05000389/LER-2006-002, Re Containment Purge Supply Isolation Valve Failure
| ML061150370 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 04/17/2006 |
| From: | Johnston G Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-2006-105 LER 06-002-00 | |
| Download: ML061150370 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 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)(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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3892006002R00 - NRC Website | |
text
FPL.
Florida Power & Light Company, 6501 S. Ocean Drive, Jensen Beach, FL '14957 April 17, 2006 L-2006-10C5 10 CFR § 50.73 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D. C. 20555 Re:
St. Lucie Unit 2 Docket No. 50-389 Reportable Event: 2006-002-00 Date of Event: February 15, 2006 Containment Purge Supply Isolation Valve Failure The attached Licensee Event Report 2006-002-00 is being submitted pursuant to the requirements of 10 CFR § 50.73 to provide notification of the subject event.
Very truly yours, Gordon L. Johnston Acting Vice President St. Lucie Nuclear Plant to7 SVP GLJ/dlc Attachment CD, -e (;) D an FPL Group company
- - Iv I---
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRE-S: 06130/2007 (6-2004)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 11. FACILITY NAMIE 2.DOCKET NUMBER 3AGI St. Lucie Unit 2 05000389 Page 1 of 3
- 4. TITLE Containment Purge Supply Isolation Valve Failure
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVEDI MONTH DAY YEAR YEAR NUMBER NUMBER MONTH DAY YEAR NAME 02 15 2006 2006 002 00 04 17 2006 TXMTYNAME DOCETNUMB l
- 19. OPERATING MDEid.THIS REPORTISSUBMITTED PURSUANTTOTHE REQUIREMENTS OF 10 CFR§: (Checkalltha:apply) l1 l
20.2201(b) a3 20.2203(a)(3)(i)
Dl 50.73(a)(2)(i)(C)
D 50.73(al(2)(vii) ol 20.2201(d)
El 20.2203(a)(3)(ii)
El 50.73(a)(2)(ii)(A) a 50.73(at(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4) al 50.73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
El 20.2203(a)(2)(i)
[I 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii)
El 50.73(aI(2)(ix)(A)
- 10. POWER LEVEL 0
20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A)
El 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x) 1 00 El 20.2203(a)(2)(iii)
El 50.36(c)(2)
El 50.73(a)(2)(v)(A)
[I 73.71 (a)(4)
El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii) 0 50.73(a)(2)(v)(B)
El 73.71 (a)(5) ll 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
[I OTHER SMeM irn Ab~s~ract below or in ll 20.2203(a)(2)(vi) 3 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
NSCpeci i3 A
- 12. LICENSEE CONTACT FOR THIS LER NAME TELEPHONE NUMBER (Include Area Code)
Donald L. Cecchett -
Licensing Engineer (772) 467 -
7155
_13.CMPLE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT
CAUSE
SYSTEM COMPONENT MANUFACTURER REPORTABLE
CAUSE
SYSTEM COMPONENT MANUFACTURER REPORTABLE BF FCV C630 YES
-=
OMPONNTlMA CASE SSTM OPOEN ANFATRE T
PI SSEMPEE T
U DACTRR TOEY T4UPPLEMENTAL REPORT EXPECTED 15 EXPECTED MO YEAR
__YES SUBMISSION I
IA Il (If yes, complete EXPECTED SUBMISSION DATE).
X NO
[
DATE ABSTRACT (Limil to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)
On February 15, 2006, with St. Lucie Unit 1 and Unit 2 in Mode 1 at 100 percent power, the St. Lucie Unit 2 inboard 8-inch containment purge supply isolation valve FCV-25-2-6 failed its local leak rate test (LLRT).
The LLRT was being performed as required by Technical Specification (TS) surveillance requirement 4.6.1.7.4.
Valve FCV-25-36 is the Containment side isolation valve for penetration P-56.
Failure of the leak test caused entry in TS Action 3.6.1, requiring the penetration to be restored. to operable status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, or be in hot shutdown within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
As a result of the suspected failure mode of the isolation valve, and obstacles involved in repairing the valve within the TS required 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, St. Lucie requested and received. a Notice of Enforcement Discretion (NOED) from the NRC.
As support for NOED-06-2-01, the valve was removed, a blank flange installed, and the LLRT successfully performed.
The valve has since been repaired and returned to service.
Additionally, an exigent TS chance has been approved to adopt the Improved Standard Technical Specification which allows operation to continue with a blank flange installed or the upstream valve closed and de-energized.
