Silo Storage for IVG.1M Irradiated HEU

The National Nuclear Center of the Republic of Kazakhstan’s IVG.1M reactor was commissioned in 1975 with a thermal neutron flux of 3.5 × 1014 (n/cm2)/s and peak power of 72 MW when operated. The original fuel assemblies contained 90 wt % 235Uranium. The irradiated fuel assemblies were removed from the core in March 2022. In accordance with the US–Russia government-to-government agreement, the irradiated highly enriched uranium (HEU) fuel from the IVG.1M reactor was supposed to be sent to Russia for processing and downblending in 2023–2024. However, in February 2022, the US National Nuclear Security Administration (NNSA) suspended all work for the IVG.1M fuel shipment due to Russia’s expanded invasion of Ukraine. NNSA and National Nuclear Center of Kazakhstan (NNC) worked to evaluate different options for interim storage of the fuel until its final disposition can be determined. Three dry-storage technology options were considered based on their ability to meet all Kazakhstan regulatory and functional requirements within a reasonable cost and schedule: vertical silo storage, dual-use cask storage, and a near-reactor storage well. A feasibility study was performed with each option evaluated by a committee of technical experts using criteria they had selected and prioritized. Vertical silo storage was determined to be the best option for the long-term temporary storage because of its enhanced security, lower cost, and ease of implementation, and this option was presented to the Ministry of Energy of the Republic of Kazakhstan, where it was approved in January 2023. NNSA is currently working with NNC to implement this storage option.