ML20072Q854
| ML20072Q854 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 08/26/1994 |
| From: | Rosenblum R SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9409120254 | |
| Download: ML20072Q854 (4) | |
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Southam Califomia Edison Company 23 PARMER STREET 1RVINE, CALIFORNIA 92718 aicsaae u. nosEsstuu race ~o =
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August 26, 1994 i
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S. Nuclear Regulatory Commission j
Document Control Desk Washington, D.C.
20555 Gentlemen:
Subject:
Docket Nos. 50-361 and 50-362 San Onofre Nuclear Generating Station, Units 2 and 3
References:
(1)
Letter, Mr. Thomas P. Gwynn (NRC:RIV) to.Mr.
Harold B.
Ray (Edison), dated July 12, 1994 (Inspection Report 50-361/362, 94-16)
)
(2)
Letter, Mr. Richard M. Rosenblum (Edison) to NRC, dated August 11~,
1994.
(3)
Letter, Mr. Richard M. Rosenblum (Edison) to NRC, dated August 5, 1994 Reference 1 transmitted the results of NRC Inspection Report No.
50-361/362 94-16, and included a Notice of Violation for failure to follcw procedures.
Reference 1 states in part: "We are particularly concerned regarding the potential implications for the operator performance that are implicit in the high pressure safety injection pump damage incidents.
As a result,-in conjunction with your response to the enclosed Notice, we request that you address the measures that have been or will be initiated to ensure that adequate management attention is provided to resolve the operator performance aspects of this violation."
Reference 2 responded to the Notice of Violation.and stated that our comments addressing your concern would Da provided in a separate transmittal.
This letter provides our response, and also discusses a third instance involving misoperation of a High Pressure Safety Injection (HPSI). pump which occurred only recently (Reference 3).
SUMMARY
OF EVENTS At 0220 on November.3, 1993, during refueling activities preparatory to filling the refueling cavity, HPSI pump 3P018 was started and run for 45 minutes without a discharge flow path.
Per procedure, it was intended to be run for one hour with a flow f
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August 26, 1994 l
path to the Refueling Water Storage Tank.
Forty-five minutes into the run, steam uas observed in the HPSI 3P018 pump room and the pump was stoppec.
The steam in the room was predominantly a result of HPSI 30018 suction relief valve lifting.
Local investigation identified that the Train
'B' Emergency Core Cooling System (ECCS) common mini-flow block valve 3F"9347 was closed, and l
the pump overheated.
This event was caused by a failure to l
closely follow procedural requirements when transferring valve l
control from one process to another.
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At approximately 2330 that same day, HPSI 3P019 was operated beyond design flow limits.
No immediate anomalies were noted during the run.
This happened as HPSI pumps 3P017 and 3P019 were l
aligned for use as convenient water transfer sources (a nonsafety-l related function) for the planned refueling activities.
During j
the period from November 4 to November 23, HPSI 3P019 was run three more times to support. additional refueling cavity fills and a reactor coolant system fill.
No anomalies were noted during these runs as well.
At 1632, on November 24, 1993, HPSI 3P019 was l
started for a containment emergency sump check valve test and was l
identified to have excessive vibration.
Following an additional run, HPSI 3P019 was declared inoperable at 1651 for its ECCS l
function due to failure to develop adequate discharge pressure.
l This misoperation occurred as a result of several factors: 1) the operators were unaware, as were most others, that the pumps could operate beyond design basis flow using normally available flow paths; 2) the operators' mind-set to maintain adequate flow as a result of the previous event; and 3) the operators' failure to closely follow the procedure which had been prepared for this refueling evolution.
l A third event occurred on August 3, 1994, when out-of-service HPSI pump 2P017 was operated for approximately two hours without forced cooling water flow to the pump motor or seals.
This pump run was l
one in a series of inservice test (IST) runs being conducted to evaluate and resolve anomalous pump vibration.
