Oh By the Way – Nuclear Reactor Accidents
Surry 2 Nuclear Power Plant Virginia 12/9/86
“Summary of Incident: Forty seconds after a reactor trip, a main feed water elbow ruptured, releasing steam and water into the turbine building. This water shorted out the security card readers for all the plant and entered a fire protection control panel through an open conduit, shorting several circuits and actuating 62 sprinkler heads. The sprinkler water leaked into the control panels to the Cable Tray Rooms CO2 suppression system and for the Emergency Switchgear Rooms Halon suppression systems, shorting control circuits and actuating the CO2 and Halon systems. The main CO2 supply tank was emptied, CO2 and Halon leaked into the control room, and a worker was momentarily trapped between the C02, the Halon, and an inoperable security door. CO2 generated 2 feet of snow in the cable room.” page A.1-29
Note: “Scram” or “Trip” means a shut down of the reactor.
When the Loma Prieta Earthquake hit, the nuclear industry in the Bay Area had a sudden crisis, an Oh Sh1t crisis! The automatic fire prevention sprinkler systems failed on 80 nuclear sites regulated by Nuclear Regulatory Commission (NRC) causing electrical shorts in the instrumentation because the Nuclear Industry was not waterproof until after the Earthquake.
This article includes some of the 140 accidents from 1980 to 1989 that were reported in “a round about way” instead of the official channels.
“Nuclear Power is Safe” According to the Department of Energy and the Nuclear Regulatory Commission and in order to maintain that safety record accident reports were discouraged especially ones where its snowing in the Cable Room of a Nuclear Power plant!
At Treasure Island the Navy flat out denied that there was any radiation on the island. Northing was buried in the ground and yet they were digging up radioactive materials out of the ground. But the official reports denied it 1994 Baseline Survey Report.
Instead accidents were reported to the U.S. Nuclear Regulatory Commission Advisory Committee on Nuclear Safeguards (ACRS) in correspondence on other topics beginning with the words “Oh by the way, this happened . . .
Ginna New York 11/14/81
Summary of Incident: During a test on satellite station “A”, workers inadvertently activated the control circuits to the water spray solenoid valve actuators, actuating the sprinkler systems in several plant areas. Some water entered the control rod drive switchgear cabinet, causing two control rods to be misaligned to the fully withdrawn position. The water also tripped one Reactor Protection System motor generator set. Operators manually tripped the reactor.
Browns Ferry 1 Athens Alabama 5/3/86
Summary of Incident: An electrical short in the high dry well pressure sensors caused a false high pressure signal to be generated. The cause of the short was moisture in the sensors from an unspecified spurious fire spray actuation eight days earlier. The false high pressure signal actuated several engineered safety features, including all 8 diesel generators, 2 emergency equipment cooling water pumps, and the core spray injection valves. Since the reactor was shutdown, the impact was not serious. However, 30,000 gallons of contaminated water did spill into the lower part of the reactor building.
Vermont Yankee, Vernon, Vermont 8/17/87
Summary of Incident: Offsite power was lost due to a grid interruption. The EDG’s started, followed by 3 pumps. These pumps as well as the diesel pump caused a pressure surge which ruptured a temporary section of 2″ schedule 80 PVC piping. About 2,000 gallons of water spilled on the reactor building refueling floor and seeped into numerous areas, contaminating various local areas in the reactor building. No equipment was damaged.
Peach Bottom 2 Pennsylvania 9/17/82
Summary of Incident: Spurious actuation of a fire suppression valve in the Recombiner Building. Sprinkler water was drained to a floor sump and mixed with radioactive water, causing the sump to overflow. A small quantity of overflowing water escaped the building, contaminating the storm drain system. No equipment was damaged.
Hatch 1 Baxley, Georgia 5/15/85
Summary of Incident: Personnel dragged an overhead crane hook on an instrument water supply vent valve, damaging the valve. The loss of pressure in the pipe actuated the deluge for the control room VAC “A” filter train. The water soaked the “A” charcoal filters and then backed up in the ventilation ducts (because of plugged drains) and sprayed out of a control room vent onto an Analog Transmitter Trip System panel. The water entered the panel and cause the “A” Low-low-set safety relief valve to fail open, caused the EPCI trip solenoid to temporarily energize (rendering BPCI inoperable), and caused the failure of an ATTS power supply. Since the LLS SRV was failed open, the reactor was manually scrammed.
