05000250/LER-2016-001, Regarding Loose Breaker Control Power Fuse Caused the 3B Emergency Containment Cooler to Be Inoperable Longer than Allowed
| ML16109A155 | |
| Person / Time | |
|---|---|
| Site: | Turkey Point  |
| Issue date: | 04/07/2016 |
| From: | Summers T Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-2016-071 LER 16-001-00 | |
| Download: ML16109A155 (4) | |
| 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)(A), Seriously Degraded 10 CFR 50.73(a)(2) 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)(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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) |
| 2502016001R00 - NRC Website | |
text
FPL..
U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555-0001 Re:
Turkey Point Unit 3 Docket No. 50-250 Reportable Event: 2016-001-00 Date of Event: February 8, 2016 L-2016-071 10 CFR § 50.73 APR 0 7 2016 Loose Breaker Control Power Fuse Caused the 3B Emergency Containment Cooler to be Inoperable Longer Than Allowed by Technical Specifications The attached Licensee Event Report 05000250/2016-001-00 is submitted pursuant to 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by the Technical Specifications.
If there are any questions, please call Mr. Mitch Guth at 305-246-6698.
Sincerely,
~
.~ ~--------
/fhomas 1;ummers Vice President Turkey Point Nuclear Plant Attachment cc:
Regional Administrator, USNRC, Region II Senior Resident Inspector, USNRC, Turkey Point Nuclear Plant Florida Power & Light Company 9760 SW 344th St., Homestead, FL 33035
NRC FORM366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2018 (11-2015) l:stimated, the NRG may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Turkey Point Unit 3 05000 250 1 OF 3
- 4. TITLE Loose Breaker Control Power Fuse Caused 3B Emergency Containment Cooler to be Inoperable Longer Than Allowed
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED I
SEQUENTIAL I REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR MONTH DAY YEAR NUMBER NO.
05000 FACILITY NAME DOCKET NUMBER 2
8 2016 2016 -
001 -
00 4
7 2016 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED-PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
D 20.2201(b)
D 20.2203(a)(3)(i)
- D 50.73(a)(2)(ii)(A)
D 50.73(a)(2)(yiii)(A) 1 D
20.2201(d)
D 2*0.2203(a)(3)(ii)
D 50.73(a)(2)(ii)(B)
D 50.73(a)(2)(viii)(B)
D 20.2203(a)(1)
D 20.2203(a)(4)
D so.73(a)(2)(iii)
D 50.73(a)(2)(ix)(A)
D 20.2203(a)(2)(i)
D 50.36(c)(1)(i)(A)
D 50.73(a)(2)(iv)(A)
D 50.73(a)(2)(x)
- 10. POWER LEVEL D
20.2203(a)(2)(ii)
D 50.36(c)(1)(ii)(A)
D 50.73(a)(2)(v)(A)
D 73.71(a)(4)
D 20.2203(a)(2)(iii)
_ D so.36(c)(2)
D 50.73(a)(2)(v)(B)
D 73.71(a)(s>
D 20.2203(a)(2)(iv)
D so.46(a)(3)(ii)
D* 50.73(a)(2)(v)(C)
D 73.77(a)(1) 100 D
20.2203(a)(2)<v>
D 50.73(a)(2)(i)(A)
D 50.73(a)(2)(v)(D)
D 73.77(a)(2)(i)
D 20.2203(a)(2)(vi)
[{] 50.73(a)(2)(i)(B)
D 50.73(a)(2)(vii)
D 73.77(a)(2)(ii)
D 50.73(a)(2)(i)(C)
D OTHER Specify in Abstract below or in DESCRIPTION OF THE EVENT On February 8, 2016 at approximately 0147 hours0.0017 days <br />0.0408 hours <br />2.430556e-4 weeks <br />5.59335e-5 months <br />, during a surveillance test, control room indications identified that 3B Emergency Containment Cooler (ECC) fan [BK, FAN] tripped. Troubleshooting found that the control power fuse [BK, FAN, FU] for the fan's power supply breaker [BK, FAN, BKR] was loose in its fuse holder. The fuse would easily spin inside its fuse holder.
