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The accident-tolerant fuel concept involves replacing the conventional cladding system (zirconium) with a new material or coating that has specific thermomechanical properties. The aim of this study is to evaluate the neutronics performance of a chromium coating concept and design solutions. A Zircaloy–uranium fuel system (Zr–U) is currently used as a standard fuel system in pressurized water reactors around the world. This investigation presents the benefits of utilizing an alternative cladding material such as chromium coating and the effects on the thermal neutron parameters of the way in which the chromium coating is introduced in the reactor fuel. Among these significant benefits is an increase in the reactor fuel’s thermal conductivity, which improves reactor safety. Two types of fuel-cladding systems were investigated: Zircaloy–uranium (Zr–U) and Zircaloy–chromium (Zr–Cr–U) coating fuel systems. Neutronics analysis evaluations were performed for the selected fuel assemblies and a two-dimensional full core based on an APR-1400 reactor design. Neutronics analyses were performed for the application of the new fuel-cladding material systems using the reactor-physics Monte Carlo code Serpent 2.31.

The aim of this study is to investigate the potential improvement of accident-tolerant fuels in pressurized water reactors for replacing existing reference zircaloy (Zr) fuel-cladding systems. Three main strategies for improving accident-tolerant fuels are investigated: enhancement of the present state-of-the-art zirconium fuel-cladding system to improve oxidation resistance, replacement of the current referenced fuel-cladding system material with an alternative high-performance oxidation-resistant cladding, and replacement of the current fuel with alternative fuel forms. This study focuses on a preliminary analysis of the neutronic behavior and properties of silicon carbide (SiC)-fuel and FeCrAl cladding systems, which provide a better safety margin as accident-tolerant fuel systems for pressurized water reactors. The typical physical behavior of both cladding systems is investigated to determine their general neutronic performance. The multiplication factor, thermal neutron flux spectrum, 239Pu inventory, pin power distribution, and radial power are analyzed and compared with those of a reference Zr fuel-cladding system. Furthermore, the effects of a burnable poison rod (Gd2O3) in different fuel assemblies are investigated. SiC cladding assemblies present a softer neutron spectrum and a lower linear power distribution compared with the conventional Zr-fuel-cladding system. Additionally, the SiC fuel-cladding system exhibits behaviors that are consistent with the neutronic behavior of conventional Zr fuel-cladding systems, thereby affording greater economic and safety improvements.

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Our aim is to study the neutronic behaviour of potential accident-tolerant fuel (ATF) claddings in a pressurised water reactor under normal operations. This work compares ATF silicon carbide composite (SiC/SiC) cladding to conventional ZIRLOTM cladding in APR-1400. Additionally, a “sandwich” cladding design developed by the CEA is used for SiC/SiC. The design structure includes a liner in between two layers of the composite to ensure leak tightness. The two proposed liners are Niobium (Nb) and Tantalum (Ta). Serpent 2, a Monte Carlo reactor physics lattice code, is employed to model both cladding materials in APR-1400 at three different levels: pin cell, fuel assembly, and core. The criticality, neutron spectrum, actinide inventory, and power distribution as a function of burnup are investigated. The simulations show that SiC/SiC with the Nb liner displays a far superior performance than the Ta liner across all examined characteristics. Ta leads to a harder neutron spectrum and increased Pu-239 content throughout the cycle, while Nb presents negligible effects. In fact, SiC/SiC with the Nb liner performs very similarly to ZIRLOTM at all model levels. The results indicate that, in terms of neutronics, the adoption of the SiC/SiC composite would entail little to no changes to current APR-1400 operations.

Although nuclear energy is a clean and sustainable source, inherent safety concerns have long been recognized and were critically highlighted by the Chernobyl and Fukushima accidents. A significant amount of research is focused on improving accident-tolerant fuel (ATF) technologies to enhance the safety features of reactors. Choosing the right material for the fuel-rod cladding is the most crucial part of the nuclear fuel system and is necessary to develop ATF ideas. Concerning their thermomechanical integrity, high-temperature oxidation resistance, irradiation tolerance, and manufacturability for light-water reactors (LWRs), this review offers a thorough benchmarking of three top ATF cladding candidates - silicon carbide fiber-reinforced silicon carbide composites (SiC f /SiC), iron-chromium-aluminum alloys (FeCrAl), and chromium-coated zirconium alloy (Cr-coated Zr-alloy). Moreover, it addresses the performance metrics gap by elucidating the qualification pathways, including lead test rod campaigns, hermetic joining techniques for SiC f /SiC, weld optimization for FeCrAl, and comprehensive uniformity controls for Cr-coated Zr-alloy. This review further defines an executable R&D plan for the mid-2030s deployment of ATF claddings in current LWR fleets by directly comparing critical criteria and identifying feasible certification and licensing policies.

