The Fermi National Accelerator Lab's (Fermilab's) long, and very necessary, shutdown is over. An amazing amount of work was done. Repairs, upgrades, installations, and alignments were among the main types of work completed. Although the bulk of the work was done in the Accelerator Division (formerly known as the Beams Division), personnel from the entire laboratory's divisions and sections and some from outside the lab, were involved. For example, Fermilab's survey alignment group received much-needed assistance from the Stanford Linear Accelerator Center (SLAC) survey department. All the work was coordinated by the AD Operations Department.
Subsequent to the shutdown, the Fermilab Recycler Ring, a permanent magnet antiproton storage ring, after many vacuum leaks and alignment problems were fixed, has achieved its design parameters. A new electron beam for a pelletron will be used eventually to cool the stored antiprotons. The connection between the building that houses the pelletron to the main injector tunnel, where the Recycler Ring is located, was completed during the shutdown.
All this work was conducted under the watchful eyes of the Accelerator Division's safety department. All jobs were initially reviewed and scheduled to minimize dose to personnel. We reported on the preparation for the booster jobs in the previous issue of this newsletter. As low as reasonably achievable (ALARA) principles were extensively observed. All hot jobs went through ALARA preplanning, which included total-dose-for-the-job estimation, radcon technician supervision, and postjob ALARA reviews. In addition to the standard dosimeters, pocket dosimeters were worn by the workers, and all daily doses were tracked in a database.
The total shutdown dose equivalent, as measured by pocket dosimeters, is about 9 person-rem. In a week-by-week plot, a mild peak was correlated with the time of the most significant radiological work in the booster. A considerable amount of this dose was incurred in making improvements that should greatly reduce future exposures in the booster. In general, individual exposures were kept to reasonable levels and the ability to predict exposures was generally accurate, with a slight bias toward small overestimates, likely preferred to underestimates.