Distributed Optical Fibre
Radiation and Temperature
Sensor (DOFRS)
Iacopo Toccafondo, EN-EA
Outline
• Introduction & Motivations
• Distributed Optical Fiber Radiation Sensor
(DOFRS) based on RIA
• Distributed radiation measurements at
CHARM
• PSB Installation & Further Work
Introduction
Concerns
• High radiation levels
• Ensuring reliability and safety of the accelerator complex
• Equipment groups rely on accurate dosimetry for lifetime prediction
Currently
• Monitoring systems
• Designing and installing radiation
resistant components
• Regular maintenance,
replacement/relocalization
Limitations
• Monitoring systems are discrete/punctual, only partially online
• Frequent maintenance due to conservative life estimation approach
Motivation
• Provide accurate online distributed dosimetry
• Increasing safety
• Cost-effective implementation
• Future collider projects
=> Necessity of a cost-efficient,
implementable and performant
solution!
Concept - Distributed measurements
Conventional (discrete)
• Online monitoring
Optical Fibre Based
(distributed)
• < 1m spatial resolution
Distributed OTDR radiation sensing at
CHARM
• 130 m long fibre path
Target
• Two heights around the
shielding:
95 cm & 280 cm above ground
• Wide range of dose rates
Optical Fibre
Adapted from the CHARM facility webpage
Equipment: EXFO FTB500 with two high dynamic range OTDR modules
 SMF (850 nm & 1300 nm) & MMF (1310 nm & 1550 nm)
 Available pulse duration: 5 ns up to 20 µs
 Measurement time: 30 s up to 180 s
Distributed OTDR radiation sensing at
CHARM
•
J-fiber MMF, pulse width: 10 ns, acquisition time: 30 s, Al-h target
•
Correct detection and localization •
of the four major dose peaks
Detecting dose variations down to
10-15 Gy
Distributed OTDR radiation sensing at
CHARM
•
J-fiber MMF, pulse width: 10 ns, acquisition time: 180 s, Cu target
After 10 h 37 min
Distributed OTDR radiation sensing at
CHARM
•
J-fiber MMF, pulse width: 10 ns, acquisition time: 180 s, Cu target
After 16 h 37 min
Distributed OTDR radiation sensing at
CHARM
•
J-fiber MMF, pulse width: 10 ns, acquisition time: 180 s, Cu target
After 25 h 57 min
Test installation in the PSB
First in-field deployment at CERN: installation in the Proton
Synchrotron Booster (PSB)
• Targeting full coverage (~157 m)
• Dose range from few tens Gy/y
up to 100 kGy/y
Up to a factor
10 reduction
J.P. Saraiva and M.Brugger,
“CERN-ACC-NOTE-2015-0042”, 2015
• Post LS2, LINAC4 => reaching 2 GeV!
Test installation in the PSB - Status
• Approved Engineering Change Request (ECR)
• Installation of a metallic structure to support control
RACK during week 37
• Installation of RACK and fibre infrastructure during the
EYETS 2016-2017
• Installation and testing of equipment, end of EYETS
2016-2017
Further Work – Fibre Selection
• Characterizing commercial optical fibres
• At CC60 and CHARM facilities (CERN)
• Outside: Fraunhofer INT, others
• Purchasing from Fibrecore (P-doped cladding) and LEONI, any other?
• Corning doesn’t have any radiation sensitive fibre
• Draka (Italy) neither...
• OFS has a does rate dependency
• Characterizing optical fibres from ixBlue
• Fibres co-designed by LHCurien St-Etienne => highly promising
• PCe fibres – starting 14/09/2016 at CHARM
• P-doped => testing at CHARM?
• HACC => testing at CHARM?
• Designing optical fibres with ixBlue and LHCurien
Development of customized control unit Status
• Meeting with Scuola Superiore Sant’Anna and INFIBRA
Technologies held in Pisa on the 27/05/2016 =>
discussed two possible approaches
• Control unit: necessary hardware and software developed and
configure to control two commercially available sensors =>
OTDR + Raman DTS
=> Market survey being carried out to assess if commercially
OTDR boards are available and at what cost - ongoing
• Hybrid solution: adapting an existing highly performant Raman
DTS developed by INFIBRA to be also used as OTDR
=> photobleaching effects due to coding need to be assessed
– to be started
Development of customized control unit Status
• Acquisition, data processing and results visualization
interface, currently being developed in Python ongoing
• EN/STI-ECE will take over the LabView implementation
of the above and TIMBER logging => useful both for
PSB and possibly for the custom control unit
Many thanks for your attention!
[email protected]