05000389/LER-2002-002, Regarding Found Cycle 12 Pressurizer Safety Valve Setpoints Outside TS Limits
| ML022890099 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 10/14/2002 |
| From: | Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-2002-195 LER 02-002-00 | |
| Download: ML022890099 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 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) 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3892002002R00 - NRC Website | |
text
FPL Florida Power & Light Company, 6501 South Ocean Drive, Jensen Beach, FL 34957 October 14, 2002 L-2002-195 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: 2002-002-00 Date of Event: August 19, 2002 As-Found Cycle 12 Pressurizer Safety Valve Setpoints Outside Technical Specification Limits The attached Licensee Event Report 2002-002 is being submitted pursuant to the requirements of 10 CFR § 50.73 to provide notification of the subject event.
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- yours, Donald E.
Vice President St. Lucie Nuclear Plant DEJ/KWF Attachment I ".- ;)
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an FPL Group company
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB NO. 3150-0104 EXPIRES 6-30-2001 (1-2001)
, the NRC may not conduct or sponsor, and a person Is not required to respond to, the Information collection lFAUILI I Y NAMt (1)
[IOCKt NUMBER (2) 1'FAGh t4)
St. Lucie Unit 2 05000389 Page 1 of 5 IllLt (4)
As-Found Cycle 12 Pressurizer Safety Valve Setpoints Outside Technical Specification Limits EVtNI UA If=)
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MONTH DAY l YEAR SEQUENTIAL REVISION l MONTH DAY YEAR lACILITY NAMt DOCKET NUMbER NU M BER N
iM BE R 1l ACiLITY NAM E DOCKET NUM BER 08 1 9 2002 2002 002 00 10 14 2002 FL D
OPERATING i i
THIS REPORT IS SUBMIETD PURSUANTTO t E Rt QUIREMNT OF 10 CFR §. (Check one or more) (11)
MODE (9) j 1_
ll___ 20.2201(b) 20 2203(a)(3)(a) 50 73(a)(2)(X)(B) 50 73(a)(2)(ix)(A)
POWER I
20 2201(d) 20.2203(a)(4) 50 73(a)(2)(111) 50 73(a)(2)(x)
LEVEL (10) 100 l -20.2203(a)(1) 50 36(c)(1)(1)(A) 50 73(a)(2)(tv)(A) 73 71(a)(4) 20.2203(a)(2)(i) l 50.36(c)(1)(ll)(A) 50 73(a)(2)(v)(A) 7371 (a)(5) 20.2203(a)(2)(ll) 50 36(c)(2) 50.73(a)(2)(v)(B)
OTHER l l20.2203(a)(2)()
l 50 46(a)(3)(ii) 50 73(a)(2)(v)(C)
Specif in Abstract below 20 2203(a)(2)(mv) 50 73(a)(2)(l)(A) 50.73(a)(2)(v)(D) 20 2203(a)(2)(v)
X 50 73(a)(2)(i)(B) 50.73(a)_2)(vil) 20 2203(a)(2)(vi) 50.73(a)(2)(i)(C) 150 73(a)(2)(vll)(A) 20 2203(a)(3)(i) 50 73(a)(2)(n)(A) 150 73(a)(2)(viii)(B)
LICENSEE CONTACT FOR THIS LER (12)
NAME 1 icLLFrINUMECE tinouCe Area Loca)
Kenneth W. Frehafer, Licensing Engineer I
(772) 467 7748 CUMlI'LtEl UNt LINt FUK tA(.H1 CUMFUNtN I FAILURt UtCiU SU IN I Hlb REI'ORI (1J)
CAUSE
SYSTEM COMPONENT MANUFACTURER REPORTABLE l
CAUSE
SYSTEM COMPONENT MANUFACTURER REPORTABLE CUE SSE COPNN MAUATRR TO EPIX N
T1 TO EPIX X
l AB RV C170 NO l
,bUPI`rLtEMhNIAL KtR'UKI EXPUEC I U (14)
EXE____A EXPECTED I
YEAR YES I
SUBMISSION 1
(If yes, complete EXPECTED SUBMISSION DATE)
Xj NO DATE (15)
ABSTRACT (LIM~ttO 74UU spacesie, approximareiyio singie-spacuu yptWIIwiU[nIlillWj k10j On August 19, 2002, St. Lucie Unit 2 was in Mode 1 at approximately 100 percent reactor power. Wyle Labs informed FPL of unsatisfactory test results for two of the three code pressurizer safety valves removed during the Cycle 13 refueling outage.
Wyle Labs was contracted to perform the offsite pressurizer safety valve testing and the testing was conducted within the required time restraints.
Technical Specification 3.4.2.2 requires the as-found setpoints of the pressurizer safety valves to be 2 2435.3 psig and
- 2535.3 psig.
The as-found settings of two St.
