2nd IAEA Technical Meeting on

First Generation of Fusion Power Plants: Design & Technology

20 - 22 June 2007, Vienna, Austria

Meeting Summary

Power plant concepts where presented on a regional approach, having different final aims leading to different technical solutions. In the EU, the three-step approach (ITER, IFMIF, DEMO) being sequential, based on budgetary considerations, may not be the fastest track. The fusion track could be accelerated at the cost of increasing the risk and following more conservative aims. In Korea, power plant studies are on going and results where presented from a code that finds the design parameters which satisfies the plasma physics and engineering constraints or optimizes the design depending on the given figure of merits. The development objectives for the Chinese power plant concept are to continue the domestic plasma research effort using the experiments such as HL-2A (HL-2M) and EAST, to strengthen the domestic fusion reactor research and to cooperate with international effort in DEMO design activities. A multiple-function fusion reactor as been proposed based on the existing fusion technology for exploiting the possibility of earlier application of fusion energy as volumetric neutron source. The Chinese reactor aims at different types of utilization such as fission waste disposal, plutonium 239 breeding from uranium 238, hydrogen producing, tritium producing, components test for fusion reactors and electricity power plant demonstration. The Indian power plant concept has been developed based on a code that includes physics and engineering constraints and has been validated by applying it to existing tokamak devices. The design was chosen to be conservative for a power plant delivering 3.3 GW (Q=30). A concept of a power plant based on compact stellarator configuration with dimensions comparable to tokamak configuration was presented as a possible US option. Reduction on CoE by 30% and significant reduction of radwaste have been achieved in the present design when compared to previous ones. Detailed results for several concepts were presented for the divertor heat load indicating that with 3GW fusion power and 200MW heating power, the radiated power fraction should be above 60%. The studies showed how coolant choice implies in the radial build depending if to use liquid or gas coolant. As for the conversion processes several cycles, alternative to the Rankine, were discussed such as the indirect Brayton and the supercritical Rankine cycles offering improvements on the overall conversion efficiency. One presentation addressed the concept for inertial fusion energy power plant. In this new concept the pre-compressed fuel core (1000x solid density) is directly heated to 5 keV with a pico-second laser pulse from a heating laser. This fast ignition scheme enables to design a power plant with a 1MJ-class, compact laser whose output energy is 1/4 of the previous central ignition scheme.

The environmental and safety impact of fusion was addressed in three presentations. As for radwaste management strategy, avoiding geological disposal, recycling and clearance seems to be a more attractive path. However much work remains to be done in homogenizing the clearance standards, define specific fusion guide-lines, availability of a market for cleared materials and the acceptability of the nuclear industry to recyclable materials. In Korea efforts are on-going in establishing the contents, schedule plan, and strategies in developing regulatory technologies aiming at establishing future licensing frame work for fusion power plant in Korea. Failure mode analysis was developed in detail for the Chinese ITER test blanket module based in a bottom-up approach. All the possible failure modes that could occur in the operating states were evaluated in terms of: accident frequencies and relative category classification, failure cause and possible action to prevent the failure, consequences, and actions to prevent or mitigate the impact of the resulting consequence.

Detailed works on several blanket concepts have been presented. The US is developing a study for a new plasma facing component based on boron infiltrated in a W-mesh. This BW-mesh concept is at a very early stage of development and will be tested in DIII-D. Concepts for integration of the Helium Cooled Pebble Bed blanket into the reactor using the ‘Multi-Module-Segment’ (MMS) were discussed in detail. One of the main advantages is that this connection does not have to be handled from inside the vessel and compensation for EM loads is intrinsic by design. A study for energy storage for re-initiating a pulsed fusion power plant with 4-8 h operation and dwell time of 5-20 min was presented. Metal hydrides could be the best candidates for such a system for several reasons, like very large heat of fusion and, moreover, an option for combining heat from fusion with heat from chemical reaction, thereby increasing the latent heat based thermal storage capacity.

Co-generation of hydrogen was discussed by three authors. As the hydrogen marked is potentially 3x higher than for electricity this co-generation approach would make fusion much more attractive. Blanked designs to cope with the high temperatures (~1000C) at optimal efficiency for hydrogen and electricity production were presented.

Two works discussed the role of fusion in the future and the share of fusion in the energy market. The present projections for impact on climate changes indicate that it is absolutely necessary to keep CO2 concentration below 550 ppm to avoid an average earth temperature increase of 3C. Giving the present trends, it seems justifiable and urgent to strengthen the fusion programme developing technology even if in a non-ideal form but faster, by relaxing the targets for the internal cost of electricity from the first generation of fusion power plants. Correspondingly, reduced targets for the technical performance (e.g. plasma scenarios, materials endurance, blanket efficiency) of DEMO(s) aiming at demonstration of fusion electricity production in twenty years, may lead to widespread deployment of fusion power earlier than in previous fast track scenarios. Present projections for China economic growth, population increase and the demand in energy reaching 1.5 TW in 2050 would require a serious strategy on development of energy. The most promising path in satisfying this demand with reduced environment impact would be to increase the fissile power contribution (now only 1%) to 6% of the total capacity, duplicate the renewable contribution to achieve 30% of operating power plants and promote high efficiency coal power plants. However due to limitations to natural uranium ore and increase of radwaste that this development would imply an aggressive fusion road map is being considered in China to accelerate fusion development. The targets are to achieve steady state operation on EAST in 10 years, contribute to the design, construction and assembly of ITER, and initiate construction of the first multi-function fusion reactor by 2020-2030.