Safety systems: Protecting researchers, scientists with safety automation
SLAC National Accelerator Laboratory upgraded its relay-based safety system with a new control and safety platform.
They barrel through the 2-mile tunnel and hit a wall at nearly the speed of light. This is no high-tech fender bender. It’s no accident at all. World-class researchers have gleaned life-changing discoveries from these ultra-fast, microscopic collisions for more than half a century.
Top scientists from around the globe apply months, even years in advance for the opportunity to further study life’s smallest particles at the SLAC National Accelerator Laboratory at Stanford University.
The main attraction for most researchers is the opportunity to experiment with the world’s most powerful X-ray laser, created through electrons riding the accelerator’s coveted beam. The remarkable X-ray imaging tool, SLAC’s Linac Coherent Light Source, is a recent addition that has helped transform the facility into a multipurpose lab and the ultimate proving ground for more scientists than ever before (see Figure 1).
Demand is so strong that SLAC is providing 24/7 access to the accelerator beam and is expanding the facility to more than double the number of experiments that can be done simultaneously. Breakthrough discoveries, such as the latest cancer treatments and a better understanding of viruses, fuel cells, and the sun and stars, can be traced back to research done at the SLAC National Accelerator Lab. “The high-powered X-ray laser allows scientists to look at molecules in a way that was not possible—even conceivable—a few years ago,” said Enzo Carrone, deputy director of the lab’s instrumentation and control division and head of the safety systems department.
Ensuring safety, uptime
However, scientific advancements do not come without some challenges. “Our top priority is protecting scientists and staff from potential radiation hazards produced by the accelerator,” said Carrone. “We also must ensure the beam is up and running. Without safety and the beam, little science can be conducted here.”
SLAC has an impeccable safety record, but the expanding and increasingly complex operation required a new level of safety and control. The lab’s original 1940s-era relay-based system did a good job, but it was well beyond its intended service life. “Relays just couldn’t provide the level of intelligent protection and diagnostics support we must have going forward,” Carrone said.
Maintaining laboratory uptime is critical. “The cost of factory downtime is often measured in lost labor and product, but you can’t put a price on the loss of a potential scientific breakthrough,” Carrone said. “That is exactly what’s at stake when researchers can’t finish a project because the accelerator is down. We strive for 98% beam availability, considering the huge impact it can have on science and discovery.”
“The accelerator has been down for hours at a time before, causing lengthy delays in critical experiments,” said Kristina Turner, manager of SLAC’s Personnel Protection System (PPS) upgrade. “We needed a new platform capable of extracting a new level of insight and knowledge from the accelerator system. We had to find an intelligent solution to enable us to better understand our operation and help us greatly reduce downtime by anticipating issues before they occur.”
“These accelerator machines cost hundreds of millions of dollars, and they’re meant to be here for decades to enable important research,” Carrone said. “We must have a control and safety solution that allows us to look 30-plus years into the future with confidence. Our relay-based architecture had run far beyond its course. Our fast-growing lab had to have a flexible and scalable architecture to meet the ever-changing requirements of real-time scientific breakthroughs.”
The home of many life-altering scientific breakthroughs needed a control platform that would enable accelerator operators to manage and monitor the increasingly complex lab and its multiple laser beams and radiation sources. At the same time, SLAC needed a safety platform capable of keeping scientists and SLAC staff out of harm’s way for the foreseeable future. And the laboratory needed its new control and safety system in place within a year.
SLAC gets control, safety upgrade
Following a thorough review of system options with sister labs across the country, Carrone and his team selected control and safety automation solutions from Siemens Industry Inc. The automation used at SLAC is patterned from control platforms at other DOE science labs. “Our collaboration with the Jefferson Laboratory in Virginia, Brookhaven in New York, and others allowed us to select a hardware platform and design a new safety system within our important one-year timeframe,” said Turner. “We had to quickly and effectively implement an intelligent security upgrade capable of handling the complexities of a multipurpose lab. The ability to share ideas with colleagues who had already made similar upgrades made the difference and made it possible to meet our lofty objectives.”
“The safety PLC is the brain behind our new PPS,” Carrone said. Under the hood, the safety PLC uses a Siemens S7-300F safety controller and ET 200S distributed safety I/O to monitor and manage personnel access to and from the accelerator tunnel (see Figure 2). Safety requirements have never been greater, as radiation hazards have increased inside the underground lab with the addition of new beams and adjacent experimental areas.
The high-powered X-ray beam can split into as many as six separate beam lines within the same enclosed area. “We no longer have just one laser source and a couple of beam destinations,” Turner said. “We now have two hazard sources. We’re putting in a third and discussing a fourth beam within that 2-mile tunnel.”
“It’s very important that we make it easy for the accelerator operator to understand what beams are running, given the new layers of complexity we didn’t have a few years ago,” Turner said. Turner and her PPS colleague Matt Cyterski were both accelerator operators before joining the safety systems group.
The new control and safety system enables operators to break through old laboratory silos for a facility-wide view into the accelerator operation. “It would be unthinkable to try to operate and manage our complex accelerator activity without a PLC,” said Cyterski. “This PLC is the primary decision maker that determines when it’s absolutely safe for staff and scientists to move about the experimental areas.”
The safety PLC has the intelligence to enable operators to not only strictly police the restricted areas of the accelerator lab, but also provide them with preventive maintenance alerts. Sensors that enable the PLCs to manage authorized entry through sealed experimental room doors also detect system issues. In the event of a fault, error, or component outage, the control platform can quickly troubleshoot the problem and identify the culprit for engineering and maintenance crews.
“The PLC communicates across a ProfiSAFE network, a backbone for distributed safety I/O and other critical inside information related to the accelerator operation,” said Marv Guggemos, project engineer for EandM. The California-based automation specialist played an integral role in the PPS upgrade at SLAC. “ProfiSAFE is a variation of ProfiNET, which provides deterministic and secure communications via Ethernet.”
The diagnostics capabilities of the PLC and control platform provide peace of mind for accelerator operators and the countless scientists who converge on SLAC to explore countless possibilities using the beam.
“We are already designing and implementing new beams and experimental areas within the accelerator lab,” Turner said. “We had to be absolutely certain that whatever architecture choice we made was the right choice for the next generation of scientists and science.”
As more of the original SLAC National Accelerator Laboratory infrastructure is overhauled, the control and safety teams are eager to build on the momentum they’ve generated with the new automation platform. “The new system has literally helped us pave the way to new and exciting safety and diagnostics applications across our campus,” said Carrone.
Chris Sheehy is an account manager with Siemens Industry Inc. Based in Sacramento Calif., he specializes in machine safety, motion control, machine logic, and visualization applications. Over the past 5 years, he has focused on developing and maintaining Siemens strategic accounts. Sheehy has a Bachelor of Science in Mechanical Engineering from the University of California at Santa Barbara.