Hanford Tank BY-108 Thermal Oxidation System Performance Testing Methodology - 21055

In 2014, the Tank Vapor Assessment Team identified the need to provide engineered controls to protect tank farm workers from toxic organic vapors emitted from Hanford high-level waste tanks. Toxic organic species found in the vapor phase are referred to as chemicals of potential concern (COPCs). In response to this need, NUCON International, Inc. (NUCON) presented a proposal to the 2016 U.S. Department of Energy Office of River Protection Grand Challenge competition for treating headspace COPCs using a novel thermal oxidation system (TOS). The TOS directs tank vapors to an internal combustion engine, where they are destroyed in-cylinder by the engine combustion and the engine's exhaust after treatment. NUCON developed a prototype of the proposed system and conducted proof-of-concept tests (Phase 1). Upon successful completion of NUCON's proof-of-concept testing, Washington River Protection Solutions (WRPS) partnered with Pacific Northwest National Laboratory (PNNL) to conduct an engineering-scale evaluation (i.e., Phase 2) using a modified version of the NUCON TOS. The Phase 2 testing was conducted by selecting 11 COPC surrogates (out of 61 identified COPCs in total) and quantitatively measuring them at various points in the TOS. These measurements were performed using both online instruments and grab samples and were reported in 2019. The Phase 2 TOS testing concluded that 8 of the 11 COPCs were successfully removed to the target criterion (95% destruction) and all but one could be detected down to 10% of the occupational exposure limit. Though the testing was successful, Phase 2 testing was focused on 11 COPC compounds; consequently, testing was not performed with complex mixtures of COPCs (as would be found in Hanford tank headspaces) nor did it demonstrate successful operation of the MERSORB^R bed (mercury-selective adsorption functionality). Therefore, to evaluate the full functionality of the TOS, WRPS decided to proceed with planning for a Phase 3 demonstration test to be performed in the Hanford tank farm. After a site selection process, Hanford tank BY-108 was chosen as the candidate tank for the Phase 3 TOS testing. Currently, the design of the NUCON TOS planned for deployment at Hanford tank BY-108 is nearing completion. In parallel with the TOS design and fabrication process, PNNL developed a set of Phase 3 testing objectives and metrics to critically assess 'real-world' performance of the TOS system. An important part of the testing methodology is to collect Phase 3 performance data using a sampling system that will be co-located with the TOS at BY-108. The sampling system is designed to collect a series of sorption tube, cartridge, and canister samples to measure COPC levels simultaneously at TOS inlet (BY-108 vapor stream) and outlet (exhaust) locations. The TOS methods, objectives, and metrics developed by PNNL to support Phase 3 testing were selected to define TOS operating effectiveness and potential for protecting Hanford workers from harmful vapor exposure. (authors)