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Regulatory Guide 1.188, Revision 1.

Regulatory Guide 1.188 [5] provides guidance to applicants on the format and content of a LRA to ensure uniformity of the format and level of technical content, and endorses NEI Guideline 95-10, Rev. 6 [8] for implementing the Rule. Conformance with the regulatory guide is not required, but its use facilitates both the applicant’s preparation of a LRA and the NRC staff’s timely and consistent review. Other formats are considered acceptable if they provide an adequate basis for approval of the application for license renewal.

Generic Aging Lessons Learned (GALL) Report.

The GALL Report lists generic AMRs of SSCs that may be in the scope of LRAs and identifies aging management programs (AMPs) that are determined to be acceptable to manage aging effects of SSCs in scope of license renewal as required by 10 CFR Part 54. The GALL Report provides a technical basis for the SRP for License Renewal and contains the NRC staff’s generic evaluation of the existing plant programs and documents the technical bases for determining where existing programs are adequate without modification and where existing programs should be augmented for the extended period of operation. Each structure and/or component is identified as well as its material(s) of construction, environment, aging effects/mechanisms, acceptable programs to manage the effects of aging, and if further evaluation is required. The adequacy of the generic AMPs in managing certain aging effects for particular structures and components is based on a review of ten program elements of an AMP for license renewal [7]: scope of program, preventative actions, parameters monitored or inspected, detection of aging effects, monitoring and trending, acceptance criteria, corrective actions, confirmation processes, administrative controls, and operating experience.

The GALL Report contains 11 chapters and an appendix [6]. Chapter I addresses application of the American Society of Mechanical Engineers (ASME) Code to license renewal. Selected sections of the ASME Code are endorsed by the NRC as incorporated in 10 CFR Part 50.55a. The NRC periodically amends 10 CFR Part 50.55a and issues Federal Register Notices about this rule in order to endorse, by reference, newer editions and ASME Code Addenda subject to the modifications and limitations identified in 10 CFR Part 50.55a. Some of the AMPs referenced in the GALL Report are based entirely or in part on compliance with the requirements of ASME Code Section XI, “Rules for Inservice Inspection of Nuclear Power Plant Components.” The staff has determined that the referenced ASME Section XI programs or requirements provide an acceptable basis for managing the effects of aging during the period of extended operation for these AMPs, except where noted and augmented in the GALL report (e.g., Section XI Subsections IWE,” Requirements for Class MC and Metallic Liners of Class MC Components of Light-Water Cooled Plants,” and IWL, “Requirements for Class CC Concrete Components of Light-Water Cooled Plants”). The licensee is required to amend its CLB by updating its ASME Section XI edition and addenda of record to the most recently endorsed edition and addenda referenced in 10 CFR Part 50.55a 1 year prior to entering the next 10-year internal inservice inspection for its unit. Chapters II through VIII contain summary descriptions and tabulations of evaluation of AMPs for a large number of structures and components in major plant systems found in light-water reactor (LWR) NPPs. Chapter IX contains definitions of a selection of standard terms used within the GALL Report. Chapter X contains the TLAA evaluation of AMPs under 10 CFR Part 54.21(c)(1)(iii). Chapter XI contains AMPs for the structures and mechanical and electrical components. The Appendix to the GALL Report addresses quality assurance for the AMPs.

Chapter II of the GALL report addresses Pressurized Water Reactor (PWR) and Boiling Water Reactor (BWR) containment structures. Safety related (e.g., BWR reactor building and PWR shield building) and other structures (e.g., containment internal structures and water-control structures) are addressed in Chapter III of the GALL Report. Pressurized Water Reactor containments are subdivided into concrete containments (reinforced and prestressed), steel components, and common components. Boiling Water Reactor containments are subdivided into Mark I containments (steel and concrete), Mark II containments (steel and concrete), Mark III containments (steel and concrete), and common components. Information provided in Chapter II, as well as Chapters III through VIII, is in a tabular format.

AMPs related to NPP containment structures are identified in Chapter XI of the GALL Report. This chapter provides a description of each of these programs as well as the evaluation and technical basis related to a review of the ten program elements of an AMP for license renewal identified in the SRP-LR [7]. AMPs related to the concrete containment include: ASME Section XI, Subsection IWL (GALL AMP XI.S2) and Structures Monitoring (GALL XI.S6). AMPs related to the post-tensioning system include: ASME Section XI, Subsection IWL (GALL AMP XI.S2) and Concrete Containment Tendon Prestress Time-Limited Aging Analysis (GALL TLAA X.S1). AMPs related to the steel containments and liners of reinforced concrete containments include: ASME Section XI, Subsection IWE (GALL AMP XI.S1), 10 CFR Part 50, Appendix J (GALL AMP XI.S4), and Containment Liner Plate, Metal Containments, and Penetrations Fatigue Analysis Time-Limited Aging Analysis. With the exception of the Structures Monitoring Program and the TLAA associated with the post-tensioning system and the containment metal components, the AMPs are discussed in Chapter 4 of the GALL report.

