Threshold voltage (Vth) and drain-source current (IDS) behaviour of nitride read only memories (NROM) were studied both in situ during irradiation or after irradiation with photons and ions. Vth loss exhibits a variability well explained by the same Weibull statistics regardless of the irradiation species and total dose. Preliminary measurements of IDS in-situ during irradiation with photons show a step-like increase of the current with the total irradiation dose.