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0313233343536373839404142433. Discussion of Standards Development Organizations(SDO) and relevant documentsThis section discusses those SDOs that are referenced in NRC documents, or that shouldbe referenced. A list of issues that should be resolved by the SDOs is presented and commentedupon. This list can be used by the SDO to address concerns that identify potential barriers to theconstruction of a nuclear power plant.To ensure that the recommendations in this report are clearly stated a uniform format wasadopted. Each recommendation will be structured as much as possible in the following way:Titlea) Status todayb) What needs to be changed for application to a nuclear power plant?c) Why does it need to be changed? Provide a rational for the change with a reference orexample3.1.American Concrete Institute (ACI)A nuclear power plant is a facility consisting of multiple structures, the reactor buildingand various other structures including emergency power, control, spent fuel and nuclear wastestorage and fuel handling buildings. Some of the non-safety related buildings are designed usingACI 318, and safety-related buildings use ACI 349 or 359. Because all three codes can each beimplemented at one site, they should maintain a level of consistency to ensure safe, durable, andeconomical construction.The American Concrete Institute (ACI) produces numerous documents related toconcrete technology. ACI Committee 318 develops a code, ACI 318, that provides minimumdesign and construction requirements for buildings. ACI has two committees specifically relatedto nuclear construction: ACI Committee 349 (Concrete Nuclear Structures) and ACI Committee359 (Concrete Components for Nuclear Reactors). ACI Committee 349 has developed “CodeRequirements for Nuclear Safety-Related Concrete Structures (ACI 349-06) and Commentary.”ACI Committee 359 is a joint committee between ACI and ASME. ASME is the controllingSDO in the partnership. This joint committee has developed the “Code for ConcreteContainments – Rules for Construction of Nuclear Facility Components (ACI 359-07)” which isSection III Division 2 of the 2007 ASME Boiler and Pressure Vessel Code. ACI 349, and to alesser extent, ACI 359 are based on modifications of ACI 318; they clearly state thecircumstances where ACI 318 is not applicable.Other ACI standards are used to design nuclear power plants and need to be maintained (seeSection 3.1.2). Another issue that was identified is that ACI needs to training and trainingcertification for technicians specifically for NPP (see section 3.1.3)In the following subsections, specific recommendations are made related to ACI 349, 359and 318 and other ACI documents.Report-v26 – February 22, 2011 – Final Draft - Submitted to NESCC7

123456789103.1.1. Recommendations for ACI 318, 349, and 359Coordination needed among ACI 318, 349 and 359 documentsIt is strongly recommended that concrete design requirements and construction provisionsbetween ACI 318, 349 and 359 should be consistent. Where construction provisions must differdue to change in safety levels, the provision, or commentary should clearly identify the change inrequirement. The following list of recommendations was developed by the CTG over the courseof several meetings. The scope is not to give a full developed solution but just a starting point forfuture implementation. Harmonize the minimum reinforcement for base mats.111213a) ACI 318, 349 and 359 have different requirements that apply to base mats. ACI318 requires a minimum reinforcement area fraction of 0.0018 that is consideredexcessive for the very thick base mats used in nuclear construction.14151617181920b) Rather than a flat number (that applies to all thicknesses), this should be based onbetter scientific rationale including ACI 207 for mass concrete. If strength doesnot control reinforcement in a mat foundation in a NPP, then minimumreinforcing requirements for temperature and shrinkage control need to bespecified for serviceability. Currently, designers are invoking the slab reinforcingratio from ACI 318 (i.e. ρ 0.0018), which can produce excessive amounts ofreinforcing for thicker mats.21222324c) In order to make the reinforcement more reasonable for thick mats and reduceunnecessary congestion. Serviceability reinforcement ratio minimumrequirements for mats in NPP structures would be helpful and promote moreconsistent designs.2526 Coordinate Section 9.2 of ACI 349, evaluating other possible load combinations, with theAISC N690-06 load combinations for possible adoption in the next revision of ACI 349.272829303132333435a) This comment deals with the fact that the load factors for Severe Environmental,Extreme Environmental and Abnormal load combinations in ACI 349, AISCN690 and the Standard Review Plan in NUREG-0800 are not in agreement. AISCN690 load combinations are clearly divided into 3 categories; Normal Loads (i.e.loads which have a high probability of being present during any one year of thedesign life of the facility), Severe Loads (which include those environmentalloads that have a 10-2/year probability of exceedence) and Extreme Loads (whichhave loads, both environmental and accidental, having a very low probability ofexceedence equal to or less than 10-4/year).363738b) The demand side of the code (i.e. load cases, load factors, load combinations)needs to be consistent across all of these design codes for NPP’s, since demand isnot related to the construction material.394041c) It is a reasonable expectation for a code user to be able to read consistent demandside requirements in ACI 349 or AISC N690, and hopefully someday those loadcombinations will be consistent with the Standard Review Plan in NUREG-0800.Report-v26 – February 22, 2011 – Final Draft - Submitted to NESCC8

