Mechanical Shim core operational strategy designed for CPR1000 nuclear power plant

The prime objective of core control is to simultaneously manage core power level and power distribution to ensure the reactor operation safety. In the MSHIM core control strategy in CPR1000, reactor power control includes power level control and power distribution control. Power level control uses the reactivity balance analysis method; the objective of power distribution control is to ensure the safety related parameters, such as DNBRs and FQ within its design limit, AO control analysis method is used. According to the reactivity balance analysis method, the control rods inserted in reactor core to offset the positive reactivity during load follow operation, and in CPR1000 core, part G1-bank is lifted to supply the positive reactivity prior to load follow operation. AO analysis result shows that the axial burnup distribution can affect the AO target value, AO control ability is enhanced with the increase of R-bank worth. Changing burnup history and redesigning the RCCAs are employed.