Development of a Nitric/Formic Acid process to reduce hydrogen emissions during sludge treatment in the DWPF

摘要

A new Nitric/Formic Acid (N/FA) flowsheet was developed at the Savannah River Technology Center (SRTC) for use in the Chemical Processing Cell (CPC) of the Defense Waste Processing Facility (DWPF). The flowsheet was successfully demonstrated with simulated sludge using a 2 L bench-scale experimental system and a one-fifth scale (4000 L) pilot facility, and with actual radioactive waste using a 0.1 L apparatus in one of the SRTC shielded cells. Overall, the new N/FA flowsheet compared to the original formic add flowsheet reduced the peak H(sub 2) generation rate by more than a factor of two and resulted in a more gradual rise in the H(sub 2) evolution. Therefore, implementation of the new N/FA flowsheet in the DWPF CPC would result in an increased margin of safety and possibly a reduction in the scope and cost of modifying the DWPF CPC vessel vent system. Also, the new N/FA flowsheet would be compatible with Tank Farm processes and other DWPF flowsheets, and with the implementation of the new Late Wash flowsheet in the DWPF, it would be key to maintaining a proper redox balance of the melter feed.