PNO-III-97-010, on 970219,diesel-driven CS Pump Found to Be Inoperable During Routine Surveillance Test.Reactor Operator Realized,Rods Were Moved Further than Expected.Actual Safety Significance of Error Minimal
| ML20138F992 | |
| Person / Time | |
|---|---|
| Site: | Zion File:ZionSolutions icon.png |
| Issue date: | 02/24/1997 |
| From: | Dapas M, Dave Hills NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | |
| References | |
| PNO-III-97-010, PNO-III-97-10, NUDOCS 9705060121 | |
| Download: ML20138F992 (2) | |
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February 24, 1997 PRELIMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-III-97-010 This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as
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initially received without verification or evaluation, and is basically all that is known by Region III staff (Lisle Illinois) on this date.
i Facility Licensee Emergency Classification Commonwealth Edison Co.
Notification of Unusual Event i
Zion 1 Alert j
Zion. Illinois Site Area Emergency
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Dockets: 50-295 General Emergency j
X Not Applicable
Subject:
AIT TO REVIEW IMPROPER CONTROL ROD MOVEMENT DURING REACTOR l
SHUTDOWN j
On February 21, 1997, the Unit ' reactor was at low power (about 7 percent), approaching shutdown because a diesel-driven containment spray pump was found to be inoperable during a routine surveillance test on -
February 19. The Technical Specifications required the plant be shut j
down by 2:20 p.m. if the pump was not restored.
At about 2 p.m. a reactor operator was inserting control rods to take i
the reactor to a very low power level, though still critical. He inserted two groups of control rods continuously for a total of about j
200 steps which resulted in reducing power well below the intended power j
i level. Normally, control rods would be inserted incrementally in a series of movements to reach the intended power level.
The control rod group insertion took the reactor subcritical (i.e. shut down). The reactor operator realized that he had moved the rods further than he should have. Without clear direction from shift management, the i
operator withdrew one of the rod groups approximately 80 steps, leaving the reactor in a subcritical condition.
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The actual safety significance of the error was minimal. The operator's actions, however, are of concern because the act of adding a significant amount of positive reactivity with the plant in hot shutdown was non-conservative decision making. Additionally, the operator's failure to e
9705060121 970224
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l PNO-III-97-010 clearly communicate plant conditions and the failure of shift management to provide proper oversight during this phase of the shutdown indicated a breakdown of command and control.
i As a result of this incident, licensee management plans to conduct training for the control room operating staff. The unit will remain shut down in a maintenance outage which the licensee had previously planned i
to begin in early May. The licensee is investigating the incident further and, based on the results of this investigation, licensee management will determine what additional actions are required.
An NRC Augmented Inspection Team (AIT) will be sent to the site to rview the circumstances surrounding the control rod movement incident and the licensee's response to it. The team will be led by a Region III(Chicago) branch chief and include personnel from the regional office and the Headquarters staff.
Region III will also issue a Confirmatory Action Letter to the licensee documenting the licensee's plans to evaluate the incident and to perform appropriate training of licensed operators and other corrective actions.
There has been news media interest in the incident. Region III will issuea news release on the formation of the AIT.
The State of Illinois will be notified. The information in this Preliminary Notification has been reviewed with licensee management.
Region III_ was notified of this incident at 11:00 a.m. on February 22, 1997 by the Senior Resident Inspector. This information is current as of 3 p.m. on February 24. 1997.
Contact:
DAVID HILLS MARC DAPAS (630)829-9733 (630)829-9628 4
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