05000247/LER-2005-002, Regarding Technical Specification Prohibited Condition Due to Exceeding the Allowed Completion Time for One Inoperable Train of ECCS Caused by Gas Intrusion from a Leaking Check Valve
| ML051180141 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 04/14/2005 |
| From: | Dacimo F Entergy Nuclear Northeast |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-05-049 LER 05-002-00 | |
| Download: ML051180141 (7) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2472005002R00 - NRC Website | |
text
Entergy Nuclear Northeast Indian Point Energy Center 450 Broadway, GSB P.O. Box 249 Eny Buchanan, NY 10511-0249 Tel 914 734 6700 Fred Dacimo Site Vice President Administration April 14, 2005 Indian Point Unit No. 2 Docket Nos. 50-247 NL-05-049 Document Control Desk U.S. Nuclear Regulatory Commission Mail Stop O-P1-17 Washington, DC 20555-0001
Subject:
Licensee Event Report # 2005-002-00, "Technical Specification Prohibited Condition Due to Exceeding the Allowed Completion Time for One Inoperable Train of ECCS Caused by an Inoperable Safety Injection Pump".
Dear Sir:
The attached Licensee Event Report (LER) 2005-002-00 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)(i)(B) for an event recorded in the Entergy corrective action process as Condition Report CR-IP2-2005-00370.
There are no commitments made by the Licensee in the attached LER. 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.
Sincerely, Fred R. Dacimo Site Vice President Indian Point Energy Center
Docket No. 50-247 NL-05-049 Page 2 of 2 Attachment: LER-2005-001-00 cc:
Mr. Samuel J. Collins Regional Administrator - Region I U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia, PA 19406-1415 Resident Inspector's Office U.S. Nuclear Regulatory Commission Indian Point Unit 2 P.O. Box 59 Buchanan, NY 10511-0059 Mr. Paul Eddy State of New York Public Service Commission 3 Empire Plaza Albany, NY 12223-1350 INPO Record Center 700 Galleria Parkway Atlanta, Georga 30339-5957
Abstract
On February 18, 2005 engineering determined that the amount of gas vented from the 23 Safety Injection Pump on January 27, 2005 was of such a quantity that the pump was inoperable. Prior to this event the station was dealing with SI accumulator out-leakage.
The accumulator leakage was found to be migrating back to the Refueling Water Storage Tank through a circuitous path. As the accumulator has a nitrogen overpressure system normally in service there existed the potential for entrainment and subsequent dissolution of gas.
As events unfolded some of the dissolution of gas resulted in gaseous void areas accumulating within the 23 Safety Injection pump casing. The cause of the event was back-leakage of accumulator water through the Safety Injection System and subsequent gas dissolution within the Safety Injection Pump casing. Corrective actions included venting the applicable portions of the system piping and components to ensure operability. A design change has been generated to install an additional test line isolation valve to prevent accumulator backleakage. In addition, venting/ultrasonic test monitoring is ongoing. The event had no effect on public health and safety.
NRC FORM 366 (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)
Per calculation IP-CALC-05-00059 Rev. 1, the volume of gas (at system pressure of 23.8 psig) vented from the 23 SI pump casing was calculated to be 2.87 cubic feet. Since the 23 SI pump was operated satisfactorily on 12/24/04 during its quarterly surveillance test without any degraded head or adverse vibration it is reasonable to state that the pump was operable from 11/21/04 (start date of system leakage past 839H) thru the 12/24/04 surveillance test. Subsequent to 12/24/04 gas built up in the pump casing and at some point reached an amount that challenged pump operability. Since the period of time is not known with certainty the time for pump inoperability will be taken as T/2 where T is 34 days(time-frame between 12/24/04 and 01/27/05). Therefore the pump was inoperable for 17 days.
PAST SIMILAR EVENTS A review of the past two years of Licensee Event Reports (LERs) for events that involved inoperable components that exceeded the TS allowed completion time identified two issues when AOTs were exceeded. LER 2003-002 described an event where a boric acid transfer pump flow path could not be verified due to an improperly installed diaphragm valve. LER 2005-001 described an event where an auxiliary component cooling water pump was determined to be inoperable due to an improperly serviced discharge check valve. However, there are distinctly different causes for these events. The corrective actions associated with these events would not have prevented this particular event from occurring.
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 the SI or ECCS.
There were no significant potential safety consequences of this event under reasonable and credible alternative conditions. A risk evaluation determined that the incremental Core Damage Probability is 7.92E-9 and the incremental Large Early Release Probability is 1.95E-9 for the 17 day inoperability period indicating there was no significant risk to public health and safety. This evaluation is based on only 23 SI pump being adversely affected by the gas intrusion into the SI system. It is noted that past operability evaluations for 21/22 SI pumps are ongoing and that the risk evaluation for this LER assumes availability of these two pumps.
.NRC FORM 366A(1.2001)