Regulatory Guide 1.72: Difference between revisions

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{{Adams
{{Adams
| number = ML13038A106
| number = ML003740253
| issue date = 11/30/1978
| issue date = 11/30/1978
| title = Spray Pond Piping Made from Fiberglass-Reinforced Thermosetting Resin
| title = Spray Pond Piping Made from Fiberglass-Reinforced Thermosetting Resin
| author name =  
| author name =  
| author affiliation = NRC/RES, NRC/OSD
| author affiliation = NRC/RES
| addressee name =  
| addressee name =  
| addressee affiliation =  
| addressee affiliation =  
Line 10: Line 10:
| license number =  
| license number =  
| contact person =  
| contact person =  
| document report number = RG-1.072, Rev. 2
| document report number = RG-1.72, Rev 2
| document type = Regulatory Guide
| document type = Regulatory Guide
| page count = 7
| page count = 3
}}
}}
{{#Wiki_filter:&3&ws~stsn I Revision 2 November 1978 U.S. NUCLEAR REGULATORY  
{{#Wiki_filter:U.S. NUCLEAR REGULATORY  
COMMISSION
COMMISSION
REGULATORY  
Revision 2 November 1978 REGULATORY  
GUIDE OFFICE OF STANDARDS  
GUIDE OFFICE OF 'STANDARDS  
DEVELOPMENT
DEVELOPMENT  
REGULATORY  
REGULATORY  
GUIDE 1.72 SPRAY POND PIPING MADE FROM FIBERGLASS-REINFORCED  
GUIDE 1.72 SPRAY POND PIPING MADE FROM FIBERGLASS-REINFORCED  
Line 26: Line 26:
==A. INTRODUCTION==
==A. INTRODUCTION==
General Design Criterion  
General Design Criterion  
1, "Quality Stand-ards and Records," of Appendix A, "General Dtsign Criteria for Nuclear Power Plants," to 4' y -O CFR Part 50, "Domestic Licensing of Pro-duction and Utilization Facilities," requires that structures, systems, and components important to safety be designed, fabricated, erected, and tested to quality standards com-mensurate with the importance of the safety functions to be performed.
1, "Quality Stand ards and Records," of Appendix A, "General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50, "Domestic Licensing of Pro"-duction and Utilization Facilities," requires that structures, systems, ý and .components important  
..to safety be designed, fabricated, erected, and tested to quality standards com mensurate with the importance of the safety functions to be performed.
 
Appendix B, "Qual ity Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants," to 10 CFR Part 50 requires that measures be established to ensure materials control and control of special processes such as resin molding.
 
Section 50.55a, "Codes and Standards," of 10 CFR Part 50 requires that design, fabrica tion, installation, testing, or inspection of the specified system or component be in accordance with generally recognized codes and staridards.


Appendix B, "Qual-ity Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants," to 10 CFR Part 50 requires that measures be established to ensure materials control and control of special processes such as resin molding.Section 50.55a, "Codes and Standards," of 10 CFR Part 50 requires that design, fabrica-tion, installation, testing, or inspection of the specified system or component be in accordance with generally recognized codes and standards.
Footnote 6 to § 50.55a states that the use of specific Code Cases may be authorized by the Commission upon request pursuant to § 50.55a (a)(2)(ii), which requires that proposed alter natives to the described requirements or por tions thereof provide an acceptable, level of quality and safety.  This guide describes a method acceptable to the NRC staff for implementing these require ments with regard to the design, fabrication, and testing of fiberglass-reinforced thermo setting resin (RTR) piping for spray pond applications.


Footnote 6 to § 50.55a states that the use of specific Code Cases may be authorized by the Commission upon request pursuant to § 50.55a (a)(2)(ii), which requires that proposed alter-natives to the described requirements or por-tions thereof provide an acceptable level of quality and safety.This guide describes a method acceptable to the NRC staff for implementing these require-ments with regard to the design, fabrication, and testing of fiberglass-reinforced thermo-setting resin (RTR) piping for spray pond applications.
This guide applies to light-water cooled and gas-cooled reactors. .The Advisory Committee on Reactor Safeguards has been con sulted concerning this guide and has concurred in the regulatory position.


This guide applies to light-water- cooled and gas-cooled reactors.
*Lines indicate substantive changes tram previous issu


The Advisory Committee on Reactor Safeguards has been con-sulted concerning this guide and has concurred in the regulatory position.Lines indicate substantive changes from previous issue.
====e. USNRC REGULATORY ====
GUIDES Regulatory Guides eam issued So descilbe end make svalable ID ft publi methods acCeptable w to NRC staff al ill*em ntig apeodf pIne o .on Com 'laln rguatl Io denwte lecdn-,= wed by 1w staff in evsu~ pcfcproblems or postiletad aceldents.
 
