Characterization report for the ferrocyanide safety issue

Recently PNNL was tasked by DOE to develop and demonstrate a risk-based strategic approach to characterizing Hanford`s Nuclear Waste Tanks. This strategic approach was documented in a report entitled ``A Risk-Based Focused Decision-Management Approach for Justifying Characterization of Hanford Tank Waste``. In support of the general approach, a specific strategy for addressing each of the several safety issues associated with the tanks was developed. This report documents the approach for the Ferrocyanide Safety Issue. The purpose of this report is to describe a structured logic diagram (SLD) for determining the risk associated with the ferrocyanide tank safety issue and provide the supporting information for the SLD. The SLD addresses the resolution of risks resulting from the presence of ferrocyanide layers within the Hanford tanks. The informational requirements for determining risk from any reaction stemming from ferrocyanide are outlined in the SLD. This report will describe the potential paths to a successful resolution of the ferrocyanide safety issue. Complete development of the intervention pathway is outside the scope of this current activity. General descriptions of the approach, key components of the SLD, and conclusions are provided in the body of this report. The complete SLD, descriptions of each box shown in the SLD, a discussion on how to fill data needs, and a list of contributors is provided in the appendices.