LSO Workshop: LCA engineered search controls for the LCLS User Facility at SLAC

Two reportable incidents, one in December 2021 and one in February 2024, occurred when a User Facility LCA was transitioned to Class 4 laser operation while a worker was present without laser protective eyewear (LPE). In both cases, the workers without LPE were discovered within ~10 minutes and there was no hazardous exposure. The incidents led to a DOE non-compliance tracking system finding and one of the corrective actions is to implement engineered search controls for the LCLS User Facility LCAs, to ensure a search is completed before a Class 4 operation mode can be set.

This presentation describes the search controls being implemented, which include:

1. Press-to-activate search buttons that require the searcher to go to all accessible areas of the LCA.
2. If an access door opens during the search, the search is invalidated. The search is also invalidated if the search doesn’t complete within 3 minutes, or if the ‘search cancel’ button is pushed at the control panel.
3. Audio warning messages that indicate:
   • the search is in progress;
   • the search completed; and
   • the LCA transitioned to a Class 4 operation mode.
4. LCA electronic sign displays that indicate:
   • “Search in Progress” alternating with “Laser Workers Only” while a search is in progress; and
   • “Class 4 Laser Imminent” alternating with “Carry Goggles”, if the search is completed, but the LCA is not yet transitioned to a Class 4 operation mode.

Michael Woods, CLSO, is the Laser Safety Officer at SLAC National Accelerator Laboratory. He is an Engineering Physicist, with a B.Sc. in Engineering Physics from Queen’s University in Kingston, Ontario, Canada and a Ph.D. in High Energy Physics from the University of Chicago. He spent 20 years as a researcher in experimental particle physics and accelerator physics, utilizing high power laser systems for photo-injectors, Compton polarimeters and electron beam diagnostics. He became SLAC LSO in 2008. He is a member of the ANSI Z136 SDC, ADCOM, SSC-1, SSC-8 and TSC-5 committees and is Chair of TSC-4 for Control Measures, Training and Laser Safety Programs.