Or ID prVOvd gJUWdnc 10 nt.Ragulatory Gulde. wre hiot subeftfts te 10"0 sauelosnd corn pence with irn Is not equkL Meihods and eolutlona dffrent rom *so s out in weidss v be = "*e thP prfdo r a *Xe&W Me e c.n aetr ka by to Corm desio Comnenwts n uggestou wo fo tr aov~ament meh 1wae idesare ncourasgdat of I m. n wgukd. .Ube ,ebed. as Pfrpiat. 10 sci10date camnme and 10 ~sic now infomato or expe-rienoe.
 
This guide was orvised ae remit of subetantie coment isev OM 111 pubic end additional emil revlew.


==B. DISCUSSION==
==B. DISCUSSION==
The ASME Boiler and Pressure Vessel Com-mittee publishes a document entitled "Code Cases."' Generally, a Code Case explains the intent of rules in the ASME's Boiler and Pressure Vessel Code (the Code)1 or provides for alternative requirements under special circumstances.
The ASME Boiler and Pressure Vessel Com mittee publishes a document entitled "Code Cases." Generally, a Code Case explains the 'intent of rules in the ASME's Boiler and Pressure Vessel Code (the Code)' or provides for alternative requirements under special circumstances.
 
Most Code Cases are evehtually Ssuperseded by Lrevisions to the Code and then are annulled by action of the ASME Council.
 
Code Case N-155-1 (1792-1), referred to in this guide, is limited to Section III, Division 1, of the Code and is oriented toward design and fabrication of RTR piping. The Code Case does not prescribe a lower temperature limit, prima rily because the American Society for Testing and Materials (ASTM) specifications do not contain a lower temperature" limit, but RTR piping systems would normally be qualified for the intended service temperature condition.
 
It is planned that after Revision 2 of, this guide is issued, the acceptability of future minor revisions to Code Case N-155 (1792) will be noted in Regulatory Guide 1.84, "Design and Fabrication Code Case Acceptability--ASME
Section III Division I1." Major revisions to the Code Case will, however, result in a revision -to this guide -(1.72). Filament-wound struc tures have mechanical properties superior to fiberglass-filled laminates, and they are con sidered more desirable when intended for safety-related pressure components.
 
The Code Case obtains an allowable design stress from the hydrostatic design basis (HDB) strength as derived from either Procedure A Copies Jay be obtained from the American Society of Mechan ticl Inghieers.
 
United Ingieerling Canter, 345 Seat 47th Street.  New Terk. New Yorkt 10017.Connffao awloid be se nt fto Ssem" of Me CommisIonS
U.S. Nucea noguitor Commission Washingon D.C. *W Attntion:
Ockstlng anO Ma e gildas ua ied in 1ft Ioowg ten bod tlona: 1. ftwr Reactors S. PoducM 2. Iosearch wed Tat Rescto


Most Code Cases are eventually superseded by revisions to the Code and then are annulled by action of the ASME Council.Code Case N-155-1 (1792-1), referred to in this guide, is limited to Section III, Division 1, of the Code and is oriented toward design and fabrication of RTR piping. The Code Case does not prescribe a lower temperature limit, prima-rily because the American Society for Testing and Materials (ASTM) specifications do not contain a lower temperature limit, but RTR piping systems would normally be qualified for the intended service temperature condition.
===7. Trsrporatn ===
3. -uek and Maltis Fact Wes .c Heath 4. gnvoniwntdl and SRing S. Antitrust ind Financial Review S. tairla end Pi P cton 10.


It is planned that after Revision 2 of this guide is issued, the acceptability of future minor revisions to Code Case N-155 (1792) will be noted in Regulatory Guide 1.84, "Design and Fabrication Code Case Acceptability--ASME
Request for singe coples of lasued Suides lutch nay be uspaoduedl for f placement en en automat dalbutlon Ist fo g o f at u.gd In specfick dvimsn etmiod be wadle hInwm an7le UMSNuclarReulaimy Comission.
Section III Division I." Major revisions to the Code Case will, however, result in a revision to this guide (1.72). Filament-wound struc-tures have mechanical properties superior to fiberglass-filled laminates, and they are con-sidered more desirable when intended for.safety-related pressure components.


