Skip to main content

Electrical mishap at high-tech Stanford lab disfigures worker, launches federal probe

The entrance to SLAC National Accelerator Laboratory in Menlo Park on Oct. 19, 2019 | Sundry Photography/Adobe Stock

A high-tech physics lab at Stanford University has been partially closed since federal officials began probing an accident there in late December that left one worker disfigured and hospitalized.

The Dec. 27 electrical explosion happened at the SLAC National Accelerator Lab, which is run under the auspices of the U.S. Department of Energy but is managed and operated by Stanford University. The lab sits on hundreds of acres near campus and employs 1,600 workers specializing in sciences including chemistry, biology and astrophysics.

Other accidents and workplace-safety concerns preceded the lab-wide shut down, a review of internal memos and public records obtained by The Standard found. The December incident recalls another notorious electrical accident in 2004 that led to an electrician suffering serious burns and Department of Energy (DOE) investigators accusing SLAC of routinely overlooking safety violations to keep its particle accelerator operational so it could compete with other labs.

This winter's accident happened as the lab was trying to meet a requirement from the DOE to upgrade an X-ray laser called the Linac Coherent Light Source. Stanford was awarded the $3 billion, five-year contract for operating the project, which is billed as a “world-class discovery machine,” in October.

The investigation into the incident is ongoing and DOE said its findings will be made public.

“After an initial, lab-wide pause, some electrical activities at SLAC remain on hold as the lab continues to gather facts about the incident, which DOE is investigating independent of the lab,” department spokesperson Chad Smith said.

A corridor descends to the beam level at the Linac Coherent Light Source of the Far Experimental Hall in the SLAC National Accelerator Laboratory in Menlo Park. | Sundry Photography/Adobe Stock

The hospitalized electrician, who has not been identified, was struck by a high-voltage electric arc while working as part of a crew shutting down power to the lab, according to a report issued by the DOE's Occurrence Reporting and Processing System.

Coworkers heard the electrical arc, rushed to the scene and called 911 and the lab’s emergency response team.

A DOE notice appears to place some of the blame for the accident on the electrician, saying they were working on the wrong part of the circuit. “In addition, the injured worker was not wearing the required shock hazard and arc flash hazard [personal protective equipment] at the time of the incident," the department wrote in the notice.

The worker’s injury caused the lab to stop all high-voltage work and shut down power to seven buildings for the investigation to proceed, Lab Director Chi-Chang Kao told staff in a letter.

“News of this incident is unsettling and many of you may have questions, but I ask that we all please respect the injured employee's privacy at this time,” Kao wrote. “Our thoughts are with the employee, their family and colleagues, with wishes for a fast and full recovery.”

But there had been several earlier incidents reported.

Two complaints were filed in April with Cal/OSHA, the state agency overseeing workplace health and safety and closed a month later. 

The California Department of Industrial Relations, which enforces the state’s health and safety rules through Cal/OSHA, could not provide detailed information about the complaints because they are confidential.

The DOE spokesperson said the complaints were addressed and the issues were unrelated to the December incident.

Workplace safety incidents increased in frequency and severity early last year and culminated on April 28 with an employee’s significant hand injury while operating machinery. Kao issued a lab-wide “safety stand down,” pausing all work the following week to force staff to assess how to move forward with safety improvements.

“Work will not resume until groups are sure that issues and concerns have been raised and plans to mitigate risks are in place,” Kao wrote in a lab-wide memo on May 2. “Key to preventing future injuries and incidents is recognizing early signs and working swiftly to address them. Everyone's perspective and active participation will be critical as we identify root causes and develop the right solutions.”

SLAC is shown in an aerial digital orthoimage. | Peter Kaminski/United States Geological Survey/Wikimedia Creative Commons

Safety Measures

By September, Kao and interim Chief Operating Officer Marc Clay sent a lab-wide memo praising safety progress but also pointing out other incidents involving the proper use of machinery, maintaining configuration controls of radiation safety systems and managing deviations from work plans.

“These incidents confirm the need to strengthen how we plan, authorize, release and oversee work across the lab,” the memo said.

SLAC implemented new safety measures ranging from automated controls to independent reviews of radiation systems. It also focused on balancing employee workloads and increasing routine training.

“We know that many of the activities underway sit on top of work you’re all doing, which on its own is already complex and challenging,” the memo states. “While in some places priorities and resources have been shifted to accommodate our ongoing efforts, we ask everyone, in particular managers and leaders across the lab, to continue to help prioritize time and focus on these initiatives.”

Kao—who joined the Stanford Synchrotron Radiation Lightsource as an associate lab director in 2012 before taking the helm two years later—initially planned to leave in October. This week, he said his departure would come Friday.

“SLAC’s search for a new lab director is ongoing, and there is no predetermined date for its conclusion,” said Smith, DOE’s spokesperson. “Dr. Stephen Streiffer, who has served as Stanford University’s vice president for SLAC since June, will serve as interim director as the search for a new director continues.”

John Galayda—a former LCLS director who recently retired from Princeton Plasma Physics Lab—said he never felt pressured at SLAC to rush when safety was at stake, and the lab works hard to impress its safety standards on employees and contractors.

“Any project at any time, under any circumstances, is always trying to get the most you can for your dollars in the shortest amount of time—which actually saves money if you do it carefully while remaining safe,” Galayda said. “But when it came to something like control of hazardous energy, I didn’t know anybody who would compromise that.”

A Prestigious History

Founded in 1962, the lab was originally named the Stanford Linear Accelerator Center. There, physicists once smashed atoms in a 2-mile tunnel. Its name changed to the SLAC National Accelerator Center in 2008 and it moved away from particle accelerator science to using extra-bright X-rays to probe the structure of atoms.

Today, it houses the Stanford Synchrotron Radiation Lightsource, which uses X-rays to probe biological samples of ancient texts, and the Linac Coherent Light Source (LCLS), which emits fast pulses of X-rays to take images of single molecules. LCLS has been under a high-stakes but delayed upgrade process since 2016.

“SLAC anticipated achieving 'first light' for its LCLS-II X-ray laser this spring,” Smith said. “The lab will assess the specific impacts on that timetable when a restart plan is in place.”

Editor's Note: An editor's error misattributed the cause of the electrocution in an earlier version of the headline.
Correction: The incident was an arc flash explosion, not an electrocution.

Alex Mullaney can be reached at