China begins hot functional tests on its small modular reactor ACP100

The first mainland ACP100 small modular reactor is undergoing hot functional tests, after which the operator will load nuclear fuel into it. The fifth unit of the Chinese nuclear power plant is thus moving significantly closer to commercial operation. China officially began construction of the pressurized water reactor, with an installed capacity of 125 MW, in 2021 and aims to bring it online later this year.

Chinese company CNNC (China National Nuclear Corporation) has begun hot functional tests on its first ACP100 demonstration modular reactor at the Changjiang power plant. The small modular pressurized water reactor, also known as Linglong One, has an installed capacity of 125 MW.

Passing hot functional tests is an important milestone for the new nuclear unit before the first nuclear fuel is loaded into the reactor. The tests involve raising the temperature in the reactor cooling circuit and carrying out comprehensive checks to verify that the cooling circuits and safety systems are working as expected.

Planned uses for the ACP100 include not only electricity generation but also heat and steam production, as well as seawater desalination. The unit is expected to generate around 1 TWh of electricity annually. The reactor design incorporates several passive safety systems and can operate for up to 72 hours without human intervention in the event of an accident.

Commissioning within five years

The ACP100 was the first modular reactor to pass a safety review by the International Atomic Energy Agency (IAEA) in 2016.

The Chinese company presented plans for the Changjiang project in 2019 and officially began construction of the demonstration reactor in July 2021. In 2024, CNNC completed construction of the reactor building and commissioned the test control room. Last year, the nuclear unit also successfully completed cold tests.

The planned construction period was originally 58 months (just under 5 years), so it is clear that the first reactor of its kind will be slightly delayed. CNNC is still targeting fuel loading and reactor start-up later this year.