SAD

View Full Document Here

Intro
Hazard Summary
- Pretty big table on page 5. Worth a glance
  - Lists general types of hazards, what they could do, how we're controlling for them, how likely they are to happen, and severity/risk
- Definition of Risk on page 9
  - Risk is a function of probability and severity (high severity + low probability = low risk, high + high = high, low + low = low)
LAF Description
1. LAF Subsystems
  - Copper linac through the FEE, FACET-II facility, ESA, LCLS II RGD
  - Copper
    - 2856 MHz, room temp, klystrons, SLED cavities
    - 25 feet under gallery
      - Gallery has klystrons, SLED cavities/modulators, power supplies, cooling water systems
    - 31 sectors (0 in the west, 30 in the east)
      - Each sector ~100 m long
    - Linac West (S0 - 9)
      - decommissioned and removed for superconducting LCLS-II (currently under construction)
    - Linac Middle (S10 - 19) and Linac East (S20 - 30) separated by concrete shielding wall and personnel passageway maze
      - Can be operated independently
      - But share control and water cooling systems
    - People can't be in Linac East if Linac Middle is running
      - prompt radiation risk exposure
    - Max pulse rate is 120 Hz
      - 30 Hz if 120 isn't needed or to reduce power consumption
      - Linac East and Middle can be operated at different rates
        Usually 30 Hz for FACET-II (the usually is suspicious here considering we haven't run it yet)
        Usually 120 Hz for LCLS
    - Linac Middle
      - Max energy of ~16 GeV to FACET-II
      - Positron beam coming in the future when they build a damping ring
      - Not designed to go above 30 Hz
    - Linac East
      - Max energy of ~18 GeV to Undulator Complex (has two undulator systems)
        Generate coherent x-ray beams that can be sent to the NEH and FEH
      - Has previously sent beam to ESA, but that's currently decommissioned
        Could be brought back if needed
  1. LCLS-II Injector
    - Normal conducting laser-driven photocathode gun (186 MHz) followed by a buncher cavity
    - Currently set up to deliver electrons to a Faraday cup for commissioning without additional accelerationThere's currently a concrete shielding wall immediately downstream of the Faraday cup
      - Will be removed before the injector is connected to the superconducting linac
      It's currently a Radiation Generating Device (not an accelerator)
      - Will be reclassified when it's connected to the linac
  2. Linac West
    - LCLS-II injector through Sector 9
    - Currently under construction
  3. FACET-II Injector
    - At Sector 10
    - Produces electrons for acceleration in Linac Middle & delivery to the FACET-II experimental area in S20
    - Normal conducting S-band laser-driven photocathode gun
  4. Linac Middle
    - Middle third of the linac, sectors 10 though 20
    - Designed to accelerate, compress, & focus electron or positron beams to the FACET-II experimental area in S20
    - Magnetic chicane bunch compressors in sectors 10 and 14 shorten the electron beams longitudinally (increasing intensity)
    - Currently unable to produce positron beam
  5. Positron Source
    - Can produce positrons by slamming electrons into a target near S19
      - The target is a plate of high-density, water-cooled tungsten-rhenium
      - It's slowly rotated so that the heat from the beam is dissipated over a higher area
    - Target is followed by RF capture and acceleration sections that make a 200 MeV positron beam
    - You can park all or some portion of the e- beam on (in?) the transport line from S19 to the target
    - We currently can't transport, damp, or reinject positrons in to the linac (all that stuff was decommissioned)
  6. FACET-II Experimental Area
    - In S20
    - Beam transport and focusing system, followed by an area to mount experimental setups, followed by a beam dump
      - The transport and focusing system has diagnostic devices and magnets
        Focuses the beam to a small spot size at the experimental setup
        Compresses the bunches longitudinally for "very" high peak current
  7. LCLS Injector
    - S20
    - Produces electrons for acceleration in Linac East
      - Which drive the LCLS FELs in the Beam Transport Hall
    - Normal-conducting, laser-drive photocathode S-band gun
  8. Linac East
    - LCLS uses last kilometer of linac (S21 through 30)
    - Produces ~2 to 17 GeV
      - Dependent on number and configuration of klystrons
    - Beam lines and shielding could safely transport and dissipate 25 GeV e- beam
    - Magnetic chicane e- bunch compressors in S21 & 24 shorten the e- bunches longitudinally
      - The chicanes divide Linac East into five LCLS areas:
        Linac-1 (L-1)
        Bunch Compressor-1 (BC-1)
        Linac-2 (L-2)
        Bunch Compressor-2 (BC-2)
        Linac-3 (L-3)
  9. Beam Switchyard
    - BSY
    - Provides switching, energy definition, collimation, and transport functions for LCLS and ESA beams
    - Can send compressed e- bunches to either transport line to the BTH on a pulse-by-pulse basis
    - Has beam dumps that can stop and safely dissipate e- beam
  10. A-Line to End Station A (ESA) and Beam Dump East (BDE)
    - ESA is a facility for fixed target experiments
