Cold critical calculations on the WNP-2 BWR

Comparisons of cold critical calculations with measurements have been performed at Washington Public Power Supply System to verify that the model used for reactivity calculations for its operating boiling water reactor, WNP-2, are reasonable. This model utilizes cross sections obtained from the CPM lattice physics code in the SIMULATE light water reactor nodal core analysis computer program. The model is used to determine estimated critical control rod positions, control rod notch worths, and shutdown margin. Washington Public Power Supply System is using Electric Power Research Institute supplied computer codes to perform analysis on its operating boiling water reactor. Two calculational models have been developed for core follow. One model, which is called the hot model, calculates reactor conditions in the operating power range and determines the three-dimensional power distribution including the effects of hydraulics, control systems, and fuel depletion. The second model, which is called the cold model, calculates the reactor core conditions in the cold or heatup range and determines the effective multiplication factor, k, taking into account the effects of control systems and fuel depletion. The fuel depletion information is passed from the hot model to the cold model in a three-dimensional nodal basis. A comparison between the effective multiplication factor calculated by the cold model and the measured critical is discussed