Ion beam techniques for nuclear waste management (original) (raw)
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LABEC, the INFN ion beam laboratory of nuclear techniques for environment and cultural heritage
The European Physical Journal Plus, 2021
The LABEC laboratory, the INFN ion beam laboratory of nuclear techniques for environment and cultural heritage, located in the Scientific and Technological Campus of the University of Florence in Sesto Fiorentino, started its operational activities in 2004, after INFN decided in 2001 to provide our applied nuclear physics group with a large laboratory dedicated to applications of accelerator-related analytical techniques, based on a new 3 MV Tandetron accelerator. The new accelerator greatly improved the performance of existing Ion Beam Analysis (IBA) applications (for which we were using since the 1980s an old single-ended Van de Graaff accelerator) and in addition allowed to start a novel activity of Accelerator Mass Spectrometry (AMS), in particular for 14C dating. Switching between IBA and AMS operation became very easy and fast, which allowed us high flexibility in programming the activities, mainly focused on studies of cultural heritage and atmospheric aerosol composition, bu...
Ion beam analysis of radioactive samples
Nuclear Instruments & Methods in Physics Research Section B-Beam Interactions With Materials and Atoms, 2009
The nuclear microprobe facility of the Pierre Süe Laboratory is fitted with two microbeam lines. One is dedicated to non-active samples. The other one, located in a controlled shielded area, offers the unique feature of being devoted to radioactive samples. Operational since 1998, it is strongly linked to nuclear research programs and has been dimensioned to accept radioactive but non-contaminant radioactive samples, including small quantities of UOX or MOX irradiated fuel. The samples, transported in a shipping cask, are unloaded and handled in hot cells with slaved arms.
14C in Radioactive Waste for Decommissioning of the Ignalina Nuclear Power Plant
Radiocarbon, 2013
Radiocarbon is one of the most significant radionuclides affecting the safety margins of near-surface repositories for the disposal of low-and intermediate-level, short-lived radioactive waste, arising from the operation and decommissioning of nuclear power plants (NPPs). One of the goals of the present study was to characterize radioactive waste from Ignalina NPP (Lithuania) (storage tanks TW18B01 and TW11B03) from the spent ion-exchange resins/perlite stream to determine the 14 C-specific activity of inorganic and organic carbon compounds. The approach applied is based on classical radiochemical separation methods, including acid-stripping techniques and wet oxidation with subsequent catalytic combustion. The suitability of the method for 14 C-specific activity determination in ion-exchange resin samples with a minimum detectable activity of 0.5 Bq/g by liquid scintillation counting (LSC) was demonstrated. The extraction efficiency of inorganic and organic carbon compounds based on model samples with known 14 C activity was estimated. The fraction of 14 C associated with organic compounds ranged from 42% to 63% for storage tank TW18B01 and from 30% to 63% for storage tank TW11B03. The specific activity of inorganic 14 C was estimated as 12.6 Bq/g with a relative standard deviation (RSD) of 29% for storage tank TW18B01, and 177.5 Bq/g with a RSD of 35% for storage tank TW11B03. Based on volume and density data, the total 14 C activity for radioactive waste stored in tanks TW18B01 and TW11B03 was estimated as 3.59E + 10 Bq (±32%) and 4.15E + 11 Bq (±28%), respectively.
14C selective extraction from French graphite nuclear waste by CO2 gasification
Progress in Nuclear Energy, 2018
The decommissioning of French gas-cooled nuclear reactors, all stopped since 1994, will generate 23,000 tons of nuclear waste containing 14 C among other radionuclides. This work aims at presenting and testing a selective extraction treatment of this radionuclide from graphite waste by carbon dioxide gasification. In previous works, we highlighted that graphite turns into a heterogeneously degraded carbon with neutron irradiation and 14 C could preferentially be concentrated in the most degraded zones. Moreover, these last react selectively with CO 2 that would allow the 14 C extraction from graphite waste. The results on graphite waste are promising with the quarter of 14 C inventory extracted for a relative weight loss of few percent. Up to 68% of 14 C inventory was extracted, but with a more important mass consumption. Thus, the potential of this selective 14 C extraction would allow imagining alternative scenarios for graphite waste management.
