vessel
starts out at about 120 degrees
Fahrenheit as it passes down through our
reactor core it raises about 36 degrees
Fahrenheit exits at about 156 degrees
Fahrenheit way way below boiling this is
good for us power reactors they want to
generate steam but we don't want steam
steam would be bad for us we would like
our water to be liquid it it's blue
because there's so much metal in there
it really isn't blue
and we get that question often but it's
pretty but it's not like there's an
additive so this is a mock-up of our
fuel our fuel is different power reactor
you know uses fuel rods we use fuel
plates but they're arranged in a very
strange arrangement for compared to
other research reactors even our fuel is
met is placed in these plates that are
in here these are curved plates and we
basically have two fuel elements an
outer element and an inner element this
part in here which has rods these are
not fuel rods
these are target rods this area is an
area of very high Neutron flux so this
is the business end of our reactor for
making isotopes when we make californium
252 which you may have learned about
next door or Berkley m249 we make it in
here in the flux trap the main point of
the reactor is to have a tube in the
middle in which you put your samples in
fairly long thin essentially metal test
tubes to be radiated and neutrons are
important because these heavy elements
can be formed by bombarding lighter
elements with neutrons these fuel
elements are mostly aluminum but inside
of these fuel plates is uranium so we
have you we use you 308 which is uranium
oxide and it's sandwiched in between two
aluminum plates so we we basically
protect the uranium but allow it to cool
very effectively by having these very
small channels to force the water
through and that's why we raise
temperature from 120 to 156 it all all
that heat transfer happens through these
plates so the plates themselves are
about 24 inches but the we call the fuel
meet the uranium is really about 20
inches tall so about 20 inches of fuel
meet and and the rest of the aluminum
our fuel actually the uranium comes from
the y-12 national security complex and
we get our uranium for free however
the free part is metal chunks and we
can't use metal chunks in our fuel so we
have to pay to have our uranium
converted to you 308 oxide so y12 does
that they convert it to an oxide and
then our fuel is actually fabricated at
BW XT technologies which is in Lynchburg
Virginia they are the ones that take
that you 308 and they blend it with
aluminum powder and they form these
compacts so basically the you 308 and
the aluminum are blended together they
press it into these compacts these
compacts are then put into this aluminum
picture frame so now you can envision
there's uranium there's aluminum in this
in these middle sections here and this
is just all aluminum and then we
sandwich that with an aluminum plate
then we take that plate and we roll it
out then what they do is they form it
into this shape and this is a unique
shape this shape is called an involute
shape
what makes that shape unique it's the
only geometric shape that you can stack
around a circle and maintain a constant
water gap thickness you can't do that
with a circle you can't do it with
anything else it's it's and this
involute shape so here on this dummy
version I'm looking at these are
representing to feel the uranium phase
like this just like pretty fluted area
here yep right yep both these fluted
areas are where the uranium is that's
where we generate all of our power are
all our Heat all of our neutrons and how
are you making sure that most of the
neutrons go to the center where you want
I assume you want them to go to the
center more than the outside well you
can't really control that however that's
the that's the amazing part of this
unique design that Dixie Burton came up
with is this flux trap he called it a
trap but it's really just a high
concentration there's no such thing as
trap and can't trap a Neutron but you
can create a high density of neutrons
and that's basically what this does
however those neutrons do go outward to
in fact if we look at this mock-up this
gives us a more complete picture of the
of the reactor core
so we have our flux trap that we saw
over there we have our fuel
we have a small region called our
control region and then we have a
reflector region so these are all
annular regions our reflector region
this is necessary for the reactor to
work and so is our control region the
reflector is made of beryllium and
beryllium is a unique material its
unique neutronic Li because when a
neutron hits beryllium on average about
2 and 1/2 new neutrons are made from
that their lower energy than the ones
that came in and hit it but so you get 2
and 1/2 neutrons some of those neutrons
go back into the fuel and cause that
fuel to fission more and you build up
this population of neutrons some of them
can be used for experiments that are out
here in the core in the reflector so you
just let your descent we've got this
great neutral environment the scientists
like what else can we chuck in there to
see what happens
yeah so in fact out here what we
generally make these days is we make
plutonium 238 for NASA
so we start with neptunium 237 and we
irradiate those neptunium target for
three of our operating cycles which is
about 25 days easy so 75 days of a
radiation and we convert about 10% of
that neptunium to 37 to plutonium-238
then we take it to the hot cells next
door that you just visited they extract
that they ship it out to Los Alamos and
eventually it ends up in Radio
thermoelectric generators RTGS
for example like the one that's on Mars
rover Curiosity or the one that's going
to be on Mars 2020 Rover between the
coal and the reflector there are plates
containing the element europium one of
the rare earths europium in this context
is a very efficient absorber of neutrons
so it stops the neutrons from the core
getting to the reflector and the control
plates are in two parts so that you can
move one up and one down and adjust the
size of the gap between them so when
you're ready to go everything is
assembled the reactor is in its case in
water for the cooling and everything is
shielded then remotely you can pull
these control plates apart and the outer
one moves up and the inner one moves
down and we create a window of
communication between the fuel and the
reflector so the neutrons can
communicate and we build up that
population of neutrons and then we
finally go critical then what we'll do
is for the remainder however long it
takes if it takes 23 days 25 days 27
days we pull these plates apart until
they're all the way out and once they're
completely out and we can't maintain 85
megawatts we shut it down but at any
point if you if you shut the window
through the whole thing would go out
what it turns off what's going on in the
center where those where the rugs are so
those targets we do produce other
isotopes we make nickel 63 we make
selenium 75 we make californium 252 and
then we also make some
these other elements the like the
berkeley m249 what are the rods
typically made of or does that depend on
what you're trying to achieve it depends
on what you're trying to achieve but
