Shielding calculations with MCNPX at the European Spallation

Shielding calculations with MCNPX at the European Spallation Source R. Bevilacqua, L. Tchelidze, G. Muhrer and E. Pitcher European Spallation Source ESS, Lund, Sweden SATIF-12, April 28 -30, 2014

Outlook • Just one slide on flux-to-dose conversion • Front End Building shielding design at ESS • A short digression on 13 C(p, xn) • Study to reduce ESS Monolith’s radius • If time allows: two slides on mctal 2 root (how to analyze mcnp results with root) Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

flux to dose conversion Flux to dose (µSv h-1 cm 2 s) mcnpx 2. 7 calculations o mcnpx built-in: • ICRP-21 1971 (DEFAULT) • ICRP-74 1996 (ambient dose equivalent) o we used the Maximum of the conversion factors from ICRP-116 elaborated from ICRP 116 (same method for γ flux to dose) neutron energy (Me. V) Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Radiation areas at ESS Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Front End Building (FEB) Water cooling room o preliminary study: • • two concrete walls 40 cm thickness each < 3 µSv/h o dose limit 3 µSv/h corridor Accelerator’s tunnel MEBT 3 2 DTL TANKS RFQ 1 Front End Building

Front End Building (FEB) o Components modeled with mcnpx 2. 7 • RFQ • MEBT • DTL Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

RFQ Proton beam loss: 1 Watt m-1 RFQ length: 4. 6 m Proton Energy: 3. 6 Me. V MCNPX model Dose in water cooling room with 40 cm concrete wall Cu 0. 13 µSv/h neutron 4. 6 W point loss gamma dose: comparable Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

MEBT collimator (one of 3) [Medium Energy Beam Transport] collimator chopper dump (detail) Cu o 3. 6 Me. V protons 1014 o protons on collimators 1. 70 o protons on chopper dump: 5. 68 1014 o protons on beam pipe: 7. 0 1012 Riccardo Bevilacqua Graphite (2 mm) SATIF-12, April 28 -30, 2014

MEBT max neutron dose at surface, water cooling room • chopper dump (graphite + Cu) < 10 -8 µSv/h • collimators (graphite + Cu) • beam pipe (stainless steel) 0. 08 µSv/h [compared to RFQ: 0. 13 µSv/h ] Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

about graphite chopper dump (detail) Cu Graphite (2 mm) Range 3. 6 Me. V protons in 1. 7 g cm-3 graphite: 0. 135 mm incident protons on chopper dump All protons stopped in graphite (same for the 3 collimators) Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

(p, n) reaction on graphite o 3. 6 Me. V protons o range in graphite: 0. 135 mm o No ENDF/B proton data library for 13 C o (p, n) reaction thresholds: o TENDL is available • • 12 C(p, xn) 19. 6 Me. V 13 C(p, xn) 3. 2 Me. V o graphite: 1. 1% 13 C Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

TENDL p+13 C total and 13 C(p, xn) cross section However, TENDL-2011 Cross Section (barn) 1 E 0 p+13 C total 1 E-1 1 E-2 13 C(p, xn) 1 E-3 1 E-4 TENDL: 1 Me. V steps… 1 E-5 1 E-6 1 E-7 3. 2 Me. V 1 E-8 0 Riccardo Bevilacqua 1 2 3 4 5 6 7 8 Proton Energy (Me. V) 9 10 SATIF-12, April 28 -30, 2014

13 C(p, xn) yield total neutron production yield 1. 0 E-03 1. 0 E-04 1. 0 E-05 our conservative approach MCNPX model TENDL-2011 1. 0 E-06 TENDL-2013 Bair et al 1. 0 E-07 3. 5 4. 5 5. 5 6. 5 Proton incident energy (Me. V) Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

DTL St ain les Stainless Steel 50 µm Cu s. S tee l vacuum drift tube (Cu) Sm 2 Co 17 magnet (50% of cells) scaled densities account for DTL cells structure Cu + 15% cooling H 20

DTL tank length (m) initial energy (Me. V) final energy (Me. V) protons/sec ond 1 7. 62 3. 6 21. 29 5. 4 1012 2 7. 09 21. 29 39. 11 1. 6 1012 3 7. 58 39. 11 56. 81 1. 0 1012 4 7. 85 56. 81 73. 83 7. 7 1011 5 7. 69 73. 83 89. 91 6. 0 1011 Assuming a proton beam loss of 1 W m-1 Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

DTL – integral neutron flux (40 cm wall) 2 3 4 contribution from tank 1 Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

tunnel DTL – dose inside FEB up Prompt dose (µSv/h) 1 E+04 FEB 1 E+03 water cooling 1 E+02 down 1 E+01 neutron dose (up) photon dose (up) 1 E+00 neutron dose (down) 1 E-01 photon dose (down) 0 1 2 3 4 5 6 DTL TANK # Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

dose cell tunnel Prompt dose (µSv/h) DTL – dose in water cooling room 1 E+00 FEB water cooling 1 E-01 neutron 40 cm wall photon 40 cm wall 1 E-02 0 1 2 3 4 5 6 DTL TANK # Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Prompt dose (µSv/h) Total dose in water cooling room INTEGRAL = 3. 7 µSV/h limit 3 µSv/h 1 E+00 RFQ (n+γ) MEBT (n+γ) 1 E-01 neutron 40 cm wall photon 40 cm wall 1 E-02 0 1 2 3 4 5 6 DTL TANK # Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

tunnel DTL – dose in water cooling room Prompt dose (µSv/h) from 40 to 100 cm walls 1 E+00 FEB water cooling 1 E-01 1 E-02 neutron 40 cm wall photon 40 cm wall 1 E-03 neutron 100 cm wall water cooling room: green < 3 µSv/h photon 100 cm wall 1 E-04 0 1 2 3 4 5 6 DTL TANK # Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

