Page 64 - PR 2014 2016 07 Nuclear Science and Technology

206 Nuclear Science and Technology | Progress Report

tillation, gross alpha and beta counting, and Internal dosimetry: Routine
thermoluminescent dosimetry are employed.
The workers that carry out activities with un-
The Institutional PMRA has shown over the sealed sources are routinely monitored to
years that the radiological environmental im- demonstrate that they are receiving adequate
pact of IPEN’s facilities is negligible, as the protection to internal contamination. Direct
effective doses to members of the public are measurements of whole-body and thyroid
several orders of magnitude lower than the contents provide an estimation of the radionu-
recommended levels. clide activity incorporated by the potentially
exposed workers. These measurements are
Determination of radionuclides in carried out for workers, trainees and visitors
foodstuff and commodities and are routinely performed by the In Vivo
Monitoring Laboratory, LMIV. The frequency
Several analytical techniques are available and of measurements is defined by the Radiopro-
offered in the form of providing services to tection Service (SRP) and the Dose Calcula-
the private sector. Available analyses include: tion Group of IPEN. For this purpose, LMIV are
determination of gross alpha and beta activ- equipped with two measurement systems:
ities; determination of natural and artificial the whole body counter, NaI(Tl) (8x4”), and the
gamma emitters; determination of uranium, thyroid counter, NaI(Tl) (3x3”). The counting
thorium and radium isotopes; determination room dimensions are 2.6 m x 1.7 m x 1.85 m
of 210 Pb and 222 Rn; determination of radionu- and the walls are made with 130 mm-thick
clides in foodstuffs and commodities imported steel sheet lined with 5 mm of lead and 5
and exported by Brazil; and determination of mm of copper. This room is climatized and
90Sr in foodstuffs and food commodities; and the temperature is mantained at 25°C. The
determination of 3H in water. measurement system is calibrated in energy
241
and efficiency, with sources of Eu, Am and
152
60 Co with gamma emissions between 59.54
and 1,408.08 keV, positioned within Alderson
Research Labs anthropomorphic phantom.
The background measurements spectrum is
obtained from workers that were not exposed
occupationally. The concepts adopted in the
HPS N13.30 Standard and proposed in ISO
documents for standardization are used for
activity measurements. The dose calculation
follows the measurements of the activity in
excreta or in body tissues. The calculation of
activity in body compartments and the com-
mitted dose estimates are carried out with
the software “Activity and Internal Dose Esti-
mates”, AIDE. These calculations are based on

Figure 44. The renewed sample preparation laboratory the mathematical models recommended by
for the characterization of radioactive effluents produced the International Commission on Radiologi-
by IPEN’s facilities, for the execution of the Institution-
al Environmental Radiological Monitoring Program. cal Protection, and adopted by the Brazilian

Instituto de Pesquisas Energéticas e Nucleares