BRIN and UI Successfully Develop Innovative PRHR System to Improve Nuclear Reactor Safety

Yogyakarta - Both developed an innovative Passive Residual Heat Removal (PRHR) system based on two-phase thermosiphon technology, which will improve the safety of nuclear reactors. This system is designed to improve the efficiency of passive heat removal in a 300 MW thermal light water reactor (LWR).

"The main objective of this research is to study the performance of two-phase thermosiphons in the PRHR steam environment, as well as to assess their effectiveness in extracting heat directly from the steam generator. So that it can reduce the size of the heat exchange equipment needed," explained Anhar Riza Antariksawan, BRIN Principal Researcher who is also a lecturer at the Indonesian Nuclear Technology Polytechnic (Poltek Nuklir) Yogyakarta, in a written statement, Friday (20/4/2025).

Conventional PRHR systems are generally only able to work effectively for 72 hours after the reactor is shut down, without operator intervention. In prolonged emergency conditions such as the Fukushima Dai-ichi nuclear power plant incident, this system becomes inadequate. Therefore, the BRIN and UI research team offers a solution based on two-phase thermosiphons that work without external electricity and have high heat transfer efficiency.

The main advantage of this system lies in the placement of the thermosyphon evaporator directly in the PRHR steam path, allowing efficient latent heat transfer.

"This is an important step in improving the safety and reliability of passive cooling systems for advanced reactors," he added.

This innovation is also designed to reduce the size and complexity of additional heat exchange systems. The system works in two modes: using water for the first three days, and air thereafter, allowing autonomous operation during prolonged cooling. This adaptive design is considered very relevant for future reactors that prioritize passive safety.

Anhar said that this research was carried out through experimental testing using the Passive System Condensation Experimental Loop (PASCONEL) and numerical validation with RELAP5 software. The results show that one thermosyphon tube unit is capable of removing up to 5 kW of heat. To maintain the reactor's safety passively after 72 hours, it is estimated that around 60 thermosyphon units are needed.

"The next step is to characterize the heat transfer on the condenser side using air as a cooling medium, in order to increase thermal efficiency," said Anhar.

In addition to Anhar, the research team also consists of Surip Widodo (BRIN and UI), Nandy Putra (UI), and Mulya Juarsa (BRIN). This research marks an important milestone in the progress of reactor safety by integrating experimental research and numerical simulations.

Through synergy between national research institutions and academics, BRIN confirms its commitment to presenting innovative solutions to answer global challenges in the field of safe, efficient, and sustainable nuclear energy.

Nuclear research in Indonesia has been started since the 1950s and currently has three research reactors, namely the Kartini Reactor in Yogyakarta, the Triga Reactor in Bandung, and the G.A. Siwabessy Multipurpose Reactor in Serpong. Currently, Indonesia's nuclear ambitions continue to grow with a focus on developing nuclear power plants in the next few years. (Red)

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