Eddy current is a well-established non-destructive examination (NDE) technology for detection of service-induced degradation in metal components. For application to the inspection of dry storage casks for used nuclear fuel eddy current techniques (ECT) have advantages over conventional ultrasonic (UT) techniques in that eddy current probes can be much more compact than probes for UT and ECT can readily be implemented without the requirement of a coupling to the specimen under investigation for efficient transmission of inspection signals. However flaw depth sizing is one function where UT is more suited than ECT due to the limited penetration ability of electromagnetic signals into highly conductive materials. While UT could be deployed for the purpose of depth sizing flaws in dry storage canisters the implementation will be somewhat cumbersome due to the limited accessibility. Thus considerable advantage can be gained from development of advanced ECT for flaw depth sizing in dry storage casks with probes that can be realized in compact packages. This paper will provide an overview of advanced ECT giving consideration to the suitability of techniques and technologies to the given application. In addition this paper will describe progress on development of a multi-frequency eddy current technique for characterizing cracks in dry storage casks.