In the wake of Fukushima accident, there is a need to intensify efforts to efficiently monitor the release of alpha emitting radionuclides caused by the core melt down or/and failure of first barrier containment of the nuclear fuel. As a consequence of the exposure of diethylene-glycol bis(allycarbonate) (CR-39) to alpha radiations (emitted from ²³²Th), radiation damage causes modification of its physico-chemical properties like absorbance, surface roughness and reflectance which could be correlated with the chemically etched track density, conventionally followed for the quantification of α-radiations offline. CR-39 based Fiber Optic Sensor (CRFOS) based on the reflectance measurement has been developed with an aim to monitor online the presence of α-emitting radionuclides (in/around a nuclear facility).