The assessment of individual and collective intervention doses for the LHC beam cleaning insertions M. Brugger, D. Forkel-Wirth, H. G. Menzel, S. Roesler (SC/RP)

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

ObjectivesRaise awareness about the necessity to begin optimization already now - the respective groups of concern will need time to define their needs in order to implement the optimizations before the startup of the machineIdentify critical interventions in order to suggest improvements and perform possible optimizationsPrepare the staged machine installation (collimator upgrade, vacuum, kickers, etc) during the first years of LHCPrepare contracts in time: external companies intervening in high radiation areas have to be certified (i.e. respective constraints will have to be included in market surveys)Collect input for documentation (INB reports) which has to be soon submitted to the French authorities for LHC approval. They will include estimates for individual and collective doses (one of the major concerns of the authorities!)Detailed Monte Carlo simulations are available for IR7 (arbitrary locations, different cooling times)Applying a new method (developed by RP) to calculate remanent dose rates based on the explicit production of radionuclides and the simulation of their decay particles. This overcomes the old limitations due to conversion coefficients only valid at contact to large surfaces.

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

You have to look closeNot to miss the details

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

To Avoid Surprises

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

To Be Prepared

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Regions with low losses(e.g. due to residual gas)Regions of point losses(e.g. Collimators,)*picture by T. WijnandsLHCGoal: Critical individual and collective doses for the LHC (including experiments)

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Beam OperationExpected Intensities/LossesFirst Year (2007): Start with low intensities, 1.3x1016 particles lost at IR7 (both beams)Second Year (2008): 25ns Operation, still limited intensities, 2.1x1016 particles lost at IR7 (both beams)Third Year (2009): Install MKBs, Upgrade to phase 2, Pushing up the intensity, Probably at Nominal around the end of the year -> 2.1x1016 4.1x1016 particles lost at IR7 (both beams)Fourth year (2010) xxx (20xx): Operate at around Nominal intensity -> 4.1x1016 particles lost at IR7 (both beams)xxx year (20xx): Push the machine to its maximum and operate at around Ultimate intensity, unlikely without further changes of the machine layout -> 7.3x1016 particles lost at IR7

Possible Operational PeriodsBreakdown of a year into shutdown and operational periods (e.g. 4 months / 8 months)Breakdown of operational periods into beam-on and beam-off periods (e.g. 25 day beam run / 3 days off)Breakdown of beam periods into physics and other runs (e.g. 1 day setting up, 4 days MD and 20 days physics* M. Lamont* R. Bailey

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Beam Operation - ConsequencesAs compared to nominal operation one can assume the following scaling factors with respect to losses during the first years of operation:1st year: 1/32nd year: 1/2 4th - xxx year: 1Afterwards (???): 2 With respect to expected operational periods of the machine access due to interventions might be necessary at the following cooling times:Urgent repairs when LHC is operating: 1 - 8 hoursRepairs during beam-off period:8 hours 3 daysInterventions during shutdown:1 day 4 months

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Which are the Constraints?

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Radiation Protection Legislation: General PrinciplesJustificationany exposure of persons to ionizing radiation has to be justified

2) Limitationthe individual doses have to be kept below the legal limits

3) OptimizationDynamic Process: the individual doses and collective doses have to be kept As Low As Reasonably Achievable (ALARA), i.e. iterations are necessary between the intervening groups and RP in order to reduce individual and collective doses to a reasonable minimum

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Limits per 12-months period (mSv)

Public

Exposed Workers

B

A

EURATOM

< 1

< 6

< 20

France

< 1

< 6

< 20

CERN

< 0.3

< 6

< 20

Switzerland

< 1

< 20

Corresponding Constraints

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Monte Carlo Calculations(FLUKA)

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Calculation ProcedureDetailed Geometry description includingCorrect source terms including primary loss distributionComplete geometryTunnel structure, Collimator, magnetsBeamline, Dogleg separationMonte-Carlo simulation using the new Explicit Method to calculate dose rate maps for the entire geometry and various cooling times, includingSuccessfully benchmarked method: at CERF and during the TT40 testsExtensive set of simulations (several thousands NCU days!)Separate simulations for different contributorsAverage and Maximum Values for relevant locationsResults are calculated per lost proton and can be scaled with the respective lossesTypical operational period of 180 days and cooling times ranging from one hour to four monthsCompilation of intervention scenarios together with the corresponding groupsTime, location and frequency of the interventionNumber of persons involvedCalculation of individual and collective dosesIteration and optimization

