Waste behavior during horizontal extrusion: Effect of waste strength for bentonite and kaolin/ludox simulants and strength estimates for wastes from Hanford waste tanks 241-SY-103, AW-101, AN-103, and S-102

The Hanford Site has 149 single-shell tanks (SSTs) and 28 double-shell tanks (DSTs) containing radioactive wastes that are complex mixes of radioactive and chemical products. Some of these wastes are known to generate mixtures of flammable gases, including hydrogen, nitrous oxide, and ammonia. Nineteen of these SSTs and six of the DSTs have been placed on the Flammable Gas Watch List because they are known or suspected, in all but one case, to retain these flammable gases. Because these gases are flammable, their retention and episodic release pose a number of safety concerns. Understanding the physical mechanisms and waste properties that contribute to the retention and release of these gases will help to resolve the Flammable Gas Safety Issue. The strength of the waste plays a central role in the mechanisms of both bubble retention and bubble release. While recent in-situ measurements from the ball rheometer have provided results for five of the DSTs, waste strength measurements are typically not available for any of the SSTs or for the DSTs that have not been characterized with the ball rheometer. The overall purpose of this study is to develop a method to obtain strength estimates for actual wastes from observations of the wastes` behavior during extrusion from core samplers. The first objective of the study was to quantify waste behavior during horizontal extrusion by documenting the extrusion behavior of simulants with known strengths; the second was to estimate the strength of actual waste based on these simulant standards. Results showed a reproducible extrusion behavior for bentonite clay and kaolin/Ludox{reg_sign} simulants over strengths ranging from 30 to 6,500 Pa. The extrusion behavior was documented with both video recordings and still images. Based on these visual standards, strength estimates were made for wastes from DSTs 241-SY-103, 241-AW-101, and 241-AN-103 and SST 241-S-102