INSTRUMENTATION AND CONTROL STRATEGIES FOR AN INTEGRAL PRESSURIZED WATER REACTOR

BELLE R. UPADHYAYA,MATTHEW R. LISH,J. WESLEY HINES,RYAN A. TARVER 한국원자력학회 2015 Nuclear Engineering and Technology Vol.47 No.2

Several vendors have recently been actively pursuing the development of integral pressurizedwater reactors (iPWRs) that range in power levels from small to large reactors. Integral reactors have the features of minimum vessel penetrations, passive heat removalafter reactor shutdown, and modular construction that allow fast plant integration and asecure fuel cycle. The features of an integral reactor limit the options for placing controland safety system instruments. The development of instrumentation and control (I&C)strategies for a large 1,000 MWe iPWR is described. Reactor system modelingdwhich includesreactor core dynamics, primary heat exchanger, and the steam flashing drumdis animportant part of I&C development and validation, and thereby consolidates the overallimplementation for a large iPWR. The results of simulation models, control development,and instrumentation features illustrate the systematic approach that is applicable to integrallight water reactors

DEVELOPMENT OF A RECONFIGURABLE CONTROL FOR AN SP-100 SPACE REACTOR

나만균,BELLE R. UPADHYAYA 한국원자력학회 2007 Nuclear Engineering and Technology Vol.39 No.1

In this paper, a reconfigurable controller consisting of a normal controller and a standby controller is designed to control the thermoelectric (TE) power in the SP-100 space reactor. The normal controller uses a model predictive control (MPC) method where the future TE power is predicted by using support vector regression. A genetic algorithm that can effectively accomplish multiple objectives is used to optimize the normal controller. The performance of the normal controller depends on the capability of predicting the future TE power. Therefore, if the prediction performance is degraded, the proportional-integral (PI) controller of the standby controller begins to work instead of the normal controller. Performance deterioration is detected by a sequential probability ratio test (SPRT). A lumped parameter simulation model of the SP-100 nuclear space reactor is used to verify the proposed reconfigurable controller. The results of numerical simulations to assess the performance of the proposed controller show that the TE generator power level controlled by the proposed reconfigurable controller could track the target power level effectively, satisfying all control constraints. Furthermore, the normal controller is automatically switched to the standby controller when the performance of the normal controller degrades.

DEVELOPMENT OF A RECONFIGURABLE CONTROL FOR AN SP-100 SPACE REACTOR

Na Man-Gyun,Upadhyaya Belle R. Korean Nuclear Society 2007 Nuclear Engineering and Technology Vol.39 No.1

In this paper, a reconfigurable controller consisting of a normal controller and a standby controller is designed to control the thermoelectric (TE) power in the SP-100 space reactor. The normal controller uses a model predictive control (MPC) method where the future TE power is predicted by using support vector regression. A genetic algorithm that can effectively accomplish multiple objectives is used to optimize the normal controller. The performance of the normal controller depends on the capability of predicting the future TE power. Therefore, if the prediction performance is degraded, the proportional-integral (PI) controller of the standby controller begins to work instead of the normal controller. Performance deterioration is detected by a sequential probability ratio test (SPRT). A lumped parameter simulation model of the SP-100 nuclear space reactor is used to verify the proposed reconfigurable controller. The results of numerical simulations to assess the performance of the proposed controller show that the TE generator power level controlled by the proposed reconfigurable controller could track the target power level effectively, satisfying all control constraints. Furthermore, the normal controller is automatically switched to the standby controller when the performance of the normal controller degrades.

An autonomous control framework for advanced reactors

Richard T. Wood,Belle R. Upadhyaya,Dan C. Floyd 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.5

Several Generation IV nuclear reactor concepts have goals for optimizing investment recovery throughphased introduction of multiple units on a common site with shared facilities and/or reconfigurableenergy conversion systems. Additionally, small modular reactors are suitable for remote deployment tosupport highly localized microgrids in isolated, underdeveloped regions. The long-term economicviability of these advanced reactor plants depends on significant reductions in plant operations andmaintenance costs. To accomplish these goals, intelligent control and diagnostic capabilities are neededto provide nearly autonomous operations with anticipatory maintenance. A nearly autonomous controlsystem should enable automatic operation of a nuclear power plant while adapting to equipment faultsand other upsets. It needs to have many intelligent capabilities, such as diagnosis, simulation, analysis,planning, reconfigurability, self-validation, and decision. These capabilities have been the subject ofresearch for many years, but an autonomous control system for nuclear power generation remains as-yetan unrealized goal. This article describes a functional framework for intelligent, autonomous control thatcan facilitate the integration of control, diagnostic, and decision-making capabilities to satisfy theoperational and performance goals of power plants based on multimodular advanced reactors.

Maintenance-based prognostics of nuclear plant equipment for long-term operation

Zachary Welz,Jamie Coble,Belle Upadhyaya,Wes Hines 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.5

While industry understands the importance of keeping equipment operational and well maintained, theimportance of tracking maintenance information in reliability models is often overlooked. Prognosticmodels can be used to predict the failure times of critical equipment, but more often than not, thesemodels assume that all maintenance actions are the same or do not consider maintenance at all. Thisstudy investigates the influence of integrating maintenance information on prognostic model predictionaccuracy. By incorporating maintenance information to develop maintenance-dependent prognosticmodels, prediction accuracy was improved by more than 40% compared with traditional maintenanceindependent models. This study acts as a proof of concept, showing the importance of utilizing maintenance information in modern prognostics for industrial equipment.

Dynamics and control of molten-salt breeder reactor

Vikram Singh,Matthew R. Lish,Ond rej Chv ala,Belle R. Upadhyaya 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.5

Preliminary results of the dynamic analysis of a two-fluid molten-salt breeder reactor (MSBR) system arepresented. Based on an earlier work on the preliminary dynamic model of the concept, the modelpresented here is nonlinear and has been revised to accurately reflect the design exemplified in ORNL-4528. A brief overview of the model followed by results from simulations performed to validate themodel is presented. Simulations illustrate stable behavior of the reactor dynamics and temperaturefeedback effects to reactivity excursions. Stable and smooth changes at various nodal temperatures arealso observed. Control strategies for molten-salt reactor operation are discussed, followed by an illustration of the open-loop load-following capability of the molten-salt breeder reactor system. It isobserved that the molten-salt breeder reactor system exhibits “self-regulating” behavior, minimizing theneed for external controller action for load-following maneuvers.