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

2. 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

3. 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

4. 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.

5. 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)

6. 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

7. 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

8. 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

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

10. 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

11. 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

12. 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

13. Specification of the CDS safety devices
65 m
310 m

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

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

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

17. Sizing of the CDS safety devices
Two failure scenarios
1. Cold process line ruptures 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

18. Sizing of the CDS safety devices
Two failure scenarios
1. Cold process line ruptures 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

19. 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.