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Description
SCK CEN is developing MYRRHA, a large-scale Accelerator Driven System (ADS). MYRRHA shall be a subcritical nuclear reactor driven by a high-power linear proton accelerator (600 MeV @ 4 mA), which sustains the nuclear reaction. In the initial phase, known as the MINERVA project (100 MeV @ 4 mA LINAC), the goal is to demonstrate the high reliability requirements on the accelerator as required for an ADS.
This work reports a joint development between ESS Bilbao and SCK CEN in developing the MINERVA 17 MeV injector beam dump and the 100 MeV tuning beam dump (a.k.a. DUMP-OT) concept for proton beam-tuning operations. A unified design approach satisfies both beam dumps requirements by leveraging consistent average power (4 kW) and pulse duration (4 ms), while accommodating peak powers of 68 kW and 400 kW respectively. The concept meets ultrahigh-vacuum (UHV), activation and waste-management constraints and is designed for long operational life. The assembly is intended to be installed inside a shielded, activated cave with no possibility for readjustment and maintenance after installation. It ensures safe, repeatable superficial deposition of the beam through a shallow grazing angle (≈5–6°). Design and operational requirements (UHV compatibility, activation management and long-term robustness) guided the material selection and the mechanical layout.
The principal technical innovation is a modular first-wall composed of discrete CuCrZr “mushroom” elements. The proposed configuration consists of 48 independent CuCrZr mushrooms, each mechanically fastened (M24 nut + washers) to a common water-cooled CuCrZr plate with embedded cooling channels. Each mushroom features a head, neck and shank geometry optimized to control local heat fluxes and to reduce peak thermal stresses; the mechanical preload of the bolt ensures axial contact while a designed discontinuity at the interface tunes heat transfer and accommodates differential thermal behaviour. This modular, bolted design concentrates the beam load into independent elements while conducting heat into the common water-cooled block via the embedded channels, enabling effective thermal management under reduced duty-cycle operation.
Structural and thermo-mechanical verification has been performed using finite element models of the DUMP-OT assembly (316L vessel and piping), using an equivalent mass representation for internal components and detailed material data for CuCrZr. The finite element analyses confirm the integrity of the vessel and support the recommended fixation and support strategy to avoid local stress concentrations. Material selection and modelling have been carried out accounting for CuCrZr’s thermal and mechanical behaviour under the expected operating temperatures and loads.
Prototyping and component-level studies confirm the feasibility of the mushroom-based concept (thermal performance, bolted contact mechanics, thermocouple instrumentation and monitoring, cooling circuit suitability) and inform the final Integration & Testing and manufacturing strategy for a first-wall able to withstand the proton beam footprint. The modular CuCrZr mushroom and water-cooled plate approach provides a flexible and thermally efficient solution for beam dumps in MINERVA-like facilities.
Keywords: Beam dump; MINERVA; MYRRHA Phase I; beam tuning; CuCrZr; mushroom; water-cooled plate; ultrahigh vacuum; FEA; thermo-mechanical analysis; prototype
| Other | Beam Dumps |
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