05000454/LER-2015-003, Re One Train of Diesel Generator System Inoperable Longer than Allowed by Technical Specifications Due to Loss of Diesel Fuel Oil System Volume

Re One Train of Diesel Generator System Inoperable Longer than Allowed by Technical Specifications Due to Loss of Diesel Fuel Oil System Volume

ML15208A056
Person / Time
Site:	Byron
Issue date:	07/27/2015
From:	Kearney F Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BYRON 2015-0087 LER 15-003-00
Download: ML15208A056 (4)

LER-2015-003, Re One Train of Diesel Generator System Inoperable Longer than Allowed by Technical Specifications Due to Loss of Diesel Fuel Oil System Volume

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(ii) 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2) 10 CFR 50.73(a)(2)(ix)(A) 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
4542015003R00 - NRC Website

text

Byron Generating Station Exeton Generation 4450 North German Church Rd Byron, IL 61010-9794 July 27, 2015 LTR:

BYRON 2015-0087 File:

1.10.0101 (JD.101) 2.07.07 00 (5A.108)

United States Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Unit 1 Facility Operating License No. NPF-37 NRC Docket No. STN 50-454 www.exeloncorp.com Sublect:

Licensee Event Report (LER) 454-2015-003-00, Byron Unit 1, One Train of the Diesel Generator System Inoperable Longer Than Allowed by Technical Specifications Due to Loss of Diesel Fuel Oil System Volume Enclosed is Byron Station Licensee Event Report (LER) No. 454-2015-003-00 regarding occurrence in the prior three years when the Unit 1, B-train Diesel Generator was determined to have been inoperable for a period not allowed by technical specifications due to loss of Diesel Fuel Oil System Inventory. This condition is reportable in accordance with 70 CFR 50.73(a)(2)(i)(B) for any event or condition that is prohibited by Technical Specifications.

There are no regulatory commitments in this report.

Should you have any questions concerning this submittal, please contact Mr. Douglas Spitzer, Regulatory Assurance Manager, at (875) 406-2800.

FAK/GC/sg

Enclosure:

LER 454-20 1 5-003-00 cc:

Regional Administrator NRC Region Ill NRC Senior Resident Inspector Byron Generating Station Respecifully, Site Vice President Byron Generating Station

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 07131/2077 102-2014)

Estimated burden per response to comply with this mandatory collection request: 80 hours9.259259e-4 days <br />0.0222 hours <br />1.322751e-4 weeks <br />3.044e-5 months <br />.

c.f Reported lessons learned are incorporated into the licensing process and fed back to industry, I

Send comments regarding burden estimate to the FOIA, Pivacy and tntormation Coltections S

/

Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by

internet e-mail to lnfocottects.Resource@nrc.gov, and to the Desk Officer, Office ot Inturmation and (See Page 2 for required number of RegulatoryAffairs, NEOB-10202, 3150-0104), Office ot Management and Budget, Washington, DC

,4 4

/

I,

+

I-. ki I

20503. Ifs means used to impose an intormation collection does not display a currently valid 0MB tgi t5t Ci araccers or eac uiOC,.1 control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

3. PAGE Byron Station, Unit 1 05000454 1

OF 3

4. TITLE One Train of the Diesel Generator System Inoperable Longer than Allowed by Technical Specifications Due to Loss of Diesel Fuel Oil System Volume

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR N/A N/A FACILITY NAME DOCKET NUMBER 10 22 2014 2015 003 00 07 27 2015 N/A N/A

9. OPERATING MODE

71. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 70 CFR §: (Check all that apply)

LI 20.2201(b)

LI 20.22O3(a)(3)(i)

LI 5O.73(a)(2)(i)(C)

LI 5O.73(a)(2)(vii)

LI 20.2201(d)

LI 2O.2203(a)(3)ti)

LI 50.73(a)(2)(ii)fA)

LI 50.73(a)(2)(viii)(A)

LI 20.2203(a)(1)

LI 20.22O3(a)(4)

LI 50.73(a)(2)(ii)(e)

LI 5O.73(a)f2)(viii)(B)

LI 20.2203(a)(2)(i)

LI 50.36(c)(1)(i)(A)

LI 50.73(a)(2)fiii)

LI 50.73(a)(2)(ix)(A)

