The concept and parameters anticipated for the facility were briefly summarized in May 1977 in a document that served as the technical background document for the LCT annex of the IEA Implementing Agreement. In February 1978, ORNL issued a conceptual design report, providing more detail [1]. Evolution of the design continued after that time. Section 4.1 is the first comprehensive description of the facility to be published since the 1978 report. Section 4.2 describes the operation of the facility, from the first full-array cooldown in 1985 through the final warmup in 1987. It includes organization, chronology, performance of subsystems, and facility availability. A more detailed version of this section has been published as an ORNL report [2].