Determination of Rn-222 emanation fraction and diffusion coefficient in concrete using accumulation chambers and the influence of humidity and radiumdistribution

In this paper we present a laboratory method for the determination of diffu sion coefficient, D, as well as the Rn-222 emanation fraction, f, in concre te core samples. It is based either on the analyses of the growth curves of the radon in the air volume surrounding a sample enclosed in an accumulati on chamber (Lucas cell or RADIM device) or using the charcoal adsorption me thod. Samples used have a special geometry allowing the assumption of a one -dimensional diffusion of radon in material. Radium was enhanced in the con crete samples by adding radium bromide solution or uranium ore. A strong de pendence of the emanation fraction on the enhancing method was observed. Fo r the sample enhanced with uranium ore the specific exhalation rate was abo ut ten times smaller. A marked dependence of radon exhalation on the water content was also observed. (C) 2001 Elsevier Science Ltd. All rights reserv ed.