A scientific quest to search for dark matter has led to the opportunity for ASSDA Member and Accredited Fabricator Tasweld Engineering to fabricate a specialised stainless steel tank, known as SABRE (Sodium Iodide with Active Background Rejection) Veto Vessel to help facilitate Australian research into answering one of the universe's unsolved mysteries.
The University of Melbourne received $5 million in federal funding to build the Stawell Underground Physics Laboratory (SUPL) in an 
unused gold mine in Western
Victoria. The facility will house the SABRE Veto Vessel, shielding it from astrophysical particles and enabling a range of experiments to be undertaken to determine the existence of dark matter, a form of matter that does not directly interact with light. Dark matter is by its nature, extremely hard to detect. The SUPL location is approximately 1km underground to use the earth's shield to screen out astrophysical particles, background noise and environmental factors that interfere with signals from dark matter.
The SABRE Veto Vessel was designed by the University of Melbourne in conjunction with FE Consulting Design Engineers and Tasweld Engineering. To deliver the best probability for experimental success, grade 304 stainless steel was used for the vessel's manufacture. In addition to the material's durability, gleanability and corrosion resistance, stainless steel was specified most importantly for a specific property; low radioactive content. The presence of certain radionuclides negatively affects the detection experiments, and therefore sourcing material with low radio emissivity was critical. The stainless steel plate was imported from a supplier in Germany with experience in this application and involved stringent validation testing.
The vessel took 600 man-hours and was manufactured at Tasweld Engineering's Warrnambool workshop to AS 1210 standards with rigorous equipment and welding processes applied to prevent material contamination. All welding was carried out using a TIG process, with lanthanated tungsten electrodes, and all consumables were new to avoid cross contamination. The 2.6m tall, 1800kg vessel features access ports for electrical and other connections.
The SABRE Veto Vessel was completed in October 2019 and has been temporarily installed in a laboratory at Swinburne University of Technology's Wantirna Campus for preliminary testing while the SUPL is being constructed. For the next stage of the project, Tasweld Engineering have been contracted to manufacture an additional flange assembly to allow the use of different attachments during various experiments.
Tasweld Engineering's expertise and superior workmanship, and the use of stainless steel, has delivered a positive contribution to science in a quest to unlock the mystery of dark matter and to a research facility that aims to conduct better quality experiments, including the effects of radiation in cancer cells.
This article is featured in Australian Stainless Magazine issue 68, 2020.
