Canadian Nuclear Laboratories

Legacy landfill sites often contain buried trenches that are not well delineated, not documented to modern standards, with subsurface voids that can act as preferential pathways for water, sediment and contaminants. To evaluate whether geophysical methods can help identify these features in a landfill, we conducted integrated electrical resistivity tomography (ERT) and ground-penetrating radar (GPR) survey along three collocated transects; at a closed 1950’s landfill site in Ontario, Canada. The survey used a multi-electrode ERT array and a 250 MHz GPR to image shallow structures associated with historical waste trenches and potential soil-pipe development.The survey results reveal a consistent pattern: high-resistivity anomalies in ERT between 1-2 m depth align with wide, crossing hyperbolas in the respective GPR profiles. The high-resistivity anomalies are interpreted as waste trenches. Located between the identified trenches, elongated resistive zones corresponding to GPR troughs and dipping reflectors, are tentatively interpreted as sedimentary layers with possible soil-pipe-like connections. These results, overlaid with site monitoring data, will improve the overall clarity and allow a better understanding of these subsurface structures. Three trench-like structures with two connecting anomalies are imaged along each transect, demonstrating a repeating subsurface pattern. Deeper ERT anomalies (4-9 m) lack GPR counterparts due to the limited penetration of the 250 MHz antenna Further surveys will use different antenna types to achieve deeper resolutions.The study results show that combining ERT resistivity contrasts with GPR hyperbola geometry, provides a reliable means of mapping buried trenches and potential erosion pathways at legacy landfill sites. Next steps include expanding the survey grid, forward modeling, integrating other geophysical methods that complements ERT and GPR, and developing 3D interpretations to support long-term environmental monitoring and risk assessment.

This short communication describes a spontaneous hemangiosarcoma within the abdomen, which appeared to have originated from the prostate gland area with infiltration, and that metastasized to the lungs in a 46-week-old male Sprague-Dawley rat. At necropsy, a 90 mm × 60 mm × 50 mm dark cystic neoplastic mass was present in the abdomen and the lung lobes had multiple dark cystic neoplastic structures. The abdominal mass was necrotic with a few peripheral areas of plump oval cells and frond-like structures lined by spindle-shaped cells. The lung neoplastic cysts were filled with blood and there were foci of plump oval cells within and peripheral to the cysts, as well as multiple small clusters throughout the lung parenchyma. Neoplastic cells of the abdominal mass and lung cysts stained positively for von Willebrand Factor by immunohistochemistry, indicating a vascular endothelial cell origin and consistent with a diagnosis of hemangiosarcoma. The lung hemangiosarcomas were considered metastases from the abdominal hemangiosarcoma based on their similar cellular morphology and multiple foci throughout the lung lobes.

Established in 2008 as a joint research project, the Enhanced Sealing Project (ESP) investigated the performance and Thermal-Hydraulic-Mechanical (THM) evolution of a full-scale composite seal at Canada's Underground Research Laboratory (URL). The seal was highly instrumented and comprised of a ∼6-m-thick bentonite clay component sandwiched between ∼3-m-thick concrete components, installed in a ∼5-m-diameter vertical circular shaft at the depth of ∼270 meters below the ground surface. This study utilized the ESP results up to 2024 and URL's historical data from the 1980s, to assess the performance and behaviour of the composite seal at the URL and the maturity of sealing technology for a Deep Geological Repository (DGR). The findings suggest that: (a) groundwater level perturbation can be minimized after the URL closure, (b) the preliminary swelling pressure of the composite seal can meet the required design specifications, and (c) full-scale composite seals can be constructed using existing techniques - demonstrating maturity of DGR sealing technologies. Finally, the ESP and URL have created a comprehensive dataset spanning over 46 years, covering the entire lifecycle of an underground facility – from siting, construction, operation, closure, and post-closure stages, which supports the development of a DGR's design and safety case.

The oxytocin/oxytocin receptor (OT/OTR) signalling system is involved in socioemotional behaviours, garnering interest as a therapeutic target across multiple clinical conditions. Despite its potential, our limited understanding of how to optimally target it and the scarcity of molecular tools for in vivo studies hinder therapeutic development. Molecular imaging techniques, such as Positron Emission Tomography (PET), can bridge this gap by furnishing direct insights into ligand biodistribution, receptor visualisation and ligand-receptor engagement. Here, we report the design, synthesis and biochemical and pharmacological characterisation of five OT-like peptides as novel PET tracers for investigating the OT/OTR signalling system. dOTK8[SFB] emerged as the most promising OT-like lead. The radioactive version [18F]dOTK8[SFB] was produced using a microfluidic reaction approach and validated by preclinical PET imaging of healthy rats after intravenous ligand administration. [18F]dOTK8[SFB] exhibited specific accumulation in OTR-rich tissues, affirming OTR-specificity and suitability as a new OT-like PET radiotracer for investigating OT/OTR biodistribution in humans.

This review comprehensively explores low-carbon construction materials for pavements, emphasizing their role in advancing sustainable infrastructure. It examines various material types—including recycled, industrial by-products, and bio-based alternatives—highlighting their properties, availability, and suitability for pavement applications. Performance metrics such as mechanical strength, durability, environmental impact, and life cycle assessments are discussed in detail. Real-world case studies demonstrate successful implementations, underscoring practical benefits. The review also identifies key challenges—including technological, economic, and regulatory barriers—and proposes directions for future research. Overall, the findings affirm that integrating low-carbon materials in pavement construction offers significant potential for reducing carbon emissions and promoting sustainable development.