
422 Nuclear Forensic Analysis
grains showed a wide distribution of sizes, spanning the interval from 30 to 550nm,
w
ith
a
me
an
d
iameter
o
f
~
160nm
(
Figure
2
0.6).
T
he
a
bundance
o
f
v
ery
s
mall
g
rains,
w
ith
d
iameters
<
300nm,
p
rovided
a
n
i
mportant
c
lue
t
o
t
he
m
anufacturing
p
rocess
us
ed
t
o
m
ake
t
he
H
EU,
a
s
s
uch
s
mall
s
izes
ca
nnot
b
e
g
enerated
i
n
c
ommercially
a
vailable mechanical grinding and milling operations.
The
major portion of the sample, ~2 g, was dissolved in nitric acid for radio-
chemical
a
nalyses.
T
he
c
oncentrations
o
f
3
5
i
ndividual
r
adionuclides,
s
panning
1
5
o
rders
o
f
m
agnitude
i
n
c
hemical
c
oncentration,
w
ere
d
etermined
b
y
α- a
nd
γ-
spe