During the period from June 21 (when the pump was first removed from service) to August 3, 1994, HPSI 2P017 had been operated a total of 12 times.
l In all other cases, cooling water was provided as required.
l Edison's investigation concluded that both the motor and pump seals were not damaged as a result of this misoperation.
In this case a change in plant operation which implemented the current design basis configuration of the cooling water system (one train in service, one in standby) may have contributed to the error.
The previous 12 years operating with both trains of cooling water in service likely established a mind-set that reduced the operators' alertness to the need to verify cooling water was i
available prior to starting the pump. Additionally, the presence l
of continuously illuminated cooling water low-flow alarms, and a failure to closely follow procedural requirements contributed to the error.
D,ocument Control Desk August 26, 1994 SYSTEM CONFIGURATION HPSI pumps are operated over an unusually wide spectrum of their capability.
They are operated at high discharge pressure - low flow, low discharge pressure - high flow conditions, and in several flow path configurations - e.g.,
safety injection mode, recirculation mode, test modes, and various refueling evolution modes.
The pumps, as we now know, are susceptible to damage at both ends of their operating range.
MANAGEMENT ACTIONS TO RESOLVE PERFORMANCE DEFICIENCIES Edison has reviewed these three events carefully at several levels of management.
We have concluded that a lack of attention to detail by operators in following procedures was present to a degree in all three events.
Accordingly, we are applying enhanced management emphasis on attention to detail in following procedures to correct the performance weakness noted here.
Other management actions included having a stand-down period during which Operations management personally instructed all crews on management expectations for the control and execution of work.
In addition, Edison has taken disciplinary action for the individuals involved, including removing one operations supervisor from shift responsibilities for an indefinite period.
Operations Division Experience Reports 3-93-31 and 3-94-11, which evaluated the 3P018 and 3P019 events, were issued to all operators for required reading.
A similar evaluation is being performed for the 2P017 event and upon completion will also be issued to all operators as required reading.
As lessons learned, these three events will also be incorporated into operator requalification training.
Although not common to all three events, Edison has also concluded that program weaknesses contributed #o some of the events.
These weaknesses include a lack of knowledge on the part of the operators (and others) that excess flow conditions could be achieved that would result in pump damage.
As corrective action, enhanced controls during outages, addition of precautionary notes to procedures, and instruction of operators on HPSI design / operation will be implemented.
Lastly, Edison will reemphasize in operator training the need to verify cooling water availability when starting train-aligned components.
MANAGEMENT ACTIONS CONCERNING ROOT CAUSE ANALYSIS Reference 1 also stated in part:
we believe that effective management oversight of the root cause analysis and corrective actions for the high pressure safety injection pump damage...
would have identified and corrected these violations months
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D,ocum'ent Control Desk
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~ before this inspection.
These violations are also of concern because they did not appear to have received adequate management attention until addressed by the staff."
l When the HPSI 3P019 damage was discovered, human performance factors were initially assessed and operators interviewed.
However, these actions were not documented.
Circumstances surrounding the event, and the belief that excess flow sufficient to damage the pump could not be achieved in actual operation, initially caused investigators to discount the significance of operator performance.
Edison recognizes the value in examining the human performance l,
aspects promptly.
We understand that the failure to perform a formal human performance evaluation promptly after such an event could result in the loss of data necessary to fully understand the root cause of equipment damage.
Therefore, Edison will promptly j
perform a documented preliminary human performance evaluation l
after events resulting in major equipment damage are identified.
l We believe that improved performance in this area will lead to more effective corrective actions.
l l
If you have any additional questions, please contact me.
Sincerely, 7
/
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cc:
L. J.
Callan, Regional Administrator, NRC Region IV A.
B.
Beach, Director, Division of Reactor Projects, NRC Region IV K.
E.
Perkins, Jr.,
Director, Walnut Creek Field Office, NRC Region IV J. A. Sloan, NRC Senior Resident Inspector, San Onofre Units 2 &3 M.
B.
Fields, NRC Project Manager, San Onofre Units 2 & 3 l