Brazil’s nuclear utility, Eletronuclear (part of Eletrobras) has announced completion of the first phase of a second campaign to transfer used nuclear fuel from unit 2 of the Angra NPP to the Irradiated Fuel Dry Supplementary Storage Unit (UAS – Unidade de Armazenamento Complementar a Seco de Combustível Irradiado). The work, which began on 26 April, saw 480 used fuel elements transferred from Angra 2 to the UAS, located inside the Almirante Alvaro Alberto Nuclear Power Plant (CNAAA – Central Nuclear Almirante Álvaro Alberto). The second phase, planned for 2025-2026, will focus on Angra 1.
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.
The UAS dry storage includes physical security, radiation and temperature monitoring, an armoured access control centre and a storage warehouse with a technical workshop, designed and constructed by US Holtec International under a turnkey contract signed in 2017. The facility was required because the storage pools of Angra 1&2 were reaching full capacity.
The Holtec International Storage Module Flood and Wind (HI-STORM FW) system consists of interchangeable sealed multi-purpose canisters (MPCs), which contain the fuel; a vertically ventilated storage overpack constructed from a combination of steel and concrete which protects the MPC during storage; and a variable weight transfer cask (HI-TRAC VW), which contains the MPC during loading, unloading, and transfer operations.
The UAS is designed to hold 72 Hi-Storm canisters, with capacity to receive used fuels until 2045. As Angra 1&2 have different architectures and licensing bases, Holtec modified the cask handling cranes and equipment as appropriate for each unit.
The first campaign, which took place between 2021 and 2022 resulted in 15 Hi-Storm canisters being transferred to storage. The first phase of the second campaign saw 15 more transferred. At the end of the present campaign, following work at Angra 1, a total of 48 Hi-Storms will be in storage.