    - A-Line transport system can deflect pulses from the primary beam to ESA on a pulse-by-pulse basis
      - Only a small fraction of them though. Most of them continue to the LCLS HXR undulators
    - Originally designed to handle beam power from the full linac (potentially more than 1 MW), so can safely handle Linac East beam
    - A dump in the Northwest ESA wall can be used with low power beam
    - Currently out of service, but could be easily brought back
  11. The Beam Transport Hall (BTH)
    - Immediately east of the linac BSY
    - Contains two LTU (Linac to Undulator) beam lines
      - e- beam from the linac can be sent to either one
    - Contains two undulator magnet systems
      - HXR (Hard X-Ray) and SXR (Soft X-Ray)
      - horizontal and vertical bending magnets can direct the beam to either
      - Both go to the EBD (Electron Beam Dump)
    - The east end has tune up dumps that provide temporary parking places for the e- beams upstream of the undulator magnets
    - Undulators
      - Series of magnets placed end-to-end along the beam line
      - interleaved with quadrupole magnets, steering corrector magnets, and beam position monitors
      - HXR Undulator
        approximately 32 magnetic segments
        each has a remotely adjustable horizontal gap
        produces a vertically polarized Free Electron Laser (FEL) beam
        selectable photon energies between 1 and 25 keV
      - SXR Undulator
        approximately 20 magnetic segments
        each has a remotely adjustable vertical gap
        produces a horizontally polarized Free Electron Laser (FEL) beam
        selectable photon energies between 0.2 and 8 keV
      - a magnetic chicane and photon filtering system in each undulator system provide self-seeding capabilities
      - Byproducts
        low brightness spontaneous radiation beam
        broader spectral width and divergence
        lower brightness harmonics of main FEL beam
  12. Electron Beam Dump (EBD)
    - After the undulators
    - electrons and x-rays co-propagate to the dump magnets
    - e- beams are deflected down into water-cooled Electron Beam Dumps
      - designed to absorb the full beam power
    - x-rays aren't deflected
      - continue on to the experimental areas through the FEE (Front End Enclosure)
  13. The Front End Enclosure (FEE)
    - first room downstream of the EBD (Electron Beam Dump)
    - beam lines designed to transport photons, not electrons
      - contains mirrors, optical elements, limiting apertures, attenuators, and diagnostic devices for each beam path
        can monitor the position and energy of individual pulses
    - can send photons to two buildings, the NEH (Near Experimental Hall) and FEH (Far Experimental Hall), using mirror systems
      - The FEH hutches (experimental areas) all receive hard x-rays from the HXR undulator line
        CXI, MFX, XCS, and MEC
      - The NEH has a mixed bag of hutches (four in total)
        TMO and 2.x can take soft x-rays from the SXR undulator line
        XPP can take hard x-rays from the HXR undulators
        TXI can take both
      - Each mirror system includes photon collimators to protect the beam line equipment from damage by the photon beam and to intercept bremsstrahlung radiation
    - Sending beam to the FEE requires authorization from both the AOSD (Accelerator Operations and Safety Division) and the LCLS Directorate
    - Safety controls for FEE operation are listed in the undulator complex BAS (Beam Authorization Sheet) and the FEE BLA (Beam Line Authorization)
      - The details and hazard hazard analysis are in the LCLS SAD (Safety Assessment Document)
  14. Technical Support Areas
    - Klystron Test Lab (KTL)
      - Klystrons are tested in Building 44 on test stands
        They undergo routine repair, maintenance and processing
        controlled by KTL standard procedures
      - There's also R&D on RF (Radio Frequency) structures
        Some require ionizing radiation controls approved by both RP (Radiation Protection) and KTL
    - Radioactive Storage and Management Areas
      - Low level radioactive and mixed waste management
      - Radioactive Magnet Storage Yard (B480 and fenced yard including alcove)
        Some legacy radioactive sealed sources and activated materials are stored in the fenced area
      - Radioactive Waste Management Tent (B009)
      - Radioactive Waste Storage Area (B478)
        Low conductivity water resin transfer with subsequent dewatering
    - Beam Dump East Yard
      - contains legacy equipment once used within the A and B Lines
      - also old accelerator components
        dipoles, quadrupoles, sextupoles, experimental test apparatus and fixtures, beamline chambers, and steel shielding blocks
        induced activity of these materials is very low (around background radiation levels at 30cm)
    - Building 24
      - Radiation Calibration Facility (RCF) and Radioanalysis Laboratory (Rad Lab)
      - houses various types of sealed radioactive sources used for instrument calibration
      - supports counting of potentially radioactive samples
    - Misc. Areas
      - Activated accelerator components can be stored, repaired, machined, etc at other locations like:
