Cask Loading Performances: Combined Data Mining and Shielding Inequalities

The latest IAEA recommendations (2012, SSR-6) request that, under routine conditions of transport, shielding analyses take into account loading plans with the maximum radioactive contents. In parallel, storage’s regulators request now to define generic loading plans. Thus, cask designers are facing a challenge to implement a method defining maximum generic loading plans without restrictions on new cask design or cask license renewal. In order to avoid unnecessary restrictions of the authorized content characteristics while still meeting the new requirements, Orano TN has adapted its licensing process and developed a very elaborated shielding analysis method. The result of this method, part of certificates, is expressed under the shape of a linear inequalities system allowing to optimize efficiently the cask capacity by normalizing with reference loadings while still meeting the radiation criteria. Major advantages of this approach include the following: dose rate calculation is not required at each loading; it provides a high loading flexibility for the customers. In the frame of the design approval of the dual purpose TN®24 E package by the German authorities (BfE, TÜV) this method has been validated. Furthermore, in the frame of the design approval of the transport casks TN®G3 and TN®17 MAX, and in the frame of the license renewals of the TN®24 BH, TN®24 SH, TN®24 DH, TN®24 XLH and TN®9-4 package, this method has been also implemented and validated by the French authorities (ASN, IRSN).The so determined linear inequalities system ensures the transport acceptance of any radioactive content regarding the regulation and allows using highly heterogeneous loading plans. The use of this validated method is decisive to give the cask user the maximum flexibility for an optimized management of its cask loading plans on the long term. Indeed, using algorithms from data science, an optimization analysis of the cask loading plan solutions can be performed in order to get well-defined “best loading plan”. These solutions must maximize the total residual thermal loaded and in parallel minimize the radiation levels around the cask.This paper will describe the approach and the tool developed by Orano TN and its positive outcomes.