Abstract
Fermi National Accelerator Laboratory (FNAL) is developing the international Long-Baseline Neutrino Facility (LBNF) and Deep Underground Neutrino Experiment (DUNE) to advance neutrino science. The flagship of the DUNE project consists of a large particle detector constructed one-mile (1.6 km) beneath the surface at the Sanford Underground Research Facility (SURF) in Lead, SD. The SURF detector is the largest of its type ever built and is comprised of four cryostats totaling 70,000 tons of liquid argon (LAr) to record neutrino interactions with unprecedented precision. Each cryostat houses a detector, the first includes 150 Anode Panel Assemblies (APA) submersed within 17,500 tons of LAr. Before installing 150 APA within the SURF detector they will be cryogenically cooled to nominally 90 K at the APA Test Facility (APATF) utilizing nitrogen flows. The APATF cryogenic system is entirely located one-mile underground at the SURF facility and includes nominally 13 kW of refrigeration at 80 K, cryogenic transfer lines, APA test cryostats, a cryogenic control system, and various control and pressure safety elements to ensure performance and safety requirements are achieved. The APATF preliminary design is in progress and major considerations include an efficient, cost-effective mechanism to deliver the required refrigeration to the APATF underground, support of rigid testing intervals to support the DUNE operating schedule, temperature stability of the APA and electronics within cryostats, efficient cryogenic system operation to minimize heat leak and/or liquid nitrogen consumption, thermo-mechanical stability and flexibility of components, and pressure safety of the APATF cryogenic system. Installation and integration of the APATF cryogenic system within the footprint and to adjacent sub-systems is also discussed.
Highlights
The Deep Underground Neutrino Experiment (DUNE) Anode Panel Assembly Test Facility (APATF) cryogenic system is in preliminary design for development of facilities and infrastructure capable of testing a total of 150 Anode Panel Assemblies (APA) in pairs of two for 75 total tests of dual APAs
It is estimated that each APA coldbox test has a 4 day (96 hour) thermal cycle and the turnaround time between tests is such that all 75 pairs are tested within approximately a 1-year time span, with cryogenic APATF operations beginning in early 2026 [1]
The scope of this paper is principally focused on the design and development of the underground cryogenic system for supporting low temperature operation of the APATF coldboxes
Summary
The Deep Underground Neutrino Experiment (DUNE) Anode Panel Assembly Test Facility (APATF) cryogenic system is in preliminary design for development of facilities and infrastructure capable of testing a total of 150 APAs in pairs of two for 75 total tests of dual APAs. Refrigeration and transport of LN2 Provisions are in preliminary discussions and estimation for a mechanical nitrogen liquefier to provide up to 13 kW of refrigeration at 80 K to the APATF cryogenic system to support the peak required cryogenic load for three coldboxes of up to 2975 kg LN2 per test or at peak operation with three coldboxes running approximately 4150 L/day, including design margin of 50%. As contingency for this mechanical liquefier, preparations are being investigated to allow the transport of LN2 via portable dewar(s) on the elevator cage. A plot of the estimated mass flow of saturated LN2 to the coldbox during cooldown is presented in figure 3
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