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DNFSB spots possible bottleneck in Hanford’s waste vitrification
Workers change out spent 27,000-pound TSCR filter columns and place them on a nearby storage pad during a planned outage in 2023. (Photo: DOE)
While the Department of Energy recently celebrated the beginning of hot commissioning of the Hanford Site’s Waste Treatment and Immobilization Plant (WTP), which has begun immobilizing the site’s radioactive tank waste in glass through vitrification, the Defense Nuclear Facilities Safety Board has reported a possible bottleneck in waste processing. According to the DNFSB, unless current systems run efficiently, the issue could result in the interruption of operations at the WTP’s Low-Activity Waste Facility, where waste vitrification takes place.
During operations, the LAW Facility will process an average of 5,300 gallons of tank waste per day, according to Bechtel, the contractor leading design, construction, and commissioning of the WTP. That waste is piped to the facility after being treated by Hanford’s Tanks Side Cesium Removal (TSCR) system, which filters undissolved solid material and removes cesium from liquid waste.
According to a November 7 activity report by the DNFSB, the TSCR system may not be able to produce waste feed fast enough to keep up with the LAW Facility’s vitrification rate.
Nadish Saini, Igor A. Bolotnov
Nuclear Technology | Volume 208 | Number 8 | August 2022 | Pages 1244-1265
Technical Paper | doi.org/10.1080/00295450.2021.1974279
Articles are hosted by Taylor and Francis Online.
Spacer grids and mixing vanes exhibit a significant role in the thermal hydraulics of pressurized water reactors (PWRs), especially in the post loss-of-coolant accident regimes. A detailed analysis of the contrasting upstream and downstream turbulent flow features is of great importance to both system codes and computational fluid dynamics (CFD)–Reynolds-averaged Navier–Stokes (RANS) modeling. Further, with the advent of supercomputing resources and machine learning research, a data-driven approach to turbulence modeling is gaining popularity. However, owing to the complexities associated with large-scale, high-fidelity data collection capabilities, the application of machine learning–based turbulence models has been limited to simple geometries. In this work, using a highly scalable CFD code PHASTA, we have collected data from direct numerical simulations of a PWR subchannel with high spatial and temporal resolution. From the collected data we extract key turbulent flow features, including mean velocities and Reynolds stresses that highlight the effects of spacer grids and mixing vanes on downstream turbulence in a typical PWR subchannel. An invariant analysis of the anisotropic stress tensor is also presented, which further elucidates their effect on the nature of turbulence in the immediate upstream and downstream vicinity. The high-resolution data from the simulations are archived and intended for the development of data-driven RANS closure models that are capable of capturing the evolution of anisotropy in PWR subchannels.