Steady-State thermal-hydraulic and neutronic analysis of the NUR research reactor current configuration

Ourida Mokhtari; Lila  Radji

Ourida Mokhtari Division of Nuclear Safety and Radiation Protection, Draria Nuclear Research Center (CRND), Algiers, Algeria
Lila Radji Reactor Division, Draria Nuclear Research Center (CRND), Algiers, Algeria

Keywords: OpenMC, PARET, Clad temperature, NUR research reactor, Steady state, Critical Heat Flux Ratio CHFR, Safety limits

Abstract

Maintaining adherence to safety standards and limitations throughout a nuclear reactor's operational life is crucial to preventing incidents and accidents that could have detrimental effects on workers, the general public, and the environment. The integrity of the fuel, and specifically the first safety barrier (the fuel cladding), must be maintained in order to reduce the likelihood of an accident. Compliance with these limits ensures that even at the hottest point of the reactor core, the safety limits cannot be exceeded. This study provides a thermal-hydraulic and neutronic analysis of the currentconfiguration of the NUR research reactor under steady-state conditions. Its primary aim is to ensure that all the critical thermal-hydraulic parameters uphold margins below the safety limits. The neutronics calculations were performed using OpenMC code validated by the obtained results of WINS/CITVAP ,power density distribution and Power Peaking Factors (PPFs) were calculated. The PPFs for each channel in the core are obtained, and the hot one is then localized. These results were injected in thermal-hydraulic model established by PARET code, in which the core was divided into two regions (two parallel fuel platesand their associated cooling channels). The first region represents the hottest channel in the core, and the second one, the remainder part named the average channel. This model provides the evolution of the fuel, coolant, and cladding temperatures in the hot channel. The temperature profiles generated were compared to those of the asymptotic model of a previous work and those acquired by the TERMIC.1H code in order to validate the PARET model for the reactor core. Consequently, under steady-state conditions, the clad's maximum temperature remained well below the safety limit. The most significant obtained result is that the NUR research reactor can safely operate at a nominal power while staying within the thermal safety limitations.

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