Study on large FBR core optimization to enhance core safety

A design study has been made on high burnup and large sized FBR cores which mitigate the consequences of unprotected accidents. The reactivity feedbacks due to the core radial expansion, the sodium density change and the Doppler effect have significant influence on the maximum coolant temperature in the unprotected loss of flow event. The excess reactivity is also an important parameter for the safety in the unprotected transient over-power event. As the results of sensitivity analysis, a pancake-shaped and low power density core concept is proposed which offers effectively enhanced safety. (author)