The Sanford Lab will have its own set of gamma counters on the surface at the warehouse for neutron activation and we envision distributing these to the deeper site as it becomes available. An intermediate level is required for segregating ultra-sensitive detectors in the main 4850 FAARM from radioactive samples that have gone through neutron activation, NAA. This intermediate level should include a radiochemistry lab. This level should have a modest overburden (≥ 300 mwe) but can be deeper as well. Easy access, even drive-in access, would be preferred. This level could also be used for storage of solid materials underground, such as copper, etc. Long-term storage of materials dictates a preferred ≥ 800 mwe for safety. At this slightly deeper level, the same lab could also be used as a crystal growth and detector fab installation.
Access to dedicated screeners at the same level would make a crystal/detector fab installation more efficient, and in general, it would be a good idea to keep all these modalities under the supervision of a dedicated set of technicians. However, one can also envision a separation into a surface facility for the radiochemistry and dedicated NAA screeners and a deeper location for the pre-screeners, storage of materials, and crystal growth. A surface facility can be populated immediately and the intermediate level could be populated soon thereafter. Building of the water shield and offices at the 4850 level will begin as soon as possible, but population of the site will require completion of the water shield and introduction of clean procedures, proper airflow, availability of purified water, and radon mitigation – either lab-wide ventilation improvements or the our own system of nitrogen purges or vacuum swing technology for radon cleansing.
Once these are completed, screeners can be installed at 4850, while the ultra-sensitive tank is built. If the immersion tank is actually incorporated into the water shield wall, then the shield aspects must also be completed first, but commissioning of the immersion tank active element will be the last item to be completed.