The Code Case obtains an allowable design stress from the hydrostatic design basis (HDB)strength as derived from either Procedure A 1 Copies may be obtained from the American Society of Mechan-ical Engineers, United Engineering Center, 345 East 47th Street, New York, New York 1001
Wash n. D.C. 0 .Aato Okectr. DivIon of Techicsl Iformation and Document Contol.


===7. USNRC REGULATORY ===
(cyclic) or Procedure B (static) of Specifica tion ASTM D-2992, "Standard Method for Ob taining Hydrostatic Design Basis for Reinforced Thermosetting Resin Pipe and Fittings Proce dures." 2 These procedures are intended to be used for general applications for Class 3 piping. For safety-related systems such as spray pond piping, a design factor of 6 is desired. Under some conditions, the qualifica tion procedures may not result in. a design factor of 6, and it is therefore necessary to perform an additional short-time cyclic and burst test to ensure that the desired design factor is obtained.
GUIDES Comments should be sent to the Secretary of the Commission, U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, Attention:
Docketing and Regulatory Guides are issued to describe and make available to the public Service Branch.methods acceptable to the NRC staff of implementing specific parts of the Commission's regulations, to delineate techniques used by the staff in evalu- The guides are issued in the following ten broad divisions:
sting specific problems or postulated accidents, or to provide guidance to applicants.


Regulatory Guides are not substitutes for regulations, and com- 1. Power Reactors 6. Products pliance with them is not required.
Failure is defined in ASTM D-2992 as either leaking, weeping, or bursting.


Methods and solutions different from those 2. Research and Test Reactors 7. Transportation set out in the guides will be acceptable if they provide a basis for the findings 3. Fuels and Materials Facilities
Whichever of these occurs first defines failure.
8. Occupational Health requisite to the issuance or continuance of a permit or license by the 4. Environmental and Siting 9. Antitrust and Financial Review Commission.


5. Materials and Plant Protection
General guidance for loading combinations relative to design limits for Class 3 piping may be found in Regulatory Guide 1.48, "Design Limits and Loading Combinations for Seismic Category I Fluid System Components." How ever, specific equations and limits from Code Case N-155 are not addressed in Regulatory Guide 1.48.  Normal commercial practice provides a weather-resistant coating to the exterior of RTR piping that will be exposed to weather conditions.
10. General Requests for single copies of issued guides (which may be reproduced)
or for Comments and suggestions for improvements in these guides are encouraged at placement on an automatic distribution list for single copies of future guides all times, and guides will be revised, as appropriate, to accommodate comments in specific divisions should be made in writing to the U.S. Nuclear Regulatory and to reflect new information or experience.


This guide was revised as a result Commission, Washington, D.C. 205&5, Attention:
Experience has shown that this practice provides adequate protection for the service considered in this guide. Distribution of resin is generally such that more resin Is applied to the exterior of the pipe than to the interior, and part of the outer resin may have special properties to protect the underlying material from deleterious effects from sources such as ultraviolet radiation and weather. RTR piping has been used to distribute cooling water to nozzles in spray ponds. It Is desirable to provide weather protection to such piping.  However, the omission of an exterior protective coating would be acceptable for piping installed in covered but accessible trenches, provided the inservice inspection frequency is increased to require visual inspection for leaks of all such piping at least once every year. Limited information is available on the effects of radiation on laminates (fiberglass and resin materials bonded together).  
Director, Division of of substantive comments received from the public and additional staff review. Technical Information and Document Control.
However, short time exposure tests have been made, and they showed no appreciable change in the tensile strength of the pipe test piece. For cooling water application,.
there appears little opportu nity for radiation exposure, and the piping should be acceptable without additional testing.


point B), constitut,;
This guide does not address the acceptability of RTR piping for other systems. If RTR piping is considered for systems such as liquid radwaste systems where it may be exposed to long-term radiation, the laminates should be a Copies may be obtained from the Amerien Society for Testing and Materal$, 1915 Racm Street, Philadelphia, Pennsylvania
the acceleration region of the horizontal Design Response Spec-tra.
19103.tested and qualified" for the intended environ ment. Use of RTR piping for systems other than spray ponds would be considered on a case-by-case basis only.  Metal pressure vessels and closed systems "are provided with pressure relief valves or devices for protection against overpressure.


