Fusion Materials Irradiation with a Spallation Source Eric Pitcher and Stuart Maloy Los Alamos National Laboratory

A materials qualification facility is one of nine gaps identified by the Greenwald Report Considering the long time that will be required to complete the detailed engineering design and to construct IFMIF, the question has arisen whether accelerator-based spallation neutron sources can provide insight on the microstructural evolution of materials at fusion-relevant He/dpa levels … a spallation neutron facility … could … eliminate the need for US participation as a full partner in IFMIF

Using a spallation source for fusion materials testing is not a new idea Kley, Perlado, et al. ( ) : EURAC proposal (600 MeV / 6 mA) Doran and Leiss (1989) : IEA Evaluation Panel Report concluded that d-Li, spallation, and beam-plasma concepts all have the potential to meet flux, fluence, and test volume requirements Kondo, et al. (1992) : A spallation source … is a viable candidate only if it can be attained at much less expense than the alternatives. The Materials Test Station (MTS) is a cost effective spallation source because it builds on existing infrastructure – Existing 1 MW proton linac with shared DOE sponsorship – Existing experimental hall with all needed utilities – Target designed specifically for high neutron flux irradiation

While a fusion reactor, a spallation source, and IFMIF have different spectra, materials damage is similar Spallation sources have higher recoil energies, but these ultimately yield sub-cascades similar to fusion first wall and IFMIF. We will calculate the PKA spectrum for the MTS and report at the upcoming ICFRM in Sept MTSIFMIF Fusion Reactor dpa/fpy appm He/dpa appm H/dpa transmutations in Fe appm Mn/dpa

MTS produces an intense neutron flux for fast reactor fuels and materials irradiations proton beam fuels irradiation region materials irradiation regions While being designed for fission irradiations, the MTS environment is well suited for fusion materials testing.

The MTS capital cost is a fraction of the IFMIF capital cost IFMIF cost is $900M to $1B MTS cost is $63M to $81M (1 MW baseline, funded by NE) LANSCE beam power upgrade options: 1 MW baseline 1.8 MW ($120M) 3.6 MW ($230M)

The operating cost of a spallation source should be much less than for IFMIF Annual electricity usage comparison – IFMIF: 230 million kW-h – MTS (at 1 MW, 1.8 MW, or 3.6 MW): ~40 million kW-h (800-MeV protons have 10 times greater neutron production per unit beam power than 40-MeV deuterons) Other accelerator operating costs (e.g., staff, spare parts) – IFMIF: accelerator is wholly dedicated to IFMIF target – MTS: LANSCE is a multi-target facility with shared accelerator operating costs (shared accelerator beam does not preclude 1- to 3.6-MW beam delivery to MTS)

Fission and Fusion Materials Facility: Opportunities for in-situ characterization spallation targettest fuel rodletsin-situ test specimenmaterials sample cans Move beyond traditional PIE using a 3 rd or 4 th generation light source and techniques such as diffraction, tomography, small angle scattering, xanes, and exafs to measure: – Swelling – Phase stability – Structural integrity – Corrosion – Thermal properties X-ray light source See ReNeW white paper by M.A.M. Bourke, et al.

A spallation source fully satisfies the FESACs materials qualification facility initiative Low-cost modifications to an existing US MW-class spallation source, such as MTS, provides a fusion- relevant irradiation environment with – irradiation volume on par with IFMIF – at a fraction of the capital and operating costs of IFMIF – on a time scale 5 to 10 years earlier Such a source can eliminate the need for US participation in IFMIF and put U.S. in a leadership position in fusion materials qualification What have we missed?