Pseudo PIN-by-PIN calculation methodology for PIN power recovery

With the increasing demand of nuclear energy, nuclear energy suppliers are interested in safe and effective margin management in their operations. Moreover, seeking extra financial benefit, the nuclear energy suppliers up-rate their plants, which takes away a lot of original design margin and pushes the fuel and core design very close to the design limits. In such environment, it is more and more important to reduce the uncertainty of the calculations and improve the accuracy of the design codes in both global solution and detailed local distribution such as fuel rod (pin) power predictions so that the reactor capabilities and operation behavior can be precisely predicted and simulated. At the same time, in the new generation PWR core designs such as AP1000(TM), the role of the control rods has been completely changed since the control rods are heavily involved in the core operation. The use of control rods for normal operation has brought significant challenges to the current PWR methodologies. One of the most affected methodologies is the conventional pin power calculation. The insertion of the control rods dramatically changes the heterogeneity of the fuel assemblies, which in turn leads to completely different pin power distribution. The accumulation effect of this re-distribution is a history modeling problem of the conventional pin power recovery methodology since the actual strategy of control rod insertion and withdrawal is not available in advance. Therefore it is difficult to generate pin-wise data at the core design phase to simulate the actual operation condition. The main objective of this PhD research is to develop a novel Pseudo Pin-by-Pin Calculation (P3C) methodology for pin power recovery, which can be directly applied in the Westinghouse core design code ANC. The P3C methodology should be robust enough to simulate all control rod insertion scenarios for all different fuel types and provide accurate pin power predictions. In addition, compared to direct pin-by-pin embedded calculation, this method is more efficient so that the methodology is fast enough to be used in the current code system for routine design calculation and core monitoring. This study focuses on PWR application. However, feasibility study for BWR application is also included.