Energy deposition, dose rate and activation calculations ...activation calculations for the HiRadMat24 and 27 experiments David Horvath –CERN (EN-STI) ... Base of the experiment:

Energy deposition, dose rate and activation calculations for the HiRadMat24 and 27 experimentsDavid Horvath – CERN (EN-STI)

SATIF-13, 10.10.2016

Outline

SATIF-13, 10.10.2016

1. The HiRadMat facility

2. HRMT27 experiment

1. Base of the experiment: The AD-Target

2. Experimental setup

3. Energy deposition, dose rate and activation calculations


D. Horvath - HRMT24, 27 2

CERN HiRadMat facility [1]

• High-Radiation to Materials

• Commissioned in 2011

• Proton beam from SPS

• Evaluate high-intensity beam impacts on materials and accelerator components

• Not an irradiation facility

SATIF-13, 10.10.2016 D. Horvath - HRMT24, 27 3

Outline

SATIF-13, 10.10.2016


2. HRMT27 experiment [2]






Antiproton production at CERN

• The AD-Target is the antiproton supplier at CERN

• Designed during the 80s with many variations

• With ELENA operation needs to be guaranteed for the next 20 years

• Redesign of the AD-Target is intended


The AD-Target

Current design:

• Iridium core, ⌀ 3 mm x 55 mm

• Encapsulated in a graphite matrix

• Body made of a titanium alloy

• Water cooled

Why considering a redesign?

• Extreme temperatures and stresses during operation

• Drop in antiproton yield after installing a new target

• Indicates irreversible changes in the core

• (Water cooling is not necessary anymore)


Motivation and objectives

• Motivation

• Reduce the uncertainties existing in the core material response in the AD-Target

• Asses the material selection for the new AD-Target

• Objectives

• Recreate equivalent extreme conditions (energy density and stresses) as reached in the AD-Target in a controlled environment

• Identify mechanism if failure and limits of materials of interest impacted by proton beams


Matching conditions

PS

• 26 GeV/c

• ⌀ 3 mm x 55 mm

• 0.5 mm x 1 mm @ 1 σ

• 1.45e13 proton / pulse

SPS

• 440 GeV/c

• ?

• ?

• ?


Multiple iterations of energy deposition and thermomechanical simulations were performed using FLUKA Monte Carlo particle transport code

Selected parameters

• ⌀ 8 mm x 140 mm

• 1.5 mm x 1.5 mm @ 1 σ

• Max. 1.5e12 proton / pulse

• Length depends on the density of the tested material

• 140 mm: Iridium and Tungsten

• 160 mm: Tantalum

• 240 mm: Molybdenum

• To see the changes in the materials, the beam intensity was ramped

• 8e10, 2.5e11, 5e11, 7.5e11, 1e12, 1.25e12, and 1.5e12 proton / pulse

• Each target was planned to receive 3 pulse at each intensity


Residual dose rate of the targets

• For planning the post irradiation experiments

• Conservative approximation, 5 pulse per intensity per target

• Indicates it is possible to handle the targets without a hot cell, after reasonable cooling time.


[mSv/h] 1 week 1 month 2 months 4 months 6 months 1 year

Ir 29.6 5.5 2.2 0.97 0.57 0.17

W 17.9 2.2 1.09 0.52 0.33 0.14

WL10 17.8 2.2 1.1 0.52 0.33 0.14

W + Ta 18.7 2.2 1.2 0.62 0.4 0.17

Ta 18 2 1.1 0.6 0.39 0.17

Mo 9.7 1.7 1.05 0.67 0.49 0.2

TZM 9.7 1.7 1.03 0.66 0.49 0.2

Specific activity, Exemption limit (LE)

• To determine if a material is radioactive in a legal point of view [4]

• Specific activity [MBq/cm3]

• But the limit is determined based on the separate activity of each isotope.


Rod 1 week 1 month 2 months 4 months 6 months 1 year

Ir 24.2 6.30 2.40 0.993 0.610 0.233

W 12.4 3.28 1.71 0.828 0.537 0.237

Ta 8.90 1.67 0.822 0.433 0.300 0.167

Mo 3.72 0.692 0.434 0.241 0.153 0.057

Specific activity, Exemption limit (LE)

• A LE limit is specified in the law for each isotope

• The limit is based on the number

𝑖

𝑆𝐴𝑖𝐿𝐸𝑖

• If the sum is bigger than 1 -> It is radioactive

• Each rod has to be considered as radioactive



Ir 66500 20200 9220 3840 2100 520

W 45500 12800 6130 2270 1200 415

Ta 35000 7820 4120 1800 1120 429

Mo 23800 7350 3980 1750 1040 367

Activity, Authorization threshold (LA)

• To do a destructive analysis, another limit determines the lab can be used. [4]

• Based on the total activity [MBq]

• Similarly as LE, it is based on the activity of each isotope



Ir 170 44.3 16.9 6.99 4.29 1.64

W 87.5 23.1 12.0 5.83 3.78 1.67

Ta 71.6 13.4 6.61 3.48 2.41 1.34

Mo 44.9 8.35 5.24 2.91 1.85 0.685

Activity, Authorization threshold (LA)

• A LA limit is specified in the law for each isotope

• The limit is based on the number

𝑖

𝐴𝑖𝐿𝐴𝑖

• If the sum is

• Σ < 100, class C lab can be used

• 100 < Σ < 10000, class B lab has to be used

• 10000 < Σ, class A lab needed



Ir 168 78 34 12 8 6

W 184 88 37 11 7 6

Ta 47 24 13 8 7 6

Mo 7 3 2 0.9 0.6 0.2

Residual dose rate of the experiment

• To determine the needed cooling time of the whole tank

• Changes between the simulation and the experiment

• Tank design

• Tested materials

• Different intensities

• The approval for moving the tank from the experiment hall depends on measurements

• More interesting to compare these measurements with a simulation using the final data.


