ML19289E108
| ML19289E108 | |
| Person / Time | |
|---|---|
| Issue date: | 02/28/1979 |
| From: | NRC OFFICE OF STANDARDS DEVELOPMENT |
| To: | |
| Shared Package | |
| ML19289E105 | List: |
| References | |
| RTR-REGGD-1.148, TASK-OS, TASK-SC-704-5 REGGD-01.XXX, REGGD-1.XXX, NUDOCS 7904020222 | |
| Download: ML19289E108 (16) | |
Text
[p ntc [s U.S. NUCLEAR REGULATORY COMMISSION February 1979 t
0FFICE OF STANDARDS DEVELOPMENT Division 1
, [
DRAFT REGULATORY GUIDE AND VALUE/ IMPACT STATEMENT Task SC 704-5 o
.e -
FUNCTIONAL SPECIFICATION FOR SAFETY-RELATED VALVE ASSEMBLIES IN NUCLEAR POWER PLANTS A.
INTRODUCTION Section III, " Design Control," of Appendix B, " Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants," to 10 CFR Part 50, " Domestic Licensing of Production and Utilization Facil-ities," requires, in part, that measures be established to ensure that regulatory requirements and the design basis for applicable structures, systems, and comoonents are correctly translated into specifications, drawings, procedures, and instructions.
This guide delineates a proce-dure acceptable to the NRC staff for implementing the Commission's regu-lations with respect to detailed specification of information pertinent to definition of operating requirements for valve assemblies whose safety-related function is to open, close, or regulate fluid flow in light-water-cooled nuclear power plants.
This guide will be appliect to active valve 1
assemblies in all light-water-cooled nuclear power plants.
1As identified in accordance with Section 3.9.3.2 of Regulatory Guide 1.70, Revision 3, "Standt rd Format and Content of Safety Analysis Reports for Nuclear Power Plants."
790402023 This, regulatory guide and the associated value/ impact statement are being issued in draft fann to involve the public in the early stages of the development of a regulatory position in this area. They have not received complete staff review and do not represent an official NRC staff position.
Public con.ent are being sr.llcited on both drafts, the guide (including any implementation schedule) and the value/ impact statement. Cements on the value/frpact statement shculd be accompanied by supporting da ta. Ccments on both drafts should be sent to the Secretary of the Comission, U.S.. Nuclear Regulatory Comission, Washington, D.C. 20555, Attention: Docketing and Service Oranch, by 7
Requests for single copies of issued guides and draft guides (wnich eay be reproduced) or for placement on an autetaatic distr'bution list for single copies of future guides and draft guidas in specif!c divisions should be fnade in writing to the U.S. Nuclear Regulatory Conr:issien, Washington, D.C. 20555, Attention:
Director, Division of Technical Infon"ation and Docurent Centrol.
G B.
DISCUSSION The rules for construction of nuclear components given in Section III of the ASME Boiler and Pressure Vessel Code (the Code) do not, as indicated in NCA-2142(b) of the 1977 Edition,2 ensure operability of components in which mechanical motion is required.
Since valve assembly operability is necessary to ensure performance of some safety-related systems in nuclear power plants, the American National Standards Institute (ANSI) established a group to provide direction for development of the necessary standards that would provide assurance of valve assembly operability.
The first standard to be published as a result of that effort is ANSI N278.1-1975, "Self-Operated and Power-Operated Safety-Related Valves Functional Specification Standard."4 This standard requires tnat a Functional Specification be prepared that (1) identifies the safety-related function of the valve assembly and (2) delineates the set of conditions important to valve assembly operability.
ANSI N278.1-1975 establishes a consistent approach to specifying the minimum inforrr.ation needed to identify th,e requirerents for function and operability of safety-related valve assemblies.
Although the standard 2Copies of the ASME Boiler and Pressure Vessel Code,Section III, 1977 Edition, may be obtained from the American Society of Mechanical Engineers, United Engineering Center, MS East 47th Street, New York, N.Y. 10017.
A valve assembly is comprised of the pressure retaining parts of the valve body, internals, actuator, and functional accessories.
