The CIEMAT LiPb Loop Permeation Experiment

Abstract

A new facility, CLIPPER, is being constructed at CIEMAT to investigate tritium extraction from PbLi. It consists in a forced circulation loop with the main objective of validating the technique of permeation against vacuum. Originally, CLIPPER was designed with two zones operating at different temperatures and connected through a recuperator, which gives most of the required thermal jump. In the cold leg the PbLi circulated at 300 ºC to have the PbLi in liquid phase, but high enough for avoiding cold points. The hot leg would increase PbLi temperature up to the experimental necessities (500 ºC). After a careful evaluation of the preliminary design, and considering the limitations of the laboratory in terms of power and available space, it was decided to change the approach to a simpler and cheaper facility.

The new CLIPPER consists in a unique isothermal loop operating at 500 ºC. The main advantages are the lower PbLi inventory and the suppression of a very complex and expensive heat exchanger. In CLIPPER, the PbLi is heated, melted and cleaned outside the loop, in a tank integrated in a dedicated glove box under argon atmosphere. The test section includes a prototype of permeator (TRITON) and its auxiliary systems, such as its associated vacuum system and instrumentation. TRITON consists of a rectangular multi-channel component with vanadium membranes. A novel gas injection system specifically designed for CLIPPER is used to introduce the gases that must be extracted through the permeator (hydrogen isotopes). This system, based on a multi-tube component with permeable niobium membranes, is able to solubilize the hydrogen in the PbLi up to the required concentration.

The final design of CLIPPER is presented together with the integration of its main components, including a thermomechanical assessment of the loop.