A nuclear reaction-induced dynamic therapy, denoted as nucleodynamic therapy (NDT), has been invented that triggers immunogenic cell death and successfully treats metastatic tumors due to its unexpected abscopal effect. Gadolinium neutron capture therapy (GdNCT) is binary radiotherapy based on a localized nuclear reaction that produces high-energy radiations (e.g., Auger electrons, γ-rays, etc.) in cancer cells when ¹⁵⁷Gd is irradiated with thermal neutrons. Yet, its clinical application has been postponed due to the poor ability of Auger electrons and γ-rays to kill cells. Here, we engineered a ¹⁵⁷Gd-porphyrin framework that synergizes GdNCT and dynamic therapy to efficiently produce both •OH and immunogenic ¹O₂ in cancer cells, thereby provoking a strong antitumor immune response. This study unveils the fact and mechanism that NDT heats tumor immunity. Another unexpected finding is that the Auger electron can be the most effective energy-transfer medium for radiation-induced activation of nanomedicines because its nanoscale trajectory perfectly matches the size of nanomaterials. In mouse tumor models, NDT causes nearly complete regression of both primary and distant tumor grafts. Thus, this ¹⁵⁷Gd-porphyrin framework radioenhancer endows GdNCT with the exotic function of triggering dynamic therapy; its application may expand in clinics as a new radiotherapy modality that utilizes GdNCT to provoke whole-body antitumor immune response for treating metastases, which are responsible for 90% of all cancer deaths. 

Selenium (Se) is a key mobile fission product in the geological disposal of nuclear waste. It is necessary to analyze the reductive deposition behavior of iron-based materials to Se(IV) and Se(VI) in groundwater. In the present work, the corrosion behavior of 304 stainless steel in simulated groundwater (SG) and the effects of corrosion products on the dissolution of Se were investigated by electrochemical and immersion tests. Experimental results revealed that passivation films formed on 304 stainless-steel samples were destroyed by polarization measurements, forming corrosion products consisting of Fe(II) compounds, such as Fe₃O₄ and FeO. Corrosion products deposited on the surface of steel samples previously treated by polarization measurements in SG + CaCl₂/Na₂CO₃/Na₂SiO₃ solutions effectively reduced soluble Se(IV) and Se(VI) during immersion tests, depositing FeSe₂ on sample surfaces.

Gadolinium neutron capture therapy (G d N C T) is an innovative treatment that exert damage on tumor cells based on the capture reaction between thermal neutron and gadolinium. In comparison with other types of neutron capture therapy(NCT), gadolinium has the highest thermal capture cross section of any natural elements. Gadolinium-based agents are widely used in magnetic resonance imaging(MRI) as contrast agents. The improvements of multiple gadolinium-based agents have been applied to enhance therapeutic efficacy of GdNCT. In this review, principles of gadolinium neutron capture therapy were studied and diverse strategies to improve therapeutic efficacy of gadolinium-based agents were summarized. Giving a perspective on GdNCT to prompt its clinical use.

As a typical material of the insert in high-level radioactive waste (HLW) geological disposal canisters, iron-based materials will directly contact with groundwater after the failure of a metallic canister, acting as a chemical barrier to prevent HLW leaking into groundwater. In this paper, anoxic groundwater was simulated by mixing 10 mM NaCl and 2 mM NaHCO₃ purged by Ar gas (containing 0.3% CO₂) with different added ions (Ca²⁺, CO₃²⁻ and SiO₃²⁻) and operation temperatures (25, 40 and 60 °C). An electrochemical measurement, immersion tests and surface characterization were carried out to study the corrosion behavior of pure iron in the simulated groundwater. The effects of Ca²⁺ on the corrosion behavior of iron is negligible, however, Cl⁻ plays an important role in accelerating the corrosion activity with the increased concentration and temperature. With increased concentrations of CO₃²⁻ and SiO₃²⁻, the corrosion resistance of iron is largely improved, which is attributed to the formation of a uniform passivation film. The independent effects of temperature on the corrosion behavior of iron are resulted from the repeated passivation–dissolution processes in the formation of the passivation film, resulting from the synergistic effects of CO₃²⁻/SiO₃²⁻ and Cl⁻. The formation of ferric silicate is dominant in the passivation film with the addition of SiO₃²⁻, which effectively protects the iron surface from corrosion.

Dense oxide dispersion strengthened (ODS) 316 L steels with different amount of Y2O3 additions were successfully fabricated by selective laser melting (SLM) even though part of the added Y2O3 got lost during the process. The microstructure was characterized in details and the mechanical properties were tested at room temperature, 250 degrees C and 400 degrees C, respectively. The effect of the scanning speed on agglomeration of nanoparticles during SLM process was discussed. Superior properties, e.g., yield strength of 574 MPa and elongation of 91%, were achieved at room temperature in SLM ODS 316 L with additional 1% of Y2O3. At elevated temperatures, the strength kept high but the elongations dropped dramatically. It was observed that nano-voids nucleated throughout the whole gauge section at the sites where nanoinclusions located. The growth and coalescence of these voids were suppressed by the formation of an element segregation network before necking, which relieved local stress concentration and thus delayed necking. This unusual necking behavior was studied and compared to the previous theory. It appeared that the strong convection presented in the melt pool can evenly redistribute the short-time milled coarse Y2O3 precursor powder during SLM process. These findings can not only solve the problems encountered during the fabrication of ODS components but also replenish the strengthening mechanism of SLM 316 L thus pave a way for further improving of mechanical properties.

