RG 1.192, "Operation and Maintenance Code Case Acceptability, ASME OM Code," Revision 1

	U.S. NUCLEAR REGULATORY COMMISSION	May 2014
		Revision 1
	REGULATORY GUIDE OFFICE OF NUCLEAR REGULATORY RESEARCH

REGULATORY GUIDE 1.192

(Draft was issued at DG-1232, dated June 2013)

OPERATION AND MAINTENANCE CODE CASE ACCEPTABILITY, ASME OM CODE

A. INTRODUCTION

Purpose

This regulatory guide (RG) lists the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) (Ref. 1) Code Cases that the U.S. Nuclear Regulatory Commission (NRC) has approved for use as voluntary alternatives to the mandatory ASME OM Code provisions that are incorporated by reference into Title 10, Part 50, of the Code of Federal Regulations (10 CFR Part 50), “Domestic Licensing of Production and Utilization Facilities” (Ref. 2).

Applicable Rules and Regulations

• General Design Criterion (GDC) 1, “Quality Standards and Records,” of Appendix A, “General Design Criteria for Nuclear Power Plants,” to 10 CFR Part 50 requires, in part, that structures, systems, and components important to safety be designed, fabricated, erected, and tested to quality standards commensurate with the importance of the safety function to be performed. Where generally recognized codes and standards are used, Criterion 1 requires that they be identified and evaluated to determine their applicability, adequacy, and sufficiency and be supplemented or modified as necessary to ensure a quality product in keeping with the required safety function.

• Criterion 30, “Quality of Reactor Coolant Pressure Boundary,” of Appendix A to 10 CFR Part 50 requires, in part, that components that are part of the reactor coolant pressure boundary be designed, fabricated, erected, and tested to the highest practical quality standards.

• Appendix B, “Quality Assurance Criteria for Nuclear Power Plants and Fuel Processing Plants,” to 10 CFR Part requires, in part, a program for inspection of activities affecting quality to verify conformance with documented instructions and procedures.

• The regulation in 10 CFR 50.55a(f), “Inservice Testing Requirements,” requires, in part, that Class 1, 2, and 3 pumps and valves meet the requirements of the ASME OM Code or equivalent quality standards.

Related Guidance

• Regulatory Guide 1.84, “Design, Fabrication, and Materials Code Case Acceptability, ASME Section III, Division 1,” list the ASME Section III Code Cases that the NRC has approved for use as voluntary alternatives to the mandatory ASME BPV Code provisions that are incorporated into 10 CFR 50.55a (Ref. 3).

• Regulatory Guide 1.147, “Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1,” list the ASME Section XI Code Cases that the NRC has approved for use as voluntary alternatives to the mandatory ASME BPV Code provisions that are incorporated into 10 CFR 50.55a (Ref. 4).

• Regulatory Guide 1.193, “ASME Code Cases Not Approved for Use,” is published to provide information regarding the Section III, Section XI, and OM Code Cases that the NRC has determined to be unacceptable for use on a generic basis (Ref. 5).

Purpose of This Regulatory Guide

The NRC will amend 10 CFR 50.55a to incorporate by reference the new Code Cases and revisions to existing Code Cases listed as approved in Tables 1 and 2 of this guide, and to state the requirements governing the use of Code Cases. Code Cases approved by the NRC may be used voluntarily by licensees as an alternative to compliance with ASME Code provisions that have been incorporated by reference into 10 CFR 50.55a. Because of continuing change in the status of Code Cases, the staff plans periodic updates to 10 CFR 50.55a and this guide to accommodate new Code Cases and any revisions of existing Code Cases.

Paperwork Reduction Act

This regulatory guide contains information collection requirements covered by 10 CFR Part 50 that the Office of Management and Budget (OMB) approved under OMB control number 3150-0011.  The NRC may neither conduct nor sponsor, and a person is not required to respond to, a request for information or an information collection requirement unless the requesting document displays a currently valid OMB control number.

