ML20079B063
| ML20079B063 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 12/29/1994 |
| From: | Noonan T DUQUESNE LIGHT CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9501040260 | |
| Download: ML20079B063 (4) | |
Text
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Beaver Vatey Power Station Shippen; port, PA 15077 0004 T
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We Fax 412) 9 Nuclear Operations December 29,1994 U. S. Nuclear Regulatory Comniission Attn: Document Control Desk Washington, DC 20555
Subject:
Beaver Valley Power Station, Unit No. 2 Docket No. 50-412, License No. NPF-73 Combineni Inspection Report 50-334/94-24 and 50412/94-25 Reply to Notice of Violation In response to the NRC correspondence dated November 29, 1994, and in accordance with 10 CFR 2.201, the attached reply addresses the Notice of Violation transmitted with the subject inspection report.
If there are any questions concerning this response, please contact Mr. N. R. Tonet, Manager, Nuclear Safety Department, at (412) 393-5210.
Sincerely, T. P. Noonan Attachment Mr. L. W. Rossbach, Sr. Resident Inspector ec:
Mr. T. T. Martin, NRC Region I Administrator Mr. G. E. Edison, Sr. Project Manager Mr. J. C. Linville, Chief, Projects Branch No. 3, Division of Reactor Projects 9EllVEllNG QU A LITY ENERGY 9501040260 941229 1
[DR ADOCK 0500 4
DUQUESNE LIGHT COMPANY Nuclear Power Division Beaver Valley Power Station Unit No. 2 Reply to Notice of Violation Combined Inspection Report 50-334/94-24 and 50-412/94-25 Letter Dated November 29, 1994 i
VIOLATION (Severity Level IV; Supplement I)
Descriotion of Violation (50-412/94-25-01) 10 CFR Part 50, Appendix B,
Criterion XVI, " Corrective Actions,"
- states, in
- part, that measures shall be established to assure that conditions adverse to
- quality, such as
- failures, malfunctions, deficiencies, deviations, defective material and equipment, and nonconformances are promptly identified and corrected.
Contrary to the above, as of October 21, 1994, established measures did not assure that conditions adverse to quality were promptly identified and corrected.
Specifically, the investigations of an unusually dim white control power light for emergency switchgear ventilation fans 2HVZ-FN261A on October 30, 1993, and 2HVZ-FN261B on September 24, 1994, failed to identify that the standby fan would not start if called upon following the loss of the running fan except when started by the emergency diesel sequencer.
Equipment maintenance history was not used to identify that a trend of similar problem descriptions of a dim white control power light has existed since 1989.
Discussion of and Reason for the Violation A
review of the circumstances surrounding the violation identified the following reasons for its occurrence.
The activities associated with Maintenance Work Request (MWR) 015912, which was written to investigate a dim white control power light for emergency switchgear ventilation fan 2HVZ-FN261A, failed to identify and correct a
potential " sneak" circuit path that could prevent the fan from auto starting when in the standby mode under certain situations.
Troubleshooting activities performed on October 30,
- 1993, did not identify any problems with the circuit.
The reason for the failure to identify the " sneak" circuit was inadequate problem identification combined with the actions associated with establishing the equipment clearance to support troubleshooting activities, which eliminated the dim light condition.
Therefore, the dim light condition could neither be observed nor re-established during the troubleshooting activities.
The Maintenance Hiatory Review Program did not identify any problem trend with the emergency switchgear ventilation supply fans because the equipment maintenance history did not meet the program screening criteria.
When MWR 015912 was initiated on January 14, 1993, no other MWR had been written against the emergency switchgear ventilation supply fans since February 9, 1990, a period of over 35 months.
Inadequate problem identification was the basic reason the circuit deficiency was not identified.
sply to Notics of Violation Combined Inspection Report 50-334/94-24 and 50-412/94-25 Letter Dated November 29, 1994 Page 2 The activities associated with MWR
- 035001, which was written to investigate relay 162-HVZBB in the control circuit for emergency switchgear ventilation fan 2HVZ-FN261B, also failed to identify and correct the potential " sneak" circuit path that could prevent the fan from auto starting when in the standby mode under certain situations.
