ENUN Cask: A success history

The purpose of this presentation will be to explain the history of the ENUN dual-purpose bare-fuel type cask series from the conception until the first recent loadings, together with an update on the current design status and manufacturing process improvements.After the design of the former ENSA-DPT cask in the 90’s and the HI-EN collaborative cask design, Ensa started a new cask project to improve the performance and reduce the production costs of the casks, in order to provide Spanish NPPs with an improved and customized solution adapted the country’s actual spent fuel management strategy: the ENUN cask series. New materials, state-of-the-art calculation methodologies and improved manufacturing processes were studied in order to increase the competitiveness of the cask. This design process led to the submittal of the first revisions of the Safety Analysis Reports of the ENUN 32P to the Spanish nuclear authority in 2011. Shortly after, a smaller and customized BWR version of the ENUN cask was designed for Santa María de Garoña NPP, whose license was obtained in November 2014 for Storage and in June 2015 for transportation. In parallel, a Chinese transportation version of the ENUN 32P cask was designed for the Chinese market and licensed both in Spain and China in July 2017 and in April 2018 respectively.After years of work, finally three ENUN 32P casks have been successfully loaded in Trillo and Almaraz NPP’s in Spain in December 2018. Lessons learned directly related with these loadings include the composition of the anticorrosion protective coating in the inner surface of the casks and an update of the pressure transducer design for higher temperatures.Currently, Ensa is also involved in design modifications to increase the capabilities of the ENUN casks, new materials and manufacturing processes, so that the overall production process can be improved in terms of time and cost. Also, ENSA is now implementing the Building Information Modeling methodology to study the manufacturing flow (4D planning) for expected large series of new units of ENUN casks needed from the NPPs and the potential collisions with other large nuclear component being manufactured at ENSA’s facility.