(51a) Demonstration of An Integrated off-Gas Treatment System for the Head-End of a Nuclear Fuel Recycle Plant

Oak Ridge National Laboratory is conducting a coupled end-to-end (CETE) demonstration of advanced nuclear fuel reprocessing to support the Advanced Fuel Cycle Initiative (AFCI). As part of the broader CETE project, there will be a demonstration of an advanced head-end process, referred to as Voloxidation. This process is designed to condition the spent nuclear fuel (SNF) and release tritium contained in the fuel matrix. The demonstration of the voloxidation unit operation at the multi-kg scale, along with the subsequent dissolution of the voloxidized SNF, provides a unique opportunity to study the performance of an integrated off-gas treatment system.

During the voloxidation process a number of significant changes to the SNF occur: (1) the fuel is oxidized, (2) the fuel is converted to a free flowing powder, (3) a very significant portion of the tritium (99+%) is released and along with significant fractions of the other volatile fission and activation products, including iodine, carbon 14 (as carbon dioxide), and krypton, and (4) SNF powder is separated from the cladding. When this powder is dissolved, much, if not all, of the remaining volatile components are released.

Over the past two to three decades a number of technologies to recover and sequester volatile radionuclides were developed to various stages of maturity. Based on the levels of maturity and applicably to the scale of this demonstration, specific technologies were selected and equipment designed to recover the primary volatile fission and activation products (3H, 14C, 85Kr, and 129I) released during the head-end operations.

The off-gas from the dry voloxidation process as well as from the more traditional fuel dissolution process will be treated separately and the volatile components recovered. This talk will provide descriptions of the off-gas treatment systems for both the Voloxidation process and for the fuel dissolution process. Results from the initial operations of the CETE batch voloxidation and dissolution processes, and impacts of the processing parameters on the relative quantities of volatile components released to the off-gas systems will also be described.