The first batch of Hualong One fuel assembly units roll off the production line. [Photo/Baotou news network]

The first batch of fuel simulation assembly units were completed on Sept 28 at the recently-completed Hualong One fuel assembly production line operated by China National Nuclear Corporation (CNNC) North Nuclear Fuel Element Co in Baotou.

Hualong One is an advanced million-kilowatt PWR nuclear power technology developed over the course of more than 30 years of nuclear power research, design, manufacturing, construction and operation experience in China. It aims to overcome the problems exposed in the Fukushima nuclear accident and was developed according to the latest safety requirements in China and the world.

This fuel assembly unit relies entirely on independent intellectual property rights in China and is Hualong One's flagship nuclear power product.

The biggest difficulty in the production of fuel assembly parts is the manufacturing of the lower tube socket, which needs to be heated for nearly four hours in a 1000-degree furnace. It needs to raise the temperature to the highest level in sections and has extremely strict requirements in terms of the heating temperature, the holding time and the final sudden cooling.

In addition to production, physical and chemical testing is also crucial. "We use the X-ray imaging principle to check the welding quality of fuel rods online," said Cao Wei, the team leader of the fourth group of NDT room of the CNNC North Physical and Chemical Testing Center.

Tests for this fuel assembly unit are unlike previous tests in terms. Employees read a lot of literature and repeatedly compared the report results to modify the parameters of the testing software. It is reported that on-site technicians can detect 50 to 100 fuel rods a day.