ESS Cooling System - Interface with DTL 1 John Jurns Cooling System Engineer

What is the purpose of the cooling system? The cooling and heat recovery system of the ESS plant shall be designed to meet the following requirements: Provide reliable and efficient cooling of all parts of the ESS site that requires water cooling Transfer as much heat as possible from the cooling system to the city of Lund district heating system and/or other external waste heat recovery systems What systems are included in our scope of work? The scope of the cooling system design is primarily to manage the flow of heat in the technical infrastructure (i.e. – the machine). Cooling is accomplished primarily with water. Systems in scope include: Accelerator – klystron gallery and linac tunnel Target – interface at target internal cooling systems boundary Cryoplant – compressor and helium cooling Instruments – cooling as required for instruments and instrument support equipment Conventional Facility – interface with conventional HVAC

Cooling system parameters Majority of cooling provided by closed loop water-water heat exchanger and pump systems. Water temperature range approximately deg C Water system pressure nominally 10 bar Three primary cooling loops – low, medium & high temperature ranges. Total flow through each loop ~ 8000 liter/minute Primary cooling loops interface with: Substations located close to cooling loads Central utility building where cooling loops interface with external District Heating system Secondary cooling loops interface with individual cooling loads and substations Linac will have two cooling substations. One of these substations will manage heat from the RFQ and DTLs

ESS cooling system overview

ESS cooling substation locations concept Target building LINAC SC cavities cooling substation RFQ/DTL cooling substation Ion source cooling substation Central Utility building Target cooling substation Cryo cooling substation Instrument cooling substation Cryoplants Instruments To Lund District Heating

Central utilities building cooling system schematic

Cooling system distribution to ESS linac

Typical linac substation schematic LowMediumHigh

RFQ cavity Klystron gallery Tunnel Accelerator Warm end substation Accelerator cooling piping – warm end substation RFQ/DTL DTL cavity Warm end high accuracy temperature control Spokes To Central utility building ~ 94 kW cooling total 3-5 l/sec flow MEBT Ion source/LEB T 30 kW 64 kW 54 kW ? kW Cooling demand

DTL cooling ? DTL Cooling Substation TBD Interface RFQ DTL

Warm linac cooling assumptions & questions Assumptions: Both DTL & RFQ cooling require close control of temperature for operation DTL cooling estimate as follows: [2200 kW input X 2.91μS X 14 Hz X 50%] + [0,6 kW/m X 32 m] = 64 kW RFQ cooling estimate as follows: [1500 kW input X 2.91μS X 14 Hz X 50%] = 30 kW Ion source/LEBT require ~ 20 ± 1,0 deg C water, ~ 55 kW estimated cooling MEBT cooling requirements are currently undefined. Conduction Radiation

Warm linac cooling assumptions & questions Questions: MEBT cooling requirements – kW, temperature & pressure? DTL nominal cooling temperature deg C? DTL temperature control limits? That is - ± 0,1 deg C? Pressure limits for DTL? Reasonableness of heat load assumptions? DTL cooling controls & interface requirements? Cooling system architecture Ion source/LEBT, MEBT cooling direct from substation (cooling only, no temperature control) Separate dedicated cooling subsystem for DTL? Integrated cooling subsystem for RFQ & DTL? Separate fluid loop for DTL cooling, or direct supply from cooling system? If direct, any specifications on water quality?