NRC FORM 366 (6-2004)U.S. NUCLEAR REGULATORY COMMISSION (6-2004)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION
- 1. FACILITY NAME
- 2. DOCKET LER NUMBER
- 3. PAGE YEAR SEQUENTIAL REVISION I
NUMBER NUMBER St. Lucie Unit 2 05000389 Page 2 of 3 2006 002 00 TEXT (If more spice is required, use additional copies of NRC Form 366A) (17)
Description of the Event While performing a Local Leak Rate Test (LLRT) on Unit 2's penetration P-56 (Mini Purge), using Operation procedure "Purge Valve Leak Rate Test," leakage exceeded the TS defined limits.
Initial troubleshooting determined that FCV-25-36 [EIIS:BF:J14],
the inside 8-inch containment isolation valve, was not fully closed.
Given the suspected failure mode of the isolation valve, and the obstacles to repair the valve within rS limits, a NOED (NOED-06-2-01) was pursued and granted.
The valve was removed from the system, a blind flange installed, and the LLRT successfully performed.
Cause of the Event
Following removal of the valve, an Apparent Cause Evaluation (ACE) was conducted.
The apparent cause of the failure was attributed to inadequate corrective maintenance.
Investigation of the valve indicated FCV-25-36 failed to close as a result Df binding between the valve stem and body bushings caused by galling and "balling" of material.
This restriction lead to an increase in friction that could not be overcome by the actuator spring to provide a leak-tight seal for the LLRT, but closed enough to indicate closure to the Operators.
Analysis of the Event
A review of the valve's history showed the valve had been inspected and overhauled during the previous outage (SL2-15).
At that time, a new disk and stem were scheduled to be installed, however, like-for-like replacements were not available.
Although the stem had signs of wear damage, the decision was made to the repair and reuse the existing stem.
Further investigation indicates the galling between the valve stem and body bushings was mos: likely initiated by damage that occurred during the SL2-15 overhaul of the valve or ineffective repair of the valve during the overhaul.
Reuse of the refurbished stem and/or damaged body bushings may have contributed to the failure.
This event is reportable under 10 CFR 50.73 (a) (2) (i) (B) as "any operation or condition which was prohibited by the plant's Technical Specifications_."
because the valve could not be returned to service within TS allowable limits.
Analysis of Safety Significance The containment purge valves are part of the containment purge and the continuous purge/hrydrogen purge systems.
The 8-inch purge (or mini-purge) system is not required for safe shutdown of the reactor or to mitigate the consequences of a design basis accident.
The containment purge system is designed to reduce the level of radioactive contamination in the containment atmosphere below the limits of 10 CFR 20 so as to permit personnel access to the containment during shutdown and refueling.
It is also used to relieve the building of pressure in the containment caused by leak-by of instrument air-operated components.
The continuous purge/hydrogen purge system can be used as a not-nuclear-safety backup to the redundant safety-related hydroge:n recombiners, which maintain containment hydrogen concentration below 4 percent after a postulated accident.
The only portions of the mini-purge system that arei safety-related are the containment penetrations and the isolation valves.
NKR 1-UFM 366A (6 Z004)
--IU.S. NUCLEAR REGULATORY COMMISSION (6-2004)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION
- 1. FACILITY NAME
- 6. LER NUMBER NUMBER NUMBER 2006 002 00 St. Lucie Unit 2 TEXT (if more spa ce is required, use additional copies of NRC Form 366A) (17)
Corrective Actions
The pro-osed corrective actions and supporting actions listed below are entered into the site corrective action program.
Any changes to the proposed actions will be managed under the commitment management change program.
Replace the valve stem and body bushings and reinstall the valve (Complete)
Exigent Technical Specification Change Amendment Number 142 for Unit 2, a:proved March 17, 2006.
(Implemented)
Will develop a repair procedure for the FCV-25-36 valve prior to the next scheduled valve overhaul.
Similar Events
A review of industry Operating Experience (OE) identified no common failure issues.
The review identified only one similar OE, regarding a Contromatics Motor Operated Valve (0,0V) that failed to fully close as a result of seat degradation and wear of bronze bearings.
However, because of differences in materials and failure mode (seat vs. stem galling), this OE is not considered relevant to this event.
Failed Components Contromatics Valve, Tag Number, FCV-25-36, Model, Control-Seal Type II valve with SRMSV Actuator and Mastergear MCF-60 manual operator.