ML080720433

Correction Pages for Correction to Amendment Nos. 360, 362, and 361 for Oconee Nuclear Station, Units 1, 2, and 3

ML080720433
Person / Time
Site:	Oconee
Issue date:	03/26/2008
From:	Olshan L NRC/NRR/ADRO/DORL/LPLII-1
To:	Brandi Hamilton Duke Power Co
Olshan L N, NRR/DORL, 415-1419
Shared Package
ML080720409	List: ML080720414 ML080720433
References
Download: ML080720433 (2)

Text

3.0 TECHNICAL EVALUATION

The masonry walls discussed in the license amendment request (LAR) are non-structural elements, and are single and multiple wythe in-fill panels constructed of hollow or grouted concrete blocks or constructed of solid concrete bricks. The typical FRP application will consist of a matrix of fiber bonded directly to existing masonry walls with a polymer. The LAR stated that future use of FRP, as proposed, will be predicated on the satisfactory completion of qualification testing and commercial grade dedication of the selected FRP system and the incorporation of subsequent periodic surveillance requirements into existing plant programs.

The detailed design, qualification, installation and inspection, and inservice surveillance methods for the FRP system are contained in the LAR. The Nuclear Regulatory Commission (NRC) staff reviewed the licensee's proposed methods and data provided by the licensee that had been acquired from a number of industry performance tests that are relevant to the masonry walls located within the Oconee 1/2/3 auxiliary buildings. The acceptability and applicability of the licensee's methods for design, qualification, installation and inspection, and inservice surveillance are discussed below.

3.1 Applicability of the FRP System Design Method The licensee's FRP design method is only applicable to the non-structural concrete block masonry walls located in the Oconee 1/2/3 auxiliary buildings. It is not applicable to the non-structural solid brick masonry walls located in these auxiliary buildings.

3.2 The FRP System Design Method The design is based on a working stress method and assumes a one-way span behavior for masonry walls to resist the flexural stress generated by a tornado. In its October 30, 2007, response to the NRC staff's request for additional information (RAI), the licensee stated that it will limit the masonry allowable flexural compressive stress to 70 percent of the masonry compressive strength, which is intended to preclude the brittle failure mode of masonry walls.

The licensee also stated in its response to the RAI that it will comply with the NRC staff's request and limit the reinforcement index to 70 percent, which is intended to preclude the shear failure of the FRP-strengthened masonry walls. The licensee stated that the masonry allowable shear stress will be limited to 50 psi. The licensee stated that both ACI 531-79 and ACI 530-05, "Building Code Requirements for Masonry Structures," indicate an upper limit of 50 psi for masonry allowable shear stress for flexural members without shear reinforcement. The NRC staff concludes that the licensee's compliance with these limits on masonry allowable flexural compressive stress, reinforcement index, and masonry allowable shear stress will provide additional assurance that the FRP-reinforced masonry walls will withstand the uniform pressure loads resulting from a tornado. Therefore, the NRC staff concludes that the FRP System design method is acceptable. In addition, the design procedure includes a provision to evaluate the flexural stress generated due to the corner effect of masonry wall panels, and to reinforce them, if warranted.

3.3 The FRP System Qualification Method The licensee has committed that qualification tests and reporting for the selected FRP system will be performed in accordance with "Interim Criteria for Concrete and Reinforced and

Unreinforced Masonry Strengthening Using Fiber-Reinforced Polymer (FRP) Composite Systems," International Code Council (ICC) AC125, June 2003. The licensee has committed to perform and document a technical evaluation of the selected FRP system (fibers and polymeric resin) to demonstrate the following:

(1) The selected FRP system qualifies as commercial grade in accordance with Duke's Supply Chain Directive (SCD) 230, "Commercial Grade Items";

(2) The supplier is capable of supplying a quality product in accordance with SCD 230; and (3) The quality of the selected FRP system has been evaluated in accordance with ICC AC125; and, therefore, its quality can be reasonably assured.

The NRC staff concludes that the FRP system qualification method is acceptable because it complies with ICC AC125 and Duke's SCD 230.

3.4 The FRP System Installation and Inspection Method The licensee commits to use technical procedures to test the concrete masonry substrate, and to control the installation and inspection of the FRP system onto existing nasonry walls, in accordance with ICC AC125; "Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures," ACI 440.2R-02; and "Interim Criteria for Inspection and Verification of Concrete and Reinforced and Unreinforced iMasonry Strengthing Using Fiber-Reinforced Polymer (FRP) Composite Systems," ICC AC 178, July 2003.

The NRC staff concludes that the FRP system installation and inspection method is acceptable because it complies with these three standards.

3.5 The FRP System Inservice Surveillance Method The licensee's inservice inspection of the FRP system will be performed on a nominal 5-year interval, which is the standard interval defined in Duke's Engineering Directive Manual EDM-410 for monitoring and assessing the condition of civil engineering structures and components.

This inspection frequency may be reduced to a nominal 10-year interval with appropriate justification based on the structure, environment, and previous inservice inspection results. The inspection includes visual inspections for changes in color, debonding, peeling, blistering, cracking, deflection and other anomalies. The inspection also includes tension adhesion testing of cored samples using methods specified in "Standard Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers," American Society for Testing Materials (ASTM)

D4541, or "Building Code Requirements for Masonry Structures," ACI 530R-02. Records of the inservice inspection reports will be considered Quality Assurance Records in accordance withTitile 10 of the Code of FederalRegulations (10 CFR), Part 50, Appendix B,Section XVII, "Quality Assurance Records." All inspection reports will be maintained for the life of the plant.

The NRC staff concludes that the FRP system inservice surveillance method is acceptable because it complies with Duke's EDM-41 0, ASTM D4541, ACI 530R-02, and 10 CFR, Part 50, Appendix B,Section XVII.