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{{Adams
#REDIRECT [[L-2014-280, LER 14-001-00 for Lucie, Unit 2 Regarding Unit Shutdown Due to Leak on Safety Injection Tank Vent Valve Piping]]
| number = ML14280A480
| issue date = 09/22/2014
| title = LER 14-001-00 for Lucie, Unit 2 Regarding Unit Shutdown Due to Leak on Safety Injection Tank Vent Valve Piping
| author name = Jensen J
| author affiliation = Florida Power & Light Co
| addressee name =
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000389
| license number = NPF-016
| contact person =
| case reference number = L-2014-280
| document report number = LER 14-001-00
| document type = Letter, Licensee Event Report (LER)
| page count = 4
}}
 
=Text=
{{#Wiki_filter:FPL.September 22, 2014L-20'4-280 10 CFR 50.73U. S. Nuclear Regulatory Commission Attn: Document Control DeskWashington, D.C. 20555Re: St, Lucie Unit 2Docket No. 50-389Reporaeble Event: 2014-001Date of Event: July 25, 2014Unit Shutdown Due to Leak on Safety Injection Tank Vent Valve PipingThe attached Licensee Event Report 2014-001 is being submitted pursuant to the requirements of10 CFR 50.73 to provide notification of the subject event.Respectfully, Joeh ensen(Ar c)Site Vice President St. Lucie PlantJJ/lrbAttachment Florida Power & Light Company P2-6501 S. Ocean Drive, Jensen Beach, FL 34957 NRC FOI'M 366 U.S. NUCLEAR REGULATORY COMMISSION APPROXT[D BY OMB: NO. 3150-0104 EXPIRE,7:
01131/2017 (0)2014)
-Estimated burden per response to comply with this mandatory collection request:
80 hours./ ,
lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the FOIA, Pivacy and Information Collections
.." LICENSEE EVENT REPORT LER) Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or byL N internet e-mail to Infocollects.ResourcsOnrc.gov, and to the Desk Officer, Office of Information and(See Page 2 for required number of .Regulatory
: Affairs, NEOB-10202, (3150-0104),
Office of Management and Budget, Washington, DCfor each block) 20503. If a means used to impose an information collecton does not display a currently valid OMBdigits/characters control number, the NRC may not conduct or sponsor, and a person is not required to respond to,the information collection.
: 1. FACILITY NAME 2. LOCKET NUMBER 3. PAGESt. Lucie Unit 2 05000389 1 OF 34. TITLEUnit Shutdown Due to Leak on Safety Injection Tank Vent v'alve Piping5. EVENT DATE 6. LER NUMBER 7. REPORT DATE R. OTHER FACILITIES INVOLVEDI SE1UENTIAL REV FACILITY NAME I DOCKET NUMBERNUMBER NO .ONTH DAY YEARFACILITY NAME DOCKET NUMBER9. OPERATING MODE 11. THIS REPORT IS SUBMITTED PURSUANT TO rHE REQUIREMENTS OF 10 CFR §: (Check all that apply)D 20.220'.(b)
[ 20.2203(a)(3)(i) j 50.73(a)(2)(i)(C)
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LI 50.36(c)(1)(i)(A)
LI 50.73(a)(2)(iii)
LI 50.73(a)(2)(ix)(A)
: 10. POWER LEVEL LI 20.2203(a)(2)(i0)
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SpecifinAbstraol booor in____________________
NRC Form 366A12. LICENSEE CONTACT FOR THIS LERLICENSEE CONTACT TELEPHONE NUMBER (include Area Code)Lyle R. Berry, Licensing Engineer (772) 467-768013. COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORTI MANU- REPORTABLE LCAUSE SYgTEM COP4N'aCUE T PX~ CAU SE SYSTE MANU- REPORTABLE B BQ PSF Y14. SUPPLEMENTAL REPORT EXPECTED 15.SEXPECTED MONTH DAY YEARSUBMISSIONU LI YES (If yes, complete
: 15. EXPECTED SUBMISSION DATE) NO DATEABSTRACT (Limit to 1400 spaces, i.e., approximately 15 single-spaced typewritten lines)On July 25, 2014 with St. Lucie Unit 2 in Mode 1 at 100% power, a leak was confirmed on a one inch pipe between asafety injection tank (SIT) and a discharge header vent valve. In accordance with Technical Specifications (TS) and plantprocedures, operators subsequently shut down the unit to repair the leak. The shutdown was uncomplicated and all plantsafety systems functioned as designed.
The leaking vent line and valve assembly were replaced and returned to serviceon July 28, 2014.Engineering evaluation identified the direct cause of the pipe leak as through-wall cracking from high cycle, low stressfatigue.
This condition is reportable in accordance with the following requirements:
: 1) 10 CFR 50.73(a)(2)(ii)(A),
: 2) 10 CFR50.73(a)(2)(i)A, and 3) 10 CFR 50.73(a)(2)(i)B.
The safety significance of this event was minimal.
The identified leakage flow rate was determined to be less than 1 gallonper minute (gpm). The SIT discharge and the high pressure safety injection flow rates remained capable of satisfying theirdesign requirements during loss of coolant accident (LOCA) events.
SIRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES:
01/311201714)k.-2014) o, Estimated burden per response to comply with this mandatory collection request:
80 hours.Reported lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by......LICENSEE EVENT REPORT (LER) internet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory
: Affairs, NEOB-10202, (3150-0104),
Office of Management and Budcet,CONTINUATION SHEET Washington, DC 20503. If a means used to impose an information collecton does not display acurrently valid OMB control number, the NRC may not conduct or sponsor, and a person is notrequired to respond to, the information collection.