Investigation determined that the fuse holder clips had been widened during work activities associated with the installation of the new breaker for the 3B ECC during the prior Unit 3 refueling and maintenance outage.
The loose control power fuse caused the 3B ECC to be inoperable for approximately 72 days exceeding the Technical Specification (TS) 3.6.2.2, Action 'a' 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 the resultant shutdown requirements for one inoperable ECC. Because the inoperability of the 3B ECC was not recognized at the time, the actions required by TS 3.6.2.2, Action 'a' were not taken, which is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B) as a condition prohibited by the TS.
CAUSE OF THE EVENT
The most probable cause of the loose fuse was improper insertion. In addition, the installation procedure did not validate fuse holder gap, fuse alignment, and fuse tightness after its last removal and insertion prior to placing the new breaker in service.. Inadequate contact during the surveillance test caused the fan trip.
ANALYSIS OF THE EVENT
The ECC System consists of three fan cooling units; each consisting of a motor, fan, bare tube cooling coil, instrumentation and controls. The ECCs, in conjunction with the Containment Spray System (CSS),
prevent containment pressure and temperature from exceeding the values calculated in the containment loss of coolant accident (LOCA) analysis and the main steam line break (MSLB) accident analysis, and maintain containment atmosphere below the structural design pressure and temperature.
Two ECCs (3A and 3C) are automatically initiated via the sequencer on a safety injection (SI) signal. The 3B ECC will start on the failure of either 3A or 3C ECC to start and run. The removal of heat and moisture from the containment is accomplished by recirculating the containment air/vapor mixture to the outside* of the ECC coils by the fan. Heat is then absorbed by the Component Cooling Water (CCW) System which is circulating through the ECC coils. The condensed moisture is drained to the containment sump.
The CCW inlet valves to each ECC unit remain open during both normal operation and after SI signal initiation. The outlet valves are closed during normal operation, but are opened upon start of the associated ECC unit. The outlet valve is controlled by a solenoid valve powered from the same 3B ECC breaker. The (11-2015)
- 1. FACILITY NAME Turkey Point Unit 3 LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 2. DOCKET NUMBER I 05000-1 250 Page 3 of 3 U.S. NUCLEAR REGULAT,ORY COMMISSION
- 3. LER NUMBER r:::-:1 NUMBER NO I
YEAR.
SEQUENTIAL REV LJ*I 001 1-~
control circmt tor the solenoid valve is designed such that a loss ot power will result m the closure of the outlet valve. Therefore, if the control power fuse for the 3B ECC breaker were to blow or come loose, then it would result in the failure of the fan to start or remain running and failure of the outlet valve to open or remain open. As a result, the 3B ECC would not have relia_bly met its safety function mission time.
ANALYSIS OF SAFETY SIGNIFICANCE The safety significance of having the 3B ECC inoperable for approximately 72 days was determined to be low. A risk assessment shows Incremental Conditional Core Damage Probability and Incremental Conditional Large Early Release Proba~ility are bel'ow the NRC acceptance criteria for minimal risk impact.
CORRECTIVE ACTIONS
Corrective actions are in accordance with Condition Report 2108256 and include:
- 1. The fuse holder clips on the 3B ECC breaker were adjusted to provide a tight fit.
- 2. A review of the operating and test history of recently replaced similar breakers on Units 3 and 4 was performed. As a result, certain breakers were identified and scheduled for a contingency inspection of fuse tightness.
- 3. Future installations and preventative maintenance of similar breakers will check fuse tightness and correct if necessary.
ADDITIONAL INFORMATION
Ell~ Codes are shown in the format [IEEE system identifier, component function identifier, second component function identifier (if appropriate)].
FAILED COMPONENTS IDENTIFIED: None
PREVIOUS SIMILAR EVENTS
None