        Building 24 (RPD laboratories, cable group and other shops)
        Building 25 (MFD light fabrication shop)
        Building 26 (MFD Heavy Fabrication shop)
        Building 30 (MFD storage area)
        Building 31 (MFD vacuum shop)
        Building 33 (Light Assembly)
        Building 44 (Klystron Department)
        Building 84 (Central Laboratory)
        Building 413 (lead storage)
        IR2 (former PEP experimental hall)
        The klystron gallery
2. Accelerator Operations Organization
  - The AOSD (Accelerator Operations and Safety Division) controls LAF (Linear Accelerator Facility) operation
    - Reports to the Associate Laboratory Director (ALD) of the Accelerator Directorate (AD)
    - Charged with day to day running
      - The Normal Conducting Linac and FEL Division (Why not NCLFD? Why are our acronyms so inconsistent...) controls machine development, configuration control, and maintenance
  - The EOIC (Engineering Operator in Charge) is responsible for safe running on a shift-by-shift basis
    - They're assisted in the ACR (Accelerator Control Room) by Accelerator Systems Operators (ASOs)
  1. Operations
    - Controlling Documents
      - CAFO (Conduct of Accelerator Facility Operations)
      - AOSD (Accelerator Operations and Safety Division) Directives
        define the roles and responsibilities of the accelerator operators and specify applicable procedures
      - BASs (Beam Authorization Sheets)
        RGDAS (Radiation Generating Device Authorization Sheet) can be used instead for injector commissioning (i.e. for the LCLS II gun)
        Will be incorporated into a BAS when the linac is being commissioned
    - Engineered safety systems, administrative procedures, and implementation procedures make for safe running
    - EOICs (Engineering Operators in Charge) have primary responsibility for safe operation
    - The ADSO (Accelerator Division Safety Office) provides an oversight function for all accelerator activities
  2. Maintenance
    - Area managers are responsible for managing maintenance activities in close coordination with the AOSD control room staff
      - They collect maintenance requests and schedule the work for the next available maintenance period
    - The ADMO (Accelerator Division Maintenance Office, aka Johnny) coordinates the maintenance schedule
      - ADMO is part of AOSD (Accelerator Operations and Safety Division)
    - The EOIC and area manager can initiate immediate maintenance if necessary
  3. Training
    - Administered by the ES&H (Environmental Safety & Health) division
      - Workers on site (employees, users, contractors) must all take ESHO (Environment, Safety, and Health Orientation)
      - Anyone working in RCAs (Radiologically Controlled Areas) must take GERT (General Employee Radiological Training)
    - Managers and supervisors are responsible for employee training
      - They review employee duties at least once a year to determine what training is necessary and to make sure that the employee has completed it
        Done through the STA (Staff Training Assessment) process at least once yearly
    - Operator Training
      - Training manuals are sets of sign-off sections including:
        ES&H training
        Equipment/accelerator-specific safety training
        search procedures
        PPS (Personnel Protection System) operation
        BCS (Beam Containment System) checks
        use of BASs (Beam Authorization Sheets)
      - Operators complete a separate training qualification workbook for each PPS zone
      - Senior AOSD staff conduct training using the manual checklists
        Checklist items are signed off when the trainee completes the section and demonstrates competence
        AOSD line management has final sign-off after all sections are done and trainers have offered evaluations
      - Records of safety training are summarized in a document called Shift Schedules and Training Record Summaries
        green binder in the ACR, also a digital copy here
        Lists current qualifications for each operator
Hazard Analysis
- Sometimes, things happen that aren't accounted for in the SAD (Safety Assessment Document). The process to review those unreviewed things is called a USI (Unreviewed Safety Issue)
  - Examples: unexpected hazards like beam going where it was never expected to go, or from modifying a PPS (Personnel Protection System) configuration
  - Written DOE approval is required to work with an active USI
1. Hazard Analysis Methodology
  - Safety reviews are conducted during accelerator design/construction and after major modifications (i.e. new features or expanded limits on operating parameters)
    - Starts with hazard identification and ends with controls or alternative mitigation mechanisms
  - Hazard evaluation is a qualitative assessment of its potential severity and the probability of it happening (see Section 2)
2. Environmental Hazards Identification and Analysis
  1. Seismic
    - All accelerator housings (and most SLAC buildings) are designed to withstand a major earthquake
  2. Environmental
    - Site environmental restoration projects are managed by SLAC's Environmental Protection Department
    - Disposal of hazardous waste is managed by the Chemical and Waste Department
