Abingdon, United Kingdom
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Day C.,Karlsruhe Institute of Technology | Butler B.,Culham Center for Fusion Energy | Giegerich T.,Karlsruhe Institute of Technology | Lang P.T.,Max Planck Institute for Plasma Physics (Garching) | And 2 more authors.
Fusion Engineering and Design | Year: 2016

In the framework of the EUROfusion Programme, EU is preparing the conceptual design of the inner fuel cycle of a pulsed tokamak DEMO. This paper illustrates a quantified process to shape a R&D programme that exploits as much as possible previous R&D. In an initial step, the high-level requirements are collected and a novel DEMO inner fuel cycle architecture with its three sub-systems vacuum pumping, matter injection (fuelling and injection of plasma enhancement gases) and tritium systems (tritium plant and breeder coolant purification) is delineated, driven by the DEMO key challenge to reduce tritium inventory. Then, a technology survey is carried out to review potential existing solutions for the required process functions and to assess their maturity and risks. Finally, a decision-making scheme is applied to select the most promising candidates. ITER technology is exploited where possible. As a primary result, a fuel cycle architecture is suggested with an advanced tritium plant that avoids full isotope separation in the main loop and with a Direct Internal Recycling path in the vacuum systems to shorten cycle times. For core fuelling, classical inboard pellet injection technology is selected, in principle similar to that proposed for ITER but aiming for higher launch speeds to achieve deep fuelling of the DEMO plasma. Based on these findings, a tailored R&D programme is shaped that tackles the key questions until 2020. © 2016 Chr. Day.

Donne A.J.H.,Programme Management Unit | Cowley S.,Culham Center for Fusion Energy | Jones T.,Culham Center for Fusion Energy | Litaudon X.,Programme Management Unit
Journal of Fusion Energy | Year: 2016

Prolonged operation of the Joint European Torus (JET) in a set-up involving all ITER partners will be beneficial for ITER. Experiments at JET with its ITER-like wall and using a D–T plasma mixture will help to mitigate risks in the ITER research plan. Training of the ITER operators, technicians and engineers at JET will safe valuable time when ITER comes into operation. Moreover, the way in which the future ITER experiments will be organized can already be experienced at JET, by imposing a similar organisational structure. This paper will present arguments in favour of an extension of JET and additionally briefly discuss a number of enhancements that will make experiments on JET even more relevant for ITER. © 2015, The Author(s).

Vincenzi P.,Consorzio RFX | Vincenzi P.,University of Padua | Koechl F.,EURATOM | Garzotti L.,Culham Center for Fusion Energy | And 8 more authors.
Nuclear Fusion | Year: 2015

Plasma fuelling and density control are an open issue regarding EU DEMO studies and solutions may be different from present day experiments. The present paper addresses through JINTRAC core transport code simulations the feasibility of different fuelling methods such as gas puff and pellet injection and the influence of neoclassical and anomalous inward pinch in the edge transport barrier in order to achieve and control the target DEMO density. Given the expected high fusion power production, He accumulation in the plasma core is a critical issue, and an estimation of the influence of impurities (He, Ar, and W) on core fuelling and plasma dilution is given together with a discussion on D-T core balance. The DEMO reference scenario investigated in this work is characterized by a peaked density profile, which requires a careful core fuelling. Due to the large pedestal temperature gradient, gas puff may not be a feasible option for core density control, unless assuming a large anomalous inward pinch in the edge transport barrier of more than ∼2 m s-1. Pellet injection from the high field side of the torus, on the contrary, may represent a viable solution for core fuelling and D-T ratio control. The effect of pellet mass, speed, and injection geometry is also discussed in the present paper. Regardless, core fuelling efficiency with pellet injection is almost entirely determined by the presence of E × B drift. © 2015 EURATOM.

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