The feasibility of the multi-modular nuclear plant design associated with a multi-modular coordinated control method is verified based on the tests of power ramping, turbine trip and reactor scram carried out on an HTR-PM nuclear plant.
Dr. DONG Zhe | INET news
April 14, 2025
After the Three Mile Island accident, Alvin M. Weinberg, a key founder of the U.S. nuclear energy industry, pointed out in a paper published on Science that safety is the foundation of large-scale nuclear energy utilization. He regarded the practical operation of inherently safe commercial reactors as the hallmark of the second nuclear era, suggesting that integrated pressurized water reactors (PWRs) and modular high-temperature gas-cooled reactors (HTGRs) were the most likely candidates to achieve commercial-scale inherent safety first. On August 23 and September 1, 2023, the Institute of Nuclear and New Energy Technology (INET) of Tsinghua University conducted loss-of-coolant tests on the two reactors of the High Temperature gas-cooled Reactor - Pebble-bed Module (HTR-PM) plant. The test results verify that decay heat can be removed purely by the laws of nature in physics and chemistry without reactor core melting down, marking the first confirmation of the existence of commercial-scale inherently safe nuclear reactors. The related test results were published on July 17, 2024, in Joule, a sister journal of Cell. (Zhang Z, Dong Y, Li F, Huang X, Zheng Y, Dong Z*, Zhang H, Chen Z, Li X. Loss-of-cooling tests to verify inherent safety feature in the world’s first HTR-PM nuclear power plant. Joule, 8: 2146-2159, 2024.)
To ensure inherent safety, the rated power of pebble-bed modular HTGRs is commonly set to be 200 MWt or so. To improve economic viability, it is recommended to adopt the multi-modular scheme for constructing large-scale inherently safe nuclear power plants or cogeneration plants, where multiple standardized reactor modules are interconnected to match the load facilities such as steam turbines with any desired capacities. In 1980s, Germany and the U.S. proposed their multi-modular nuclear plant designs such as the HTR-Module and the MHTGR, but the engineering deployment for verifying the multi-modular scheme has not commenced. As the multiple reactor modules are tightly coupled together by the shared load facilities, multi-modular coordinated control is key in realizing the multi-modular scheme. Although some pioneering works were done by the renowned institutions such as the Massachusetts Institute of Technology (MIT) and the University of Tennessee (UT), the multi-modular coordinated control method is still not proposed and practically applied by these institutions, giving no valuable references for the development of HTR-PM plant.
To meet the urgent needs in design, commissioning, and operation of HTR-PM plant, the INET developed the multi-modular coordinated control method independently and systematically, which was directly applied to develop the coordinated control system (CCS) of HTR-PM plant. The plant-wide test results and the practical operation verify the feasibility of multi-modular scheme, and show that the CCS can provide satisfactory automatic power maintaining and maneuvering control in normal conditions while being able to keep the operational stability in the abnormal scenarios such as the turbine trip and reactor scram. The related test results and coordinated control method were published on March 21, 2025, in Nature Communications, which is recommended by the editor as a featured article. (Dong Z*, Zhang Z*, Dong Y, Shi L, Huang X, Zhu Y, Jiang D. Testing the feasibility of multi-modular design in an HTR-PM nuclear plant. Nature Communications, 16: 2778, 2025.)
Link to the paper: https://www.nature.com/articles/s41467-025-58194-7
https://www.nature.com/collections/fhffefjdca
