05000247/LER-2006-006, Re Automatic Actuation of Both Motor Driven Auxiliary Feedwater Pumps After Local Reset of the 21 Main Feedwater Pump During Corrective Maintenance and Troubleshooting of Turbine Governor Valve
| ML070370195 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 01/29/2007 |
| From: | Dacimo F Entergy Nuclear Indian Point 2 |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-07-010 LER 06-006-00 | |
| Download: ML070370195 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(iv), System Actuation 10 CFR 50.73(a)(2)(iv)(B), System Actuation 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 2472006006R00 - 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 Fred Dacimo Site Vice President Administration January 29, 2007 Indian Point Unit No. 2 Docket No. 50-247 NL-07-01 0 Document Control Desk U.S. Nuclear Regulatory Commission Mail Stop O-Pl-17 Washington, DC 20555-0001
Subject:
Licensee Event Report # 2006-006-00, "Automatic Actuation of Both Motor Driven Auxiliary Feedwater Pumps after Local Reset of the 21 Main Feedwater Pump During Corrective Maintenance and Troubleshooting of the Turbine Governor Valve"
Dear Sir:
The attached Licensee Event Report (LER) 2006-006-00 is the follow-up written report submitted in accordance with 10 CFR 50.73. This event is of the type defined in 10 CFR 50.73(a)(2)(iv)(A) for an event recorded in the Entergy corrective action process as Condition CR-IP2-2006-06885.
There are no commitments contained in this letter. Should you or your staff have any questions regarding this matter, please contact Mr. Patric W. Conroy, Manager, Licensing, Indian Point Energy Center at (914) 734-6668.
Sini Fred R. Dacimo Site Vice President Indian Point Energy Center E 2 Docket No. 50-247 NL-07-01 0 Page 2 of 2 Attachment: LER-2006-006-00 cc:
Mr. Samuel J. Collins Regional Administrator - Region I U.S. Nuclear Regulatory Commission U.S. Nuclear Regulatory Commission Resident Inspector's Office Resident Inspector Indian Point Unit 2 Mr. Paul Eddy State of New York Public Service Commission INPO Record Center
Abstract
While in Hot Standby for an outage, a local reset of the 21 Main Boiler Feedwater Pump (MBFP) turbine resulted in an automatic actuation signal to start both motor driven Auxiliary Feedwater Pumps (AFWP) and isolation of steam generator blowdown.
At the time of the event both AFWPs were in operation, and both MBFPs isolated and secured.
Troubleshooting was being performed on the 21 MBFP turbine high pressure steam governor valve.
After corrective maintenance was completed, control room (CR) operators attempted unsuccessfully to reset the 21 MBFP.
Subsequently, Maintenance locally reset the 21 MBFP and an auto start signal was initiated for actuation of the AFWPs and isolation of blowdown.
Continuing work activities resulted in another AFWP actuation and blowdown isolation.
The direct cause of the AFWP actuation was a signal from the 21 MBFP trip circuit as sensed by a pressure switch from the MBFP turbine control oil system.
The root cause was proceeding with the work and not stopping work activities after the CR reset failed and continuing the reset locally.
Contributing causes were identified for the root cause and those contributing causes and corrective actions are included in the corrective action program (CAP).
Corrective actions (CAs) for the direct cause of the AFWP actuation include dynamic testing of the MBFP auto stop oil pressure switch and testing of MBFP Lovejoy controls.
Any necessary CAs as a result of the testing will be implemented in accordance with the CAP.
The event had no effect on public health and safety.
NRC FORM 365 (6-2004)
(if more space is required, use additional copies of (If more space is required, use additional copies of (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 10CFR50.73(a) (2) (iv)
(A).
The licensee shall report any event or condition that resulted in manual or automatic actuation of any of the systems listed under 10CFR50.73(a) (2) (iv) (B).
Systems to which the requirements of 10CFR50.73(a) (2) (iv) (A) apply for this event include the AFWS.
This event is judged to meet the reporting criteria because the AFWS was actuated in accordance with design as a result of satisfying the requirements for initiation from the actuation circuitry from the 21 MBFP.
In accordance with design when MBFP turbine control auto-stop oil pressure falls below its setpoint limit as monitored by a pressure switch, a signal is sent to actuate the AFWPs.
Twice on November 30, 2006, the 21 MBFP turbine control oil pressure as sensed by pressure control switch PC-1154S met the criteria for actuation of the AFWPs.
Although the validity of the signal is uncertain at this time (whether an equipment malfunction of the pressure switch resulted in the AFWP actuation),
this event is being reported as an LER as verification testing exceeds 60 days.
As a result of this event no required safety system was unable to perform its safety function.
Therefore, there was no condition reportable as a safety system functional failure under 10 CFR 50.73(a) (2) (v).
Past Similar Events A review of the past two years of Licensee Event Reports (LERs) for events that involved an ESF actuation identified one LER.
LER-2005-003 reported actuation of both motor driven AFW pumps due to the trip of the 22 MBFP on low lube oil pressure during swap of the in-service lube oil cooler.
The cause of LER-2005-003 was an inadequate procedure for venting the lube oil coolers.
The cause of this LER was weak procedural guidance in the MBFP operating procedure.
The corrective actions for this event were briefing operations and enhancement of the FW system operating procedure.
The corrective actions for LER-2005-003 were revision of the system operating procedure for the MBFP lube oil system.
Therefore, those corrective actions would not have prevented this event.
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 the AFWS was in operation and the MBFPs were not aligned to deliver flow to the SGs.
The SGs had adequate FW flow from the AFWS to maintain SG water level.
Operators had alarms/indications alerting them to MBFP trip and actuation of the AFWS and procedures to direct proper actions.
Operators during this event recognized the MBFP trip and took appropriate actions in accordance with plant procedures.
There were no significant potential safety consequences of this event under reasonable and credible alternative conditions.
Loss of FW at full power is a credible alternative condition.
This event would be bounded by the analyzed event described in FSAR Section 14.1.9, Loss of Normal Feedwater.
A loss of one MBFP at power will result in a plant trip on low SG level if operator action does not correct the FW flow imbalance.
A Low-Low water level in any one SG initiates actuation of two motor-driven AFW pumps and a Low-Low water level in any two SGs actuates the steam driven AFW pump.
The AFW System has adequate redundancy to provide the minimum required flow assuming a single failure.
The analysis of a loss of normal FW shows that following a loss of normal FW, the AFWS is capable of removing the stored and residual heat plus reactor coolant pump waste heat, thereby preventing either over pressurization of the RCS or loss of water from the reactor core and returning the plant to a safe condition.