05000457/LER-2010-001, Regarding Essential Service Water Pump 2A Braided Hose Failure Resulted in a Condition Prohibited by Technical Specifications

Regarding Essential Service Water Pump 2A Braided Hose Failure Resulted in a Condition Prohibited by Technical Specifications

ML101060567
Person / Time
Site:	Braidwood
Issue date:	04/16/2010
From:	Shahkarami A Exelon Generation Co, Exelon Nuclear
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BW100043 LER 10-001-00
Download: ML101060567 (4)

LER-2010-001, Regarding Essential Service Water Pump 2A Braided Hose Failure Resulted in a Condition Prohibited by Technical Specifications

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(x)
4572010001R00 - NRC Website

text

10 CFR 50.73 April 16,2010 BW100043 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Unit 2 Facility Operating License No. NPF-77 NRC Docket No. STN 50-457

Subject:

Licensee Event Report 2010-001-00 -- Essential Service Water Pump Inoperability Due to Braided Hose Leakage The enclosed Licensee Event Report (LER) is being submitted in accordance with 10 CFR 50.73, "Licensee event report system," paragraph (a)(2)(i)(B), as a condition prohibited by technical specifications. This condition was identified on February 15, 2010, and involved leakage on a braided hose, which provides seal cooling to the 2A essential service water pump inboard seal.

10 CFR 50.73(a) requires an LER to be submitted within 60 days following discovery of the event.

Therefore, this report is being submitted by April 16, 2010.

There are no regulatory commitments contained in this letter. Should you have any questions concerning this submittal, please contact Mr. Ronald Gaston, Regulatory Assurance Manager, at (815) 417-2800.

Respectfully, Amir Shahkarami Site Vice President Braidwood Station

Enclosure:

LER 2010-001-00 cc: NRR Project Manager -- Braidwood Station Illinois Emergency Management Agency -- Division of Nuclear Safety US NRC Regional Administrator, Region III US NRC Senior Resident Inspector (Braidwood Station)

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150*0104 EXPIRES 011/31/2010 LICENSEE EVENT REPORT (LER) reverse for reqUired number of digits/characters for each block)

1. FACILITY NAME Braidwood Station, Unit 2

4. TITLE

!"",'u:>nti~1 Service Water Pump 2A Braided Hose Failure Resulted in a Condition Prohibited by Technical Specifications OTHER FACILITIES INVOLVED

5. EVENT DATE

7. REPORT DATE REV FACILITY MONTH DAY YEAR YEAR NO.

MONTH DAY YEAR FACILITY NAME 02 15 2010 2010 001 00 04 16 2010 N/A N/A N/A DOCKET NUMBER N/A

9. OPERATING MODE

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check al/ that apply) 1 50.73(a)(2)(vII) o 50.73(a)(2)(viii)(A) 50.73(a)(2)(vlii)(B) o 50.73(a)(2)(ix)(A) 50.73(a)(2)(x) 73.71(a)(4) 73.71(a)(5)

OTHER Specify in Abstract below or In =

2. DOCKET 05000457 YEAR 2010

6. LER NUMBER I

NUMBER' I 001 REV NO, 00 2

3. PAGE OF 3

Background:

~.

Plant Operating Conditions Before The Event

Event Date:

Unit: 2 February 15, 2010 MODE: 1 Event Time: 1443 CST Reactor Power: 100 percent Unit 2 Essential Service Water:

13.

Description of Event

Normal operating temperature and pressure On January 29, 2010, an equipment operator observed leakage from a braided hose that runs from the casing of the 2A SX pump to its inboard seal. The hose provides coolin9 and flushing functions to the pump seal. The initial report indicated the leak rate was sixty drops per minute from a fitting. The size of the leak did not prevent the 2A SX pump from delivering required flow to safety related loads. Additionally, the leak was not affecting any components on the 2A Essential Service Water (SX) [BI] pump or any other equipment in the area. Because the initial inspection indicated the leak was from a fitting, it was not considered pressure boundary leakage, and the pump was determined to be operable in the prompt operability determination. Technical Specifications (TS)

Limiting Condition Operation 3.7.8 Condition A for the 2A SX pump was not entered.

