Page 199 - 00. Complete Version - Progress Report IPEN 2014-2016

Nuclear Science and Technology | Progress Report 199

sure index only the Iberê Crema Bordeaux and risk index (Hex) and also the absorbed dose
Iberê Mombasa granites indicate limitations rate (D) and annual effective dose (Def) were
when applying as surface material. However, calculated from the activity concentrations of
232
considering the gamma exposure index, the 226 Ra, Th and 40K. The activity concentration
granites Cinza Corumbá, Cinza Andorinha, Am- values for 226 Ra ranged from under the min-
arelo Icaraí, Cinza Ocre, Iberê Crema Bordeaux imum detectable activity to 38.7 Bq·kg1, for
and Iberê Mombasa have controlled applica- 232 Th from under the minimum detectable ac-
tion. In conclusion, the evaluated granites and tivity to 101.2 Bq·kg1 and for 40K from under
all marbles evaluated have viable applications the minimum detectable activity to 256 Bq·kg1.
in different activity sectors and for different Raeq ranged from 1.41 Bq·kg1 to 203 Bq·kg1, Iδ
purposes and the granites that exceeded the ranged from 0.0047 to 0.720, Hin from 0.0076
proposed limits should not be applied in the to 0.653 and Hex from 0.0038 to 0.549. The ab-
interior of residences. sorbed dose rate ranged from 0.170 nGy·h1
to 21.3 nGy·h1 and the annual effective dose
Assessment of natural radioactivity in ranged from 0.83 μSv to 104.2 μSv. The results
wall paints of commercial use in Brazil show that the activity concentrations of the
wall paints studied in this work are below the
Natural radioactivity in soils, rocks and con- recommended limits by Hassan et al. for Raeq
struction materials, due to 40K and the nat- (370 Bq·kg1), by European Commission for Iδ
ural series of 232 Th and 238 U, is the main con- (limit of 2 for superficial materials) and by the
tribution to external exposure in mankind. Organisation for Economic Co-operation and
Activity concentrations of 226 Ra ( U series), Development for Hin and Hex (both with limit
238
232 Th and 40K were determined for 50 white of 1), for all the 50 samples, assuring the safe-
latex wall paints samples, commercialized in ty of these wall paints with respect to radio-
Brazil, namely 15 Economic quality samples, logical protection.
15 Standard quality samples and 20 Premi-
um quality samples and for a single titani- The use of representative person and
um dioxide sample. The samples were tightly critical group concepts for environmental
sealed and stored for a minimum period of 30 control of nuclear facilities in Brazil
days, to reach the radioactive secular equilibri-
232
238
um from U and Th series, then measured According to the National Commission for Nu-
by high resolution gamma-ray spectrometry. clear Energy, CNEN, the assessment of environ-
The activity concentration was determined mental radiological impact from the release of
using the weighted average concentrations radionuclides to the environment due to nor-
of 214Pb and 214Bi for Ra and Ac, 212Pb mal operation of nuclear facilities, for protect-
228
226
and 212Bi for Th. The 40K activity concen- ing the public, considers the concept of critical
232
tration was determined by its single transition group. In 2006, the International Commission
of 1460.8 keV. Self-attenuation correction fac- on Radiological Protection (ICRP), for the same
tors of the samples whose densities are higher purpose, proposed the adoption of the concept
than 1.0 g·cm3 were determined and used to of representative person. Once, at some point,
make the necessary corrections. The radiolog- this new concept probably will be adopted
ical indices radium equivalent activity (Raeq), in Brazil. The changes in terms of procedures
activity concentration index (Iδ), internal ex- for calculating and consequent results aris-
posure risk index (Hin) and external exposure ing from the application of the representative