Assessment of alternative mitigation concepts for Hanford flammable gas tanks

This report provides a review and assessment of four selected mitigation concepts: pump jet mixing, sonic vibration, dilution, and heating. Though the relative levels of development of these concepts are quite different, some definite conclusions are made on their comparative feasibility. Key findings of this report are as follows. A mixer pump has proven to be a safe and effective active mitigation method in Tank 241-SY-101, and the authors are confident that mixer pumps will effectively mitigate other tanks with comparable waste configurations and properties. Low-frequency sonic vibration is also predicted to be effective for mitigation. Existing data cannot prove that dilution can mitigate gas release event (GRE) behavior. However, dilution is the only concept of the four that potentially offers passive mitigation. Like dilution, heating the waste cannot be proven with available information to mitigate GRE behavior. The designs, analyses, and data from which these conclusions are derived are presented along with recommendations