Lucie Unit 2 pressurizer safety valves were 2.37 and 3.66 percent high, outside the Technical Specification tolerance limit of +/- 2 percent.
The cause of the failed pressurizer safety valve tests was due to valve spring performance issues and mechanical setpoint drift over the operating cycle.
There is no past or present operability concern as the subject pressurizer safety valves were removed and replaced with pre-tested valves during the St. Lucie Unit 2 Cycle 13 refueling outage.
There was no affect on the health and safety of the public during past St. Lucie Unit 2 Cycle 12 power operations because the limiting overpressure analyses remain bounding for the as-found condition.
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LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1) l[ N LER NUMBER (6)
PAGE (3) l YEAR SEQUENTIAL REVISION YEAR NUMBER NUMBER St. Lucie Unit 2 05000389 N
Page 2 of 2002 002 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)
Description of the Event On August 19, 2002, St. Lucie Unit 2 was in Mode 1 at approximately 100 percent reactor power.
Wyle Labs informed FPL of unsatisfactory test results for two of the code pressurizer safety valves (PSVs) [EIIS:AB:RV] removed during the Cycle 13 refueling outage.
In accordance with the inservice testing (IST) program, pressure relief devices are tested per ANSI/ASME OM-1987, Part 1, "Requirements for Inservice Performance Testing of Nuclear Power Plant Pressure Relief Devices." Section 1.3.3, 'Test Frequency, Class 1 Pressure Relief Devices," of the code requires testing within 12 months of removal from service when the surveillance requirements are satisfied by installing a full complement of pre-tested valves.
Wyle Labs was contracted to perform the testing and the testing was conducted within the required time restraints.
Technical Specification 3.4.2.2 requires the PSVs to lift at 2500 psia (+/- 2 percent).
The as-found settings of two of the Unit 2 PSVs were outside the Technical Specification tolerance limit of +/- 2 percent.
As shown below, the deviation was 2.37 and 3.66 percent high for the two failed valves.
Jo,-I lSerial Number l ee l Acceptable Range As-fsound Set Reul I
Pr I Pressure V1202 N84217-00-0002 l 2500 psia 2435.3-2535.3 psig l 2544 psig
+2.37%
l V1200 N84217-00-0006 2500 sia 2435.3-2535.3 si 2576 si
+3.66%
No present operability concern exists, as the PSVs were all removed and replaced with pre-tested valves during the St. Lucie Unit 2 Cycle 13 (SL2-13) refueling outage under work orders (WO) 30023161, 30023162, and 30023163.
Cause of the Event
ANSI/ASME OM-1987, Part 1, code requires a cause determination and corrective actions for any safety or relief valve that exceeds its nameplate setpressure by 3 percent or greater. The As Found setpressure of Unit 2 PSV V1200, S/N N84217-00-0006, was 2576 psig.
This is 3.66 percent above the nameplate 2485 psig setting.
Following the as-found (first test) failure and prior to disassembly, additional tests were conducted to evaluate the valve's health and actual setting.
The second and third test results were 2522 and 2548 psig respectively.
These tests were performed immediately following the as-found test with no adjustments to the valve.
Historically, after exercising the valve, setpoint drift is no longer present and the setting is at or near the expected value.
This did not occur as shown by the second and third data points and implies that a hardware problem existed.
The valve was then disassembled and inspected by Crosby, the OEM vendor.
The visual inspection did not identify any wear or other hardware concerns.
All of the load bearing surfaces, contact points, and internal guides were satisfactory.
The valve was dimensionally verified against Crosby design drawings and found to be acceptable.
No hardware problems were found that would cause the high setting.
Based on the results of the valve inspection, the most likely cause for the surveillance failure was performance problems with the valve spring.
A review of past surveillance data revealed that this valve failed high in 1999.
Crosby, the OEM vendor, concluded that the spring assembly needed to be replaced.
This work was I
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(1-2001)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
NUMBER 2)
LER NUMBER (6)
PAGE (3)
' YEAR SEQUENTIAL REVISION
~7NUMBER NUMBER e3o5 St. Lucie Unit 2 05000389 Page 3 of 5 l
l 2002 002 00 l
TEXT (Ifmorespaceisrequired, useaddtionalcopiesofNRCForm366A) (17) performed and the valve was re-certified on August 1, 2002.
No abnormalities were identified during the As-left testing.
The as-found setpressure for V1202, S/N N84217-00-0002, was 2544 psig, or 2.37 percent above the nameplate 2485 psig setting. The valve had not failed high in previous tests.
The apparent cause for the failure to meet the Technical Specification surveillance requirements is setpoint drift.
The spring was replaced as a prudent measure and the valve was successfully re-certified.
Analysis of the Event
FPL reviewed NUREG-1022, Revision 1, "Event Reporting Guidelines 10 CFR 50.72 and 50.73," and determined that this event is reportable under 10 CFR 50.73(a)(2)(i)(B) as "any operation or condition prohibited by the plant's Technical Specifications."
