Recent progress on fusion nuclear technology in inertial fusion

Abstract

Abstract Inertial fusion energy (IFE) ignition and gain facilities based on lasers, the national ignition facility (NIF/USA) and the laser megajoule (LMJ/France), will be operating in the first years (2002–2010) of the next century. The conceptual design of another ignition and gain facility, the heavy ion design of ignition facility (HIDIF), is under way in an European initiative. NIF's target emission spectra show the differences in the energy fraction of debris and X-rays between direct and indirect driven (hohlraum) targets and the importance of the angular dependence in hohlraum emissions. Emerging neutrons could limit the availability to the chamber area because of activation and produce damage in the final optics; however, the NIF/LMJ designs do not envision significant effects in routine or accident conditions. Damage from debris and X-rays to the chamber wall has been extensively analyzed, concluding on the use/choice of coating materials (B4C, B, C). Removal depths in the wall/chamber have been estimated, together with the materials deposition in areas such as final optical assembly (FOA), target positioner, and debris shields. Differences in NIF and LMJ chambers include essentially the concrete shielding sandwiches in the Al layers in the case of LMJ. The use of present technology of composite materials, instead of Al, will give a better contact dose rate in some frequent access areas of the facilities. After previous reactor concepts reported in the early 90's, additional work has been done on LIBRA-SP, HYLIFE-II and KOYO designs, establishing new approaches to protection and material consideration, together with systems such as the target injector (HYLIFE-II). The choice and disposition of materials in KOYO (SiC + HT-9), LIBRA-SP (HT-9) and HYLIFE-II (SS304) is presented for handling and disposal considerations, with clear consequences in the classification of areas for shallow land burial (SLB). The importance of uncertainties in nuclear data will be discussed, and its influence in early conclusions. The effect of neutron spectrum in accidental release emissions by activation of materials is also critical in the characterization of the components of the reactor, and will be discussed.