In-core temperature measurement for the PBMR using fibre-bragg gratings

[摘要] The PBMR has called for research into the possibility of distributed in-coretemperature measurement. In this thesis, several methods for distributedtemperature measurement in high-pressure, -radiation and -temperature environmentshave been investigated by means of a literature study. The literaturestudy has revealed FBG temperature sensors as the most feasible solutionto the temperature measurement challenge.Various parameters affecting the propagation of light in optical fibresand consequently the FBG reflection profile was researched. The differentialequations describing FBG structures were solved and implemented inMatlab in order to simulate WDM of a distributed FBG sensing system. Distributedsensing with apodized FBGs written in sapphire optical fibre showthe most promise of becoming a solution to the measurement challenge.However, practical testing of sapphire FBGs exposed to the environmentin the PBMR core is required. With this long-term goal in mind, a generaltest platform for FBG temperature sensors was assembled. A heater controllerwas built for a specialized fibre heating element capable of controllingthe temperature of a single FBG up to 1600 C. Temperature measurementusing wavelength division multiplexing of apodized FBGs written in silicaoptical fibre were demonstrated in the test platform with great success. Themeasured results corresponded very well with the theory.Finally, the implementation of FBGs in the PBMR is discussed and recommendationsare made for future work

[发布机构] Stellenbosch University