What need to be done to restart n_TOF (in 2007?) 4 Short description of the Facility 4 Old Target removal in the provisional Storage place (Service Gallery)

What need to be done to restartWhat need to be done to restart n_TOF (in 2007?) n_TOF (in 2007?)

Short description of the FacilityShort description of the Facility

Old Target removal in the provisional Storage Old Target removal in the provisional Storage place (Service Gallery).place (Service Gallery).

New Target Design and ConstructionNew Target Design and Construction

Ventilation of the Target AreaVentilation of the Target Area

Target Repository for the new TargetTarget Repository for the new Target

SummarySummary

Presented by P. Cennini Presented by P. Cennini n_TOF Technical Coordinatorn_TOF Technical Coordinator

ATC-ABOC Days, CERN 22-24 January 2007ATC-ABOC Days, CERN 22-24 January 2007

n_TOF n_TOF Short DescriptionShort Description


The main characteristics of the Facility are:The main characteristics of the Facility are:

• Broad Neutron Energy Spectrum: Broad Neutron Energy Spectrum: @@1 eV to 250 MeV1 eV to 250 MeV• High Integral Neutron Flux: High Integral Neutron Flux: 6.26.2101055 n/cm n/cm22/7/710101212p (uncollimated)p (uncollimated)• Long flight path: Long flight path: 187.5 m187.5 m• Very good Energy Resolution:Very good Energy Resolution:0.05 % at 1 keV 0.4 % at 1MeV, 2 % at 100 0.05 % at 1 keV 0.4 % at 1MeV, 2 % at 100 MeV.MeV.

• nn_TOF is a neutron source used for the measurement by _TOF is a neutron source used for the measurement by TTime ime OOff F Flight light of neutron induced reactionsof neutron induced reactions• The neutrons are produced by the impact (spallation) of a The neutrons are produced by the impact (spallation) of a 20 GeV/c20 GeV/c proton beam on a proton beam on a lead Targetlead Target..

n_TOF n_TOF Short DescriptionShort Description


n_TOF n_TOF Short Description:Short Description:The neutron flux at the Measuring StationThe neutron flux at the Measuring Station


Neutron Energy, log10(E) [eV]

Neu

tron

flu

x [d

n /

dlog

E /

cm

2 /pu

lse

Pb r=40 cm l= 40 cm 5 cm H2O Moderation

TOF @ 1 eV 16 ms

TOF @ 100 MeV 1.6 µs

n_TOF n_TOF Short Description:Short Description:Energy Resolution & proton BeamEnergy Resolution & proton Beam


7710101212 proton bunch @ 20 proton bunch @ 20 GeV/cGeV/c

RMS RMS 7 ns 7 ns

Protons on Target: Protons on Target: 3.5x103.5x1013 13 pp distributed in a distributed in a SUPERCYCLESUPERCYCLE (16.8 s long) in (16.8 s long) in DEDICATED MODEDEDICATED MODE (7x10 (7x101212 p/bunch) or in p/bunch) or in PARASITIC MODEPARASITIC MODE (4x10 (4x101212 p/bunch).p/bunch).

10-2

10-1

10-1

1 10 102

103

104

105

106

107

108

Energy(eV)

Dl(m)

n_TOF n_TOF Geographical SituationGeographical Situation


Dimensions: 80 Dimensions: 80 80 80 60 60 cmcm33

Pure Lead: 4 tPure Lead: 4 t

HH22O moderator: 5 cmO moderator: 5 cm

Al-window: 1.6 mmAl-window: 1.6 mm

Al-container: 140 lAl-container: 140 l

The Lead TargetThe Lead Target


Target HandlingTarget Handling


• The Target must be moved from TT2-A to the Depository in the Service Gallery. The Target must be moved from TT2-A to the Depository in the Service Gallery. • This operation is done through the Shaft by using the Hoist System.This operation is done through the Shaft by using the Hoist System.• A system using several video cameras is used for the remote control.A system using several video cameras is used for the remote control.

Old Target Removal:Old Target Removal:Present Status.Present Status.


• Shielding in the Shaft: Shielding in the Shaft: removedremoved

• Direct measurement of the dose rate: Direct measurement of the dose rate: done done (~15 mSv/h max)(~15 mSv/h max)

• Simulations of the Target activation and dose mapping: Simulations of the Target activation and dose mapping: donedone(results in agreement with the measurement)(results in agreement with the measurement)

• Risk analysis for the removal Risk analysis for the removal (EDMS 771843)(EDMS 771843): : donedone

• Operating Procedure Operating Procedure (EDMS 774982)(EDMS 774982): : donedone

• Dose rate estimation for the Procedure Dose rate estimation for the Procedure (EDMS 774982)(EDMS 774982): : donedone

Old Target Removal:Old Target Removal: What need to be doneWhat need to be done


• Problem: Problem: reliability of the Hoist Systemreliability of the Hoist SystemThe probability of failure of the existing system is considered too high.The probability of failure of the existing system is considered too high.