: 1. FACILITY NAME 2. DOCKET 6. LER NUMBER 3. PAGEYEAR SEQUENTIAL REVYEAR NUMBER NO.St. Lucie Unit 2 05000389 2 OF 32014 001 00NARRATIVE Description of the EventBackground On March 17, 2014 Unit 2 2B1 safety injection tank (SIT) (EIIS:TK) discharge piping vent valve V3811(EIIS:VTV) was replaced during the SL2-21 refueling outage. On June 22, 2014, the control room entered theProcess Radiation Monitor Abnormal Operating Procedure, due to a rising trend on two containment particulate radiation monitors.
Concurrently, plant data showed that 2B1 SIT was being filled daily beginning June 22,2014. The frequent SIT replenishment requirement and radiation monitor trend was indicative of a leak.Containment entries were made on June 24 and 25, 2014 and on July 23 and 25, 2014 to investigate thesuspected leak from the 2B1 SIT piping.On July 25, 2014 at 1129 EDT, detailed video imaging confirmed the leak was on a one inch pipe (EIIS: PSF)between the safety injection system (EIIS:BQ)
SIT and vent valve V381 1. The valve is within the Quality GroupA (ASME Class 1 equivalent),
Seismic Class I portion of the safety injection line. The applicable Technical Specification Limiting Condition of Operation (LCO) required the SIT to be restored to operable status within 24hours or shut down to Mode 3 within the next 6 hours with continuation to Mode 4 within the following 6 hours.The unit was subsequently shut down to repair the leak. The shutdown was uncomplicated and all plant safetysystems functioned as designed.
The cracked vent line and valve assembly were replaced and returned toservice on July 28, 2014.Cause of the EventA root cause evaluation team for the SI pipe break determined that the repair and replacement of vent valveV3811 was not performed as prescribed in the work control documents utilized by plant maintenance.
Thisresulted in a number of adverse factors which ultimately resulted in the failure of the pipe nipple upstream of thevent valve due to outside diameter initiated, high cycle, low stress fatigue.A contributing cause was that neither Maintenance nor the non-destructive examination (NDE) Inspector verifiedthe dimensions of the field-cut inlet pipe nipple before the vent valve was welded in as required by procedures.
Analysis of the EventFor the purposes of evaluating impact on the effected
: systems, the flaw was conservatively considered to havefully failed, resulting in a nominal one (1) inch diameter breach in the safety injection header at the location ofthe flaw. A one (1) inch breach, at this location, would result in a depressurization of the 2B1 SIT and loss ofinventory from the tank. As a result, the affected SIT was declared Inoperable.
The affected safety injection header is one (1) of the four (4) cold leg injection points for the high pressure safety injection (HPSI) system.Flow from the two HPSI Pumps combines upstream of the postulated breach and flows into the affected coldleg. Given that the postulated breach was relatively small when compared to the twelve (12) inch diametersafety injection header and the capacity of HPSI system, the HPSI system would have been able to deliversufficient flow to the reactor core, under accident conditions, to meet its safety-related functions.
NRC FORM 366A (02-2014)
P.RC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION
&.2014) LICENSEE EVENT REPORT (LER)CONTINUATION SHEET1. FACILITY NAME 2. DOCKET 6. LER NUMBER 3. PAGEYEAR SEQUENTIAL REVY NUMBER NO.St. Lucie Unit 2 05000389 3 OF 32014 001 00NARRATIVE Safety Significance The identified leakage was determined to be less than 1 gpm. This flow rate is insignificant as compared toeither the SIT discharge flowrate or the safety injection flow rate during LOCA events. Also, the SIT tankvolume lost during a four hour station blackout (SBO) event is insignificant compared to the total volume of thefour SIT's. As a result, the safety significance of the minor leakage from this location was minimal.
In addition, the branch line for the vent valve contained a tie-back support which would act to restrain the valve and piping inplace in the event the through-wall flaw continued to propagate.
: Finally, the impact of the leakage onsurrounding equipment did not reduce their ability to perform their design functions.
This condition is reportable in accordance with the following requirements:
: 1) 10 CFR 50.73(a)(2)(ii)(A),
: 2) 10CFR 50.73(a)(2)(i)A, and 3) 10 CFR 50.73(a)(2)(i)B.
Corrective Actions1. The "Weld Coordinator" software program will be modified to include hold points in weld travelers for dimension verification.
For Class 1, 2 and 3 piping and Pipe Category 4 and 5 (NNS, high pressure),
the non-destructive examination inspector will verify piping dimensions.
: 2. Welding work control procedures will be revised to ensure that the applicable weld travelers incorporate therequirement to use NDE procedure 4.10 "Component, Support & Inspection ASME Section III and ANSI B31.1Butt and Fillet Welds Visual Examination" and that the procedure is clearly designated as a corrective action toprevent recurrence (CAPR).3. Maintenance continuing training will be revised to emphasize the findings of the root cause evaluation, theimpact to the plant of this event, the importance of using human performance tools when complying with workdocuments, and the importance of ensuring that condition reports are addressed by the appropriate workdocument.
Similar EventsThe failure of a Unit 2 main steam antenna type vent line MS-11-1 occurred at approximately 2355 on 5/15/11.The one inch steam line vent MS-i 1-1 appeared to have broken off, creating a steam leak that was non-isolable without closing the main steam isolation valves (MSIVs).
An inspection of the failed vent revealed it did notmeet the design dimensions on the installation work order. During subsequent Unit 2 main steam walkdowns another vent line, MS-8-4, was found to have been installed without meeting design dimensions.
Two highenergy vent lines were not installed in accordance with the approved plant design; one of these linessubsequently failed resulting in a plant shutdown.
The root cause was that the installation of the vent line wasnot performed as prescribed in the work control documents utilized by plant maintenance.}}

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