http://localhost:8080/xmlui/handle/123456789/2369 2026-06-23T06:33:51Z 2026-06-23T06:33:51Z Munje, R. K. Parkhe, J. G. Patre, B.M. http://localhost:8080/xmlui/handle/123456789/2869 2020-12-11T10:43:30Z 2014-11-21T00:00:00Z

Title: Control of xenon oscillations in Advanced Heavy Water Reactor via two-stage decomposition Authors: Munje, R. K.; Parkhe, J. G.; Patre, B.M. Abstract: Xenon induced spatial oscillations developed in large nuclear reactors, like Advanced Heavy Water Reactor (AHWR) need to be controlled for safe operation. Otherwise, a serious situation may arise in which different regions of the core may undergo variations in neutron flux in opposite phase. If these oscillations are left uncontrolled, the power density and rate of change of power at some locations in the reactor core may exceed their respective thermal limits, resulting in fuel failure. In this paper, a state feedback based control strategy is investigated for spatial control of AHWR. The nonlinear model of AHWR including xenon and iodine dynamics is characterized by 90 states, 5 inputs and 18 outputs. The linear model of AHWR, obtained by linearizing the nonlinear equations is found to be highly ill-conditioned. This higher order model of AHWR is first decomposed into two comparatively lower order subsystems, namely, 73rd order ‘slow’ subsystem and 17th order ‘fast’ subsystem using two-stage decomposition. Composite control law is then derived from individual subsystem feedback controls and applied to the vectorized nonlinear model of AHWR. Through the dynamic simulations it is observed that the controller is able to suppress xenon induced spatial oscillations developed in AHWR and the overall performance is found to be satisfactory

2014-11-21T00:00:00Z Munje, R. K. Patre, B. M. Shimjith, S. R. Tiwari, A. P. http://localhost:8080/xmlui/handle/123456789/2814 2020-12-02T09:50:52Z 2013-08-01T00:00:00Z

Title: Sliding Mode Control for Spatial Stabilization of Advanced Heavy Water Reactor Authors: Munje, R. K.; Patre, B. M.; Shimjith, S. R.; Tiwari, A. P. Abstract: Spatial oscillations in neutron flux distribution resulting from xenon reactivity feedback are a matter of concern in large nuclear reactors. If the spatial oscillations in power distribution are not controlled, power density and rate of change of power at some locations in the reactor core may exceed their respective limits causing increase in chances of fuel failure. Hence, during the design stages of any large nuclear reactor, it is essential to identify the existence of spatial instabilities and to design suitable control strategy for regulating the spatial power distribution. This paper presents a method to design and analyze the effect of sliding mode control (SMC) for spatial control of Advanced Heavy Water Reactor (AHWR). The AHWR model considered here is of 90th order with 5 inputs and 18 outputs. In this paper, numerically ill-conditioned system of AHWR is separated into 73rd order ‘slow’ subsystem and 17th order ‘fast’ subsystem and SMC is designed from slow subsystem. Further, using simple linear transformation matrices, SMC for full system is constructed. Also, it is proved that slow subsystem SMC results in a sliding mode motion for full system. Dynamic simulations has been carried out using nodal core model of AHWR to show effectiveness and robustness of proposed method.

2013-08-01T00:00:00Z Munje, R. K. Patre, B. M. Tiwari, A. P. http://localhost:8080/xmlui/handle/123456789/2813 2020-12-02T08:56:49Z 2014-08-01T00:00:00Z

Title: Periodic Output Feedback for Spatial Control of AHWR: A Three-Time-Scale Approach Authors: Munje, R. K.; Patre, B. M.; Tiwari, A. P. Abstract: —This paper presents a novel technique of designing Periodic Output Feedback (POF) based controller for three-timescale systems. This design method is investigated for spatial control of Advanced Heavy Water Reactor (AHWR). The numerically ill-conditioned system of AHWR is first decomposed into three subsystems, namely, slow, fast 1 and fast 2 by direct block-diagonalization and then a composite controller is designed which provides an output injection gain. This output injection gain has been used to compute POF gain, which is then applied to the vectorized nonlinear model of AHWR to achieve spatial control. This controller is tested via simulations carried out under different transient conditions and the results of simulation are presented.

2014-08-01T00:00:00Z Munje, R. K. Patre, B. M. Tiwari, A. P. http://localhost:8080/xmlui/handle/123456789/2812 2020-12-02T08:34:08Z 2013-10-26T00:00:00Z

Title: Non-linear simulation and control of xenon induced oscillations in Advanced Heavy Water Reactor Authors: Munje, R. K.; Patre, B. M.; Tiwari, A. P. Abstract: The physical dimensions and the reactivity feedbacks of Advanced Heavy Water Reactor (AHWR) are such that, it is susceptible to xenon induced spatial oscillations. If these oscillations are not controlled, the power density and the rate of change of power at some locations in the reactor core may exceed their respective thermal limits, resulting into increased chances of fuel failure. Hence, it is essential to suppress xenon oscillations and achieve spatial stabilization of AHWR. Reactor core of AHWR is divided into 17 non-overlapping nodes. Non-linear model of AHWR is characterized by 90 first order differential equations. Total reactor power and 17 nodal powers are output variables. Four voltage signals to the Regulating Rods (RRs) and a feed flow rate are input variables. Applying a highly developed simulation is necessary for analysis and control of spatial oscillations developed in AHWR for safe operation. In this paper, after carrying out stability analysis, a control strategy based on feedback of total power and nodal powers in which RRs are placed is presented for spatial control of AHWR. For the same, a vectorized nonlinear model of AHWR is developed and is implemented in the MatLab/Simulink environment which helps to understand the relationship between different variables of the system in a better way. With the proposed controller, non-linear model of AHWR is simulated and results are generated for different transient conditions. The behavior of delayed neutron precursor and xenon concentrations is also analyzed for each transient. From the simulation results, performance of the proposed controller is found to be satisfactory.

2013-10-26T00:00:00Z