Behaviour mechanisms and correlation between lead (Pb) and its isotope 210Pb in industrial residue as an indicator for waste characterization

PubMed ID: 27144415Total lead and 210Pb concentrations were determined in various ash fractions (collected from two of the world’s largest oil shale-fired power plants) by inductively coupled plasma mass-spectrometry (ICP-MS) and gamma spectrometry. Results show a clear increase in total lead (values up to 193 ppm in filter ashes) and 210Pb (values up to 148 Bq kg-1 in filter ashes) concentrations in the ash fractions from the furnace towards the filter ashes. A strong positive linear correlation (Pearson’s bivariate correlation remained between 0.86 and 0.99) was determined between total lead concentration (ppm) and 210Pb activity concentration (Bq kg-1) within all the boilers under observation. The constant concentration ratio between total lead and 210Pb remained around one (with minor exceptions), independent of the sampling location and the used combustion technology. The determined concentration ratio can be applicable as an indicative tool in waste material characterization. It also provides multiple additions to the general material characterization approach, by integrating radiological and elemental studies and providing an option to rapidly obtain initial indicative information about the residues. This in turn helps to generate the initial information to work out the next steps in waste material management. © 2016 Informa UK Limited, trading as Taylor & Francis Group.Citrus Research and Development Foundation EMP-45 National Science Foundation: 22/2011, OISE-9531011 Eesti Teadusagentuur: ETF9304 ESP1-7030-TR-11This work was supported by the EEA Financial Mechanism and Norwegian Financial Mechanism [grant number EMP-45]; Estonian Research Council award [grant number ETF9304]; CRDF Global and Estonian Science Foundation 2010 Energy Research Competition grant CRDF-ETF II, including CRDF [grant number ESP1-7030-TR-11] (National Science Foundation cooperative agreement OISE-9531011) and ETF award [22/2011]. -

Pb-210 and Po-210 atmospheric releases via fly ash from oil shale-fired power plants

PubMed ID: 28062225During high temperature processes in the furnace volatile and semi-volatile elements and radionuclides are partially emitted to the environment, depending on their chemical form in the original fuel, the technological set-up of the combustion system, and the prevailing combustion conditions. Two of the world's largest oil shale-fired power plants (PPs) have been operational in Estonia from the 1960s, during which time creation of significant environmental emissions and waste containing naturally occurring radionuclides has occurred. Pb-210 and210Po are considered natural radionuclides with the highest emission rates from PPs and possess elevated potential radiation exposure risks to humans and the environment. These radionuclides have the highest activity concentration values in fine ash fractions, especially in fractions remaining below 2.5 µm. To determine the activity concentrations of210Pb and210Po in the PPs' outlet, sampling was conducted from boilers operating on pulverized fuel (PF) technology with novel integrated desulphurization (NID) system and bag filters as well as with electrostatic precipitators (ESPs). The210Pb and210Po activity concentrations remained around 300 Bq kg-1for the NID system compared to 60–80 Bq kg-1in the ESP system. The dominant ash fraction in both systems was PM2.5, constituting over 50% of the fly ash mass collected from the outlet. The authors estimate that the total atmospherically emitted activity for the modernized PPs remains dominantly below 1% of the activity that is inserted via fuel. The implementation of higher efficiency purifications systems has significantly reduced the negative effect of these PPs. Based on annually emitted fly ash and boilers' working hours, the210Pb and210Po activity released relative to energy production were up to 68.3 kBq GWhel -1for210Pb and 64.6 kBq GWhel -1for210Po. These values are 1 to 2 orders of magnitude lower compared to the situation in the 1980s. These findings represent the first publicly available quantitative results estimating the210Po emissions from large oil shale-fired PPs. © 2016 Elsevier Lt

Development of a reference material for analysing naturally occurring radioactive material from the steel industry

Accurate measurement of naturally occurring radionuclides in blast furnace slag, a by-product of the steel industry, is required for compliance with building regulations where it is often used as an ingredient in cement. A matrix reference blast furnace slag material has been developed to support traceability in these measurements. Raw material provided by a commercial producer underwent stability and homogeneity testing, as well as characterisation of matrix constituents, to provide a final candidate reference material. The radionuclide content was then determined during a comparison exercise that included 23 laboratories from 14 countries. Participants determined the activity per unit mass for 226Ra, 232Th and 40K using a range of techniques. The consensus values obtained from the power-moderated mean of the reported participant results were used as indicative activity per unit mass values for the three radionuclides: A0(226Ra) = 106.3 (34) Bq·kg−1, A0(232Th) = 130.0 (48) Bq·kg−1 and A0(40K) = 161 (11) Bq·kg−1 (where the number in parentheses is the numerical value of the combined standard uncertainty referred to the corresponding last digits of the quoted result). This exercise helps to address the current shortage of NORM industry reference materials, putting in place infrastructure for production of further reference materials.[Display omitted]•Current availability of reference materials for naturally occurring radioactive material has been expanded upon.•A blast furnace slag reference material has been developed to support the steel industry and regulations regarding its use in building materials.•A comparison exercise of 23 laboratories was used to determine consensus values for the activity per unit mass of selected radionuclides.•Infrastructure has been built for future development of reference materials in support of naturally occurring radioactive materials