Operation of a Fluorinert cooling system for the TFTR TF coils and TFTR Coil Flowswitch Monitoring System modification to accommodate the TF Alternate Cooling System (Fluorinert)

Abstract

The Tokamak Fusion Test Reactor (TFTR) at the Princeton Plasma Physics Laboratory (PPPL) employs Toroidal Field (TF) and Poloidal Field (PF) coils to generate the magnetic fields required for fusion plasma confinement. Several small deionized cooling water leaks in several TF coils had occurred and impacted TFTR operations. In order to prepare the TF coils for D-T experimental runs, the TF coil's deionized water coolant was replaced with a dielectric fluid-perfluoroheptane (3M Fluorinert PF-5070) in May 1993. The TF Alternate Cooling System (Fluorinert) is now in the operational phase. This paper describes how the TF Alternate Cooling System (Fluorinert) is operationally different from its predecessor (water) and how the Water Systems Group participated in the testing of the system. Operations and the special techniques that the TF Alternate Cooling System requires for maintenance are a part of this paper. The training of the Water Systems personnel in order to effectively monitor the controls and equipment for Fluorinert cooling during tritium operations is also addressed. This paper also describes the application of commercially available hardware and software to mitigate the consequences of a coil cooling flow loss. The TFTR Coil Flowswitch Monitoring System is devoted to coil protection and employs a programmable logic controller (PLC) to monitor the cooling flow at the outlet of each coil's cooling path. The system inhibits field coil rectifier operation when failure conditions exist and employs various redundant and stuck mode features. The Coil Flowswitch Monitoring System was initially installed in February, 1988 and modified in May, 1993 to accommodate the addition of a pump and a split of cooling paths. This paper will also discuss the PLC's reliability and operational history.