05000321/LER-2010-004, Regarding Emergency Diesel Generator La Excess Fuel Oil Return Tubing Failure

Regarding Emergency Diesel Generator La Excess Fuel Oil Return Tubing Failure

ML102140164
Person / Time
Site:	Hatch
Issue date:	07/30/2010
From:	Madison D Southern Nuclear Operating Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
LER 10-004-00
Download: ML102140164 (7)

LER-2010-004, Regarding Emergency Diesel Generator La Excess Fuel Oil Return Tubing Failure

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)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function
3212010004R00 - NRC Website

text

Dennis R. Madison Southern Nuclear Vice President - Hatch Operating Company, Inc.

Plant Edwin I. Hatch 11028 Hatch Parkway North Baxley, Georgia 31513 Tel 912.537.5859 Fax 912.3662077 SOUTHERN'\\

COMPANY July 30, 2010 Docket No.:

50-321 NL-10-1458 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555-0001 Edwin I. Hatch Nuclear Plant Licensee Event Report 2010-004-0 Emergency Diesel Generator 1A Excess Fuel Oil Return Tubing Failure Ladies and Gentlemen:

In accordance with the requirements of 10CFR 50.73(a)(2)(i)(B), Southern Nuclear Operating Company (SNC) hereby submits the enclosed Licensee Event Report which addresses a failure of a section of fuel tubing on an emergency diesel generator.

This letter contains no NRC commitments. If you have any questions, please contact Doug McKinney at (205) 992-5982.

Respectfully submitted,

~~YJ1~

D. R. Madison Vice President - Hatch DRM/WEB/msc Enclosure: LER 2010-004-0

U. S. Nuclear Regulatory Commission Log: NL-10-1458 Page 2 cc: Southern Nuclear Operating Company Mr. J. T. Gasser, Executive Vice President Ms. P. M. Marino, Vice President - Engineering RTYPE: CHA02.004 U. S. Nuclear Regulatory Commission Mr. L. A. Reyes, Regional Administrator Mr. R. E. Martin, NRR Project Manager - Hatch Mr. E.D. Morris, Senior Resident Inspector - Hatch

Edwin I. Hatch Nuclear Plant Emergency Diesel Generator 1A Excess Fuel Oil Return Tubing Failure Licensee Event Report 2010-004-0

X APPROVED BY OMB: NO. 3150-0104 EXPIRES: 08/31/2010 NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION 9-2007)

, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

2. DOCKET NUMBER

13. PAGE

1. FACILITY NAME Edwin 1. Hatch Nuclear Plant Unit 1 05000321 1 OF 4

4. TITLE Emergency Diesel Generator lA Excess Fuel Oil Return Tubing Failure

7. REPORT DATE

8. OTHER FACILITIES INVOLVED FACILITY NAME

5. EVENT DATE

6. LER NUMBER DOCKET NUMBER SEQUENTIAL REV DAY YEAR MONTH DAY YEAR YEAR MONTH NUMBER NO.

FACILITY NAME DOCKET NUMBER

- 004 07 30 2010 03 2010 2010 0

11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)

9. OPERATING MODE o 20.2201 (b) o 20.2203(a)(3)(i) o 50.73(a)(2)(i)(C) o 50.73(a)(2)(vii) o 20.2201 (d) o 20.2203(a)(3)(ii) o 50.73(a)(2)(ii)(A) o 50. 73(a)(2)(viii)(A)

I o 20.2203(a)(1) o 20.2203(a)(4) o 50.73(a)(2)(ii)(B)

[J 50.73(a)(2)(viii)(B) o 20.2203(a)(2)(i) o 50.36(c)(1 )(i)(A) o 50.73(a)(2)(iii)

[] 50.73(a)(2)(ix)(A) o 20.2203(a)(2)(ii) o 50.36(c)(1 )(ii)(A) o 50.73(a)(2)(iv)(A) o 50.73(a)(2)(x)

10. POWER LEVEL o 20.2203(a)(2)(iii) o 50.36(c)(2) o 50.73(a)(2)(v)(A) o 73.71 (a)(4) o 20.2203(a)(2)(iv) o 50.46(a)(3)(ii) o 50.73(a)(2)(v)(B) o 73.71 (a)(5) 99.8 o 20.2203(a)(2)(v) o 50.73(a)(2)(i)(A) o 50.73(a)(2)(v)(C) o OTHER o 20.2203(a)(2)(vi) 181 50.73(a)(2)(i)(B) o 50.73(a)(2)(v)(D)

Specify in Abstract below or in NRC Form 366A

12. LICENSEE CONTACT FOR THIS LER FACILITY NAME I~ELEPHONE NUMBER (Include Area Code)

!Edwin I. Hatch / B. D. McKinney, Regulatory Response Manager (205) 992-5982 MANU REPORTABLE MANU REPORTABLE

