I've never seen any of these elements
before and so it's really good because I
now feel that I know them a little bit
better I mean you never really know a
chemical till you've tried doing
reactions yourself so it's like meeting
somebody very quickly it's a party
rather than having dinner with them but
still it is a start I know more about
chemistry than I did at breakfast this
morning
okay we're here in the central
laboratory and I'm gonna show you some
neptunium samples
this is neptunium in solution it's been
dissolved and it's in nitric acid at the
moment and what we've got here a three
different oxidation states at neptunium
well down at the bottom of a periodic
table things are very different there's
all sorts of phenomena which are really
very unusual just to do with the that
the sheer size of these elements how the
electrons behave when I hear of nuclear
fuel and nuclear power plants and things
are there
I've heard of uranium and I've heard of
plutonium but you don't hear people talk
about Neptunian what's Neptunian got to
do with the nuclear process or where
does that even come from
okay so Neptune is one of the byproducts
of radiating a nuclear fuel
it's one of the actinides that's
produced and we need to control it
within the prx process to make sure it
goes to the right place and goes to the
correct waste stream it has to be
separated from the other elements when
you're purifying the waste from nuclear
reactors and it has a minor use in that
you can use it to make the isotope of
plutonium
plutonium-238 which is used in batteries
but that's plutonium and neptunium so of
all the elements in the periodic table I
understand it has the largest liquid
range by which I mean from going from a
liquid phase to a gas phase you have to
put in an extra three thousand three
hundred and sixty three degrees C
strictly speaking it's Kelvin but degree
C is essentially the same as Kelvin when
we dissolve the irradiated fuel the
neptunium goes into solution and it can
exist as a neptunium phone at 25 on that
to neum six like many other metals
Neptunian has a number of these
so-called oxidation states in this case
neptunium for neptune m5 and neptunium
six and what these are are atoms of
Neptunian which differ with a number of
electrons they've lost so they can
switch so neptunium five can lose an
electron and go to neptunium six or it
can gain an electron to go to neptunium
four in fact Neptunian five in solution
is not very stable and if you get the
nitric acid concentration not correct
half of it goes the Neptunian six and
half of it goes to neptunium for much of
the skill in this area of chemistry is
manipulating the strength of the nitric
acid to get the right oxidation you want
at the right time and they have bottles
over here of different strengths of
nitric acid which they can drip into the
solution at the right time so when we're
doing research on advanced reprocessing
we'd like to send the neptunium all in
one direction which means control in
these oxidation states we're working on
a floatie actually to convert all of the
neptunium to neptunium six and keep it
there there's a chemical reagent within
nitric acid that is produced through
radiation chemistry called nitrous acid
and having that in the correct amount
also helps stabilize the Neptunian five
internet2 Neum six it's not even a
dramatic chemical reaction it's just
tweaking a concentration there are a lot
of competing chemical reactions going on
they all change at different rates with
temperature so it's finding the balance
where you can derive the equilibrium tor
towards neptunium shakes so neptunium
comes straight after uranium in the
periodic table and it's just before
plutonium and it's not a coincidence
that it's called neptunium because if
you rhenium of course is named after
Uranus plutonium is named after Pluto
and if you think about the order of the
planets
although Pluto now is into planet I
understand Neptune is right there in the
middle people don't use the name
neptunium very often because they don't
talk about the chemistry of the that
elements very often either actually
there's another thing about neptunium
which is that it almost could not have
been neptunium because germanium was
nearly called neptunium of course you
can only have an element named once
so if germanium had been neptunium then
that union would be something else all
right you ready I'm gonna ask you a
question you weren't expecting what do
you know about the planet Neptune I know
it's a long way from Earth yeah I always
think it's the one with a green tinge to
it but I'm not sure if that's right
because they do they become a bit bluer
oh yes I always think of Pluto as being
blue yes I like rocky but Uranus is kind
of green green that's not Neptune's the
bluey one okay yeah