Review of FFTF and CRBRP control rod systems designs

Abstract

capacity. Despite its use on several existing reactors, the technology for the ball screw mechanism, with its required separate scram latch was not as well developed in the U.S.A. as the roller nut type. In addition, the maintenance functions are net as straightforward with the existing ball screw type drive. The modifications required to improve the maintenance functions as well as to meet the FFTF space constraints would have resulted in an essentially new and untested design. Therefore, the roller nut drive mechanism was the logical choice, based on its operational capabilities and well developed technology.

How Does Scale of Implementation Impact the Environmental Sustainability of Wastewater Treatment Integrated with Resource Recovery?

“…Similar findings were reported in United States studies investigating the impact of scale on the environmental sustainability of WWTPs integrated with resource recovery. ,, Whereas these studies consider the fertilizers avoided through nutrient recycling from biosolids, none considered fertilizers avoided from nutrients recovered through water reuse. Additionally, one of these studies considered the environmental impacts avoided by replacing river water with reclaimed water; however, the impacts avoided by replacing potable water with reclaimed water merits further investigation .…”

“…Similar findings were reported in United States studies investigating the impact of scale on the environmental sustainability of WWTPs integrated with resource recovery. ,, Whereas these studies consider the fertilizers avoided through nutrient recycling from biosolids, none considered fertilizers avoided from nutrients recovered through water reuse. Additionally, one of these studies considered the environmental impacts avoided by replacing river water with reclaimed water; however, the impacts avoided by replacing potable water with reclaimed water merits further investigation . The omission of environmental impacts mitigated by replacing potable water with reclaimed water could lead to misleading results when considering reuse in regions where potable water is used for irrigation and cannot be readily replaced with other less energy-intensive sources of nonpotable irrigation water (e.g., untreated surface water, groundwater).…”

“…Anaerobic treatment from the household septic tank has the highest contribution to CH 4 emissions (0.36 kg CO 2 eq/m 3 ), whereas community and city scales methane emissions are negligible. Similarly, another study found that CH 4 contributions were higher for septic systems compared to larger WWTPs. Another study found that measured CH 4 emissions from septic tanks can be approximately 2 times less than the theoretical estimates; however, this does not impact the overall carbon footprint trends found in this research.…”

“…Both local (e.g., nutrient management to protect local streams) and global (e.g., energy efficiency to reduce carbon footprint) concerns have led to a growing interest in scale’s influence on the environmental sustainability of WWTPs. Previous studies have used life cycle assessment (LCA) to investigate the impact of scale on the environmental sustainability of WWTPs in Sweden, the United Kingdom, and the United States; however, most of these studies do not consider holistically integrated resource recovery including water reuse, energy recovery, and nutrient recycling. − Similar to a comprehensive review of LCA’s applied to wastewater systems, these studies vary in system boundary, environmental impact categories, and scope, making it difficult to compare results from different studies. Despite these difficulties, several European studies investigating source separation schemes and sludge management options highlight the benefits to centralization due to economies of scale. − …”

Misuse Detection for a Generalized SFR Test Reactor

“…The Westinghouse PWR control rod drive mechanism uses a system of magnetic coils, called a "magnetic jack" to locate the control rod in 5/8 inch steps [9]. The FFTF control rod steps were on the order of 0.025 inch [10]. For smaller reactors, it is possible to design control rod steps with much finer position/indication.…”