Optimal control of axial xenon oscillation in PWR based on on-line data processing of axial offsets.

Journal of Nuclear Science and Technology

2009

Self Cite

We have proposed a simplified control procedure for axial xenon oscillations in large PWRs based on a characteristic ellipse trajectory method. However, this procedure cannot guarantee that the desired control rod position can be achieved when the xenon oscillation is terminated. In a previous paper, we proposed an innovative and very simple procedure to generate the trajectory for the predicted oscillation behavior, which can be expressed by trigonometric functions multiplied by an exponential function. By using this prediction capability, it is shown that the optimal control timing can be easily determined to terminate the xenon oscillation at the desired control rod position. The optimal timing is obtained at the intersection or, cross point, of two predicted trajectories, the forward trajectory beginning from the current position and the backward trajectory that is generated based on the desired control rod position. Since the trajectories are calculated by simple trigonometric functions and an exponential function, the prediction takes only a few seconds using a PC.

Section: Procedures Of Optimal Control Timing Searchmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optimal Control Timing Search of Xenon Oscillations in Large PWRs Using a Characteristic Ellipse Trajectory Based on Three Axial Offsets

Journal of Nuclear Science and Technology

2009

Self Cite

“…One important characteristic is that the trajectory is at origin of coordinate, thus AOP=AOX=AOI, if xenon oscillation perfectly stops. 3,4) By monitoring the trajectory, the control action becomes easy to be done. The control rod is moved just to lead the trajectory to the origin of the coordinate.…”

Section: Control Strategy Based On Boron Priority Controlmentioning

confidence: 99%

“…On the other hand, a new procedure based on the three axial offsets trajectory method (TRIAX) has been proved to be ef-fective for xenon oscillation control. [3][4][5][6][7] The method becomes attractive to be used as a control strategy in the load follow operation because of its simplicity and effectiveness. In order to examine the feasibility of application of TRIAX in the load follow operation, we compare this method with the conventional control strategies such as the boron priority control and the control rods priority control.…”

Section: Introductionmentioning

confidence: 99%

Application of Three Axial Offsets Trajectory Method for Load Follow Operation Control in PWRs

Deswandri

Journal of Nuclear Science and Technology

2001

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During load follow operation of PWRs, it is required to control the core power distribution and to reduce the amount of cost due to the usage of control devices such as boron adjustment and control rod. Since occurrence of xenon spatial distribution oscillation following the change of the reactor power can cause oscillation in the power distribution, one task in the core power distribution control is to suppress xenon oscillation as effectively as possible. A lot of studies have been done to solve the problem, some of which use complex mathematical treatments. On the other hand, the three axial offsets trajectory method, which uses a simple mathematical treatment based on two points reactor model, has been proved to be effective for xenon oscillation control. In this study, we examined the feasibility of application of the three axial offsets trajectory method in the load follow operation by comparing with conventional strategies such as boron priority control and control rods priority control. In order to increase the effectiveness of control means, we propose a new method that is constructed by considering the superiority of each control strategy.

“…[1][2][3][4][5][6][7] The characteristics of the oscillation have been well understood and the control procedures are also established, thus xenon oscillations cause no operational difficulties. 6,[8][9][10][11] There are mainly two modes of oscillation; one is axial oscillation and the other one is radial oscillation. It is also known that the latter is convergent and the former can be divergent.…”

Section: Introductionmentioning

confidence: 99%

Xenon Oscillation Control in Large PWRs Using a Characteristic Ellipse Trajectory Drawn by Three Axial Offsets

2008

J. Nucl. Sci. Technol.

Self Cite

We have proposed a very simple xenon oscillation control procedure for axial xenon oscillation control based on a characteristic trajectory. The trajectory is drawn by three offsets of power distributions, namely, AOp, AOi, and AOx, which are defined as the axial offset (AO) of power distribution, AO of power distribution under which the current iodine distribution is obtained as the equilibrium, and that for xenon distribution, respectively. When these offsets are plotted on the X-Y plane for (AOp À AOx, AOi À AOx) the trajectory shows a quite characteristic ellipse (or an elliptic spiral). When the plot is at the origin of the X-Y plane, no xenon oscillation exists. Using the characteristics of the ellipse, the xenon oscillation can be eliminated by guiding the plot to the origin with control rod operation. In this paper, we will present an innovative and very simple procedure to generate the trajectory for the prediction of the oscillation behavior. Using the prediction capability of the xenon oscillation, the optimal control search calculation can be done. Since it is calculated by simple trigonometric functions and an exponential function, the prediction takes less than 1 s with a PC. It is especially effective for radial xenon oscillation control when the control rod motion is not flexible as for axial xenon oscillation control.