Overview of the ESS Linac Cryogenic Distribution System Jaroslaw Fydrych Cryodistribution Project Engineer ESS Cryogenic Safety Workshop, Lund, February 10, 2016

Outline Introduction Layout of Cryogenic Distribution System CDS flow scheme and Valve box PIDs Cryogenic Distribution Line (CDL) design Specification of the CDS safety devices Sizing of the CDS safety devices Summary

ESS cryogenic system block diagram Pure Helium Gas Storage 1 20 m3 LHe Tank Standalone Helium Purifier Helium Recovery System Gas Storage 2 Accelerator Cryoplant Test & Instrument Cryoplant 5 m3 LHe Tank Target Moderator LHe Mobile Dewars Test Stand Cryodistribution System Instruments & Experiments LN2 Storage Tanks LN2 Mobile Dewars Accelerator Cryodistribution System Cryomodules Test Stand Lund 2 Target Cryodistribution System Hydrogen Circulation Box Hydrogen Moderator

Linac CDS – function and layout Cryogenic System of the ESS Linac 21 High Beta Cryomodules (174 m) 9 Medium Beta Cryomodules (75 m) 13 Spoke (54 m) Linac Cryoplant Superconducting section of the Optimus linac (303 m) Layout Cryogenic Distribution Line (310 m) comprising 43 valve boxes Endbox Cryogenic Transfer Line (65 m) Splitting box Auxiliary process lines Cryogenic Distribution System for the ESS linear accelerator is intended for delivering the cooling power from the linac cryoplant to the cryomodules by means of the constant flows of supercritical and cold gaseous helium, at 4.5 K and 40 K, respectively.

Linac CDS – general flow scheme 30 elliptical cryomodules 13 Spoke cryomodules Two main cryogenic circuits: - Cold helium circuit (Helium supply line + VLP line) - Thermal shield circuit (TS supply line + TS return line) + 4 auxiliary process lines:  Helium recovery line (cold)  HP line (warm)  SV relief line (cold)  Purge line (warm)

30 elliptical cryomodules CDS-EL Valve box PID Valve box for the elliptical cryomodule The heat exchanger, JT and filling valves are in the cryomodule! 30 elliptical cryomodules 13 spoke cryomodules

30 elliptical cryomodules CDS-SL Valve box PID Valve box for the spoke cryomodule The heat exchanger, JT and filling valves are in the valve box! 30 elliptical cryomodules 13 spoke cryomodules

CDS isometric view Auxiliary process lines Jumper connection Valve box Modular structure of the cryogenic distribution line! Interface to the ACCP Auxiliary process lines Jumper connection Valve box Interconnection Cryoline Interface to cryomodule

CDS-EL valve box conceptual design Valve box for the elliptical cryomodule

CDS-EL valve box conceptual design – process lines 10 layers of MLI on cold process lines Sliding supports of main process lines Fixed support Vacuum barrier Side process lines Interface to the cryomodule Cryogenic control valves VLP line He supply line Thermal shield return line Thermal shield supply line Valve box piping

CDS-EL valve box conceptual design – thermal shield Cryoline thermal shield Valve box thermal shield Shield sliding supports Bottom plate (demountable) Thermal shield of cryoline interconnection (demountable) at the cryomodule interface (demountable) Jumper connection thermal shield 30 layers of MLI on thermal shield

CDS-EL valve box conceptual design – external envelope Cryoline vacuum jacket (DN550) Valve box vacuum jacket Cryoline support Bottom plate (demountable) Cryoline interconnection sleeve with axial compensator (DN600) Interconnection sleeve at the interface to the cryomodule Jumper connection vacuum jacket with lateral compensators (vertical: DN350 horizontal: DN450 ) supports

Specification of the CDS safety devices 65 m 310 m

Specification of the CDS safety devices Initial sizing (according to EN4126) given in ESS-0011735 (CDS-EL spec) and ESS-0017178 (CDS-SL spec) In-kind Partners requested for verifying the sizing 65 m 310 m

Specification of the CDS safety devices Initial sizing (according to EN4126) given in ESS-0011735 (CDS-EL spec) and ESS-0017178 (CDS-SL spec) In-kind Partners requested for verifying the initial sizing 65 m 310 m Requirements given in the CDS specs (ESS-0011735 and ESS-0017178)

Sizing of the CDS safety devices Two failure scenarios 1. Cold process line ruptures 2. Vacuum vessel breaks on ACCP cold box on valve boxes on End box

Sizing of the CDS safety devices Two failure scenarios 1. Cold process line ruptures 2. Vacuum vessel breaks VLP line ruptures (Dh = 273 mm) Cold helium flows into the vacuum vessel insulation space Cold helium absorbs heat from the radiation shield and external envelope Cold helium temperature and pressure increase Safety valves SV71 get open Cold helium flows to the ESS tunnel Evolution of pressure in the vacuum jacket on ACCP cold box Cold helium flow rate thought 43 SV71 valves (do = 85 mm) on valve boxes 43 safety valves SV71 do = 85mm on End box

Sizing of the CDS safety devices Two failure scenarios 1. Cold process line ruptures 2. Vacuum vessel breaks VLP line ruptures (Dh = 273 mm) Cold helium flows into the vacuum vessel insulation space Cold helium absorbs heat from the radiation shield and external envelope Cold helium temperature and pressure increase Safety valves SV71 get open Cold helium flows to the ESS tunnel Vacuum vessel safety valve is accidentally open (human error) Air flows into the vacuum space and condenses/solidifies on the inner cold surfaces Cold helium in the process lines absorbs the heat from air Pressure in the process line increases Process line safety valves get open Cold helium flows to the vent lines at the cold box and end box Evolution of pressure in the vacuum jacket Evolution of pressure in the TS return line on ACCP cold box SV91 do = 35 mm SV92 do = 14 mm RD92 do = 45 mm SV93 do = 9 mm SV94 do = 20 mm Cold helium flow rate thought 43 SV71 valves (do = 85 mm) Cold helium discharge thought SV14 and SV94 (do = 20 mm) SV11 do = 35 mm (> 25 mm) SV12 do = 14 mm (= 14 mm) RD12 do = 45 mm (< 85 mm) SV13 do = 9 mm (< 11mm) SV14 do = 20 mm (>11mm) on valve boxes 43 safety valves SV71 do = 85mm on End box

Summary The main parts of the Linac CDS are Cryogenic Transfer Line (65 m) and Cryogenic Distribution Line (310 m). The cryolines contain 4 cold process lines (2xDN50, DN65 and DN250) and share one common insulation vacuum (375m, DN550). Each process line will be protected against excessive pressure by two pressure safety devices located at the line ends. The CDS vacuum jacket will be equipped with 43 safety valves located on the CDL external envelope. Sizing of the CDS pressure safety devices is well advanced but still in progress.