1. Regular cryomodule maintenance plans (radiation damage, seals, etc)
Michael Drury
SRF Operations Support
Jefferson Lab

2. Maintenance Plans - Reliability
Complete C20 Warm Window Replacement Program
Original cryomodules outfitted with polyethylene windows.
Failure rate appeared to be increasing over the last year.
Single window failure can take entire cryomodule out of service.
Replace aging polyethylene windows with ceramics
Five zones in SL completed
Ten zones left with the bulk in the SL

3. Maintenance Plans - Reliability
New hardware and procedures put in place to mitigate particulate / contaminant migration into cavities
Upgraded portable clean room
Slow bleed up pumping rig
Helium Glove bag for window change out

4. Maintenance Plans - Reliability
O-ring vacuum seal replacement program
Insulating Vacuum seal
Located in end cans at either end of cryomodule
Failure of seal in 2L17 may be due to radiation damage
Insulating Vacuum spoiled
Higher heat load
Tuners frozen
Cryomodule mostly offline

5. Maintenance Plans - Reliability
Root cause of failure at 2L17 not yet known
May be radiation related ?
May be age?
Assume for now that 2L17 first of many
Start replacing O-rings as we replace warm windows
O-ring replacement involves beamline
Potential for multiple module warm ups
Take advantage of the current large population of warm modules?

6. Maintenance Plans - Reliability
Beamline valve replacement
Viton seals degrade in radiation environment
Valves do not seal
Not a crippling failure but complicates other tasks
Forces multiple cryomodule warmups in order to access beamline

7. Maintenance Plans - Reliability
Proposal:
Find a manual all-metal valve that can be installed between girders and the B-pump drops.
Reduce need for warming up cryomodules
Could be installed between every cryomodule or between groups of cryomodules

8. Maintenance Plans - Reliability
Real Time Repairs
Insulating vacuum leaks
Broken tuners
Ion pump replacements
Turbo Pump repair replacement

9. Maintenance Plans - Reliability
Ongoing turbo pump repair and replacement
Consider purchasing more of the Agilent Twistorr 304 style pumps
Lower maintenance costs over time
Lower capacity model may be acceptable (for cost saving)
Need for LCW is a concern (air cooled model)

10. Other Support Energy Reach
Complete the microphonics hardening installations
Lead collar installations in C100 zones
Support C50 / C75 Installations
Includes installations and extractions
Girder cleaning
Commissioning
Support investigations of in-situ degaussing
Targeted Helium Processing
Process Cryomodules that have lost ground
Increased arc rates are one possible metric
Further C100 Helium Processing
Support SRFR&D efforts to understand cryomodule performance issues
C50 Waveguide trips
Field emission improvement efforts

11. Summary Current plans include Completion of warm window replacements
Begin replacing O-ring seals in parallel with other maintenance and repair activities
Support all Real Time Repair needs
Support other Energy Reach enhancing activities
While engaging in these activities:
Utilize improved hardware and procedures to mitigate particulate contamination and migration
Procure more Twistorr turbos
Investigate an all metal valve installation