Advanced Nuclear Energy Systems: Heat Transfer Issues and Trends

Almost 450 nuclear power plants are currently operating throughout the world and supplying about 17% of the world’s electricity. These plants perform safely, reliably, and have no free-release of byproducts to the environment. Given the current rate of growth in electricity demand and the ever growing concerns for the environment, the US consumer will favor energy sources that can satisfy the need for electricity and other energy-intensive products (1) on a sustainable basis with minimal environmental impact, (2) with enhanced reliability and safety and (3) competitive economics. Given that advances are made to fully apply the potential benefits of nuclear energy systems, the next generation of nuclear systems can provide a vital part of a long-term, diversified energy supply. The Department of Energy has begun research on such a new generation of nuclear energy systems that can be made available to the market by 2030 or earlier, and that can offer significant advances toward these challenging goals [1]. These future nuclear power systems will require advances in materials, reactor physics as well as heat transfer to realize their full potential. In this paper, a summary of these advanced nuclear power systems is presented along with a short synopsis of the important heat transfer issues. Given the nature of research and the dynamics of these conceptual designs, key aspects of the physics will be provided, with details left for the presentation

Higher spin fields from a worldline perspective

Higher spin fields in four dimensions, and more generally conformal fields in arbitrary dimensions, can be described by spinning particle models with a gauged SO(N) extended supergravity on the worldline. We consider here the one-loop quantization of these models by studying the corresponding partition function on the one-dimensional torus. After gauge fixing the supergravity multiplet, the partition function reduces to an integral over the corresponding moduli space which is computed using orthogonal polynomial techniques. We obtain a compact formula which gives the number of physical degrees of freedom for all N in all dimensions. As an aside we compute the physical degrees of freedom of the SO(4) = SU(2)xSU(2) model with only a SU(2) factor gauged, which has attracted some interest in the literature.Comment: 21 page

[Experimental studies of fuel-coolant interactions in the Savannah River heavy water reactors]

This report is based on current research being conducted on investigation of the thermal-hydraulic behavior of liquid metal/water interaction and on investigation of the chemical reactivity of gallium and indium in particular

Linear unstable plants with saturating actuators: robust stabilization by a time varying sliding surface

This paper proposes the use of a time-varying sliding surface for the robust stabilization of linear uncertain SISO plants with saturating actuators. A constructive procedure for its design is also proposed, and stability of the closed loop system is proved in the null controllable region. The proposed technique does not require plant stability, and can manage any bounded disturbance term satisfying the matching condition. Theoretical results have been validated by simulation using the missile roll angle control problem

Robust quantized feedback stabilization of linear systems

This paper investigates the feedback stabilization problem for SISO linear uncertain control systems with saturating quantized measurements. In the fixed quantization sensitivity framework, we propose a time varying control law able to effectively account for the presence of saturation, which is often the main source of instability, designed using sliding mode techniques. Such controller is proved able to stabilize the plant both in the presence and in the absence of quantization

Robust control of an underwater ROV in the presence of nonsmooth nonlinearities in the actuators.

In this note a control law dealing with actuator nonlinearities is applied to the position and orientation control of a Remotely Operated Vehicle (ROV) employed by the italian company Snamprogetti. The proposed control law is based on sliding mode control and guarantees robustness with respect to uncertainties present both in the ROV model and in the nonlinearity considered. in order to test the effectiveness of the proposed control law, simulation tests are being performed

Practical stabilization and transient shaping of discrete-time plants with saturating actuators and matched disturbance

This study proposes the use of a time-varying sliding surface for robust transient shaping of linear discrete-time multi-input plants subject to saturating actuators, in the presence of bounded matched uncertainties. A constructive procedure is presented, ultimate boundedness of state trajectories is proved and a result about the choice of tuning parameters for robust transient shaping is given. Simulation results show remarkable improvements in dynamic performances with respect to existing literature