EURISOL DS Task meeting Orsay, 07 Janvier Preliminary shielding assessment of EURISOL Post Accelerator D. Ene, D. Ridikas. B. Rapp

EURISOL DS Task meeting Orsay, 07 Janvier Tunnel shielding configuration –Thicknesses of shield blocks –Beam dump designs & shields Induced radioactivity & dose rates for planning interventions inside the tunnel Radiation environment characterisation – Production of contaminants – Source term for airborn transportation Goals:

EURISOL DS Task meeting Orsay, 07 Janvier Experimental areas and beam dump 1 LINAC Without stripper MeV/u 150 MeV/u 209 m 44 m /m Nb + (Fe or Al) + Cu + He Exit MeV/u Experimental area and beam dump 21.3 MeV/u Schematic view of the two options for the EURISOL LINAC -variant# 1&2 With stripper Foil : C 3 mg/cm² Cu + Fe + slits (2mm W, 1cm Cu) Experimental areas and beam dump LINAC 10 m Stripper MeV/u150 MeV/u 21.3 MeV/u /m 60 % in the first 5 m Nb+(Fe or Al)+Cu+He Exit MeV/u Experimental area and Beam dump Nb+(Fe or Al)+Cu+He 44 m m Energy gradient for 132 Sn 25+ Variant #2 Energy gradient for 132 Sn 25+ Variant #1

EURISOL DS Task meeting Orsay, 07 Janvier Shielding design requirements H*(10) [  Sv h -1 ] Total_H*(10) [mSv y -1 ] Public areas0.11 Controlled areas1020 / 2000 h Accident beam loss: Total_H*(10) ≤ 10  Sv

EURISOL DS Task meeting Orsay, 07 Janvier Calculation model 132 Sn  Results obtained for z=3m, opening   (18 o – 53 o )

EURISOL DS Task meeting Orsay, 07 Janvier PROMPT RADIATION: assumptions & approach* A shield designed for a continous beam loss of m -1 during the routine operation is also adequate for an accident loss of the full beam at a localised point, providing that the linac cutoff time is less than 1s. * S. Agosteo, M. Silari, CERN Note 088/ TIS-RP/TM/ ** A. Fasso, K. Göebel et all Shielding against high energy radiation, Nuclear and Particle Physics, Vol 11, (1990) A full beam loss at a localised point must not give rise to a D.E.R. > 100 mSv/h outside the shielding and the beam has to be swithed off within a time short enough that the D.E. from this accident condition remains negligible. Continuous loss Accidental loss

EURISOL DS Task meeting Orsay, 07 Janvier PROMPT RADIATION: method for bulk shielding calculation A shield designed for a continous beam loss of m -1 during the routine operation is also adequate for an accident loss of the full beam at a localised point, providing that the linac cutoff time is less than 1s. Continuous loss Accidental loss

EURISOL DS Task meeting Orsay, 07 Janvier E [MeV/u]   [Sv m -2 ion -2]  [g cm -2] H  [Sv m -2 ion -2]  [g cm -2 ] E E E E E E E E E PROMPT RADIATION: Neutron attenuation curves in concrete 21MeV/u150MeV/u

EURISOL DS Task meeting Orsay, 07 Janvier PROMPT RADIATION: EURISOL shielding - detailed strategy Variant# 1: no stripper Variant# 2: with stripper Uncontrolled beam loss of m -1

EURISOL DS Task meeting Orsay, 07 Janvier PROMPT RADIATION: Schematic diagram of EURISOL shielding (1) Staff Energy [MeV] Length [m] Thickness (cm) V staff (m 3 ) *  for a tunnel surface of 3 m x 4 m PublicThickness (cm) V public (m 3 ) *  for a tunnel surface of 3 m x 4 m RFQ SIL(1) SIL(2 ) Experiment rooms MeV/u 21.3 MeV/u 150 MeV/u Experiment rooms 44 m 165 m 2.8 W m -1 => 19.8 W15 W10 W6 W beam dump Uncontrolled beam loss of m -1 * Correspond to a width = 1m staff public Dump / 2.8kW | 165 | 230 Dump / 19.8kW | 385 | 500

EURISOL DS Task meeting Orsay, 07 Janvier PROMPT RADIATION: Schematic diagram of EURISOL shielding (2) Energy [MeV]21.3 Stripp er Length (m) Staff Thickness (cm) V staff (m 3 ) *  for a tunnel surface of 3 m x 4 m Public Thickness (cm) V public (m 3 )  for a tunnel surface of 3 m x 4 m RFQ MeV/u SIL(1) SIL(2 ) Experiment rooms 21.3 MeV/u 150 MeV/u Experiment rooms 44 m 102 m 2.8 W m -1 => 7.92 W 6 W4 W2.4 W beam dump Stripper 1.68 kW Uncontrolled beam loss of m -1

EURISOL DS Task meeting Orsay, 07 Janvier PROMPT RADIATION COMPARISON: EURISOL shielding #1  #2 Variant# 1 Length (m) Thickness (cm) StaffPublic V * (m 3 )= Variant# 2 Length (m) Thickness (cm) StaffPublic V * (m 3 )= * Correspond to width = 1m beam dump RFQ beam dump Experiment rooms Experiment rooms RFQ SIL(1) SIL(2 ) MeV/u 21.3 MeV/u150 MeV/u 44 m102 m 2.8 W m -1 => 7.92 W m -1 => Stripper 10 m 1.68 kW Uncontrolled beam loss of m -1 SIL(1) SIL(2 ) Experiment rooms MeV/u 21.3 MeV/u150 MeV/u Experiment rooms 44 m165 m m -1 => 1.98 W m -1 => 0.28 W

