On October 2, 1983, an operator closed manual valves on the containment spray pumps at the Turkey Point Unit 4 in Florida, which was standard procedure as the plant prepared for a refueling outage. Unfortunately, Unit 4 was at full power; Unit 3 was entering a refueling outage. The operator had been sent to close the Unit 3 valves but mistakenly closed the Unit 4 valves (the valves look remarkably similar). Had there been an accident on Unit 4, the closed valves would have disabled all of the containment spray pumps. Since these valves could not be opened from the control room, these vital emergency pumps would have been unavailable during the important mitigation stage of an accident.

On February 7, 1984, a technician calibrated the turbine speed instrumentation for the reactor core isolation cooling (RCIC) system at the FitzPatrick nuclear plant near Oswego, New York, following maintenance. Sadly, the maintenance had been performed on the high pressure coolant injection (HPCI) system, not the RCIC system. By calibrating the RCIC turbine speed instrumentation with the HPCI calibration procedure, the technician disabled the RCIC system at a time when the HPCI system was already disabled. A supervisor reviewed the completed procedure and discovered the error. The RCIC turbine speed instrumentation was recalibrated, this time with the proper procedure. Had there been an accident, the disabled HPCI and RCIC systems would have left the plant without its high pressure makeup systems for reactor core cooling. [22]

Nuclear Power's Dirty Little Secret

One June 17, 1970, an operator at the LaCrosse nuclear plant near Genoa, Wisconsin, used a dust cloth to clean the control room. The cloth snagged the identification tag attached to one of the key switches and moved it around to the OFF position. The repositioning of this single switch caused the reactor to automatically shut down.

To prevent this unfortunate event from happening again, the control room operators were instructed to use a feather duster when cleaning. [23]

The training program for operators consists of more than a year's worth of classroom instruction and simulator exercises. The proper techniques for feather-dusting are not covered during this otherwise comprehensive training.

Easy Doesn't Do It

In late May 1990, the Brunswick nuclear plant in North Carolina was shut down because the operators flunked their requalification exams. In early May, fourteen of 20 operators and three of four operating crews had failed the test. On May 19 20, all four crews and eight of 27 operators failed re-tests.

A spokesman for the plant attributed the failures to a change in the retraining program requested by the NRC. According to the spokesman: "The NRC exam is very difficult." [24]

Hopefully, nuclear power plants will only have easy accidents. Hard accidents can be so darned inconvenient.

Aerial Disaster

In January 1971, an Air Force B 52 bomber crashed about 20 seconds short of the Big Rock Point nuclear plant in Michigan. All nine crew members on board the plane died in the crash. The plane had been on a routine training mission. [25] The Air Force (luckily, ours) conducted low altitude simulated bombing runs near the plant for years.

This Picture's Worth A Thousand Cuss Words

On the morning of August 7, 1997, an instructor at the Haddam Neck plant in Connecticut took a picture inside the fire detection panel in the control room. The camera used its flash to light up the darkened interior of the cabinet. An alarm sounded. Three to five seconds later, the fire suppression system discharged Halon into the control room from overhead nozzles. The Halon gas, which functions like carbon dioxide to extinguish fires by displacing oxygen, blew into the control room, scattering papers and dislodging ceiling tiles. A falling ceiling tile struck, but did not seriously injure, an operator on his way out of the room. Within 30 seconds, the control room was abandoned.

After the operators left the control room, they assembled in an adjacent room where they could monitor the control panels through a window. When an alarm light blinked on and off, an operator would rush back into the control room, without self contained breathing apparatus, and respond to it. About 35 minutes later, the ventilation system had removed enough of the Halon gas to allow operators back into the control room.

Subsequent investigation determined that the flash from the camera affected a microprocessor in the initiation circuit for the Halon system. The fire suppression system was supposed to have a one-minute delay between warning alarms and Halon discharge to enable workers to safely exit the area, but the flash caused a premature discharge. It happens. Or so they say.

To prevent future occurrences, the plant's owners posted signs on all fire system control panels warning folks that photography is prohibited inside the cabinets. [26]

It's been said that a picture is worth a thousand words. In this case, the majority of them were probably expletives.

Nuclear-Sized Sink Stopper

On December 28, 1994, a bolt dropped into the Unit 1 spent fuel pool at the Hatch Nuclear Plant in Georgia. An overhead crane was carrying this bolt over the pool when the sling holding the bolt broke. The bolt, 17 feet long by three inches in diameter and weighing 365 pounds, glanced off the side wall and fell to the bottom of the spent fuel pool without hitting the storage racks or irradiated fuel assemblies. The bolt tore a three inch gash in the stainless steel liner. Approximately 2,000 gallons leaked through the hole and through a drain line before workers closed valves in the drain line.

The spent fuel pool water level dropped nearly two inches, causing the fuel pool cooling system pumps to trip. Operators restored the water level after the leakage path was isolated, then returned the fuel pool cooling system to service. Workers removed the bolt and placed a large rubber mat (i.e., a nuclear-sized sink stopper) over the hole to limit leakage until underwater welding repairs were completed.