For frcquencies higher than 33 cps. the maximum ground acceleration line thc Design RCeptm.c Spcctra.lie vertical cuomponent Design Response Spectra corresponding to the maximum horizontal ground auceicru/ahm of 1.0 g are shown in Figure 2 of this guide.The numerical values of design displacements, velocities, and accelerations in these spectra arc obtained by iultiplying the corresponding values of the maximum horrn tai ground motion (acceleration
Where RTR piping systems are used for open ended systems such as the cooling water distri bution for spray ponds, the relief valve provi sions may be omitted. However, it is desirable to protect the integrity of the piping by other means such as selection of spray nozzles to prevent their clogging or selection of pump delivery characteristics to prevent the piping pressure from exceeding the design pressure for the piping. Industry experience with fiberglass reinforced resin pressure vestels-and piping extends over 20 to 23 years of service I experience during which the performance of fiberglass-reinforced resin piping has been satisfactory.
= 1.0 g and displacement
= 36 in.) by the factors given in Table II of this guide. The displacement region lines of the Design Response Spectra are parallel to the maximum ground displacement line and are shown on the left of Figure 2.The velocity region lines slope downward from a frequency of 0.25 cps (control point D) to a frequency of 3.5 cps (control point C) and are shown at the top.The remaining two sets of lines between the frequencies of 3.5 cps and 33 cps (control point A), with a break at I %e frcquency of 9 cps (control point B), constitute the acceleration region of the vertical Design Response Spectra. it should be noted that the vertical Design Response Spectra values are 2/3 those of the horizontal Design Response Spectra for frequencies less than 0.25;tor frequencies higher than 3.5, they are the same, while the ratio varies between 2/3 and I for frequencies between 0.2S and 3.5. For frequencies higher than 33 cps. the Design Respone Spectra follow the maximum ground acceleration line.The horizontal and vertical component Design Response Spectra in Figures 1 and 2, respectively, of this guide correspond to a maximum horizontal ground acceleration of 1.0 g. For sites with different acceleration values specified for the design earthquake, the Design Response Spectra should be linearly scaled from Figures I and 2 in proportion to the specified maximum horizontal ground acceleration.


For sites that (1) are relatively close to the epicenter of an expected earthquake or (2) have physical characteristics that could significantly affect the spectral pattern of input motion, such as being underlain by poor soil deporits.the procedure described above will not apply. In these cases, the Design Response Spectra should he developed indivdually according to the site characteristics.
Industry claims that the life expectancy for properly installed piping is at least 40 years, the' normal design life for presently planned- nuclear- power plants. Since RTR piping applications will be limited to temperatures less than 65 0 C (149 0 F). except for occasional transients to 1000C (212 0 F), there is little need for applying insulation to such piping. Hence it should be left bare to make the piping readily, accessible for inspec tion. Since the NRC' staff is allowing only 105 cycles for qualification testing of the piping, special precautions should be taken to ensure that the design assumptions are not exceeded.


C. REGULATORY
The preoperational testing program should include tests of the installed piping to ensure absence of vibration due to weather conditions or water flow that may fatigue the piping beyond values assumed in the design of the system. Inservice inspection requirements should be similar to those in ASME Code, Section XII for Class 3 components.
POSITION 1. The horizontal component ground Design Response Spectra, without soil-structure interaction effects, of the SSE, 1/2 the SSE, or the OBE on sites underlain by rock or by soil should be linearly scaled from Figure 12 in proportion to the maximum horizontal ground acceleration specified for the earthquake chosen. (Figure 1 corresponds to a maximum horizontal ground acceleration of 1.0 g and accompanying displacement of 36 in.) The applicable multiplication factors and control points are given in Table 1. For damping ratios not included in Figure I or Table I, a linear interpolation should be used.2. The vertical component ground Design Response Spectra, without soil-structure interaction effects, of the SSE, 1/2 the SSE, or the OBE on sites underlain by rock or by soil should be linearly scaled from Figure 2 in proportion to the maximum horizontal ground acceleration specified for the earthquake chosen. (Figure 2 is based on a maximum honzmtal round accekration of 1.0 g and accompanying displacement of 36 in.) The applicable multiplication factors and control points an given in Table 11. For damping ratios not included in Figure 2 or Table II, a linear interpolation should be used.2 This does not apply to sites which (I) are reattwely clom to the epicenter of an expected earthquake or (2) which hav physical characteristies that could apuficntly affect the spectra tmbmiatton of input motion. The D=srp Respons Spectra for such sites sould be dveioped on a bets.1.60-2 DEFINITIONS
 
Response Spectrum mcans a plot (4 Ihc maximuin response (acceleration, velocity.
3 The inspection for Code Class 3 components involves a visual inspection of the piping for evidence of unanticipated leakage and structural distress.


or displaceennt)
Since the support of RTR piping may be sensitive, each inservice inspection of such piping should include all its supports.
of a family of idealized single-degice-of-frcedin, damped oscillators as a function of natural frequencies (or periods) of the oscillators to a specified vibratory motion input at their supports.