10. POWER LEVEL LI 20.2203(a)(2)(ii)

LI 50.36(c)(1)(ii)(A)

LI 50.73(a)(2)Ov)(A)

LI 50.73(a)(2)(x)

LI 2O.2203(a)(2)(iii)

LI 50.36(c)(2)

LI 50.73(a)(2)(v)(A) 73.71 (a)(4) 100 LI 20.2203(a)(2)(iv)

LI 5O.46(a)(3)Qi)

LI 50.73(a)(2)(v)(B)

LI 73.71(a)(5)

LI 20.2203(a)(2)(v)

LI 50.73(a)(2)(i)(A)

LI 50.73(a)(2)(v)(C)

LI OTHER LI 20.2203(a)(2)(vi) 50.73(a)(2)(i)(B) 50.73(a)(2)(v)(D)

Specify or Abstract below or in

12. LICENSEE CONTACT FOR THIS LER ICENSEE CONTACT TELEPHONE NUMBER (Include Area Code)

Douglas Spitzer Manager, Byron Regulatory Assurance (815) 406-2800CAUSE SYSTEM COMPONENT FACTURER REPORTABLE

CAUSE

X DC V

Anchor Y

N/A Darlina

14. SUPPLEMENTAL REPORT EXPECTED LI YES (If yes, complete 15. EXPECTED SUBMISSION DATE)

NO ABSTRACT (Limit to 7400 spaces, i.e., approximately 75 single-spaced typewritten lines)

On November20, 2014 at 1248 hours0.0144 days <br />0.347 hours <br />0.00206 weeks <br />4.74864e-4 months <br />, the Byron Station Main Control Room (MCR) received an alarm identifying that fuel oil level was low on one of two Diesel Oil Storage Tanks (DOSTs) associated with the Unit 1, B-train (1 B)

Emergency Diesel Generator fDG). At 1328 hours0.0154 days <br />0.369 hours <br />0.0022 weeks <br />5.05304e-4 months <br />, the MCR received an alarm identifying level was also low in the second DOST associated with the 1 B DG. Operators determined that the low level condition was due to leakage to the Unit 1, A-train (1 A) fuel oil storage system through one of two 1 A DOST inlet valves. The Corrective Action Program investigation identified that leakage initially occurred during the 1 B DG monthly surveillance conducted on October 22, 2014.

Subsequent analysis concluded that the loss of inventory from the 1 B DOSTs to the 1 A DOSTs would result in the 1 B DG not meeting its design mission time without operator intervention.

This event is reportable in accordance with 10 CFR 50.73(a)f2)(i)(B) for an operation or condition prohibited by Technical Specifications.

The cause of the event was a degraded DOST inlet valve that allowed fuel to transfer from the 1 B DOSTs to the 1A DOSTs.

NRC FORM 366 (02-2014)

IRC =

A.

Plant Condition Prior to Event Event Date/Time: October 22, 2014/ 1428 hours0.0165 days <br />0.397 hours <br />0.00236 weeks <br />5.43354e-4 months <br /> CST Unit 1

- Mode 1

- Power 100 percent Reactor Coolant System {ABJ: Normal operating temperature and pressure.

B.

Description of Event

On November 20, 2014 at 1248 hours0.0144 days <br />0.347 hours <br />0.00206 weeks <br />4.74864e-4 months <br />, the Byron Station Main Control Room (MCR) received an alarm identifying that fuel oil level was low on one of two Diesel Oil Storage Tanks (DOSTs) associated with the Unit 1, B-train (1 B) Emergency Diesel Generator (DG). At 1328 hours0.0154 days <br />0.369 hours <br />0.0022 weeks <br />5.05304e-4 months <br />, the MCR received an alarm identifying level was also low in the second DOST associated with the 1 B DG. Operators determined that the low level condition was due to leakage to the Unit 1, A-train (1 A) fuel oil storage system through one of two 1 A DOST inlet valves. This meant that diesel fuel oil was being transferred from the 1 B DOSTs to the 1 A DOSTs. Operators identified leak-by through the normally closed 1A DG DOST inlet valve (1 D0001 C). The valve was immediately cycled in order to re-seat the valve. The valve was verified to be closed and the overflow was stopped.

