design and challenges for the ship target complex

Design and challenges for the SHIP target complexM. Calviani, A. Ferrari, R. Losito, A. Perillo-Marcone, R. Folch, V. Venturi Engineering Department (EN)Sources, Targets and Interactions (STI) Group

First SHIP Workshop – 10-12 June 2014 - Zurich

M. Calviani - Design and challenges for the SHIP target complex

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Outline SHIP target station design

Preliminary thoughts and challenges SHIP production target

Issues and present conception Conclusions and perspectives

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Target areas at CERN CERN target areas are generally halls, pits or long tunnels,

far from the access points Activated air has enough time to decay and stray radiation is not

a problem for the public Neutrino ones are generally deep in the molasses (e.g. CNGS)

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beam

WANF & CNGSAntiproton target

n_TOF (neutrons)TCC2


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SHIP target station design The SHIP TS

preliminary design takes advantage of the activities for CENF

Shallow target installation, multi-compartment solution

Underground areas accessible from the target hall

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Due to the shallow depth of the beam line (~14 meters), a target area approach based on long tunnels (i.e. CNGS, WANF, etc.) is not applicable

A multi-compartment solution similar to T2K/NuMI has been therefore developed, taking into account the specificities of CERN


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Features of the SHIP target station Production target installed inside an

underground Fe shielded bunker, accessible from the top

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Iron shielding to be water cooled (~O(100 kW))


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Features of the target station Fully remote handling/manipulation of the

target and shielding from the target hall High residual dose rate (~tens of Sv/h!)

Helium environment enclosing the target and the shielding Reduction of air activation and corrosion

Ventilation system according to ISO17874 The idea is to have a pressure dynamic

confinement

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M. Battistin (EN/CV)


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This is what happens w/o control of the air chemistry (~at 20 kW)


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Target hall above ground level Outside area shall be non-designated during target

manipulation Ground-filled around target hall or heavy concrete walls

An additional (smaller) service building needed Safety racks, EL cabinets (EBD, etc.), transformers,

water treatment area, access, etc.


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View of the target hall and service buildings

Radioactive areas, no access

Radioactive areas, accessible in shutdown

Access for transport and various additional services (EL, secondary water loops, etc.)

38 m

35 m


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Target station summary Target station shall be designed for a MW-

class spallation target Specific attention to radioprotection &

environmental releases – well mastered and evaluated for CENF CE works adapted to minimize water infiltration

and in case treatment with evaporators Shall be designed for long-term operation Minimize time for target exchange in case of

failure (physics downtime)

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Challenging… but feasible


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Target design The production target is the single most

critical aspect of the target complex As required by the experiment, W-based (i.e.

high-Z) target Long term reliability is a key factor in the

design Reduction of “waste” Reduce downtime to minimum

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(Spallation) source

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One of the most technologically challenging aspects of the proposed installation In terms of average beam power on target would be

similar to SNS (USA) or MLF (JP) However, power during pulse would make it closer to

ESS (almost 3 MW) Baseline UltimateBeam protons protonsMomentum [GeV/c] 400 400Beam Intensity [1013 p/cycle] 4.5 7.0Cycle length [s] 7.2 8.4Spill duration [s] 1.0 2.2Expected r.m.s. spot size (H/V) [mm] 6/6 6/6Average beam power on target [kW] 400 530Average beam power on target during spill [kW] 2900 2030B

eam

par

amet

ers


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Analysis method

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Analysis assumes nominal operation, with both the baseline and ultimate beams Steady state with transient analysis

Worst case scenario, i.e. target reaches steady state and then receives a high intensity pulse

Main preliminary results: Full W cylinder will not withstand the

compressive stresses (>2 GPa) and temperatures (>1200 °C) – target would fail

Target segmentation mandatory to allow decrease of temperatures and thus stresses


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Energy deposition and checks

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FLUKA/ANSYS/CFX coupled calculations Pure tungsten, 19.3 g/cm3

60 cm length, 20x20 cm2

Beam on target:1. Uniform circular sweep 3

cm radius, 1s 6 mm2. Archimedean spiral, 5-35

mm radius (1s 6 mm) 80% energy deposited in

the target (300-400 kW)

Target must be actively cooled(H2O considered for the

moment)


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Preliminary

Preliminary

Optimisation of the plate thickness still ongoing Longitudinal gap of

~O(10-15 cm) Peripheral + radial

cooling to increase HTC

High tangential velocities (5-10 m/s)!


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Thermo mechanical calculations Considering the poor properties of W heavy alloys

to high temperature and radiation we baselined pure W

~780 °C, 900 MPa (worst case) R&D needed!!!

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Caveat: Conservative

assumptions Still lots of margins

for improvement!


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Accident scenario (no sweep)

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3000 °C (below melting point at ~3400 °C)

~4.4 GPa compressive stress

The target would not melt... But will fail!


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Radiation damage Design shall assume that a target withstands the

whole proposed POTs (2*1020) ~1.2 DPA (displacement per atom) at 2*1020 POT

Big impact on the evolution of mechanical properties!

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Evolution of mechanical properties with radiation (and temperature)

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S. A. Maloy et al., ICANSXX workshop (2012) S. A. Maloy, Materials Transactions, Vol. 43, No. 4 (2002)

Yield stress increases with irradiation and decreases with temperature

Reduction of ductility with irradiation


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Crack formation on pure W samples under irradiation

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S. A. Maloy et al., ICANSXX workshop (2012)S.A. Maloy et al. / Journal of Nuclear Materials 343 (2005) 219–226

The central core of the SHIP target might potentially develop internal cracks due to radiation embrittlement, swelling and high temperature


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Target design preliminary assessment

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The target must be segmented to reduce temperatures and compressive stresses

Very high flow rate required (cavitation, erosion/corrosion...) Need to check “water hammer” effect on target/cooling

circuits Full control of water chemistry (à-la-n_TOF) Vigorous R&D should be launched on material

properties and their evolution with radiation and temperature Ta-cladded W, WRe alloys, K-doped W alloys, etc.


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Possible other uses? We are considering a 500 kW (3 MW

pulsed) class spallation source Possible additional uses with minor

additional investments: Neutron/photon irradiation close to the target

~100-200 MGy/y lateral, 400 MGy/y downstream Neutron beam(s) for different applications (i.e.

neutron radiography) laterally outside of the He vessel (@500 cm or more)

…

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Conclusions

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Target design is very challenging (but feasible!), significant R&D required on material and technical work for CFD and code optimization

Target station design needs to account the high average power (hence radioprotection and handling aspects) Profit from CENF studies but a dedicated WG

will be needed towards the DR

We are looking forward for this project!


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