Conceptual analyses of equilibrium conditions to determine a long-term fuel management strategy for research reactors

• Developing a practical fuel management strategy for the usual research reactors.
• Fundamental concepts, design criteria and safety issues are introduced coherently.
• Simplified models and fast calculations of a long-term fuel management strategy.
• Results are in accordance with the operating conditions and parameters.
• Required calculating and consideration time is reduced significantly.

We present conceptual analyses of equilibrium conditions for research reactors to determine periodic and long-term requirements for a practical fuel management strategy (FMS). The MTR-PC package developed for research reactors is used for FMS simulation. A baseline is calculated and is in satisfactory agreement with previous calculations and the operating state of the Tehran research reactor. Fundamental concepts, design criteria, and safety issues for research reactors are discussed for development of a practical FMS. Fast calculations and simplified models of an operational FMS are considered before final planning and simulation. This includes pre-estimation of the fuel assemblies required, fast FMS simulation assuming ideal equilibrium conditions, and verification of operating safety limits and conditions. Semi-equilibrium behavior due to a partial refueling task and equilibrium reflexes for the core parameters are also studied. The results show that the simplified models and methods are in accordance with the operating states and conditions.