most of the targets most of the
components in in the reactor and
especially the targets are have a have a
capsule housing made of aluminum so most
targets are made of aluminum and then
they have some material interest inside
in the case of plutonium like I
discussed in neptunium 237 in the case
of californium 252 we start with heavy
curium which might be curium 246 or
curium 248 for selenium 75 we have
selenium 74 targets so we generally want
most most of the processes are to
capture neutrons to get to the next
isotope we are fairly full but we have a
regular routine set of radiations that
we do particularly for isotope
production but we also do a lot of
materials radiations testing in here we
have a lot of materials for material
science in that core it's one of these
it lasts for 25 days when we take it out
we put a brand new one in each one of
these is about 1.8 million US dollars
and it lasts for 25 days so and then
what happens is it refurbed or that goes
in the in the bin
so what happens is so as I said we're in
an outage this is a temporary just a
little cap to cover so we don't drop
things in there but this is our vessel
head this is the part that's about eight
feet in diameter this is the grating you
can see that you can actually walk down
the steps to get to not a lot to see
here because we're not operating usually
when we're operating you can see a blue
glow you get the shrink off radiation
glow so you slide the core in today idea
yes so it's actually quite deep down in
there so we use very long tools attached
to things and the operators roll the
bridge over and then they can lower the
fuel down into the core location it's
that always an exciting day for you guys
like there's everyone come out and watch
and go we're starting a new Under
like just routine now I will say it's
fairly routine now
putting it in taking it out is more
exciting but generally that happens
overnight so not a lot of people come
out overnight but when you take it out
you take out elements that look like you
get the nice Cherenkov glow we don't
have a lot of them right now that are
glowing but and actually we don't really
see many glowing usually we would have
these would be glowing that they've been
out for quite a while we've had a long
outage so they've had time to decay so
these are out ones cooling down these
are old ones cooling down
[Music]
they always stay underwater and they
stay in this center section of the pool
for maybe two or three years and then
eventually they go over to these racks
which are three tiers so we can hold a
lot of elements over here and then
eventually they get shipped to Savannah
River Site where Savannah River Site
will dissolve them and extract out the
good remaining material and recycle that
into a program that supposedly makes
power reactor fuel not very familiar
with their program how do you get to
stuff out that you've just made like you
know all that all those cool isotopes
that everyone's dying to get their hands
on how do you get them out of there of
the core and all those surrounding
little cylinders so that's that is a
challenge and I will say that is what
our operators do with long tools it's
like a laparoscopic surgery to get these
out so it would be nice and you look at
the top of this and you see these plugs
and holes those plugs and holes
initially you think oh those line up
with the holes that are on top of the
reflector but they don't the reflector
is actually only about this diameter
everything we do has to go through this
one hatch so they're working down there
and they're going around things with
these long tools it's arduous it's
difficult but they've they're very
talented at it so it is difficult to get
things out but we do we do it routinely
every cycle and then they literally take
them and they just keep them underwater
they drag them across to the other side
of the pool and then we can we can store
them we can put them in shipping casks
and then we can ship them over to the
hot cells or wherever they're going to
go
these few elements while they're not
producing neutrons or many neutrons they
are still producing a tremendous amount
of gamma radiation so we use these we
have developed a small canister that can
go down into that flux trap area and we
can fill that canister we can stream
water or electricity or whatever we want
into that canister we can do
high-intensity gamma radiation these are
our control plates you can see that I
described the two cylinders okay that
was a little bit of a stretch they are
two cylinders but the inner cylinder is
one contiguous cylinder the outer
cylinder is actually made up of four
plates and you can see one of these
plates here on the windowsill that's an
example of a control plate these are
very difficult to fabricate they take a
tremendous amount of time they're very
expensive remember these have europium
oxide inside as a meat and they take two
years to fabricate a set like this so
when we do shipments we can actually
pack a truck in here and it comes right
over to this area where these gray
squares are and we can use the big crane
and bring the big shipping cask and set
it down
the shipping cask four californium to 52
targets is quite large it's a nine foot
diameter sphere that they've painted
white and call the cue ball it weighs 25
tons so it's not it's not insignificant
and it can get set onto a truck very
exciting when they ship californium and
plutonium targets are shipped in the
same in the same cast I was really
impressed that they're using this
reactor for all sorts of different
experiments not just making the new
elements they also have beam lines
coming out from the reactor generating
beams of neutrons the reactor core is
that way the beam you can see the red
lines designate three beam lines there's
actually a fourth one on the far right
that doesn't get a red line so we have
four beam lines that come down and they
actually get split even further because
we have more than four
experiments out here so these large
tanks are called Sands tanks small-angle
neutron scattering tanks they get
evacuated there's a detector plate a
large 1 meter square detector plate
inside and they can use the beams of
neutrons for what so called neutron
diffraction which will allow you to do
all sorts of interesting experiments the
one that really excited me was that you
can take a diesel engine like for a car
and you can image the fuel being
squirted into the engine block by
shining neutrons through the block of a
running engine and because the fuel
contains hydrogen atoms which absorb
neutrons strongly you can see this jet
of fuel going into names and when it's
running without disturbing any of the
workings of the engine have you seen our
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videos
Walmart is in the middle of South
Australia Woma is actually an Aboriginal
word for a throwing device and that's
how they say appropriate yeah cuz
launching rockets and things yeah the
black stamp so here they're taking all
their supplies Australian servicemen and
scientists paid a big part in the
operation which included the
construction of a tower the tower that
vanished instantly when the atomic
weapon was exploded on it