Future circular and linear colliders including FCC, as well as the Large Hadron Collider in the High-Luminosity era have been imposing unprecedented challenges on the radiation hardness of particle detectors that will be used for specific purposes e.g. forward calorimeters, beam and luminosity monitors. We performed research on the radiation-hard active media for such detectors, particularly calorimeters, by exploring intrinsically radiation-hard materials and their mixtures. The initial samples that we probed were thin plates of Polyethylene Naphthalate (PEN) and Polyethylene Terephthalate (PET) and thin sheets of HEM. The previous studies indicate towards promising performance under high radiation conditions. We report on the necessary process of mixing PEN and PET for optimized scintillation and signal timing properties preserving the high radiation resistance. Recently we developed a new plastic scintillator material, tested it in particle beams and obtained promising results. In recent studies, we investigated the radiation damage to plastic scintillators, various special glasses and scintillating fibers together with their recovery mechanisms. Here we report on the development of radiation-hard scintillators and the irradiation studies together with the investigation of the recovery mechanisms.