B. DISCUSSION

Reason of Revision

This regulatory guide (Revision 2) updates Revision 1 of Regulatory Guide 1.192 by listing the new and revised OM Code Cases reviewed and approved by the NRC and considered for inclusion in Revision 2.

Background

Provisions of the American Society of Mechanical Engineers (ASME) International Boiler and Pressure Vessel (BPV) Code have been used since 1971 as one part of the framework to establish the necessary design, fabrication, construction, testing, and performance requirements for structures, systems, and components important to safety. Among other things, ASME standards committees develop improved methods for the construction, inservice inspection (ISI), and inservice testing (IST) of ASME Class 1, 2, 3, MC (metal containment), and CC (concrete containment) nuclear power plant components. A broad spectrum of stakeholders participate in the ASME process, which helps to ensure that the various interests are considered.

In 1990, the ASME published the initial edition of the “Code for Operation and Maintenance of Nuclear Power Plants (OM Code)” that provides rules for IST and inservice examination of pumps, valves, and dynamic restraints (snubbers). The OM Code was developed and is maintained by the ASME Committee on Operation and Maintenance of Nuclear Power Plants. The OM Code was developed in response to the ASME Board on Nuclear Codes and Standards directive that transferred responsibility for development and maintenance of rules for the IST and inservice examination of pumps, valves, and dynamic restraints (snubbers) from the ASME Section XI Subcommittee on Nuclear Inservice Inspection to the ASME OM Committee. The ASME intended the OM Code to replace Section XI rules for IST and inservice examination of pumps, valves, and dynamic restraints (snubbers), and the Section XI rules for IST and inservice examination of these components that had been incorporated by reference into NRC regulations have been deleted from Section XI. The NRC endorsed the OM Code for the first time in an amendment to 10 CFR 50.55a published on September 22, 1999 (64 FR 51370). The NRC endorsed OM Code Cases through this guide for the first time in June 2003. It should be noted that the title of the OM Code was changed beginning with the 2009 Edition to “Operation and Maintenance of Nuclear Power Plants.”

The ASME periodically publishes a new edition of the OM Code. The latest editions and addenda of the OM Code that have been approved for use by the NRC are referenced in 10 CFR 50.55a(a)(1)(iv). The ASME also periodically publishes OM Code Cases. Code Cases provide alternatives to existing OM Code requirements that the ASME developed and approved. This regulatory guide identifies the OM Code Cases that have been determined by the NRC to be acceptable alternatives to applicable parts of the OM Code. Licensees may use these Code Cases without requesting authorization from the NRC, provided that they are used with any identified limitations or modifications. OM Code Cases not yet endorsed by the NRC may be used by a licensee or applicant through 10 CFR 50.55a(z). That section permits the use of alternatives to the Code requirements referenced in 10 CFR 50.55a provided that the proposed alternatives result in an acceptable level of quality and safety and that their use is authorized by the Director of the Office of Nuclear Reactor Regulation.

The ASME OM Code is incorporated by reference into 10 CFR 50.55a, which the NRC will amend to incorporate this guide by reference; 10 CFR 50.55a states the requirements governing the use of Code Cases. Because of continuing change in the status of Code Cases, the staff plans periodic updates to 10 CFR 50.55a and this guide to accommodate new Code Cases and any revisions of existing Code Cases. Code Cases approved by the NRC provide an acceptable voluntary alternative to the mandatory ASME OM Code provisions.

When a licensee initially implements a Code Case, 10 CFR 50.55a requires that the most recent version of that Code Case as listed in Tables 1 and 2 be implemented. If a Code Case is implemented by a licensee and a later version of the Code Case is incorporated by reference into 10 CFR 50.55a and listed in Tables 1 and 2 during the licensee’s present 120-month IST program interval, that licensee may use either the later version or the previous version. An exception to this provision would be the inclusion of a condition on the use of the Code Case that is necessary, for example, to enhance safety. Licensees who choose to continue use of the Code Case during the subsequent 120-month IST program interval will be required to implement the latest version incorporated by reference into 10 CFR 50.55a and listed in Tables 1 and 2.

