DISCLAIMER'letter reporting refinement of flammable gas generatiodretention models using void meter and retained gas sampling data."The data obtained from operating the void fraction instrument 0 (Stewart et al. 1996a), and retained gas sampler (RGS) (Shekarriz et al. 1997) have determined the amount and composition of gas retained in the wastes in the six double-shell tanks on the Flammable Gas Watch List (Johnson et al: 1997). The interpretation of those data and the models for gas retention and release developed or improved as a result represent significant progress toward an adequate understanding of the mechanisms of gas generation, retention, and release. This report summarizes the VFI and RGS data and presents the models these data have enabled us to develop.. iii AbstractThis report describes the current understanding of flammable gas retention and release in Hanford double-shell waste tanks AN-103, AN-104, AN-105 The applicable data available from the void fraction instrument, retained gas sampler, ball rheometer, tank characterization, and field monitoring are summarized. Retained gas volumes and void fractions are updated with these new data -Using the retained gas compositions from the retained gas sampler, peak dome pressures during a gas burn are calculated as a function of the fraction of retained gas hypothetically released instantaneously into the tank head space. Models and criteria are given for gas generation, initiation of buoyant displacement, and resulting gas release; and predictions are compared with observed tank behavior. V Summary .The gas retention and release behaviors of Hanford double-shell tanks (DSTs) on the Hammable Gas Watch List (FGWL), were characterized in detail using the ball rheometer and void fraction instrument 0 from December 1994 to May 1996. These are reported in Stewart et al. (1996a). Additional data on gas .composition and void fraction have since become available on four of these tanks (AW-101, AN-103, AN-104, and AN-105) using the retained gas sampler (RGS) from March through September 1996 and are described in Shekarriz et al. (1997).The main objective of the work presented in this report is improving the models for gas retention and release based on these data and updating the original gas retention and release calculations with the new RGS and core sample data-Because of this extensive characterization effort, we have a better knowledge and understanding of these DSTs than of any other Hanford tanks. We include models that help explain current gas retention and release behavior and examine the potential for other tanks to exhibit hazardous episodic gas releases. The models developed for gas generation based on waste sample testing are also summarized. While none of these models have been formally ve$i,ed and validated for safety analysis, they are consistent with the extant body of data and observations. The updates to earlier calculations and improvements to gas generation, retention, and release models are summarized below. G a s Generation Models and ...

Processing of hazardous materials is a crucial example where online monitoring can significantly reduce operation risk, cost, and time. This is particularly true in the case of the Hanford site, where nuclear materials from the Cold War era are being processed for environmental cleanup efforts. In exceedingly complex streams such as those at Hanford, online and real-time monitoring can be challenging due to the complexity of instrument signals. Further obstacles are imposed by the caustic nature of processing streams, as well as the radiation damage inflicted on instruments and probes. Online monitoring based on Raman spectroscopy enables the detection of many Hanford tank species of interest. Nine chemical species that comprise the majority of tank waste by volume, including Al­(OH)4 –, C2O4 2–, CO3 2–, CrO4 2–, NO3 –, NO3 –, OH–, PO4 3–, and SO4 2–, were detected and quantified. Real-time analysis of Raman signal allows for immediate quantification of target analytes and was successfully accomplished through the use of chemometric models. Furthermore, irradiation tests revealed that Raman monitoring systems can effectively continue to operate even after receiving 1 × 107 rad of γ dose. The online, real-time monitoring system developed here was successfully used to simultaneously quantify nine target analytes in a real sample collected from Hanford tank AP-105.

Microfluidic devices are a growing field with significant potential for applications to small scale processing of solutions. Much like large scale processing, fast, reliable, and cost-effective means of monitoring streams during processing are needed. Here we apply a novel micro-Raman probe to the online monitoring of streams within a microfluidic device. For either macro- or microscale process monitoring via spectroscopic response, interfering or confounded bands can obfuscate results. By utilizing chemometric analysis, a form of multivariate analysis, species can be accurately quantified in solution despite the presence of overlapping or confounding spectroscopic bands. This is demonstrated on solutions of HNO and NaNO within microflow and microfluidic devices.

Development of more effective, reliable, and fast methods for monitoring process streams is a growing opportunity for analytical applications. Many fields can benefit from online monitoring, including the nuclear fuel cycle where improved methods for monitoring radioactive materials will facilitate maintenance of proper safeguards and ensure safe and efficient processing of materials. Online process monitoring with a focus on optical spectroscopy can provide a fast, nondestructive method for monitoring chemical species. However, identification and quantification of species can be hindered by the complexity of the solutions if bands overlap or show condition-dependent spectral features. Plutonium(IV) is one example of a species which displays significant spectral variation with changing nitric acid concentration. Single variate analysis (i.e., Beer's Law) is difficult to apply to the quantification of Pu(IV) unless the nitric acid concentration is known and separate calibration curves have been made for all possible acid strengths. Multivariate or chemometric analysis is an approach that allows for the accurate quantification of Pu(IV) without a priori knowledge of nitric acid concentration.

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