Hatch 1 Baxley, Georgia 6/27/985
Summary of Incident: Worker closes the wrong valve (deluge valve diaphragm chamber water supply valve), inadvertently actuating the deluge over the “IC” startup transformer. The water caused a phase-to-ground fault which tripped the transformer. The trip resulted in a loss of power to the plant “A” and “B” 4160 volt busses. The “A” and “B” reactor recirculation pumps consequently lose their power source, and the plant was scrammed.
Arnold on the Cedar River Iowa 11/23/84
Summary of Incident: A slow leak in a pressurized sensing header surrounding the startup transformer coupled with foreign material clogging the pressure regulator leading to the header caused the deluge system over the startup transformer to actuate. The deluge then caused a short in the startup transformer such that the transformer tripped. This trip resulted in the loss of the non-vital electrical busses, a turbine trip, and a reactor scram.
Hatch 2 Baxley, Georgia 8/28/82 (8/25/82)
Summary of Incident: Following a reactor trip on August 25, 1982, a leaking scram discharge drain valve exposed to full reactor pressure allowed hot water and steam to escape, which eventually emerged in the RCIC room via an uncapped CR1 drain. The steam resulted in a sharp increase in RCIC room temperature, and actuated a deluge system spray head, which sprayed the RCIC instrument rack. The combined high temperature, spray environment led to wetting and corrosion of RCIC instrumentation and switches. Specific switch corrosion was discovered during surveillance testing on August 28, 1982.
Reactor Core Isolation Cooling (RCIC) System
The RCIC system is designed to ensure that sufficient reactor water inventory is maintained in the vessel to permit adequate core cooling. This prevents the reactor fuel from overheating in the event that the reactor is isolated from the secondary plant. https://nrcoe.inl.gov/SysStudy/RCIC.aspx
Vogtle I Georgia 6/3/88
Summary of Incident: Smoke from an electric duct heater actuated smoke detectors. The sprinkler heads did not actuate, but water ran from, the preaction valve leakoff lines into the upper cable spreading room and onto the control room ceiling. Since the control room ceiling was not adequately water tight, water seeped into the control room and entered some process panels. The water in the panels caused the spurious actuation of reactor coolant system equipment. Control room personnel promptly corrected the coolant system configuration.
Braidwood I Illinois 9/23/87
Summary of Incident: Maintenance personnel were reinstalling the handle on a transformer deluge alarm test valve. Since the deluge system had not been isolated before the maintenance work, when the workers inadvertently turned the valve stem, it actuated the deluge system over a unit auxiliary transformer. The deluge actuation then activated the eighty-six lockout relay, electrically isolating both unit auxiliary transformers. This isolation led to a turbine trip and a reactor trip.
River Bend 1 Louisiana 1/7/86
Summary of Incident: A construction worker thought a water curtain solenoid activation switch was a door latch and inadvertently actuated the water curtain. The water ran into two nearby motor control centers, through a floor penetration, and into a load center on the floor below. The water caused a short in the load center, and the short burned up a transformer. The burnt transformer then tripped the breaker feeding that load center and two other load centers. The loss of these three load centers caused a reactor trip.
Callaway I Fulton Missouri 2/22/85
Summary of Incident: Deluge system water leaked into the deluge system hand pull station for the startup transformer. The transformer interlock circuit interpreted this leakage as a deluge actuation and tripped off the startup transformer. Consequently, power was lost to the control rod drive motors and the reactor was manually tripped.
Rancho Seco California 3/19/84
Summary of Incident: Seal oil system problems required manual operator intervention. Inadequate tank level control allowed hydrogen to escape from the main generator, resulting in an explosion and fire. The CO2 system actuated to extinguish the fire, the turbine was manually tripped, and the reactor tripped.
Arnold on the Cedar River Iowa 11/4/84
Summary of Incident: The main auxiliary transformer exploded and burned, resulting in loss of power to non-essential busses, a main turbine trip, reactor scram, and damage to and tripping of the adjacent startup transformer. Deluge systems for both transformers initiated. HPCI and RCIC were started to recover reactor coolant level.
High Pressure Coolant Injection (HPCI) System The HPCI system is a single-train system that provides a reliable source of high-pressure coolant for cases where there is a loss of normal core coolant inventory. The HPCI system is actuated by either a low reactor water level or a high drywell pressure.
North Anna 2 Louisa, VA 7/3/81
Summary of Incident: An internal fault in the “B” phase main transformer ruptured the side of the transformer. The resulting oil spray and fire exceeded the capability of the A and B phase deluge systems and required extensive firefighting efforts. The event caused a reactor scram, loss of the 2J emergency bus, spurious ECCS actuation, and other complications.
There are more.