When obtained from a recorded earthquake record, the response spectrum tends to be irregular, with a number of peaks and valleys.Delip Respim Spectrum is a relatively smooth relatlionship obtained by analyzing, evaluating, and statistically combining a number of individual response spectra derived from the records of significant past earthquakes.
C. REGULATORY
POSITION Safety-related spray pond piping components made from fiberglass-reinforced thermosetting
3 Components classified as NRC Quality Group At B,. ard C should conform to the requirements of the ARMi Boiler and Pressure Vessel Code for Class 3 components (NBC Regulatory Guide 1.25, Group Classificatio and Standards for Water-, Steam-, and Radoactive-Wuts-Containing Components ot Nuclear Power Plants-).1.72-2 resin should comply with ASME Code Case N-155-l (1792-1) supplemented by the follow ing: 1. The design temperature for spray pond piping should be 100 0 C (212 0 F).  2. The allowable design stress should be the value obtained from the minimum HDB (hydro static design basis) in Table 3611-1 of Code Case N-155-1 (Procedure A or B) or the value determined as one-sixth of the stress obtained from a short-time burst test for the pipe being qualified, whichever is lower. The short-time burst strength should be determined by bursting the pipe (ASTM D-1599-74 using free end mounting)
after it has been exposed to 105 pressure cycles from atmospheric to design pressure.


Maximum (peak) Ground Azcceierltion specified for a gwen site means that value of the acceleration which corresponds to zero period in the design response spectra for that site. At zero period the design response spectra acceleration is identical for all damping values and is equal to the maximum (peak) ground acceleration specified for that sit
3. The value of "K" in equation 9 of para graph 3652.2 should be limited to 1.2 unless it can be demonstrated that with the use of a large value of K the functional capability of the system will not be impaired during upset and emergency conditions.


====e. TABLE I HORIZONTAL ====
4. The following items should be identified:
DESIGN RESPONSE SPECTRA RELATIVE VALUES OF SPECTRUM AMPLIFICATION
a. The physical location of the system in relation to other safety-related systems, b. The design and service loads, and c. The value of "B" to be used in equa tion 1 of paragraph
FACTORS FOR CONTROL POINTS Pero t Amplifitimtlon Factors for Control Points of. ..CrOtf imiraion Oispliammanth
3641.1, together with justification for its selection.
2 iticei Dmping A(33 cps) 8(9 qos) C(2.5 qu I0(0.26 qCR 0.5 1.0 4.96 5.95 3.20 2.0 1.0 3.54 4.25 2.50 5.0 1.0 2.61 3.13 2.05 7.0 1.0 2.27 2.72 1.88 10.0 1.0 1.90 2.28 1.70'Maximum ground displacement is taken proportkma to maximn gpound acoilwation, and is 36 in. for pound accel ation of 1.0 gravity.'A6meimtion and displacement amplificition factors ame taken ftom reconumaenitions given in reference
1.1.60-3 VERTICAL DESIGN RESPONSE SPECTRA RELATIVE VALUES OF SPECTRUM AMPLIFICATION
FACTORS FOR CONTROL POINTS Percnt Amplification Factors. for Control Points of Critical Acceleration'
2 Displacements I oemping A(33 cps) B(9 cps) C(3.5 cps) D10.25 CpS)0.5 1.0 4.96 5.67' 2.13 2.0 1.0 3.54 4.05 1.67 5.0 1.0 2.61 2.98 1.37 7.0 1.0 2.27 2.59 1.25 I0.0 1.0 1.90 2.17 1.13'Maximum ground dispiaoCCncnt is taken proportional to maximum ground acceleration and is 36 in. for ground accelcratin of 1.0 gravity.' Accelcration anipl-aticaton factors for the verti'al design v.sXmnne spectra arc equal to those for uorizontal design rcsponse spectra at a given frequency.


whereas displacement amplification factors are 2/3 those for hori-r ,lial design response spectra. Thesc ratios between the amplification factors for the two desin response spcctra are in aprcement with those recommcnded in reference
5. Pressure-relief devices may be omitted for piping systems that are open-ended and for which the system pressure is limited by other means (such as nonclogging spray nozzles and self-limiting pump characteristics)
1.'Thewe values were changed to make this table consistent with the dis.Luimmin of vertical components in Section 8 of this guid
to design pressure.6. RTR piping should be uninsulated or uncovered and installed under conditions that make it readily accessible for inspection.