The Structures Monitoring AMP (XI.S6) includes all structures, structural components, component supports, and structural commodities in the scope of license renewal that are not covered by other AMPs such as noted above. The structures monitoring program consists of periodic visual inspections by personnel qualified to monitor structures and components for applicable aging effects such as noted in American Concrete Institute Standards (ACI) 349.3R [9], ACI 201.1R [10], and American National Standards Institute/American Society of Civil Engineers Standard (ANSI/ASCE) 11 [11]. In general, all structures are monitored on a frequency not to exceed 5 years, but some structures subject to benign environmental conditions, may be monitored at an interval exceeding 5 years. Identified aging effects are evaluated by qualified personnel using criteria derived from industry codes and standards contained in the plant CLB, including ACI 349.3R, ACI 318 [12], ANSI/ASCE 11, and the American Institute of Steel Construction (AISC) specifications, as applicable. Acceptance criteria are selected for each structure/aging effect to ensure that the need for corrective actions is identified before loss of intended functions. The criteria are derived from design bases codes and standards that include ACI 349.3R, ACI 318, ANSI/ASCE 11, or relevant AISC specifications, as applicable, and consider industry and plant operating experience. The structures monitoring program also addresses detection of aging effects for inaccessible below-grade concrete structural elements. Groundwater is sampled at a frequency not to exceed 5 years and for plants with non-aggressive groundwater/soil (pH > 5.5, chlorides < 500 ppm, and sulfates < 1500 ppm), the program recommends: (1) evaluating the acceptability of inaccessible areas when conditions exist in accessible areas that could indicate the presence of, or result in, degradation to such inaccessible areas; and (2) examining representative samples of exposed portions of the below grade concrete, when excavated for any reason. A plant-specific AMP, accounting for the extent of degradation experienced, should be implemented to manage aging during the period of extended operation where aggressive groundwater is present or concrete structural elements have experienced degradation.

The Concrete Containment Tendon Prestress TLAA AMP (X.S1) provides reasonable assurance of the adequacy of prestressing forces in prestressed concrete containment tendons during the period of extended operation under 10 CFR Part 54.21(c)(1)(iii). The program consists of an assessment of inspections performed in accordance with the requirements of Section XI, Subsection IWL of the ASME Code, as supplemented by the requirements of 10 CFR Part 50.55a(b)(2)(viii). The assessment related to the adequacy of the prestressing force establishes: (1) acceptance criteria in accordance with NRC Regulatory Guide 1.35.1 [13], and (2) trend lines based on the guidance provided in NRC Information Notice 99-10 [14]. The estimated and measured prestressing forces are plotted against time, and the predicted lower limit, minimum required value, and trending lines are developed for the period of extended operation. Regulatory Guide 1.35.1 provides guidance for calculating the predicted lower limit and minimum required value. The trend line represents the trend of prestressing forces based on the actual measured forces. The prestressing force is acceptable when the trend line is above the minimum required value throughout the period of extended operation. If acceptance criteria are not met, then either systematic retensioning of tendons or a reanalysis of the containment is warranted to ensure design adequacy of the containment. Appendix 5A of this chapter provides additional information related to monitoring and trending the prestressing forces in NPP post- tensioned concrete containments.

If a plant’s code of record (ASME Section III, Division 1 or Division 2) requires a fatigue analysis of the liner plate, then the analysis may be a TLAA and must be evaluated in accordance with 10 CFR Part 54.21(c)

(1) to ensure that the effects of aging on the intended functions are adequately managed for the period of extended operation. The ASME Section III fatigue analysis requires the calculation of a cumulative usage factor based on the fatigue properties of the materials and the expected fatigue service of the component. The ASME Code limits the cumulative usage factor to a value less than or equal to one for acceptable design fatigue. Three acceptance criteria for fatigue of containment liner plates are available: existing calculations remain valid because the number of assumed cyclic loads will not be exceeded during the period of extended operation; the cumulative usage factor calculations are re-evaluated based on an increased number of assumed cyclic loads to cover the period of extended operation and the new cumulative usage factor does not exceed one; and a AMP provided by the applicant demonstrates that the effects of aging on the component’s intended function(s) will be adequately managed during the period of extended operation.

 
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