05000364/LER-2005-001, Re Gas Binding of the Unit 2 a Train High Head Safety Injection Pump
| ML060320726 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 01/31/2006 |
| From: | Stinson L Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-06-0068 LER 05-001-00 | |
| Download: ML060320726 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 3642005001R00 - NRC Website | |
text
1. M. Stinson (Mike)
Southern Nuclear Vice President Operating Company, Inc.
40 lnverness Center Parkway Post Office Box 1295 Birmingham, Alabama 35201 lel 205.992.5181 Fax 205.992.0341 January 31, 2006 Docket No.: 50-364
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SOUTHERN k COMPANY Energy to Serve Your WorldY NL-06-0068 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Joseph M. Farley Nuclear Plant - Unit 2 Licensee Event Report 2005-001 -00 Gas Binding of the Unit 2 A Train High Head Safety Iniection Pump Ladies and Gentlemen:
Joseph M. Farley Nuclear Plant - Licensee Event Report (LER) No. 2005-001 -00 is being submitted in accordance with 10 CFR 50.73(a)(2)(i)(B).
This letter contains no NRC commitments. If you have any questions, please advise.
Sincerely, Enclosure: Licensee Event Report 2005-001 -00 cc:
Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Mr. J. R. Johnson, General Manager - Plant Farley RTYPE: CFA04.054; LC# 14384 U. S. Nuclear Rewlatorv Commission Dr. W. D. Travers, Regional Administrator Mr. R. E. Martin, NRR Project Manager - Farley Mr. C. A. Patterson, Senior Resident Inspector - Farley
J. R. Johnson, Nuclear Plant General Manager 1334-899-5 156 URC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION 6-2004)
LICENSEE EVENT REPORT (LER)
(See reverse for required number of digitslcharacters for each block)
- 1. FACILITY NAME Joseph M. Farley Nuclear Plant - Unit 2 I
I I APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06/30/2007
, the NRC ma) not conduct or sponsor, and a person is not required to respond to, the information collection.
- 2. DOCKET NUMBER 05000 364
- 4. TITLE Gas Binding of the Unit 2 A Train High Head Safety Injection Pump
CAUSE
A On December 4,2005, with the reactor at 29 percent power, while shifting on-service trains of High Head Safety Injection (HHSI) during power ascension following a refueling outage, the 2A HHSI Pump was found I
- 3. PAGE 1 OF 4 YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
IXI NO to be inoperable, due to gas accumulation in its suction line. Although the actual time of inoperability is not I
- 5. EVENT DATE SYSTEM BQ SUBMISSION I
I DATE known, it is apparent that the pump became inoperable some time prior to Mode 3 entry on November 30, 2005. On December 4,2005, at 0358, the A Train HHSI Pump was started, and the B Train HHSI Pump was secured. Charging and seal injection flow went to zero and then began to oscillate. The operator immediately restarted the B Train HHSI Pump to restore flow and secured the A Train HHSI Pump. TS Limiting Condition for Operation (LCO) 3.5.2 Required Action Statement (RAS) for inoperable A Train Emergency Core Cooling System (ECCS) was entered at 0400. The swing HHSI Pump was aligned to A Train, and TS LC0 3.5.2 was exited at 0635. Root cause investigation determined the cause of the event to be gas bubble
- 12. LICENSEE CONTACT FOR THlS LER FACILITY NAME TELEPHONE NUMBER (Include Area Code)
MONTH 12
- 14. SUPPLEMENTAL REPORT EXPECTED ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines) formation in the pump suction line due to excessive variations in Volume Control Tank (VCT) pressure over Y
COMPONENT P
a short time period. After discovery of the gas intrusion, the A Train HHSI pump was vented, tested, and returned to service. Operations personnel have been trained on this event, and procedures have been enhanced to address the possibility of gas intrusion under these conditions.
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFRS: (Check all that apply) 20.2201(b) 20.2203(a)(3)(i) 50.73(a)(2)(i)(C) 50.73(a)(2)(vii) 20.2201(d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(A) 50.73(aX2)(viii)(A) 20.2203(a)(1) 20.2203(a)(4) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(2)(i) 50.3qc)(l )(i)(A) 17 50.73(a)(2)(iii) 50.73(a)(2)(ix)(A) 20.2203(a)(Z)(ii) 50,36(c)(l)(ii)(A) 50.73(a)(2)(iv)(A) 50.73(a)(2)(x) 20.2203(a)(2)(iii) 50.36(~)(2) 50.73(a)(2)(v)(A) 73.71(a)(4) 20.2203(a)(2)(iv) 50.46(a)(3)(ii) 50.73(a)(2)(v)(B) 73.71(a)(5) 20.2203(a)(2)(v) 50.73(a)(2)(iXA) 50.73(a)(2)(v)(C)
OTHER 17 20.2203(a)(2)(vi)
El 50.73(a)(2)(i)(B) 50.73(a)(2)(v)(D)
Specify in Abstract below or in =
(If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) (17)
FACILITY NAME (1)
Joseph M. Farley Nuclear Plant - Unit 2 Root cause investigation determined the cause of the event to be gas bubble formation in the A Train HHSI Pump suction line due to pressure transients on a system saturated with dissolved gas. These transients occurred due to insufficient procedure guidance to maintain relatively constant VCT pressure during VCT level variations.
