Breeding Blanket Remote Maintenance Concepts in EU DEMO: From vertical extraction to horizontal accommodation in cask

Abstract

During the lifetime of a magnetic confinement nuclear fusion reactor, the replacement and decommissioning of Breeding Blankets (BB) are anticipated operations that occur in the upper-level containment cell of a reactor building, such as EU DEMO. Such operations are not feasible by in-situ human interaction. Remote Handling (RH) is the leading solution in the nuclear industry for addressing these operations. The BB is a structure with approximately 13 metres in length and weights between 100 and 120 tons. The BB is assumed to be extracted vertically and transported horizontally by casks to the Active Maintenance Facility. The BB is divided into 5 different segments for maintenance purposes: 2 inboard and 3 outboard segments. Both inboard and outboard segments pose different handling and rotation challenges. Three design concepts for handling/rotating (H/R) BB segments are proposed in this study. The concepts rely on variations of the Medium Payload Manipulation Stillage (MPMS), a system responsible for securing and H/R the BB segments. The concepts are: (I) Crane Support Concept (heavily relies on a crane to perform the rotation of BB segments), (II) Lifting Platform Support Concept (only relies on the MPMS itself to perform the rotation of the BB segments), and (III) Sliding Platform Support Concept (only relies on the MPMS itself to perform the rotation of the BB segments but provides additional support and makes use of gravity to its advantage). A comparative analysis highlighting the concept’s advantages and disadvantages is presented. The analysis and conclusions presented in this paper are derived from the assessed system requirements, possible risks concerning the CAD model designs, expected sequence of operations performed by the MPMS and the dimensions of the systems depicted in the CAD models.