Hot functional tests involve a comprehensive check of all systems and equipment before the reactor goes critical. In fact, this is the last check before nuclear fuel is loaded into the reactor core. During hot functional testing, all engineering and process control systems of the unit and nuclear plant are verified to be functioning as designed. According to the official statement, engineers will run more than 100 tests to be completed within 54 days. This will be followed by an inspection of key equipment components. As soon as China’s regulator issues an operating license, Unit 3 will be loaded with fresh nuclear fuel. Tianwan Unit 3 is expected to go critical later this year, with commercial operation scheduled to begin in 2018.