At U.S. Nuclear Reactors, Crews Train For The Worst
Filed by KOSU News in US News.
July 6, 2011
Some nuclear industry officials say if Japan had U.S.-style training for its operators, they might have fared better during the multiple meltdowns at the Fukushima Dai-ichi nuclear power plant. In Japan, workers train on generic simulators. Here, every nuclear power plant has an exact mockup of its control room so plant operators can practice more realistic disaster scenarios.
Take for example the Grand Gulf Nuclear Generating Station, south of Vicksburg, Miss., on the Mississippi River.
One recent morning, reactor operators who would normally report to work at the plant instead showed up for work in a building outside the fence, overlooking the plant’s iconic cooling tower. They step into a room that looks exactly like the control room where they spend most of their working days.
“What you’re seeing is a physical replica, down to the books on the shelves and where the trash cans are located, of what the operators will use on a day-to-day basis in the plant,” says Pat Berry, who heads training for Entergy, the plant’s owner.
He’s here today to watch as the plant’s crew is put to the test, with a simulated “bad day at the plant.”
(Simulated) Crises Unfold
Lights start flashing almost immediately.
“We have a CRD malfunction, due to bravo CRD pump trip,” calls out Roger Bond, who’s in charge of the faux control room.
In other words, a pump has failed. And just as the crew checks to be sure a backup pump is working properly, they’re hit with another barrage of alarms.
“Ready for update?” Bond calls out. After a chorus of readies, Bond reports that this simulated plant has now lost a big chunk of its electric power supply. If power can’t be restored quickly, the rules say to shut down the reactor — fast. And now adrenaline starts to flow.
“Attention all personnel, attention all personnel, evacuate containment — evacuate containment,” comes a voice from over the loudspeaker.
As each event unfolds, the crew reacts by the book. Literally. They flip open loose-leaf binders that guide them through the crisis procedures. At this point, it’s time for an emergency shutdown.
“Reactor pressure is about 950 p.s.i.g. and stable,” a worker calls out. “All control rods are full in. Reactor power is zero and stable.”
But just as it seems everything is under control, more alarms ring out.
“Ready for update?” Bond calls out again. “We have a LOCA in the drywell. End of update.” LOCA is a “loss of coolant accident.” In real life, this is very serious — it was the cause of the meltdowns at Fukushima Dai-ichi.
“So essentially they have a hole in the reactor, so they’re losing water out of the reactor,” explains training chief Pat Berry. “So the challenge to the crew now is how to keep the core covered and cooled, even though they’ve got a hole in a pipe, they’ve got the loss of a major part of the electrical power distribution system, and they’re missing that control-rod drive pump we took away from them at the beginning of the scenario.”
They open a series of valves and release billows of make-believe steam into a chamber called the drywell. That relieves pressure in the reactor so they can and pump more water into it. In real life, Berry says, this would ruin the nuclear fuel, but it would prevent a meltdown.
When Training Isn’t Enough
At this point, the instructors stop the scenario so they can critique it. This one went well, Berry says, though every now and then the crew does end up in the midst of a simulated meltdown.
“It can happen,” Berry says. “If the operators take the right actions, we should be able to avoid that, but occasionally we’ll challenge the operating crew to the point where they may find difficulty in doing that.”
Berry says reactor operators in these training scenarios can respond to some pretty intense crises, on the scale even of Fukushima.
But David Lochbaum, a nuclear engineer at a watchdog group called the Union of Concerned Scientists, says he’s skeptical that the mess in Japan could have been prevented, given the real-world conditions there.
“Training would have helped deal with the challenge they had, but when you’re faced with a loss of power for as long as Fukushima went, I think they might have changed the pathway a little bit, but I think the destination would have been largely the same,” Lochbaum says.
He adds that you can’t truly simulate the kind of crisis response we saw at Fukushima, where a lot of the action took place outside the control rooms. Workers scrambled around to try to read dials, fix electrical circuits and struggle with stalled pumps. And he adds training might not be enough when a crew is confronting not only severe conditions but simultaneous crises at multiple reactors.
“Fukushima showed us that we could have an across-the-board situation where all the reactors are in jeopardy and there’s no on-site cavalry that can come running to the aid of the accident unit,” Lochbaum says.
He adds that overall, the U.S. training system is an important element of emergency preparedness. But it’s no guarantee that crews here can handle anything and everything thrown their way. [Copyright 2011 National Public Radio]