[en] At the end of 1990, the long neglected National Film Archive of Romania began a modernization effort. A new building was built, with a controlled atmosphere and a modern storage system. Before relocation to the new building, the film reels showing fungal traces were cleaned using a special machine. The procedure included brushing and washing with a detergent. The structure of film favours fungal attack. Photographic film is made of a transparent support on which is applied a gelatin emulsion that includes silver atoms (black and white film) or organic dyes (colour film). Gelatin is a hydrophilic protein that remains dry in normal humidity, but can take water from the air if the relative humidity is high. Gelatin emulsion is an excellent source of food for fungi. As a consequence of contamination, part of the gelatin disappears. Instead, fungal metabolic by-products appear. They can chemically interact with the dyes or the support. Of course, the degradation is in direct proportion to the development of fungal attack. In a dry environment, fungi do not develop further and films can be considered stabilized. It was believed that the fungal attack on film reels in the National Film Archive was not active and that the traces of previous attacks would be washed away by the cleaning action. It was thought that there was no need for emergency action. The discovery of several hundred reels where contamination was active and had developed disastrously was a very unpleasant surprise. The signs of a potential disaster were obvious: — The presence of very aggressive contamination on a large number of reels; — The imminent destruction of the films if the biological attack was not stopped immediately; — The impossibility to act by the usual means, because the treatment capacity of the cleaning equipment was far below that needed for the intervention. Radiation decontamination was chosen. In Romania, this was the only available method for the decontamination of large volumes in a short time. The literature did not indicate any antecedent, and there was no information regarding irradiation side effects on films. Given these circumstances, the action was preceded by a programme of exploratory tests.