====e. REFERENCES====
7. Preoperational and inservice inspections should be as follows: a. During the preoperational testing peri od, tests should be made to verify that the piping is free of vibration induced by weather conditions or water flow that could fatigue the piping prematurely.
I. Newmark, N. M., John A. Blume, and Kanwar K.Kapur, "Design Response Spectra for Nuclear Power PIlnts," ASCE Structural Engineering Meeting, San Francisco.


April 1973.2. N. M. Newmark Consulting Engineering Services, "A Study of Vertical and Horizontal Earthquake Spectra," Urbana, Illinois, USAEC Contract No.AT(49-5)-2667.
b. Fiberglass-reinforced piping components should be inspected in accordance with ASME Code, Section XI, for Code Class 3 compo nents .3 In addition, all pipe supports should be inspected.


WASH-1255, April 1973.3. John A. Blume & Associates, "Recommendations for Shape of Earthquake Response Spectra," San Francisco, California, USAEC Contract No.AT(49-5)-301
c. Inspection frequency for piping should be increased to once annually if an exterior weather-resistant coating is not provided.
1, WASH-1254, February 1973.1.60-4 I--0.1 0.2 0.5 1 2 5 10 20 50 100 FRF IUENCY, qu FIGURE


===1. HORIZONTAL ===
==D. IMPLEMENTATION==
DESIGN RESPONSE SPECTRA -SCALED TO lg HORIZONTAL
The purpose of this section is to provide information to license applicants and licensees regarding the NRC staff's plans for using this regulatory guide. This guide reflects current NRC staff prac tice. Therefore, except in those cases in which the applicant proposes an acceptable alter native method for complying with ,specified por tions of the Commission's regulations, the method described herein is being and will con tinue to be used in the evaluation of submittals in connection with operating license or con struction permit applications until this guide is revised as a result of suggestions from the public or additional staff review.1.72-3}}
GROUND ACCELERATION
low0 q~4b 10 KK 0.1 0.2 0. 1 2 5 10 20 50 100 FREQUENCY, q FIGURE 2. VERTICAL DESIGN RESPONSE SPECTRA -SCALED TO 1g HORIZONTAL
GROUND ACCELERATION
UNITED STATES NUCLEAR REGULATORY
COMMISSION
WASHINGTON, D.C. 20555 FIRST CLASS MAIL POS1 AGE & FEES PAID USN RC WASH D C PE RMIT No .Jil OFFICIAL BUSINESS PENALTY FOR PRIVATE USE. $300}}


{{RG-Nav}}
{{RG-Nav}}

Revision as of 09:35, 14 July 2019

Spray Pond Piping Made from Fiberglass-Reinforced Thermosetting Resin
ML003740253
Person / Time
Issue date: 11/30/1978
From:
Office of Nuclear Regulatory Research
To:
References
RG-1.72, Rev 2
Download: ML003740253 (3)
v • d • e


U.S. NUCLEAR REGULATORY

COMMISSION

Revision 2 November 1978 REGULATORY

GUIDE OFFICE OF 'STANDARDS

DEVELOPMENT

REGULATORY

GUIDE 1.72 SPRAY POND PIPING MADE FROM FIBERGLASS-REINFORCED

THERMOSETTING

RESIN

A. INTRODUCTION

General Design Criterion 1, "Quality Stand ards and Records," of Appendix A, "General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50, "Domestic Licensing of Pro"-duction and Utilization Facilities," requires that structures, systems, ý and .components important

..to safety be designed, fabricated, erected, and tested to quality standards com mensurate with the importance of the safety functions to be performed.

Appendix B, "Qual ity Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants," to 10 CFR Part 50 requires that measures be established to ensure materials control and control of special processes such as resin molding.

Section 50.55a, "Codes and Standards," of 10 CFR Part 50 requires that design, fabrica tion, installation, testing, or inspection of the specified system or component be in accordance with generally recognized codes and staridards.

Footnote 6 to § 50.55a states that the use of specific Code Cases may be authorized by the Commission upon request pursuant to § 50.55a (a)(2)(ii), which requires that proposed alter natives to the described requirements or por tions thereof provide an acceptable, level of quality and safety. This guide describes a method acceptable to the NRC staff for implementing these require ments with regard to the design, fabrication, and testing of fiberglass-reinforced thermo setting resin (RTR) piping for spray pond applications.

This guide applies to light-water cooled and gas-cooled reactors. .The Advisory Committee on Reactor Safeguards has been con sulted concerning this guide and has concurred in the regulatory position.

