Regulatory Guide 1.55
| ML13064A106 | |
| Person / Time | |
|---|---|
| Issue date: | 06/30/1973 |
| From: | Office of Nuclear Regulatory Research |
| To: | |
| References | |
| RG-1.055 | |
| Download: ML13064A106 (3) | |
JUNE 1973U.S. ATOMIC ENERGY COMMISSIONR EG U LATO RY'Oft 0 8 HN'U.U10EDIRECTORATE OF REGULATORY STANDARDSREGULATORY GUIDE 1.55CONCRETE PLACEMENT IN CATEGORY I STRUCTURES
A. INTRODUCTION
General Design Criterion 1, "Quality Standards andRecords," of Appendix A to 10 CFR Part 50, "GeneralDesign Criteria for Nuclear Power Plants," requires thatsturctures, systems, and components important to safetybe designed, fabricated, erected, and tested to qualitystandards commensurate with the importance of thesafety function to be performed. Appendix B to 10 CFRPart 50, "Quality Assurance Criteria for Nuclear PowerPlants and Fuel Reprocessing Plants," requires thatmeasures be established to assure design control,material control, special processes control, andinspection and test controls. Appendix B also requiresthat activities affecting quality be accomplished undersuitably controlled conditions. This guide describes someacceptable bases for implementing the aboverequirements with regard to the placement of concretein Category i structures.1 The Advisory Committee onReactor Safeguards has been consulted concerning thisguide and has concurred in the regulatory position.
B. DISCUSSION
Many standards, manuals, codes, and articles existwhich address the proper designing, handling, andplacing of concrete. Nevertheless, concrete continues tobe improperly placed in nuclear power plants, resultingin Iengthly delays and much wasted effort. In particular,the presence of numerous concrete voids which havebeen detected at or near the surfaces of nuclearcontainment bulkdings raises concern about the densityof portions of these and other concrete structures thatcannot readily be inspected. For such unaccessible areas,'Structures, systems, and components of a nuclear powerplant are designated as Category I if they are designed towithstand the effects of the Safe Shutdown Earthquake (SSE)and remain functional (see Regulatory Guide 1.29, "SeismicDesign Classification").the only method of assuring a quality concrete structureis through good planning and control of the placementof concrete and all items embedded in it.Proper planning and control require that thedesigner and the constructor be familiar with eachother's requirements. The designer should be consciousof the practicality of the design from the constructor'spoint of view, while the constructor. should recognizethe consequences of deviating from conditions specifiedby the designer. It is essential that the two parties meetat an early stage and discuss how these structures will beconstructed. Methods that seem expedient oreconomical .aW later turn out to have serious adverseconsequences.To date the standards applied to quality control ofconcrete in nuclear power plants have been based onstandards for conventional- building structures. Massconcrete standards have generally been consideredinapplicable for nuclear construction because the qualitylevel needed for each cubic yard of concrete placed morenearly approximates the quality level required forrelatively slender sections of conventional buildings.At the same time, it is necessary to recognize that inplacing deep foundation mats and thick-walledstructures or components in nuclear power plants, thereare placement problems (e.g., shrinkage and control ofheat of hydration during curing) also found in massconcrete pours. Consequently, consideration must begiven to the problems and practices of mass concretepours, that are applicable to nuclear power plantstructures.A list of standards, codes, papers, and otherreferences which are generally directed toward thequality placement of concrete is given in Appendix A ofthis guide. These documents, appropriately selected bythe user for the particular application underconsideration, provide useful guidance for the planningUSAEC REGULATORY GUIDES Copies of published guides troy be obtained by request indicating the divisionsdesired to the US. Atomic Energy Commission, Washington, D.C. 20645,Regulatory Quides we issued to describe and maike available to the -public Attention: Director of Regulatory Standerds. Comments and suggestions formethods acceptable to the AEC Regulatory staff of implementing specific parts of improvements in those guides are encouraed and should be sent to the Secretarythe Commission's regulations, to delineate techniques used by the staff in of the Commission, US. Atomic Energy Commission, Washington, D.C. 20645,etluating specific problems or postulated accidents, or to provide guidance to Attention: Chief, Public Proceedings Staff.essplimnts. Regulatory Guides are not substitutes for regulations and compliancewith them is not required. Methods and solutions different from those set out in The guides are issued in the following ten broad divisions:the guides will ta accaptable if they provide e bais for the findings requisite tothe issuensc or continuance of a permit or license by the Commission. 1. Power Reactors 6. Products2. Research and Test Reactors 7. Transportation& Fuels and Materials Facilities a. Occupetional HealthPublished guides will be revised periodically, es appropriate, to accommodate 4. Environmental and Siting 9. Antitrust Reviewcomnnts and Oto reflect new information or experience. S. Materials and Plant Protection 10. General and coordinating activities prerequisite to concreteplacement. However, the listing of these references in anappendix to this guide does not constitute a blanketendorsement of their contents.Individual material specifications (ASTM, etc.) arenot included in Appendix A of this guide, since thisguide addresses only the requirements for properplanning and coordination in placing concrete so as toavoid the recurring problems of voids, cracks, and bulgeswhich have been experienced in nuclear power plantconstruction.