This relay remained energized once the " sneak" circuit was established and thereby prevented fan 2HVZ-FN261B from starting in the standby mode.
This MWR was voided by the Nuclear Shift Supervisor (NSS) on September 24, 1994, the same day it was written.
The NSS was able to auto start both trains of the emergency switchgear ventilation fans by first placing the control switch in
" pull to lock."
He considered this condition a peculiarity of the system
- design, but not an equipment deficiency.
Therefore, the decision to accept the dim light condition as part of the system design and not pursue any permanent corrective action prevented the identification and correction of the potential " sneak" circuit path.
The Beaver Valley Power Station (BVPS)
Unit 2 Probabilistic Risk Assessment (PRA) has identified a
high risk significance for the emergency switchgear ventilation system, but this information was not used by the Operations and Maintenance personnel involved in the events leading up to this violation.
Factoring these PRA results into the MWR scheduling process and the efforts to identify a particular reason for the dim light condition would likely have resulted in a
higher level of attention to this condition and may have resulted in a
timely identification of the deficiency.
Our conclusion, however, is that the overriding reason for the failure to promptly identify and correct the circuit deficiency was inadequate problem identification as previously discussed.
Corrective Actions Taken Troubleshooting efforts identified a potential " sneak" circuit path in the emergency switchgear ventilation supply fan control circuit.
The potential
" sneak" circuit consisted of a
path through the resistor of the white breaker position indicating light and a time delay relay (relay 162-HVZAB for fan 2HVZ-FN261A and relay 162-HVZBB for fan 2HVZ-FN261B) of the fan in standby.
With the " sneak"
- circuit, momentary pressure drops on the running emergency switchgear ventilation supply fan caused the time delay relay of the standby fan to energize and incorrectly
" seal-in."
Once " sealed-in" the relay would time-out and attempt to start the standby fan, even though the pressure of the running fan had by then recovered.
When the running fan pressure recovered, a
maintained trip signal was placed on the standby fan per design.
With simultaneous maintained close and trip
- signals, the standby fan would become trip-free and lock up, unable to respond to any actual trip of the running fan.
When started by the emergency diesel generator sequencer, the fans were unaffected by the " sneak" circuit path.
.4 -.
R ply to Notics of Violation-Combined Inspection Report 50-334/94-24 and 50-412/94-25 Letter Dated November 29, 1994 Page 3-4 Design Change Package 2124 was issued to correct the deficiency by installing a
blocking diode in the emergency switchgear supply fan circuitry.
This eliminated the potential " sneak" circuit path.
Actions Taken to Prevent Recurrence 1.
A copy of the Beaver Valley Power Station (BVPS) PRA for both Unit 1
and Unit 2 and a BVPS PRA summary document for both units has been placed in the control room.
The summary document has been discussed in operator shift briefings at each respective unit to provide operators a general awareness of the PRA process and results.
Also, this Notice of Violation has been discussed in operator shift briefings to provide an operator awareness of the events discussed in the violation.
2.
To enhance general knowledge of the Beaver Valley Power Station PRA, training will be conducted as follows:
a)
Engineering Support Personnel Continuing Training for the First Quarter 1995 and Third Quarter 1995 training modules.
j b)
The Initial Licensed Operator Training Program prior to the completion of the next initial licensed operator training.
i c)
Operator License Retraining for 1995 presently scheduled to be completed by July 7, 1995.
1 3.
Maintenance and Operations supervision will be retrained on Nuclear Power Division Administrative Procedure (NPDAP) 7.5, "The Maintenance Work Request" requirements for completing the
" Initial Problem / Failure Description" field on. the MWR.
The training will emphasize management's expectations on the level of awareness and detail required for this field and the importance this has on the effective implementation of the MWR program.
The level of detail provided should be commensurate with the safety significance of the equipment.
This training will be completed I
by April 30, 1995.
Date When Full Compliance Will Be Achieved Full compliance was achieved with the installation of a blocking diode in the emergency switchgear ventilation supply fan control circuit via Design Change Package
- 2124, which was completed by November 14, 1994.
i