05000389/LER-2006-003, Re Missed Eddy Current Indication from SL2-15 Inspection
| ML061870466 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 06/28/2006 |
| From: | Johnston G Florida Power & Light Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| L-2006-153 LER 06-003-00 | |
| Download: ML061870466 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3892006003R00 - NRC Website | |
text
FPL Florida Power & Light Company, 6501 S. Ocean Drive, Jensen Beach, FL 34957 June 28, 2006 L-2006-153 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: 2006-003-00 Date of Event: May 6, 2006 Missed Eddy Current Indication from SL2-15 Inspection The attached Licensee Event Report 2006-003-00 is being submitted pursuant to the requirements of 10 CFR 50.73 to provide notification of the subject event.
Very
- yours, Site Vice President St. Lucie Plant GLJ/dlc Attachment 922-an FPL Group company
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 06/30/2007 (6-2004)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
I. FACILITY NAME
- 2. DOCKET NUMBER
- 3. PAGE St. Lucie Unit 2 05000389 1
OF 4
- 4. TITLE Missed Eddy Current Indication from SL2-15 Inspection
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED MONTH DAY YEAR YEAR SEQUENTIAL REV MONTII DAY YEAR UFACMLTY NAME DOCKET NUMNER 05 06 2006 2006 -
003 -
00j 6
28 2006
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO TIlE REQUIREMENTS OF 10 CFR§: (Check all that apply)
[1 20.2201(b)
[I 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C)
[: 50.73(a)(2)(vii) 6 0 20.2201(d) 0 20.2203(a)(3)(ii)
EC 50.73(a)(2)(ii)(A)
El 50.73(a)(2)(viii)(A)
C 20.2203(a)(I)
El 20.2203(a)(4)
EC 50.73(a)(2)(ii)(B)
EC 50.73(a)(2)(viii)(B)
C 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
C 50.73(a)(2)(iii)
C 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL C 20.2203(a)(2)(ii)
El 50.36(c)(I)(ii)(A)
C 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
C 20.2203(a)(2)(iii) 0 50.36(c)(2)
C 50.73(a)(2)(v)(A)
El 73.71(a)(4)
CJ 20.2203(a)(2)(iv)
[I 50.46(a)(3)(ii)
EC 50.73(a)(2)(v)(B)
El 73.71(a)(5) 0 EC 20.2203(a)(2)(v)
[I 50.73(a)(2)(i)(A)
EC 50.73(a)(2)(v)(C)
El OTHER E] 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
Specify in Abstract below or in NRC Form 366A
- 12. LICENSEE CONTACT FOR THIS LER NAME TELEPHONE NUMBER (include Area Code)
Donald L. Cecchett - Licensing Engineer 1
772-467-7155CAUSE SYSTEM COMPONENT FACTURERMTO EPORTABEIX
CAUSE
SYSTEM COMPONENT FACUR REPIA FATRE O PXFAtZTURER TO EPIX
- 14. SUPPLEMENTAL REPORT EXPECTED
- 15. EXPECTED MONTHt DAY YEAR SUBMISSION
[: YES (Ifyes, complete 15. EXPECTED SUBMISSIONDATE) 0 NO DATE
- - S S
ABSTRACT (Limit to 1400 spaces, i.e.* approximately 15 single-spaced tpewritten lines)
On May 6, 2006, St. Lucie Unit 2 was in Mode 6, shutdown for the SL2-16 refueling outage. During steam generator eddy current testing (ECT),
FPL determined that an error I
was made during the previous refueling SG ECT that allowed a defect in a steam generator tube (R100 L96 in SG 2B) to! remain in service during Cycle 15 operation.
This event was caused by an incomplete rotating probe inspection of bobbin probe identified indications during SL2-15.
Corrective actions included plugging of the subject tube, and review of rotating probe data to ensure the entire target location was tested where the data was used to disposition a bobbin indication as "no degradation found" (NDF) during the SL2-15 outage inspection.
