Systems design description of the Thermal Transient Test Facility (TTTF)

Abstract

The Thermal Transient Test Facility (TTTF) is a hightemperature, high-pressure sodium test facility designed to subject test specimens to internal pressure and intermittent thermal downshocks to produce thermal ratchetting. The facility was built as a part of the ORNL High-Temperature Structural Design Methods for Liquid-Metal Fast Breeder Reactor (LMFBR) Components (189a No. 10556) program. The purpose of the program is to develop a verified design technology, including methods and criteria, applicable to the high-temperature, long-term operating conditions expected for LMFBR vessels, components, and core structures. In the TTTF, a test specimen is filled with static sodium at pressures to 700 psig and at temperatures to 1100°F and subjected to a thermal downshock at temperature rates to 30°F/sec by forcing colder temperature-graded sodium through the test section while maintaining the test section at pressure. The high-pressure portion of the system contains approximately 250 gal of sodium; when the system is drained, the low-pressure sump tank contains approximately 750 gal of sodium. Strain rates are measured on the test section by hightemperature capacitance-type strain gages. A fast-scan dataacquisition system is used to record pertinent test measurements on magnetic tape for computer processing. The facility is equipped with automatic control and alairm equipment to permit unattended operation. This report presents the design description of the various systems that make up the TTTF: the sodium system, the highand low-pressure argon systems, the sodium purification svstem, the test section, the electrical system, and the instrumentation and control systems.