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Dose Rate Maps for the Different Cooling Times1 hour8 hours1 day1 week1 month4 monthsResults are normalized for one LHC year (180 days) running at nominal intensity.Aisle: 1-4mSv/hClose: 2-20mSv/hAisle: 0.5-2mSv/hClose: 2-20mSv/hAisle: 0.1-1mSv/hClose: 1-10mSv/hAisle: 0.1-0.5mSv/hClose: 0.5-5mSv/hAisle: 0.05-0,3mSv/hClose: 0.1-3mSv/hAisle: 0.01-0.1mSv/hClose: 0.1-1mSv/h

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Intervention Scenarios - IR7 only The following scenarios have already been identified and/or studied in more detail.

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Intervention Scenarios - DetailsTo study various maintenance scenarios in order to get a complete view of individual and collective doses at IR7 we need the following information:

Kind of interventionLocation of the interventionTypical cooling period before interventionNumber of persons involvedSteps of the intervention Time estimate for each step (including location)Annual frequency of the interventionAre external contractors involved

At the moment the uncertainty lies in the estimates for the intervention(s), not in the calculation of the remanent dose rates!

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Example: Exchange of Collimators(Collimator, Vacuum, RP, Beam Instrumentation?,)

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

How will it look like ?*R. Perret et al Narrow, thus difficult access e.g. Exchange of motor on the tunnel side position in case of a tilted collimator

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Individual Doses

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Exchange of CollimatorReminder: CERN Design criterion - 2 mSv/person/intervention*Scenario O. Aberle

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Collimator Exchange -Vacuum SystemVacuum: Collimator exchange - Summary of different scenariosTotal accumulated dose per person in mSvReminder: CERN Design criterion - 2 mSv/person/intervention*Scenario M. Jimenezusing chain clamps reduces the individual dose to 2/3dismounting the second beam-line would almost double it

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

BakeOut/NEG Coating - Vacuum Reminder: CERN Design criterion - 2 mSv/person/intervention*Scenario M. Jimenezpermanent bakeout equipment would gain about a factor of 5 with respect to the individual and collective dose

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Collective Dose

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Collimator Exchange All Steps

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Collimator Exchange Collective Dose

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Collimator, Exchange Prel. ConclusionsValues refer the most radioactive collimator (1st secondary) and to nominal intensity not to be reached during phase 1. They can be scaled by a factor of two for the first years of operationHowever, collimator supports and additional material not included in the simulation will however increase individual and collective dosesIn addition, after installation of phase 2 even higher doses have to be anticipated due to the hybrid collimators (e.g., copper jaws) The results and scenarios have to be further discussed and refined in order to become as realistic as possibleWithout improvements long down times will have to be accepted (at least for those collimators showing the highest remanent dose rates)Chain clamps and permanent bakeout equipment will certainly improve the situation (the latter will have to be radiation hard)

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

How do these values compare to current interventions at CERN and the SPS?

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Comparable InterventionsAs compared to the values above, we do face significantly higher individual and collective doses at IR7 (e.g., collimator exchange: 1d 1w cooling: 6-25 mSv)

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

How to obtain to a realistic annual dose estimate?

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

- tendency to lower doses during the last years- future major contributors: CNGS, LHC (not only IR7),- future increase of intensities will also result in higher annual doses of the PS and SPS Annual Doses SPS, CERN100-700mSv/year300-1500mSv/year* J. C. Gaborit, G. Grobon, E. CenniniS P SCERN

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Chart1

37.78408.9

306.11483.3

182.26583.5

458.7840.9

745.9865.6

184.25598.7

210.46414.9

198565

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353.5658.8

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259.6535.7

259.6471.4

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190.5315

392513

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84.37120.86

Dose collective pour le complexe SPS de 1977 2002

Dose shutdown

Dose totale

Dose intgre en mSv

annual

Dose shutdownDose totale

7737.78408.9

78306.11483.3

79182.26583.5

80458.7840.9

81745.9865.6

82184.25598.7

83210.46414.9

84198565

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91277517

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93353.5658.8

94223.9486.18

95315568

96259.6535.7

97259.6471.4

98188327

99190.5315moyenne/personne

00392513542personnes003925135420.95

01224.6261.6470sur393shutdown01224.6261.64700.56

0284.37120.86370l'anne0284.37120.863700.33

&A

Page &P

annual

Dose collective pour le complexe SPS de 1977 2002

Dose shutdown

Dose totale

Dose intgre en mSv

repartition

0 - 0,5292

0,5 - 144

1 - 224

2 - 36

3 - 43

4 - 51

5 - 60

&A

Page &P

repartition

402

53

34

21

11

7

9

4

1

0

Total enregistred people : 542 Total integrated dose : 512,8 mSvAverage dose : 0,946 mSvHighest dose : 8,252 mSv

