Operations Section Leader Radiological Hazard Analysis for Normal Conducting Linac Beam commissioning Lali Tchelidze Operations Section Leader Accelerator Division ESHAC meeting April 11, 2018

Outline Introduction Radiological hazard analysis – prompt and residual radiation Radiological hazard analysis – activated air Radiological hazard analysis – earthquake Radiological hazard analysis – fire in the tunnel Radiological hazard analysis – lightning List of required RSF (radiation safety functions) for NC linac beam commissioning Defense in Depth analysis (ESS operational limits and conditions)

Before I start By the ESS management decision, the AD safety group is now gone All work/support coming from this group is now supposed to come from ESH No resources are foreseen in AD to provide support in conventional safety matters, nor for licensing application (currently I remain as AD representative in licensing team)

Introduction This presentation covers radiological hazard analysis for the normal conducting linac beam commissioning only. Beam commissioning is planned simultaneously with the installation activities in the downstream part of the linac tunnel. Beam commissioning is planned in the following steps: Ion source and LEBT beam commissioning (75 KeV, not covered in this presentation) RFQ and MEBT beam commissioning (3.6 MeV) DTL1 beam commissioning (22 MeV) DTL2 to DTL4 beam commissioning (up to 75 MeV)

Introduction

Radiological hazard analysis – prompt and residual radiation – list of events List of analysed events: EA-13 Planned beam commissioning EA-14 Off-normal beam loss EA-15 Maintenance work in accelerator tunnel EA-16 FC shielding missing

Radiological hazard analysis – prompt and residual radiation – dose rate plots EA-13 Planned beam commissioning Maximal dose rates for 1 W/m beam loss ESS-0136227 K. Batkov

Radiological hazard analysis – prompt and residual radiation – dose rate plots

Radiological hazard analysis – prompt and residual radiation – beam limitations Energy FC Location Average current Average power (W) Beam modes (to be discussed further) 22 DTL4 ws 8.8 µA 194 Probe, Fast, Slow, Fat probe 40 3.0 µA 132 Probe, Slow, Fat probe, Fast(10Hz) 57 1.4 µA 80 Probe, Fat probe, Slow(0.3Hz), Fast (3Hz) 74 1.2 µA 89 DTL2 w/o s 8.8 nA 0.19 Probe(0.2Hz) 3.0 nA 0.13 Probe(0.1Hz)

Radiological hazard analysis – prompt and residual radiation – list of RSF Safety function SSCI2S Event class Functional Group RSF-3 attenuate radiation emitted from proton beam line Structural part of the tunnel and earth berm; all other permanent and movable shielding H1 Operational RSF-138 Ensure to stop the proton beam on FC at predefined destinations Faraday cup (in MEBT, end of DTL2 and end of DTL4) BPCS & MPS-ID RSF-139 attenuate radiation from beam on FC interaction FC shielding and TSW RSF-140 monitor and limit average beam current to values in “Table 3” BPCS RSF-32 Detect elevated prompt dose rates outside accelerator (normal conducting linac) shielding and alert/shut the beam off Dose rate shall be averaged over any one-hour period outside of TSW REMS & PSS1

Radiological hazard analysis – prompt and residual radiation – shielding Permanent shielding structure: Concrete structure (with penetrations) “Movable” shielding structure: FEB chicane wall (ESS-0060233) Shielding in FEB side wall penetrations – not modeled (ESS-0120796) Drop hatch shielding - not modeled (ESS-0120796) Stubs shielding – not modeled yet (ESS-0189229) Alignment penetration shielding – not modeled (ESS-0120796) Temporary shielding walls (ESS-0136227)

Radiological hazard analysis – prompt and residual radiation – shielding Opening for alignment penetration Concrete tunnel Drop hatch Stubs shielding Stubs FEB FEB side wall penetrations FEB chicane (wall) HVAC inlet ducts

Radiological hazard analysis – prompt and residual radiation EA-14 Off-normal beam loss Safety function SSCI2S Event class Functional Group RSF-32 Detect elevated prompt dose rates outside accelerator (normal conducting linac) shielding and alert/shut the beam off REMS & PSS1 H2 Operational

Radiological hazard analysis – prompt and residual radiation EA-15 Maintenance work in accelerator tunnel Residual Radiation (100 days irradiation, 4 hours cooling) Safety function SSCI2S Event class Functional Group AM-10 Limit exposure by applying ALARA approach NA H1 Operational

Radiological hazard analysis – prompt and residual radiation EA-16 FC shielding missing Safety function SSCI2S Event class Functional Group RSF-32 Detect elevated prompt dose rates outside accelerator (normal conducting linac) shielding and alert/shut the beam off REMS & PSS1 H2 Operational

Radiological hazard analysis – activated air Highest expected DAC (derived air concentration) value for planned beam commissioning beam losses is 3.45x10-4 DAC, or 6.9 µSv in 2000 hours. Highest expected DAC values for the 74 MeV beam on Faraday cup is approximately 1.86x10-3 DAC, or 37.2 µSv in 2000 hours. No radiation safety functions are required. ESS-0239196, A. Polato

Earthquake On-going discussions. No agreement, yet, about the worst case scenario.

Fire in the tunnel On-going. Open issues: Worst case scenario Whether or not to credit fire dumpers in safety analysis.

Lightning Planned, but not started.

List of RSF for NC linac beam commissioning Safety function SSCI2S Event class Functional Group RSF-3 Attenuate radiation emitted from proton beam line Structural part of the tunnel and earth berm; All other permanent and movable shielding H1 Operational RSF-138 Ensure to stop the proton beam on FC at predefined destinations Faraday cup (in MEBT, end of DTL2 and end of DTL4) BPSC & MPS-ID RSF-139 attenuate radiation from beam on FC interaction FC shielding and TSW RSF-140 monitor and limit average beam current to values in Table 3 BPCS RSF-32 Detect elevated prompt dose rates outside accelerator (normal conducting linac) shielding and alert/shut the beam off (Dose rate shall be calculated over any one-hour period outside of TSW for H1) REMS & PSS1 H1, H2 AM-10 Limit exposure by applying ALARA approach NA

Thank you!