•A conceptual design of a 3 MWth heat pipe cooled micro reactor was proposed.•Steady-state neutronics and thermal-hydraulics analyses were performed.•Key neutronics and thermal hydraulics safety ...parameters were evaluated.•Burnup calculations were performed using both MCNP and SERPENT Monte Carlo codes.•Preliminary thermal hydraulic analysis was performed using STAR CCM+ CFD software.
Micro reactors are gaining substantial interest worldwide due to their capabilities to deliver power to remote and decentralized areas and their long fuel cycles, making them more attractive than other energy sources. This paper presents a conceptual design and steady-state neutronics and thermal-hydraulics analyses results for a heat pipe cooled yttrium hydride moderated micro reactor. The reactor was designed for both terrestrial and space application purposes; hence, size and weight were important. The neutronics analysis calculations were performed to evaluate key safety parameters such as control devices reactivity worth, temperature reactivity coefficients, and power distribution of the reactor core. Burnup calculations were performed using Monte Carlo code MCNP6.2 and verified against Serpent code results. The thermal-hydraulics analyses calculations were performed to evaluate the temperature distribution in a representative unit cell in the reactor core using the STAR CCM+ multi-physics computational fluid dynamics (CFD) software by utilizing the power distribution obtained from neutronics calculations. It was demonstrated that this reactor could be operated safely for more than 11 years, generating 3 MW of thermal power.
A cloud computing model gives cloud service providers the ability to retain multiple workloads on a single physical system. However, efficient resource provisioning and possible system fault ...management in the cloud can be a challenge. Early fault detection can provide room to recover from potential faults before impacting QoS. Current static techniques of fault management in computing systems are not satisfactory enough to safeguard the QoS requested by cloud users. Thus, new smart techniques are needed. This paper presents the ACCRS framework for cloud computing infrastructures to advance system’s utilization level, reduce cost and power consumption and fulfil SLAs. The ACCRS framework employs Autonomic Computing basic components which includes state monitoring, planning, decision making, fault predication, detection, and root cause analysis for recovery actions to improve system’s reliability, availability, and utilization level by scaling resources in response to changes in the cloud system state.
Increasingly, Cyber–physical Systems are expected to operate in different environments and interconnect with a diverse set of systems, equipment, and networks. This openness to heterogeneity, ...diversity, and complexity introduces a new level of vulnerabilities, which adds to the consistent need for security including the digital forensics capabilities. Digital investigators utilize the information on the attacker’s computer to find clues that may help in proving a case. One aspect is the digital evidence that can be extracted from the main memory (RAM), which includes live information about running programs. A program’s states, represented by variables’ values, vary in their scope and duration. This paper explores RAM artifacts of Java programs. Because JVMs can run on various platforms, we compare the same program on three different implementations of JVM from forensic perspectives. Our investigation model assumes no information is provided by the underlying OS or JVM. Our results show that a program’s states can still be extracted even after the garbage collector is explicitly invoked, the software is stopped, or the JVM is terminated. This research helps investigators identify the software used to launch the attack and understand its internal flows. Investigators can utilize this information to accuse the perpetrators and recover from attacks.
•A least square fitting approach is proposed to estimate the fuel burnup for the plate type fuel assembly of research reactors.•Linear and nonlinear fitting methods are derived by using parameters ...such as power density, enrichment and fuel density.•Three different cores with U3Si2 and UMo fuels are taken into consideration for application of the proposed method.
This work is focused on estimation of burnup for a plate type fuel assembly of research reactors with the SCALE6 code sequences such as TRITON/NEWT and ORIGEN-ARP. And a simple and accurate model is proposed to calculate burnup based on the least square fitting method without additional depletion analyses. One fuel assembly is modeled and its burnup is obtained for different power densities, enrichments, and fuel densities. Linear and non-linear polynomial fitting methods are used to provide a suitable formula for the burnup of the plate type fuel assembly with a function of different parameters. And the proposed approach is applied to three configurations of research reactors, such as a 5MW core of U3Si2 fuel, 3MW cores with U3Si2 and UMo fuels. The results are also validated by comparing those of Monte Carlo codes.
•We applied nonlinear unified nodal method for 10MW IAEA MTR benchmark problem.•TRITION–NEWT system was used to obtain two-group burnup dependent cross sections.•The criticality and power ...distribution compared with reference (IAEA-TECDOC-233).•Comparison between different fuel materials was conducted.•Satisfactory results were provided using UNM for MTR core calculations.
Nodal diffusion methods are usually used for LWR calculations and rarely used for research reactor calculations. A unified nodal method with an implementation of the coarse mesh finite difference acceleration was developed for use in plate type research reactor calculations. It was validated for two PWR benchmark problems and then applied for IAEA MTR benchmark problem for static calculations to check the validity and accuracy of the method. This work was conducted to investigate the unified nodal method capability to treat material testing reactor cores. A 10MW research reactor core is considered with three calculation cases for low enriched uranium fuel depending on the core burnup status of fresh, beginning-of-life, and end-of-life cores. The validation work included criticality calculations, flux distribution, and power distribution; in addition, a comparison between different fuel materials with the same uranium content was conducted. The homogenized two-group cross sections were generated using the TRITON–NEWT system. The results were compared with a reference, which was taken from IAEA-TECDOC-233. The unified nodal method provides satisfactory results for an all-rod out case, and the three-dimensional, two-group diffusion model can be considered accurate enough for MTR core calculations.
We present in this paper a unified paradigm for the verification and validation of software and systems engineering design models expressed in UML 2.0 or SysML. This paradigm relies on an established ...synergy between three salient approaches, which are model-checking, program analysis, and software engineering techniques. To illustrate the accomplishment of our results, we have designed and implemented an integrated and automated computer-aided assessment tool. We provide three case studies for sequence, state machine, and class and package diagrams to demonstrate the benefits of our methodology
