Oconee (USA)

Map of Oconee

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3 * 860 MW PWR units constructed by B&W grid connection in 1973/74

Facilities in Oconee

plantreactor typconstruction startoperation startshut down
Oconee-1PWR19671973
Oconee-2PWR19671973
Oconee-3PWR19671974
1998-07-07
Duke had-delivered to NRC a four-volume, 1,000-page application to add 20 years to the operating license for the three-unit Babcock & Wilcox plant. The application reflects five years of research and preparation,

To prepare the application, Duke spent approximately $8-million. They expect to spend roughly an equal amount just for the NRC application review.
The price for license renewal does not include equipment upgrades or refurbishment.
Duke will replace the SGs at Oconee if the licenses are renewed and probably won't, if they are not. The three B&W PWRs went into commercial operation in 1973 and 1974.

1997-04-23

Duke Power Co. plans to restart Oconcee-2 and -3 later this month with NRC approval after modifying the units, following problems with their high pressure injection (HPI) systems.
Duke took down Oconcee-2 April 23 because of a reactor coolant system leak from a cracked HPI nozzle weld. While taking unit 3 down to check whether it had a potential for the same leak, Duke had trouble with the HPI pumps.
The leak on the piping around one of unit 2´s reactor coolant pumps was caused by a cracked weld Duke missed when inspecting the piping last year.
The crack occurred in a transition piece between the HPI line and reactor coolant loop nozzle. Thermal stresses led to the crack due to a gap between the safe-end and the rolled area of the nozzle thermal sleeve. Thermal stress caused similar safe-end cracking in Babcock & Wilcox plants in the 1980s, prompting plant owners to develop a program using radiography to identify gap development.
However, the HPI pumps' failure on unit 3 pointed up a problem that may exist at all three units. The pumps failed because letdown storage tank indications were wrong, Duke said. The tank supplies water to the HPI pumps. A leaking fitting, combined with instrumentation sharing a common pipe, or reference leg, caused the inaccurate indications, the company said. Duke has added some additional monitors on unit 2, plants to add some to unit 3, and also will look at unit 1´s letdown storage tank.

1996-09-25

Shutdown after an non-nuclear steam accident that injured seven employees.

1994-01-11

During refueling 8 plugs of SG tubes have been found at the RPV bottom. 14 plugs have come loose. The failure was caused during plugging in 1992,

1992-10-19

Plant trip and loss of offsite power with complications: both Keowee units were unable to automatically supply emergency power due to unexpected system interaction. At Oconee backup emerg. power is supplied by two hydroelectric units instead of the usual EDGs.

1992-08-19

breaker coordination poblem affecting both KEOWEE hydro units could render both emerg. power path inoperable. if the output circuit breakers for both hydro units close simultaneously and out of phase, the hydro units could be damaged. Cond. existed since initial operation.

1992-08-19

Breaker coordination poblem affecting both KEOWEE hydro units could render both emerg. power path inoperable. If the output circuit breakers for both hydro units close simultaneously and out of phase, the hydro units could be damaged. Cond. existed since initial operation.

1992-08-19

Breaker coordination poblem affecting both KEOWEE hydro units could render both emerg. power path inoperable. If the output circuit breakers for both hydro units close simultaneously and out of phase, the hydro units could be damaged. Cond. existed since initial operation.

1991-11-23

Unisolable leak in a pressure monitoring line (10 mm diameter) at the top of SG caused an accident:
190.000 liters of primary coolant steamed into the containment before the reactor could be brought to shutdown. Leak rate was 340 liters per minute.

1991-09-20

During outage misalignment of valves caused overpressurization of part of the units LPI system and the diversion of 45.000 liters of primary coolant to a storage tank in the auxiliary building. The misalignment caused pressure in the LPI system to rise above 1,4 MPa. A suction relief valve opened, dumping the overpressured water to the tank. The RCS lost 46.000 of the 300.000 liters, but the water level in RPV remained constant, because the void in the PRZ increased and compensated the loss of water.