Final experimental setup


Engineering model

Simulated model

Target holder


Residual dose rate of the tank


• Date of experiment: 13. Nov. 2015• Date of measurement: 19. Jan. 2016• Total of 8.424*1013 proton on target, divided among the 13 targets

• Moving target holder not easy to simulate• Solution: 26 separate simulation merged

Averaged over 1 cmaround the beam line

Measurement and simulation compared

Location Measured Simulation

1. 21 19.9 (2.1%)

2. 17 17.2 (2.7%)

3. 165 161 (3.3%)

4. 6 6.0 (2.9%)

5. 5 4.5 (3.2%)

6. 10 9.1 (3.6%)

7. 21 19.0 (3.5%)

8. 11 11.0 (2.2%)

9. 0.8 1.5 (3.5%)

10. 6 5.0 (3.2%)


Residual dose rate [μSv/h]Cooling time 68 days

Top view@ beam line

Side view@ beam line

❶

❺

❹

❸❷

❻

❿

❾

❽

❼

Outline

SATIF-13, 10.10.2016






3. HRMT24 experiment [3]


Introduction

• Collaboration with multiple institutes

• Motivation:

• To design and operate beryllium beam windows and targets in high energy particle accelerator facilities.

• Objectives:

• Explore the failing modes of different beryllium grades

• Identify potential thermal shock limits

• Compare experimental measurements with numerical simulations


Beryllium samples

• Size:

• Thin disks with thickness between 0.25 mm and 2 mm, 15 mm in diameter

• “Slugs”, 30 mm thick cylinders with 40 mm diameter

• Beryllium grades:

• PF-60, S-65F (VHP), S-200F (VHP), S-200FH (HIP)

• Organized in 4 separate arrays to test each size / grade with different beam intensities.


Beam parameters

• 440 GeV/c proton beam

• 0.3 mm @ 1 σ

• Intensity: 1.7*1011 proton per bunch

• Bunch distribution:

• Array 1: 144 bunches [9%]

• Array 2: 72 + 216 bunches (5.5 mm separation) [18%]

• Array 3: 24 + 6 x 144 bunches (same axis) [55%]

• Array 4: 288 bunches [18%]

• Total: 1608 bunches – 2.7336*1014 protons


Simulated geometry


1

2

3

4

Materials

• Structural elements:Aluminium

• Index plunger:Stainless steel

• Beam windows:Glassy carbon and Duragraph

• Gages

• Strain: Constantan strain gages

• Temperature: Nickel


Residual dose rate – 2 months cooling


Residual dose rate of “slugs”


High contribution from the index plunger and gages.

Maximum residual dose rate along beam

• Maximum:860 μSv/h

• At the tank’s wall:~ 2 μSv/h


Conclusion


• FLUKA energy deposition simulation results can be used for thermo-mechanical calculations as input

• FLUKA activation simulations can be effectively used

• To plan the cooling times for irradiation experiments

• To determine if a material has to be considered as radioactive

• To select the necessary laboratory class for destructive work on radioactive materials

• The FLUKA simulation results and the measurements are in good agreement for residual dose rates after irradiation experiments.

References

[1] HiRadMat website: http://n.ch/hiradmat/

[2] C. Torregrosa et.al. “The Hiradmat 27 Experiment: Exploring High-Density Materials Response at Extreme Conditions for Antiproton Production”7th International Particle Accelerator Conference, Busan, Korea, 8 - 13 May 2016, pp.THPMY023https://cds.cern.ch/record/2207471

[3] K. Ammigan et al. “Examination of Beryllium Under Intense High Energy Proton Beam at CERN's HiRadMat Facility”6th International Particle Accelerator Conference, Richmond, VA, USA, 3 -8 May 2015, pp.WEPTY015https://cds.cern.ch/record/2141752

[4] Swiss Federal Council: Radiological Protection Ordinance (StSV)


Acknowledgements

Marco Calviani and Claudio Torregrosa

Thank you for your attention!

Backup slide

HRMT27 - Targets after the experiment


Ir target after full intensity Impact

Longitudinal cracks in Iridium at intermediate intensities.

W after full intensity

• Tungsten targets present the larger amount of longitudinal cracks.

• Spall of fragments at the surface also took place in tungsten.

IRIDIUM

TUNGSTEN

MOLYBDENUMTANTALUM • No cracks were observed in Ta targets.

Documents

Energy deposition, dose rate and activation calculations ...activation calculations for the HiRadMat24 and 27 experiments David Horvath –CERN (EN-STI) ... Base of the experiment: