Man Made Isotopes
.
3.1
PRODUCTION OF NEW ISOTOPES IN DHRUVA
Production
of
Uranium-232
from
Protactinium-231
1g of oxides of zirconium and silica) was loaded in the Dhruva
reactor for irradiation. Based on the earlier trial irradiation results,
the total fluence planned for this irradiation was kept around
0.25 x 1014 n/cm2. After conversion of around 5% 231Pa to 232U,
U-232 isotope is produced in the Thorium fuel cycle along with
the post irradiation chemical separation was carried out by
U-233, generally in the concentration levels of a few hundred
dissolution and solvent extraction. The figure shows the α−
parts of U-232 per million (ppm) of U-233. U-232 is a short-lived
spectrometry of the separated U-232.
isotope (half life ~ 72 years) with hard - emitting daughter
products. Study of U-232 is of interest to U-233 fuel
development.
L. M. Gantayet <[email protected]>
Head, ACD <[email protected]>
.
Pure U-232 is produced by the nuclear reaction 231Pa (n, γ) 232Pa
232
U. 231Pa was obtained as a 10 ppm concentrate in 2002 from
Synthesis
of
Isotopically Pure
236
Pu
Tracer
236
Pu is an ideal tracer
required for the assay of
plutonium in biological
and in environmental
laboratories of nuclear
installations. The p + 237Np
reaction was used for the
synthesis of trace levels of
isotopically pure 236Pu by the
recoil catcher technique. The
surface decontamination of
the catcher foils followed by
radiochemical separation of
plutonium yielded about 200
mBq of tracer grade
Alpha spectrum of U-232 sample
236
Pu
activity. Electrodeposited Neptunium targets (2.0 mg/cm ) were
2
irradiated with proton beam (Ep = 23.5 MeV) at BARC-TIFR
Pelletron Facility, Mumbai. After irradiation, the stack was cooled
the insoluble muck (containing 2 to 3 parts per billion Pa - 231)
of the monazite processing plant.
for 15 days for allowing the complete decay of 236mNp (T1/2=
22.5 h) to
Concentration of Protactinium-231 from 10 to 1000 ppm was
carried out in the laboratory by successive elution ion
chromatography in oxalic acid medium, hydrofluoric acid and
hydrochloric acid media to remove undesirable impurities. The
16
Pa, (~7mg
BARC HIGHLIGHTS
231
Pu as well as
237
237
Np. The activities of
Np were below the detection limits (<
0.1 mBq). About 200 mBq of tracer grade 236Pu activity in 8M
HNO3 was prepared. A typical alpha spectrum of 236Pu source
is given.
batches were prepared for irradiation and production of U-232.
231
Pu. A method based on solvent extraction was
standardised for effective removal of
238,239,240
The first batch of
236
Pa on a carrier of around
Chemical Sciences & Engineering
Man Made Isotopes
24
Na@C60, 34mCl@C60, 69Ge@C60, 71As@C60, 72Se@C60, 75Se@C60,
77
B r @ C 60,
81
R b @ C 60,
83
S r @ C 60,
86
Z r @ C 60.
The yield of endofullerenes obtained was in the range of
10 - 20 % for electropositive metal (24Na@C60 : 15.1, 81Rb@C60
: 13.0,
(
83
Sr@C60 : 15.0,
86
Zr@C60 : 20.5) and 70 - 90 %
Cl@C60 : 71.5, Ge@C60 : 72.9, 71As@C60 : 73.8, 72Se@C60 :
34m
69
82.5, 75Se@C60 : 76.3, 77Br@C60 : 79.3) for others. The yields of
endofullerenes were independent of the energy of recoiled
nuclides (1 - 10 MeV).
.
Alpha spectrum of radiochemically separated Pu-236
V. K . M a n c h a n d a < v k m @ b a r c . g o vv.. i n
n>
Standardization of Dry-distillation Technique
for the Recovery of Radioiodine
Irradiated Tellurium Matrix
B . S . To m a r < b s t o m a r @ b a r c . g o vv.. i n >
In view of important therapeutic and diagnostic applications of
different isotopes of radioiodine such as
.
from
(131, 120, 123, 124)
I, an
attempt has been made to optimize the dry thermodistillation
technique for the recovery of radioiodine in carrier-free form
Preparation
of
radioisotope
from irradiated tellurium matrix.
endofullerenes
The discovery of fullerenes in 1985 triggered a worldwide interest
Most of the biomedically important radioiodine isotopes are
in its possible applications in various branches of science and
produced by accelerator irradiation except 131I which is produced
technology and also in medical science. One of the most
by thermal neutron irradiation in a nuclear reactor. For
interesting developments in this context is the encapsulation of
standardization work, 131I radioisotope, produced by thermal
atoms in the fullerene cage forming endofullerenes. It may not
neutron irradiation of natural TeO2 (70-90 mg) in DHRUVA reactor
be possible to produce endofullerenes by conventional chemical
at BARC, Mumbai, was used. The initial experimental work on
reactions.
the isolation of 131I from irradiated Te-matrix by thermodistillation
technique produced satisfactory results. Different long-lived
One possibility is to put energetic atoms through the fullerene
radioisotopes of Te (i.e., 121Te, 123Te and 129Te), produced by (n,γ)
molecules. We have produced several radioisotope endofullerenes
nuclear reactions, were used to monitor the level of co-distilled
by implanting energetic recoils obtained from heavy ion induced
Te in the separated 131I distillate by gamma-spectrometry. The
nuclear reactions. The high energy (80 - 140 MeV) heavy ion
inactive Te content in different 131I-distillates was found to be in
beams of
16
O,
15
N and
20
Ne from VEC machine were used to
the range of 1.1-4.0 ppm by radiometric analysis.
produce various recoiled isotopes from targets like Cu, As, Tb.
The process involved implantation of recoils in fullerene by
Further work is in progress to optimize different parameters in
irradiation and then chemical extraction of endofullerenes in
order to obtain higher yield of radioiodine with reproducible
organic solvent by highly acidic aqueous medium. The following
values as well as in the recovery of target material.
radioisotope endofullerenes were produced :
H e a d , A C D < h e a d a c d @ b a r c . g o vv.. i n >
Chemical Sciences & Engineering
BARC HIGHLIGHTS
17