Development of membrane cryostats for large liquid argon neutrino detectors

A new collaboration is being formed to develop a multi-kiloton Long-Baseline neutrino experiment that will be located at the Surf Underground Research Facility (SURF) in Lead, SD. In the present design, the detector will be located inside cryostatsfilled with 68,400 ton of ultrapure liquid argon (less than 100 parts per trillion of oxygen equivalentcontamination). To qualify the membrane technologyfor future very large-scale and underground implementations, a strong prototyping effort is ongoing: several smaller detectors of growing size with associated cryostatsand cryogenic systems will be designed and built at Fermilaband CERN. They will take physics data and test different detector elements, filtration systems, design options and installation procedures. In addition, a 35 ton prototype is already operational at Fermilaband will take data with single- phase detectorin early 2016. After the prototyping phase, the multi-kton detector will be constructed. After commissioning, it will detect and study neutrinos from a new beam from Fermilab. These cryostatswill be engineered, constructed, commissioned, and qualified by an international engineering team. This contribution presents the on-going effort on the development of the cryostatsand details the requirements and the current status of the design.