Through a thesis and a project funded by the LNE, the LNHB is developing a prototype for the detection of illicit materials using the active photon interrogation method, based on the spectrometry of photoneutrons emitted by targets irradiated by a linear electron accelerator. This new thesis topic involves studying photonuclear reactions on light elements for environmental applications, primarily through a better understanding of photoneutrons, secondary neutrons and cosmogenic radionuclide production rates in the atmosphere during terrestrial gamma ray flashes associated with thunderstorms or gamma-ray bursts of cosmic origin. The LNHB-MD's unique experimental facility will be use to obtain basic nuclear data, such as the angular and energy distributions of photoneutrons emitted by light elements, and to characterize activation products. The data collected will be use to improve the description of photonuclear processes for light elements in Monte-Carlo codes, and to estimate their influence on measurable quantities through simulation codes for environmental phenomena. The same methodology can be apply to the study of photonuclear reactions in rocks - composed mainly of light elements - following irradiation by high-energy photons of natural or artificial origin.