The ESS Target Station F. Mezei ESS target division NPPatLPS, 2013

Target lay-out Cold moderator performance Bi-spectral beams Beam-line layout optimization Target technology Contents

3 Accelerator proton beam window (replaced every ~ 6 months) Target wheel (7 t, replaced every ~ 5 y) Moderator-reflector plug (30 t, replaced every ~ 1 y, shown in position ready for vertical extraction) Target lay-out Opportunities for steady improvements

4 Hands on access Single neutron beam window Example: LANL Lujan center Handling by vertical extraction

5 Target wheel: 33 ISIS like targets Same radiation load as ISIS and Lujan Center

Volume moderator: implemented at J-PARC 99 % para-H 2 tested 6 High performance cold moderator

7 Comparison of calculated ESS flat top brightness (red) to 2002 reference Proton beam parameters: 2.86 ms, 14 Hz, 125 MW peak General pulse shaping technology available and tested: M. Russina et al. Journal of Physics Conference series, 340 (2012) ~ 50 x ILL yellow book High performance cold moderator

8 Bi-spectral moderator / extraction Wide wavelength range increases scientific applications Several options considered Top view Thermal neutrons Cold neutrons HZB: thermal source = Be reflector

Fluid:Light Water Structure material:Al 6061-T6 Inlet Pressure:3 bar Inlet Temperature:20°C Average Volumetric Heat H 2 O:6.5 W/cm³ Average Volumetric Heat Al:9.9 W/cm³ Max. Local Temperature:46°C H 2 moderator cooling at 20 K:32 kW inst. Cost of cryoplant:15 M€ Engineering Design by FZJ

10 Favorable performance offered already by the Be reflector without extra adjustment (as in Berlin). HZB Berlin Bi-spectral moderator / extraction

11 ILL yellow book spectra: cannot be real, rather with a factor 2 ESS Bi-spectral moderator / extraction

Optimized beam-line layout Reactors: group of guides in about ° sectors. Standard at pulsed spallation sources: beam extraction sectors cover some 240   flux reduced by much reflector removed ESS approach: group beam-lines on 5  grid to minimize flux loss. Optimization flexibility available for the lifetime of the facility Brightness depends on the total angle of the opening (i.e. brightness with one 120° opening is about the same as with two 60° openings)

Proton beam Access to MR plug Beam-line & monolith layout Courtesy: FZJ Removable shielding blocks 5  grid of possible beam line positions (plugged or open) Shutter drives Dimension according to current baseline Housing for target drive and bearing

Beam-line & monolith layout

In-pile guide plug Primary shutter 174 mm width ESS primary shutter options considered Choppers (mag. b.) 5.5. m T O chopper Diagnostics shutter Target Division Curved guide with secondary shutter only

Prototype, Jülich, ~1984 Water cooling: fine for SNQ (50 kj/pulse) and in 1980's. But: - ESS: 350 kj/pulse  ~ 130 K temperature jump  boiling? - BNL (~2000): W + water vapor  H 2 + airborne W-oxide + heat (> 700 C) - Afterheat: same reaction  hydrogen explosions in Fukushima ESS backup: water cooling need to address NPP safety issues 17 Rotating target: simplest way to distribute heat deposition and afterheat in order to make cooling possible at ESS power level: a breakthrough pioneered by FZJ, SNS second target station. (Rotation period: 2-3 s) ESS baseline: He cooling Environmental safety: legal priority

He cooling is well developed/being developed: - high temperature NPP - fusion research - 4th generation NPP - transmutation using spallation (ADS) AGATE: 3 MW spallation 100 MW total

Temperature [  C] Rotating target temperatures due to afterheat (10 hours after loss of cooling), Unpublished SNS study Environmental safety: legal priority Critical target temperature for water reduction H2OH2O He Critical target temperature for solidity of structure

Target timeline Technical Design Report: Dec 2012: feasibility, costing Q3 2014: Optimization complete, design frozen Q3 2018: Manufacturing, installation complete April 2019: Ready for comissioing with beam: beam delivery starts Q2 2020: Routine operation

Thank you!