Page 363 - 00. Complete Version - Progress Report IPEN 2014-2016

Nuclear Safety | Progress Report 363

a three-D visualization of the content of the costs with relatively high efficiency.
drums in terms of radionuclides present and
their respective concentrations.

The system operates in continuous and pro-
grammable mode, and allows the number of
measurements, operation time and the axi-
al positioning of the detector relative to the
drum to be preset.

The calibration of efficiency of the system
used four standard drums with different den-
sities that mock up actual waste drums: com-
pressed paper, water, sand and concrete. Five
water-equivalent solid standards containing
Figure 5 – Gamma Scanning System developed by GRR
Eu-152 were prepared in rod geometry with
density of 1.15 g.cm-3.
Biosorption of thorium from aqueous
The acquisition of data and the interpretation solutions by hydroxyapatite.
of results of the operation of the system use
computational algorithms based on the Monte Bone meal is a biological material that reunites
Carlo Method and Artificial Neural Networks low cost and efficiency. It is a natural material
to characterize radioactive waste drums reli- that contains large amount of calcium phos-
ably and efficiently. phate, in the form of hydroxyapatite. Studies
with hydroxyapatite showed that this materi-
Biosorption of heavy-metal ions and al is efficient in removing heavy metals from
radionuclides from aqueous solutions. polluted soils due to their ability to adsorb
molecules and can be used to remove radio-
In the recent years, there is an increasing in- nuclides from liquid aqueous solutions, as liq-
terest in the application of biological materi- uid radioactive waste generated in many ac-
als for the removal of heavy metal ions from tivities. In the work done by GRR, bone meal
aqueous solutions. The biosorption is a tech- purchased in local market was chopped and
nique that uses biological material on remov- sieved to obtain particle sizes between 0.125
al of metals. A variety of biological materials, and 0.297 mm. Batch biosorption experiments
such as agriculture residues, bacteria, algae, were performed to determine the metal uptake
among others, proved to be efficient biosor- capacity and equilibrium time. Fixed concen-
bents. The use of these materials is attrac- trations of thorium solutions were prepared
tive and advantageous because they are in- by dissolving thorium nitrate in distillate wa-
expensive in comparison with commercial ter. The bone meal suspended in 5 mL of tho-
adsorbents. Biosorption shows great potential rium solutions in a ratio of 0.2% w/v was left
among many possible techniques for treating in contact during different times: 0.5, 1, 2 and
radioactive liquid waste since it is capable of 4 hours. After the contact time, the bone meal
decontaminating large volumes of waste con- was removed by filtration and the superna-
taining low concentrations of metals at low tant, analyzed by inductively coupled plasma