05000455/LER-2016-001, Regarding Manual Reactor Trip Due to Circuit Breaker Failure That Caused Actuation of Feedwater Hammer Prevention System with Automatic Isolation of Feedwater to Two Steam Generators and Low Steam Generator Levels

Regarding Manual Reactor Trip Due to Circuit Breaker Failure That Caused Actuation of Feedwater Hammer Prevention System with Automatic Isolation of Feedwater to Two Steam Generators and Low Steam Generator Levels

ML16347A458
Person / Time
Site:	Byron
Issue date:	12/09/2016
From:	Kanavos M Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
BYRON 2016-0123 LER 16-001-00
Download: ML16347A458 (4)

LER-2016-001, Regarding Manual Reactor Trip Due to Circuit Breaker Failure That Caused Actuation of Feedwater Hammer Prevention System with Automatic Isolation of Feedwater to Two Steam Generators and Low Steam Generator Levels

Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 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)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i)
4552016001R00 - NRC Website

text

Byron Generating Station Exeton Generation 4450 North German Church Rd wwwexeloncorpcom December 9, 2016 LTR:

BYRON 201 6-0123 File:

1.10.0101 (1D.101) 2.07.0100 (5A.108)

United States Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Byron Station, Unit 2 Renewed Facility Operating License No. NPF-66 NRC Docket No. STN 50-455

Subject:

Licensee Event Report (LER) No. 455-2016-001-00, Manual Reactor Trip Due to Circuit Breaker Failure that Caused Actuation of Feedwater Hammer Prevention System with Automatic Isolation of Feedwater to Two Steam Generators and Low Steam Generator Levels Enclosed is Byron Station Licensee Event Report (LER) No. 455-2016-001-00 regarding loss of power to the Feedwater Hammer Prevention System that resulted in automatic isolation of Feedwater to steam generators and manual reactor trip. This condition is being submitted in accordance with 10 CFR 50.73, Licensee Event Report System.

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 (815) 406-2800.

Respectfully, Mark E. Kanavos Site Vice President Byron Generating Station MEKJGC/sg

Enclosure:

LER 455-20 1 6-00 1 -00 cc:

Regional Administrator NRC Region Ill NRC Senior Resident Inspector Byron Generating Station

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 10131/2018 (06-2016)

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 />.

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Reported lessons learned are irmorporated into the licensing process and led back to Industry.

LICENSEE EVENT REPORT (LER)

Send crrmmentn re riting burden estimate to the FOIA. Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, WasNngton, DC 20555-0001. or by e-mail (See Page 2 for iequired number of digits/characters for each block)

Lo lntocollecls Resource@nrc.gov, end to the Desk Officer, Office of Informehon and RegUatoiy Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington DC 20503. It a (See NUREG-1022, R.3 for instwction and guidance for completing this form means used to impose an intorrnahon collection does not cisplay a Currently vahd 0MB control http://www.nrc.ciov/readinq-rm/doc-collectionslnurecislstaff/srl 022r31) number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.

J 3. PAGE Byron Station Unit 2 05000455 1

OF 3

4. 11TLE Manual Reactor Trip due to Circuit Breaker Failure that Caused Actuation of Feedwater Hammer Prevention System with Automatic Isolation of Feedwater to Two Steam Generators and Low Steam Generator Levels

5. EVENT DATE

6. LER NUMBER

7. REPORT DATE

8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEAL MONTH DAY YEAR FAmLrrs NAME N/A NUMBER 10 12 2016 2016 001 00 12 09 2016 FAmLITY NAME N/A NUMBER

9. OPERATING MODE

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

Li 20.2201(b)

Li 202203(a)(3)(i)

Li 5073(a)(2)(ii)(A)

Li 50.73(a)(2)(viii)(A)

Li 202201(d)

Li 202203(a)(3)(ii)

Li 50.73(a)(2)(ii)(B)

Li 50.73(a)(2)(viii)(B)

Li 20.2203(a)(1)

Li 20.2203(a)(4)

Li 5073(a)(2)(iii)

Li 50.73(a)(2)(ix)(A)

Li 20.2203(a)(2)(i)

Li 50.36(o)(1)(i)(A) 50.73(a)(2)(iv)(A)

Li 50.73(a)(2)(x)

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

Li 50.36(c)(1)(ii)(A)

Li 5073(a)(2)(v)(A)

Li 73.71(a)(4)

C] 20.2203(a)(2)(iii)

Li 50.36(c)(2)

C] 50.73(a)(2)(v)(B)

Li 73.71(a)(5)

Li 20.2203(a)(2)(iv)

Li 50.46(a)(3)(ii)

Li 50.73(a)(2)(v)(C)

Li 73.77(a)(1) 90%

Li 20.2203(a)(2)(v)

Li 50.73(a)(2)(i)(A)

Li 50.73(a)(2)(v)(D)

Li 73.77(a)(2)(i)

Li 20.2203(a)(2)(vi)

Li 50.73(a)(2)(i)(B)

LI 50.73(a)(2)(vii)

C] 7377(a)(2)(ii)

Li 50.73(a)(2)(i)(C)

Li OTHER Spectfy in Abstra5 bolow or in

C. Cause of Event

The analysis and troubleshooting concluded that the apparent cause was due to a manufacturing defect on the Amptector (Westinghouse Amptector hA Serial #000753) circuit board. Laboratory testing was able to identify that the amptector was the cause of the unit trip, and subsequently was able to identify the exact cause of the unit trip down to the component by replacing the diode. A combination of failure analysis reports concluded that there was an issue with the suspect reading with Diode (D30), Resistor R22, and the transistor (Q20). The 3 subcomponents share the same solder joint.

D. Safety Consequences

There were no safety consequences to this event. The plant operated as designed in this case, with the loss of power causing the WHPS to close the FW lso!ation Valves. The unexpected trip of the circuit breaker was a Maintenance Rule Functional Failure. As the circuit breaker is non-safety related, it is not a Safety System Functional Failure.

E. Corrective Actions

Immediate Actions Completed 1.

Performed change out of the feed breaker to MCC 234V4.

2.

Performed a prompt investigation in accordance with Exelon Corrective Action Program procedures.

Corrective Actions Planned 1.

Revise refurbishment testing requirements for the feed breaker to MCC 234V4 tripped to include steps to verify that the breaker will not trip 75%, 50%, and 25% below the setpoint. Also, during scheduled breaker refurbishment preventive maintenance, cycle Amptector hAs out for a replacement.

2.

Perform modifications in subsequent refuel outages to the FW Water Hammer Prevention System to address power supply single point vulnerability.

F. Previous Occurrences

There have been no previous Licensee Event Reports at Byron Station on this issue.

G. Component Failure Data

Manufacturer Nomenclature Model Mfg. Part Number Westinghouse CIRCUIT BREAKER DS-206-MO S/N 02YN025B4-S Page ot