CAUSE

SYSTEM COMPONENT

CAUSE

SYSTEM COMPONENT FACTURER TO EPIX FACTURER TO EPIX EK DG FOIO Y

14. SUPPLEMENTAL REPORT EXPECTED

15. EXPECTED MONTH DAY YEAR SUBMISSION o YES (If yes, complete 15. EXPECTED SUBMISSION DATE) 181 NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)

During operation of Emergency Diesel Generator (EDG) IA for monthly surveillance, at 1443 EDT on June 03,2010 with the Unit operating at full power, a section of one-quarter-inch tubing in the fuel oil system became disconnected from its fitting rendering EDGlA inoperable due to the potential for fire. Applicable requirements of the Technical Specifications were accomplished and plant operations continued. The tubing's function is to route waste fuel oil from the injectors to the fuel oil collection tank. The tubing separation occurred at the fitting to a discharge check valve which prevents backflow of waste oil to the injectors. This tubing failure occurred subsequent to an observed small amount of leakage at the same location on April 0 I, 2010. An attempt at that time to stop that leakage by tightening the fitting was unsuccessful. Subsequent to the attempt to stop the leakage, the potential impact on EDG operation was evaluated and judged to be acceptable for EDG operation pending future repair. The apparent cause of both the leakage and subsequent tubing separation was degradation of the tubing connection due to wear and stresses resulting from the repetitive disassembly and re-assembly during scheduled maintenance activities.

Subsequent to both the noted leakage and the tubing separation, the corresponding tubing for the other four EDGs was examined for signs of leakage or cracking. None was found and those EDGs were determined to be operable.

06 PRINTED ON RECYCLED PAPER NRC FORM 366 (9-2007)

(If more space is required, use additional copies ofNRC Form 366A)

PLANT AND SYSTEM IDENTIFICAnON General Electric - Boiling Water Reactor Energy Industry Identification System codes appear in the text as (EllS EK)

DESCRIPTION OF EVENT

On June 03,2010, at approximately 1443 EDT, with Unit 1 operating at 2799 CMWTh, 99.8 percent rated thermal power, a section of one-quarter inch tubing in EDG lA's fuel system separated from the fitting that secured it to a discharge check valve. The discharge of diesel fuel oil from the subject tubing on to the surfaces of the EDG exhaust manifold and into its environs created the potential for unsafe conditions for continued EDG operation, and the EDG IA was secured at approximately 1448 EDT. The EDG had been in operation for planned monthly surveillance at the time of the tubing separation. Based on the information available at the time, it was judged that EDG IA would not be capable of performing its intended safety function for its applicable mission time, and it was declared to be inoperable. Actions required by Technical Specification Limiting Condition for Operation (LCO) 3.8.1 were taken, including the verification of operability of the remaining Unit 1 EDGs.

The subject tubing is one quarter inch in diameter. It functions to direct "waste" diesel fuel oil from the EDG's fuel injectors to a fuel oil collection tank on the EDG skid. In the subject line is a check valve which prevents possible back flow of the fuel oil in the line. The separation of the tubing occurred at the point of connection of the tubing and the outlet side of that check valve. That connection is secured by a typical flared-compression-type fitting of the tubing being attached to the check valve's tapered threaded fitting by a compression nut.

CAUSE OF EVENT

The direct cause of the tubing separation was judged to be degradation of the flared compression-type fitting due to apparent tubing wall thinning likely produced by repeated stressing of the material through repetitive removal and re-assembly of the fitting connecting the failed tubing and the associated check valve as part of planned diesel generator maintenance. The repeated application of the stress from torquing the fitting's compression nut upon re-assembly can thin the material and in some cases can lead to cracking of the tubing wall.

A precursor to the tubing failure was noted on April 01, 2010, when a small amount of leakage from this same portion of tubing was noted. An attempt to stop the leakage by torquing the compression nut of the fitting to the check valve was unsuccessful, and an evaluation of continued operation of the EDG was made. Due to nature of the leak (dripping onto the floor area), the limited leak rate and the fact that the surface onto which the fuel oil was leaking was well below the diesel fuel oil ignition temperature (a margin on the order of 300 degrees Fahrenheit), EDG operation was judged to be operable. A work order for repair of the leakage was initiated but had not been worked prior to the June 3, 2010 event.