A feasibility study was performed to fabricate ITER In-Vessel components by one of the metal additivemanufacturing methods, Electron Beam Melting®(EBM®). Solid specimens of SS316L with 99.8% relativedensity were prepared from gas atomized precursor powder granules. After the EBM®process the phaseremains as austenite and the composition has practically not been changed. The RCC-MR code used fornuclear pressure vessels provides guidelines for this study and tensile tests and Charpy-V tests werecarried out at 22C (RT) and 250C (ET). This work provides thefirst set of mechanical and micro-structure data of EBM®SS316L for nuclear fusion applications. The mechanical testing shows that theyield strength, ductility and toughness are well above the acceptance criteria and only the ultimatetensile strength of EBM®SS316L is below the RCC-MR code. Microstructure characterizations reveal thepresence of hierarchical structures consisting of solidified melt pools, columnar grains and irregularshaped sub-grains. Lots of precipitates enriched in Cr and Mo are observed at columnar grain boundarieswhile no sign of element segregation is shown at the sub-grain boundaries. Such a unique microstructureforms during a non-equilibrium process, comprising rapid solidification and a gradient‘annealing’process due to anisotropic thermalflow of accumulated heat inside the powder granule matrix. Relationsbetween process parameters, specimen geometry (total building time) and sub-grain structure are dis-cussed. Defects are formed mainly due to the large layer thickness (100mmÞwhich generates insufficientbonding between a few of the adjacently formed melt pools during the process. Further studies shouldfocus on adjusting layer thickness to improve the strength of EBM®SS316L and optimizing total buildingtime.

Fabrication of ITER First Wall (FW) Panel parts by two additive manufacturing (AM) technologies, selective laser melting (SEM) and electron beam melting (EBM), was supported by Fusion for Energy (F4E). For the first time, AM is applied to manufacture ITER In-Vessel parts with complex design. Fully dense SS316L was prepared by both SLM and EBM after developing optimized laser/electron beam parameters. Characterizations on the density, magnetic permeability, microstructure, defects and inclusions were carried out. Tensile properties, Charpy-impact properties and fatigue properties of SLM and EBM SS316L were also compared. ITER FW Panel parts were successfully fabricated by both SLM and EBM in a onestep building process. The SLM part has smoother surface, better size accuracy while the EBM part takes much less time to build. Issues with removing support structures might be solved by slightly changing the design of the internal cooling system. Further investigation of the influence of neutron irradiation on materials properties between the two AM technologies is needed.

Reductive precipitation of the radiotoxic nuclide Np-237 from nuclear waste on the surface of iron canister material at simulated deep repository conditions was investigated. Pristine polished as well as pre corroded iron specimens were interacted in a deoxygenated solution containing 10-100 mu M Np(V), with 10 mM NaCl and 2 mM NaHCO3 as background electrolytes. The reactivity of each of the two different systems was investigated by analyzing the temporal evolution of the Np concentration in the reservoir. It was observed that pre-oxidized iron specimen with a 40 tm Fe3O4 corrosion layer are considerably more reactive regarding the reduction and immobilization of aqueous Np(V) as compared to pristine polished FeM surfaces. Np-237 immobilized by the reactive iron surfaces was characterized by scanning electron microscopy as well as synchrotron-based micro-X-ray fluorescence and X-ray absorption spectroscopy. At the end of experiments, a 5-8 tm thick Np-rich layer was observed to be formed ontop of the Fe3O4 corrosion layer on the iron specimen. The findings from this work are significant in the context of performance assessments of deep geologic repositories using iron as high level radioactive waste (HLW) canister material and are of relevance regarding removing pollutants from contaminated soil or groundwater aquifer systems.

With selective laser melting the potential to manufacture a wide variety of geometries from different materials has presented itself. Interest in this technology keeps growing every year, and with that growth a deeper understanding of the process and resulting materials is urgently needed. In this paper we present a short overview of the structural elements that appear during selective laser melting, and explain how to tailor them to achieve specific structures and material properties. Melt-pools, texture and grains, subgrain cells, and inclusions are the elements discussed herein, and tailoring of these elements can have effects on density, and corrosion resistance, as well as mechanical properties in general.

A feasibility study was performed to fabricate ITER In-Vessel components by Selective Laser Melting (SLM) supported by Fusion for Energy (F4E). Almost fully dense 316L stainless steel (SS316L) components were prepared from gas-atomized powder and with optimized SLM processing parameters. Tensile tests and Charpy-V tests were carried out at 22 degrees C and 250 degrees C and the results showed that SLM SS316L fulfill the RCC-MR code. Microstructure characterization reveals the presence of hierarchical macro-, micro- and nano-structures in as-built samples that were very different from SS316L microstructures prepared by other established methods. The formation of a characteristic intragranular cellular segregation network microstructure appears to contribute to the increase of yield strength without losing ductility. Silicon oxide nano-inclusions were formed during the SLM process that generated a micro-hardness fluctuation in the building direction. The combined influence of a cellular microstructure and the nano-inclusions constraints the size of ductile dimples to nano-scale. The crack propagation is hindered by a pinning effect that improves the defect-tolerance of the SLM SS316L. This work proves that it was possible to manufacture SS316L with properties suitable for ITER First Wall panels. Further studies on irradiation properties of SLM SS316L and manufacturing of larger real-size components are needed.