High Power 14 MeV Neutron Sources for Tests of Materials

An assessment of the available alternatives for fusion relevant neutron sources

“…The first proposals of construction of a tokamak purely for fusion material testing appeared in 1993 in 'IEA Workshop of Fusion Neutron Sources' held in Moscow, which followed the conclusions of 'IEA Workshop on Selection of Intense Neutron Sources' held in Karlsruhe in 1992, where a Li(d,n) neutron source was acclaimed [89]. During this workshop, it was agreed that regarding the capital cost involved on a neutron source, not more than 10% of ITER's could be acceptable [131]. The concept of a fusion reactor following tokamak's concept is, unfortunately, in the near-term future non-realistic to consider (disregarding the unsolved material problems to be faced by the severely irradiated plasma facing equipment of such a facility) due to the 10 billion range construction cost, hundreds millions electricity yearly cost of operation of the 100 MW range facility needed or the hundreds millions yearly cost of the 10 kg range tritium needed to operate [131,132].…”

“…During this workshop, it was agreed that regarding the capital cost involved on a neutron source, not more than 10% of ITER's could be acceptable [131]. The concept of a fusion reactor following tokamak's concept is, unfortunately, in the near-term future non-realistic to consider (disregarding the unsolved material problems to be faced by the severely irradiated plasma facing equipment of such a facility) due to the 10 billion range construction cost, hundreds millions electricity yearly cost of operation of the 100 MW range facility needed or the hundreds millions yearly cost of the 10 kg range tritium needed to operate [131,132]. Ambitious proposals like a Component Tests Facility (CTF) [133] and the like [134,135] will certainly become a reality this century, but they are mistiming and unfortunately nowadays basically remain as proposals on paper: risks would be too high as today we do not know how to control in a stable manner fusion reactions beyond the short periods obtained in the 90s in JET [69] and TFTR [70,71]; only ITER in the middle 2030s will show.…”

“…The length of the facility would be substantially shortened to few tens of m. Practically all the power would then be consumed in neutral beam injectors; it has been estimated that an injection power of 60 MW and injection energy of 65 keV are sufficient to ensure the desired neutron flux density in the testing zone (~2 MW m −2 ) at an electron temperature of 0.65 keV. An asset of this concept is the relatively small neutron flux incident on the first wall, excluding the rather narrow zones intended for testing materials (making unnecessary a frequent replacement of equipment in contact with the plasma in other regions) [131] and the low tritium consumption of around 100 g/fpy [140].…”

Modulating the neutron flux from a mirror neutron source

“…Detailed description of various aspects of the source operation can be found in Refs. [1], [7] and [8]. When using these references, one has to remember that, during the twenty-five years since this concept of the source had been proposed, a large number of versions of the source had been assessed, with a broad range of possible operation parameters.…”

“…This is a property that allows a concentration of the neutron production in a well-defined region of the source, see, e.g., Refs. [1,2,3,7]. It proves to be beneficial for controlled periodical axial displacement of a right boundary of a high-flux zone, so that the neutron production at the right end of the "shelf" decreases to a small value and then comes back (we are referring here to the right-hand test zone shown in Fig.…”