05000247/LER-2008-002, Re. Technical Specification Prohibited Condition Due to Exceeding the Allowed Completion Time for an Inoperable Engineered Safety Feature Actuation System Automatic Actuation Logic & Actuation Relay Caused
| ML081560205 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 05/27/2008 |
| From: | Joseph E Pollock Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-08-076 LER 08-002-00 | |
| Download: ML081560205 (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)(i) |
| 2472008002R00 - NRC Website | |
text
Indian Point Energy Center 450 Broadway, GSB P.O. Box 249 nBuchanan, N.Y. 10511-0249 ILLffffI Tel (914) 734-6700 J. E. Pollock Site Vice President May 27, 2008 Indian Point Unit No. 2 Docket No. 50-247 NL-08-076 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Stop O-P1-17 Washington, D.C. 20555-0001
Subject:
Licensee Event Report # 2008-002-00, "Technical Specification Prohibited Condition Due to Exceeding the Allowed Completion Time for an Inoperable Engineered Safety Feature Actuation System Automatic Actuation Logic and Actuation Relay Caused by Improper Relay Wiring"
Dear Sir or Madam:
Pursuant to 10 CFR 50.73(a)(1), Entergy Nuclear Operations Inc. (ENO) hereby provides Licensee Event Report (LER) 2008-002-00. The attached LER identifies an event where there was a Technical Specification prohibited condition that exceeded the Allowed Completion Time for an Inoperable Engineered Safety Feature Actuation System Automatic Actuation Logic and Actuation Relay, 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-IP2-2008-01482.
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, J. E. Pollock Site Vice President Indian Point Energy Center cc:
Mr. Samuel J Collins, Regional Administrator, NRC Region I NRC Resident Inspector's Office, Indian Point 2 Mr. Paul Eddy, New York State Public Service Commission INPO Record Center AJggz
Abstract
On March 27, 2008, during Safety Injection (SI) and Black Out testing, with the unit shutdown for a refueling outage, a 480 V breaker {BKR} on Safeguards Bus 2A
{ED) did not close during a surveillance test.
Troubleshooting discovered that SI Logic Train A, relay 3-2, contact 17-21, when closed had high contact resistance.
Relay 3-2 is part of the Engineered Safety Feature Actuation System (ESFAS),
whose design function is to actuate safeguards equipment required to mitigate an accident.
On March 28, 2008, troubleshooting discovered relay 3-2 did not have wires associated with 23 Fan Cooler Unit (FCU)
Breaker connected to it in accordance with plant design.
The wires were found landed on an adjacent SI Logic Train A relay 3-3.
Subsequently equivalent wires on the SI Logic Train B relays, 3-12 and 3-13, were discovered to be similarly mis-wired.
The incorrect wiring associated the 23 FCU with Bus 5A rather than its assigned Bus 2A.
If power was lost on Bus 5A during an SI, the mis-wiring would prevent the automatic start of the 23 FCU even though its assigned Bus 2A was energized.
The apparent cause of the circuit anomaly was an improperly implemented design change by the original plant installer in 1973.
The design schematic was properly revised by the design change but the wiring lists and plant were not.
The specific cause can not be determined due to the passage of time.
Corrective actions included re-wiring of relay contacts in accordance with re-verified design documents.
An extent of condition was performed and no additional wiring anomalies were identified. The event had no effect on public health and safety.
(If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) (17)
Event Analysis
The event is reportable under 10 CFR 50.73(a) (2) (i)
(B),
operation or condition which is prohibited by the plant Technical Specification (TS).
TS 3.3.2, requires Safety Injection, Automatic Actuation Logic and Actuation Relays to be OPERABLE in modes 1, 2, 3 & 4.
The required relays were not operable since they would not have performed their required function assuming a single failure of one diesel to supply power to bus 5A and loss of offsite power during a design basis accident.
In this scenario bus 2A is available but the associated 23 FCU can not receive an automatic start as a result of its actuating relay being restrained due to no power to bus 5A.
The relays automatically actuate the Fan Cooler Units.
TS 3.6.6, "Containment Spray System and Containment Fan Cooler Unit (FCU)
System,"
LCO requires two trains of containment spray and three trains of FCUs OPERABLE in modes 1, 2, 3
& 4.
The required FCU trains would not have performed the required function assuming a single failure of one diesel to supply power to bus 5A and loss of offsite power during a design basis accident.
In this scenario the 5A train is unavailable and the 2A train is degraded since the 23 FCU does not receive a start.
The 23 FCU is however available for manual start.
No safety system functional failure (SSFF) occurred.
A SSFF could occur if all power was lost to bus 5A.
This would result in no power to the 21 and 22 FCU as well a's the 21 Containment Spray Pump.
It would also result in relay 3-3 and 3-13 not actuating the 23 FCU on bus 2A.
No SSFF has occurred because there has been no reported loss of offsite power to bus 5A concurrent with a failure of the capability to power bus 5A with its assigned EDG during times applicable safeguards equipment were required to be operable.
In accordance with the guidelines of NUREG-1022, an additional random single failure does not have to be assumed in that system for reportability.
PAST SIMILAR EVENTS A review was performed of Licensee Event Reports (LERs) for the past three years for any events that involved mis-wiring of logic relays or loss of emergency bus.
No LERs were identified that reported similar failures.
SAFETY SIGNIFICANCE
This event had no effect on the health and safety of the public.
There were no actual safety consequences for the event because there were no accidents requiring the affected safety equipment during the time of the anomaly.
- However, if an event had occurred with the condition mentioned above (loss of bus 5A),
then minimum safeguards equipment would not have automatically started as required by design,.
The option for FCU manual start was always available to mitigate the consequences of this postulated scenario.
A risk assessment evaluated the condition with 23 FCU breaker out of service and determined there is no measureable impact on Core Damage Frequency (CDF).
The incremental CDF change of 1.38E-8 events per year resulted in a CDF of 1.7887E-5 events per year from a CDF of 1.7874E-5 events per year.