• Solutions:Solutions:• Installation of a new Crane with improved reliabilityInstallation of a new Crane with improved reliability

This solution has been already investigated. An offer in the framework of This solution has been already investigated. An offer in the framework of the “Contrat de maintenance Equipement de Levage et de Transport” is the “Contrat de maintenance Equipement de Levage et de Transport” is available.available.(Cost 320 kCHF, delivery time 19 weeks)(Cost 320 kCHF, delivery time 19 weeks)

• Modification of the existing CraneModification of the existing CraneThe feasibility of a solution requiring a mechanical design validated by SC-The feasibility of a solution requiring a mechanical design validated by SC-GS in the framework of GS in the framework of Code D1-7.2Code D1-7.2, has been investigated , has been investigated (EDMS 787079).(EDMS 787079).

• Independently on the adopted solution, Independently on the adopted solution, the infrastructure and the the infrastructure and the procedure for the Target recovering in case of stacking of the Hoist System procedure for the Target recovering in case of stacking of the Hoist System must be provided.must be provided.

(According with(According with informal discussions with SC-GS)informal discussions with SC-GS)

The New Target:The New Target:Motivation & Design OptionsMotivation & Design Options


• Why a new Target for n_TOF?Why a new Target for n_TOF?To avoid the contact between the lead and the cooling waterTo avoid the contact between the lead and the cooling water

• Considering:Considering: The The activationactivation of the shielding around the Target Area. of the shielding around the Target Area. The The timetime needed to remove and reinstall the shielding (6 months). needed to remove and reinstall the shielding (6 months). The “cost” of the received dose to do this operation The “cost” of the received dose to do this operation (ALARA).(ALARA). The short time schedule (expected n_TOF restart mid August The short time schedule (expected n_TOF restart mid August

2007)2007) The The “Gained Experience”“Gained Experience” with the old Target with the old Target

• Two lines have been investigated:Two lines have been investigated:1.1. Cladded lead TargetCladded lead Target cooled with the existing cooling system cooled with the existing cooling system

2.2. New designNew design (tungsten, tantalum, air cooling, …) (tungsten, tantalum, air cooling, …)

• The The Cladded Lead TargetCladded Lead Target solution is envisaged at the present time. solution is envisaged at the present time.• The access to the Target area is done via the shaft without the need to The access to the Target area is done via the shaft without the need to

remove the shielding in TT2-Aremove the shielding in TT2-A

The New Target:The New Target:Design SpecificationsDesign Specifications


Neutron Flux: Neutron Flux: unchangedunchanged Target materialTarget material: : leadlead Target cladding:Target cladding: aluminum alloy, stainless steal or zircalloy.aluminum alloy, stainless steal or zircalloy. Target cooling:Target cooling: water (existing system)water (existing system) Target dimension:Target dimension: ~ 100 liters, ~1.3 tons (cylindrical shape)~ 100 liters, ~1.3 tons (cylindrical shape) Moderation:Moderation: water / heavy water / borated water (exchangeable)water / heavy water / borated water (exchangeable) Useful n-beam diameter at the exit of the target:Useful n-beam diameter at the exit of the target: 40 cm40 cm Orthogonal flight-path:Orthogonal flight-path: foreseenforeseen 2.2 MeV 2.2 MeV flash: flash: optimized (10 %), by replacing the Moderator.optimized (10 %), by replacing the Moderator. Decommissioning: Decommissioning: this aspect is taken in account.this aspect is taken in account.

• Due to a very Due to a very low activationlow activation, , transparency to neutrons transparency to neutrons (allowing the (allowing the use of thick walls)use of thick walls) and metallurgical compatibility with the lead and metallurgical compatibility with the lead , the , the use of an aluminum alloy for the cladding and the support structure use of an aluminum alloy for the cladding and the support structure should be privileged .should be privileged .

The New Target:The New Target:Flux Simulations, GeometryFlux Simulations, Geometry


H2OOld Target H2O D2O

pp

Case studiedCase studied

The New Target:The New Target:Flux SimulationsFlux Simulations


Old Target H2O

New Target H2O

Ratio New/Old

Considering the advantages of a smaller Target dimension,

(decommissioning, handling)

the flux reduction is acceptable

Moderator thickness 5 cm

~4.4 tons of lead

~1.3 tons of lead

The New Target:The New Target:GeometryGeometry


p beam

Lead

Cooling WaterModerator ContainerH2O or D2O

Cladding

Existing Cooling Basin (aluminum)

The New Target:The New Target:Simulations, Energy DepositionSimulations, Energy Deposition


The New Target:The New Target:Simulations, Thermal StudySimulations, Thermal Study

Transient elasto-plastic study in progress


The New Target:The New Target: What need to be doneWhat need to be done


Visual Inspection of the old Target and sample analysis to Visual Inspection of the old Target and sample analysis to verify the verify the feasibility of the design optionsfeasibility of the design options..

