ACI 349.3R-18 Report on Evaluation and Repair of Existing Nuclear Safety-Related Concrete Structures

ACI 349.3R-18 Report on Evaluation and Repair of Existing Nuclear Safety-Related Concrete Structures. 1.2––Scope Chapters 1 and 3 provide the introductory material and general methodology used, respectively. Chapters 4 through 7 and Chapter 9 include new information, expanded coverage, and relevant references for continued research. Chapter 8 provides guidance on the need for repair; use of proven methods, including those recently implemented in specifc nuclear plants; and relevant industry references (ACI/ICRI 2013). To ensure that evaluations and any follow- up repairs are properly implemented, it is recommended that the responsible engineer remains in charge throughout the completion of all the tasks up to documentation, including evaluation reports and repair programs as defned herein. This report supplements the ACI 349 code by presenting a framework for conducting an evaluation and developing any associated repair procedures for nuclear safety-related concrete structures. Before initiating this report, the scope of ACI 349 was self-limited to the design and inspection of newly constructed concrete nuclear structures. As the nuclear power plants in the United States grow older and become susceptible to the adverse efects of aging, their periodic inspection, proper evaluation, and repair have become more important issues. Recent U.S. NRC regu- lations 10 CFR50.65 and 10 CFR54 (U.S. NRC 2015a,b) require licensees to inspect and evaluate the condition of concrete nuclear structures that may have experienced age- related degradation. Also, following the accident at the Fukushima Daiichi nuclear power plant resulting from the March 11, 2011, Great Tohoku Earthquake and subsequent tsunami in Japan, the NRC established the Near Term Task Force (NTTF) to conduct a review of the NRC processes and regulations, and provide recommendations to the NRC regu- latory process to enhance reactor safety. 3.2—Scope The evaluation of existing nuclear safety-related concrete structures could be required as a result of identifed degra- dation or abnormal performance, in support of physical modifcations, or for periodic validation of structural integ- rity. Comprehensive evaluation of all nuclear safety-related structures at periodic intervals is also desirable to monitor operational efects and possible degradation due to envi- ronmental conditions. This chapter describes the procedural steps that can be used to efectively monitor and maintain the nuclear safety-related concrete structures via prioritized evaluation. An evaluation procedure document should be devel- oped by the owner (3.5). The evaluation procedure should be comprehensive and include provisions for addressing the variety of potential uses, such as those cited in Chapter 1....