Fusion materials science at reactor 14-MeV neutron fluxes: upgrading RTNS targets into the multi-megawatt/m/sup 2/ regime

Abstract

The Rotating Target Neutron Source-II (RTNS-II) facility is the most intense continuous source of 14-MeV neutrons in the world. It is used to study the effects of fast neutrons on materials, to determine their suitability for use in fusion reactors. In RTNS-II, a water-cooled rotating target coated with titanium tritide is bombarded with deuterons. A small fraction of the incident deuterons fuse with the tritons in the target, producing 14.3-MeV neutrons. At present the neutron flux is substantially less than what a fusion test reactor would generate. This report examines the possibilities for upgrading RTNS targets to produce reactor-level neutron fluxes (or more). It is shown that the existing targets are operating near their thermal limit. However, modifications in target design and operating conditions are possible which could reasonably support up to a 30-fold increase in peak neutron flux (approx. 3 x 10/sup 14/ neutrons/cm/sup 2/-sec, or 6 MW/m/sup 2/). The irradiated volume could also be increased, if desired. It seems likely that with some research and experimentation with palladium underlayers, target cladding/overcoating, and/or in-situ retritiding, an acceptable target lifetime can still be achieved at this greatly upgraded neutron flux. The proposed target modifications consist of a number of significantmore » incremental improvements on the existing system, rather than one large breakthrough. Some of them could be implemented rapidly (time scale of less than a year); others would require somewhat more research (time scale of 2 or 3 years, depending on funding and staffing levels, and difficulties encountered). Each change can be independently omitted should technological difficulties arise. As such the overall RTNS upgrade process would be low-risk and high-payoff.« less