FEB – labyrinth (100 m) Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

FEB – labyrinth (100 m) Integral neutron flux from DTL tank 1 Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Prompt dose (µSv/h) DTL – dose in water cooling room 1 E+00 neutron 40 cm wall 1 E-01 photon 40 cm wall 1 E-02 neutron 100 cm wall photon 100 cm wall 1 E-03 neutron labyrinth photon labyrinth 1 E-04 0 1 2 3 4 5 6 DTL TANK # Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

ESS Monolith Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

ESS Monolith 2013 Baseline in TDR [Technical Design Report] o 6 meters radius stainless steel & carbon steel 2014 Question: can we afford 5. 5 meters? Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

ESS Monolith Figure of Merit (given by colleagues of science directorate) o Neutron flux E > 10 Me. V: < 10 -2 n cm-2 s-1 o at 2 meters above proton beam line height above proton beam line: 4 meters Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

mcnpx model by Alan Takibayev (ESS) ESS Monolith o 48 possible beam port positions o 4 beam extraction sectors: • 60 degrees each • 5 degree angular separation Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

80 100 20 120 0 140 340 160 320 180 300 280 260 240 220 200 neutron flux En > 10 Me. V (cm-2 s-1) 40 60 each sector: 50 cm, 20 deg monolith: 5. 5 meters radius + 0. 5 meters concrete (external ring) [unperturbed] slice: 200 – 210 cm above the proton beam line level Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

neutron flux at 220º 20 40 60 80 100 120 0 140 340 160 320 180 300 280 Riccardo Bevilacqua 200 260 240 220 SATIF-12, April 28 -30, 2014

neutron flux at 320º 20 40 60 80 100 120 0 140 340 160 320 180 300 280 Riccardo Bevilacqua 200 260 240 220 SATIF-12, April 28 -30, 2014

neutron flux at 280º 20 40 60 80 100 120 0 140 340 160 320 180 300 280 Riccardo Bevilacqua 200 260 240 220 SATIF-12, April 28 -30, 2014

ESS Monolith: from 6 to 5. 5 o Fo. M given assuming flat response function from neutron scattering instruments o next step: folding neutron spectrum with actual response function This will most likely allow us to go to 5. 5 meters Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Conclusions • flux-to-dose: maximum of ICRP-116 • a nice FEB shielding design • be careful with 13 C(p, xn) • ESS Monolith’s radius maybe reduced to 5. 5 m • download and enjoy mctal 2 root Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

just google “mctal 2 root” o Read mctal files: • all tallies • all mesh tallies o Store the data in a root file • TSparse objects o Fancy plots o All data analysis capabilities of Root o Developed at ESS Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

mctal 2 root http: //code. google. com/p/mc-tools/ Code by Konstantin Batkov & Nicolò Borghi (ESS) SATIF-12, April 28 -30, 2014

Thank you riccardo. bevilacqua@esss. se SATIF-12, April 28 -30, 2014

Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Front End Building (FEB) DTL MEBT RFQ ion source Accelerator Tunnel out of scale Water cooling room Front End Building Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Front End Building (FEB) Water cooling room < 3 µSv/h DTL MEBT RFQ ? ion source Accelerator Tunnel > 1000 µSv/h out of scale i. e. < 6 m. Sv/y [2000 h] Front End Building Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Front End Building (FEB) < 3 µSv/h Water cooling room i. e. < 6 m. Sv/y [2000 h] DTL MEBT RFQ ion source Accelerator Tunnel > 1000 µSv/h out of scale ? Front End Building Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

courtesy of Benjamin Cheymol, ESS MEBT Beam Loss Distributions in collimators Gaussian beam at collimator location, collimator jaw at 3 sigma, particle collimated (1% of full beam) on the all collimator, dimension for one jaw protons per second 1. 70 E+14 Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

courtesy of Benjamin Cheymol, ESS MEBT beam profile Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

TENDL p+13 C total and 13 C(p, xn) cross section TENDL-2013 Cross Section (barn) 1 E 0 1 E-1 p+13 C total 1 E-2 13 C(p, xn) 1 E-3 1 E-4 1 E-5 1 E-6 1 E-7 3. 2 Me. V 1 E-8 0 Riccardo Bevilacqua 1 2 3 4 5 6 7 8 Proton Energy (Me. V) 9 10 SATIF-12, April 28 -30, 2014

Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Integral gamma flux from DTL tank 1 100 cm thick wall Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Integral neutron flux from DTL tank 1 100 cm thick wall Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Water cooling room < 3 µSv/h > 1 m. Sv/h < 25 µSv/h < 1 m. Sv/h FEB Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

incident protons radius (cm) degrees Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

Riccardo Bevilacqua SATIF-12, April 28 -30, 2014

MEBT chopper dump Riccardo Bevilacqua MEBT chopper accelerating cavity DTL SATIF-12, April 28 -30, 2014