مطالعه تجزیه و تحلیل سیستم برای راکتور DEMO همجوشی کره

A conceptual design study for a steady-state Korean fusion DEMO reactor (K-DEMO) has been initiated. Two peculiar features need to be noted. First, the major radius is designed to be just below 6.5 m, considering practical engineering feasibilities. But still, high magnetic field at the plasma center around 8 T is expected to be achieved by using current state-of-the-art high performance Nb3Sn strand technology. Second, a two-stage development plan is being considered. In the first stage, K-DEMO will demonstrate a net electricity generation but will also act as a component test facility. Then, after a major upgrade, K-DEMO is expected to show a net electric generation on the order of 300 MWe and the competitiveness in cost of electricity (COE). Feasibility of such a practical, near-future demonstration reactor is studied in this paper, based on a zero dimensional system analysis code study. It was shown that a net electric generation on the order of 300 MWe can be achieved below the optimistic βN limit of 5. The elongation of K-DEMO is around 1.8 with single null configuration. Detailed optimization process and the resultant various plasma parameters are described.

Conceptual design studies for fusion demonstration reactor (DEMO) could be classified into two categories. In one extreme end, the high toroidal magnetic field approach is targeted to achieve maximum fusion power, whereas in the other end, the high βN approach is aiming at an easier steady-state operation. If we consider another end, faster realization based on realistic near-future engineering constraints, then it may be argued, for example, that the overall size should be relevant to those of the ITER, in order to directly incorporate the progress in tokamak plasma physics during the ITER operation phase [1] and [2]. A pre-conceptual design study for K-DEMO has been initiated. A National Fusion Development Roadmap had been released in 2005 and Fusion Energy Development Promotion Law was enacted in 2007 to promote a long-term cooperative fusion research. The main design philosophy at the moment can be summarized as faster realization based on realistic near-future engineering constraints. With such a spirit, the major radius is designed to be less than 6.5 m. Plausible radial builds are being studied, including toroidal field (TF) magnets. Based on the physical size of the TF magnets, two options for the radial builds are discussed in our recent work [3]. Another critical feature of the current K-DEMO pre-conceptual design study is a unique two-stage development plan. In its first stage, K-DEMO will be operated partially as a component test facility. Based on the component test results, a major upgrade will be carried out in the second stage development, by replacing relevant in-vessel components in order to achieve a net electricity generation on the order of 300 MWe and the competitiveness in cost of electricity (COE). In this work, the feasibility of such a practical, near-future demonstration reactor will be discussed, mainly to focus on the plausible plasma parameters in order to achieve a net electricity generation on the order of 300 MWe, for two design options, using a 0-dimensional system analysis code [4].

In summary, a system analysis study on the current two options for the K-DEMO has been carried out. The main design philosophy at the moment can be stated as faster realization based on realistic near-future engineering constraints. With such a spirit, the feasibility of such a practical, near-future demonstration reactor was mainly focused. In order to demonstrate the competitiveness in COE, at least, the net electricity of 300 MWe can be generated. System analysis has been carried out for the operation at a reasonably practical value for βN of 4.2 and maximum toroidal field, BT of 16 T (7.72 T at the plasma core), a sort of a compromise between high βN and high BT approach. First, the plasma and bootstrap currents were roughly scanned and then detailed q profile variations are considered. Only a weak negative shear with a bit high q0 of 2.5 seems to be good enough for the required net electric generation on the order of 300 MWe.