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Recycling electronic waste (WEEE) is a fundamental aspect of the circular economy. To develop technology and assess its economic aspects, the composition characterization of the waste items is crucial. Neutron-based analytical techniques, such as the INAA, in-beam NAA, and PGAA, are applicable to measure the elemental composition of WEEE. These techniques are bulk representative and offer simultaneous determination of the relevant elements without sample dissolution. This study explores the suitability of neutron-based elemental analysis methods for measuring common WEEE items, e.g., printed circuit boards and integrated circuits. Matrix effects mostly related to the thermal neutron self-shielding, were identified and successfully corrected, ensuring accurate mass fraction measurements. [ABSTRACT FROM AUTHOR]

The Santa Vitória Chalcolithic site (southern Portugal) prompts several questions related to the provenance and production technology of artefacts. Archaeological ceramics from two sections of Ditch 1 of the Santa Vitória site were studied by neutron activation analysis and X-ray diffraction for the first time, with the main goal of contributing to the contextualization of the artefacts and better understanding their production processes/technologies and the provenance of raw materials. The results point to a local production of ceramics, since their mineral phases reflect the geological contexts around the archaeological site. The mineralogical assemblage indicates a firing temperature below 850 °C. Iron is the better discriminator of ceramics from both sections, which could be related to the addition of different proportions of temper grains during the ceramics' production. Although trace elements do not serve as discriminating geochemical indicators for the analyzed samples, they do imply a slightly higher heterogeneity in the composition of the ceramic paste from section 2. The negative Eu anomaly found in two samples is in accordance with the lower contents of Na2O, related to plagioclase weathering. Detailed studies on ceramics and potential raw materials are foreseen to assist in discussing the role of this Chalcolithic archaeological site at a regional level. [ABSTRACT FROM AUTHOR]

Significant gravel mines, representative of four regions of Hungary (northeast, central, northwest, and southwest) were systematically sampled to characterize their sand and pebbles as potential constituents of nuclear-grade concrete. The samples were analysed for their elemental compositions as a function of the mining locality and grain size, using two complementary neutron-based analytical techniques, prompt gamma activation analysis (PGAA) and neutron activation analysis (NAA). The combined analysis resulted in reliable mass fractions for over thirty elements that could be used to assess the radiation shielding and activation properties of the resulting concrete, essential in nuclear applications, by means of computer simulations. The studied aggregates are proven to be appropriate constituents for biological shielding at radiological centres, NPPs, and at nuclear research installations, even in mixed neutron/gamma radiation fields. The elemental compositions also revealed geochemical differences between the sedimentologically different regions. [ABSTRACT FROM AUTHOR]

The present work investigates the hydration heat of different cement composites by means of conduction calorimetry to optimize the composition of binder in the design of heavyweight concrete as biological shielding. For this purpose, Portland cement CEM I 42.5 R was replaced by a different portion of supplementary cementitious materials (blast furnace slag, metakaolin, silica fume/limestone) at 75%, 65%, 60%, 55%, and 50% levels to obtain low hydration heat lower than 250 j g−1. All ingredients were analyzed by energy dispersive X-ray fluorescence (EDXRF) and nuclear activation analysis (NAA) to assess the content of major elements and isotopes. A mixture of two high-density aggregates (barite and magnetite) was used to prepare three heavyweights concretes with compressive strength exceeding 45 MPa and bulk density ranging between 3400 and 3500 kg m−3. After a short period of volume expansion (up to 4 h), a slight shrinkage (max. 0.3°/°°) has been observed. Also, thermophysical properties (thermal conductivity, volumetric specific heat, thermal diffusivity) and other properties were determined. The results showed that aggregate content and not binder is the main factor influencing the engineering properties of heavyweight concretes. [ABSTRACT FROM AUTHOR]

The design of concrete for radiation shielding structures is principally based on the selection of materials of adequate elemental composition and mix proportioning to achieve the long-term durability in nuclear environment. Concrete elements may become radioactive through exposure to neutron radiation from the nuclear reactor. A selection of constituent materials of greatly reduced content of long-lived residual radioisotopes would reduce the volume of low-level waste during plant decommissioning. The objective of this investigation is an assessment of trace elements with a large activation cross section in concrete constituents and simultaneous evaluation of susceptibility of concrete to detrimental alkali-silica reaction. Two isotopes 60Co and 152Eu were chosen as the dominant long-lived residual radioisotopes and evaluated using neutron activation analysis. The influence of selected mineral aggregates on the expansion due to alkali-silica reaction was tested. The content of 60Co and 152Eu activated by neutron radiation in fine and coarse aggregates, as well as in four types of Portland cement, is presented and discussed in respect to the chemical composition and rock origin. Conflicting results were obtained for quartzite coarse aggregate and siliceous river sand that, despite a low content, 60Co and 152Eu exhibited a high susceptibility to alkali-silica reaction in Portland cement concrete. The obtained results facilitate a multicriteria selection of constituents for radiation-shielding concrete. [ABSTRACT FROM AUTHOR]