First AP1000 Nuclear Units Reach Key Milestones

Two Westinghouse AP1000 nuclear power plants being constructed in China have successfully completed significant project milestones.

Sanmen Unit 1—the world’s first AP1000 reactor—achieved initial criticality on June 21. Initial criticality is a nuclear industry term meaning the reactor’s neutron population has remained steady from one generation to the next and the nuclear fission chain reaction is self-sustaining for the first time.

“Today we completed the final major milestone before commercial operation for Westinghouse’s AP1000 nuclear power plant technology,” Westinghouse President and CEO José Emeterio Gutiérrez said in a press release announcing the accomplishment. “We are one step closer to delivering the world’s first AP1000 plant to our customer and the world—with our customers, we will provide our customers in China with safe, reliable and clean energy from Sanmen 1.”

The next significant step is connecting the unit to the electric grid. Assuming work continues on schedule, Sanmen Unit 1 will be the first AP1000 nuclear power plant to commence operation.

Meanwhile, at the Haiyang facility, fuel loading began on Unit 1—another AP1000 reactor. Earlier this summer, in preparation for fuel loading, Haiyang Unit 1 successfully completed testing and regulatory reviews under the watchful eye of China’s National Nuclear Safety Administration. Once fuel is loaded, the plant’s start-up process includes similar steps to those taking place at Sanmen Unit 1 currently.

“The lessons learned and resources shared between Sanmen and Haiyang throughout all phases of construction and start-up have made tremendous improvements in terms of quality and execution, which will benefit future AP1000 fleets,” said Gavin Liu, Westinghouse president—Asia Region. “We will continue to work side by side with our Chinese customers and ensure the success of the remaining testing.”

Westinghouse currently has six AP1000 nuclear units progressing through construction, testing, and start-up. In addition to two units in Sanmen, Zhejiang Province, China, and two units in Haiyang, Shandong Province, China, two units are also under construction at the Alvin W. Vogtle Electric Generating Plant near Waynesboro, Georgia. Work was suspended last year on two additional AP1000 units that had been under construction at the Virgil C. Summer Nuclear Generating Station near Jenkinsville, South Carolina. The Summer project was estimated to be 64% complete at the time. The owners, SCANA Corp. and Santee Cooper, said the decision was based on detailed schedule and cost data analysis, which suggested abandonment of the project would save customers $7 billion.

In May, Georgia Power announced the latest milestones reached at the Vogtle nuclear expansion. It said workers had placed the four main step-up transformers, each weighing 420,000 pounds, inside the Unit 4 transformer bays located near the unit’s turbine building. Teams had also completed a significant concrete placement inside the Unit 4 containment vessel, clearing the path for installation of the unit’s first floor module—CA32.

Other accomplishments at the site included the placement of the second floor module for the Unit 3 operating deck—CA56. That module is part of the steel floor that sits above the in-containment refueling water storage tank (IRWST). The IRWST is a 75,300-cubic-foot tank that, once the units are operational, is filled with borated water and is a key safety feature within containment providing automatic, gravity-fed backup cooling for the reactor vessel.

There were reported to be more than 6,000 construction workers on the Vogtle site at the time. The target in-service dates for Vogtle Units 3 and 4 remain November 2021 and November 2022, respectively.

Aaron Larson, executive editor (@AaronL_Power, @POWERmagazine)