Coordination of demand side requirements across ACI 349 and AISC N690 is agreat starting place. See Appendix B of this CTG report. The AISC N690suggested three load categories should be applied also to ACI-349 and include thechanges contained in NRC R.G. 1.142 as shown in Table B-2.12345 Inconsistencies between the three documents for seismic design678a) ACI 318/349 have separate shear provisions for walls in Chapter 11 for nonseismic and Chapter 21 for seismic loads. The two sets of procedures givedifferent capacities for the wall with the same reinforcement.91011121314151617b) Recommend that two equations (ACI 318/349 Equations (11-5) and (21-7)) andthe equation for shear walls in ASCE 43 (Eq. 4-3) be revised for consistency.Recommend establishing consistency, where possible, among the load cases, loadfactors, and load combinations listed in ACI 349 and 359. (see suggestion inAppendix B.) This recommendation will require additional research to implementand will become a long-term activity. In the short-term, CTG recommends thatACI Committee 359 identify the research needed for ASME-ACI to move to astrength design for reinforced concrete containment design, similar to the currentACI design methodology.181920212223c) Because with new plant concepts involve a common base mat, it is difficult todesign the containment for one set of loading and design parameters based onservice load while the rest of the CAT I structures sitting on the same base mat aredesigned for Strength level design per ACI 349. It creates a lot of interfaceissues, design issues, and unnecessary additional computation involving hundredsof load combinations.24 Design provisions for anchorage252627a) The design provisions for anchorage to concrete are almost identical in ACI 318and ACI 349. The design provisions for anchorage to concrete in ACI 359 are notwell developed and often end up defaulting to ACI 349.282930b) Recommend that the design provisions for anchorage to concrete in ACI 318 andACI 349 be harmonized to the extent possible. ACI 359 should conform to theprovisions in ACI 349.3132333435c) The provisions in ACI 349 are similar to those in ACI 318. ACI 359 on the otherhand does not have any provisions at all. Harmonizing design provisions foranchorage to concrete across ACI 318, ACI 349 and ACI 359, wherever possible,would promote commonality, reduce errors, thereby, simplify design andconstruction.36 Headed bars3738a) ACI 318-08 in section 12.6 allows headed bars which have proven to be verysuccessful in reducing congestion in nuclear construction in Europe.39b) It is recommended that ACI 349 and ACI 359 consider this change as well.4041c) It would simplify construction and significantly reduce congestions aroundanchorage points which is a real concern for ACI 349 and ACI 359 structures. ItReport-v26 – February 22, 2011 – Final Draft - Submitted to NESCC9

would also allow headed bars to be used in nuclear structures. Not doing soprevents the application of this widely used technology.12 3Coordination of updating schedule ACI 318, ACI 349, and ACI 35945a) Due to different updating schedule, the dates (versions) of referenced standardswithin each document differ.6789101112b) This means that standards for materials specifications and test methods can differbetween the documents (although aimed at the same materials), and can result indifferent requirements for materials between say the containment structure andother safety-related structures. An effort should be made to coordinate the versionof referenced standards that may be invoked on a site. This may be difficult to doin the individual codes (ACI 318, 349, and 359) because of differences in updatecycles, but should be addressed in procedures for construction specifications1314c) For example, ACI 349-06 references ASTM C150-04a for Portland cement whileACI 359-07 references ASTM C150-89. 15Durability and construction provisions in ACI 349 and ACI 35916a) The provisions in the two documents have similar, but not identical requirements.171819b) There is no reason to have different significant figures specified that can result inmisunderstandings or disputes. An effort should be made to harmonize theseunnecessary differences in requirements.20212223c) For example, ACI 349-06 permits air content to be reduced by 1.0 % for concretestrengths above 5000 psi. ACI 359-07 permits air content to be reduced by 1 %for all concretes. There are numerous other examples. ACI should establish acoordination committee that would facilitate harmonization and synchronization.2425ACI 349: Concrete Nuclear Structures26 In this section, more specific recommendations are given relative to ACI 349:ACI 349 seismic Category I structures272829a) Category I structures are designed to remain elastic, but ACI 349 retains most ofthe design and detailing provisions of Chapter 21 of ACI 318 which permitinelastic response to earthquake loads.30313233b) ACI 349-11 is expected to have details somewhat different than 318, consistentwith essentially elastic response. Perhaps intermediate details may be sufficient.Revision of this Chapter should be considered. Note that ACI 349 is currentlydiscussing revision of Chapter 21.343536c) The stringent detailing of ACI 318 is unnecessary for structures designed toremain elastic. It adds unnecessary cost to construction, schedule and createspotential concrete placement problems due to congestion.373839 Concrete mixes alloweda) Although there is much data supporting the quality of commercially availableconcrete mixes, these concrete mixes are not easily approved for use in NPP’s dueReport-v26 – February 22, 2011 – Final Draft - Submitted to NESCC10

