Safety Analysis of 250-kW Philippine Research Reactor-1
Thermal-hydraulics under Steady-state Operations
Using MARS-KS Code

Julius Federico M. Jecong^1,3,4*, Alvie A. Astronomo², Frederick C. Hila¹,
Neil Raymund D. Guillermo¹, and Sweng Woong Woo⁴

¹Applied Physics Research Section; ²Nuclear Reactor Operations Section
Department of Science and Technology–Philippine Nuclear Research Institute
Quezon City, Metro Manila 1101 Philippines

³Nuclear and Quantum Engineering Department
Korea Advanced Institute of Science and Technology
291 Daehak-ro, Yuseong-gu, Daejeon 34141 Republic of Korea

⁴Reactor and Safety Evaluation Department
Korea Institute of Nuclear Safety
62 Gwahak-ro, Yuseong-gu, Daejeon 34142, Republic of Korea

*Corresponding author: jmjecong@pnri.dost.gov.ph

ABSTRACT

The Philippine Nuclear Research Institute (PNRI) of the Department of Science and Technology (DOST) is implementing a project to use the Philippine Research Reactor-1 (PRR-1) TRIGA nuclear fuel in a subcritical reactor (SCR) for training, education, and research in nuclear science and technology. However, although an SCR is a valuable training and research facility, it offers limited industrial applications. To potentially reap more benefits, DOST-PNRI is also investigating the feasibility of converting the zero-power SCR to a low power critical reactor in the future. In this work, the thermal-hydraulic behavior of a hypothetical 250-kW low power configuration of the PRR-1 TRIGA reactor is investigated using the MARS-KS code. At this power level, the fuel centerline or the hottest region of the fuel was determined to have 236.85 °C temperature during steady-state conditions. This temperature is well below the 749.85-°C temperature limit of TRIGA fuel that will result in excessive swelling. The peak heat flux occurs at the axial center of the fuel rod while the calculated departure from nucleate boiling ratio (DNBR) of 6.18 is minimum at this location. Moreover, the maximum fuel temperature is found to be insensitive to variations in coolant velocity, which ranges from 0.20–0.26 m/s within the natural circulation conditions of this facility. Based on the Bernath critical heat flux (CHF) correlation, coolant velocities below 0.2 m/s will still yield a DNBR above 5.0. These results demonstrate that a 250-kW PRR-1 TRIGA reactor operating under steady-state conditions is capable of safely removing the heat generated in the fuel.