EURISOL DS Task meeting Orsay, 07 Janvier RESIDUAL RADIATION: Method Neutron flux in i th cell ⇨ The neutron flux is assumed to be constant over the irradiation period and not being modified by the irradiated medium Geometry and materials description DCHAIN- SP-2001 PHITS Residues in i th cell Irradiation Scheme- 12 days -irradiation H*(10) MCNPX Activation products & Photon sources

EURISOL DS Task meeting Orsay, 07 Janvier Residual RADIATION: Activation of copper Energy dependence from 21 to 150 MeV/uMajor radio-nuclides at 150 MeV/u

EURISOL DS Task meeting Orsay, 07 Janvier Residual RADIATION:H*(10)* from irradiated copper target * ANSI/ANS Photon Flux to DER CF

EURISOL DS Task meeting Orsay, 07 Janvier Residual RADIATION: Induced radioactivity in concrete walls Energy dependence from 21 to 150 MeV/u Residual activity as a function of wall thickness

EURISOL DS Task meeting Orsay, 07 Janvier Residual RADIATION: Induced radioactivity/H*(10) in concrete walls H*(10)_contact  2  Sv/h for 1h cooling time H*(10)_at 1m = 0.4  Sv/h for 1h cooling time

EURISOL DS Task meeting Orsay, 07 Janvier Residual RADIATION: Induced radioactivity in air

EURISOL DS Task meeting Orsay, 07 Janvier Residual RADIATION: 132 Sn Implantation in SIL structure Total activity due to implantationTotal dose rate due to implantation

EURISOL DS Task meeting Orsay, 07 Janvier Residual RADIATION: Activity / H*(10) inside the tunnel 21MeV/u 150MeV/u

EURISOL DS Task meeting Orsay, 07 Janvier  Analysis of the possibilities to reduce the shield thicknesses in compliance with ALARA principle has to be done The proposed thicknesses of the shielding guarantee an integrated dose bellow the acceptable limit with sufficient margin both at normal operation and accidental situations assuming that the beam cut off 1 s is feasible From the shielding safety point of view, SIL#2 is more advantageous variant since it requires nearly 2 times less of the shielding compared to SIL#1 Placing the LINAC in a designated controlled area (dose below 10 mSv h-1) might reduce the total shielding by another factor of 2 Prompt radiation of other ion species might have an important impact on the shielding. Calculations shown that in case of 6 He 2+ acceleration at 250 MeV/u, the concrete block shielding thickness should be increased significantly compared to the reference case ( 132 Sn at 150MeV/u) Conclusions (1)

EURISOL DS Task meeting Orsay, 07 Janvier Residual activation field inside the tunnel are arising mainly from copper structure activation in the high energy zone of the accelerator, while in the accelerator low energy zone the ion implantation is the most significant contributor The total residual activity of ~6*10 6 Bq g- 1 coming from accelerator structure at 1 hour decay time is due to 64,62,61,65 Cu radio-nuclides, while at long times 59 Fe, 60 Co and 63 Ni dominate Consequently to the conservative assumption accounted high radioactivity value of more than Bq originating from 132 Sn implantation was found. Accumulation of the daughter 132 I nuclide starting with 1 hour decay period increases considerably the potential hazard inside the tunnel Contribution of the tunnel concrete walls to the total activity and consequently to the H*(10) is not significant 41 Ar and 11 C are the main short lived radio-nuclides produced in the air contribute up to 0.35Bq cm -3 at the operation shut-down time. While for longer decay times 7 Be is dominant. Specific activity of 41 Ar overtakes the radionuclide discharge limit with almost one order of magnitude  Effect of the accumulated activation has to be studied by analysing various irradiation scenarios  Results obtained for the high energy accelerator zone should be revised choosing a more realistic approximation for the ion implantation in the structure Conclusions (2)

EURISOL DS Task meeting Orsay, 07 Janvier  Maintenance operations inside the tunnel have to be planned In the high energy zone of the LINAC continuous accessibility inside the tunnel in the beam-off stage is possible only after one week cooling time  However, if the intervention is required earlier, an occupancy factor of minimum 570 hours/year allows meeting the constraint of 20 mSv y -1 ; Contact dose rate values significantly higher than the limits show that a remote handling for the dismantling of certain components is necessary. E.g. the accelerator structure in the high energy zone even after one month cooling time would contribute to the contact dose higher than 1 mSv h -1. Definition of the intervention procedure is required. To protect the personnel during the handling operations the access and transportation paths should be set-up and a hot cell might be necessary to be included in the facility lay-out.  The air activation results show that a ventilation system in the tunnel might be necessary  Several equipments and material should to be disposed of as radioactive wastes. Conclusions (3)

EURISOL DS Task meeting Orsay, 07 Janvier Follow-up works:  Refined results based on more realistic implantation model at higher energies  Beam dumps design and associated shields  Sizing of the shield and management of the access to the controlled areas inside experimental halls  Estimates of the contaminant production in the soil and the source term for the airborne transportation necessary for environment impact assessment Planning

EURISOL DS Task meeting Orsay, 07 Janvier Necessary detailed characteristics of the Physics Target Areas inside the Experimental Hall has to be specified in terms of:  Number of rooms and their dimensions  Beam energy and current  Physics Target materials and geometries  Typical duration of the physics experiment 2. Information on ion implantation mechanism available (?) inside the EURISOL DS comunity Requirements

EURISOL DS Task meeting Orsay, 07 Janvier PROMPT RADIATION: Other ion species