Irradiation induced field fluctuations in graphite

► We have developed, using MC calculations, an algorithm to predict the behaviour of porous materials in hostile environment. ► We have demonstrated that ion irradiation induces electrical heterogeneity in porous media. ► We found that the key parameter that affects the induced electric fields is the spatial distribution of the inclusions. ► We have shown that the field intensity enhancement in flawed samples reaches several orders of magnitude. ► We have related the developed hot spots to the sudden release of the energy stored in neutron irradiated graphite.