05000341/LER-2005-004, Regarding Both Residual Heat Removal Low Pressure Coolant Injection Divisions Inoperable Due to Valve Failure
| ML052290283 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 08/10/2005 |
| From: | O'Connor W DTE Energy |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NRC-05-0055 LER 05-004-00 | |
| Download: ML052290283 (5) | |
| 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)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2) 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 |
| 3412005004R00 - NRC Website | |
text
WBlliam T. O'Connor, Jr.
Vice President, Nuclear Generation Fermi 2 6400 North Dixie lhwy., Newport, Michigan 48166 Tel: 734-586-5201 Fax: 734-5864172 DTE Energy' 10 CFR 50.73 August 10, 2005 NRC-05-0055 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 No. 2005-004, "Both Residual Heat Removal Low Pressure Coolant Injection Divisions Inoperable Due to Valve Failure" Pursuant to 10 CFR 50.73(a)(2)(v)(D), Detroit Edison is hereby submitting the enclosed Licensee Event Report (LER) No. 2005-004. This LER documents a June 16, 2005 event when both divisions of the Residual Heat Removal (RHR) Low Pressure Coolant Injection (LPCI) system were declared inoperable due to a failure of E I150-FOl7B, the division 2 LPCI outboard injection valve. This normally open valve failed in the closed position, and would not re-open, affecting the LPCI function of RHR.
No commitments are being made in this LER.
Should you have any questions or require additional information, please contact Mr. Nornan K. Peterson of my staff at (734) 586-4258.
Sincerely, cc:
D. P. Beaulieu
\\J E. R. Duncan NRC Resident Office Regional Administrator, Region III Supervisor, Electric Operators, Michigan Public Service Commission
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NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: No. 3150-0104 Expires 6130i2007 (6.2004) timated burden per response to comply with this mandatory collection request 50 hours5.787037e-4 days <br />0.0139 hours <br />8.267196e-5 weeks <br />1.9025e-5 months <br />.
Reported lessons learned are Incorporated Into the licensing process and fed back to Industry. Send comments regarding burden estimate to the Records and FOtAtPrivacy Service Branch (T-5 F52). U.S.
LICENSEE EVENT REPORT (LER)
Nucdear Regulatory Commission. Washington, DC 20555-0001. or by Internet e-mail to infocollects@nrc.gov. and to the Desk Officer, Office of Information and Regulatory Affairs. NEOB-10202 (3150-0104t). Office of Management and no.
.Budget.
Washington. DC 20503. It a means used to impose an information (See reverse for required nurrber of digits/characters for each block)
Information collection.
- 3. PAGE Fermi 2 05000341 j
I OF 4
- 4. nTLE Both Residual Heat Removal Low Pressure Coolant Injection Divisions Inoperable Due to Valve Failure
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE B. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL EV MONTH DAY YEAR FACIUTY NAME DOCKET NUMBER 2
NUMBER NO 05000 06 16 2005 2005 004 00 08 10 2005 FACILITY NAME DOCKETNUMBER 05000
- 9. OPERATING MODE
- 11. THIS REPORT SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Checkall that apply) 0 20.2201(b) 0 20.2203(a)(3)(i) 0 50.73(a)(2)(i)(C) 0 50.73(a)(2)(vii) 0j 20.2201 (d) 0 20.2203(a)(3)(ii) 0 50.73(a)(2)(ii)(A)
] 50.73(a)(2)(viii)(A) a 20.2203(a)(1) 0 20.2203(a)(4) 0 50.73(a)(2)(i)(B)
D 50.73(a)(2)(viii)(B) 20.2203(a)(2)(i) 0 50.36(c)(1)(i)(A) 0 50.73(a)(2)(tii) 0 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL 0 20.2203(a)(2)(ii)
E 50.36(c)(1)(ii)(A) 0 50.73(a)(2)(iv)(A)
U 50.73(a)(2)(x)
D 20.2203(a)(2)Ciii) 0 50.36(c)(2) 0 50.73(a)(2)(v)(A) 0 73.71 (a)(4) 100%
0 20.2203(a)(2)Civ) 0 50.46(a)(3)(ii) 0 50.73(a)(2)(v)(B) 073.71 (a)(5) 0 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A) 0 50.73(a)(2)(v)(C) 0 OTHER 0 20.2203(a)(2Xvi) 0 50.73(a)(2)(i)(B) i 50.73(a)(2)(v)(D)
Spedy In abstract below or In (If more space is required, use additional copies of NRC Form 366A)
Initial Plant Conditions
Mode I
Reactor Power 100 percent Description of the Event On June 16, 2005 at 0923 EDT, with the plant in Mode 1 at 100% reactor power, both divisions of Residual Heat Removal (RHR) [BO] were declared inoperable for the Low Pressure Coolant Injection (LPCI) mode of operation due to a failure of motor operated valve [ISV] El 150-F017B, the division 2 LPCI outboard injection valve.
While performing the division 2 RHR pump and valve operability surveillance test following a planned division 2 RHR system outage, El 150-FO17B closed properly but failed to open during its required stroke time test.
The Fermi 2 accident analysis takes credit for the proper operation of the LPCI loop select logic during a loss of coolant accident (LOCA). The loss of coolant event involves the postulation of a spectrum of piping breaks inside the primary containment varying in size, type and location. The most severe nuclear system effects and the greatest release of material to the primary containment result from a complete circumferential break of one of the two reactor recirculation loop [AD] pipe lines. This is the design basis accident (DBA). Since the LPCI system injects water into the reactor vessel through the discharge piping of one of the recirculation loops, a loop selection logic is provided to ensure that the water is injected into an unbroken loop. The loop selection logic compares pressure on the two recirculation loops. A broken loop will indicate a lower pressure than an unbroken loop.
