OPG readies for fuel loading at Darlington 2

20 June 2019

Preparations are under way for fuel loading to begin at Ontario Power Generation's (OPG) Darlington 2 which is currently undergoing a mid-life refurbishment - 30 years after the first fuel bundle was loaded into the unit.

New fuel bundles for Darlington 2 (Image: OPG)

With upper and middle feeder tubes already installed and lower feeder installation under way, workers are now practising the complex task of refuelling the unit in the Mock-Up and Training Facility at the Darlington Energy Complex, OPG said. The process will require workers to manually load 6240 new fuel bundles into the actual reactor, in a serialised numbering sequence which is expected to be completed this summer.

"Fuel bundles have been inspected, sequenced and packed by our fuel supplier BWX Technologies, and OPG and CanAtom have been working together, focused on completing the necessary steps to make the reactor whole again," Mike Allen, OPG senior vice president of nuclear refurbishment, said.

Jennifer Noronha, Grant Wetherill, Ken Wilkins and co-workers on site during the 1989 fuel load (Image: OPG)

Darlington 2's first fuel bundle was loaded on 18 June 1989, with the Candu 850 reactor reaching first criticality later that year. The 878 MWe (net) unit operated until October 2016, when it was taken out of service for refurbishment to prepare it for its next 30 years of operation. The reactor was defuelled before being completely disassembled and rebuilt, with thousands of components in 58 interconnected systems to inspected, cleaned and installed. Reassembly was completed in April.

Refurbishment also includes the rehabilitation of steam generators, turbine generators and fuel handing equipment, as well as system improvements and plant upgrades to meet current regulatory requirements.

The reactor is scheduled to be reconnected to the grid in 2020. Work will then begin on a similar refurbishment of unit 3 in February 2020, unit 1 in July 2021 and unit 4 in January 2023.

OPG personnel shared their experiences of the first time fuel was loaded into Darlington 2. Darlington Director of Operations and Maintenance Zar Khansaheb was a newly graduated electrical engineer and had just begun his career when he was participated in the fuel loading, verifying and signing off on fuel bundle serial numbers. The experience was "simply awesome," he said: "It gave me respect for the size of the components and the massive amount of energy they would work together to produce."

Grant Wetherill, now a nuclear operator at Darlington, was part of the first wave of operators-in-training at the new nuclear station. "Thirty years ago, as a young engineer, it was an outstanding experience to be part of the energy and excitement of Darlington commissioning," he said.

Ken Wilkins assisted in loading fuel on each of Darlington's four reactors as they approached commissioning. "Loading fuel into a nuclear reactor is not something everyone gets a chance to do," said Wilkins, who has now returned from retirement to work in training at the plant.

Jennifer Noronha was a commissioning engineer at Darlington working directly on fuel loading in 1989 and now works at Canada's Nuclear Waste Management Organisation. "Thirty years ago, as a young engineer, it was an outstanding experience to be part of the energy and excitement of Darlington commissioning," she said.

The CAD12.8 billion (USD9 billion) project to refurbish Darlington's reactors is scheduled for completion in 2026.

Researched and written by World Nuclear News