Developing a practical optimization of the refueling program for ordinary research reactors using a modified simulated annealing method

• Introducing and developing a practical fuel management optimization.
• Fundamental concepts, design criteria and safety issues are introduced coherently.
• The most numbers of core and safety parameters have been influenced.
• High reliable and stepwise core modeling in criterion space.
• High optimizing abilities and performances.

Each core configuration of a research reactor can be optimized to provide particular or general multi-purpose irradiating conditions; specially, it includes refueling cycle length and irradiating neutron fluxes if a core management is limited to a refueling task. Each practical core or fuel management operation needs providing all of related Operational Limits and safety Conditions (OLCs). In this paper refueling cycle length and maximum irradiating thermal neutron flux are chosen as the optimizing objectives; also OLCs including total Power Peaking Factor, Shutdown Margin, Reactivity Safety Factor (RSF), and maximum permissible core excess reactivity are influenced as optimizing constraints. All parameters have been calculated accurately and benchmarked against operational parameters of a 5 MW MTR. Primary 2-D annealing process is following up to a secondary re-annealing in fine 3-D calculations. This expands global search space while the required time is reduced. Safety margins are introduced by stepwise penalty functions instead of a direct rejecting method. Results are very promising, required iterations are decreased; safety faults are automatically removed, and final results are gained near touch the infeasible frontier formed by safety margins. Refueling cycle length is significantly increased, averaged and maximum irradiating neutron fluxes are enhanced while selected OLCs are passed.