4Copies may be obtained from the American Society of Mechanical Engineers, United Engineering Center, 345 East 47th Street, New York, N.Y. 10017.
O 2
D has not been extensively used because of its relatively recent publi-cation, it is apparent that it would be useful for any safety-related Quality Group A, B, C, or D valve assembly.
However, there are questions relative to whether this detailed functional specification is necessary for all (or for certain specified) safety-related valve assemblies.
It is anticipated that the breadth of application of this standard might develop gradually as a function of user experience, quality group classi-fication of a particular valve assembly, and valve assembly function within a given plant system and also whether the functional specification applies to an individual valve assembly or a group of valve assemblies.
In this context, specifications would most likely evolve from systems analyses and, as such, could be compatible with applicable system safety criteria through appropriate use of limit range, maxima, minima, envelope of important parameters, or generally accepted approaches consistent with industry practice.
It is evident that a thorough process to identify specific valve assemblies that should have functional specifications in accordance with this standard would be extremely difficult because of differing plant system characteristics.
One desirable goal for initial application of the standard would be to provide a relatively wide spectrum of use cover-ing several Quality Group classifications in order to develop adequate experience to determine a breadth of application for the standard.
The NRC staff believes that " active" valve assemblirt identified in Sec-tion 3.9.3.2 of Regulatory Guide 1.70, Revision 3, " Standard Format and 3
s e
Content of Safety Analysis Reports for Nuclear Power Plants," are repre-sentative of such a spectrum as well as being very important to plant safety.
Therefore, the staff proposes that initial application of this standard should at least encompass " active" valve assemblies.
For use with this regulatory guide, the staff intends that " active" valve assemblies should be identified according to the guidance provided in Subsection II.2, ' Pump and Valve Operability Assurance Program," of Section 0.9.3 of the Standard Review Plan.
A proposed revision to the Standard Review Plan will also affect previous definitions of " active."
The proposed definition that the staff plans to use is as follows:
" Active Pumps and Valves - A pump or valve that must perform a mechan-ical motion in order to shut down the plant or mitigate the consequence of a postulated event.
Safety and relief valves are specifically included."
It appears that component standards usually concentrate on accom-plishing a single goal such as providing pressure bound:;ry integrity even though it may be necessary to address a relatively broad subject matter which could include materials properties, design rules, testing rules, and certification requirements in order tc meet the desired goal.
An example of this approach isSection III, " Nuclear Power Plant Components,"
of the ASME Boiler and Pressure Vessel Code.
Similarly,Section XI,
" Rules for Inservice Inspection of Nuclear Power Plant Components," of the ASME Code provides, as one of several goals, rules for inservice testing of valve assemblies while ANSI Standard N278.1-1975 is directed O
4
D at operability of safety-related valve assemblies.
It is therefore evi-dent that the complete spectrum from construction through operability to inservice testing of a valve assembly is covered,,by separate codes and standards even though there is a necessary relationship among them.
Hence, the staff believes that (1) there is a need for a set of compre-hensive requirements to provide the detailed documentation that serves as the basis for construction, assurance of operability, ;nservice testing, and applicability of and relationship among the separate standards and (2) there should be both technical compatibility and consistent require-ments for similar issues among the documents that comprise the set of comprenensive requirements.
Accordingly, those valve assemN ies that are class,fsed as ASME Code Class 1, 2, or 3 (Quality Groups A, B, and C, respectively, as identified in Regulatory Guide 1.26, " Quality Group Classifications and Standards for Water, Steam, and Radioactive-Waste-Containing Components of Nuclear Power Plants") are relatively amenable to meeting a set of comprehensive requirements.
One approach to aid in providing this set of requirements would be to include the Functional Specification requirements of ANSI N278.1-1975 with the Design Specification requirements of NCA-3250 in Section III of the ASME Code.
Also, it appears advisable, at least for Class 1, 2, and 3 valve assemblies, that the Functional Specification bAs defined in Section III of the ASME Code, " construction" is an all-inclusive term comprising materials, design, fabrication, examina-tion, testing, inspection, and certification required in the manufacture and installation of items.
