[en] Softi (study of optical fibres and components under thermal ageing and irradiation) is an on-going 6-year program intended to determine the effects of ageing on the behaviour of optical fibres and their fiber-end components. In this paper we present intermediate results of long-term and low dose-rate experiments performed with ¹⁶N gamma rays at the experimental nuclear reactor Osiris of Cea at Saclay. 3 batches of fibres have been tested: Spectran multi-mode, Spectran single-mode and 3M single-mode. The results show that: 1) the Spectran multi-mode fibre (which is a pure silica core step index fibre) presents a low induced attenuation with a significant ability to recover when irradiation stops, 2) the Spectran single-mode fibre presents a more important induced loss and its recovery is rather poor even after irradiation resumes after many days of interruption, and 3) the 3M single-mode fibre exhibits a more pronounced difference between the measurements at 1310 and 1550 nm than the 2 other batches, and the induced loss restores better at shorter wavelengths. (A.C.)