Canada targets higher nuclear returns, longer lifespans at new test facility

Canada's new reactor research center will use advanced inspection technologies and micro materials testing to improve maintenance and ageing management programs, industry experts told Nuclear Energy Insider.

Last month, Canadian Nuclear Laboratories (CNL) launched a new Centre for Reactor Sustainability (CRS) to support the long-term operation of nuclear power plants.

The new facility will help nuclear operators minimize operational costs and build the business and safety cases for longer lifespans. In North America and Europe, operators are looking to maximize returns on existing assets in the face of wholesale price pressure and rising new build costs.

CNL will use the CRS to develop innovative technologies and inspection services that improve plant reliability. Priority research areas include ageing management and specialized inspection and maintenance tooling.

The center will build upon decades of CNL research that has allowed operators like Bruce Power maximize returns on investments.

Bruce Power operates eight Canada deuterium uranium (Candu) reactors for a total capacity of 6.4 GW at its site north-west of Toronto. In 2015, the company announced a CA$13 billion 15-year refurbishment program to extend the lifespans of six reactors by 30 to 35 years.

In September, the Canadian Nuclear Safety Commission (CNSC) approved a 10-year licence extension for the facility.

CNL research was instrumental in the approval process, providing innovations such as a bespoke maintenance tool to move tight-fitting urn springs, Len Clewett, Chief Nuclear Officer of Bruce Power, told Nuclear Energy Insider.

“Without that tool, which was highly technical work started at CNL, Unit 8 would have shut down in 2018-19…we now expect to operate Unit 8 until 2028,” he said.

Ontario nuclear power refurbishment schedule                             

                                (Click image to enlarge)

Source: Ontario government's Long-Term Energy Plan (July 2018)

Predicting faults

New inspection processes developed at the CRS will support proactive intervention and reduce inspection times, minimizing lost revenues and maintenance costs.

Bruce Power hails CNL’s previous advances in identifying seal degradation.

“CNL has unique expertise in primary heat transport seal components," Gary Newman, Bruce Power’s Vice President of Engineering, said.

CNL can do a "full evaluation” of these components, he said.

CRS researchers are now developing specialized methods of non-destructive examination, initially focusing on eddy current techniques. These processes are currently being performed on steam generators, to identity any cracking, fretting wear, pitting, or chemical corrosion on the component surface, Lori Walters, CNL’s Senior Mechanical, R&D at CNL, told New Energy Update.

The teams will also develop ultrasonic methods for reactor components and remote visual inspections.

U.S. nuclear researchers have also made significant advancements in NDE techniques. For example, the Electric Power Research Institute (EPRI) and industry partners are combining the latest robotics and probe designs with high sensitivity NDE techniques to inspect dry cask storage systems (DCSS).

Four of these NDE techniques --Visual (VT), eddy current testing, ultrasonic testing and EMAT/Guided Waves (GW)-- have already met requirements on temperature and radiation resistance, sensitivity, compatibility for DCSS inspection, and short-term deliverability, Jeremy Renshaw, Program Manager - Used Fuel and High-Level Waste at the Electric Power Research Institute (EPRI), said in October.

"We are ready to go with a capable technique that fits the application needs," he said.

Researchers are also using advanced analytics programs to increase the accuracy and shorten the duration of inspection programs.

Ageing management

Accurate performance predictions require comprehensive monitoring of the ageing of components.

CNL's current ageing management research includes innovative techniques in material characterization, Gina Strati, Program Director, Energy at CNL, told New Energy Update.

For example, research teams are monitoring crack initiation and development to understand material degradation in steam generators, Strati said.

A better understanding of material degradation allows operators to optimize repair schedules and develop mitigation solutions.

“Chemistry control of the steam generators is required to maintain material integrity. This is achieved by maintaining a high pH and maintaining oxygen at a very low concentration,” Walters said.

CNL adds hydrazine (an oxygen scavenger) and ammonia or morpholine to maintain pH, he said.

Other key areas include the monitoring of corrosion products in plant feed water to limit material degradation and reduce the transport of these products into the steam generators, Walters said.

Micro testing

CNL hosts hot cell facilities at its Chalk River Laboratories facility, making it Canada's main test center for post-irradiated materials.

CNL has recently developed micro-mechanical testing capabilities for these materials, Strati said.

CNL is able to obtain mechanical properties from samples which are around 1,000 times smaller than standard small-size specimens, reducing material requirements and minimizing waste, she said.

Bruce Power already relies on CNL for the bulk of its post-irradiated material testing, including spent fuel. CNL’s testing of fuel bundles provides fuel integrity data which helps to improve future plant performance.

“We’ve added decades of life to our operating units through the work CNL has done,” Clewett said.

Going forward, CNL will play a “key role” in Bruce Power’s projects to monitor component performance and extend the lifespan of its plants, he said.

By Jax Jacobsen