Evaluation of the maximum emitting layer of Rn-222 in cementitious building materials
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2019
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INTERNATIONAL CONFERENCE ON DOSIMETRY AND ITS APPLICATIONS, 3rd
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Introduction – Radionuclides present in construction materials are of interest in the view of
environmental radioactivity. The limitations established have focused on the concentration of
Ra-226 and the consequent exhalation of Rn-222. A physical/mathematical model developed
at the Laboratory of Applied Nuclear Physics (LFNA/UTFPR) correlates the exhaled Rn-222
with the Ra-226 inherent to the material. The model considers the exhalation of Rn-222 by
a plane surface that simulates exhalation in fl oors, walls and ceilings. Determination of the
maximum emitting layer of Rn-222 that effectively exhales is important to support the model.
The objective of this research is to determine the maximum emissive layer of Rn-222 that
provides internal diffusion and exhalation of radon-222 in cementitious materials.
Methods - Cylindrical samples were made of common cement paste and cement paste with
sand of high Ra-226 concentration. The samples (thicknesses 1 to 5 cm) were sealed in order
to ensure the exhalation of Rn-222 through one surface. Samples and diffusion chambers
containing CR-39 solid-state detectors were inserted into a glass vessel. The samples/detectors
were stored for 30 days. Subsequently, the detectors were chemically etched and the nuclear
tracks in the CR-39 detectors were counted.
Results – For each type of sample a curve was fi tted whose threshold indicated the maximum
emitting layer. The results obtained on the samples of common cement paste indicated a
maximum emitting layer of 2cm. For samples of cement paste with sand with high Ra-226
concentration, no threshold was observed, indicating that the maximum emitting layer is
greater than 5cm.
Conclusions - The maximum emitting layer thickness of Rn-222 of common materials
determined by curve fi tting was 2cm. For materials with high concentration of Ra-226 there
is an indication that the emitter layer is larger than 5cm. The obtained results subsidize the
physical/mathematical model developed in the LFNA/UTFPR.
Como referenciar
CORREA, J.N.; PASCHUK, S.A.; BARRETO, R.C.; DENYAK, V.; SCHELIN, H.R.; NARLOCH, D.C.; DEL CLARO, F.; HASHIMOTO, Y.; MATIN, A.C.; SILVA, A.C.M.; ZAHN, G.S.; SILVA, P.S.C. Evaluation of the maximum emitting layer of Rn-222 in cementitious building materials. In: INTERNATIONAL CONFERENCE ON DOSIMETRY AND ITS APPLICATIONS, 3rd, May 27-31, 2019, Lisboa, Portugal. Abstract... Lisboa, Portugal: C2TN, Instituto Superior Técnico, Universidade de Lisboa, 2019. Disponível em: http://repositorio.ipen.br/handle/123456789/31018. Acesso em: 24 Apr 2024.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.