1991-09-18

All 3 HPCI pumps were declared inoperable when it was discovered that the operating limit curve for the letdown storage tank would permit operation that could result in gas bounding of the pumps

1991-09-07

During refueling outage a mis-aligned valve in the service water system caused primary coolant to rise steadily over 4 hours from 45° to 90 °C - without anyone noticing. The temperature rise was not detected before workers in the reactor building noticed vapor coming up of the water covering the open reactor vessel. the core was never close to being uncovered, fuel was not damaged.

1991-07-03

because of a design error (unanticipated systems interaction), the low MFW pump discharge pressure signal may not actuate the required systems: EFW, RPS loss of feedwater trip, ATWS mitigation safety actuation, cond. existed since the late 1970's / early 1980's.

1991-07-03

Because of a design error (unanticipated systems interaction), the low MFW pump discharge pressure signal may not actuate the required systems: EFW, RPS loss of feedwater trip, ATWS mitigation safety actuation, Cond. existed since the late 1970's / early 1980's.

1991-07-03

Because of a design error (unanticipated systems interaction), the low MFW pump discharge pressure signal may not actuate the required systems: EFW, RPS loss of feedwater trip, ATWS mitigation safety actuation. Cond. existed since the late 1970's / early 1980's.

1991-05-29

breaker coordination problems between motor control centers could result in the loss of power to safety related systems, cond. existed since initial operation

1991-04-12

Error in the coordination logic of the circuit breakers protecting safety related auxiliary loads at the Keowee hydro station rendered both Keowee stations inoperable. Condition existed since the late 1960's.

1991-04-12

Error in the coordination logic of the circuit breakers protecting safety related auxiliary loads at the Keowee hydro station rendered both Keowee stations inoperable. Condition existed since the late 1960's.

1991-03-08

Shutdown cooling (during refueling outage) was lost: A containment sump suction valve was exercised without a flange in place, resulting in draining of the line whose source was the RCS hot leg into the sump. 50.000 liters of water drained from the RPV to the sump. Dropping the water level in RPV 2,5 m. At its lowest level there was still 1 m or 32.000 liters covering the fuel. Vessel was refilled from borated water storage tank. Operators shut off the RHR pump to prevent it from being damaged.

1991-01-08

Design error in the emerg. power system could result in a loss of both trains due to a single failure.

1990-11-19

system configuration requirements during operation below 60% power may not ensure adequate flow of HPCI to he vessel during a LOCA, condition existed for an indeterminate period of time.

1990-11-19

System configuration requirements during operation below 60% power may not ensure adequate flow of HPCI to the vessel during a LOCA. Condition existed for an indeterminate period of time.

1990-11-19

System configuration requirements during operation below 60% power may not ensure adequate flow of HPCI to the vessel during a LOCA. Condition existed for an indeterminate period of time.

1990-07-31

design error existed since 1973 regarding the Koewee emergency power system; design failures might prevent the system from providing adequate powerduring a LOCA.

1990-07-31

Design error existed since 1973 regarding the emergency power system; design failures might prevent the system from providing adequate power during a LOCA.

1990-07-31

Design error existed since 1973 regarding the Koewee emergency power system. Design failures might prevent the system from providing adequate power during a LOCA.

1990-04-24

design deficiencies discovered in electrical power system.: inadequate undervoltage protection and single failure vulnerability, could have resulted in the degradation of engineered safeguards equipment

1990-04-24

Design deficiencies discovered in electrical power system: inadequate undervoltage protection and single failure vulnerability, could have resulted in the degradation of engineered safeguards equipment.

1990-04-24

Design deficiencies discovered in electrical power system.: inadequate undervoltage protection and single failure vulnerability, could have resulted in the degradation of engineered safeguards equipment.

1989-09-21

Leaking seal weld in PRZ heater bundle; The leak is half -inch long + a couple of pinholes - resulted in steam wisping from the weld. caused by heat-stress during the units 15 -year operation

1989-03-06

Loss of generator excitation caused a main turbine trip -followed by a reactor trip. Water hammer in the main steam turbine bypass line damaged three pipe supports.

1989-01-03

6.9 kV switchgear fire damaged control cables,, Prevented control of steam generator level after all RCS pumps tripped, problems with natural circulation: loss of forced coolant flow and excessive cooldown rate.