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An “Off-Gas and Waste Forms Strategy Workshop” was held in Washington, D.C. on January 31, and February 1, 2023, to review the current state of the art (baseline) technologies for capturing and immobilizing these volatile radionuclides in waste forms (WFs). The discussions in that workshop were used to develop a roadmap for future research and development to mature technologies that are presently not ready for use in a commercial reprocessing facility and develop and demonstrate technologies that provide more safety, more simplicity, or lower costs compared to the current baseline.

Two slides to be used as part of a larger multi-lab seminar on fuel reprocessing off-gas.

The engineering design process is utilized to evolve an idea into a deliverable. This progression can take years, so to experience as much of the full design process as possible, this internship period was dedicated to working on several projects in different phases of the process. The result is a completed engineering project which provides a foundation that can be used to conduct research on a system by performing experiments, collecting data, and making changes as necessary to improve the system and answer new questions.

Progress report presentation to DOE program representatives.

Slide deck for UK/US off-gas technology exchange meeting, presenting the summary from an engineering paper-study of UNF off-gas treatment. These slides were modified from a presentation by Robert Jubin, presented in Seoul, Korea in 2017

Slide deck for presentation during a two-day information exchange among off-gas researchers from the US and the UK, to include INL, PNNL, ORNL, and UK research personnel.

This presentation is a high-level overview of the research at INL for the capture and separation of krypton and xenon from used nuclear fuel reprocessing off-gas.

This is a summary of a more extensive report, written in collaboration with the GE-Hitachi BWR Owner's Group, detailing a study of BWR off-gas treatment. The study determined that aged charcoal continues to be effective for the delay of Kr and Xe through BWR off-gas treatment systems. It demonstrates the over-sized nature of existing charcoal beds, and highlights potential areas of improvement.

Reprocessing of used nuclear fuel (UNF) results emits several volatile radionuclides that must be removed from the bulk off gas prior to release in order to meet U.S. regulatory emission requirements. After other volatile radionuclides have been removed, krypton (Kr) remains, along with associated with xenon (Xe) in the gas stream. The half-life of Xe is short enough that by the time UNF is sufficiently cooled to be reprocessed Xe is no longer a radiological concern and it may be release to atmosphere or collected for other purposes. Kr, however, must be placed in long term storage. In order tomore » ensure the smallest practical volume for long term storage, the Xe, which is nearly ten times the volume of Kr, must be separated from the Kr. Although cryogenic distillation has been used successfully for this purpose, high capital and operational cost, along with safety considerations, made development of gas adsorption processes for separation of Xe and Kr attractive. INL developed an engineered form sorbent consisting of silver mordenite in a polyacrylonitrile matrix (AgZ-PAN) capable of complete separation of Xe from Kr in a single pass, allowing Kr to be captured downstream with no detectable Xe present.« less

Under the Off-Gas Sigma Team, Idaho National Laboratory (INL) and Pacific Northwest National Laboratoory (PNNL) have been able to study various sorbents for the separation of krypton (Kr) and xenon (Xe). PNNL has researched and prepared various metal-organic frameworks (MOFs) to use for the separation. Calcium–4,4’–sulfonyl dibenzoate (CaSDB), a high surface area MOF, was synthesized and sent to INL for deep bed testing. The MOF showed an acceptable saturation capacity, but a low breakthrough capacity; However, the recieved MOF was deemed as unusable in a flow system because of its powdery nature. In 2018, PNNL sent a sample of CaSDBmore » – MOF powder to INL with the goal to incorporate it into an engineered form that maintained adsorption properties comparable to the original MOF. It was anticipated that the engineered form of the sorbent would possess sufficient mechanical strength to be used in a column, and eliminate the dustiness of the raw material to improve handling and operability. An engineered from of CaSDB – MOF (CaSDB – EF1) was produced by incorporating the raw powder into a polyacrylonitrile (PAN) binder. The PAN binding material eliminated the dustiness of the raw MOF and provided a robust matrix that prevents damage from handling and use in a column. Xe adsorption testing of the sorbent revealed that it performs as well or better than previous CaSDB samples tested at INL, with an initial breakthrough capacity of 14.4 mmol/ kg at ambient temperature. Reducing the operating temperature to 253 K resulted in an increased breakthrough capacity of Xe.« less