The role of radiation instruments in the recovery of TMI-2 [Three Mile Island Unit 2]

Recovery, defueling, and restoration of Three Mile Island Unit 2 (TMI-2) to an environmentally stable configuration has been a labor-intensive effort that had to be conducted in complex radiological conditions of varying field intensities. Part of the success of the TMI-2 radiological controls program in minimizing worker exposure can be attributed to the effective use of a variety of portable instruments. A key component to the TMI-2 radiological controls program was the extensive characterization of source terms. Systematic surveys had to be conducted to quantify general radiation fields, locate hot spots, and establish surface contamination levels and airborne concentrations of radionuclides. Detailed and accurate radiological surveys and field measurements are essential to as low as reasonably achievable reviews, radiation work permit specifications for protective measures, and job briefings. Radiological instruments used at TMI include a variety of devices capable of assessing radiation fields from sealed sources, contaminated surfaces, and airborne radioactivity. At TMI, the maintenance and calibration of radiological instruments is conducted on site by a group of qualified technicians who are an integral part of the Radiological Controls Division. All calibration and repair is proceduralized and subject to a variety of audits, inspections, and internal and external assessments