05000298/LER-2016-002, Regarding De-Energized High Pressure Coolant Injection Auxiliary Lube Oil Pump Caused by Light Bulb Failure Results in Loss of Safety Function
| ML16190A112 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 06/27/2016 |
| From: | Limpias O Nebraska Public Power District (NPPD) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NLS2016037 LER 16-002-00 | |
| Download: ML16190A112 (5) | |
| 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)(ii) 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) |
| 2982016002R00 - NRC Website | |
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Nebraska Public Power District Always there when you need us NLS2016037 June 27, 2016 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001
Subject:
Licensee Event Report No. 2016-002-00 Cooper Nuclear Station, Docket No. 50-298, DPR-46
Dear Sir or Madam:
- The purpose of this correspondence is to forward Licensee Event Report 2016-002-00.
There are no new commitments contained in this letter.
s Vice President Nuclear-
. Chief Nuclear Officer
/dv Attachment: Licensee Event Report 2016-002-00 cc:
Regional Administrator w/attachment USNRC - Region IV NPG Distribution w/attachment Cooper Project Manager w/attachment INPO Records Center w/attachment USNRC - NRR Plant Licensing Branch IV-2 via ICES entry Senior Resident Inspector w/attachment USNRC-CNS SRAB Administrator w/attachment SORC Chairman w/attachment.
CNS Records w/attachment COOPER NUCLEAR STATION P.O. Box 98 I Brownville, NE 68321-0098 Telephone: (402) 825-3811 /Fax: (402) 825-5211 www.nppd.com
- NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES:
(11-2015) 10/31/2018
...... -...~
, the NRG may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Cooper Nuclear Station 05000298 1of4
- 4. TITLE De-Energized High Pressure Coolant Injection Auxiliary Lube Oil Pump Caused By Light Bulb Failure Results in Loss of Safety Function
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED YEAR ISEQUENTIALI REV FACILITY NAME DOCKET MONTH DAY YEAR NO.
MONTH DAY YEAR 05000 NUMBER FACILITY NAME DOCKET 04 26 2016 2016 -
002 -
00 06 27 2016 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: {Check all that apply) 0 20.2201(b) 0 20.2203(a)(3)(i) 0 50. 73(a)(2)(ii)(A) 0 50.73(a)(2)(viii)(A) 1 0 20.2201(d) 0 20.2203(a)(3)(ii) 0 50.73(a)(2)(ii)(B) 0 50.73(a)(2)(viii)(B) 0 20.2203(a)(1) 0 20.2203(a)(4) 0 50.73(a)(2)(ii) 0- 5o:73(a)(2)(ix)(A) 0 20.2203(a)(2)(i) 0 50.36(c)(1)(i)(A) 0 50. 73(a)(2)(iv)(A) 0 50. 73(a)(2)(x) 0 20.2203(a)(2)(ii) 0 50.36(c)(1)(ii)(A) 0 50. 73(a)(2)(v)(A) 0 73.71(a)(4)
- 10. POWERLEVEL 0 20.2203(a)(2)(iii) 0 50.36(c)(2) 0 50. 73(a)(2)(v)(B) 0 73.71(a)(5) 0 20.2203(a)(2)(iv) 0 50.46(a)(3)(ii) 0 50.73(a)(2)(v)(C) 0 73.77{a)(1) 100 0 20.2203{a)(2)(v) 0 50.73(a)(2)(i)(A)
~ 50.73(a)(2)(v)(D) 0 73.77(a)(2)(i) 0 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B) 0 50.73(a)(2)(vii) 0 73.77(a)(2)(ii) 0 50.73(a)(2)(i)(C) 0 OTHER Specify in Abstract below or in SEQUENTIAL NUMBER
- - 002 REV NO.
- - 00 Investigation found the 125 volts direct current (VDC) fuse open circuited and the local indication green light and socket were damaged. The green bulb and socket were replaced as well as the red bulb. The 125 VDC fuses were also replaced. The HPCI system was restored to operable status on April 28, 2016, at 1245 CDT after post work testing had been satisfactorily completed.
Examination of the local green indication bulb and socket, and a review of the circuit schematic found that the light did not have a dropping resistor. In this circuit, a dropping resistor helps prevent the fuse in the HPCI ALOP control circuit from opening by limiting current in the indication bulb side of the circuit if a short circuit in the bulb were to occur.
The original HPCI starter circuit utilized a local indication light with a dropping resistor. The cir.cuit was modified in 1984 by the vendor to accommodate environmental requirements. A direct voltage light and socket were substituted for the dropping resistor and light combination. Consequently, if the indication light were to short it would open circuit the 125 VDC portion of the starter circuit. The commercial grade bulb that failed was a 3 watt bulb with a 120MB base style.
BASIS FOR REPORT The HPCI System is a single train safety system. This condition is reportable in accordance with 10 CFR 50. 73(a)(2)(v) as "any event or condition that could have prevented the fulfillment of the safety function of structures or systems that are needed to... (D) Mitigate the consequences of an ~~cident."
The event was reported as Event Notification 51886.
SAFETY SIGNIFICANCE
This is a Safety System Functional Failure. There were no actual safety consequences associated with this event. The potential safety consequences of this event were minimal due to the limited duration the condition existed and the redundant/diverse core cooling systems which remained operable. The HPCI ALOP performance had been previously tested satisfactory at 1312 CDT on the day of the failure. The HPCI system is an emergency core cooling system designed to inject water into the reactor vessel to provide core cooling. The total duration of inoperability, including the time prior to discovery of the condition was less than the 14 day Technical Specification Completion Time. During the time period of inoperability, other core cooling systems (Automatic Depressurization System, Core Spray, and Low Pressure Coolant Injection) were operable and would have adequately responded to a design basis event. The Reactor Core Isolation Cooling system was also operable during this event.
CAUSE
A lack of engineering knowledge led to a design change in 1984 in the HPCI ALOP starter circuitry that diminished the robustness of the circuit with respect to a specific failure modality; direct short circuiting within the indication bulb itself.
NRC FORM 366 (11-2015)
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CORRECTIVE ACTIONS
YEAR 2016 SEQUENTIAL NUMBER
- - 002 REV NO.
- - 00 Develop and implement training to the engineering population with respect to this failure modality. The training will be given to the engineering population in the next available Engineering Support Program training sessions, and will be incorporated into initial training for new-hire engineers.
PREVIOUS EVENTS LER 2016-001 On April 25, 2016, HPCI was declared inoperable due to a failure of the HPCI ALOP.
An electrical relay in the starter circuit prematurely failed after only 133 hours0.00154 days <br />0.0369 hours <br />2.199074e-4 weeks <br />5.06065e-5 months <br /> of operation.
LER 2013-001 A review of industry operating experience identified a susceptibility for unfused remote Direct Current Ammeter Circuits causing a secondary fire due to multiple fire induced faults.
NRC FORM 366 (11-2015)