05000341/LER-2011-001, Regarding High Pressure Coolant Injection System Inoperable Due to Inoperable Minimum Flow Valve
| ML113060566 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 11/01/2011 |
| From: | Plona J DTE Energy |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| NRC-11-0050 LER 11-001-00 | |
| Download: ML113060566 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v), Loss of Safety Function 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)(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)(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)(i)(B), Prohibited by Technical Specifications |
| 3412011001R00 - NRC Website | |
text
Joseph II. Plona Site Vice President 6400 N. Dixie Highway, Newport, MI 48166 Tel: 734.586.5910 Fax: 734.586.4172 10 CFR 50.73 November 1, 2011 NRC-11-0050 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington D C 20555-0001
Reference:
Fermi 2 NRC Docket No. 50-341 NRC License No. NPF-43
Subject:
Licensee Event Report (LER) No. 2011-001 Pursuant to 10 CFR 50.73(a)(2)(v)(D), Detroit Edison is submitting the enclosed LERNo. 2011-001. This LER documents the September 6, 2011 loss of the High Pressure Coolant Injection System due to an inoperable minimum flow valve.
No commitments are being made in this LER.
Should you have any questions or require additional information, please contact Mr. Rodney W. Johnson of my staff at (734) 586-5076.
Sincerely, Enclosure cc: NRC Project Manager NRC Resident Office Reactor Projects Chief, Branch 4, Region III Regional Administrator, Region III Supervisor, Electric Operators, Michigan Public Service Commission
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: No. 3150-0104 Expires 10/31/2013 (10-2010)
, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Fermi2 05000341 1 OF 3
- 4. TITLE High Pressure Coolant Injection System Inoperable Due To Inoperable Minimum Flow Valve
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED SEQUENTIAL REV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR NUMBER NO.
MONTH DAY YEAR 05000 09 06 2011 2011 001 00 11 01 2011 FACILITYNAME DOCKETNUMBER 05000
- 9. OPERATING MODE
- 11. THIS REPORT SUBMITTED PURSU ANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)
] 20.2201(b) 0 20.2203(a)(3)(i) 0 50.73(a)(2)(i)(C) 0 50.73(a)(2)(vii)
O 20.2201 (d) 20.2203(a)(3)(ii) 50.73(a)(2)(ii)(A) 50.73(a)(2)(viii)(A) 1
[] 20.2203(a)(1) j 20.2203(a)(4) 50.73(a)(2)(ii)(B) 50.73(a)(2)(viii)(B) 20.2203(a)(2)(i) 50.36(c)(1)(i)(A)
]
50.73(a)(2)(iii) 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL O 20.2203(a)(2)(ii)
O 50.36(c)(1)(ii)(A)
]
50.73(a)(2)(iv)(A)
O 50.73(a)(2)(x)
]20.2203(a)(2)(iii) 0 50.36(c)(2)
O 50.73(a)(2)(v)(A) 73.71 (a)(4) 100 0
20.2203(a)(2)(iv) 50.46(a)(3)(ii)
[
50.73(a)(2)(v)(B) 73.71(a)(5)
S20.2203(a)(2)(v) 50.73(a)(2)(i)(A)
]
50.73(a)(2)(v)(C)
O OTHER 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B)
. [
50.73(a)(2)(v)(D)
Specify in abstract below or in NRC Form 366A
- 12. LICENSEE CONTACT FOR THS LER FACILITY NAME TELEPHONE NUMBER (Include Area Code)
Fermi 2 / Rodney W. Johnson - Manager, Nuclear Licensing (734) 586 - 5076CAUSE SYSTEM COMPONENT MANU-REPORTABLE
CAUSE
SYSTEM COMPONENT MANU-REPORTABLE FACTURER TO EPIX FACTURER TO EPIX B
BJ MO P296 Yes
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTH DAY YAR SUBMISSION MONTH DAY YEAR SUBMISSION O
YES (If yes, complete 15. EXPECTED SUBMISSION DATE)
F NO DATE ABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On September 6, 2011, at approximately 0104 EST during surveillance testing of the High Pressure Coolant Injection (HPCI) system, control room position indication was lost on the HPCI minimum flow valve as the valve was stroking closed following shutdown of HPCI. The minimum flow valve main power fuses were checked, found blown, and replaced. During a subsequent stroking of the valve, control room position indication was lost and main power fuses found blown when the open pushbutton was depressed.
The valve was locally verified closed to comply with the Technical Specification Action of Limiting Condition for Operation (LCO) 3.6.1.3 to isolate the penetration. A 14-day LCO was entered per Technical Specification Action 3.5.1.
System troubleshooting, diagnostic testing, and analysis were performed. The minimum flow valve motor series winding was determined to have developed turn-to-turn shorts causing the fuses to blow. The HPCI minimum flow valve motor, valve torque switch, thermal overloads, and Motor Control Center (MCC) main and auxiliary contactors were replaced. Circuit leads were inspected and tightened, and power fuse tightness was verified during fuse replacement. Post maintenance testing was successfully completed and, the HPCI system was returned to service on September 10, 2011 at 2300 EST. The safety consequences of this event were determined to be low.