REPORTABILITY ANALYSIS AND SAFETY ASSESSMENT This event is reportable under IOCFR 50.73(a)(2)(i)(B), in that an event and an associated condition occurred and existed that was prohibited by the technical specifications. It is reportable since surveillance testing indicated that equipment (e.g., one train of a multiple train system) was not capable of performing its specified safety functions from the time of the discovery of the precursor leak on April 0 I, 2010, and, thus would have been inoperable for a period of time longer than allowed by technical specifications (i.e., the 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> LCO allowed outage time). The June 03,2010 testing was conducted within the required time (i.e., the PRINTED ON RECYCLED PAPER (~2007)

LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET U.S. NUCLEAR REGULATORY COMMISSION

1. FACILITY NAME

2. DOCKET

6. LER NUMBER

3. PAGE Edwin I. Hatch Nuclear Plant Unit 1 05000321 I

SEQUENTIAL IREVISION NUMBER NUMBER YEAR 3

OF 4

2010 004 o

surveillance interval plus any allowed extension), however there was firm evidence, based on a review of relevant information drawn from equipment history and the Condition Reporting system (i.e., CR 2010104391) that the causative condition that resulted in the tubing separation existed previously.

By virtue of the fact that the condition revealed by the April 01, 2010 leak that led to the separation which occurred during the June 03, 2010 surveillance was documented at the time of that discovery, this event meets the reporting criteria for 50.73(a)(2)(i)(B).

This event occurred during routine maintenance I surveillance operation of EDG IA with Unit I at approximately full power with electrical power for the unit's auxiliary loads connected to 4.16-kV buses being supplied from off-site sources through the unit's auxiliary transformers and startup transformers. Thus, the cessation of the operation of EDG IA due to the dispersal of fuel oil from the failed tubing did not result in any plant transient or loss of operating equipment function other than EDG lA itself.

Upon the declaration of the inoperable status of EDG IA due to the perceived risk of fire from the fuel oil released to the environs by the separated tubing, the Technical Specification Limiting Condition for Operation (LCO) 3.8.1 applied and the appropriate Actions (specifically, those Actions required for Condition B - "One Unit I or the swing DG inoperable") were taken.

The design of the plant's electrical power systems and compliance with the associated technical specifications provide assurance of independent and redundant available sources of power to the Engineered Safety Feature (ESF) systems during all anticipated operational occurrences and accident conditions. Thus, the electrical power required to safely shut down the reactor, maintain the shutdown condition, and operate all auxiliaries necessary for plant safety was available throughout this event. Based on this information, this event had low

CORRECTIVE ACTIONS

Short term corrective actions implemented in response to the subject separation of a section of the tubing of the EDG lA fuel oil system were the following.

EDG IA was shutdown to stop the release of diesel fuel oil to the EDG's environs upon discovery of the tubing failure.

EDG IA was declared inoperable and LCO 3.8.1 was entered and applicable Actions for Condition B were taken.

The separated tubing in the diesel fuel oil system of EDG IA was repaired and the EDG returned to available status on June 04, 2010 at 1535 EDST. The EDG was restored to operable status and the associated action statement was cleared at 0130 on June 05,2010.

The corresponding portions of tubing in each of the other four EDGs in the plants electrical power system were inspected and showed no degradation or cracking. There was slight wear noted at the tips of the flares on EDGs IE and IC. As a preemptive measure the applicable tubing on all EDGS was replaced since the subject tubing on all EDGs was of a like design and had experienced a similar service and maintenance history.

PRINTED ON RECYCLED PAPER (9-2007)

LICENSEE EVENT REPORT (LER)

CONTINUATION SHEET U.S. NUCLEAR REGULATORY COMMISSION

1. FACILITY NAME

2. DOCKET

6. LER NUMBER

3. PAGE Edwin I. Hatch Nuclear Plant Unit I 05000321 YEAR I SEQUENTIAL IREVISION NUMBER NUMBER 4

OF 4

2010 004 0

It should be noted that at the time of the April 0 I, 20 I0 observation of a fuel leak on EDG IA noted above, an inspection of the other four EDGs was conducted to verify that there were no evidence of current leakage or residue that would indicate past leakage at the corresponding fuel line connections.

That inspection determined that the leakage noted on EDG IA was unique to that diesel generator.

A cause determination for the failed tubing was initiated and is near its conclusion. Depending of the findings of that cause determination and any associated recommendations, additional longer term corrective or preventative actions may be enacted. If the circumstances or conclusions described herein are significantly revised through the review of that cause determination by staff and management, a supplemental Licensee Event Report will be submitted for the NRC's information and files.

ADDITIONAL INFORMATION

Failed Component Information:

Other Systems Affected: 4.16 kV ESF buses 1E (lost onsite standby power source when EDG IA

. declared inoperable)

EllS System Code: EK EllS Component Code: DG Manufacturer: Fairbanks Morse Model Number: 3800TD Type: one quarter inch diameter steel tubing - skid mounted EDG vendor supplied sub-component Manufacturer Code: FOlD Commitment Information: This report does not create any new permanent licensing commitments

Previous Similar Events

None PRINTED ON RECYCLED PAPER