Neutron beams provide an ideal tool for studying the structural and magnetic properties of novel materials.  In particular, neutron diffraction (or elastic neutron scattering) can be used to reveal detailed information about atomic and crystalline structure.  This is essential for understanding the relationship between the structure and function of advanced materials, or in the case of many nuclear applications, investigating how these relationships change under extreme conditions of temperature, pressure, and irradiation.

The McMaster Nuclear Reactor (MNR) is the only facility in Canada which provides access to neutron beams for materials research.  The MNR is currently home to two instruments for neutron diffraction: the McMaster Alignment Diffractometer (MAD) and the McMaster Small Angle Neutron Scattering facility (MacSANS).  These two instruments are highly complementary, with MAD intended for the study of simple atomic structures and crystalline solids, and MacSANS optimized for more complex structures and nanoscale materials.  The goal of this project is to test and develop new experimental capabilities for neutron diffraction at high temperatures and/or high pressures at the McMaster Nuclear Reactor, and for characterizing the properties of irradiated (and potentially radioactive) materials using neutron beams.  This project is well-aligned with CNL’s research interests in studying the effects of extreme conditions on in-reactor materials and components for CANDU and other advanced reactors.

Quantum materials are a family of compounds which display unique or unusual physical properties due to the effects of quantum mechanics.  This includes materials such as high temperature superconductors (which display perfect diamagnetism and no electrical resistance) and quantum spin liquids (which display exotic quantum statistics and remain magnetically disordered down to the lowest measurable temperatures).

Neutron beams are an essential tool for investigating the properties of novel quantum materials, and for identifying the presence (or absence) of exotic quantum states.  In particular, neutrons offer unparalleled sensitivity to magnetism, which can be used to reveal the characteristic signatures of magnetic order and magnetic phase transitions.  The McMaster Nuclear Reactor (MNR) is currently the only facility in Canada which provides access to neutron beams for materials research.  The MNR is home to two instruments for neutron diffraction: the McMaster Alignment Diffractometer (MAD) and the McMaster Small Angle Neutron Scattering facility (MacSANS).  The MAD instrument is particularly well-suited to the study of quantum materials, with capabilities for carrying out neutron diffraction measurements as a function of temperature (from T = 6 K up to T = 800 K), pressure (up to P = 2 GPa), doping, and irradiation.  The goal of this project will be to explore the structural and magnetic phase diagrams of new superconductors and quantum spin liquid candidates, and to investigate how the quantum states in these materials can be tuned under a broad range of sample conditions.

This project is well-aligned with CNL’s research interests in emerging quantum technologies and novel materials.  In particular, the study of quantum materials is essential for developing new technologies that can address the nation’s quantum needs (in nuclear, defence, and space industries). This includes applications such as quantum sensors, quantum communications, and quantum computing.

The goal of this CNL summer research program research assignment is to synthesize and assay a derivative of 18F-labelled PET (positron emission tomography) radiopharmaceutical [18F]FRho6G-DEG. Rhodamines are a class of positively-charged fluorescent dyes which exhibit affinity for mitochondria-rich cardiomyocytes, and as such [18F]FRho6G-DEG is being investigated as a potential myocardial perfusion imaging agent. The successful student collaborator will be expected to synthesize an analogue of [18F]FRho6G-DEG that can be labelled via nucleophilic aromatic 18F-fluorination (vs nucleophilic aliphatic substitution), along with its 19F standard. They will then optimize the radiosynthesis this novel cardiac imaging agent and asses it for various radiochemical parameters important to PET imaging (e.g. lipophilicity, molar activity).

The final phases of this project will involve assessment of a) uptake of the radiotracer into heart cells in vitro; b) ex vivo biodistribution in healthy rats and c) small animal PET imaging in healthy rats.

To contribute to Canada’s efforts to deal with the climate emergency and ensure energy security, expansion of small nuclear power plants is being considered. The siting of small modular reactors (SMR) where they are needed in remote communities is very attractive as we all want reliable electricity. While there are obvious benefits, there may be major impacts in pristine environments due to infrastructure associated with mining, milling, enrichment, transport and eventual disposal of uranium used for fuel. Our proposal seeks to quantify the environmental impacts in 3 ways. 1. Using the Chalk River site where an SMR is planned, our student will determine baseline biodiversity indices and establish baseline biomarker status for bio-indicators of ecosystem health so that future monitoring can track any adverse impacts of SMRs, i.e. we will determine the current ecosystem health status so changes can be detected.