Safety Assessment
DOCKET (2)
NUMBER 05000364 LER NUMBER (6)
Considering component/system operational and venting activities at the time of the occurrence, only one train was affected; therefore, this event did not constitute a safety system bctional failure. The B Train pump and swing pump suction lines, which are at a lower elevation than the A Train pump, were verified to be unaffected by this event. During the period in question, two operable HHSI pumps were available at all times. Prior to the December 4 event, the B Train pump was operable and the swing pump was operable and aligned to B Train. During the December 25 event, the swing pump was aligned to the A Train and would have started automatically in the event of an A Train pump trip. The swing pump could be manually started from the Main Control Board throughout both events.
I Only one train of HHSI was affected, and a safety injection was not required; therefore, the safety and health of the public were unaffected by this event.
REVISION NUMBER YEAR Additionally, the system alignment at the time of the occurrence differs significantly from the alignment assumed in response to an accident. Therefore, firm conclusions, regarding the expected performance of the 2A pump in the post-accident alignment, based solely on the observed response at the time of this occurrence is not prudent. The post-accident alignment transfers the pump suction source to a higher pressure source (Refueling Water Storage Tank (RWST)) and significantly reduces the discharge-side system resistance of the PU~P(S).
2005 001 00 SEQUENTIAL NUMBER The 2A HHSI pump would have been expected to purge the gas from the suction side in a reasonably short period of time without any near-term mechanical damage and would have then been expected to return to near pre-occurrence hydraulic performance. This is supported by the indications observed during the December 4 event, where flow initially dropped to zero but then began to recover as evidenced by flow oscillations.
While the exact time required to purge the gas through the pump is not known, the greater the suction flow, the shorter the expected purging duration.
In order to assess the impact of a delay in ECCS flow delivery associated with purging of a gas void, NRC FORM 366 (7-2001) U.S. NUCLEAR REGULATORY COMMISSION (7-2001)
LICENSEE EVENT REPORT (LER)
I I
I NARRAllVE (If more space is required, use additional copies of NRC Form 366A) (17)
FACILITY NAME (1)
Joseph M. Farley Nuclear Plant - Unit 2 Westinghouse evaluated limiting accidents based on the specific flow characteristics of the 2A pump and the most recent as-left flow balance data with the 2A pump operating. These evaluations concluded that even with a 3-minute delay in ECCS flow delivery, use of the realistic ECCS flows demonstrate that the events acceptance criteria continue to be met. Based on this assessment, it can be concluded that if pre-event charging pump performance can be obtained in less than 3 minutes there would be no negative impacts with regard to limiting accidents.
On this basis, it can be concluded that although not desired, some gas accumulation can be tolerated without impacting the pump's ability to perform its safety function. Although during the event on December 4 flow appeared to be recovering, SNC conservatively considered the event to be outside the bounds of acceptability.
Based on the smaller volume of gas detected, engineering judgment was used to conclude that the 2A charging pump was not rendered incapable of performing its intended function during the second event on December 25.
NUMBER.
05000364
Corrective Action
I The A Train HHSI Pump was vented, surveillance testing performed satisfactorily, and the system returned to service.
Applicable Operations procedures have been revised to clearly define the normal VCT pressure control band to minimize gas formation. In addition, criteria to vent the HHSI pumps, if the normal control band is exceeded, has been added.
PAGE (3) 4 OF 4
LER NUMBER (6)
I Operations Plant Staff have been trained on this event.
I YEAR I
Additional Information
The Westinghouse Owners Group (WOG) has an approved project to assess the significance of gas accumulation on the mechanical and hydraulic performance of pumps similar to the HHSI pump design. As a participating member of the WOG, Farley Nuclear Plant will remain cognizant of the project and will consider, as appropriate, all conclusions and/or recommendations.
2005 001 00 SEQUENTIAL NUMBER I
The following LER's have been submitted in the last two years due to TS violations.
I REVISION NUMBER LER 2005-001-00 Unit 1 Technical Specification 3.3.2.C Violation due to Solid State Protection System Card Failure Troubleshooting LER 2004-001-00 Unit 2 Technical Specification 3.7.8 Violation due to Operation with One Train of Service Water Inoperable I
LER 2004-002-00 Unit 2 Plant Entered Mode 3 with One Train of Component Cooling Water Inoperable I
LER 2004-003-00 Technical Specification 3.0.4 Violation Due to Turbine Driven Auxiliary Feedwater Pump I Inoverable I
NHL: FVRM 366 (7-2001)