TFTR tritium accounting system for DT-operation

TFTR has been using tritium as a fuel gas as part of its Deuterium-Tritium (DT) experimental operations with over 600 kCi processed through the site and over 400 kCi injected. Careful inventory and accounting measures are required to ensure site and regulatory safety tritium limits are not exceeded. Tritium management is accomplished through a database system to coordinate experimental needs within these limits. A TFTR Nuclear Materials Custodian (NMC) oversees Tritium Transfer Operations (TTO) using accounts based on specific system physical locations including tritium product containers, uranium beds (hydration), Gas Holding Tanks (GHT), disposable Molecular Sieve Beds (DMSB), the Tritium Gas Injection System (TGIS), and the Tritium Purification System (TPS). Methods used to coordinate and track TTO's include: single source TTO serial numbers issued by the TFTR Shift Supervisor (TFTRSS) as TTO authorization, TTO verification receipts, and daily NMC database updates with reports issued to appropriate groups. Tokamak tritium operations are controlled and monitored through a computer system that automatically measures and generates tritium injection value reports, as well as providing interlocks between the TGIS and the personnel safety tritium monitors. This system also provides historical trends of tritium values in the entire TGIS, consisting of 14 injector volumes and an interconnecting manifold, to identify inter-system tritium leakage. NMC tritium accounting control involves aspects such as: tritium measurement data flow, verification, instrument calibration, measurement controls, TTO control limits, Material-in-Process (MIP) evaluation, database error detection and correction, and account material balances. Details of these areas are discussed with emphasis on the tight controls required for the very low tritium inventory level permitted for TFTR, and lessons learned from the past 23 months of tritium operations.