12345to the different design requirements that are currently specified for concrete mixesto be used in NPP’s. It is believed by the concrete specifiers that many of thecommercially available concrete mixes would perform satisfactorily in NPPapplications, thereby simplifying the specification requirements and reducingoverall cost.678910b) Recommend that concrete design requirements be simplified as much as possibleto permit commercially, locally available concrete mixes to be used. Impose onlythose concrete design requirements (beyond those of ACI 318) necessary toensure the more stringent quality assurance requirements associated with nuclearsafety related construction.111213c) ACI 318 and ACI 301 requirements should be sufficient for mixture designs, butprovisions for thermal control and alkali-silica reactivity should be included fornuclear structures.14 Thermal effect151617181920212223242526272829303132333435a) Experience in structural behavior of concrete building structures subjected tonormal environmental temperature ranges (i.e. 120⁰F to -20⁰F) with erectiontemperatures between 80⁰F to 35⁰F exhibit no damage. The stresses induced bythese temperature differentials are secondary (deformation limited) in nature.Consistent with metal piping and vessel design flexibility analysis which includethermal effects analysis are generally not required for design temperatures below150⁰F. Adding the secondary normal differential temperature induced stresses toprimary stress resultants in concrete structures is an unnecessary and incorrectover conservatism because their failure modes are different. Failure due tosecondary loads is cyclic induced fatigue or ratcheting while primary load failureis caused by plastic instability. In general, fatigue ratcheting induced failures donot occur unless there are a significant number of cycles present ( 25 equivalentfull stress cycles beyond 2 times yield stress). Fatigue failure for cyclic stressesin the less than 2 times yield stress range would require 1000’s of cycles.Currently there is no minimum threshold or any discussion of an acceptableminimum threshold for thermal gradients, ΔT, or mean temperature rises, Tmean,in reinforced concrete structures under ACI 349. A rational discussion ofminimally acceptable thermal gradients, ΔT, and mean temperature rises, Tmean,has been provided in ACI 349.1R-07. Under these recommended provisions,Tmean 50 F and ΔT 100 F, would be acceptable in NPP structures withoutfurther evaluation.36373839b) Recommend that the committee consider moving thermal effect recommendationsfrom ACI 349.1R-07 into ACI 349, Appendix E, i.e. limits for acceptance withoutfurther temperature evaluation on ΔT 100 F. See Appendix C for furtherdiscussion on this issue and how ACI 349 has responded.404142c) To clarify to both licensee and the NRC that it is OK to do this - otherwise thelanguage is considered to be weak and raises a lot of questions needing supportingdocumentation. Under the recommended provisions of ACI 349.1R-07, Tmean Report-v26 – February 22, 2011 – Final Draft - Submitted to NESCC11

50 F and ΔT 100 F, would be acceptable in NPP structures without furtherevaluation, simplifying the evaluation of minor thermal effects.123 Starter mixes design in congested areas4a) The starter mix design is not allowed in ACI 318 and ACI 359/ASME.567b) ACI Committee 301, instead of ACI Committee 349 (section 5.10.9), shoulddetermine the starter mix design in situations of congestion. Recommend thatACI 349 remove starter mix design provision and refer to ACI 301.89101112c) Specification of a starter mix is a material specification requirement, which isbetter aligned with the scope of ACI 301 versus ACI 349. Consolidating materialspecification requirements into ACI 301 prevents unnecessary duplication ofmaterial requirements and reduces the potential for conflicting materialspecifications in ACI 349.13 Design Requirements for Seismic Category I1415a) No design requirements currently exist for Seismic Category I liquid containingstructures.161718b) It was recommended that a Task Group from ACI Committee 349 be establishedto coordinate with Committee 350 members to develop such design requirementsin ACI 349.19202122232425262728c) Spent fuel pools are the major example of a Seismic Category I liquid containingstructures in a NPP. ACI 350 provides a rational methodology for calculatingimpulsive and convective hydrodynamic force components due to the sloshingeffect of the liquid. However, the seismic requirements that have beenincorporated into ACI 350 come from ASCE 7, not US NRC RegulatoryGuidance, which is required of spent fuel pools in NPP’s. Therefore, it would behelpful to have seismic design requirements, consistent with US NRC RegulatoryGuidance, and industry accepted hydrodynamic force calculation methodologies,incorporated into ACI 349 to form a consistent design basis for Seismic CategoryI liquid containing structures for NPP’s.29303132ACI 359: Concrete Components for Nuclear ReactorsIn this section, more specific recommendations are given relative to ACI Committee 359: Containment liner erection tolerances33a) Containment liner erection tolerances are very generous.3435b) ASME Section III, Division 1, NE-4221.1; Division 2, CC-4522.1.1 and nonmandatory Appendix D needs to be revisited.36373839c) Since the steel liner and reinforced concrete of NPP containments form acomposite structure, their construction tolerances need to be coordinated, withconsideration given to the design of both the steel liner and reinforced concreteshell.Report-v26 – February 22, 2011 – Final Draft - Submitted to NESCC12

1 Design for impulse and impactive loads234a) ACI 359 does not provide much guidance for design for impulse and impactiveloads. The relevant NRC document is NRC DG 1176, “Guidance for theAssessment of Beyond-Design-Basis Aircraft Impacts”5678b) Rec

The American Concrete Institute (ACI) produces numerous documents related to concrete technology. ACI Committee 318 develops a code, ACI 318, that provides minimum design and construction requirements for buildings. ACI has two committees specifically related to nuclear construction: ACI Committee 349 (Concre