1. ISOLDE Front-End design review – Details of previous faults
AP.Bernardes on behalf of EN-STI-RBS team
Acknowledgements: B.Conde Fernandez, K.Kershaw, S.Marzari, M.Delonca

2. Design Review Frontends Isolde
Outline
Failures
Target valves and FE shutters
Extraction electrodes
Coupling table
Cables
Others
Summary
Conclusion
15 June 2016
Design Review Frontends Isolde

3. Design Review Frontends Isolde
Target valve failures
Indicators
Estimation
Frequency
>1 per year
Collective dose impact
2015: 1.4mSv
2014: none …
Physics impact
Low
Every year several targets are found not fully closed (identified before target transfer to ISR)
Not possible to identify the position with precision (no sensor no switch)
Most of the times, target can be removed without problem by the robot
15 June 2016
Design Review Frontends Isolde

4. Design Review Frontends Isolde
FE shutter failures
Indicators
Estimation
Frequency
≈ 1 every year
Collective dose impact
2015: 1.4mSv
Low
Physics impact
Failure may be due to previous target shutter failures? (target O-Rings out of position)
Not possible to identify the position with precision (no sensor no switch)
15 June 2016
Design Review Frontends Isolde

5. Target and FE shutters failures
Failures origin
Compressed air (pollution, insufficient pressure, etc.)
Lack of valves lubricant
Target O-Rings out of position
Air leak on FE shutter piston (reduce strength)
Wrong calibration of FE shutter piston
No precise indicator for these failures
15 June 2016
Design Review Frontends Isolde

6. Extraction electrodes failures
Indicators
Estimation
Frequency
≈ 1 every 3 years
Collective dose impact
Medium
Physics impact
Position identified
Mechanical system not fully accessible (only first part)
15 June 2016
Design Review Frontends Isolde

7. Extraction electrodes failures
Failures origin
Loosened screws
Default on gears
Wrong calibration of extraction electrode
Extraction electrode felt from support (No end-stop)
FE shutter closed on extraction electrode (No interlock)
Extraction electrode position identified but not precise enough some time to understand the failures
15 June 2016
Design Review Frontends Isolde

8. Coupling tables failures
Indicators
Estimation
Frequency
>1 per year
Collective dose impact
Medium
Physics impact
New design in 2014, optimized in 2016
Position identified with switch and potentiometers since 2016 (do not allow to know if the target is ”vacuum" clamped  Reduce gas storage capacity )
Piston fully accessible and fast to repair design
15 June 2016
Design Review Frontends Isolde

9. Coupling tables failures
Failures origin
Air leak on coupling table piston (reduce strength)
Lack of clearance on coupling table movement
Lack of clearance on potentiometer axis
Misalignment of coupling table
Wrong calibration of coupling table
Coupling table position identified but but not precise enough some time to understand the failures
15 June 2016
Design Review Frontends Isolde

10. Design Review Frontends Isolde
Cable damages
Cable damages due to irradiation and some mechanical constraints:
Cables not easy to change if needed, no fast repair design
15 June 2016
Design Review Frontends Isolde

11. Design Review Frontends Isolde
Others
Radiation damage to material
Corrosion
15 June 2016
Design Review Frontends Isolde

12. Summary Failure Frequency Collective dose impact Physics impact
Target valves
>1 per year
2015: 1.4mSv
2014: none …
Low
FE shutters
≈ 1 per year
Extraction electrodes
≈ 1 every 3 years
Medium
Coupling table
Cables
Standard hazards on target area (preventive maintenance)
Others
15 June 2016
Design Review Frontends Isolde

13. Design Review Frontends Isolde
Conclusion
Most of FE failures come from mechanical movement
Mechanical movement should be suppressed or reduced as much as possible
If not possible mechanical movement should be as simple as possible
Moveable parts should be placed outside in order to be accessible for visualization or repair and fast intervention
When possible moveable parts should be designed to be repaired with Telemax
When possible back-up solution should be envisaged
15 June 2016
Design Review Frontends Isolde