05000286/LER-2009-005, Regarding Technical Specification Prohibited Condition Due to Exceeding Allowed Completion Time for an Inoperable 480 Volt Undervoltage/Degraded Grid Relay Caused by Personal Error
| ML092330109 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 08/07/2009 |
| From: | Joseph E Pollock Entergy Corp |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-09-102 LER 09-005-00 | |
| Download: ML092330109 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 2862009005R00 - NRC Website | |
text
En tergy Indian Point Energy Center 450 Broadway, GSB3 P.O. Box 249 Buchanan, N.Y. 10511-0249 Tel (914) 734-6700 J. E. Pollock Site Vice President NL-09-102 August 7, 2009 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop O-P1 -17 Washington, D.C. 20555-0001
SUBJECT:
Licensee Event Report # 2009-005-00, "Technical Specification Prohibited Condition Due to Exceeding the Allowed Completion Time for an Inoperable 480 Volt Undervoltage/Degraded Grid Relay Caused by Personnel Error" Indian Point Unit No. 3 Docket No. 50-286 DPR-64
Dear Sir or Madam:
Pursuant to 10 CFR 50.73(a)(1), Entergy Nuclear Operations Inc. (ENO) hereby provides Licensee Event Report (LER) 2009-005-00. The attached LER identifies an event where there was a Technical Specification prohibited condition for an inoperable 480 volt Bus Undervoltage/Degraded Grid Relay during past operation, which is reportable under 10 CFR 50.73(a)(2)(i)(B). This condition was recorded in the Entergy Corrective Action Program as Condition Report CR-IP3-2009-02664.
There are no new commitments identified in this letter. Should you have any questions regarding this submittal, please contact Mr. Robert Walpole, Manager, Licensing at (914) 734-6710.
Sincerely, JEP/cbr cc:
Mr. Samuel J Collins, Regional Administrator, NRC Region I NRC Resident Inspector's Office, Indian Point 3 Mr. Paul Eddy, New York State Public Service Commission LEREvents@lNPO.org
Abstract
On June 9, 2009, the inoperability during-past operation of a 480 volt time delay relay was identified during an NRC Problem Identification and Resolution (PI&R) inspection.
The inspection identified that a relay (62-1/3A) for 480 volt bus 3A had been documented in November 2007 for failing its As-Found acceptance tolerance including its Technical Specification (TS),
required value during performance of a surveillance test.
The previous months test also showed it failed.-these test criteria.
The relay in each test was calibrated to within tolerance within the TS allowed outage time.
In accordance with reporting guidelines,- -the-.failure: is assumed-to occur at the time of discovery unless there is firm evidence, based-'on review of relevant information, to indicate the discrepancy existed previously.
A corrective action (CA) was initiated for the November 2007 event and evaluated by engineering for past operability.
The engineer incorrectly concluded the relay had been performing satisfactorily and failed to recognize the significant drift as a degraded component.
The significant drift and repeat failures would indicate the-reiay Was-inoperable duringpa-o6peration and exceeded the TS allowed outage time. -The-relay was replaced in November 2007.
The apparent cause was personnel error due to inadequate knowledge of the drilft monitoring program and component drift performance.
CAs included reinforcement of management expectation for initiating CRs for as-found failures; development of expectations and guidance for evaluation and disposition of as-found surveillance failures, and re-evaluation of the functional failure determination for failed components.
The event had no effect on public health and safety.
(If more space.isrequired; use-additional copies of (If more space is required, use additional copies of NRC Form 366A) (17)
- The inoperable Agastat relay did not result in the loss of any safety function.
Agastat relay 62-1/3A is a time delay relay whose timer setting drifted outside its acceptance criteria which would have caused it to actuate later than required.
However, the relay would have still actuated upon demand.
Relay actuation later than specified could result in the motors running on the 480 volt bus to trip on overcurrent if a degraded grid condition continued before the relay transferred bus loads to the emergency diesels.
If the degraded voltage was accompanied by a
- - safety injection (SI) signal, the 10 second relay timer would have transferred the bus loads to the emergency diesel generators (EDG).
Engineering judgment concluded that the safeguards motors could have operated without damage.
Therefore, there was no safety system functional. failure reportable under 10CFR50.73(a) (2) (v).
PAST SIMILAR EVENTS A review-was performed:of Licefnsee Event Reports (LERs) for the past three years for any events reporting TS prohibited conditions due to relays out of calibration specification resulting in-inoperability.
No applicable LERs were identified.
SAFETY SIGNIFICANCE-.
This event had no significant effect on the health and safety of the public.
There were no actual safety consequences for the event because there were no UV or DGV conditions that challenged the bus or loads during past operation when the relay may have been out of specification.
The DGV protection on each 480 volt safety bus consists of two DGV relays arranged inma two-out-of-two-logic.- Functional actuation includes a time delay of 10 seconds if a coincident safety injection (SI) signal indicates accident conditions-exist and. a-time delay of 45 seconds-if no SI signal-is generated
-. (i.e., non-accident condition).
The DGV relay reported in this LER was for DGV protection for the non-accident condition.
When the two-out-of-two logic was made up, thefunction would not have been performed within 45 seconds.
The 10 second time was.operable so0if a two-out-of-two logic was made up coincident with an SI signal the function would actuate as designed.
The drift of the DGV relay timer setting would'-have caused it to actuate later than specified but it would have actuated on demand and provide 480 volt bus load transfer to the onsite emergency AC power source (EDGs).-
The actuation of the DGV relay later than specified could result in the -motors running on the 480 volt bus to trip on overcurrent if a degraded grid condition continued before the DGV relay actuated and transferred bus loads to the-EDGs.
Engineering judgment indicates this would not have occurred.
- - In the safety evaluation for TS Amendment No.
54, the original proposed time delay for DGV relays was less than or equal to 210 seconds for all-conditolns.' i The DGV fo6rnon-accident conditions was not proposed for equipment protectibn-but was selected to allow sufficient time for the offsite power transformer automatic tap qhanger to attempt to restore offsite power voltage thereby prevent-ing-*disconnection from the preferred power source.
The 210 second_'DGV time delay wastconsidered unacceptable for accident conditions and was revised to leSs-than or-equal to 10 seconds.
The safety evaluation report noted the 210 second time delay was reasonable for non-accident conditions when minimum safety equipment is operating, when accepting the proposed revision to 45 seconds.
The magnitude-of the DGV time delay, although exceeding the 45 second TS.limit,-was well below' the -210 seconds.