This review determined that one other incomplete r:tating probe test resulted in a second tube (R87 L97 in SG 2B) remaining in service during Cycle 15 that was not fully evaluated by Plus Point.
Tube integrity asse3sment for both tubes and in-situ pressure testing for R100 L96 during the SL2-16 3utage, demonstrated that the defective tubes met the structural integrity and ac:ident induced leakage performance criteria of NEI 97-06, "Steam Generator Program GuLdelines." Therefore, there was no impact to the health and safety of the public.
NRC FORM 366(6-2004)
PRINTED ON REC'S'CLED PAPER NRC FORM 366 (6-2004)
PRINTED ON RECYCLED PAPERU.S. NUCLEAR REGULATORY COMMISSION (7-2001)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET LER NUMBER (6)
PAGE (3)
NUMBER (2)
E UBR()PG 3
YEAR SEQUENTIAL REVISION St. Lucie Unit 2 05000389 NUMBER NUMBER Page 2 of 4 2006 003 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)
Description of the Event ECT consists of bobbin probe inspections for general purpose screening, and rotating probe inspections for regions where the bobbin probe is not qualified for detection of degradation (i.e.,
tubesheet region).
Therefore, the rotating probe is used to characterize bobbin indications to ensure compliance with TS SR 4.4.5.4.a.6 "Plugging or Repair Limit."
On May 6, 2006, St. Lucie Unit 2 was in Mode 6 shutdown for the SL2-16 refueling outage.
During steam generator (SG)
(EIIS: AB)
ECT testing, FPL determined that an error was made during the previous refueling SG ECT.
During the previous February 2005 SG inspection, a bobbin indication was reported at the first hot leg tube support in Row 100 Line 96 in SG 2B.
Subsequently, FPL performed a diagnostic inspection with a rotating Plus Point probe.
No defect was detected and the tube remained in service.
During the May 2006 steam generator inspection, FPL again performed a Plus Point diagnostic test after the same indication was reported during bobbin coil testing, and this time the rotating probe confirmed the presence of a defect in this tube.
A routine review of prior inspection data was completed and it was determined on May 6, 2006, that the rotating probe inspection from SL2-15 did not include the entire target location to be tested, i.e.,
eggcrate tube support, thereby missing the portion that contained the indication.
R100 L96 exceeded initial screening limits and was in-situ pressure tested to demonstrate that the structural integrity and accident induced leakage performance criteria of NEI 97-06 (Steam 3enerator Program Guidelines) were maintained.
This tube passed in-situ pressure testing without any leakage or burst.
This effectively demonstrated that the 2B SG was capable of performing its intended safety function during Cycle 15 operation.
However, the maximum depth measured during SL2-16 suggests that the indication likely exceeded the 40% plugging limit of TS 4.4.5.4.a.6 at the time of the SL2-15 inspection.
All SL2-15 rotating probe data was reviewed to ensure that the entire target location was tested where the data was used to disposition a bobbin indication as "no degradation found" (NDF).
This review determined that the SL2-15 rotating probe test for a bobbin indication in R87 L97 at the second support in SG 2B was also incomplete.
The bobbin indication was observed again at SL2-16 and a rotating probe test confirmed the indication as a crack and the tube was plugged.
Based on tube integrity assessment during the SL2-16 outage, there was no structural or leakage integrity issue associated with this tube remaining in service during Cycle 15.
The results of the data reviews show this to be an event limited to a single calibration group of data in 2005.
No additional incomplete tests were observed.
In summary, two rotating probe inspections during the SL2-15 ECT did not cover the entire target area of the tube support region, thereby missing indications identified by the bobbin probe as potential defects.
This event is considered an incomplete surveillance caused by the two incomplete rotating probe inspections of bobbin probe indications identified during SL2-15.
SNRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSIOl1 (7-2001 )
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
_NUMBER (2
LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL REVISION St. Lucie Unit 2 05000389 NUMBER NUMBER Page 3 of 4 2006 003 00 TEXT (if more space is required, use additional copies of NRC Form 366A) (17)
Cause of the Event
The cause for the incomplete inspections is that the data acquisition equipment operator did not recognize that the tube end was incorrectly located and failed to correct the situation.
