NRC Staff to Hold Conference with Commonwealth Edison to Discuss Apparent Violations at Zion Nuclear Power Station




801 Warrenville Road, Lisle IL 60532

CONTACT:    Jan Strasma (630) 829-9663/e-mail:
Angela Dauginas (630) 829-9662/e-mail:


June 23, 1997


The Nuclear Regulatory Commission staff will meet Thursday, July 3, with representatives of Commonwealth Edison Company for a predecisional enforcement conference on apparent violations associated with improper reactor control rod movement during a Unit 1 shutdown February 21 at the Zion Nuclear Power Station.

The meeting will also include other apparent violations identified during subsequent NRC inspections at the Zion plant.

The meeting will be at 10 a.m. in the Third Floor Conference Room, NRC Region III Office, 801 Warrenville Road, Lisle, Illinois. The meeting will be open to public observation.

NRC inspectors reviewing the February 21 incident concluded there was a breakdown in the management of the Unit 1 shutdown and cited numerous examples of plant operators and management failing to follow procedures. In the incident, a reactor operator improperly inserted control rods into the reactor core during a plant shutdown and then, without conferring with plant supervision, began to withdraw the control rods to return the reactor to a very low power level.

There were no actual safety consequences associated with the control rod movements, but the NRC inspection found extensive deficiencies in control room operating practices, poor communications, and inadequate supervision.

Besides the apparent violation for failing to follow procedures, the inspectors identified another violation for inadequate corrective actions to promptly address the operator performance problems during the shutdown incident and to correct previous operator deficiencies.

Both Zion units remain in extended outages to improve the performance of plant staff and management and for plant modifications.

Two additional issues to be discussed in the enforcement conference occurred after the February 21 Unit 1 shutdown.

The first issue occurred on February 22, the day following the Unit 1 shutdown. All three electrical channels for a Unit 1 reactor cooling system flow indicator were taken out of service for maintenance at a time when at least one of the parallel channels was required to be operable.

In the second issue, the plant staff determined on March 7 that gases had gradually accumulated at the top of the Unit 2 reactor, forming a bubble that lowered the reactor water level. The plant had been shut down since September of last year for refueling and maintenance.

The decreased reactor water level was not detected because the level measuring system was not required to be in service, according to plant procedures.

Another measuring system would have detected the level had it declined another 4 feet, a point which is still well above the top of the reactor fuel core. A decrease to this point, which would take a number of days, could have affected the system normally used for circulating cooling water through the reactor while the plant is shut down.

On March 8 plant operators vented the gas from the Unit 2 reactor. About 6,900 gallons of water was needed to fill the void. Operators also vented the Unit 1 reactor; about 1,090 gallons of water was required to fill the void.

The gas accumulation incident involved several apparent violations, including inadequate corrective actions from a previous instance of gas accumulation last September, failure to have adequate procedures for operation during an extended shutdown and to prevent the undetected buildup of gases, and failure to submit telephone and written reports to the NRC on the incident.

The decision to hold an enforcement conference does not mean the NRC has determined that a violation has occurred or that enforcement action will be taken. Rather, the purpose is to discuss apparent violations, their causes and safety significance; to provide the licensee an opportunity to point out any errors that may have been made in the NRC inspection report; and to enable the company to outline its proposed corrective actions.

No decision on the apparent violations or any contemplated enforcement action, such as a fine, will be made at this conference. Those decisions will be made by senior NRC officials at a later date.

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