Brazil’s nuclear utility Eletronuclear (part of Eletrobras) expects to complete all the steps required to get approval for extended operation of unit 1 at the Angra NPP. Eletronuclear's Long Term Operations (LTO) programme is designed to enable continued operations at Angra 1 until the end of 2044. The current operating licence is valid to December 2024.

Angra NPP has two operating pressurised water reactors (PWRs) – the 640 MWe Angra 1, supplied by US Westinghouse Electric Company, which was connected to the grid in 1985 and the 1,350 MWe Angra 2, supplied by Siemens, which began operation in 2001. Discussions are ongoing on completion of Angra 3, which was 67% complete when work stopped in 2015 due to the collapse of financial support.

Eletronuclear said it had already undertaken years of preparation towards life extension even before the initial request for renewal of its operating licence was submitted to the National Nuclear Energy Commission (CNEN - Comissào National de Energia Nuclear) in 2019. Westinghouse in 2020 signed a contract with Eletronuclear to conduct engineering analyses critical to the safety, reliability and long-term operation of Angra 1.

In 2023, Eletronuclear submitted 16 reports to the regulatory body, containing, among other things, assessments of the safety factors defined by the International Atomic Energy Agency (IAEA). Based on these, CNEN issued 166 requirements, which were analysed and answered by the technical team of Eletronuclear with support from the Amazul company in April this year.

Eletronuclear has also carried out the third and final Periodic Safety Reassessment (PSR), a document required every 10 years to review safety performance, emergency planning, radiological impact on the environment, management system, safety culture, equipment qualification and the experience of other plants. The PSR was submitted to CNEN in December 2023.

In addition, Eletronuclear also uses the US License Renewal Application (LRA) process, which is administered by the US Nuclear Regulatory Commission (NRC), to demonstrate the ability of Angra 1 to operate for another two decades. The LRA provides a detailed breakdown of reactor safety and integrity through engineering analysis, safety testing and reviews, etc. The material was delivered in October 2019 to CNEN. Two revisions have already been made, and a third is underway.

Eletronuclear is also preparing for a fourth visit in June by an IAEA Safety Aspects of Long Term Operation (SALTO) mission – the previous ones were held in 2013, 2018 and 2022.

“The negotiation process with CNEN should last until the end of this year to finalise the steps,” said José Augusto do Amaral, superintendent of Operational Support Engineering and responsible for the LTO. “But the company is prepared and continues to have constant dialogue ... we are managing to demonstrate that Angra 1 will be able to continue operating efficiently and safely."

According to Eletronuclear, significant advances have already been made to prepare the plant to operate for another 20 years. These include replacement of steam generators, application of weld overlay in the nozzles of the pressuriser, change of the reactor pressure vessel cover and replacement of the main transformers. Some programs were also implemented, such as ageing management, obsolescence management, as well as inspections and maintenance of plant systems, structures and components.

Safety and modernisation projects will be carried out between 2024 and 2028 using investment of BRL3bn ($585m). Eletronuclear said it is negotiating a bridging loan of about BRL 800m with its main shareholders, ENBPar and Eletrobras, to finance the investments already made in 2024 and those still planned in the current year. This is a short-term solution to ensure the extension of the service life of Angra 1, while the company negotiates the financing with US Eximbank for the necessary funding to 2028.

Eletronuclear noted that Angra 1was supplied by Westinghouse on a turnkey basis “which did not provide for technology transfer”. However, “the experience accumulated by Eletronuclear in all these years of commercial operation, with efficiency indicators that exceed that of many similar plants has enabled the company to carry out a continuous technological improvement programme and incorporate the latest advances in the nuclear industry.”

Image: Unit 1 of the Angra nuclear power plant in Brazil (courtesy of Eletronuclear)

Date: Wednesday, 15 May 2024
Original article: neimagazine.com/news/newsangra-1-lifetime-extension-procedures-progressing-11767558