Recent studies shown that Alpha-fetoprotein receptor is expressed on most cancers and myeloid derived suppressor cells (MDSCs) but generally absent on normal tissues. Non-glycosylated recombinant form of human alpha fetoprotein (AFP), the natural ligand for the AFP receptor, has been successfully conjugated with p-isothiocyanatobenzyldesferrioxamine (SCN-DFO). [¹²⁵I]-AFP was previously prepared by direct radioiodination of AFP and used for biodistribution studies in healthy and COLO-205 tumor bearing mice. [¹²⁵I]-AFP biodistribution studies after thyroid blocking with 1%KI demonstrated the highest tumour to blood ratio of 2.75 at 168 h post injection (p.i.) and cleared from most organs including liver and kidney by 48 h p.i. Further studies are required to use [¹²⁵I]-AFP for in vitro competitive binding studies to determine binding affinity of DFO-AFP to AFP receptors. Further studies are required for DFO conjugation of AFP and its characterization by ESI-MS and MALDI-MS to avoid a decrease of AFP affinity to its receptor. AFP conjugate having well characterized DFO/molecule will be radiolabeled with zirconium-89 (Zr-89) for in vitro and in vivo studies. Preliminary studies with [⁸⁹Zr]-DFO-AFP in non-tumor bearing mice have shown that at 96 hours p.i., [⁸⁹Zr]-DFO-AFP cleared most tissues with the highest uptake (5-11 %ID/g) in liver, gallbladder and spleen. Tumor uptake and in vivo specificity of the trace are required to study biodistribution, specific binding as well as to perform imaging studies in AFP receptors expressing COLO-205 tumor xenograft.

TRISO particles are small (1 mm diameter) spheres that contain the uranium and are randomly packed to form a fuel pin.  You know from your courses how to calculate heat flow in spherical geometries with fixed boundary conditions.  (If you don’t, that’s ok, too) Here we have a collection of spheres, and the boundary conditions are not really fixed.  You will be given a code (either written in C or a commercial code) that performs a very approximate calculation of the problem with brute force.  You may be doing coding to make this program work, and then running several cases.  Alternatively, you may use a commercial or open-source code such as OpenFOAM to solve this problem.  You will learn about heat flow (and its effect on nuclear reactors).  You will be working with a graduate student who has experience in this field and who is responsible for the neutronic side of the calculation.  This work is also done in collaboration with Canadian Nuclear Laboratories.

Early successful nuclear fusion reactor designs will likely be based on D-T (deuterium-tritium) fusion, because the plasma temperatures for this reaction are lower than for other reactions. While deuterium is an abundant isotope, tritium does not occur naturally and has a half-life of about 12 years. The current plan is that the fusion reactor itself will breed the tritium in a lithium blanket surrounding the fusion plasma, using the neutrons created in the fusion process. The summer research proposed here is to perform initial simulations of this process in the environment of a Stellarator, which is one of the promising designs for fusion reactors. This would involve creating a model of a Stellarator design, e.g. the Wendelstein 7-X in a state-of-the-art simulation code such as GEANT4 and/or OpenMC.   The OpenMC code is widely used in nuclear fission research, while GEANT4 originated from particle physics, but has wide applications in other areas, e.g. medical imaging, as well.

The objective is to develop a bench-top low temperature molten salt exposure methodology to study dealloying corrosion susceptibility of structural Cr-containing alloys as it pertains to molten salt reactors. The idea is to assembly a bench top molten salt pot consisting of a small volume ceramic-lined alloy autoclave (Parker Autoclave Engineers) and suitable crucible furnace capable of heating and containing a low temperature. molten chloroaluminate electrolyte (NaCl–KCl–AlCl3); composition of 26:13:61, mol/mol, with KCl specifically added to reduce the vapour pressure. This mixture has the advantage, due to polymerization of chloroaluminates, to force the melting point of the mixture to drop below the boiling point of water, and thus improve the capability of making low temperature electrochemical measurements. As Al metal is thermodynamically stable in the alkali-chloroaluminate melt, it will be used as a pseudo reference electrode and the counter electrode to permit electrochemical potentiodynamic polarization measurements to be made on metal wires of the major alloying elements of the candidate structural alloys namely Fe, Cr and Ni. Development of such a capability is requisite in proving a physical description of dealloying corrosion as it occurs in molten salt electrolytes. The CNL intern will be mentored by Zayaan Kahn (MASc student) and Dr. Jiji Joseph (Research Associate), in addition to myself, in developing and applying the proposed methodology. will be mentored. The student can then work with CNL staff during the internship on-site to perform molten salt exposure of candidate alloys in the molten chloroaluminate electrolyte using research instruments and tools available.

Students will investigate a variety of nuclear materials, in both the as-synthesized and radiation-damaged state. Irradiations will be performed using the McMaster Nuclear Reactor and the McMaster accelerator laboratory. Samples will be characterized primarily via Doppler-broadened Positron Annihilation Spectroscopy to measure the formation and clustering of atomic scale vacancies and vacancy clusters within the first micron of the material surface, and Positron Annihilation Lifetime Spectroscopy to measure the formation of larger scale void spaces and blistering in the bulk of the material. Additional characterization could include electron microscopy and/or x-ray diffraction. 

This work will occur on McMaster campus in the Tandem Accelerator Building, the Nuclear Research Building and the McMaster Nuclear Reactor. Specific tasks could include: sample handling and preparation, operating laboratory apparatus, computational data analysis, writing laboratory control software, literature review, correspondence and collaboration with other research groups, installing high-vacuum components, electronic assembly, heavy manual labour, work with power tools, close and/or delicate work. 

