Best estimate analysis of Monticello plant transients using DYNODE-B

The DYNODE-B code has been used to simulate operational transients which have occurred at the Monticello Nuclear Generation Plant in Monticello, Minnesota. For the case of a complete isolation of all main steam lines during full power operation, DYNODE-B has been used to help identify the cause of an unexpected response in system pressure which delayed the opening of the safety/relief valves until much later than had previously been expected. It is shown that the DYNODE-B model of a BWR system can be used to realistically model the response of such a system to transient conditions. The use of DYNODE-B to support plant operations by analyzing unexpected system responses and evaluating their possible causes is also demonstrated. These calculations provide documentation in support of the use of DYNODE-B for best- estimate analysis