Selective ion exclusion from charged nanopores in track-etched membranes allows separation of ions with different charges or mobilities. This study examines pressure-driven transport of dissolved ions through track-etched membranes modified by adsorption of poly(styrene sulfonate) (PSS)/protonated poly(allylamine) (PAH) films. For nominal 30 nm pores modified with a single layer of PSS, Br(-)/SO4(2-) selectivities are ∼3.4 with SO4(2-) rejections around 85% due to selective electrostatic exclusion of the divalent anion from the negatively charged pore. Corresponding membranes containing an adsorbed PSS/PAH bilayer are positively charged and exhibit average K(+)/Mg(2+) selectivities >10 at 8 mM ionic strength, and Mg(2+) rejections are >97.5% at ionic strengths <5 mM. The high rejection of Mg(2+) compared to SO4(2-) likely results from both a smaller pore size after deposition of the PAH layer and higher surface charge because of Mg(2+) adsorption. Simultaneous modeling of K(+) and Mg(2+) rejections using the nonlinearized Poisson-Boltzmann equation gives an average modified pore diameter of 8.4 ± 2.1 nm, which does not vary significantly with ionic strength. This diameter is smaller than that calculated from hydraulic permeabilities and estimated pore densities, suggesting that narrow regions near the pore entrance control ion transport. In addition to simple electrostatic exclusion, streaming potentials lead to differing rejections of Br(-) and acetate in PSS/PAH-modified pores, and of Li(+) and Cs(+) in PSS-modified pores. For these cases, electrical migration of ions toward the feed solution results in higher rejection of the more mobile ion.

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The Environmental Restoration Contractor at the Hanford Site is tasked with removing auxiliary reactor structures and leaving the remaining concrete structure surrounding each reactor core. This is referred to as Interim Safe Storage. Part of placing the F Reactor into Interim Safe Storage is the demolition of the fuel storage basin, which was deactivated in 1970 by placing debris material into the basin prior to back filling with soil. Besides the debris material (wooden floor decking, handrails, and monorail pieces), the fuel storage basin contents included the possibility of spent nuclear fuel, fuel buckets, fuel spacers, process tubes, and tongs. Demolition of the fuel storage basin offered many unique radiological control challenges and innovative approaches to demolition. This paper describes how the total effective dose equivalent and contamination were controlled, how the use of a remote operated excavator was employed to remove high-dose-rate material, and how wireless technology was used to monitor changing radiological conditions.