Optimization of Boiling Water Reactor Control Rod Patterns Using Linear Search

A computer program for searching the optimal control rod pattern has been developed. The program is able to find a control rod pattern where the resulting power distribution is optimal in the sense that it is the closest to the desired power distribution, and it satisfies all operational constraints. The search procedure consists of iterative uses of two steps:

1. sensitivity analyses of local power and thermal margins using a three-dimensional reactor simulator for a simplified prediction model
2. linear search for the optimal control rod pattern with the simplified model.

The optimal control rod pattern is found along the direction where the performance index gradient is the steepest. This program has been verified to find the optimal control rod pattern through simulations using operational data from the Oyster Creek Reactor.