Test Plan for Empirical Benchmarking of Guided Ultrasound For Liquid Water Sensing

Abstract

This document provides test plan recommendations for the empirical benchmarking of modeling and simulation performed to predict the response of guided ultrasonic wave (GUW) signals to liquid water remaining in dry storage casks following drying. Some uncertainty exists regarding the quantity of residual water potentially left behind in a cask following drying because water can become trapped in cavities or other small crevices in the surfaces formed by the fuel cladding, fuel assemblies, and other internal hardware components. Further, excess liquid water can remain if drying processes are not executed as intended. This has motivated investigation of GUW as a modality for sensing of liquid water remaining in casks after drying. Significant advantages of the GUW modality include the ability to propagate over significant distances in structural components, enabling comprehensive coverage with a limited number of sensors. Further, GUW can be implemented non-invasively. That is, liquid water inside of the cask can be detected via sensor mounted to the external surface. Therefore, no penetration or opening of the cask is required. Candidate systems identified for benchmark testing include actual canisters (unused) that the United States Department of Energy (DOE) received from San Onofre Nuclear Generating Station (SONGS) and a comprehensive 2/3 scaled mockup at the University of Southern California (USCal). The mockup at USCal was initially developed through funding from a DOE office of Nuclear Energy integrated research project awarded in FY2016. Although the SONGS canisters offer the opportunity to perform testing on actual full-scale systems, they do not include fuel assembly hardware. Conversely, the USCal mockup is not full-scale, but it provides a comprehensive system model with surrogate fuel assemblies. In total, the test plan recommends up to 60 measurements on SONGS canister and USCal mockup systems conducted with system complexity increasing in the following sequence: • Unloaded baseplate • Baseplate with basket loading • Baseplate with basket and fuel loading • Baseplate with liquid water loading • Baseplate with combined loadings of basket, fuel, and liquid water In addition, the end of this document also includes a summary of a proposed effort to evaluate likelihood of water removal from a water logged failed fuel rod.