Tritium Technology and Safety at Jet

Abstract

D-T plasma operation has always been envisaged since the beginning of the JET Project and both the original design and subsequent modifications have been designed to take account of the requirements of D-T operation. A limited tritium experiment was carried out in November 1991 which generated 1.7 MW of fusion power. In addition to the physics objectives, this experiment was intended to provide results which would be important for the technology to be used in full D-T phase, such as tritium accounting and hold-up. Because of the limited usage of tritium it was possible to use a {open_quotes}once-through{close_quotes} system in which around 99% of the tritium was recovered. It is currently planned to have a daily throughput of around l0g of tritium per day in the full D-T phase, introduced through neutral beam and/or gas puffing. As it would be neither environmentally acceptable nor cost-effective to discharge even 1% of this to the atmosphere, a tritium recycling plant, known as the Active Gas Handling System (AGHS) has been constructed and is currently being commissioned. It was necessary to take several issues into consideration in the design of the AGHS to ensure that it and the JET machine would be capablemore » of being licensed for handling tritium. These were ensuring that {open_quotes}Best Practicable Means{close_quotes} were used to limit routine discharges to the environment; ensuring that routine radiation exposure of the JET workforce would be minimised; and ensuring that the risk to the workforce and the public arising from accidents would be acceptably low. The technology involved, waste management and regulatory issues are discussed further in the paper.« less