Background Patients with aggressive lymphomas are at higher risk for venous thromboembolism (VTE). ThroLy is a risk assessment model (RAM) derived to predict the occurrence of VTE in various types of lymphomas. In this study, we assess the clinical application of ThroLy RAM in a unified group of patients with diffuse large B-cell lymphoma (DLBCL). Methods Hospital databases were searched for patients with DLBCL and radiologically-confirmed VTE. Items in the ThroLy RAM, including prior VTE, reduced mobility, obesity, extranodal disease, mediastinal involvement, neutropenia and hemoglobin < 10.0 g/dL, were retrospectively reviewed. Results A total of 524 patients, median age 49 (range: 18-90) years were included. Patients had high disease burden; 57.3% with stage III/IV and 34.0% with bulky disease. All were treated on unified guidelines; 63 (12.0%) had primary refractory disease. Venous thromboembolic events were reported in 71 (13.5%) patients. Among 121 patients with high (> 3) ThroLy score, 22.3% developed VTE compared to 8.4% and 12.4% in those with low and intermediate risk scores, respectively (P = .014). Simplifying the ThroLy model into two risk groups; high-risk (score ≥ 3) and low risk (score < 3) can still segregate patients; VTE developed in 44 (17.2%) high-risk patients (n = 256) compared to 27 (10.1%) in the low-risk group (n = 268), P = .038. Neutropenia, a component of the ThroLy, was encountered in only 14 (2.7%) patients. Conclusions ThroLy RAM can identify patients with DLBCL at high risk for VTE. Model can be modified by dividing patients into two, rather than three risk groups, and further simplified by omitting neutropenia.

The United Arab Emirates (UAE) launched its nuclear energy program in 2008, achieving notable outcomes with the 'UAE Policy on the Peaceful Use of Nuclear Energy' program. This initiative is dedicated to ensuring the operational safety, reliability, and efficient operation of its advanced nuclear reactor (APR-1400) power plants. In the aftermath of the Fukushima incident, the global nuclear fuel research and development community shifted toward developing accident-tolerant fuels (ATFs). ATFs are purposefully engineered and manufactured to withstand delayed periods of core cooling system disruption, thereby significantly enhancing safety compared to conventional fuel systems while maintaining or improving normal operational performance. This research investigates the feasibility of implementing ATFs as the primary nuclear fuel source within APR-1400 nuclear reactor and evaluates their potential effect on the operational parameters and safety. In order to accomplish this objective, comprehensive review and assessments of the potential ATFs, including neutronics, thermal-hydraulic, thermomechanical/chemical, and fuel performance evaluations, were conducted, encompassing multiple candidate ATF concepts. This research aims to overview ongoing research efforts and prospective ATF concepts for near-future implementation within APR-1400 nuclear power plants.

In 2010, the Department of Nuclear Engineering at Khalifa University of Science and Technology (NUCE) established the MSc degree in Nuclear Engineering. This program was established to support the United Arab Emirates (UAE) emerging civil nuclear energy program and produce graduate engineers capable of supporting the safe construction, operation, maintenance and eventual decommissioning of the UAE nuclear reactors. In order to enhance and consolidate classroom teaching, an overseas “Field Trip” module was integrated into the MSc curriculum in order to provide practical exercises, demonstrations and site visits. With respect to the consolidation of reactor physics teaching in particular, the field trips over the past 9 years have utilized mainly the AGN Zero Power reactor at Kyung Hee University (2012-2015) and the Breazeale TRIGA reactor at Penn State University (2017-2018). In both cases students gained “hands-on” supervised experience in classical reactor experiments, shielding measurements, health physics and radiological protection control, and radioanalytical measurement methods, such as neutron activation analysis. At Penn State University, the experiments were extended to surveillance measurements, taking advantage of the facilities specialized modules in nuclear security. This paper provides details of the arrangements made for the field trips and the learning outcomes these practical arrangements helped to satisfy meeting the overall degree outcomes. The case study will also illustrate where a nuclear energy newcomer State can take advantage of international collaborations without the need to invest in a national research reactor.