Managing Beryllium in Nuclear Facility Applications

High-Temperature Intrinsic Defect Chemistry of Li8PbO6 Ceramic Breeding Material

Understanding the intrinsic defect chemistry of tritium breeder materials proposed for use in future fusion reactors is imperative, as certain defects may act as traps leading to retention of tritium in the ceramic matrix. In this paper, we use combined density functional theory simulations with simple thermodynamics to explore the intrinsic defect chemistry of octalithium plumbate (Li8PbO6) as a function of both temperature and oxygen partial pressure. Importantly, we consider vibrational contributions to the energies of the reference states used in the calculations of the defect formation energies. Our results indicate that including these temperature effects can modify the predicted defect chemistry for materials at a high temperature. For Li8PbO6, the defect chemistry is predicted to be dominated by the VLi-1 defect, which will likely act as a trap for tritium. The charge compensating mechanism is predicted to change as a function of the conditions, with the Lii+1 interstitial defect providing compensation at low temperatures and the VO2+ vacancy defect occurring close to the Li2O saturation limit.

Role of beryllium in the environment: Insights from specific sorption and precipitation studies under different conditions

In this study, we examined factors influencing the environmental behaviour of Be, specifically considering soils collected from a legacy radioactive waste disposal site near Sydney (Australia). The precipitation study showed the formation of Be(OH)₂ (amorphous) from ICP standard solution, but a mixture of Be(OH)₂ (alpha), Be(OH)₂ (beta) and ternary Na/S-Be (ΙΙ)-OH(s) solid phase were formed from BeSO₄ solutions. The precipitation of Be started at relatively lower pH at higher concentrations than at the lower Be concentration as indicated by both laboratory data and simulation. Across the pH range, the Be sorption curve was divided into three phases, these being pH 3-6, pH 6-10, and pH > 10, within which sorption of Be with soil was 9-97%, 90-97%, and 66-90%, respectively. Beryllium solubility was limited at pH > 7, but a sorption study with soil showed chemisorption under both acidic and alkaline pH (pH 5.5 and 8) conditions, which was confirmed by FTIR and XPS analysis. At pH 5.5 (specifically relevant to the study site), sorption of Be was 72-95%, in which 77% and 46% Be was respectively sorbed by separated fulvic and humic acid fractions. The irreversible chemisorption mechanism was controlled by SOM at higher pH, and by metal oxyhydroxides at lower pH. Both organic and inorganic components synergistically influence the specific chemisorption of Be at the intermediate pH 5.5 of field soil.

Beryllium in contaminated soils: Implication of beryllium bioaccessibility by different exposure pathways

Inhalation exposure and beryllium (Be) toxicity are well-known, but research on bioaccessibility from soils via different exposure pathways is limited. This study examined soils from a legacy radioactive waste disposal site using in vitro ingestion (Solubility Bioaccessibility Research Consortium [SBRC], physiologically based extraction test [PBET], in vitro gastrointestinal [IVG]), inhalation (simulated epithelial lung fluid [SELF]) and dynamic two-stage bioaccessibility (TBAc) methods, as well as 0.43 M HNO₃ extraction. The results showed, 70 ± 4.8%, 56 ± 16.8% and 58 ± 5.7% of total Be were extracted (gastric phase [GP] + intestinal phase [IP]) in the SBRC, PBET, and IVG methods, respectively. Similar bioaccessibility of Be (~18%) in PBET-IP and SELF was due to chelating agents in the extractant. Moreover, TBAc-IP showed higher extraction (20.8 ± 2.0%) in comparison with the single-phase (SBRC-IP) result (4.8 ± 0.23%), suggesting increased Be bioaccessibility and toxicity in the gastrointestinal tract when the contamination derives from the inhalation route. The results suggested Be bioaccessibility depends on solution pH; time of extraction; soil reactive fractions (organic-inorganic); particle size, and the presence of chelating agents in the fluid. This study has significance for understanding Be bioaccessibility via different exposure routes and the application of risk-based management of Be-contaminated sites.

Determination of the long-lived 10Be in construction materials of nuclear power plants using photoactivation method

The problem of handling nuclear power plant irradiated structural materials holds one of the central places in the nuclear power industry. High toxic ¹⁰Be with a half-life of T_1/2 = 1.6 × 10⁶ years is discovered in NPP structural materials after reactor operating. ¹⁰Be decays through only electrons' emission. Pure beta emitters are extremely difficult to determine in irradiated structural materials and radioactive waste. We proposed a photoactivation approach for determining the ¹⁰Be activity in NPP samples. The proposed method involves determining ⁹Be and ¹⁰B concentrations and subsequent recalculation of ¹⁰Be activity formed in ⁹Be(n, γ)¹⁰Be and ¹⁰B(n, p)¹⁰Be reactions. The amount of ⁹Be and ¹⁰B is determined by samples' photoactivation using an electron accelerator and ⁹Be(γ, 2n)⁷Be-, ¹⁰B(γ, p2n)⁷Be-reactions. These reactions' experimental yields were measured for 20, 40, and 55 MeV boundary energies of the bremsstrahlung beam. The proposed technique was tested on samples of ChNPP 2^nd unit irradiated structural materials. The technique's calculated error is about 15-20%; the sensitivity is 1 Bq × g^-1.