Radiation protection aspects for the Phase II upgrade
S. Roesler, C. Theis, C. Urscheler, Heinz Vincke, Helmut Vincke
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OutlineA quick introduction to FLUKAResidual dose equivalent predictions by
FLUKA◦Evolution parameters for simulation◦Focus on Inner Detectors◦Scaling factors for Phase II upgrade◦Measured dose rates and comparison to
FLUKA simulations for ATLASALARA:
◦ALARA rules◦Optimization during design (ActiWiz)
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What is FLUKA1,2?General purpose tool for
calculating transport and interactions of particles with matter
Applications: accelerator shielding to target design, activation, dosimetry, detector design, etc.
(1) A. Ferrari, P.R. Sala, A. Fasso and J. Ranft. FLUKA: amulti-particle transport code. s.l. : CERN 2005-10, INFN/TC_05/11, SLAC-R-773, 2005.(2) G. Battistoni, S. Muraro, P.R. Sala, F. Cerutti, A. Ferrari, S. Roesler, A. Fasso, J. Ranft. The FLUKA code: Description and benchmarking.
Proceedings of the Hadronic Shower Simulation Workshop 2006. s.l. : Fermilab 6-8Sept 2006, AIP Conference Proceeding 896, 31-49 (2007).
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Physics in FLUKA1,2interaction and transport of:
◦About 60 particles (non-nuclei) Photons and electrons from 1 keV to
thousands of TeV Hadrons up to 20 TeV (up to 10 PeV by
linking DPMJET3) Neutrons down to thermal energies (260 energy
groups for E < 20MeV)
Heavy ions◦In complex geometries and presence of
magnetic fields(1) A. Ferrari, P.R. Sala, A. Fasso and J. Ranft. FLUKA: a multi-particle transport code. s.l. : CERN
2005-10, INFN/TC_05/11, SLAC-R-773, 2005.(2) G. Battistoni, S. Muraro, P.R. Sala, F. Cerutti, A. Ferrari, S. Roesler, A. Fasso, J. Ranft. The
FLUKA code: Description and benchmarking. Proceedings of the Hadronic Shower Simulation Workshop 2006. s.l. : Fermilab 6-8Sept 2006, AIP Conference Proceeding 896, 31-49 (2007).
(3) S.Roesler, R.Engel, J.Ranft. The Monte Carlo Event Generator DPMJET-III. s.l. : Springer-Verlag Berlin, 1033-1038 (2001), 2000. Vols. in Proceedings of the Monte Carlo 2000 Conference Lisbon, October 23-26.
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ATLAS model in FLUKA
(4) V.Vlachoudis "FLAIR: A Powerful But User Friendly Graphical Interface For FLUKA"Proc. Int. Conf. on Mathematics, Computational Methods & Reactor Physics (M&C 2009), Saratoga Springs, New York, 2009
Pixel
Pictured with FLAIR4
• Symmetry in φ and with regard to xy plane at IP • Including magnetic field from toroid• Reduced implementation of services and support
structure
10 m
Endcap calorimeter
TAS
Q1
Endcap toroid
Original version by: A. Ferrari, modified and updated by many other authors
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CMS model in FLUKA
(4) V.Vlachoudis "FLAIR: A Powerful But User Friendly Graphical Interface For FLUKA"Proc. Int. Conf. on Mathematics, Computational Methods & Reactor Physics (M&C 2009), Saratoga Springs, New York, 2009
Pictured with FLAIR4
• Symmetry in φ and with regard to XY plane in IP except for interface to LHC• Including magnetic field from solenoid and from Q1• Reduced implementation of services and support structure• No Castor
10 m
Pixel
HE
HF
TASQ1
Blockhouse
Original version by: M. Huhtinen, modified and updated by many other authors
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Operational scenario up to Phase II
2011&2012
LS1 2015 2016 2017 LS
2 2019 2020 2021 LS3
ATLAS Lint (fb-1) 31 52 41 41 83 83 83Lpeak (cm-2s-
1) 3×1033 1.0×1034
1.0×1034
1.0×1034
2.0×1034
2.0×1034
2.0×1034
CMS Lint (fb-1) 26 50 80 100 150 150 150Lpeak (cm-2s-
1) 8×1033 1.2×1034
2.3×1034
2.5×1034
3.5×1034
3.5×1034
3.5×1034
L.Rossi / Workshop on remote manipulations, 6.Mai 2013
Assumptions on the operational parameters as obtained from ATLAS and CMS
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Residual dose rates LS3 – ATLAS
one month
1 week 6 months
one year
0.5uSv/h
0.15uSv/h
0.3uSv/h
0.11uSv/h
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Residual dose rates LS3 – CMS
one month
1 week 6 months
one year
EDMS-Nr: 1281113
5uSv/h 1uSv/h
3uSv/h 0.7uSv/h
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TRTPixelSCT
ATLAS - inner detectors implementation in FLUKA
