Control rods effect analyses on thermo-hydraulic safety parameters in TRR

Abstract

In this study, the effect of control rods on TRR safety parameters was investigated in both cases of static and transient behavior. In this paper, the effect of the control rods movements (70%) on the power peaking was used in the form of the normalized function instead of the COS function in the TERMIC cod. The results of the new function were investigated on thermo-hydraulic parameters in the steady-state and transient conditions. In the steady-state with 5 MW thermal power, the results showed that the safety margin in new condition (70% insertion) decreased respect to the state that all control rods where out. Also, in the transient section, the axial function of the power distribution was applied in the input of the PARET cod. The direct influence of control rods on the power peaking was the production of nucleate boiling earlier than the COS shape function. This effect, reduced the power and temperatures due to the void coefficient feedback. In the last section, the effect of the control rods insertion on the reactivity feedback coefficient was considered in the transient scenario. Increment of the reactivity feedback coefficient due to control rods insertion along with the direct effect of control rods caused a significant decrease in all thermo-hydraulic safety parameters.

Keywords

• research reactors
• thermo-hydraulic
• transient behaviors
• safety parameters