ML17341B665

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LER 82-011/03L-0:on 820802,oil Leak on Fuel Oil Supply Manifold Discovered on Diesel Fire Pump.Caused by Defective Braze Joint.Leak Repaired by Manufacturer
ML17341B665
Person / Time
Site: Nine Mile Point Constellation icon.png
Issue date: 08/05/1982
From: Galazzo S
NIAGARA MOHAWK POWER CORP.
To:
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML17341B666 List:
References
LER-82-011-03L, LER-82-11-3L, NUDOCS 8208200112
Download: ML17341B665 (3)


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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REGARDING A RE UEST FOR RELIEF FROM ASME CODE REPAIR RE UIREMENTS FOR ASME CODE CLASS 2 PIPING FLORIDA POWER AND LIGHT COMPANY TURKEY POINT NUCLEAR PLANT UNIT 4 DOCKET NO. 50-251 I. BACKGROUND Tem orar Non-Code Re air s 10 CFR 50.55a(g) requires that nuclear facility pi'ping and components meet applicable requirements of Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (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 required Code repair may be impractical for a flaw detected during plant operation unless the facility is shut down. Pursuant to 10 CFR 50.55a(g) if (5)(iii), the licensee determines that conformance with certain Code requirements is impractical for his facility, information shall be submitted to the Commission in support of that determination and a request made for relief from the Code requirement. The Commission may grant relief based on 10 CFR 50.55a(a)(3), which states that alternatives to the requirements of paragraph (g) may be used if: (1) the proposed alternatives would provide an acceptable level of quality and safety, or (2) compliance with the specified requirements would result in hardship or unusual difficulties without a compensating increase in the level of quality and safety.

Licensee's Relief Re uest By letter dated June 26, 1992, as revised July 9, 1992, Florida Power and Light Company (the licensee) requested relief from the Code repair requirements of certain Code Class 2 piping at Turkey Point Unit 4. The licensee found a through-wall pinhole leak at the toe of the weld on a pipe elbow of a I/2 inch main steam drain line on the 4A steam header upstream of the main steam isolation valve. In its letter of July 9, 1992, the licensee, pursuant to 10 CFR 50.55a(g)(5)(iii), submitted information in support of its determination that conformance with certain Code requirements is impractical for its facility. The licensee has determined that the leak location in the 9208200112 9208l3 OSOOO2S1.

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drain line is unisolable, subject to full steam pressure during plant operation and, therefore, a Code repair would be impractical without bringing the plant to a cold shutdown. The licensee proposes to implement a temporary non-Code repair consisting of an engineered mechanical clamp secured on the leaking elbow. A permanent Code repair will be implemented during the first outage following the next Unit 4 entry into Hode 5 and no later than the next refueling outage currently scheduled for Harch 1993.

2.0 EVALUATION OF RELIEF RE VEST Code Re uirements Articles IWA/IWC-4000 and IWA/IWC-7000 provide requirements for the repair or replacement of ASHE Code Class 2 pressure retaining components with defects exceeding the acceptance standards of ASHE Section XI, Article IWA-3000.

Code Relief Re uest Relief is requested from performing a Code repair for the flaw detected during plant operation in Code Class 2 piping.

Basis For Relief Code repair requirements would result in a hardship since the piping in question cannot be isolated and such repairs are not possible unless the facility is brought to cold shutdown.

Pro osed Alternative The licensee proposes to implement a temporary non-Code repair consisting of an engineered mechanical clamp secured on the leaking elbow while the Unit is in power operation. The engineered clamp, consisting of two halves bolted together, is designed to ASHE Code Section VIII requirements and assumes that the flaw is completely through the wall for the entire pipe circumference at the location of the flaw. The clamp is capable of maintaining the integrity of the pipe should it experience a circumferential break and is designed to maintain pressure integrity and to perform the load bearing requirements of the steam drain piping system (1085 psig at 600 degrees F design) under all operating conditions. The clamp design has been verified to have no adverse impact on the existing analyses of the drain pipe or the main steam line. The licensee will develop installation procedures to preclude excessive loading on the pipe and to provide adequate precautions to minimize hazards to plant personnel safety. In addition to the regular walkdown by operations personnel once per shift, the clamp area will also be visually inspected by an engineer at least once per day. A permanent Code repair will be implemented during the first outage following the next Unit 4 entry into Hode 5 and no later than the next refueling outage currently scheduled for Harch 1993.

Staff Evaluation The staff has evaluated the licensee's submittal and concurs that Code repair requirements in this case would result in a hardship to the licensee.

Repairing the pipe in conformance with Code requirements will require bringing the plant to cold shutdown (Node 5), which may cause unnecessary cycling of the plant safety systems and components without a significant compensating gain in safety and reliability. The licensee has demonstrated that, until the next outage, the proposed temporary mechanical clamp will maintain the structural integrity of the piping system on which it is installed when subjected to design basis loading conditions and that the public health and safety will be protected. The staff finds this acceptable.

The staff has determined that the licensee has met both criteria of 10 CFR 50.55a(a)(3) and has demonstrated that the proposed alternative would provide an acceptable level of quality and safety and that compliance with the Code requirement would result in hardship or unusual difficulties without a compensating increase in the level of quality and safety.

The licensee has committed to develop installation procedures to preclude excessive loading on the piping and to provide adequate precautions to minimize hazards to plant personnel. In addition to the regular walkdown by operations personnel once per shift, the clamp assembly area will be visually inspected by an engineer at least once per day until the pipe is repaired per Code requirements. The staff finds this acceptable.

In addition, the staff recognizes that this case is unique due to, among other things, the size, geometry, and visible location of the pipe. In addition, this area is regularly walked down by the operations personnel.

3. 0 CONCLUSION Based on the above, the staff has determined that, pursuant to 10 CFR 50.55a(a)(3), compliance with the Code requirement would result in a hardship or unusual difficulty for the licensee without a compensating increase in the level of quality and safety, and that the alternatives proposed by the licensee provide an acceptable level of quality and safety. Therefore, temporary relief is granted until the first outage following the next Unit 4 entry into Node 5 and no later than the next refueling outage currently scheduled for Narch 1993. The flawed pipe must then be repaired or replaced in accordance with the Code.

Principal Contributor: L. Raghavan Date: August 13, 1992