The error occurred only during special interest rotating probe inspection of bobbin indications, and resulted in faulty input to the axial encoder, which determines axial position within the tube.
The error appears to be a human performance error.
The operator has several years of experience and a good performance record.
There were no known extenuating circumstances.
The data was properly collected by the same operator before and after the error occurred.
In addition, the inspection vendor does have a human performance program that is reviewed with each operator prior to each inspection.
Analysis of the Event
This event is reportable under 10 CFR 50.73 (a) (2) (i) (B) as any operation or condition prohibited by the Technical Specifications (TS).
TS 3.4.5 states that each steam generator shall be operable or restored to operable status prior to increasing Tavg above 200 degrees F.
TS Surveillance 4.4.5.0 states that each steam generator shall be demonstrated operable by performance of the required augmented in service inspection program. Contrary to TS, St. Lucie Unit 2 exceeded 200 degrees F without establishing the operability of the steam generators by surveillance requirements.
Although the in-situ pressure test performed during the Spring 2006 outage concluded that the degraded SG tube was capable of performing its safety function, the maximum depth measured during SL2-16 suggests that the indication likely exceeded the 40% plugging limit of TS 4.4.5.4.a.6 at the SL2-15 inspection.
Analysis of Safety Significance The tube at R100 L96 in SG 2B was in-situ pressure tested to demonstrate that the structural integrity and accident induced leakage performance criteria of NEI 97-06 (Steam Generator Program Guidelines) was maintained. The tube passed in-situ pressure testing without any leakage or burst. Based on tube integrity assessment during SL2-16, R87 L97 did not exceed initial tube integrity screening criteria for in-situ pressure testing, therefore, there was no structural or leakage integrity issue associated with this tube remaining in service during Cycle 15.
This effectively demonstrated that the 2B SG was capable of performing its intended safety function during Cycle 15 operation.
However, the maximum depths measured during SL2-16 suggest that the indications in these tubes likely exceeded the 40% plugging limit of TS 4.4.5.4.a.6 at the SL2-15 inspection.
Based on the satisfactory in-situ pressure testing, performance of 100% ECT during the SL2-16 outage, and subsequent process verification, FPL concludes this event had no impact on the health and safety of the public.U.S. NUCLEAR REGULATORY COMMISSION (7-2001)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET LER NUMBER (6)
PAGE (3)
YEAR SEOUENTIAL REVISION St. Lucie Unit 2 05000389 NUMBER NUMBER Page 4 of 4 2006 003 00 TEXT (If more space is required, use additional copies of NRC Form 366A) (17)
Corrective Actions
The proposed 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.
I.R100 L96 in SG 2B was in-situ pressure tested to verify that structural and leakage integrity was maintained during Cycle 15.
Tube integrity assessment for R87 L97 in SG 2B at SL2-16 verified that structural and leakage integrity was maintained during Cycle 15.
Both tubes were plugged at SL2-16 (Complete).
2.All rotating probe data was reviewed to ensure that the entire target location was tested where the data was used to disposition a bobbin indication as "no degradation found (NDF)"
during SL2-16.
No additional incomplete tests were observed (Complete).
3.Revise the FPL steam generator program procedure to capture the lessons learned from St. Lucie 2, regardless of the vendor used for future inspections, to include attributes for verification of vendor training on location of tube ends using auto-locating software, verification that FPL data analysis guidelines provide effective methods to ensure that the extent of examination is obtained for rotating probe inspection of bobbin indications, including a requirement that lead personnel review results where a bobbin indication was resolved as a NDF, and verification that vendor has a human performance program and training as part of their inspection preparations.
(08/15/06).
Similar Events
LER 50-389/1998-008-00, "Missed Technical Specification Steam Generator U Tube Inspection."
LER 50-389/2001-03-00, "Steam Generator Tube That Exceeded Plugging Criteria Remained In-Service."
Failed Components None