PLANT LIFE EXTENSION | GOING BEYOND 40
Digital innovations supporting LTO Several innovations from software to artificial intelligence (AI) and robotics are being used to support life extensions programmes at nuclear plants. AI can be particularly useful in documentation and safety case preparation, as well as for condition-based predictive maintenance. “With AI tools, you can really speed up that documentation side of things,” says Wolvaardt, noting that for engineering design modification the design work typically takes 30% of the time, with the other 70% spent producing necessary documents. Several original equipment manufacturers have now put their entire nuclear knowledge base on generative AI platforms, including licensing/design documentation and procedures and processes. In the US, Pacific Gas and Electric Company (PG&E) used a generative AI platform from Atomic Canyon to accelerate document search and retrieval to support licence extension at Diablo Canyon (two 1138 MWe Westinghouse PWRs) in California. Wolvaardt sees opportunities to leverage generative AI tools further, potentially as part of the SALTO process. However, he stresses the continued importance of human oversight throughout the life extension process. Speaking more broadly, Eskom told NEi that digital tools are supporting asset management and decision making
as part of the LTO effort at Koeberg in South Africa. For example, databases were created to track monitoring of electrical cabling, for managing degradation of components and to analyse the radiation effects on the reactor pressure vessel and its materials. Eskom has also implemented a fibre optic containment monitoring system to measure real-time mechanical behaviour of the Koeberg’s two containment buildings. Fortum says innovations at Loviisa include using drones for visual inspection of critical main components and robots for steam generator (SG) maintenance. An inspection and cleaning robot co-created by Fortum and Finland’s Jyväskylä University of Applied Sciences (JAMK) was found to significantly improve worker safety by reducing the work done inside the SGs. Innovative new tooling and technology has also been implemented across CANDU refurbishment projects in Canada and elsewhere. The Bruce 3 MCR pioneered use of the first robotic tooling used on a reactor face anywhere in the world, supporting safe, successful and on schedule return of the unit in 2026.
Hungary, Sweden, Romania, South Africa, South Korea and the UK are also among countries seeking life extensions across a range of reactor types.
Two main pathways to life extension Internationally, there are typically two models for achieving plant life extension, explains Dr Derik Wolvaardt, senior executive at Lesedi Nuclear Services, a South African engineering, procurement and construction (EPC) company involved in supporting life extension works at Koeberg as well as internationally. The US NRC’s License Renewal Rule (10 CFR Part 54) defines a robust programme of evaluation and assessment needed to apply for a renewed licence; it can be applied multiple times, provided each renewal satisfies safety requirements. Outside of the US, utilities typically follow the IAEA Safety Aspects of Long-Term Operation (SALTO) process, an approach that is less prescriptive. The SALTO service provides advice and assistance to countries considering extending the operating lives of their nuclear plants. Since 2005 it has offered peer reviews to compare LTO activities against IAEA Safety Standards and international good practice. The expert review process typically involves:
A workshop on the IAEA Safety Standards and the SALTO review methodology
A nine-day pre-SALTO mission (anywhere from 10 to two years before LTO)
The SALTO mission (less than two years before LTO)
A follow-up mission (1.5-2 years after the pre-SALTO and SALTO review)
Case study: Koeberg looks to life beyond 40 Africa’s only commercially-operating nuclear plant, Koeberg, took part in the SALTO process. Wolvaardt says that Lesedi was involved in the work at Koeberg, utilising software tools to conduct ageing analysis. “We started with hundreds of thousands of SSCs in the scoping and screening process. After that process, we ended
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up with about 80,000 safety-related components for the two Koeberg units (pumps, civil structures, cables, etc.),” he explains. These components were then screened and put into ‘commodity groupings’ based on their materials, environmental and other common properties. Each of the commodity groupings – and some of the larger individual components – then underwent further analysis to determine whether they can achieve a life span beyond 40 years. Lesedi also supported component upgrades at Koeberg, including replacement of the refuelling water storage tanks (RWSTs), the reactor pressure vessel heads and the steam generators (SGs). Eskom explains that the SALTO review in March 2022
and its follow-up mission in September 2024, focused on aspects essential to safe long-term operation, “in particular ageing-management programmes, certain equipment- condition issues (including cable management and corrosion monitoring), and enhancements to plant-wide monitoring and safety oversight”. Koeberg 1 received a licence to continue operating until 2044 in July 2024 and Eskom is planning to extend operations of Koeberg 2 until 2045. Koeberg 2’s operating licence runs until 9 November 2025. Eskom has applied for LTO. South Africa’s nuclear regulator plans to hold public hearings on the application in the autumn and will announce its decision before the current licence expires.
The outlook for life extension Nuclear life extension is an essential part of meeting net-zero ambitions. Momentum for nuclear power continues to build. The IAEA forecasts global nuclear capacity growing from 377 GWe in 2024 to 561-992 GWe by 2050. In the ‘high-case’ scenario most current reactors would receive life extensions, limiting retirements to 20% by mid-century. Established frameworks and technology demonstrate that
existing units can support safe operation beyond 40 years. However, the challenge will be maintaining public confidence and political will alongside engineering progress. ■
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