Code Cases may be annulled because the provisions have been incorporated into the Code, the application for which it was specifically developed no longer exists, or experience has shown that an examination or testing method is no longer adequate. After a Code Case is annulled and 10 CFR 50.55a and this guide are amended, licensees may not implement that Code Case for the first time. However, a licensee who implemented the Code Case prior to annulment may continue to use that Code Case through the end of the present IST interval. An annulled Code Case cannot be used in the subsequent IST interval unless implemented as an approved alternative under 10 CFR 50.55a(z). If a Code Case is incorporated by reference into 10 CFR 50.55a and later annulled by the ASME because experience has shown that an examination or testing method is inadequate, the NRC will amend 10 CFR 50.55a and this guide to remove the approval of the annulled Code Case. Licensees should not begin to implement such annulled Code Cases prior to the rulemaking. Notwithstanding these requirements, the Commission may impose new or revised Code requirements, including implementation schedules, that it determines are consistent with the Backfit Rule (10 CFR 50.109).

A Code Case may be revised, for example, to incorporate user experience. The older or superseded version of the Code Case cannot be applied by the licensee or applicant for the first time. If an applicant or a licensee applied a Code Case before it was listed as superseded, the applicant or the licensee may continue to use the Code Case until the applicant or the licensee updates its construction Code of Record (in the case of an applicant, updates its application) or until the licensee’s 120-month IST update interval expires, after which the continued use of the Code Case is prohibited unless NRC approval is granted under 10 CFR Part 50.55a(z). If a Code Case is incorporated by reference into 10 CFR Part 50.55a and later a revised version is issued by the ASME because experience has shown that the design analysis, construction method, examination method, or testing method is inadequate; the NRC will amend 10 CFR Part 50.55a and the relevant RG to remove the approval of the superseded Code Case. Applicants and licensees should not begin to implement such superseded Code Cases in advance of the rulemaking.

OM Code Cases determined by the NRC to be unacceptable are listed in Regulatory Guide 1.193, “ASME Code Cases Not Approved for Use.”

With regard to the use of any Code Case, it is the responsibility of the user to make certain that the provisions of the Code Case do not conflict with regulatory requirements or licensee commitments.

C. STAFF REGULATORY GUIDANCE

For Revision 1 of Regulatory Guide 1.192, the NRC reviewed the OM Code Cases listed in the 2002 Addenda through the 2006 Addenda. Appendix A to this guide is a complete list of all OM Code Cases published by the ASME. The table in Appendix A lists the action taken by the ASME (e.g., new or revised Code Case), the edition or addenda in which the Code Case was published, and the table in the regulatory guide where each Code Case may be found. Regulatory Guide 1.192, Revision 1, supersedes the incorporation by reference of Revision 0. The Code Cases addressed by this regulatory guide are listed in three tables:

(1) Table 1, “Acceptable OM Code Cases,” lists the Code Cases that are acceptable to the NRC for implementation in the IST of light-water-cooled nuclear power plants.

(2) Table 2, “Conditionally Acceptable OM Code Cases,” lists the Code Cases that are acceptable, provided that they are used with the identified conditions (i.e., the Code Case is generally acceptable but the NRC has determined that the requirements in the Code Case, which are alternatives to the OM Code, must be supplemented in order to provide an acceptable level of quality and safety).

(3) Table 3, “OM Code Cases That Have Been Superseded by Revised Code Cases,” lists Code Cases that have been superseded through revision.

1. Acceptable Code Cases

The Code Cases listed in the table below are acceptable to the NRC for application in licensee’s IST programs. The OM Code lists revisions of Code Cases according to edition or addenda (e.g., OMN-1, 2006 Addenda), as opposed to the Boiler and Pressure Vessel Code which uses a numbering system (e.g., N‑432-1; see Regulatory Guide 1.147). Thus, the latest edition or addenda in which the Code Cases were published are listed below in accordance with the requirement in 10 CFR 50.55a that licensees or applicants implement the most recent version of a Code Case.

