A layout of the tritium plant subsystems for the european demonstration fusion power plant

The European demonstration fusion power plant (EU-DEMO) project intends to prove the commercial viability of nuclear fusion as a source of safe and clean energy. This fusion power plant will be fueled by a 1:1 deuterium-tritium (hydrogen isotopes) mixture that will need to be recycled for environmental and economic reasons due to the low burn-up fraction. Tritium is a radioactive isotope that requires a special design of any handling facilities to be “tritium compatible” and a series of layers of protection to prevent any release of tritium to the environment above the permitted values. Moreover, tritium is scarcely available which makes it again crucial to design the tritium systems, the so called fuel cycle, such that the inventory is minimized. The EU-DEMO fuel cycle will be housed inside two buildings, the tokamak building and the tritium plant building. The first one will contain the reactor, its fueling systems and the direct internal recycling loop. The tritium plant building, which is the subject of this work, will accommodate an inner tritium plant loop and an outer tritium plant loop. In this thesis, a methodology for estimating the required footprint of the tritium plant and optimizing its layout is proposed. This is accomplished by identifying all the necessary equipment of the plant, estimating their physical dimensions, and allocating them into primary and secondary confinements (e.g. gloveboxes and rooms), for which their footprint and volume is obtained. By arranging these rooms inside a multistory building, the final layout is achieved. This methodology takes into consideration the fuel cycle processes and at the same time defines personnel and process safety, construction, operation and maintenance criteria to obtain an optimized layout suitable for the entire life cycle of the facility, while keeping in mind the need for minimizing the tritium inventory. Afterwards, this work puts forward a piping dimensioning strategy, defining design basis and calculation sequences supported on European Norms as well as optimization criteria to achieve a reasonably low tritium inventory in piping required to connect confinements and rooms. The presented tritium inventory determination focuses on the piping under normal operation of the plant, while the inventory inside the units is out of the scope of this work, even though it is taken into account for the development of the layout. The application of the developed methodologies resulted in the identification of 627 process equipment which have been grouped into 29 gloveboxes, 2 coldboxes and 19 metalboxes. These confinement structures can be housed inside a compact seven-story-building design, with a projected footprint of 2200 m2, a cumulative footprint of 11240 m2, an external volume of 57030 m3 and external dimensions of 35.8 m of height, 74.0 m of length and 30.9 m of width. Lastly, the resulting tritium inventory inside interconnecting pipes under normal operation is found to be in the order of 0.2 g with only 10 pipe types (outer diameter and thickness combinations).