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.2020-03-312020-03-31CORREA, 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. <b>Abstract...</b> Lisboa, Portugal: C2TN, Instituto Superior Técnico, Universidade de Lisboa, 2019. Disponível em: http://repositorio.ipen.br/handle/123456789/31018.http://repositorio.ipen.br/handle/123456789/31018Introduction – 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.openAccessResumo de eventos científicos0000-0003-3237-8588https://orcid.org/0000-0002-9351-9201https://orcid.org/0000-0003-3237-8588