Regulatory Guide 1.26

Quality Group Classifications and Standards for Water-, Steam-, and Radioactive-Waste-Containing Components of Nuclear Power Plants

ML13038A086
Person / Time
Issue date:	09/30/1974
From:	US Atomic Energy Commission (AEC)
To:
References
RG-1.026, Rev. 1
Download: ML13038A086 (3)

iVgGY C0 Revision 1.U.S. ATOMIC ENERGY COMMISSION September 1974REGULATORY GUIDEqrrs "i DIRECTORATE OF R EGULATORY STANDARDSREGULATORY GUIDE 1.26QUALITY GROUP CLASSIFICATIONS AND STANDARDS FOR WATER-, STEAM-, ANDRADIOACTIVE-WASTE-CONTAIN ING COMPONENTS OF NUCLEAR POWER PLANTS

A. INTRODUCTION

General Design Criterion 1, "Quality Standards andRecords," of Appendix A, "General Design Criteria forNuclear Power Plants," to 10 CFR Part 50, "Licensingof Production and Utilization Facilities," requires thatstructures, systems, and components important to safetybe designed, fabricated, erected, and tested to qualitystandards commensurate with the importance of thesafety functions to be performed. Section 50.55a,"Codes and Standards," of 10 CFR Part 50 requires thatcomponents of the reactor coolant pressure boundary bedesigned, fabricated, erected, and tested in accordancewith the requirements for Class 1 components ofSection III of the ASME Boiler and Pressure Vessel Codeor equivalent quality standards. This guide describes aquality classification system related to specified nationalstandards that may be used to determine qualitystandards acceptable to the Regulatory staff for satis-fying General Design Criterion I for other safety-relatedcomponents containing 'radioactive material, water, orsteam in water-cooled nuclear power plants.

B. DISCUSSION

After reviewing a number of applications for con-struction permits and operating licenses and after dis-cussions with representatives of professional societiesand industry, the AEC Regulatory staff has developed aquality classification system for safety-related com-ponents containing radioactive material, water, or steamin water-cooled nuclear power plants. The systemconsists of four quality groups, A through D, methodsEditions prior to 1971 of the ASME Boiler and Pressure VesselCode,Section III, "Nuclear Power Plant Components," use theterm Class A in lieu of Class 1.for assigning components to these quality groups, andthe specific quality standards applicable to each qualitygroup. The initial, portion of this system is described in§50.55a of 10 CFR Part 50, which requires thatcomponents of the reactor coolant pressure boundyry bedesigned, fabricated, erected, and tested to the highestavailable national standards; this corresponds to thequality standard required for quality Group A of theAEC system. This guide describes a method for deter-mining acceptable quality standards for the remainingsafety-related components containing radioactivematerial, water, or steam, i.e., quality Group B, C, and Dcomponents. Other systems not covered by this guide,such as instrument and service air, diesel engine and itsgenerators and auxiliary support systems, diesel fuel,emergency and normal ventilation, fuel handling, andfire protection systems using other than water, should bedesigned, fabricated, erected, and tested to qualitystandards commensurate with the safety function to beperformed.