C. REGULATORY POSITION
The regulatory positions given below for theapplicant, the designer, and the constructor togetherwith the guidance from appropriate documents listed inAppendix A of this guide represent a minimum basis forassuring compliance with the Commission's regulationsin Appendices A and B to Part 50 and should besupplemented as necessary in the appropriate qualityassurance programs and project specifications. (As anexample, in several areas ACI 301 lists stricter concretesampling requirements than ACI 318. In such cases, therelevant provisions of ACI 301 should govern in theinterest of obtaining the best concrete quality practicalunder existing industry practices.)1. Applicant. The applicant's quality assuranceprogram should ensure that early and regularcommunication is established between the designer andconstructor. Rapid access to the designer should bepossible for the constructor in the event that a fieldcondition requires immediate consultation with thedesigner, such as relocation of a construction joint or anembedded item while placing of concrete is in progress.Conversely, the designer should have rapid access to theconstructor in the event that late revisions must be madein the field because of changes in design. Under theprovisions of Appendix B to Part 50, the applicant'squality assurance program should also ensure theimplementation of sections C.2. and C.3. below.2. Designera. The designer should check the design and shopdrawings for practicality of:(1) Placement of reinforcing bars-continuity,congestion, interference, non-planar geometric bendingand placing requirements, splice locations and their.effect on minimum bar spacing.(2) Location of embedded items-feasibility ofplacing concrete completely around the item,considering congestion and interference from otherembedded items and reinforcing as well as the type ofconcrete to be placed (slump, aggregate size, whetherpreplaced appregate is used, etc.).(3) Locations of construction joints-locationsof acceptable construction joints should be noted, aswell as any "windows" in congested reinforcing patternsneeded for placing the concrete. Followup coordinationand revision with the constructor is essential. Factors forconsideration include: type and quantity of concrete tobe placed; shrinkage and creep; accessibility; cleanoutcapability before and after placing the concrete; andacceptability from a strength or functional point ofview. Alternative joint locations should be available tothe constructor in the event that concrete placementcannot be completed as planned and started.b. In addition to checking the drawings as notedabove, the designer should assist the constructor asnecessary in preplanning placement of reinforcement,embedded items, and concrete as well as the sequence tobe followed in placing concrete. The designer should alsofollow the construction while it is in progress, including,if necessary, occasional site visits, and be available forassistance in resolving unanticipated field placementproblems that might affect the structural or functionalintegrity of the structure. Field generated revisionsshould be approved by the designer.3. Constructor. In addition-to the coordination notedabove, preplanning by the constructor is necessary for:a. Cleanness-assuring cleanness of formed areaprior to and during concrete placement, including accessprovisions for inspection and cleanout operations.b. Installations-installations of reinforcing bars,splices, embedded items, formwork, and constructionjoint barriers should be checked prior to placingconcrete.c. Placement layout-practicality of constructionjoint locations, venting of potential air pockets toprevent voids, access to congested or confined areas,sequence of placement.d. Equipment-availability of proper equipment ingood operating condition and in sizes and quantitiesneeded (vibrators, chutes, etc.). Sufficient spares (partsor equipment) should be readily available so that loss orbreakdown of equipment will not interrupt the placingof concrete and result in unplanned cold joints.e. Personnel-sufficient training and experience inthe proper use' of all equipment (especially vibrators)involved in the placing of concrete. Also sufficientsupervisory knowledge and experience to enable theconcrete placement to be completed ih accordance withspecifications.1.55-2 APPENDIXBIBLIOGRAPHY OF USEFUL REFERENCES1. ACI 318-71 Building Code Requirements forReinforced Concrete (and Comraentary)-Chapter5, "Mixing and Placing Concrete".2. ACI 301-72 Specifications for Structural Concretefor Buildings.3. ACI 305 72 Recommended Practice for HotWeather Concreting.4. ACI 306-66 Recommended Practice for ColdWeather Concreting.5. ACI 308-71 Recommended Practice for CuringConcrete.6. ACI 347-68 Recommended Practice for ConcreteFormwork.7. ACI 614-(Proposed Revision) RecommendedPractice for Measuring, Mixing, Transporting andPlacing Concrete.8. ACI Special Publication No. 4-Formwork forConcrete.9. ACI Committee 207 "Mass Concrete for Dams andOther Structures" ACI Journal April 1970, pp.273-309.10. "Cracking Controlled in Massive, ReinforcedStructural Concrete by Application of MassConcrete Practices." L. H. Tuthill and R. H. Adams,ACI Journal August 1972, pp. 481-491.11. ACI/ASME Proposed Standard-Code for ConcreteReactor Vessels and Containments (ASME Sect. III,Division 2) CB 4200, CC 4200 and CB 4340-4370,CC 4340-4370.12. ANSI N45.2.5-1972 (proposed) SupplementaryQ.A. Requirements for Installation, Inspection, andTesting of Structural Concrete and Structural SteelDuring the Construction Phase of Nuclear PowerPlants.13. Concrete Manual, U.S. Bureau of Reclamation,Denver; Seventh Edition, 1966.14. Standard Practice for Concrete (EM 1110-2-2000);Dept. of the Army, Office of Chief of Engine rs,Washington, D.C.; November 1971.1.55-3