University of Canterbury
Spatial Multi-taper Spectral Analysis
Spatial spectral analysis is used to identify spatial structure in temperature measurements from a nuclear reactor core.
The multi-taper spectrum estimation method of Thomson (1990) is adapted for spatial processes, to optimally minimise the bias due to spectral leakage and to improve the variance properties of the spectrum estimate. The exact tapers required for the reactor region are calculated using a powering method. The spatial spectrum is used to identify the regular (and deterministic) effects of the reactor geometry on the temperatures, and the non-deterministic and stochastic structure due to the complex interactions involved. The spatial cross-spectrum is used to explore the relationship between the fuel irradiation and reactor temperatures.
The results are used to construct a random effects model to predict the reactor temperatures and to improve the performance of a reactor physics model under development by the UK nuclear industry.