1. ESS Cryogenic Distribution System for the Elliptical Linac CM - CDS requirements Preliminary Design Review Meeting, 20 May 2015, ESS, Lund, Sweden J. Polinski

2. L4-CDS-MBL_010 The physical interface between the CDS and medium beta cryomodules shall include the connection of a four-channel branch cryoline (jumper connection) and the connections of the cryomodule auxiliary process lines to the SV relief line, the recovery line and the purge return line. CTL Aux. Lines Valve Box

3. L4-CDS-MBL_020 Connection between the vacuum jackets of the cryomodule and valve box shall be demountable The connection will be realized with a demountable bolted flange

4. L4-CDS-MBL_025 The leak rate through the vacuum jacket connection shall not exceed 1.0E-10 mbar*l/sec The specified max leakage level is a few orders of the magnitude too low for the large-diameter elastomer seals. This value should be revised. NASA Technical Note D-4394, An Investigation of o Large- dimeter O-ring Seals On Spacecraft Air-lock Hatches

5. L4-CDS-MBL_030, 040 Connection between the process pipes of the cryomodule and valve box shall be permanently welded Connection between the process pipes of the cryomodule and valve box shall allow for cutting and rewelding at least two times such that no cutting shavings and/or chips will get into the process pipes. Using the special designed welding flanges on the process pipes

6. L4-CDS-MBL_035 The leak rate through each pipe connection shall not be higher than 1.0E-10 mbar*l/sec 1.Appropriate welding technique, 2.Non-destructive (X-ray, leak tightness) test after the weld realization

7. L4-CDS-MBL_050 The vacuum barrier that separates the insulation vacuum of the cryomodule and cryogenic distribution system shall be located in the jumper connection on the CDS side. 1.Appropriate design, 2.Inspection during the installation

8. L4-CDS-MBL_055 The leak rate through the vacuum barrier shall not be higher than 1.0E-8 mbar*l/sec Leak tightness test during the production and commissioning

9. L4-CDS-MBL_060 Process pipe connections in the valve box jumper connection shall allow for adjustments of +/- 15 mm radially w.r.t. the pipe center line and + 20/- 35 mm longitudinally w.r.t. the process pipe interface plane For process pipes up to DN10 - using the pipe elasticity, for larger pipe size - application of the elastic hose.

10. L4-CDS-MBL_070 Vacuum jacket (external envelope) in the valve box jumper connection shall allow for adjustments of +/- 5 mm radially w.r.t. vacuum jacket center line and +/- 10 mm longitudinally w.r.t. the vacuum jacket interface plane Using the bellows in the valve box jumper connection vacuum jacket

11. L4-CDS-MBL_080 The thermal shield inlet line (BE) shall supply helium at a maximum operating temperature of 45 K 1.Requirement of 38K temperature helium inlet to the TS Supply line from the ACCP side ACCP-CDS-L4-190 2.Limitation of the heat flux to the CDS ME process line by the mechanical optimization of the pipe support system, 3.Thermo-mechanical optimization of the supports design and appropriate thermal insulation system design. 4.Requirement of the specific helium flow at the inlet to the CDS ME line from the ACCP side.

12. L4-CDS-MBL_090 The thermal shield inlet line (BE) shall supply helium at a maximum operating pressure of 19.5 bara 1.Requirement of max 19.5 bara of helium pressure at inlet to the TS Supply line from the ACCP side - ACCP-CDS-L4-210 2.Calculation of the pipe wall thickness in accordance with EN 13480-3

13. L4-CDS-MBL_100, 110 The thermal shield inlet line (BE) shall supply helium a minimum operating mass-flow of 0.93 g/s (nominal operation) The thermal shield inlet line (BE) shall supply helium a minimum operating mass-flow of 2.2 g/s (cool-down phase) Calculation of the required cross-section area (diameter) of the BE and ME lines with respect of allowed flow pressure drop. Verification method – Measurement??? -TBD

14. L4-CDS-MBL_120, 130 The thermal shield circuit shall be protected by a safety valve with a set pressure of xxx barg The thermal shield circuit shall be protected by a safety valve with a minimum relieving diameter equal to xxx This information shall be provided by the CM manufacturer by the end of the June 2015

15. L4-CDS-MBL_140 The supercritical inlet line (BC) shall supply helium at a maximum operating temperature of 5.5 K – contradiction with CDS-HBL-L4- 050 where Tmax is 5.2 1.Requirement of 4.5K temperature helium inlet to the He Supply line from the ACCP side ACCP-CDS-L4-060 2.Limitation of the heat flux to the CDS MC process line by the mechanical optimization of the pipe support system, 3.Thermo-mechanical optimization of the supports design and appropriate thermal insulation system design. 4.Requirement of the specific helium flow at the inlet to the CDS MC line from the ACCP side.

16. L4-CDS-MBL_150 The supercritical inlet line (BC) shall supply supercritical helium at a maximum of 3 bara 1.Requirement of max 3.0 bara of helium pressure at inlet to the He Supply line from the ACCP side - ACCP-CDS-L4-080 2.Calculation of the pipe wall thickness in accordance with EN 13480-3

17. L4-CDS-MBL_160 The supercritical inlet line (BC) shall supply helium at a minimum operating mass-flow of xxx g/s 1.Calculation of the required cross-section area (diameter) of the MC and BC lines with respect of allowed flow pressure drop. 2.The mass flow shall be provided by the CM manufacturer by the end of the June 2015

18. L4-CDS-MBL_160 The supercritical inlet line (BC) shall supply helium at a minimum operating mass-flow of xxx g/s 1.Calculation of the required cross-section area (diameter) of the MC and BC lines with respect of allowed flow pressure drop. 2.The mass flow shall be provided by the CM manufacturer by the end of the June 2015

19. L4-CDS-MBL_170 Vapor Low Pressure (VLP) line (BB) shall return helium at a maximum operating pressure of 30 mbara Calculation of the pipe wall thickness in accordance with EN 13480-3

20. L4-CDS-MBL_180 CM safety valve relief lines (BS3 and SS2) shall return helium at a maximum operating pressure of 1.1 bara Calculation of the pipe wall thickness in accordance with EN 13480-3

21. L4-CDS-MBL_190 CM safety valve relief lines (BS3 and SS2) shall return helium at a maximum operating mass-flow of xxx g/s 1.Calculation of the required cross-section area (diameter) of the pipe with respect of allowed flow pressure drop. 2.The mass flow shall be provided by the CM manufacturer by the end of the June 2015

22. L4-CDS-MBL_200 Power-coupler return line (SR1) shall return helium at a maximum operating pressure of 1.1 bara Calculation of the pipe wall thickness in accordance with EN 13480-3

23. L4-CDS-MBL_210 Power-coupler return line (SR1) shall return helium at a maximum operating mass-flow of xxx g/s 1.Calculation of the required cross-section area (diameter) of the pipe with respect of allowed flow pressure drop. 2.The mass flow shall be provided by the CM manufacturer by the end of the June 2015

24. L4-CDS-MBL_220 Cavity purge return line (SP) shall return helium at a maximum operating pressure of 1.1 bara Calculation of the pipe wall thickness in accordance with EN 13480-3

25. L4-CDS-MBL_230 The allowable working pressure of the VLP return line, measured at the valve box side of the heat exchanger, shall be minimum 1430 mbar(a) (Requirements valid during warm up and cool down phases) Calculation of the pipe wall thickness in accordance with EN 13480-3