    - Radiological environmental protection is managed by the Radiation Protection Department
      - They conduct a yearly assessment of potential airborne radioactive contamination and report it to the EPA (United States Environmental Protection Agency)
        Also estimate resulting potential dose impact to the public (It's never been an issue)
3. Conventional Hazards Identification and Analysis
  1. Chemical
    - SLAC maintains an inventory of hazardous chemicals and copies of manufacturer Safety Data Sheets (SDSs)
    - SLAC industrial hygiene program deals with things like paints, epoxies, solvents, and oils
    - Some electrical contacts use beryllium
      - That equipment is only worked on by people with beryllium hazard training
  2. Cryogenics and Oxygen Deficiency
    - Liquid nitrogen is used for venting vacuum systems during beam line maintenance
    - FACET II and LCLS injector vaults are enclosed spaces with limited airflow that can create an ODH (Oxygen Deficiency Hazard)
      - mitigation: both are equipped with ventilation fans
    - SAD will be revised during LCLS II superconducting linac commissioning
      - we'll end up with a lot of liquid helium
    - Compressed argon, helium, and nitrogen could displace oxygen if released in areas without adequate ventilation
      - mitigation:
        limited volume of gas
        small diameter pipes and tubes for distribution
        relief valves for pressurized containers
        oxygen deficiency monitors (ODMs)
        portable monitors can be used temporarily
  3. Electrical
    - electrical shock and arc flash hazards from mismanaged high voltages, currents, and levels of stored energy
      - mitigation: combination of engineering and administrative controls (i.e. insulation and training/procedures)
      - work is prohibited on energized systems with exposed conductors above 50 volts unless it's proven to be safer than with it de-energized (rarely the case)
    - Anyone working with electrical equipment needs to be qualified
      - necessary training is determined by their manager
    - electrical systems are de-energized for repair/maintenance whenever possible
    - safety interlock systems ensure controlled conditions for access to high voltage/current equipment
    - labels are put new equipment and on old equipment before it's worked on
      - identify hazardous electrical equipment and their sources of power
    - electrical distribution systems undergo preventative maintenance
      - scheduled by F&O (Facilities & Operations Division)
    1. AC Distribution
      - SLAC Master Substation distributes AC power to site substations at 12,470 Volts
        substations step it down to 480 Volts for further distribution
        Access is limited to high-voltage electricians
      - Voltages at or above 480 V pose serious arc flash and electrical hazards
        arc flash can spray molten copper
    2. High Voltage, Direct Current
      - Current can pose both direct and indirect hazards (i.e. falls, bumps)
      - Currents in the tens of milliamps can cause physical injury
        RF and pulsed magnet systems (among others) have potentially lethal power supplies
        mitigation: interlocked access panels, local status indicators, local lockout switches, shorting devices
    3. High Current, Low Voltage
      - electromagnets often operate at hundreds of amps, but relatively low voltages
      - shock hazard can be low, but short circuits can create thermal burn hazards
        mitigation: policies, procedures, warning signs, barriers, interlock systems
  4. Ergonomic Hazards
    - Accelerator maintenance can lead to:
      - restricted spaces
      - awkward/static postures
      - repetitive motions
        particularly from tightening bolts/fasteners around flanged vacuum connections
        mitigation: ratchet-handle tools
      - pressure points
      - vibrating tools
      - forceful exertions
        I.e. from lifting/manipulating large/heavy objects
        if outside job limits or training, work is done by specially trained riggers
    - Accelerator operation has long periods of monitoring displays and manipulating controls that can cause:
      - muscle soreness
      - eye strain
      - repetitive motion injuries
  5. Fire
  6. Ladders
  7. Magnetic Fields
  8. Mechanical
  9. Noise
  10. Noxious Gases
  11. Vacuum and Pressure
4. Radiation and Laser Hazards Identification and Analysis
ASE
QA
Post Ops

Space shortcuts

Child pages

Intro

Hazard Summary

LAF Description

LAF Subsystems

LCLS-II Injector

Linac West

FACET-II Injector

Linac Middle

Positron Source

FACET-II Experimental Area

LCLS Injector

Linac East

Beam Switchyard

A-Line to End Station A (ESA) and Beam Dump East (BDE)

The Beam Transport Hall (BTH)

Electron Beam Dump (EBD)

The Front End Enclosure (FEE)

Technical Support Areas

Accelerator Operations Organization

Operations

Maintenance

Training

Hazard Analysis

Hazard Analysis Methodology

Environmental Hazards Identification and Analysis

Seismic

Environmental

Conventional Hazards Identification and Analysis

Chemical

Cryogenics and Oxygen Deficiency

Electrical

AC Distribution

High Voltage, Direct Current

High Current, Low Voltage

Ergonomic Hazards