5
0 recognize and reference certain relationships pertaining to the use or applicability of Section XI, " Rules for Inservice Inspection of Nuclear Power Plant Components," and Code Case 1621-2, " Internal and External Valve Items." Although valves classified as Quality Group D (those that use the ANSI B31.1.0 standard) in Regulatory Guide 1.26 may not have the desired specific relationship between the Functional Specification and the document that serves as the basis for construction (the Desian Speci-fication of ASME Code Class 1, 2, and 3 valves), there is still a need for a set of comprehensive requirements.
C.
REGULATORY POSITION The requirements aelineated in ANSI N278.1-1975, "Self-Operated and Power-0perated Safety-Related Valves Functional Sp;cification Standard,"
(1) are generally acceptable to the NRC staff for fur.ctional specifica-tions of " active" valve assemblies whose operability must be ensured and (2) provide an adequate basis for complying with those requirements of Section III, " Design Control," of Appendix B to 10 CFR Part 50 relating to the correct translation into specifications, as supplemented or medi-fied by the following:
1.
Applicability and Relationship With Other Standards a.
The scope of ANSI N278.1-1975, as stated in Section 1 of the standard, should be supplemented to include safety-related manually operated valve assemblies.
O 6
i b.
The phrase design specification relationship, used in Section 2 of the standard to indicate an interrelationship with other codes and
(,[
gr j
standards, should be broadly interpreted to include a document that contains sufficient detail to serve as a " complete basis for construction" and may, as appropriate, be called an equipment specification, procurement specification or some similar term that includes the Design Specifica-A q
tion required by the ASME Code.
However, when valve operability is a
?.
requirement, the Functional Specification required by N278.1-1975 should I
be provided either as part of, or concurrent with, *,he controlling docu-ment that serves as the " complete basis for construction." For ASME Code Class 1, 2, and 3 valves, the " Valve Design Specification" identified in j
Section 2, of N278.1-197E should be that required by NCA-3250, " Provision of Design Specifications," of Subsection NCA, " General Requirements," of j
Section III, " Nuclear Power Plant Components" of the ASME Code.
i i
The valve Functional Specification should meet the following c.
requirements in the ASME Code:
(1)
It should be uniquely identified and referenced in the Design Specification in accordance with NCA-3252(a)(6),6 I
(2)
It should reference the applicable Design Specification to
~
permit identification of both documents.
6ASME Boiler and Pressure Vessel Code,Section III - Division 1, 1977 Edition, Summer 1977 Addenda.
7
=
G (3)
It should meet those portions of the filing requirements of NCA-3256 which indicate "a copy shall be filed at the location of the installation and made available to the enforcement authorities having jurisdiction over the plant installation."
d.
The Functional Specification prepared in accordance with N278.1-1975 for valve assemblies classified as Quality Group D in Regula-tery Guide 1.26 should be cross referenced with the document that serves as a "r.nplete basis for construction" (see Regulatory Position C.1.b of this guide).
e.
When the Valve Design Specification for ASME Code Class 1, 2, and 3 valve assemb' %s permits use of ASME Code Case 1621-2, " Internal and External Valve Items," the Functional Specification should consider this aspect and usage should be consistent with Regulatory Guide 1.84,
" Code Case Acceptability, ASME Section III Design and Fabrication."
2.
Specific Considerations a.
Section 3.1, " Valve Application Characteristics," should be supplemented by the following:
(1) " Manually-operated valves" (see Regulatory Position C.l.a) as a separate item to the listing.
O 8
I (2) The Functional Specification should identify the relation-ship or correspondence between the " application characteristics" of the subject standard and the Valve Categories A, B, C, D, and E in IWV-2110 of Subsection Ihv, " Inservice Testing of Valves in Nuclear Power Plants,"
of Section XI, " Rules for Inservice Inspection of Nuclear Power Plant Components," of the ASME Code, b.
Section 3.2, " Structural Requirements," should be supplemented by the following:
(1) The time dependence and number of cycles, if applicable, for temperatures, pressures, and dynamic loading resulting from plant transients.
(2) The time relationship between applied seismic iuadings and other concurrent loadings.
(3) The frequency response spectra for the operating basis earthquake and the safe shutdown earthquake as well as other potential forcing frequencies such as from attached piping, pumps, or other equipment.
