1. Normal conduction linac commissioning - update on shielding, radiation monitoring and fire safety
Andreas Jansson, Lali Tchelidze
Riccardo Bevilacqua, Konstantin Batkov, Alan Takibayev
ESHAC meeting, October 1-2, 2018

2. NC Linac Beam Commissioning Steps
NC linac beam commissioning is planned in the following steps:
Ion source and LEBT beam commissioning – currently on-going
RFQ and MEBT beam commissioning (3.6 MeV)
DTL1 beam commissioning (22 MeV)
DTL2 to DTL4 beam commissioning (40 MeV, 57 MeV, 74 MeV)
M. Eshraqi, ESS

3. Ion source and LEBT beam commissioning
Ion source and LEBT beam commissioning – currently on-going applying ESS operational limits and conditions.
Limits:
Personnel is NOT categorised as exposed workers (less than 1 mSv/year).
Beam commissioning shall not exceed proton beam energy of 80 keV.
Systems important to safety:
A safety fence containing 2 mm lead shielding around the entire ion source with a height of 2.5 m.
A Personnel Safety System 0 (PSS0), that controls the access to the area inside the fence (PSS0 controlled area).
Passive environmental dosimeters around the safety fence, for monitoring radiation levels outside the fence.

4. Ion source and LEBT beam commissioning
Administrative controls:
At least one trained shift leader shall be present in the control room when the ion source is running with beam.
Shift leaders shall be trained and qualified on their safety, operational and emergency responsibilities.
Handling, functional check and calibration of any measuring instruments used for radiation monitoring shall be performed according to Chapter 7 of the RP handbook.
8:30 am meetings in Local Control Room with agenda:
summary of the previous day
Shift leader announced and plans of the day discussed and agreed

5. RFQ – DTL4 Beam Commissioning
Shielding is designed and limits are set for:
Beam on FC at the end of RFQ/MEBT – 3.6 MeV
Beam on FC at the end of DTL1 – 22 MeV
Beam on FC at the end of DTL2 – 40 MeV
Beam on FC at the end of DTL3 – 57 MeV
Beam on FC at the end of DTL4 – 74 MeV
Distributed losses – 1 W/m – scaled by the average beam current, for the commissioning stage

6. Reminder - Radiological Hazard Analysis – Summary
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 Stop the proton beam at pre-defined destination
Faraday cup (in MEBT, end of DTL2 and end of DTL4)
MPS
RSF-139 attenuate radiation from beam on FC interaction
FC shielding and TSW
RSF-140 monitor and limit average beam current
BPCS (for monitoring)
MPS (for limiting)
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
REMS & PSS1
H1, H2
AM-10 Limit exposure by applying ALARA approach NA

7. RFQ – DTL4 Beam Commissioning – shielding status
Shielding consists of permanent and movable shielding
Permanent shielding - tunnel concrete structure and berm around
Movable shielding in 6 (six) areas:
1. Front end building (FEB) chicane wall, 2. shielding in FEB side wall penetrations, 3. drop hatch shielding, 4. alignment penetration shielding, 5. stubs shielding, 6. temporary shielding wall.
All of you should be able to see this dashboard via the link

8. Shielding structure with major penetrations
Opening for alignment penetration
Concrete tunnel
Drop hatch
Stubs
FEB
FEB side wall penetrations
FEB chicane
(wall)

9. RFQ – DTL4 Beam Commissioning – shielding status
Movable shielding:
FEB chicane wall – ESS – released
Shielding in FEB side wall penetrations – ESS – in review
Drop hatch shielding – ESS – released
Alignment penetration shielding – ESS – released
Stubs shielding – ESS – not in CHESS yet
Temporary shielding wall – ESS – in review

10. RFQ – DTL4 Beam Commissioning – shielding status
FEB chicane wall – 1 m thick ordinary concrete wall.
1 m thick concrete wall
R. Bevilacqua, ESS

11. RFQ – DTL4 Beam Commissioning – shielding status
Shielding in FEB side wall penetrations – best available filling material will be used as shielding. Additional space is reserved in FEB if measurements show it necessary.
A. Takibayev, ESS

12. RFQ – DTL4 Beam Commissioning – shielding status
Drop hatch shielding – 1 m thick ordinary concrete
Alignment penetration shielding – a combination of concrete/iron as defined in ESS

13. RFQ – DTL4 Beam Commissioning – shielding status
Stubs shielding – shielding filling in the first two stubs is NOT required.
K. Batkov, ESS

14. RFQ – DTL4 Beam Commissioning – shielding status
Temporary shielding wall – 1.5 m ordinary concrete is sufficient to have supervised area outside the wall.
K. Batkov, ESS

15. Radiation Monitoring

16. Fire safety
Radiological consequences during fire in the tunnel is negligible (ESS ), thus we don’t need to mitigate against releases of radioactive material.
Temporary shielding wall will be designed in such a way that a portion of it is movable and an emergency exit will be created when we plan work in the tunnel.

17. Thank you!