267- Developing an Unloading Strategy Following NPP Shut Down: Example of Doel 1&2

Since the Doel 1&2 nuclear power plant shutdown announcement in Belgium, planned for 2015, Synatom has had the challenge of emptying the deactivation pond with an optimized schedule. Reprocessing was the reference strategy for the used fuel management of Doel 1& 2 until 1993. After a debate in Parliament in late 1993 putting the reprocessing option on hold for 5 years ,the used fuel of Doel 1&2 was stored in TN® 24 SH casks in the interim storage building SCG on the site. On January 1, 2013, 25 TN® 24 SH were already in storage, and six other ordered casks had to be delivered. In order to keep the post-shutdown period as short as possible, Synatom put in place an efficient spent fuel management strategy: TN International conducted a feasibility study to unload the pond of Doel 1&2 with the existing TN® 24 cask SH in a maximum period of 3 years after shutdown. The aim of those studies was to demonstrate the feasibility of the operation and to optimize the capacity of the cask in terms of fuel characteristics (in particular the possibility to unload fuel assemblies with short cooling time). Analyses were based on data of fuel currently in ponds and planned to be unloaded until final shutdown. Constraints on the duration of the on-site loading and transfer operation were considered, for example, the number of days for a complete loading cycle. First, TN International assessed each fuel family in terms of thermal power and sources to optimize the proposed loading plans. Secondly, based on thermal and radiological numerical calculations, 5 partial heterogeneous TN® 24 SH loading plans to unload the pond in 3 years after the definitive plant shutdown have been proposed. These loading plans respect all transport criteria of the applicable Certificate of Compliance as well as the relevant storage criteria. Methodologies developed by TN International enable the rapid optimization of these loading plans in case of modification of data such as fuel characteristics, hypothesis of cooling time, schedule of operations… The purpose of the paper is to describe this global approach and its benefits.