Learn from the gained experience on the old Target after 5 years of run Learn from the gained experience on the old Target after 5 years of run (~ 6 x10(~ 6 x101919 protons on target) protons on target)..

Visual Inspection of the Cooling basin and the connection piping to the Heat Visual Inspection of the Cooling basin and the connection piping to the Heat Exchanger to Exchanger to verify theverify the possibility to use the existing Cooling Systempossibility to use the existing Cooling System. In . In case of serious contamination, the cleaning of the system should be case of serious contamination, the cleaning of the system should be envisaged.envisaged.

The two actions require the availability of a HOIST SYSTEMThe two actions require the availability of a HOIST SYSTEM

Finalize the Design Study. Several Finalize the Design Study. Several solutions are investigatedsolutions are investigated and, if needed, and, if needed, some specifications could be reconsidered like the implementation of the some specifications could be reconsidered like the implementation of the moderator exchange.moderator exchange.

Conclude the Conclude the Simulations Simulations (neutron flux, energy deposition) for the final (neutron flux, energy deposition) for the final DesignDesign

Write-up of the Write-up of the Safety FileSafety File (peer review) (peer review) Activation and Dose-rate Simulations in view of the Activation and Dose-rate Simulations in view of the Permanent DisposalPermanent Disposal..

Ventilation of the Target Area:Ventilation of the Target Area:Ventilation ParametersVentilation Parameters


Ventilation of the Target Area:Ventilation of the Target Area:Simulations ParametersSimulations Parameters


• Isotope production yield:Isotope production yield: simulated with FLUKA (39 isotopes considered)• Target material:Target material: Lead Lead (dimensions of the old Target)• Target Shielding: Target Shielding: unchangedunchanged• Irradiation time:Irradiation time: 6 months/year• Proton intensity:Proton intensity: 55x 7 7x10101212 p/supercycle p/supercycle• Protons on target:Protons on target: 3.2xx1019 p (previous runs 1.3x1019 p)

• Dose to the publicDose to the public– Definition of critical groups (border guards)– Calculation of dose conversion coefficients based on environmental models

• Investigated Solutions:Investigated Solutions:- Continuous Laminar Flow- Continuous Laminar Flow- Enclosed volume with recirculation and Flush Before Access- Enclosed volume with recirculation and Flush Before Access

Ventilation of the Target Area:Ventilation of the Target Area:Simulation ResultsSimulation Results


The Estimated Dose for the Critical Group produced by The Estimated Dose for the Critical Group produced by nn_TOF during a yearly run of 180 days at the maximum _TOF during a yearly run of 180 days at the maximum allowable proton intensity is:allowable proton intensity is:

• Continuous Laminar Flow :Continuous Laminar Flow : ~ 1µSv ~ 1µSv (~0.25 nSv/h)(~0.25 nSv/h) ****

• Flush Before Access:Flush Before Access: ~~ 0.01 µSv/flush0.01 µSv/flush

**** Dominated by Dominated by 77Be, Be, 32,3332,33P and P and 4141Ar.Ar.

Ventilation of the Target Area:Ventilation of the Target Area: Layout for the minimum Release ScenarioLayout for the minimum Release Scenario


RP Monitor

Ventilation of the Target Area:Ventilation of the Target Area: FeasibilityFeasibility


• Location of the ventilation Location of the ventilation machinery: ISR-I8machinery: ISR-I8

• Location of the Radiation Location of the Radiation Measurement Station: ISR-I8Measurement Station: ISR-I8

• Release of the air: top of the Release of the air: top of the ISR hill (at sufficient altitude)ISR hill (at sufficient altitude)

Main CharacteristicsMain Characteristics

• Permanent air circulation in Permanent air circulation in the Target Areathe Target Area

• Continuous filtering (efficient Continuous filtering (efficient capture of capture of 77Be and Be and 32,3332,33P)P)

• Monitoring of the released air Monitoring of the released air

Ventilation of the Target Area: Ventilation of the Target Area: What need to be doneWhat need to be done


The The release to the Public release to the Public close to the detection level of close to the detection level of nn_TOF, _TOF, is reachableis reachable (probably not distinguishable from the variations of the (probably not distinguishable from the variations of the natural background)natural background)..

