29th Symposium on Fusion Technology (SOFT 2016)

P4.169 Tritium introduction module design for the JET tokamak

8 Sep 2016, 14:20

1h 40m

Foyer 2A (2nd floor), 3A (3rd floor) (Prague Congress Centre)

Board: 169

Poster H. Fuel Cycle and Breeding Blankets P4 Poster session

Speaker

David Wilson (CCFE)

Description

In support of ITER, two experimental campaigns are foreseen to take place at JET, the first with tritium only and a second with deuterium plus tritium to explore the machine fusion potential. To support the tritium operation, a total of five Tritium Introduction Modules (TIMs) are expected to be installed at JET, one on top of the machine, another in the mid-plane and three in the divertor region. Since no human intervention or serviceability to the TIMs is foreseen during the tritium experimental campaigns, their design needs to incorporate redundancy, reliability, secure operation and conform to JET specific design, inspection, testing and safety case requirements. The challenges to the design in complying with operational requirements, connection to the Active Gas Handling System (AGHS), predicted neutron and gamma levels, were taken into account and shaped the design choices presented here. The function of a TIM is a controlled tritium injection to the vacuum vessel while preventing accidental release to vessel or environment. TIMs consist of a secondary containment vessel, internally filled with a purge gas of recirculating Nitrogen, up to 3 bar. This vessel also encloses the primary tritium containing components, including the piezoelectric valves, the primary tritium reservoirs (each holding 1g at 800 mbar abs), pressure and temperature instrumentation for accurate tritium inventory accounting. Prototype piezo-valves developed by VAT Vacuumvalves AG with a stroke of 160μm and orifice area of 5.2mm²2, are tested for a flow rate of 1.6 Bar.L/s. The TIMs are connected through a supply network involving distribution vessels and transfer lines connecting to the AGHS valve box and ultimately to the primary Uranium bed storage and to the monitored discharge stack for the nitrogen exhaust. This paper describes the module design and details the operational and safety case requirements considered for safe Tritium operation.