14C leaching and speciation studies on Irradiated graphite from vandellós I Nuclear Power Plant
2018
The understanding of the 14C behavior in waste packages could lead, in the Spanish context, to a revision of the management strategies for radioactive waste and a revaluation of the near surface repository devoted to the disposal of waste containing this radionuclide in high concentrations. To achieve this objective, and in the context of the EU project Carbon-14 Source Term (CAST), the authors of the work presented in this paper have performed leaching experiments with irradiated graphite considering two different scenarios. One, in which the leaching solution simulates some of the expected conditions in a repository where a granite/bentonite mixture has been used as backfill material, and the other, using deionized water as a high efficiency chemical removal agent and for comparison purposes. The analytical approach to measure the release rate and speciation of 14C from irradiated graphite samples in the aqueous and gaseous phase is also described. The main results obtained shows ...
PloS one, 2016
Pile Grade A graphite was used as a moderator and reflector material in the first generation of UK Magnox nuclear power reactors. As all of these reactors are now shut down there is a need to examine the concentration and distribution of long lived radioisotopes, such as 14C, to aid in understanding their behaviour in a geological disposal facility. A selection of irradiated graphite samples from Oldbury reactor one were examined where it was observed that Raman spectroscopy can distinguish between underlying graphite and a surface deposit found on exposed channel wall surfaces. The concentration of 14C in this deposit was examined by sequentially oxidising the graphite samples in air at low temperatures (450°C and 600°C) to remove the deposit and then the underlying graphite. The gases produced were captured in a series of bubbler solutions that were analysed using liquid scintillation counting. It was observed that the surface deposit was relatively enriched with 14C, with samples...
The 14C AMS facility at LABEC, Florence
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2007
The main facility of the new INFN laboratory in Florence (LABEC, LAboratorio di tecniche nucleari per i BEni Culturali) is a 3 MV Tandetron accelerator, manufactured by High Voltage Engineering Europe, used for both Accelerator Mass Spectrometry and Ion Beam Analysis (IBA) measurements. The AMS beam line is equipped with a 59-sample sputter ion source and a sequential injector-on the low energy side-and a spectrometer composed of a 115°analysing magnet and a 65°electrostatic analyser-on the high energy side. A sample preparation laboratory has been installed for radiocarbon measurements. Combustion of pre-treated organic samples is performed using an elemental analyser; four parallel graphitisation reactors are available for CO 2 reduction. In this paper, the performance of the whole system is presented: 14 C values of chemistry blanks correspond to radiocarbon ages in the order of 50,000 years BP; measurements of 14 C concentration in different standard reference materials demonstrate good accuracy.
Radioprotection, 2009
A high temperature combustion method was used to analyze the 14 C and 3 H activities in graphite and the dose assessment was carried out to determine the clearance in the conservative way. By this method, the 3 H and 14 C were simultaneously trapped in the nitric acid and carbosorb, respectively. Accordingly, the sample preparation time for the measurement was reduced to the half. The combustion temperature was more than 800 degrees in centigrade for obtaining total tritium and 14 C in the sample. The combustion ratio was about 99% on the graphite sample with the weight of 0.1 g. Minimum detectable activity was 0.05 Bq/g for the 14 C and 0.15 Bq/g for the 3 H at the same background counting time. The recoveries from the combustion furnace were around 100% and 90% in 14 C and 3 H, respectively. The radioactivity were 2, 530 ∼ 3,160 Bq/g in 14 C and 1, 700 ∼2,040 Bq/g in 3 H at this experiment. The experimental uncertainty was less than 6% in both radionuclides where the furnace recovery was dominant factor. An individual effective dose from beta and gamma radionuclides was estimated by consideration of the scenario of inhalation, ingestion and external exposure. 60 Co, the radioactivity of which was measured by using HPGe detector, had a predominant effect in estimating the effective dose. The estimation showed that the graphite wastes from the dismantled research reactor should be disposed of as a low level radioactive waste rather than clearance.
Mineralogical Magazine, 2015
Large quantities of irradiated graphite will arise from the decommissioning of the UK's Magnox power stations. Irradiated graphite contains 14C as well as other longer lived radionuclides (e.g. 36Cl). The potential use of magnetic sector secondary ion mass spectrometry (MS-SIMS) to examine the distribution of the 14C within trepanned graphite samples from a Magnox nuclear power station has been investigated. This work indicates that the methodology proposed has the potential to be used to analyse irradiated graphite samples with preliminary results highlighting a possible 14C enrichment in the carbonaceous deposit found on a channel wall sample. 14C concentrations in samples without this deposit were below the limits of detection of the instrument. The methodology used for these determinations ensured that possible mass interferences between 14C species and oxygen-bearing or nitrogen-bearing species were eliminated from the analysis. Future work will utilize the methodology prop...