Spent nuclear fuel at a number of U.S. locations is stored at independent spent fuel storage installations in dry cask storage systems (DCSSs) which commonly consist of a welded austenitic stainless steel canister within a larger concrete vault or overpack. A number of technical issues and research and data needs associated with extended spent fuel storage have emerged from recent gap assessments led by the U.S. Nuclear Regulatory Commission (NRC) the U.S. Department of Energy the U.S. Nuclear Waste Technical Review Board and the Electric Power Research Institute's Extended Storage Collaboration Program. Stress corrosion cracking of welded stainless steel was considered as one of the top priority technical issues and functional monitoring was identified as one of the top crosscutting issues that could potentially affect performance of various dry cask components.The work presented in this paper reviews and assesses the current state of technology for directly monitoring stress corrosion cracking as well as the important environmental conditions-including temperature humidity and chloride concentration-that could affect this degradation mechanism. A variety of techniques were identified to be potentially suitable for the application to extended storage ranging from detecting crack initiation and measuring propagation from stress corrosion cracking to measuring the chloride concentration in deliquescent solutions. Some techniques are well developed and commercially available but some require significant advancement to overcome limitations . Overall because of geometry space limitations and the high ionizing radiation of DCSSs all the monitoring methods must be modified and tailored for this application.This abstract is an independent product of the Center for Nuclear Waste Regulatory Analyses and does not necessarily reflect the view or regulatory position of NRC. The NRC staff views expressed herein are preliminary and do not constitute a final judgment or determination of the matters addressed or of the acceptability of any licensing action that may be under consideration at NRC.