Following a 168 hour demonstration run, China’s HTR-PM (high temperature gas cooled pebble bed module) demo facility at the Shidaowan site in Shandong Province has entered commercial operation.

The plant consists of two 250 MWt pebble bed reactors, which provide steam to a single 210 MWe turbine.

The project is owned by a consortium of China Huaneng (47.5%, consortium leader and plant operator), China National Nuclear Corporation subsidiary China Nuclear Engineering Corporation (32.5%, EPC contractor and fuel provider), and the Institute of Nuclear and New Energy Technologies of Tsinghua University (20%, technology leader, with responsibility for main component and systems design). Among main contractors was Shanghai Electric, which supplied reactor pressure vessels, turbines, core internals, control rod drive mechanisms, shutdown systems, primary helium fans and helium compressors.

The Shidaowan facility is the world's first commercial scale modular high temperature gas cooled pebble bed power plant, and first Gen IV facility, to enter commercial operation, and after reaching initial full power and testing the ability to control operations in its “two reactors with one power plant mode", the operators describe it as “laying the foundation for future commercial exploitation.”

Construction started in 2012. The first reactor achieved criticality in September 2021 and the second two months later.

Helium is used as the coolant, and graphite as the moderator. The core of each reactor is loaded with more than 245 000 spherical fuel elements (‘pebbles’), each 60 mm in diameter and containing 7 gm of fuel enriched to 8.5%. Each pebble has an outer layer of graphite and contains about 12 000 four-layer ceramic-coated fuel particles dispersed in a matrix of graphite powder. The fuel has been shown to remain intact, and continue to contain radioactive contents, at temperatures up to 1620°C, which is much higher than the temperatures that could occur even in extreme emergencies,

The HTR-PM project follows China's HTR-10, a 10 MW experimental high-temperature gas-cooled reactor at Tsinghua University's Institute of Nuclear and New Energy Technologies, which went online in 2000 and reached full power in 2003. In addition to operating the HTR-PM, China is developing a larger version, the HTR-PM600, with a single 650 MW turbine powered by six reactors.

Two safety demonstration tests were conducted on the two reactor modules at Shidaowan, each at a power of 200 MWt, on 13 August and 1 September, respectively. Power generation was stopped and the reactors allowed to cool down “naturally”, without human intervention or emergency core cooling systems. The tests confirmed, for the first time at commercial-scale, the “inherent safety” of pebble bed technology.