(4) The maximum differential pressure (considering all plant operating conditions) that exists across the closure device for which valve assembly operation is to be ensured.
9
e c.
Section 3.3, " Operational Requirements," should be supplemented by the following:
(1) The first paragraph should be supplemented by including specification af the valve assembly fail safe response in the event of loss-of-actuator power, e.g.,
fail open, fail closed, fail as is.
(2) In Part e of Section 3.3.1, " Operating Conaitions," the phrase " Normal and Abnormal Plant Operation," should be interpreted to include the events covered by plant " Operational Modes (Condition)", and by the Transient and Accident Classification of Chapter 15, " Accident Analysis," of Regulatory Guide 1.70, " Standard Format and Content of Safety Analysis Reports for Nuclear Power Plants." The Functonal Speci-fication should state whether the specific valve assembly safety function applies to events defined in the plant Operational Modes (Condition) or in the Transient and Accident Classification.
The specification should also indicate whether the actual valve assembly operation (open, close or regulate fluid flow) occurs during or after the specified event.
(3) Part e of 3.3.2 should be supplemented by including motor power and duty requirements, including stall torque.
As defined in the Standard Technical Specifications for Westinghouse, Combustion Engineering, and Babcock and Wilcox Pressurized Water Reactors.
The Standard Technical Specification for reneral Electric Boiling Water Reactors Uses " Condition" rather than " Modes."
O 10
(4)
In lieu of Section 3.3.2.1 " Electrical Power for Valve Actuators and Control Elements," the following should be used:
" Electrical power shall be identified as AC (single phase or three phase), or DC, with voltage and frequency operatng ranges specified."
(5)
In Section 3.3.3, " Environmental Conditions," the terms
" normal" and " abnormal" environmental conditions should be interpreted as the environment that will exist as a result of specified plant conditions.
It should be interpreted that " environmental conditions" include both the environment external to the valve assembly and that of the controlled media internal to the valve assembly.
d.
Section 3.4, " Seat Leakage Limits," should be supplemented, as applicable, by tae following:
(1) The leakage limits identified in paragraph b of this section should include identification of fluid, temperature, and pressure for which the limit applies.
(2)
If valve assenbly function requires a limit on overall leakage (e.g., leakage in addition to that of the main seat such as stem packing and flange), such overall leakage limit should be specified in this section.
11
8 D.
IMPLEMENTATIDN This proposed guide has been released cu encourage public partici-pation in its development.
Except in those cases in which an applicant proposes an acceptable alternative method for complying with specified portions of the Commission's regulations. the method to be described in the active onide reflecting public comments will be used in the evalua-tion of (1) all construction permit applications, (2) standard reference system preliminary design applications (PDA) or Type-2 final design applications (FDA-2), and (3) licenses to manufacture tnat are docketed after the implementation date to be specified in the active guide, except those portions of a construction permit application that:
a.
Reference an approved standard reference system preliminary or final design (PDA or FDA), or an application for approval of such design.
b.
Reference an approved standard duplicate plant preliminary or final design (PDDA or FDDA).
c.
Reference parts of a base plant design qualified and approved for replication.
d.
Reference a plant design approved or under review for approval for manufacture under a Manufacturing License.
This implenentation date (to be specified in the active guide) will in no case be earlier than December 1, 1979.
12
DRAFT VALUE/ IMPACT STATEMENT
Background
Valve assemblies (e.g., pressure retaining portions of the valve, its internals, actuator, and attached functional accessories) installed in nuclear power plants have experienced numerous malfunctions in the past.
According to Licensee Event Reports, these malfunctions occur at a fre-quency that is cause for concern.
The origin of valve assembly malfunc-tions varies widely; however, one of the major problems that was recog-nized at the valve operability meeting held with industry on November 20, 1972, is that equipment -specifications are deficient in defining the application and the environmental and loading conditions for valve assem-blies in nuclear power plants.
As a result of the 1972 meeting, a valve operaoility standards effort was inititated under the auspices of ANSI N45.
Subsequently, this standards development responsibility was trans-ferred to B16 Subcommittee H.
