1. n_TOF spallation target upgrade Discussion with d’Huart Industrie 24 th September 2015 M. Calviani, A. Perillo-Marcone, S. Sgobba for the n_TOF target consolidation WG

2. Introduction 24 September 2015 MC/APM/SG - Discussion n_TOF/d'Huart2  n_TOF is a neutron time-of-flight facility for neutron cross-section measurements  Neutrons are produced by impacting a high energy, high intensity proton beam on a pure lead cylinder block (99.995%), 60 cm diameter, 40 cm length (2x cores bought from d’Huart in 2008)  The beam deposits ~5-10 kW in the bulk material  target is water cooled, target core <120 °C and surface <80 °C to avoid water boiling  Un-cladded design  erosion/corrosion

3. New spallation target  We have started the study for a new spallation target – one of the objectives would be to avoid direct contact between water and lead  Reduction of circuit contamination  Possibility to “contain” lead with a corrosion resistant refractory metal (i.e. tantalum) 24 September 2015 MC/APM/SG - Discussion n_TOF/d'Huart3

4. Solutions for a Ta-contained Pb target 1.Casting lead on a prepared Ta- container, performing CIPing (cold isostatic pressing) afterwards to improve contact 2.Casting lead on a prepared Ta-container, melting a second time (with a backing jacket?) inside a vacuum chamber in order to outgas and remove impurities 3.Shrink fitting of a Pb block inside a Ta- container 24 September 2015 MC/APM/SG - Discussion n_TOF/d'Huart4

5. Open questions 24 September 2015 MC/APM/SG - Discussion n_TOF/d'Huart5  Expected soundness/purity of the casting if melted in a Ta crucible compared to the usual D’Huart practice  Before CIPing/remelting  Following these operations  Improvement in case of remelting?  Inspectability (by UT)? Which resolution for imperfections?  Which geometrical tolerances can be achieved on such a Pb cylinder?  How would help the addition of antimony?  Any experience in cooling lead parts with CO 2 ice (−78.5 °C) or liquid N 2 (- 200°C)?

6. Feedback  Do you have any feedback on the feasibility of this solution?  Can we envisage a small prototype? 24 September 2015 MC/APM/SG - Discussion n_TOF/d'Huart6

7. Thanks