la
avy iar iodine decontamination.
Tne icdine is finall; srecinitated as Ast
and
mounted on thin plastic scintillators for counting.
The
126,
128
'
, 130
IT and
IT activities produced in the sample and ccemparator
standards during irradiation are determined by zamma-vray spectrometry from sev-
erai spectra collected over a period of time.
Low-level, beta-gated, muitipie
gamma-coincidence spectrometric techniques (10) are used when required to mea~
.
sur2 very small amounts of activity.
The
i25
oe
.
.
.
I activity 1s aiso measured in the
sampie and comparator standard by gamma-ray spectrometry.
The components in the time-dependent gamma-ray ssectra of samples and the
comparator standard are calculated by a weighted least-squares method (il).
The
- 127
i129,
.
.
‘
(ook
.
amounts of
I and
T in the comparator standard are determined from the
'
amewn
Lo5.
(127
~""L,
L,
129
.
-
I ratios by measurement of the
125
“I.
The
130,
I,
129,
L’
i128. 127
. 126.,127.
.
.
: os
.
ey)
IT and
1/
L ratios are then caiculated for the comparator standard.
74
~
TA
79
.
1
oa
“~
The ‘*’t concent of the sample is determined from either the 1267 ge 148, aceiy.
uty produced
.
in the sample,
129
were concentration,
dure yleld.
and
the
the
125
.
induced
130
.
.
.
.
.
IT activity 1s used to determine
L activity is used to calculate the overaii proce-
Corrections are made for interferences, procedure yieid,
.
.
blanks and sampling Dlanks where applicable.
laboratory
og
127
The results obtained are the
Tt
. 129
.
.
.
129. 127
.
and “““I concentrations per unit amount of sample and the “1,
I ratio.
dine isotopic atom ratios for
the
1
129,127
Lon
-12
I as low as 10 12 nave been measured (2).
Tne overall procedure yield for iodine recovery is about 502.
COMPARATOR STANDARDS
We have used several differenc comparator standards for iodine activation
anaivysis.
Elemental iodine (1,) Standards were prepared oy isotopic dilution
ts
127
.
og
with xnown amounts of natural iodine (*°'I) of mass spectrometricaily analyzed