ML17229A367
| ML17229A367 | |
| Person / Time | |
|---|---|
| Site: | Saint Lucie  |
| Issue date: | 06/03/1997 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML17229A366 | List: |
| References | |
| GL-90-05, GL-90-5, NUDOCS 9706060353 | |
| Download: ML17229A367 (5) | |
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t UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2055&4001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RE UEST FOR RELIEF FROM ASME CODE REPAIR RE UIREMENTS FOR ASME CODE CLASS 3 INTAKE COOLING WATER PIPING FLORIDA POWER AND LIGHT COMPANY ST.
LUCIE PLANT UNI DOCKET NO. 50-389
- 1. 0 INTRODUCTION
'itle 10, Part 50, Section 55a(g) of the Code of ederal Re ulations requires nuclear power facility piping and components to'eet the applicable requirements of Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (hereafter referred as the Code).
Section XI of the Code specifies Code-acceptable repair methods for flaws that exceed Code acceptance limits in piping that is in-service.
A Code repair is required to restore the structural integrity of flawed Code piping, independent of the operational mode of the plant when the flaw is detected.
Those repairs not in compliance with Section XI of the Code are non-Code repairs.
However, the implementation of required Code (weld) repairs to ASME Code Class 1,
2 or 3 systems is often impractical for nuclear licensees since the repairs normally require an isolation of the system requiring the repair, and often a shutdown 'of the nuclear power plant.
Alternatives to Code requirements may be used by nuclear licensees when authorized by the Director of the Office of Nuclear Reactor Regulation if the proposed alternatives to the requirements are such that they are shown to provide an acceptable level of quality and safety in lieu of the Code requirements
[10 CFR 50.55a(a)(3)(i)],
or if compliance with the Code requirements would result in hardship or unusual difficulty without a compensating increase. in the level of quality and safety
[10 CFR 50.55a(a)(3)(ii)].
A licensee may also submit requests for relief from certain Code requirements when a licensee has determined that conformance with certain Code requirements is impractical for its facility f10 CFR 50.55a(g)(5)(iii)J.
Pursuant Co 10 CFR 50.55a(g)(6)(i),
the Commission will evaluate determinations of impracticality, may grant relief and may impose alternative requirements as iW determines is authorized by law.
ENCLOSURE I
9706060353 970603 PDR ADQCK 05000389 P
Generic Letter (GL) 90-05, entitled "Guidance for Performing Temporary Non-Code Repair of ASHE Code Class I, 2, and 3 Piping," dated June 15,
- 1990, provides guidance for the staff in evaluating relief requests submitted by licensees for temporary non-Code repairs of Code Class 3 piping.
The staff uses the guidance in GL 90-05 as its criteria for making its safety evaluation of relief requests for temporary non-Code repairs of Code Class 3 piping.
2.0 BACKGROUND
During a scheduled blast cleaning of the 28 intake cooling water (ICW) pump discharge line I-30"-CW-ll, Florida Power and Light Company (FPL, the licensee) identified a through wall flaw in the piping at St. Lucie Plant, Unit 2.
FPL inspection.personnel conducted visual examination and ultrasonic testing (UT) examination
'of the flawed area.
An additional wall thinning flaw was detected in close proximity of the through wall flaw.
The areas were examined and mapped and an appropriate evaluation was performed by the licensee in accordance with the guidelines of GL 90-05.
The assessment of the operability of the piping demonstrated that the piping is operable.
An augmented examination was performed in the area of the leak to look for additional flaws within 15 days of discovery.
The examination identified two additional flaws.
FPL then examined ll additional points, in the most susceptible locations, based on the root cause analysis.
The augmented examinations did not reveal any additional flaws.
FPL has installed a temporary non-Code repair on the ICW leak.
The repair meets the guidelines of GL 90-05.
It consists of a passive device installed for pressure boundary integrity, using adequate and suitable materials acceptable for system temperature and pressure.
The device is removable and does not compromise the structural integrity of the piping system and the associated supports.
The device is intended to function as a temporary non-Code repair until a Code repair is accomplished during the next scheduled Unit 2 outage, which is scheduled to start on April 14, 1997.
3.0 LICENSEE'S RELIEF RE VEST
- 3. 1 Com onents for Which Relief is Re uested ASHE Code Class 3, ICW piping I-30"-CW-ll.
3.2 Section XI Edition for St.
ucie Plant Unit 2 1989 Edition of the ASHE Code,Section XI.
3.3 ASME Section XI Code Re uirement The ASHE Code Section XI requires that repairs or replacements of ASHE Code Class components be performed in accordance with rules found.in Articles IWA-4000 or IWA-7000, respectively.
The intent of these rules serves to provide an acceptable means of restoring the structural integrity of a degraded Code Class'ystem back to the original design requirements.
3:4 Content of the Relief Re uest Relief is sought from performing a repair or replacement of ICW piping, pump discharge line I-30"-CW-ll per the requirements of Article IWA-4000 or IWA-7000, respectively.
Relief is being sought until the next St. Lucie-2 scheduled outage which is scheduled to start on April 14, 1997.
3.5 Basis for Relief Request for relief has been submitted and an alternative has been proposed under the provisions of 10 CFR 50.55a(a)(3)(ii).