On December 22, 2014 at 1351 hours0.0156 days <br />0.375 hours <br />0.00223 weeks <br />5.140555e-4 months <br />, the same overflow condition occurred for a second time at the same inlet valve.

This condition prompted Engineering to determine if the 1 B DOSTs would be able to supply enough fuel to the 1 B DG for the required design basis mission time of seven days. The analysis concluded that the loss of volume from the 1 B DOSTs to the 1 A DOSTs would result in the 1 B DG not meeting its design mission time without Operator intervention.

Th Corrective Action Program investigation identified that leakage initially occurred during the 1 B DG monthly surveillance conducted on October 22, 2014.

Two periods of time were identified during which the 1 B DG was determined to be previously inoperable. They occurred as follows: October 22, 2014 through November 20, 2014 (29 days), and December 10, 2014 through December 22, 2014 (12 days).

The 1A DG was operable and available at all times.

Byron TS 3.8.3, Diesel Fuel Oil, Condition A requires each DG have a storage volume of at least 44,000 gallons of fuel. The Byron TS Bases B 3.8.3 states that the stored diesel fuel oil is required to have sufficient supply for seven days of post-accident load operation. Although the station was still in compliance with TS 3.8.3, Condition A (i.e., diesel fuel oil volume never dropped below 44,000 gallons) when it was determined the 1 B DG could not meet its required mission time, the DG would have been considered inoperable in accordance with TS 3.8.3, Condition D, One or more DGs with diesel fuel oil not within limits for reasons other than Condition A, B, or C.

Condition D requires the associated DG to be declared inoperable immediately. Byron TS 3.8.1, AC Sources

Operating, Condition B One required DG inoperable, provides for an allowed completion time of 14 days to restore the respective DG. The 14 day allowed outage time for TS 3.8.1, Condition B was exceeded during the 29 day period that the 1 B DG was inoperable. This condition is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) for an operation or condition prohibited by Technical Specifications.

Byron Operations subsequently performed a review of opposite train equipment status during the time periods identified to determine whether a Loss of Safety Function occurred. This review identified two instances where the 1 A Containment Spray Train (CS) was inoperable for greater than 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> during the time that the 1 B DG would not have been able to meet its mission time.

December 11, 2014 Entered LCD at 7224 hours0.0836 days <br />2.007 hours <br />0.0119 weeks <br />0.00275 months <br /> and exited LCD at 1639 hours0.019 days <br />0.455 hours <br />0.00271 weeks <br />6.236395e-4 months <br />, December 18, 2014 Entered LCD at 0117 hours0.00135 days <br />0.0325 hours <br />1.934524e-4 weeks <br />4.45185e-5 months <br /> and exited LCD at 1433 hours0.0166 days <br />0.398 hours <br />0.00237 weeks <br />5.452565e-4 months <br />.

This condition is reportable via a 60 day LER in accordance with 10 CFR 50.73(a)(2)(v)(D) for an event or condition that could have prevented the fulfillment of a safety function of structures or systems that are needed to mitigate the consequences of an accident.

C. Cause of Event

The cause of the event was leak-by from the 1 DDOO1 C inlet valve that allowed fuel to transfer from the B-train tanks to the A-train tanks.

The cause for the DOST inlet valve (1 D0001 C) leaking is under investigation, and the valve has not been repaired or replaced. This condition is acceptable until the inlet valve is replaced, as the mitigating action to close inline manual valve, 1 DDO55B, has stopped all loss of fuel oil inventory. Leaking inlet valve 1 DDOO1 C will be repaired under Byron Work Drder 01796243.

This event has been thoroughly reviewed under an Equipment Apparent Cause Evaluation in the Byron Corrective Action Program. (Reference Byron Issue Report 2506852).

D. Safety Significance

This event is not considered risk significant. The results of the PRA risk review of this event indicate that the 1 B DG was available based on the large volume of fuel oil still available, even though it would have been inoperable in accordance with TS 3.8.3, Condition D. The PRA risk review also indicates that the short period that the CS pumps were declared inoperable is not risk significant as modelled in the Byron PRA. The 1A DG was operable and available at all times.

E.

Corrective Actions

Apparent Cause

- Leaking inlet valve 1 D0001 C will be repaired under Byron Work Drder 01796243.

F.

Previous Dccurrences There have been no other occurrences of this nature in the previous three years.