NRC FORM 366 (10-2010)
Initial Plant Conditions
Mode 1
Reactor Power 100 percent Description of the Event On September 6, 2011, at approximately 0104 EST surveillance testing of the High Pressure Coolant Injection (HPCI) [BJ] system per procedure 24.202.01 "HPCI Pump Time Response and Operability Test at 1025 PSI,"
was in progress. The HPCI turbine was in the process of coasting down at the end of the surveillance test, and at the point where the minimim flow valve should have closed, indication was lost on the open and closed pushbuttons. Alarm 2D73 (HPCI MOVS MTR OVERLOAD / LOSS OF POWER SUPPLY) was received.
Initial troubleshooting determined the minimum flow valve main power fuses [FU] were blown. The fuses were replaced, and during a subsequent stroking of the valve, control room position indication was immediately lost when the open pushbutton was depressed. Both primary power fuses were again found blown which were subsequently replaced and the breaker re-energized. Once the breaker was re-energized the closed indication was restored in the control room.
The valve was locally verified closed to comply with the Technical Specification Limiting Condition for Operation (LCO) 3.6.1.3 to isolate the containment penetration. A 14 day LCO was entered for HPCI system inoperable per Technical Specification Limiting Condition for Operation (LCO) 3.5.1. The Reactor Core Isolation Cooling (RCIC) system remained operable during this time.
Troubleshooting activities were expanded into the valve and control circuits. The HPCI minimum flow valve motor, valve torque switch, and Motor Control Center (MCC) main and auxiliary contactors were replaced.
Circuit leads were inspected and tightened, and power fuse tightness was verified during fuse replacement.
Thermal overloads were also replaced. Post maintenance testing was successfully completed and the HPCI system was returned to service on September 10, 2011 at 2300 EST.
Significant Safety Consequences and Implications
The HPCI system, a single train safety system, was rendered inoperable when the operation of the HPCI minimum flow valve was determined to be unreliable and the valve was declared inoperable. The purpose of the HPCI system is to provide emergency core cooling in the event of an accident involving loss of coolant from a small break. Reactor steam is used to drive the HPCI turbine, which in turn drives the main and booster pumps to provide a source of high pressure water to the reactor. The Reactor Core Isolation Cooling [BN] and Standby Feedwater [SJ] systems remained available for high pressure injection in the event of an emergency.
Additionally, the Automatic Depressurization System [JE] was available to reduce reactor pressure to within the capabilities of the low pressure Emergency Core Cooling Systems.U.S. NUCLEAR REGULATORY COMMISSION (10-2010)
LICENSEE EVENT REPORT (LER)
CONTINUATION SHEET
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE YEAR SEQUENTIAL REVISION Fermi 2 05000341 NUMBER NUMBER 3 OF 3 2011 001 00 This event resulted in approximately 5 days where HPCI was inoperable. Technical Specification 3.5.1 allows HPCI to be taken out of service for planned outages for up to 14 days. This risk increase associated with HPCI being out of service for approximately 5 days has been evaluated by the Probabilistic Safety Analysis (PSA) group and determined to be low.
This report is made in accordance with 10 CFR 50.73(a)(2)(v)(D), for any event or condition that could have prevented the fulfillment of a safety function of a system needed to mitigate the consequences of an accident. An eight-hour non-emergency notification was also made pursuant to 10 CFR 50.72(b)(3)(v)(D) as a condition that at the time of discovery could have prevented the fulfillment of a safety function (EN 47242).
Cause of the Event
The HPCI minimum flow valve motor (MO) was sent for failure analysis which determined the valve motor series winding had developed turn-to-turn shorts. The shorted winding caused the main power fuses to blow. A root cause evaluation team continues to investigate the problem.
Corrective Actions
The HPCI minimum flow valve motor and main power fuses were replaced. Additionally, the HPCI minimum flow valve motor operated valve torque switch, thermal overloads and MCC main and auxiliary contactors were replaced. Circuit leads were inspected and tightened, and power fuse tightness verified during fuse replacement.
Thermal overloads were also replaced. This event has been documented in the Fermi 2 Corrective Action Program and additional actions may be taken as determined by the program.
Additional Information
A.
Failed Component:
Component: Motor Function: Valve Actuator Manufacturer: Peerless Electric Model Number: Frame DK56H Failure Cause: Shorted Winding B.
Previous LERs on Similar Problems:
A similar problem was identified in Licensee Event Report 2010-04, "High Pressure Coolant Injection System Inoperable Due To Inoperable Minimum Flow Valve." However, that failure was determined to be caused by a failed contactor. The HPCI minimum flow valve motor was also replaced as a precaution in December, 2010, when the contactor failed.
Since the cause of the current failure (a failed valve actuator motor) is different from the LER 2010-04 failure (failed contactor), the corrective actions for the previous LER would not be expected to be effective in addressing the problem identified in this LER.