Although discrepancies found in Technical Specification surveillance tests should be assumed to occur at the time of the test, the existence of multiple sequential test failures involving safety valves may be an indication that the discrepancies arose over a period of time.
Therefore, the condition may have existed during plant operation.
Analysis of Safety Significance An engineering assessment of the accident analysis was performed to determine if the setpoint deviations could have led to the violation of overpressurization limits during the operation of Cycle 12.
The assessment performed here accounts for the effects of main steam safety valves (MSSVs) setpoint deviations found at the end of Cycle 12 and reported by LER 50-389/2001-002-00.
The function of PSVs in the safety analysis is to mitigate the consequences of overpressurization events to limit the peak pressure below the acceptance limits.
The limiting overpressurization events are in the category of "Decrease in Heat Removal by the Secondary System.'
The limiting events in this category, pertaining to deviations in PSV setpoints, are the Feedline Break and the Loss of Condenser Vacuum. In addition to these "Decrease in Heat Removal" events, PSV setpoints are used as input in the analysis of the CEA Withdrawal (CEAW) event.
The key parameter inputs (other than PSV and MSSV setpoints that are discussed below) used in the analyses of these events bound the values for Cycle 12.
LER 50-389/2001-002-00 concluded that the deviations in the as-found MSSV setpoints had no adverse impact on the safety analysis results.
CEAW The current analysis of the CEAW event assumes the opening of the PSVs at 2500 psia +
3 percent tolerance.
CEAW event is not limiting with respect to the RCS pressure and the fact that the RCS pressure in the analysis does not reach this analysis value for valve opening pressure of 2575 psia concludes that this event analysis remains bounding for the as-found PSV conditions.
This conclusion is valid even after taking into account the MSSV set pressure deviations as reported by LER 50-389/2001-002-00.
Feedline Break The Feedline Break analysis of record used a conservative PSV setpoint of 2575 psia and showed acceptable results with respect to the overpressurization criteria for primary and secondary systems.
Since the average as-found setpressure of the PSVs was 2544 psia (<2575 psia), the results of the current analysis bound the Cycle 12
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- - U.S. NUCLEAR REGULATORY COMMISSION (1-2001)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1) 1NB()
LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL REVISION YER NUMBER NUMBER St. Lucie Unit 2 05000389 l N
Page 4 of 5 2002 002 00 TEXT (Ifmore space is required, use addtional copies of NRC Fornm 366A) (17) operation with these as-found setpoints.
(A lower PSV setpoint would open the valves earlier helping in the mitigation of the overpressurization event.)
Loss of Condenser Vacuum This is the limiting pressurization event for St. Lucie Unit 2. The loss of condenser vacuum analysis of record used a PSV setpoint of 2550 psia (a 2 percent tolerance) and showed acceptable results with respect to the overpressurization criteria for primary and secondary systems.
Since the average as-found setpressure of the PSVs was 2544 psia (<2550 psia), the current analysis remains bounding for the as-found setpressure condition of the PSVs. This conclusion is valid even after taking into account the MSSV set pressure deviations reported by LER 50-389/2001-002-00.
Conclusion Based on the evaluation performed, it is concluded that no safety analysis limits would have been violated for any of the FSAR analyzed events during the operation of Cycle 12.
The operation of Cycle 12 would have remained within the design basis of the plant.
Generic Implications The spring concern is only applicable to both units PSV and the spare valves because no other valves use this same spring.
The IST and relief valve planned maintenance programs monitor the health of other safety and relief valves.
All three PSVs are replaced each outage in accordance with the PM program to minimize aging and setpoint drift concerns.
All nine valves (three per unit and three spares) are closely monitored and the setpoints trended due to their importance.
FPL determined that the installed PSVs on both units could reasonably accommodate the historical setpoint drift data reviewed.
Corrective Actions
- 1. The refurbishment and re-testing of the valves removed from Unit 2 during SL2-13 were completed.
- 2. The spring assemblies for valve SINs N84217-00-0002 and N84217-00-0006 were replaced.
Additional Information
Failed Components Identified Component:
pressurizer safety valve Manufacturer: Crosby Model:
HB-86-BP, forged block body design, size 3K6, assembly N84217 t 4 :U.S. NUCLEAR REGULATORY COMMISSION l1-2001)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
NUMBER LER NUMBER (6)
F PAGE (3)
YEAR EQUENTIAL REVISION E NUMBER NUMBER St. Lucie Unit 2 05000389 Page 5 of 5 2002 002 00 TEXT (If more space is required, use addibonal copies of NRC Fonm 366A) (17)
Similar Events
LER 50-389/2000-004-00, "As-Found Cycle 11 Pressurizer Safety Valve Setpoints Outside Technical Specification Limits."
LER 50-389/2001-002-00, "As-Found Cycle 12 Main Steam Safety Valve Setpoints Outside Technical Specification Limits."