Construction of Linear Empirical Core Models for Pressurized Water Reactor In-Core Fuel Management

An empirical core model construction procedure for pressurized water reactor (PWR) in-core fuel management problems is presented that (a) incorporates the effect of composition changes in all the control zones in the core on a given fuel assembly, (b) is valid at all times during the cycle for a given range of control variables, (c) allows determining the optimal beginning of cycle (BOC) k_∞ distribution as a single linear programming problem, and (d) provides flexibility in the choice of the material zones to describe core composition. Although the modeling procedure assumes zero BOC burnup, the predicted optimal k_∞ profiles are also applicable to reload cores. In model construction, assembly power fractions and burnup increments during the cycle are regarded as the state (i.e., dependent) variables. Zone enrichments are the control (i.e., independent) variables. The model construction procedure is validated and implemented for the initial core of a PWR to determine the optimal BOC k_∞ profiles for two three-zone scatter loading schemes. The predicted BOC k_∞ profiles agree with the results of other investigators obtained by different modeling techniques.