  • Lines indicate substantive changes tram previous issu

e. USNRC REGULATORY

GUIDES Regulatory Guides eam issued So descilbe end make svalable ID ft publi methods acCeptable w to NRC staff al ill*em ntig apeodf pIne o .on Com 'laln rguatl Io denwte lecdn-,= wed by 1w staff in evsu~ pcfcproblems or postiletad aceldents.

Or ID prVOvd gJUWdnc 10 nt.Ragulatory Gulde. wre hiot subeftfts te 10"0 sauelosnd corn pence with irn Is not equkL Meihods and eolutlona dffrent rom *so s out in weidss v be = "*e thP prfdo r a *Xe&W Me e c.n aetr ka by to Corm desio Comnenwts n uggestou wo fo tr aov~ament meh 1wae idesare ncourasgdat of I m. n wgukd. .Ube ,ebed. as Pfrpiat. 10 sci10date camnme and 10 ~sic now infomato or expe-rienoe.

This guide was orvised ae remit of subetantie coment isev OM 111 pubic end additional emil revlew.

B. DISCUSSION

The ASME Boiler and Pressure Vessel Com mittee publishes a document entitled "Code Cases." Generally, a Code Case explains the 'intent of rules in the ASME's Boiler and Pressure Vessel Code (the Code)' or provides for alternative requirements under special circumstances.

Most Code Cases are evehtually Ssuperseded by Lrevisions to the Code and then are annulled by action of the ASME Council.

Code Case N-155-1 (1792-1), referred to in this guide, is limited to Section III, Division 1, of the Code and is oriented toward design and fabrication of RTR piping. The Code Case does not prescribe a lower temperature limit, prima rily because the American Society for Testing and Materials (ASTM) specifications do not contain a lower temperature" limit, but RTR piping systems would normally be qualified for the intended service temperature condition.

It is planned that after Revision 2 of, this guide is issued, the acceptability of future minor revisions to Code Case N-155 (1792) will be noted in Regulatory Guide 1.84, "Design and Fabrication Code Case Acceptability--ASME

Section III Division I1." Major revisions to the Code Case will, however, result in a revision -to this guide -(1.72). Filament-wound struc tures have mechanical properties superior to fiberglass-filled laminates, and they are con sidered more desirable when intended for safety-related pressure components.

The Code Case obtains an allowable design stress from the hydrostatic design basis (HDB) strength as derived from either Procedure A Copies Jay be obtained from the American Society of Mechan ticl Inghieers.

United Ingieerling Canter, 345 Seat 47th Street. New Terk. New Yorkt 10017.Connffao awloid be se nt fto Ssem" of Me CommisIonS

U.S. Nucea noguitor Commission Washingon D.C. *W Attntion:

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(cyclic) or Procedure B (static) of Specifica tion ASTM D-2992, "Standard Method for Ob taining Hydrostatic Design Basis for Reinforced Thermosetting Resin Pipe and Fittings Proce dures." 2 These procedures are intended to be used for general applications for Class 3 piping. For safety-related systems such as spray pond piping, a design factor of 6 is desired. Under some conditions, the qualifica tion procedures may not result in. a design factor of 6, and it is therefore necessary to perform an additional short-time cyclic and burst test to ensure that the desired design factor is obtained.

Failure is defined in ASTM D-2992 as either leaking, weeping, or bursting.

Whichever of these occurs first defines failure.

General guidance for loading combinations relative to design limits for Class 3 piping may be found in Regulatory Guide 1.48, "Design Limits and Loading Combinations for Seismic Category I Fluid System Components." How ever, specific equations and limits from Code Case N-155 are not addressed in Regulatory Guide 1.48. Normal commercial practice provides a weather-resistant coating to the exterior of RTR piping that will be exposed to weather conditions.

Experience has shown that this practice provides adequate protection for the service considered in this guide. Distribution of resin is generally such that more resin Is applied to the exterior of the pipe than to the interior, and part of the outer resin may have special properties to protect the underlying material from deleterious effects from sources such as ultraviolet radiation and weather. RTR piping has been used to distribute cooling water to nozzles in spray ponds. It Is desirable to provide weather protection to such piping. However, the omission of an exterior protective coating would be acceptable for piping installed in covered but accessible trenches, provided the inservice inspection frequency is increased to require visual inspection for leaks of all such piping at least once every year. Limited information is available on the effects of radiation on laminates (fiberglass and resin materials bonded together).

However, short time exposure tests have been made, and they showed no appreciable change in the tensile strength of the pipe test piece. For cooling water application,.

there appears little opportu nity for radiation exposure, and the piping should be acceptable without additional testing.

