PVC samples were irradiated for 1 hour with a thermal neutron flux of Φ@'t@'h = 4.71 @ 10 1 1 n @ cm @ 2 @ s @ 1 and the chlorine lost during irradiation was measured by γ-ray spectrometry. About 15% of loss of chlorine has been observed for untreated samples while samples heated to temperatures of 60 and 80 °C for one minute before irradiation have been found to loose about 8% and 3%, respectively. The results indicate an influence of the polymer structure on the release of chlorine.