Measurement of liquid scintillation sources of (210)Pb obtained from (222)Rn decay.
Liquid scintillation samples were filled with (222)Rn and the activity was measured with good precision after reaching the secular equilibrium with the progeny (218)Po, (214)Pb, (214)Bi and (214)Po. After decay of most of (222)Rn activity, the samples contain (210)Pb and progeny. The activities of (210)Pb and progeny can be calculated as a function of time using the initial (222)Rn activity. The samples were measured in a TDCR counter and the experimentally determined counting efficiencies are in accordance with previously published results.
210Pb/210bi detection in waters by cherenkov counting – perspectives and new possibilities
Abstract The measurement of 210Pb activity concentration via its product 210Bi, high-energy beta emitter capable of producing Cherenkov radiation in waters, by liquid scintillation counter Quantulus 1220 has been explored. Without the chemical pre-treatment, the detection limits have been evaluated and possibilities to further decrease M D A value have been considered. Prolonging the counting time coupled to the sample's evaporation prior to counting can enable the achievement of the detection limits below maximal permitted levels recommended by the international legislation. The impact of sodium salicylate addition to the counting vials on the detection efficiency and consequently M D A value has been tested. Sodium salicylate application is associated with the certain complications during sample preparation, here we propose salicylate-based ionic liquids instead. We present an innovative experiment that explores the influence of the addition of a synthesized 2-hydroxypropan-1-amminium salicylate to the counting vials in order to decrease M D A parameter. Furthermore, the interference with 226Ra Cherenkov spectra was assessed and the possibility to evaluate its contribution to 210Pb/210Bi spectra has been proposed. The potential of 210Pb screening in the samples without the chemical isolation of 210Pb has not been thoroughly considered in the literature so far. 210Pb screening of a few spiked samples and real samples collected in the vicinity of mine was carried out, thus the obtained results demonstrate the method's evaluation and set its limitations.
Techno-economic analysis of chemical looping combustion with humid air turbine power cycle
Abstract Power generation from fossil fuel-fired power plant is the largest single source of CO2 emission. CO2 emission contributes to climate change. On the other hand, renewable energy is hindered by complex constraints in dealing with large scale application and high price. Power generation from fossil fuels with CO2 capture is therefore necessary to meet the increasing energy demand, and reduce the emission of CO2. This paper presents a process simulation and economic analysis of the chemical looping combustion (CLC) integrated with humid air turbine (HAT) cycle for natural gas-fired power plant with CO2 capture. The study shows that the CLC–HAT including CO2 capture has a thermal efficiency of 57% at oxidizing temperature of 1200 °C and reducer inlet temperature of 530 °C. The economic evaluation shows that the 50 MWth plant with a projected lifetime of 30 years will have a payback period of 7 years and 6 years for conventional HAT and CLC–HAT cycles respectively. The analysis indicates that CLC–HAT process has a high potential to be commercialised.