Table 1. Acceptable OM Code Cases

Code Case Number	Table 1 Acceptable OM Code Cases
OMN-2 (2004 Edition)	Thermal Relief Valve Code Case, OM Code-1995, Appendix I
OMN-5 (2006 Addenda)	Testing of Liquid Service Relief Valves Without Insulation
OMN-6 (2006 Addenda)	Alternate Rules for Digital Instruments
OMN-7 (2000 Addenda)	Alternative Requirements for Pump Testing
OMN-8 (2006 Addenda)	Alternative Rules for Preservice and Inservice Testing of Power-Operated Valves That Are Used for System Control and Have a Safety Function per OM-10, ISTC-1.1, or ISTA-1100
OMN-13 (2004 Edition)	Requirements for Extending Snubber Inservice Visual Examination Interval at LWR Power Plants
OMN-14 (2004 Edition)	Alternative Rules for Valve Testing Operations and Maintenance, Appendix I: BWR CRD Rupture Disk Exclusion
OMN-16 (2006 Addenda)	Use of a Pump Curve for Testing

2. Conditionally Acceptable Code Cases

The Code Cases listed in Table 2 are acceptable to the NRC for application in licensee’s IST programs within the conditions indicated by the NRC. The OM Code lists revisions of Code Cases according to edition or addenda (e.g., OMN-1, 2006 Addenda), as opposed to the Boiler and Pressure Vessel Code which uses a numbering system (e.g., N‑432-1; see Regulatory Guide 1.147). Thus, the latest edition or addenda in which the Code Cases were published are listed below in accordance with the requirement in 10 CFR 50.55a that licensees or applicants implement the most recent version of a Code Case. Unless otherwise stated, conditions imposed by the NRC are in addition to the conditions specified in the Code Case.

Table 2. Conditionally Acceptable OM Code Cases

Code Case Number	Table 2 Conditionally Acceptable OM Code Cases
	Title/Condition
OMN-1 (2006 Addenda)	Alternative Rules for Preservice and Inservice Testing of Active Electric Motor-Operated Valve Assemblies in Light-Water Reactor Power Plants
	Licensees may use Code Case OMN-1, "Alternative Rules for Preservice and Inservice Testing of Certain Electric Motor-Operated Valve Assemblies in Light-Water Reactor Power Plants," 1996 Addenda, in lieu of the provisions for stroke-time testing in Subsection ISTC of the 1995 Edition up to and including the 2006 Addenda of the ASME OM Code when applied in conjunction with the provisions for leakage rate testing in, as applicable, ISTC 4.3 (1995 Edition with the 1996 and 1997 Addenda) and ISTC-3600 (1998 Edition through the 2006 Addenda). In addition, licensees who continue to implement Section XI of the ASME BPV Code as their Code of Record may use OMN-1 in lieu of the provisions for stroke-time testing specified in Paragraph 4.2.1 of ASME/ANSI OM Part 10 as required by 10 CFR 50.55a(b)(2)(vii) subject to the conditions in this regulatory guide. Licensees who choose to apply OMN-1 must apply all its provisions. The adequacy of the diagnostic test interval for each motor-operated valve (MOV) must be evaluated and adjusted as necessary, but not later than 5 years or three refueling outages (whichever is longer) from initial implementation of OMN-1. When extending exercise test intervals for high risk MOVs beyond a quarterly frequency, licensees must ensure that the potential increase in Core Damage Frequency (CDF) and risk associated with the extension is small and consistent with the intent of the Commission’s Safety Goal Policy Statement. When applying risk insights as part of the implementation of OMN-1, licensees must categorize MOVs according to their safety significance using the methodology described in Code Case OMN-3, “Requirements for Safety Significance Categorization of Components Using Risk Insights for Inservice Testing of LWR Power Plants,” with the conditions discussed in this regulatory guide or use other MOV risk ranking methodologies accepted by the NRC on a plant specific or industry-wide basis with the conditions in the applicable safety evaluations. Note 1: As indicated at 64 FR 51370-51386, licensees are cautioned that, when implementing OMN‑1, the benefits of performing a particular test should be balanced against the potential adverse effects placed on the valves or systems caused by this testing.

