05000247/LER-2009-003, Regarding Loss of Single Train 21 Pressurizer Backup Heater Required for Remote Plant Shutdown from the Control Room Due to an Inoperable Breaker
| ML092330122 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 07/27/2009 |
| From: | Joseph E Pollock Entergy Corp, Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-09-096 LER 09-003-00 | |
| Download: ML092330122 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 2472009003R00 - NRC Website | |
text
En tergy Indian Point Energy Center 450 Broadway, GSB P.O. Box 249 Buchanan, N.Y. 10511-0249 Tel (914) 734-6700 J. E. Pollock Site Vice President NL-09-096 July 27, 2009 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop O-P1-17 Washington, D.C. 20555-0001
SUBJECT:
Licensee Event Report # 2009-003-00, "Loss of Single Train 21 Pressurizer Backup Heater Required for Remote Plant Shutdown from the Control Room Due to an Inoperable Breaker" Indian Point Unit No. 2 Docket No. 50-247 DPR-26
Dear Sir or Madam:
Pursuant to 10 CFR 50.73(a)(1), Entergy Nuclear Operations Inc. (ENO) hereby provides Licensee Event.Report (LER) 2009-003-00. The attached LER identifies an event where the Technical Specification 3.3.4 Remote Shutdown safety function for single train 21 pressurizer backup heater was inoperable thereby not available for remote shutdown from the control room, which is reportable as a safety system functional failure under 10 CFR 50.73(a)(2)(v). This condition was recorded in the Entergy Corrective Action Program as Condition Report CR-IP2-2009-01965. An 8-hour notification under 10CFR50.72(b)(3)(v) should have been made but was not initially recognized as being required. CR-IP2-2009-02072 was recorded in the CAP for failure to make this notification.
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 2 Mr. Paul Eddy, New York State Public Service Commission LEREvents@inpo.org
Abstract
On May 28,
- 2009, after completion of quarterly surveillance 2-PT-Q54,"Pressurizer Level Bistable Test," and return of the Pressurizer Level Defeat switch (L-460A) to its original position, control room (CR) alarm (Pressurizer Low Level 18% and 5%)
came in and cleared, and (Pressurizer Heater Group Tripped) alarmed due to the trip of Pressurizer Heater Group 21 and the Modulating Heater Group.
The breakers for these components opened and Operators attempted to reclose the breakers but were unable to re-close the breaker for the 21 pressurizer backup (B/U) heater.
Operators were able to close the breaker for the 22 pressurizer B/U heater and re-close the breaker for the modulating heaters.
Technical Specification (TS) 3.3.4.A (Remote Shutdown) was entered for an inoperable 21 pressurizer backup (B/U) heater.
Troubleshooting was initiated and the anti pump lever for the 21 pressurizer B/U heater breaker was manually reset and the breaker closed.
The apparent cause of the trip of the pressurizer heaters was a degraded switch (L-460A) where a dead spot caused an intermittent interruption of continuity when the switch was rotated to the Defeat 3 position.
The interruption disrupted the input to pressurizer level bistables and momentarily actuated the bistables causing the alarm and trip of the breakers for the pressurizer heaters.
The inability to reset and re-close the breaker for the 21 pressurizer B/U heater was due to a misaligned control relay trip (anti-pump) lever.
Corrective actions included troubleshooting breaker 52/PBUI, realignment of the anti pump lever, testing, breaker cycling and closure.
Switch L-460A and the control relay will be replaced and the
.cubicle rail for the breaker (52/PBUl) will be repaired.
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)
Past Similar Events A review was performed of the past three years of Licensee Event Reports (LERs) for events that involved inoperable remote shutdown functions.
No unit 2 LERs were identified.
However, unit 3 reported in LER-2008-002 a similar loss of their single train 31 pressurizer heater.
The unit 3 event was a different cause as that event was due to a failed pressurizer heater transformer.
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 or transients requiring shutdown outside the CR.
Shutdown outside the CR could also be accomplished with one of the remaining pressurizer heaters through use of local breaker operation or without the use of the heaters.
Operation of the 21 pressurizer B/U heater breaker from the remote shutdown switch would have operated prior to the surveillance testing as the test switch (L-460A) is not part of the actuating circuit.
The protective function of the circuit would have operated properly.
The condition resulted during surveillance testing of pressurizer level bistables.
In accordance with NUREG-0800, Section 7.4, shutdown remote from the CR is not an event analyzed in the USFAR for accident analysis (Chapter 14).
Specific scenarios are not specified on which the adequacy of shutdown capability remote from the CR is evaluated.
A recognized type of event that could force the evacuation of the CR and the need to shut down remote from the CR is smoke from a fire.
Fire damage limits as they impact safe shutdown do not require consideration of an additional random single failure in the capability to safely shut down.
Therefore, application of single failure to remote shutdown is applicable only to other events that could cause the CR to become uninhabitable.
These events would not result in consequential damage or unavailability of systems required for safe shutdown.