This guide does not address the acceptability of RTR piping for other systems. If RTR piping is considered for systems such as liquid radwaste systems where it may be exposed to long-term radiation, the laminates should be a Copies may be obtained from the Amerien Society for Testing and Materal$, 1915 Racm Street, Philadelphia, Pennsylvania

19103.tested and qualified" for the intended environ ment. Use of RTR piping for systems other than spray ponds would be considered on a case-by-case basis only. Metal pressure vessels and closed systems "are provided with pressure relief valves or devices for protection against overpressure.

Where RTR piping systems are used for open ended systems such as the cooling water distri bution for spray ponds, the relief valve provi sions may be omitted. However, it is desirable to protect the integrity of the piping by other means such as selection of spray nozzles to prevent their clogging or selection of pump delivery characteristics to prevent the piping pressure from exceeding the design pressure for the piping. Industry experience with fiberglass reinforced resin pressure vestels-and piping extends over 20 to 23 years of service I experience during which the performance of fiberglass-reinforced resin piping has been satisfactory.

Industry claims that the life expectancy for properly installed piping is at least 40 years, the' normal design life for presently planned- nuclear- power plants. Since RTR piping applications will be limited to temperatures less than 65 0 C (149 0 F). except for occasional transients to 1000C (212 0 F), there is little need for applying insulation to such piping. Hence it should be left bare to make the piping readily, accessible for inspec tion. Since the NRC' staff is allowing only 105 cycles for qualification testing of the piping, special precautions should be taken to ensure that the design assumptions are not exceeded.

The preoperational testing program should include tests of the installed piping to ensure absence of vibration due to weather conditions or water flow that may fatigue the piping beyond values assumed in the design of the system. Inservice inspection requirements should be similar to those in ASME Code,Section XII for Class 3 components.

3 The inspection for Code Class 3 components involves a visual inspection of the piping for evidence of unanticipated leakage and structural distress.

Since the support of RTR piping may be sensitive, each inservice inspection of such piping should include all its supports.

C. REGULATORY

POSITION Safety-related spray pond piping components made from fiberglass-reinforced thermosetting

3 Components classified as NRC Quality Group At B,. ard C should conform to the requirements of the ARMi Boiler and Pressure Vessel Code for Class 3 components (NBC Regulatory Guide 1.25, Group Classificatio and Standards for Water-, Steam-, and Radoactive-Wuts-Containing Components ot Nuclear Power Plants-).1.72-2 resin should comply with ASME Code Case N-155-l (1792-1) supplemented by the follow ing: 1. The design temperature for spray pond piping should be 100 0 C (212 0 F). 2. The allowable design stress should be the value obtained from the minimum HDB (hydro static design basis) in Table 3611-1 of Code Case N-155-1 (Procedure A or B) or the value determined as one-sixth of the stress obtained from a short-time burst test for the pipe being qualified, whichever is lower. The short-time burst strength should be determined by bursting the pipe (ASTM D-1599-74 using free end mounting)

after it has been exposed to 105 pressure cycles from atmospheric to design pressure.

3. The value of "K" in equation 9 of para graph 3652.2 should be limited to 1.2 unless it can be demonstrated that with the use of a large value of K the functional capability of the system will not be impaired during upset and emergency conditions.

4. The following items should be identified:

a. The physical location of the system in relation to other safety-related systems, b. The design and service loads, and c. The value of "B" to be used in equa tion 1 of paragraph

3641.1, together with justification for its selection.

5. Pressure-relief devices may be omitted for piping systems that are open-ended and for which the system pressure is limited by other means (such as nonclogging spray nozzles and self-limiting pump characteristics)

to design pressure.6. RTR piping should be uninsulated or uncovered and installed under conditions that make it readily accessible for inspection.

7. Preoperational and inservice inspections should be as follows: a. During the preoperational testing peri od, tests should be made to verify that the piping is free of vibration induced by weather conditions or water flow that could fatigue the piping prematurely.

b. Fiberglass-reinforced piping components should be inspected in accordance with ASME Code,Section XI, for Code Class 3 compo nents .3 In addition, all pipe supports should be inspected.

c. Inspection frequency for piping should be increased to once annually if an exterior weather-resistant coating is not provided.

D. IMPLEMENTATION

The purpose of this section is to provide information to license applicants and licensees regarding the NRC staff's plans for using this regulatory guide. This guide reflects current NRC staff prac tice. Therefore, except in those cases in which the applicant proposes an acceptable alter native method for complying with ,specified por tions of the Commission's regulations, the method described herein is being and will con tinue to be used in the evaluation of submittals in connection with operating license or con struction permit applications until this guide is revised as a result of suggestions from the public or additional staff review.1.72-3


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