On February 2, 2010, the 2A SX pump was run so that Plant and Design Engineering could perform an inspection of the flexible hose while the pump was running and while it was idle. Zero leakage was observed during this inspection. However, it was conservatively decided to proceed with replacement of the hose during a 2A SX strainer work window that commenced later on February 2, 2010. It was also decided that the flexible hose would be submitted for failure analysis after removal.

The flexible hose was replaced during the work window and sent to a vendor for failure analysis. The work window was exited on February 4, 2010, and the 2A SX train was declared operable.

On February 15, 2010, the station was provided the failure analysis results, which concluded the hose contained a pinhole leak approximately seven inches from one end of the hose. The leak was caused by external wear from rubbing contact with the braided wire jacket. Similar non-through wall wear was observed at several other locations along the length of the hose. The hose's application makes it susceptible to vibration-induced movements that promote wear.

The failure d"d'y;:>';:> results represent pressure boundary leakage of an ASME Section III Class 3 code line. As such, the pump should have been declared inoperable at the time the leak was identified (January 29, 2010) until the pump was restored to operable status following the 2A SX strainer work window (February 2,2010). The amount of time would have exceeded the allowed outage time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> and resulted in a condition not allowed by TS. The event is being reported pursuant to 50.73(a)(2)(I)(B), as a condition prohibited by TS 3.7.8 Condition C.

The pressure boundary leakage was discovered upon receipt of the failure analysis results (February 15, 2010).

No additional structures, "'y;:>'" ";:>, or components were inoperable at the start of this event that contributed to the event.

NRC FORM PRINTED ON RECYCLED PAPER

C.

Cause of Event

LICENSEE EVENT REPORT (LER) u.s. NUCLEAR REGULATORY COMMISSION CONTINUATION SHEET

2. DOCKET

6. LER NUMBER

3. PAGE I "'''''''''TIA I

REV 05000457 YEAR NUMBER NO.

3 OF 3

2010 001 00 The failure analysis concluded the following: Pressure testing indicated the flex hose contained a pinhole leak approximately seven inches from one end of the hose. The leak was caused by external wear from rubbing contact with the braided wire jacket. Similar non-through wall wear was observed at several other locations along the length of the hose. The hose's application makes it susceptible to vibration-induced movements that promote wear.

p.

Safety Consequence$:

The line provides seal flushing and cooling functions. The required flow through the line must circulate around the primary ring (seal face) through a mating ring (seat) at no less than 0.4 gallons per minute (gpm) in order to remove heat generated, or failure may occur. Based on a review of the failure analysis report and engineering judgment, the flex hose would have supported operation of the pump. The through-wall flaw was the result of fretting of the inner bellows by the outside stainiess steel braiding and was localized. Based on the localized nature of the degradation mechanism and the robustness of the flexible hose design when compared to actual operating conditions, the degraded condition would not have resulted in a catastrophic failure of the hose. As a result, the increase in plant risk was minimal.

There were no actual safety consequences to this condition.

~.

Corrective Actions

The corrective actions include:

The braided hose has been replaced.

A cushioning bronze inner braid on the SX seal water flexible hoses will be installed (i.e., flexible hose that is supplied with a bronze braid between an inner hose and an outer stainless steel braided jacket).

A 6-year replacement preventive maintenance program (PM) will be implemented for the SX seal water flexible hoses. The 6-year frequency was chosen based upon the time from installation to the experienced failure (approximately eight years).

Operator training will be provided, related to ASME code applicability and system design and on short term LeO actions requiring assistance from other groups.

Previous Occurrences

There have been no previous, similar events identified at the Braidwood Station.

G

Component Failure Data

Mam Senior Flexonics Inc.Flexible Hose Assembly Model J43350-6 Mfg. Part Number

%" x 42"-J43350-6 PRINTED ON RECYCLED PAPER