Source Well Room
Four calibration source wells are located in the calibration facility. The wells were designed with personnel safety, ease of use, and high throughput in mind. Each well is 0.3 m (1 ft) in diameter by 10 m (33 ft) deep and contains a trolley-mounted, double-encapsulated radionuclide source. Trolley movement is controlled by a dedicated personal computer programmed to position the source to provide the desired exposure or dose equivalent rate at the top of the well (see Figure 2.8). Source-to-detector distances are automatically corrected to compensate for temperature, pressure, and source decay.
Wells 1, 2, and 4 contain 0.30 Ci, 15.3 Ci, and 6.1 Ci of 137Cs (as of 3/2005), respectively, and provide 662-keV photon fields from 50 µR/h to approximately 20 R/hr.
Well 3 contains a 57 mCi (as of 3/2005) of 252Cf, which provides neutron dose equivalent rates from 1 mrem/hr up to 600 mrem/hr for select neutron monitors. This well is calibrated specifically for each type of detector used to enable the accurate reflection of free-field conditions. Currently, it is configured for NRC AN/PDR-7O "Snoopy" and Eberline NRD-based detector calibrations referenced to bare 252Cf.
Together, the calibration wells make it possible to perform instrument calibrations and evaluations over a wide range of exposure rates with great accuracy, convenience, and speed of calibration.
Point of Contact: James Rolph