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LCLS Shielding Design. Radiation Safety and Accelerator Design and Operation at SLAC. Design Determine hazards: prompt radiation, residual radiation, air and soil activation/contamination, etc. Define design objectives, list operating modes Determine beam losses and perform ray trace studies
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Radiation Safety and Accelerator Design and Operation at SLAC • Design • Determine hazards: prompt radiation, residual radiation, air and soil activation/contamination, etc. • Define design objectives, list operating modes • Determine beam losses and perform ray trace studies • Review • RP Peer Review • RSO and/or RSC review • Readiness review • Implementation • Installation, testing, calibration, verification of implementation, training operators, posting, develop configuration control program
(Radiation Safety … at SLAC (cont.) • Authorize • RSO Approval, PM authorization • Operation authorization (BAS, BLA, SDR/IRI/RSS, PPS and BCS procedures • Operation • Commissioning plan, inspections, monitoring • Performance Review • Review area doses, prompt survey, induced activity • Report doses to workers and public • Indentify and implement improvements
Implementation of Design Process for LCLS • LCLS Project Documentation • RP LCLS Related Documentation • Design Beam Parameters • Shielding Design Criteria • Modeling and Benchmarking • LCLS Accelerator Housing Shielding Design Features
LCLS Project Documentation • List of Related LCLS Documents • PMD 1.1-016-r0, Linac Coherent Light Source Preliminary Safety Analysis Document • GRD 1.1-001-r0, Linac Coherent Light Source Global Project Requirements • PRD 1.1-011-r1, Electron Beam Loss in the LCLS • PRD 1.9-001-r1, Physics Requirements for LCLS Conventional Facilities • ESD 1.1-310-r3, LCLS Personnel Protection System Requirements • ESD 1.1-311-r0, LCLS Beam Containment System Requirements • ESD 1.1-312, LCLS Machine Protection System Requirements • ESD 1.2-151, Changes to the Radiation Shielding in the LCLS Injector Wall Area • PSAD --- 100 mrem/yr non-rad worker, 1 rem/yr rad worker, 3 rem max credible beam event, dose to max exposed public from LCLS must be “a small fraction of” 10 mrem/yr … • GRD --- max operational beam power 5 kW, … • PRDs --- max credible beam, max continuous loss, … • ESDs --- detailed engineering specs
RP Related Documentation • List of LCLS Related Documents from RP • Elements of Radiation Safety for Accelerator Design & Operation at SLAC • RP-04-09, Radiation Safety Scheme to Protect People to Work in the LCLS-Injector Vault during LINAC and PEP-II Operation • RP-05-16, Penetration Issues in LCLS Injector Area during LINAC/PEP-II Operation • RP-05-02, Streaming calculations through LCLS injector penetrations using MARS14 Monte Carlo code and comparison with analytical methods • RP-05-15, Shielding and BCS Requirements for Phase One of LCLS Injector Operation • RP-05-07, MARS15 Simulation for the LCLS Dump Line • RP-05-08, Residual Activity Simulation for the LCLS Beam Dump by Mars15 • RP-06-03, Shielding Design Study for the LCLS Beam Dump Line • RP-05-14, Shielding Requirements for LCLS Front End Enclosure, White Beam Optics Room and Near Hall Hutches • RP-06-XX draft, FLUKA Calculations for LCLS Mazes and Penetrations
Beam Parameters • Max values for purpose of shielding design * Design beam max is 1.6 kW, shielding is designed for 5 kW
Shielding Design Criteria • Normal mode of operation • The integrated dose equivalent outside the BTH must not exceed 0.01 Sv/yr (1 rem/yr) • The integrated dose equivalent to personnel working inside and around the experimental hutch shielding barriers should not exceed 1 mSv/yr (100 mrem/yr) • Maximum Credible Beam • The dose equivalent-rate is limited to less than 0.25 Sv/h (25 rem/h), and integrated dose equivalent of less than 0.03 Sv (3 rem)
Modeling and Benchmarking • MARS15 Simulation of LCLS Dumpline 14.1 GeV electrons Bending into the beam dump Secondary particle shower By beam loss at first bending magnet
Beam Dump Hall Modeling • Prompt dose Vertical distributions of prompt dose rate for beam loss at first bending magnet entrance at 1 mrad (14.1 GeV-30W)
Beam Dump Hall Modeling (cont.) • Residual activity Below 0.01 mSv/h at top concrete Residual Dose Rate (30-day operation 1-day cooling)
FFTB LCLS Accelerator Housing Shielding Design Features • BTH walls, ceilings, entrance mazes, and penetrations are design to meet RP specifications. • LCLS (5 kW, 15 GeV) walls much thicker than FFTB (2.4 kW, 50 GeV) 4+ ft 6 ft Ground Level
BTH - Support Buildings • 6 ft ceiling for occupied areas • Note penetration design for cables
Beam Dump Hall Plan View Entry Maze Covered trenches Electron beam descending to pit
Beam Dump Hall Elevation View Muon steel • Elevation view Dump Pit Lid (Steel) xrays electrons trench Dump Pit
Beam Dump Coverage • Example section taken through center of beam dump • Result after many iterations between architect, structural engineer and RP Parking
Beam Dump Steel Shielding • Very heavily shielded • ≈ 400 tons steel, not including overage or FEE/NEH wall. • Mixture of existing weakly radioactive and newly purchased steel. SLAC to provide all steel. • Installed while Beam Dump Hall is open • Beam dump is in the cut and cover section • Removable parts of the lids allow access to pit • Requires downtime
LCLS Shielding Design Summary • SLAC radiation safety and accelerator design process has been implemented for LCLS • Design criteria is well established • Most modeling and analysis is done • Construction design incorporates shielding required to meet the design criteria.