This paper outlines the motivation for structural health monitoring with fiber Bragg grating (FBG) strain sensors in nuclear power plants where a high measurement resolution is normally required. Hence, a mechanical strain amplification is needed to increase the strain sensitivities. To ensure long-term stability, an epoxy-free mechanical strain amplification sensor is constructed using a Kovar encapsulated FBG. The strain response of the sensor is characterized using an extensometer. It was found that the achieved sensitivity of 1.16 ± 0.008 pm/µε yields a strain resolution of 0.43 ± 0.003 µε with current interrogation method -which exceeds the required strain resolution for the postulated scenario. However, if a higher resolution is required, it can be achieved by using an interrogator with a higher wavelength resolution or using a strain amplification with a larger strain amplification coefficient.