PI/Co–PI: Jim Smart, PhD and Fuqian Yang PhD ( University of Kentucky)
Keywords: CVD, nickel, radionuclide contamination, electro-refinement, hazardous waste
Rationale. The U.S. Department of Energy (DOE) has accumulated 40,000 tons of nickel metal ingots at several of their facilities in the U.S. These nickel ingots are contaminated with various levels of radionuclides. These stockpiles have accumulated over the years as a result of maintenance and decommissioning of uranium processing and enrichment facilities. These supplies cannot be disposed of in the open market because of a moratorium imposed by DOE that prohibits the sale of any recovered metal products that are volumetrically–contaminated with radionuclides.
The Paducah Area Community Reuse Organization (PACRO) has instigated efforts to explore technologies to purify and recover existing radiologically–contaminated nickel ingots at the Paducah Gaseous Diffusion Plant. PACRO has performed careful analysis of samples of nickel from existing open–market suppliers within the U.S. These analytical results will be the benchmark for nickel sales. It is believed if the DOE nickel ingots can be cleaned–up to either non–detect levels of radionuclides or at levels less than those existing in open market supplies, DOE will allow relaxation of moratorium restrictions and release purified nickel ingots for public sale.
Proposal. Two promising technologies will be investigated for recovery of radiologically–contaminated nickel supplies. These include: (1) chemical vapor deposition (CVD) and (2) enhanced electro–refining (ER) technology. Recovery feasibility will be demonstrated in laboratory–scale reactor systems. Results from these tests will be used to design and construct full–scale reactor systems for nickel recovery at the Paducah Gaseous Diffusion Plant.
Objectives:(a). To investigate the application of chemical vapor deposition (CVD) technology for the removal of radionuclides from radiologically–contaminated metal waste. If this technology proves to be a viable method of purification, design and test an advanced laboratory reactor suitable for industrial‑scale recovery of existing stockpiles of nickel waste.
(b). If CVD technology does not prove to be a suitable method for purification of radiologically‑contaminated metal waste, explore use of ER technology as a method of purification. If ER technology proves to be a viable method of purification, design and test an advanced laboratory reactor suitable for industrial‑scale recovery of existing stockpiles of nickel waste.
Innovation. A literature search reveals little to no work has been published for removal of radionuclides from metallic waste. Existing CVD equipment at the University of Kentucky will be modified to explore the feasibility of production of extremely pure nickel, utilizing the Mond Process. Also, advanced analytical tools at the University such as scanning electron microscopy, x–ray diffraction, and transmission microscopy will be used to carefully evaluate levels of residual contamination within the final pure nickel product. Initially, virgin nickel powder