beampipe:• Be for z<3.5m,
aluminium for z>3.5m
• No bellows includedPixel layout• : by P. Miyagawa
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1 year6 months
4 weeks1 week
ATLAS - Residual Dose in vicinity of Inner detectors LS1
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1 year6 months
4 weeks1 week
ATLAS - Residual Dose in vicinity of Inner detectors LS3
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ATLAS - Scaling factors inner detectors (0<r<1m)
LS1 LS3
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ATLAS - Scaling factors inner detectors (0<r<1m)
Average scaling factors: residual dose at different cooling times
1w 1w/4w
1w/6m
1w/1y
LS1 1 0.7 0.3 0.2LS3 1 0.8 0.4 0.3
LS1 LS3
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ATLAS - Scaling factors LS1 to LS3
Average scaling factors: Residual dose LS1 vs LS3
1w 4w 6m 1y
LS3 / LS1 7.5 8.4 11 12
Forum on Tracking Detector Mechanics 2013, 19-21 June
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beampipe:• Be for z<2m, steel
for z>2mPixel layout• : by I.KurochkinTracker layout:• Si layers, average
material for services and air
Silicon tracker
ECAL barrel
HCAL barrel
ECAL endcap
Bellows (Fe, Cr, Ni)
CMS - inner detectors implementation in FLUKA
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6 months 1 year
1 week 4 weeks
CMS - Residual Dose in vicinity of Inner detectors LS1
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1 week 4 weeks
6 months 1 year
CMS - Residual Dose in vicinity of Inner detectors LS3
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CMS - Scaling factors inner detectors (0<r<1m)LS1 LS3
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Average scaling factors: residual dose at different cooling times
1w
1w/4w 1w/6m
1w/1y
LS1 1 0.5 0.2 0.1LS3 1 0.6 0.3 0.2
CMS - Scaling factors inner detectors (0<r<1m)LS1 LS3
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Average scaling factors: Residual dose LS1 vs LS3
1w 4w 6m 1y
LS3 / LS1 11 14 21 24
CMS - Scaling factors inner detectors
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Measurement points 1-5:
ATLAS – Bechmark to measured dose rates forward regionLS1
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Measurement points 1-5 @ 40cm:
MEASUREMENT / [µSv/h]
FLUKA / [µSv/h]
1 19 14 +- 22 10 14 +- 23 7.2 11 +- 24 47 42 +- 15 42 50 +- 1
ATLAS – Benchmark to measured dose rates forward regionLS1
Measurement data from 21.2.2013 in courtesy of O.Beltramello, N. Conan, S. Malyukov, G. Spigo
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6680 (EBC)Barre
l EBC40 cm 90 cm 180
cm
VI VA
6 87
MEASUREMENT / [µSv/h]
FLUKA / [µSv/h]
6 39 167 32 148 52 29
Measurement points 6-8 @ 10cm:
ATLAS – Benchmark to measured dose ratesLS1
Measurement data from 6.3.2013 in courtesy of O.Beltramello, N. Conan, S. Malyukov, G. SpigoDose equivalent rate prediction for VA by Z. Zajacova
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Classification of non-designated and radiation areas at CERN
EDMS-Nr: 810149
IEFC workshop 2011, 21 - 24 March 26
General Principles of Radiation Protection
1) Justification
any exposure of persons to ionizing radiation has to be justified
2) Limitation
the personal doses have to be kept below the legal limits
3) Optimization
the personal doses and collective doses have to be kept as low as reasonable achievable (ALARA)
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Optimization – CERN safety code F
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Optimization is legal requirement if accumulated annualdose exceeds 100 μSv (ALARA)
Optimization includes:
Optimization is done by the Experiment safety group (RSO, Glimos) in cooperation with CERN-RP group
• work coordination• work procedures• handling tools• design • material
5 mSvGro
up 1
crit
eria
Gro
up 2
crit
eria
Group 1 criteria: determine ALARA Level classificationGroup 2 criteria: can be used by RP/RSO to increase/decrease classification depending on radiological risk analysis
Formal work-and-dose-planning(DIMR) as from ALARA Level 2
ALARA committee if ALARA Level 3
Optimization – ALARA procedure
Methodology:1. Calculation of residual dose rate maps
2. Calculation of individual and collective intervention doses
3. Revision of design and/or work scenario
