September 26, 2020

In Tour, U.S. Nuclear Plant Opens Doors to Make Case

The agency seemed to be seeking to project a balance of confidence and openness to improvements, a challenge now faced by the entire American nuclear industry as the nation watches the Japanese struggle to contain their crisis.

The containment buildings surrounding the three reactors at the Browns Ferry plant here, all of the Mark 1 variety made by General Electric, are almost identical to the ones at the Fukushima Daiichi Nuclear Power Station, which were wrecked by a tsunami on March 11. But the T.V.A. says that the devil is in the details, and that, in many small ways that could be crucial, Browns Ferry is better prepared for the unknown than Fukushima was.

In the decade since the Sept. 11 attacks, the Nuclear Regulatory Commission says, all American reactors have made preparations to limit damages from potential threats like airplanes piloted by terrorists. Some details have been released.

Yet it is clear that from fire hoses to batteries on wheels to components like a strobe light, the three reactors at Browns Ferry have preparations in place that operators say would help in a nightmare situation like Japan’s, a loss of electricity for running its pumps, valves and safety systems. While a tsunami is not an issue in northern Alabama, more than 300 miles from the sea, the loss of all power is always a threat. The plant sits on the banks of the Tennessee River, where floods can reasonably be anticipated, although plant officials say that water levels have never risen high enough to threaten the reactors.

Still, Browns Ferry is ready for “a one-in-a-million-year flood, or however many zeroes you want to go out,” said Preston D. Swafford, the T.V.A.’s chief nuclear officer, who led a group of reporters on a three-hour tour through the plant.

Inside the reactor building, near the entrance to the primary containment structure, are carefully marked spaces with two lime green carts about the size of hand trucks that a supermarket worker might use to roll cases of soda cans to the proper aisle. Each is loaded with batteries.

One cart could power the instruments that measure the water level in the reactor vessel, an ability that Japanese operators lost a few hours after the tsunami hit. Another could operate critical valves that failed early at Fukushima.

“They’re like a backup to the backup,” said Keith J. Polson, the T.V.A.’s vice president for the Browns Ferry site. “That’s what we think the Japanese didn’t have.”

In the best tradition of an industry whose terminology is ever more impenetrable to outsiders, the battery carts are known as E.D.M.G.’s, a label for hardware derived from the industry’s Extensive Damage Mitigation Guidelines, largely put into effect after the Sept. 11 attacks.

Deeper into the building, in an odd-shaped space in the basement between a corner of the square reactor building and the round containment shell is a steam-driven pump. This is something that the designer, General Electric, intended to be available to deliver up to 600 gallons per minute of cooling water into the reactor core even if the electrically driven pumps failed for want of power. An overheating reactor would be likely to have ample supplies of steam to run it.

That worked at Fukushima for a while but appears to have stopped functioning later; the Japanese plant’s operator, the Tokyo Electric Power Company, has not provided an explanation. Again, the T.V.A. suggests that it has backup tools that the Japanese utility, known as Tepco, probably lacked: a battery-powered strobe light stored in a nearby cabinet, and a valve that usually runs on electricity but also has a hand crank.

While the details of the Fukushima catastrophe may be months in reaching plant operators elsewhere, the T.V.A. hypothesizes that Tepco ran out of battery power to control the steam pump. But T.V.A. engineers say they could use the strobe light to determine how fast the pump’s shaft was turning, enabling workers to adjust its speed with a hand-cranked valve nearby.

Article source: http://feeds.nytimes.com/click.phdo?i=8c3e68dd3ad5b69e4288d83ba9e43637

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