Fission Stories #101: “Watch This”

July 17, 2012
Dave Lochbaum
Former contributor

On April 19, 1995, operators encountered a problem while restarting the boiling water reactor at the Columbia Generating Station in Washington. The control room operator consulted with the shift supervisor about a problem controlling the water level inside the reactor vessel. The problem was not too little water; instead, the water level was getting too high.

After being shut down for a long time, the boiling water reactor’s vessel was filled with cool water far below the boiling point. As the reactor core’s power level increased, the heat it produced warmed up the water. The water expanded, causing the water level inside the reactor vessel to increase even when no additional water was being supplied.

The plant’s procedures sought to control the water level within 6 inches of its desired level. The operator consulted his supervisor as the rising water level approached the upper end of this control region.

“Watch this,” the supervisor reportedly told the operator.

To lower the water level the supervisor cracked open the valve circled in the figure above, which is within the “reactor water cleanup system,” to allow water to flow from the reactor vessel to the liquid radwaste system. The reactor water cleanup system removes water from the reactor vessel and purifies it before returning it to the reactor vessel. When the reactor is shut down or operating at very low power, the reactor water cleanup system can also be used to discharge reactor water to the main condenser or the liquid radwaste system.

Because the liquid radwaste system’s piping and components were not designed to withstand the high pressure within the reactor vessel, the plant’s procedures did not permit this valve to be opened when the reactor’s power level so high. The supervisor jockeyed the valve until its OPEN light went out and its CLOSED light went on. But the switches for the lights on the valve had been set so that the valve could be up to 4% open and still not cause the OPEN light to turn on.

When the operator and then a second operator reminded the supervisor that procedures did not allow the valve to be opened at this power level, the supervisor maintained that the valve was not open since its OPEN light was off.

The shift supervisor later informed the shift manager about the valve having been opened.

After the next crew of operators arrived and took over control room duties, an oncoming control room operator closed the valve. Really closed. All the way.

The NRC was not pleased with the deliberate violation of operating procedures. Neither was the plant’s owner. The shift supervisor and the shift manager were fired. Really fired. All the way.

Our Takeaway

Nuclear plant workers are drilled time and again that verbatim compliance with procedures is mandatory. This does not mean that they would blindly follow faulty procedures off the cliff. They are also instructed to stop when a procedure glitch is found and formally revise the procedure before proceeding.

But trained and qualified workers following formally reviewed and approved procedures is part of the defense-in-depth approach to safety.

Workers taking shortcuts by deliberately violating procedures and “winging it” is unacceptable, as evidenced by the culprits in this case being fired for their actions and inactions.

“Fission Stories” is a weekly feature by Dave Lochbaum. For more information on nuclear power safety, see the nuclear safety section of UCS’s website and our interactive map, the Nuclear Power Information Tracker.