• for cooling times typical for interventions on the respective component• based on nominal operational parameters• definition of geometry and materials as detailed as needed (and available)
• Done by Experiment safety group (RSO, RPE, Glimos) approved by RP• based on as realistic as possible work scenarios, including locations, duration, number of persons involved,..• identification of cooling times below which work will be impossible (design criterion: 2 mSv/intervention/year)
• start with work steps that give highest individual or collective doses• consider optimization measures (distance, tooling, material choices, etc.)• identify if remote handling is possible
Optimization during design – Intervention doses
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Optimization starts with the design!
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Goal:• Minimize doses received by personnel during maintenance and repair• Reduce costs for waste disposal
Consider radiological hazards in the choice of construction materials
Tool to optimize material choices:
ActiWiz5 Computer code implementing a risk model using pre-calculated FLUKA results. Considers external exposure and radioactive waste disposal Provides radiological hazard assessment for arbitrary materials within a few seconds Catalogue6, produced with ActiWiz, listing pre-processed risk factors for typical accelerator construction materials as well as natural elements Web-based catalogue (ActiWeb) allowing user friendly comparison of pre-processed materials
Web-site: https://actiwiz.web.cern.ch/
Optimization during design – Material choice
(5) H. Vincke, C. Theis: “ActiWiz - optimizing your nuclide inventory at proton accelerators with a computer code, Proceedings of the ICRS-12 & RPSD 2012 conference, Nara, Progress in Nuclear Science and Technology, in press, 2013.(6) R. Froeschl, S, Sqobba, C. Theis, F. La Torre, H. Vincke, N. Walter: “Radiological hazard classification of material in CERN’s accelerators”, EDMS-Nr: 1184236
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ActiWiz web-based catalog
Pictures from: ActiWeb by F.L. Pereira, C. Theis, H. Vincke, (c) CERN 2011
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Pictures from: ActiWeb by F.L. Pereira, C. Theis, H. Vincke, (c) CERN 2011
ActiWiz web-based catalog
ActiWiz is designed for
LHC accelerator scenarios,
Keep in mind when using
for experiments
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Materials not available in the catalogue can be processed with ActiWiz
ActiWiz – Material Catalogue
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Optimization during design – ActiWiz
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Summary and Conclusion Ambient dose equivalent rate around inner detectors
for Phase II: up to 100 µSv/h after several months of cool down time
Scaling factors from LS1 to LS3 between 8-12 for ATLAS and 12-24 for CMS, depending on the cooling time
Benchmark with ATLAS measurements indicates factor of 2 for most locations with exceptions at local hotspots due to inaccurate geometry implementation
Future work: update FLUKA geometries including changes during LS1 (aluminium beampipe, implementation of missing flanges etc.)
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Backup slidesLS2
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6 months 1 year
4 weeks1 week
Residual Dose in vicinity of ATLAS Inner detectors LS2
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1 week 4 weeks
Residual Dose CMS Inner Detectors LS2
6 months 1 year
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BACKUP SLIDES ATLASResidual dose only pixelResidual dose only ID-SCT-TRT
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Residual Dose ATLAS Pixel LS1
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Residual Dose ATLAS Pixel LS3
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Residual Dose ATLAS ID-SCT-TRT LS1
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Residual Dose ATLAS ID-SCT-TRT LS3
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Waste zoning CMS
https://edms.cern.ch/document/1286671/1
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Waste zoning ATLAS
https://edms.cern.ch/document/1286661/1