C. REGULATORY POSITION

I. The group B quality standards given in Table I of thisguide should be applied to water- and steam-containingpressure vessels, heat exchangers (other than turbinesand condensers), storage tanks, piping, pumps, andvalves that are either part of the reactor coolant pressureboundary defined in §50.2(v) but excluded from therequirements of §50.55a2 pursuant to footnote 2 ofthat section or not part of the reactor coolant pressureboundary but part of:2Group A quality standards that are required for pressure-containing components of the reactor coolant pressure bound-ary are specified in Section 50.55a of 10 CFR Part 50.USAEC REGULATORY GUIDESRegulatory Guides are issued to describe and make available to the publicmethods acceptable to the AEC Regulatory staff of implementing specific parts ofthe Commission's regulations, to delineate techniques .~ed by the staff inevaluating specific problems or postulated accidents, or to provide guidance toSapplicants. Regulatory Guides are not substitutes for regulations and compliancewith them is not required. Methods and solutions different from those set out inthe guides will be acceptable if they provide a basis for the findings requisite tothe issuance or continuance of a permit or license by the Commission.Published guides will be revised periodically, as appropriate, to accommodatecomments and to reflect new information or experience.Copies of published guides may be obtained by request indicating the divisionsdesired to the US. Atomic Energy Commission, Washington. D.C. 20545,Attention: Director of Regulatory Standards. 'Comments and suggestions forimprovements in these guides are encouraged and should be sent to the Secretaryof the Commission, U.S. Atomic Energy Commission, Washington, D.C. 20545,Attention: Docketing and Service SectionThe guides are issued in the following ten broad divisions:1. Power Reactors 6. Products2. Research and Test Reactors 7. Transportation3. Fuels and Materials Facilities 8. Occupational Health4. Environmental and Siting 9. Antitrust Review5. Materials and Plant Protection 10. General a. Systems or portions of systems3 important tosafety that are designed for (1) emergency core cooling,`.2) postaccident containment heat removal, or (3) post-:cident fission product removal.b. Systems or portions of systems3 important tosafety that are designed for (1) reactor shutdown or(2) residual heat removal.c. Those portions of the steam systems of boilingwater reactors extending from the outermost contain-ment isolation valve up to but not including the turbinestop valves and connected piping up to and including thefirst valve that is either normally closed or capable ofautomatic closure during all modes of normal reactoroperation. Alternatively, for boiling water reactors con-taining a shutoff valve (in addition to the two contain-ment isolation valves) in the main steam line and in themain feedwater line, Group B quality standards shouldbe applied to those portions of the steam and feedwatersystems extending from the outermost containmentisolation valves up to and including the first valve that iseither normally closed or capable of automatic closureduring all modes of normal reactor operation.d. Those portions of the steam and feedwater sys-tems of pressurized water reactors extending from andincluding the secondary side of steam generators up toand including the outermost containmenrt isolationvalves and connected piping up to and including the firstvalve (including a safety or relief valve) that is eitheryormally closed or capable of automatic closure during\ modes of normal reactor operation.e. Systems or portions of systems3 that are connectedto the reactor coolant pressure boundary and are notcapable of being isolated from the boundary during allmodes of normal reactor operation by two valves, eachof which is either normally closed or capable ofautomatic closure.2. The group C quality standards given in Table 1 of thisguide should be applied to water-, steam-, andradioactive-waste-containing pressure vessels, heat ex-changers (other than turbines and condensers), storagetanks, piping, pumps, and valves not part of the reactorcoolant pressure boundary or included in quality GroupB but part of:a. Cooling water and auxiliary feedwater systems orportions of these systems3 important to safety that are'The system boundary includes those portions of the systemrequired to accomplish the specified safety function andconnected piping up to and including the first valve (including asafety or relief valve) that is either normally closed or capable.of automatic closure when the safety function is required.'Components in influent lines may be classified as Group Dprovided they are capable of being isolated from the reactorcoolant pressure boundary by an additional valve which hashigh leak-tight integrity.designed for (1) emergency core cooling, (2) post-accident containment heat removal, (3) postaccidentcontainment atmosphere cle,.up, or (4) residual heatremoval from the reactor and from the spent fuel storagepool (including primary and secondary cooling systems).Portions of these systems that are required for theirsafety functions and that either do not operate duringany mode of normal reactor operation or cannot betested adequately should be classified as Group B.b. Cooling water and seal water, systems or portionsof these systems3 important to safety that are designedfor functioning of components and systems important tosafety, such as reactor coolant pumps, diesels, andcontrol room.c. Systems or portions of systems3 that are connectedto the reactor coolant pressure boundary and are capableof being isolated from that boundary during all modes ofnormal reactor operation by two valves, each of which iseither normally closed or capable of automatic closure.4d. Radioactive waste treatment, handling, and dis-posal systems, except those portions of these systemswhose postulated failure would not result in conserva-tively calculated potential offsite doses that exceed 0.5rem to the whole body or its equivalent to any part ofthe body. For those systems located in Seismic CategoryI structures, only single component failures need beassumed. (However, no credit for automatic isolationfrom other components in the system or for treatmentof released material should be taken unless the isolationor treatment capability is designed to the appropriateseismic and quality group standards and can withstandloss of offsite power and a single failure of an activecomponent.) Parts of these systems beyond the pro-cessing steps (such as monitoring tanks) may be classi-fied as Group D if the plant Technical Specificationslimit inventories to levels which, if released, would notresult in conservatively calculated potential offsite dosesthat exceed 0.5 rem to the whole body or its equivalentto any part of the body.e. Other systems, not covered by items 2.a. through2.d. above, that contain or may contain radioactivematerial and whose postulated failure would result inconservatively, calculated potential offsite doses thatexceed 0.5 rem to the whole body or its equivalent toany part of the body. For those systems located inSeismic Category I structures, only single componentfailures need be assumed. (However, no credit forautomatic isolation from other components in thesystem or for treatment of released material should betaken unless the isolation or treatment capability isdesigned to the appropriate seismic and quality groupstandards and can withstand loss of offsite power and asingle failure of an active component,)@44.1.26-2 3. The Group D quality standards given in Table 1 ofthis guide should be applied to water- and steam-containing components not part of the reactor coolantpressure boundary or included in quality Groups B or Cbut part of systems or portions of systems that containor may contain radioactive material.

D. IMPLEMENTATION

The purpose of this section is to provide guidance toapplicants regarding implementation of the qualitygroup classifications and standards described in SectionC of this guide.1. The quality group classifications and standardsdescribed in Section C of this guide for quality GroupsB, C, and D' should be applied to the appropriatesystems and components of all plants for which thedocket date of the application for construction permit issubsequent to January 1, 1975.2. The quality group ,classifications and standardsdescribed in Section C of this guide may be applied, atthe designer's option, to systems and components ofplants for which the docket date of the application isprior to January 1, 1975.3. Other methods for determining acceptable qualitystandards for systems and components not in qualityGroup A may be proposed to the Commission byapplicants and may be determined to be acceptable ifthey provide a comparable level of safety.sAcceptable standards for quality Group A components aredescribed in §50.55a of 10 CFR Part 50.TABLE 1QUALITY STANDARDSComponentsQuality B Quality C Quality DPressure Vessels ASME Boiler and Pressure ASME Boiler and Pressure ASME Boiler and PressureVessel Code,Section II I, Vessel CodeSection II I, Vessel Code,Section VIII"Nuclear Power Plant Com- "Nuclear Power Plant Coin- Division 1ponents," a, b, c Class 2 ponents," a, b, c Class 3Piping As above As above ANSI B 31.1.0 Power PipingIPumps As above As above Manufacturers standardsValves As above As above ANSI B31.1.0Atmospheric As above As above AP1-650, AWWA D 100, orStorage Tanks ANSI B 96.10-15 psig As above As above API-620Storage TanksaSee Section 50.55a for guidance with regard to the Code and Addenda to be applied.bASME Code N- symbol need not be applied.CThe specific applicability of code cases will be covered separately in other regulatory guides or in Commission regulations, where appro-priate. Applicants proposing the use of code cases not covered by guides or regulations should demonstrate that an acceptable level ofquality and safety would be achieved.1.26-3