Signal estimation and change detection in tank data for numerical safeguards

Burr, T.*; Suzuki, Mitsutoshi; Howell, J.*; Jongo, C. E.*; Hamada, M. S.*

Process monitoring (PM) is increasingly important in nuclear safeguards as a complement to mass-balance based nuclear materials accounting (NMA). Typically, PM involves more frequent but lower quality measurements than NMA. While NMA estimates special nuclear material (SNM) mass balances and uncertainties, PM often tracks SNM attributes qualitatively or in the case of solution monitoring (SM) tracks bulk mass and volume. Automatic event marking is used in several nuclear safeguards PM systems. All methods are evaluated on both raw and smoothed data, and several smoothing options are compared, including standard filters, hybrid filters, and local kernel smoothing. The main finding is that for real and simulated examples considered, a two-step strategy is most effective. First, any reasonably effective initial smoother is used to provide a good initial guess at change point locations. Second, PLR is applied, looking for one change point at a time.