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.
•Preliminary neutronics analysis for alternative fuel cladding materials.•Effectiveness of utilizing different ATF materials on the thermal neutron flux.•Pu-239 inventory for various cladding ...materials during fuel cycle.
This paper presents a preliminary neutronics analysis for Accident Tolerant Fuel (ATF) cladding materials for standard APR-1400 reactor A0 fuel assembly. AMPT, FeCrAl, 304 and 310 stainless steels, and SiC were considered and compared with the original Zircaloy-4 cladding material. A parametric evaluation was done for fuel and cladding materials to confirm the geometry requirements to achieve the end-of-cycle fuel reactivity, and the results were compared with the standard APR-1400 reference fuel-cladding system. Serpent Monte Carlo reactor physics code version 2.31 was utilized to evaluate the associated neutronics penalty when different cladding materials were used such as, fuel reactivity, thermal neutron spectrum, plutonium and isotopic inventory evolution, and fuel assembly linear pin power distribution. In the examined cases, fuel enrichments were fixed, and cladding thickness and pellet diameter were changed for zircaloy, cases 1 – 4. As a result, thermal neutron absorption cross section varies between materials due to higher absorbing cross section leads to hardening of the neutron spectrum in the fuel-cladding system. That leads to a slight increase in the production of actinides in the inventory such as plutonium.
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.
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.
Summary
Climate change is one of the grand global challenges facing the world community. With the global warming threat and the attendant public health risks caused by poor air quality and harmful ...fine particles, the two different energy sources—nuclear and renewables—may have found a common ground and thread to form an alliance to meet these grand global challenges. The latest advent of technologies enables load‐follow flexibility of nuclear power, which has mainly provided baseload power, making nuclear energy an ideal partner for renewable energy, leveling the uncertainty and accommodating the unpredictability associated with renewables. The progress in small modular reactor (SMR) technology, which can be deployed to remote areas, can further facilitate the linking of the two energy resources.
Some investigators have recently pioneered the ideas to inosculate these two energy resources with the aid of energy storage devices. This paper presents a series of case studies on meeting demand forecasts by coupling nuclear and renewable energy resources for various practical scenarios. The paper also proposes a paradigm shift in thinking in order to eliminate (or minimize to a certain extend) the need for energy storage devices in the combined energy production system by replacing the energy storage devices with some industrial facilities to directly utilize any excess power supplied by renewable energy. As an example, a desalination facility appended to the nuclear‐renewable integrated system is shown to absorb surplus power from renewable energy to produce water, thereby satisfying the demand for both power and water in a typical small remote village. Case studies are also performed to extend the concept to include the effect of weather condition and seasonal variation in solar energy conditions. The promising role of disruptive emerging technologies in the nuclear‐renewable combined system is also addressed.
Abstract
Aim
Mental distress, non‐specific symptoms of depression and anxiety, is common in chronic pelvic pain (CPP). It contributes to poor recovery. Women's health nurses operate in ...multidisciplinary teams to facilitate the assessment and treatment of CPP. However, valid cut‐off points for identifying highly distressed patients are lacking, entailing a gap in CPP management.
Design
This instrumental cross‐sectional study identified a statistically derived cut‐off score for the Depression Anxiety Stress Scale‐8 (DASS‐8) among 214 Australian women with CPP (mean age = 33.3, SD = 12.4, range = 13–71 years).
Methods
Receiver operator characteristic curve, decision trees and K‐means clustering techniques were used to examine the predictive capacity of the DASS‐8 for psychiatric comorbidity, pain severity, any medication intake, analgesic intake and sexual abuse. The study is prepared according to the STROBE checklist.
Results
Cut‐off points resulting from the analysis were ordered ascendingly. The median (13.0) was chosen as an optimal cut‐off score for predicting key outcomes. Women with DASS‐8 scores below 15.5 had higher analgesic intake.
Conclusion
CPP women with a DASS‐8 score above 13.0 express greater pain severity, psychiatric comorbidity and polypharmacy. Thus, they may be a specific target for nursing interventions dedicated to alleviating pain through the management of associated co‐morbidities.
Implications for patient care
At a cut‐off point of 13.0, the DASS‐8 may be a practical instrument for recommending a thorough clinician‐based examination for psychiatric comorbidity to facilitate adequate CPP management. It may be useful for evaluating patients' response to nursing pain management efforts. Replications of the study in different populations/countries are warranted.
•New nuclear reactor designs have flexibilities to extend nuclear power applications to new areas.•This paper addresses nuclear power applications in some emerging areas and presents two examples of ...such applications, one on conceptual design of nuclear-propelled vessels to help clean the oceanic environment polluted with massive amounts of plastic wastes, and the other application on complementing renewable energy resources.•The former includes capturing the plastics and recycling them on board the vessel while the latter demonstrates the plausibility of interconnecting the base-load nuclear power and fluctuating renewable power seamlessly.•Both studies rely on SMR technology as the enabler of the applications. Some challenging thermal hydraulic issues associated with these emerging areas are also brought up for future study topics.
The advent of SMR (small modular reactor) technology is enabling a resurgence of nuclear power with its flexibility for versatile applications. This paper addresses emerging areas of nuclear power utilization and presents two examples of potential applications. The study proposes a conceptual design of SMR-propelled vessel to help clean the oceans laden with plastic wastes by capturing and recycling them onboard. Another example of nuclear power application is to complement the limitations inherent in renewable power plants that are being installed at an accelerated pace around the world. Some interesting and challenging thermal hydraulic issues associated with these emerging areas are addressed for future studies.
Traditional neutronics calculations and simulation behavior of plate type research reactors pose a challenge comparing with the conventional pressurized water reactors. This is due to its complex ...geometry, characteristics, heterogeneity, and neutron leakage that lead to modeling difficulties. The Reactor Monte Carlo code (RMC) is employed in stochastic approach for the neutronic analysis in the plate type research reactor. The goal of this report is to examine the capability and validity of the model built using RMC and compare the results with a well-known Monte Carlo code such as MCNP. The results between RMC and MCNP are in a good agreement for effective multiplications factor (keff), radial power peaking factor, total power peaking factor, and integral and differential control rods worth.
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