Dose in mSv/an

Number of persons

Repartition of the personnels doses in 2000

quater

Nombre de personnes enregistres : 370 Dose totale intgre : 120,86 mSvDose moyenne : 0,327 mSvDose la plus leve : 4,213 mSv

Dose en mSv/an

Nombre de personnes

Rpartition des doses personnelles en 2002

Sheet4

&A

Page &P

Sheet4

13.6661.60.365.566

25.4037.3844.0757.391

5.2470.5120.320.737

1.360.20.0770.319

0.54BA50.1460.216

33.8840.3450.8111.074

49.25BA7BA71.217

200.0558.783.371.288

10.7121.0840.796BDW

51.75617.21915.4818.747

Tests LHC4.7214.7330.856

1st quarter

2 nd quarter

3 nd quarter

4 nd quarter

Dose in mSv

Repartition of the collective dose in the SPS complex per area and per quarter

Sheet5

&A

Page &P

&A

Page &P

Annual Doses Prel. ConclusionsPhase 2 installation will become a critical interventionDetails need to be clarifiedFor a complete assessment of annual doses to be expected at IR7 iterations are still necessary with the respective groupsreceive missing informationdiscuss the available resultsrefine the scenarios (locations, time)clarify expected frequency of interventionsFor the LHC we suggest to develop scenarios forthe first years of operationphase 2 installationgood yearsafter 5-10 years of operationbad yearWhen compared to current annual doses for the SPS and CERN it is obvious that further optimization is important

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Important Issues & ConclusionsOptimization: what has been achieved so far for IR7:No local heavy shielding (not remotely removable)Reorientation of magnetsPlug-in system for collimators (fast exchange), Fast connect flanges for vacuum, ?What is currently being done:Identify most critical scenarios, calculate individual and collective dosesGet a first impression about annual dosesImportant issuesINB reports for LHC approval (including provisional estimates for individual and collective doses)Mock-up installations and precise intervention planning, the latter is legally requiredIn case of critical interventions in high radiation areas external companies have to be certified (i.e., constraints will have to be included in market surveys)What will have to be done:Before startup: further optimization, improvements, development of work procedures, iteration with calculations, mock-ups During the first years: validation using measurements, scaling of simulations, detailed maintenance planning, dose evaluation

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

What we would like to avoid:waiting too long and then have to use detours

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Cause this would lead to:bad and certainly dangerous surprises:And not only authorities would

get angryUuups

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

ConclusionsOptimization: what has been achieved so far for IR7:No local heavy shielding (not remotely removable)Reorientation of magnetsPlug-in system for collimators (fast exchange)Fast connect flanges for vacuumWhat is currently being done:Identify most critical scenarios, calculate individual and collective dosesGet a first impression about annual dosesIteration with groups of concern, identify possible improvementsWhat will have to be done:Before startup: further optimization, improvements, development of work procedures, iteration with calculations, mock-ups During the first years: validation using measurements, scaling of simulations, detailed maintenance planning, dose evaluation

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Thank You

The assessment of individual and collective intervention doses for the LHC beam cleaning insertions

Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field Facilitymention IR3Markus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityTuecke des Objekts cussedness of thingsMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field Facilitymention IP3, Experiments, Dump, TripletsMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field Facilityuse comparison to speed limits -> RP limits are never to be exceeded nor to be reached!describe clearly the process of optimizationMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field Facilitymention that the 2mSv/person/intervention are only for high-rad areas . otherwise much lower!Markus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field Facilityno detailsMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field Facilityreminder: - most radioactive collimator- phase 1 (graphite) without supports- nominal beam intensity

Markus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003Measurements and Simulation of Induced Activity at the CERN-EU High Energy Reference Field FacilityMarkus Brugger - AccApp2003