Optimization could be studied, Optimization could be studied, economic and social factors economic and social factors being taken in account (reduced full scenario).being taken in account (reduced full scenario).

The solution adopted will be in The solution adopted will be in conformity with the global conformity with the global Agreement between CERN and the Host StatesAgreement between CERN and the Host States. .

Repository for the New Target Repository for the New Target What need to be doneWhat need to be done


At the date there is only one place in The Service Gallery to At the date there is only one place in The Service Gallery to store (temporarily) a Target.store (temporarily) a Target.

The place for an additional Storage Place for a radioactive The place for an additional Storage Place for a radioactive device is available.device is available.

The procedures for the final disposal of the old Target outside The procedures for the final disposal of the old Target outside CERN are under discussion with the CERN are under discussion with the Swiss Authorities and PSISwiss Authorities and PSI..

The possibility to do this operation in 2007 or 2008 subsist, The possibility to do this operation in 2007 or 2008 subsist, making available the existing place to store the new Target in making available the existing place to store the new Target in the near future (if needed).the near future (if needed).

ThereforeTherefore

The construction of the new Repository could be postponedThe construction of the new Repository could be postponed

What need to be done to restart n_TOFWhat need to be done to restart n_TOFSummarySummary


TitleTitle DescriptionDescription GroupGroup FTEFTEkCHFkCHF

Old Target RemovalOld Target Removal New Crane Purchase New Crane Purchase AB-ATB AB-ATB 320 320 Video Remote ControlVideo Remote Control AB-ATBAB-ATB 0.05 0.05 50 50

Old Target RemovalOld Target Removal Modification Existing Crane Modification Existing Crane AB-ATBAB-ATB 0.1 0.1 50 50

SC-GSSC-GSTS-ICTS-IC

New Target New Target Design & Production Design & Production AB-ATB 1.5AB-ATB 1.5 230230

Simulations (neutronics) Simulations (neutronics) AB-ATBAB-ATB 0.5 0.5

Target Area Ventilation Target Area Ventilation Civil EngineeringCivil Engineering TS-CETS-CE 40 40

(full scenario)(full scenario) Ventilation System DesignVentilation System Design TS-CVTS-CVAir Recirculation SystemAir Recirculation System TS-CVTS-CV

35 35Air Extraction SystemAir Extraction System TS-CVTS-CV

35 35Environmental MonitoringEnvironmental Monitoring SC-RPSC-RP

90 90New target Disposal (CERN)New target Disposal (CERN) Repository ConstructionRepository Construction TS-CETS-CE

100100

Experimental AreaExperimental Area Alignment System Alignment System AB-ATBAB-ATB 0.25 0.25 30 30

TotalTotal AB-ATBAB-ATB 2.8 2.8 1080 1080

(2.55) (2.55) (630) (630)

Target Permanent DisposalTarget Permanent Disposal Infrastructure DesignInfrastructure Design AB-ATBAB-ATB 0.3 0.3 150 150RadioprotectionRadioprotection SC-RPSC-RP 0.2 0.2SimulationsSimulations AB-ATBAB-ATB 0.2 0.2

What need to be done to restart n_TOFWhat need to be done to restart n_TOFSummarySummary


TitleTitle DescriptionDescription GroupGroup FTEFTEkCHFkCHF

OperationOperation Re-Installation n_TOF BeamRe-Installation n_TOF Beam AB-ATBAB-ATB 0.3 0.3AT-VACAT-VAC 0.15 0.15

5 5 TS-ICTS-IC 0.3 0.3 15 15

TS-CVTS-CV 0.05 0.05TS-SUTS-SU 0.05 0.05

RadioprotectionRadioprotection SC-RPSC-RP 0.3 0.3

TotalTotal AB-ATB AB-ATB 0.3 0.3 20 20

Option 1Option 1 - - New Crane, New Target, New Target Repository, Ventilation, Old Target New Crane, New Target, New Target Repository, Ventilation, Old Target Definitive Disposal, Alignment System:Definitive Disposal, Alignment System:

FTEs AB-ATB FTEs AB-ATB 3.13.1, Budget 1100 kCHF, Budget 1100 kCHF

Option 2Option 2 - - Modification Old Crane, New target, Ventilation, Old Target Definitive Modification Old Crane, New target, Ventilation, Old Target Definitive Disposal:Disposal:

FTEs AB-ATB FTEs AB-ATB 2.952.95, Budget , Budget 650 kCHF650 kCHFEstimations presented to the ATC

08.12.2006

Documents

What need to be done to restart n_TOF (in 2007?) 4 Short description of the Facility 4 Old Target removal in the provisional Storage place (Service Gallery)