The licensee has stated that the leakage has been eliminated by the installation of an engineered leak repair device.
The device is a passive device installed for pressure boundary integrity only, uses adequate and suitable materials acceptable for system temperature and pressure, is removable and does not compromise the structural integrity of the piping system and its associated supports.
In addition, provisions were included in the safety evaluation to qualitatively assess the integrity of the leak limiting device by visual inspection on a weekly basis.
The provisions of GL 90-05 for. nondestructive examination assessment by UT or radiographic testing (RT) examination of the non-Code repair will not be performed because Unit 2 Cycle 10 outage will occur before the specified 3-month interval has elapsed, at which time the appropriate Code repair will be made.
- Further, the licensee has determined that a Code repair is not practical at this time.
In order to perform the Code repair, the affected headers will have to be repaired within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
The allowed outage time (72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />) may be insufficient to accomplish a Code repair which will necessitate a plant shutdown.
3.6 Licensee's Alternative Pro ram 3.6.I The licensee has stopped the leak by performing a temporary non-Code repair of the leaking area using a passive device utilizing adequate and suitable materials acceptable for system temperature and pressure.
It is removable and does not compromise the structural integrity of the piping system and its associated supports.
The temporary non-Code repair will remain in place until a Code repair or replacement is completed during the next refueling outage (which began April 14, 1997).
3.6.2 Honitoring of the degraded area by performing visual examinations on a
weekly basis.
3.6.3 Code repair of the affected piping during the next refueling outage (which began on April 14, 1997).
4.0 STAFF EVALUATION AND CONCLUSIONS 4.1 0 er abilit Determination Root Cause Anal sis and Structural Inte rit Evaluation The licensee identified a leak on the 2B ICW pump discharge line I-30"-CW-ll at St. Lucie Plant, Unit 2.
FPL inspection personnel conducted visual
examination and UT examination of the flawed area.
An additional wall thinning flaw was detected in close proximity of the through wall flaw.
The areas were examined and mapped and an appropriate evaluation was performed by the licensee in accordance with the guidelines of GL 90-05.
The assessment of the operability of the piping demonstrated that the piping is operable.
An augmented examination was performed in the area of the leak to look for additional flaws within 15 days of discovery.
The examination identified two additional flaws.
FPL then examined 11 additional points, in the most susceptible locations, based on the root cause analysis.
The augmented examinations did not reveal any additional flaws.
FPL has installed a
temporary non-Code repair on the ICW leak.
The repair meets the guidelines of GL 90-05.
It consists of a passive device installed for pressure boundary integrity, using adequate and suitable materials acceptable for system temperature and pressure.'he device is removable and does not compromise the structural integrity of the piping system and the associated supports.
The device is intended to function as a temporary non-Code repair until a Code repair is accomplished during the next scheduled Unit 2 outage, which started on April 14, 1997.
4.2 u mented Ins ection The leak was located on the pump discharge line I-30"-CW-II of the ICW piping.
An augmented examination was performed in the area of the leak to look for additional flaws within 15 days of discovery.
The examination identified two additional flaws.
FPL then examined ll additional points, in the most susceptible locations, based on the root cause analysis.
The augmented examinations did not reveal any additional flaws.
The licensee has installed a temporary non-Code repair on the ICW leak.
4.3 Pro osed Tem orar Non-Code Re air and Monitorin Provisions The licensee has stopped the leak by performing a temporary non-Code repair of the leaking area using a passive device and utilizing adequate and suitable materials acceptable for system temperature and pressure.
It is removable and does not compromise the structural integrity of the piping system and its associated supports.
The temporary non-Code repair will remain in place until a Code repair or replacement is completed during the next refueling outage, which started on April 14, 1997.
4.4 Staff Co c usions The staff has determined that the licensee's flaw evaluation has been consistent with the guidelines and acceptance criteria of GL 90-05.
The staff therefore finds the licensee's structural integrity and operability assessments to be acceptable.
The licensee has performed a non-Code repair of the leaking area using a passive device and utilizing suitable materials acceptable for system temperature and pressure.
The temporary non-Code repair will remain in place until a Code repair or replacement is completed during the next refueling outage.
The degraded area is monitored by plant operators.
Code repair or replacement will be completed during the next refueling outage (which began on April 14, 1997).
Furthermore, the staff finds that performance of an immediate Code repair would constitute an undue burden (create undue hardship) upon the licensee since the repair time most likely would exceed the Technical Specification allowed outage time (72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />) which will necessitate a Unit shutdown.
Shutting the Unit down is not in the best interest of plant safety, given the magnitude of the flaw and the licensee's alternative program.
The staff, therefore, concludes that author ization of the licensee's alternative program would provide an acceptable level of quality or safety, is authorized by law and will not endanger life or property or the common defense and security, and is otherwise in the public interest, giving due consideration to the burden upon the licensee and facility that could result if the Code requirements were imposed on the facility.
Pursuant to 10 CFR 50.55a(a)(3)(ii) the alternative is authorized until the.next scheduled outage exceeding 30 days, but no later than the next refueling outage.
At that time a Code repair will be performed.
Principal Contributor:
G. Georgiev Dated:
brune 3, 1997