americium is really a very radioactive
element so it is handled in this glove
box and I'm not qualified to use such
equipment so mark who works here will
tell us about it so this is a this is a
vial of americium-241
which is one of the isotopes of
americium and this was separated from
some plutonium because one of the
isotopes of plutonium plutonium 241
decays into americium-241 with a
half-life of 14 years it turns out you
can make americium a number of ways it's
generated when nuclear weapons are
detonated it's also found in spent
nuclear waste from nuclear reactors so
for example if you took a turn of
material being used in a nuclear reactor
and took it to one side there'd be about
100 grams in that turn would be Elysium
this is actually ultraviolet visible
spectroscopy cell and it goes into this
holder which has 2 fiber optic
connections to it and what happens is we
pass light from the spectrometer through
these fiber optic cables through the
solution and out the other side and the
spectrometer provides a fingerprint of
what element is in that solution and
that fingerprint is very specific to our
aja
and Marisa is the only trans uranium
element that you're likely to have a
sample of in your house in fact you may
have several samples because americium
is used in very small quantities
nanograms one thousandth of a millionth
of a gram in smoke detectors that we all
have in our houses to prevent as being
burnt to death if there's a fire
they were meant to put it off hi
you forgot this doll I've
actually got Martin polyakov's old smoke
detector you haven't taken away anyone
from his elf we haven't taken the
working one no that wouldn't be safe but
we took one that stopped working this is
the inside of the smoke detector and you
can see here it actually says americium
well I'm Marisa I'm is a strong emitter
of gamma rays and alpha particles and
these are used in the smoke detector
because if you get particles of smoke
those are stuff that makes smoke look
white they intercept the radiation and
stop the radiation getting from the
radioactive source to the detector in
your smoke detector so in fact what's
measuring is a drop in the current going
between the source and the detector and
the alarm goes off and it says that
there's not 0.9 micro Curie's now I
don't know about you but I don't
normally remember what not 0.9 micro Q
is really means it means there's naught
point to 6 micrograms and you might sit
then think what earth does he mean by
that well if you think of a grain of
rice it weighs a hundred thousand times
less than the grain of rice it's got
quite a history to it as well it was
first discovered in 1944 but this was
kept secret for a whole year until it
was eventually allowed out into the
public domain and the reason it was kept
secret is because it was part of the
Manhattan Project when there was all of
a search to generate nuclear weapons so
people didn't want competitor groups to
understand how far ahead they were
compared to the competition so they kept
the discovery of an entire element in
the periodic table secret for a whole
year but then it was leaked out and then
basically they had to tell everybody in
nuclear fuel reprocessing
that the objective is to produce a pure
uranium and a pure plutonium product
stream now here at Sellafield those
materials are put into storage and over
time one of the isotopes of plutonium
plutonium 241 decays into an isotope of
americium americium-241
and so over time americium grows into
these plutonium stocks so it's possible
to separate the americium from the
plutonium by chemical methods when it
was first prepared it was prepared
because people predicted that these
elements ought to be synthesizable just
they didn't exist naturally so of course
this was a challenge to chemists there's
a little bit of interesting story behind
the synthesis of these elements because
they were quite arduous like long winded
piece of plutonium was coated onto some
platinum foil oxidized to plutonium
dioxide put in a cyclotron once this was
over with they would take this foil and
they would dissolve what they wanted
away with concentrated nitric acid and
then they had to precipitate what they
wanted as a hydroxide using an ammonium
reagent and dissolved it a McLaury acid
some curium was removed you then had the
americium and the people who did this
process found it so tedious and so
arduous that they actually referred to
it is pandemonium which is Greek for all
demons or hell what is interesting is
the demolition is an element which may
become more useful in the future it may
be able to replace plutonium in
batteries for spacecraft and so on
so currently plutonium 238 is used but
to be able to generate that within
Europe would require very expensive
infrastructure to be put into place
including
a source of neptunium 237 generation
building a reactor specifically for
converting neptunium into lutonium 238
and it all becomes very expensive the
production of blue 238 stopped in the US
a number of decades ago and they haven't
resumed production to this date so
stocks are running low the European
Space Agency would like to have an
independent supply of these power
sources so they've commissioned a
program of work to look at an
alternative to plutonium 238 and it's
possible that americium-241 could
fulfill this role I'm regime 241 doesn't
produce the same amount of power but it
could be used in smaller applications I
don't like the names of elements that
are named after countries because I feel
chemistry is an international subject
though I suppose that americium although
it's clearly derived from America
doesn't sound terribly like America and
therefore it's not bad as a name and
once something's got a name it's
difficult to change it and everybody
calls it americium so we're stuck with
it like that and rotate it around
nothing much happens oh let me put it
vertical and it stays where it is