Following the Three Mile Island (TMI) Unit 2 accident, it was determined that due to the unusual radiological conditions created, an improved thermoluminescent dosimetry (TLD) system was needed to support the cleanup and recovery. As a result, a Panasonic-based TLD system was developed and installed by GPU Nuclear at the TMI facility. The resulting modified 802-type Panasonic dosimeter design and associated algorithm were developed under contract by Phillip Plato from the University of Michigan. This dosimeter/algorithm design provides for the use of a changing beta correction factor derived from beta spectral data collected by the dosimeter. The system computer-based processing equipment is driven using software developed under contract by International Science Associates. Long-term stability of the system is assured by an extensive quality control program integrated into the system operation. With the exception of several minor upgrades, the dosimetry system is essentially unchanged from its original implementation in February 1983. Additionally, the system has maintained continuous National Voluntary Laboratory Accreditation Program certification of all monitoring categories.