Where there is no difference in the pressures measured, the default injection is through the B recirculation loop.
Where there is a difference, the loop selection directs the LPCI injection into the high pressure (unbroken) loop.
The loop selection is effected through the operation of the RHR injection valves.
Valve El 150-FO17B is a normally open RHR injection valve in series with the El 150-FO15B valve. These valves control the RHR LPCI flow into reactor recirculation loop B. Had the El 150-FO17B valve failed in the open position, the LPCI function would have been unaffected because the El 150-FO15B valve was available to perform the loop selection task. However, because the valve failed in the closed position, flow would be inhibited into the B recirculation loop for scenarios where a break is detected in loop A or where no recirculation loop break is detected. Therefore, both divisions of RHR were declared inoperable for the LPCI function at 0923 EDT on June 16, 2005. Technical Specification 3.5.1, Action J, was invoked and limiting condition for operation (LCO) 3.0.3 was immediately entered. For scenarios where a break was detected in the B reactor recirculation loop, the LPCI function would be unaffected.
Trouble shooting was performed, and determined that the open contactor auxiliary interlock contact associated with the closing contactor had a high resistance that prevented the proper operation of the open contactor. The closing contactor was manually actuated and the auxiliary contact resistance returned to a normal value. Valve El 150-FO17B was then stroked open electrically which returned it to its normally open position. With the valve in its normally open position, the RHR LPCI function is fully functional. At 1146 EDT, division I RHR was declared operable for the LPCI function, and LCO 3.5.1.J and LCO 3.0.3 were exited.
1U.S. NUCLEAR REGULATORY COMMISSION (1.2001)
LICENSEE EVENT REPORT (LER)
- 1. FACILITY NAME
- 2. DOCKET
- 6. LER NUMBER
- 3. PAGE YEAR SEQUENTIAL REVISION Fermi 2 05000341 NUMBER NUMBER Fri20O31 2005 004 3OF 4 The plant remained at 100% power throughout the event.
Required immediate notifications were made to the NRC in accordance with 10 CFR 50.72 on June 16, 2005 (EN 41780).
This report is being made pursuant to 10 CFR 50.73(a)(2)(v)(D) as a condition that could have prevented the fulfillment of a safety function of a system needed to mitigate the consequences of an accident.
Cause of the Event
The event was caused by a failure of valve El 150-FO17B to re-open during a surveillance test due to a high resistance condition (8.2 Meg-ohm) on the open contactor auxiliary interlock contact associated with the closing contactor. This high resistance condition resulted in the inability of the circuit to energize the contactor open coil.
When the closing contactor was manually actuated, the contact resistance returned to normal, and the valve was able to be opened normally from the main control room. Therefore, the most probable cause of the problem was debris in, or a mechanical binding of, the open contactor auxiliary interlock contact that cleared when the contactor was manually actuated.
The auxiliary contacts were replaced and the original contacts were sent to Detroit Edison's engineering service organization for inspection and evaluation, however, no abnormalities were identified.
Analysis of the Event
The safety function of the LPCI mode of the RHR system is to inject water from the suppression pool into the reactor vessel via injection lines connected to the reactor recirculation piping following a large break LOCA.
Since a large break LOCA could occur in either of the two reactor recirculation loops, the LPCI loop select logic function is designed to select an undamaged reactor recirculation loop for LPCI injection. Reactor recirculation loop B is set up to be the default loop for injection. Therefore, LPCI would always inject via the B loop unless the LPCI loop select logic determines that the break is in recirculation loop B, then recirculation loop A is selected for LPCI injection. Under the conditions of this event, with the Loop B outboard injection valve closed and unable to open, had a LOCA occurred in recirculation loop A or elsewhere in the reactor connected piping systems in containment, the Loop B injection valve would not have opened, thus preventing automatic LPCI injection to the reactor vessel.
Inoperability of the El 150-FO17B valve, for the approximately 2-1/2 hour period on June 16, 2005, rendered both divisions of LPCI inoperable for large break LOCA scenarios except those occurring in recirculation loop B.
However during that period of time the core spray and standby feedwater systems were available to address large break LOCA events. The high pressure coolant injection, reactor core isolation cooling, and standby feedwater systems were also available to address any small break LOCA scenarios that could have occurred at that time. In the probabilistic safety assessment (PSA) analysis, the loss of the LPCI function is of very low safety significance. When coupled with its short duration, this event is considered to be of even lower safety significance. In summary, the effect of this event on plant risk has been evaluated, and it has been determined toU.S. NUCLEAR REGULATORY COMMISSIONI U.S. NUCLEAR REGULATORY COMMISSION (1.2001)
LICENSEE EVENT REPORT (LER)
I
- 1. FACILITY NAME Fermi 2 be of very low safety significance. Therefore, the health and safety of the general public was not adversely affected by this event.
Corrective Actions
Valve El 100-FO17B was returned to its normally open position which restored the full LPCI loop select function.
All of the auxiliary contacts associated with the close contactor were replaced on June 17, 2005.
The original auxiliary contacts were sent to Detroit Edison's engineering service organization for inspection and evaluation, however, no abnormalities were identified.
This event has been documented in the Fermi 2 corrective action program, CARD 05-23618. Additional evaluations are being performed that may result in additional corrective actions. Any further corrective actions identified as a result of these evaluations will be tracked and implemented commensurate with the established processes and priorities of the corrective action program.
Additional Information
A. Failed Components:
Component: Contactor / auxiliary contact block Function: Valve motor control Manufacturer: General Electric Model Number: CR305 Failure Cause: high contact resistance B. Previous LERs on Similar Problems:
There have been no LERs for similar events in the last three years.