The Douglas Point Nuclear Generating Station was Canada’s first full-scale nuclear power plant, home to the 200-megawatt CANDU™ prototype reactor that ran from 1967 to 1984
Chalk River Laboratories materials scientists teamed up with the decommissioning team at Canada’s first full-scale CANDU™ power plant — the Douglas Point Nuclear Generating Station —to further their research examining how a “non-refurbishable” CANDU™ reactor core component degrades over time.
Called the calandria vessel, this component is a large, cylindrical vessel containing the reactor core’s 400 to 500 fuel channels and heavy water moderator. Like other reactor core components, the calandria vessel receives radiation-induced damage that, over time, can accumulate and affect the properties and performance of the vessel, made of austenitic stainless steel.
But, unlike other reactor core components, the calandria vessel cannot be refurbished for logistical, technical, and cost-efficiency reasons. Therefore, these components must remain fit for service beyond their original design’s expectation of 60 effective full power years by another 40, as per the federal government’s decision to extend the current reactor fleet’s lifetime.
Last fall, researchers leveraged surrogate material from the National Research Universal (NRU) reactor that had undergone near identical conditions a CANDU™ calandria vessel would have to get an understanding of how radiation affected this material. At that time, there was no ex-service CANDU™ calandria material available to study.
However, that changed earlier this year, when researchers paired up with CNL’s reactor segmentation decommissioning group working at the Douglas Point Nuclear Generating Station, which is home to the 200-megawatt CANDU™ prototype reactor that ran from 1967 to 1984.
Footage of the fuel channels and the calandria vessel face inside the Douglas Point reactor
The decommissioning team had been in the process of collecting and characterizing materials from the reactor as part of their clean-up mission, with those collected materials destined to become radiological waste.
Now having partnered with researchers from science and technology, the collected materials will instead be archived in an ex-service materials “library” that can be used for research and development supporting both reactor long-term operation and reactor decommissioning.
These samples include one harvested from Douglas Point’s calandria vessel, which is now the only known sample of ex-service CANDU™ calandria vessel material made available for research.
This sample and the team’s work ahead is a first of its kind in Canada.
Their efforts will provide in-depth, realistic insights needed to assess and understand how non-refurbishable calandria vessels are performing in refurbished reactors and support larger decommissioning projects.
This research is funded by Atomic Energy of Canada Limited’s (AECL) Federal Nuclear Science & Technology (FNST) Work Plan, which connects federal organizations, departments, and agencies to the nuclear science expertise and facilities we have at Chalk River Laboratories.
Under the FNST Work Plan, our researchers carry out projects designed to support the Canadian government’s core responsibilities and priorities across the areas of health, safety and security, energy, and the environment.