TRistructural-ISOtropic (TRISO) fuel is the key advancing technology for advanced Small Modular Reactors and the Generation-IV Very High Temperature Reactors. A typical TRISO particle comprises four concentric spherical layers encasing a fuel kernel (UO2 or UCO), which includes the buffer (porous carbon), Inner Pyrolytic Carbon (IPyC), Silicon Carbide (SiC) and Outer Pyrolytic Carbon (OPyC), all of which contribute to TRISO’s physical integrity and resistance to high temperatures. The SiC layer plays the role of a pressure boundary that can withstand the build-up of internal pressure during the fission reaction and as a barrier for diffusion of gaseous and metallic fission products. Performing mechanical strength studies of the SiC layer at elevated temperatures (~1000°C) would further the understanding of the fracture properties of SiC.

X-ray computed tomography (XCT) is an emerging non-destructive characterization technique that can be used to examine the 3D microstructure of materials. By using XCT, laborious, invasive, and challenging sample preparation steps are bypassed and instead a 3D image of the internal structure of a sample is obtained. With respect to TRISO fuel and nuclear materials in general, pairing XCT with in-situ elevated temperature and mechanical testing capabilities can reveal a deeper mechanistic understanding of the degradation and failure than what is currently available.

The proposed summer student project between McMaster University, Canadian Centre for Electron Microscopy (CCEM) and Canadian Nuclear Laboratories (CNL) aims to have the student complete the following tasks:

• perform a literature review on the application of XCT for the examination of TRISO fuel,
• optimize image acquisition and scanning parameters on CNL-supplied surrogate TRISO particles in as-fabricated state,
• learn post-processing techniques and methodologies for XCT data,
• assist in the design, development, validation and testing of elevated temperature testing stage for high-temperature mechanical testing using CCEM XCT,
• develop a test plan for high-temperature mechanical testing of surrogate TRISO particles at CCEM, and
• observe room temperature mechanical XCT testing of surrogate TRISO particles at CNL.

TRistructural-ISOtropic (TRISO) fuel is the key advancing technology for advanced Small Modular Reactors and the Generation-IV Very High Temperature Reactor variant. A typical TRISO particle comprises four concentric spherical layers encasing a fuel kernel (UO2 or UCO), which includes the buffer (porous carbon), Inner Pyrolytic Carbon (IPyC), Silicon Carbide (SiC) and Outer Pyrolytic Carbon (OPyC), all of which contribute to TRISO’s physical integrity and resistance to high temperatures. The SiC layer plays the role of a pressure vessel that can withstand the build-up of internal pressure during the fission reaction and as a barrier for diffusion of gaseous and metallic fission products (FP).

Importantly, an understanding of the thermal-mechanical performance of the SiC layer in TRISO fuel in neutron irradiated states at high operating temperatures requires a further understanding of radiation induced microstructural changes and on the FP transport mechanisms. Nano-scale characterisation techniques, such as Atom Probe Tomography (APT) and High Resolution Transmission Electron Microscopy (HR-TEM), would improve the understanding of the transport mechanisms of FPs in neutron irradiated TRISO particles. In preparation of receiving neutron irradiated fueled TRISO particles at CNL, sample preparation and experimental methodology development is required for APT examination. It is therefore proposed to use surrogate as-fabricated and proton irradiated TRISO particles to establish this analytical capability during a McMaster/CNL summer student project.

The goals of this effort includes:

• performing a literature review on microstructure evolution of TRISO particle layers due to irradiation damage and relevant microscopy techniques (FIB/APT/TEM),
• developing a sample preparation procedure and fabricating the APT specimens from SiC layer and interfaces by using FIB technique (CCEM),
• performing APT characterisation on CNL supplied surrogate TRISO particles (as-fabricated and proton irradiated),
• investigating using TEM with STEM/EDS techniques to ensure the prepared LEAP tips contain features of interest (to be performed at McMaster or CNL),
• obtaining accurate 3D compositional information from the grain boundaries or/and grain interiors,
• gaining insights into 3D spatial distribution of any irradiation induced products in the SiC layer of proton irradiated surrogate TRISO particles by using APT at McMaster University, and
• observing the microscopy investigation sessions of samples at CNL.

The challenging conditions prevalent in reactor environments, characterized by factors such as neutron irradiation and elevated temperatures, instigate noteworthy modifications in material properties. These alterations impose limitations on the operational efficiency and safety thresholds of diverse reactor types. Furthermore, there exists a significant dearth of data concerning the performance of various nuclear materials in these extreme environments. This scarcity of information is crucial for the scientific community, especially in the design and development of small modular reactors and other advanced reactor types. This project aims to conduct a materials assessment of SiC at moderately elevated temperatures. The primary focus will be on developing testing techniques for elevated temperatures and determining the elastic-plastic properties (hardness, elastic modulus) of the selected material.