The first of these standards published by ANSI is N278.1, "Self-Operated and Power-Operated Safety-Related Valves Functional Specification Standard." The proposed regulatory Guide endorses that standard with suggested supplemental guidance.
Value AlthCJgh this standard, N278.1-1975, provides requirements important for adequate definition of valve assembly application and operating condi-tions, the standard, by itself, will not provide complete assurance of 13
G valve assembly operability.
It is anticipated that the most important contributions from N278.1-1975 will be realized when subsequent ANSI Standards, which are currently being developed, addressing such topics as valve assembly functional qualification and production testing are in place to provide a set of requirements covering various aspects of valve assembly operability.
However, endorsement of ANSI N278.1 as supplemented by the proposed regulatory position of the guide will provide a uniforn basis and approach for specifying the functional requirements and oper-ability considerations for any particular valve assembly that has a safety-related function.
The proposed guide also introduces the concept of a set of comprehensive requirements covering construction, operability, and intervice testing of safety-related valve assemblies.
In addition, publishing the proposed guide for comment will have the added value of providing impetus to initiate considerations of " breadth of application" aspects poseu by use of this standard as well as subsequent ANSI standards that pertain to valve assembly operability.
Impact The impact of this proposed regulatory guide is expected to be rather limited because licensees are committed to a program to demonstrate valve assembly operability in accordance with Sections 3.9.3.2 and 3.9.6 of Regulatory Guide 1.70, Revision 3, " Standard Format and Content of Safety 9
14
Analysis Reports for Nuclear Power Plants." Additionally, all applicants are cognizant of NRC staff positions on valve assembly operability as identified in Regulatory Guide 1.48, " Design Limits and Loading Combina-tions for Seismic Category I Fluid System Components," and Sections 3.9.3 and 3.9.6 of the Standard Review Plan.
It is therefore evident that the proposed guide does not introduce a new or additional safety subject.
However, the ANSI standard, N278.1-1975, addressed by the proposed guide was published approximately 3 years ago, and there are indications that it has not been extensively used.
It appears that implementation of the proposed guide relative tc which valve assemblies should meat the standard represents the area of greatest potential impact.
Since the staff recom-mends initial application of the standard to " active" valve assemblies, which are addressed in Section 3.9.3.2 of Regulatory Guide 1.70, the impact should be restricted to situations where specific deficiencies exist in individual applicant cquipment specifications.
A thorough process to identify additional safety-related valve assemblies that should have functional specifications in accordance with ANSI N278.1 would require extensive staff time because differing plant system characteristics make it difficult to establish generic groups.
The term
" safety-related" affects this because Regulatory Guide 1.26, " Quality Group Classifications and Standards for Water, Steam, and Radioactive-Waste-Containing Components of Nuclear Power Plants," refers to Quality 15
Groups A, B, C, and D for safety-related components.
However, it may not be desirable or necessary to have all the detail required in the standard for all valve assemblies that may be classified in accordance with Regula-tory Guide 1.26.
Another potential area of ccncern relates primarily to iscensee or its agent relative to purchasing aspects of valve assemblies.
a Application of the specification requirements of this standard to pre-selected valve assemblies could adversely affect current purchasing p ocedures depending on whether purchasing is done individualy or in groups of valve assemblies.
Recommendations It is recommended that the proposad guide should be initially applied to
" active" valve assemblies.
The guide would be acceptable for use with all safety-related valve assemblies, but it should be at the descretion of the licensee because of the potential impact on current procedures.
It is expected that experience acquired through use of the standard with active valve assemblies will provide guidance for wider application in the future.
UNITE D ST ATES NUCLE AR REGULATORY COMMISSION f'
]
W AS HIN GTON. D. C. 20%5 POST AGE AND F E E S P AID OFFICI AL B USI N E SS U.S N U C L E A N H E C. U L A T O H V PE N A L T Y F OR PRIV ATE USE. $300 C OM MISSION L
J 120555003927 1 S t*
US NRC SECY P(J3LIC DOCUMENT R0 0.9 BR A NC H CPIEF HST LaBay WASHINGTCN DC 20555 O