A Guest Post By: NuclearGrrl
“The musings and opines of a wickedly assertive female nuclear engineer, Buckeye, afro queen, black mamba, feminist, clinic escort, and all around spectacular human being.”
See the original post here: http://nucleargrrl.com/2013/02/06/when-the-lights-go-out/
What did you think of Superbowl XLVII? I thought it was AWESOME – the best Superbowl I’ve watched in years. I was rooting for the San Francisco 49ers – based solely on quarterback cuteness – but alas my team’s comeback was to no avail. Beyoncé’s halftime show was absolutely fabulous. And there was a yawn-inducing power outage at the stadium, which still has all the media guessing, “What happened?”
SMG – the management company that runs the Superdome – has not announced what piece of equipment failed. Entergy and SMG did announce the outage was not caused by an electrical grid interruption. A fault at equipment where the electrical grid ties into the Superdome caused the protection system to trip – that is to open breakers to arrest power supply to the Superdome. Since the Superdome is powered by the CBD underground secondary network,* such operation could be by design. Its purpose would be to protect network reliability, safety and voltage that could be compromised by feedback to the network from the Superdome. What caused the feedback (or if power feedback was actually the cause) remains to be determined.
A football stadium is a technologically exacting work of art. It takes more than seats and concrete to make a great stadium. A designer has to factor in a wide range of features to maximize capacity while providing efficient means for patrons to breathe, drink, use the bathroom, and escape in an emergency. Various events could challenge a stadium’s ability to protect its patrons – fire, earthquakes, terrorist attacks, inclement weather and, yes, power outages.
Power outages can present a danger to patrons. Backup power systems are generally installed to provide emergency power for a stadium if grid power is interrupted or an internal fault causes a local outage. Typically, upon loss of normal power, the alternate source will be on-line within a short period of time: less than one second if provided from a second electrical grid tie-in, around 20 seconds if served by back-up generators.
Nuclear plant electrical systems are designed in much the same way – but on steroids! Operating nuclear plants are required by law to have a second offsite power supply from a different distribution grid source. A nuclear plant’s alternating electrical current system is equipped with protective features that will very quickly switch from the preferred power supply to the second power supply to keep vital equipment energized.
If both those power sources become unavailable – as is what happened at North Anna after last year’s earthquake – a low voltage signal will initiate turbine-generator trip and reactor shutdown. The signal will also start up on-site diesel generators sized to power the emergency equipment necessary to bring the plant to safe shutdown mode and maintain it there for at least 3 days. These generators are each sized to power all necessary emergency equipment. Nuclear plants also have emergency battery banks to power computer systems needed to actuate the emergency diesel generators and some other vital instrumentation and equipment. Back ups to back ups to back ups – that’s Defense in Depth.
So, if the Superdome had been powered like a nuclear plant, could the game have continued uninterrupted thus thwarting the San Fran comeback attempt that kept viewers on the edge of their seats? (Or, well, at least me.) Well, not really. The emergency systems in a nuclear plant, like the emergency power systems in the Superdome, are sized to energize vital equipment only. So, those dim lights just bright enough to reveal Joe Flacco stretching on the sidelines are all we’d get – along with vital ventilation and pumping systems. So no stage lights for the ‘Mercedes-Benz Superdome’ Nuclear Power Station either. Boohoo.
But that’s okay. I needed a break from those chatty announcers anyway.
*I deduced that the Superdome is powered by CBD secondary network. I don’t have the security clearance to verify that.