Code Case Number	Table 2 Conditionally Acceptable OM Code Cases
	Title/Condition
OMN-1 (2006 Addenda) (cont’d)	Alternative Rules for Preservice and Inservice Testing of Active Electric Motor-Operated Valve Assemblies in Light-Water Reactor Power Plants
	Note 2: RG 1.192, Rev. 0, conditionally accepted Code Case OMN-11 for use in conjunction with Code Case OMN-1.  The provisions of Code Case OMN-11 were acceptably incorporated into Code Case OMN-1, 2006 Addenda, including the conditions in the RG on the use of Code Case OMN-11. Code Case OMN-11, 2006 Addenda, is therefore, no longer appropriate for use.  Accordingly, applicants and licensees choosing to perform risk-informed testing of motor-operated valves (MOVs) as allowed by RG 1.192 must do so in accordance with the applicable provisions of Code Case OMN-1 together with the conditions specified for its use in Table 2 of this regulatory guide.  In accordance with 10 CFR 50.55a(b)(6)(ii), applicants and licensees that have implemented versions of Code Cases OMN-1 and OMN-11 earlier than the 2006 Addenda (i.e., with the conditions as specified in Table 3 of this RG) may continue to use those versions through the end of the current IST interval.  If that applicant or licensee plans to continue to implement a risk-informed IST program for its MOVs in the subsequent IST interval, then OMN-1, 2006 Addenda, with the conditions specified in Table 2 of this RG will need to be implemented.
OMN-3 (2004 Edition)	Requirements for Safety Significance Categorization of Components Using Risk Insights for Inservice Testing of LWR Power Plants
	(1) In addition to those components identified in the ASME IST Program Plan, implementation of Section 1, “Applicability,” of the Code Case must include within the scope of a licensee’s risk-informed IST program non-ASME Code components categorized as high safety significant components (HSSCs) that might not currently be included in the IST Program Plan. (2) The decision criteria discussed in Section 4.4.1, “Decision Criteria,” of the Code Case for evaluating the acceptability of aggregate risk effects (i.e., for Core Damage Frequency [CDF] and Large Early Release Frequency [LERF]) must be consistent with the guidance provided in Regulatory Guide 1.174, “An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis” (Ref. 6). Section 4.4.4, “Defense in Depth,” of the Code Case must be consistent with the guidance contained in Sections 2.2.1, “Defense-in-Depth Evaluation,” and 2.2.2, “Safety Margin Evaluation,” of Regulatory Guide 1.175, “An Approach for Plant-Specific, Risk-Informed Decisionmaking: Inservice Testing” (Ref. 7). Implementation of Sections 4.5, “Inservice Testing Program,” and 4.6, “Performance Monitoring,” of the Code Case must be consistent with the guidance pertaining to inservice testing of pumps and valves provided in Section 3.2, “Program Implementation,” and Section 3.3, “Performance Monitoring,” of Regulatory Guide 1.175. Testing and performance monitoring of individual components must be performed as specified in the risk-informed components Code Cases (e.g., OMN-1, OMN-4, OMN-7, and OMN-12, as modified by the conditions discussed in this regulatory guide).
Code Case Number	Table 2 Conditionally Acceptable OM Code Cases
	Title/Condition
OMN-3 (2004 Edition) (cont’d)	Requirements for Safety Significance Categorization of Components Using Risk Insights for Inservice Testing of LWR Power Plants
	Implementation of Section 3.2, “Plant Specific PRA,” of the Code Case must be consistent with the guidance that the Owner is responsible for demonstrating and justifying the technical adequacy of the probabilistic risk assessment (PRA) analyses used as the basis to perform component risk ranking and for estimating the aggregate risk impact. Regulatory Guide 1.200, “An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities,” (Ref. 8) provides guidance for determining the technical adequacy of the PRA used in a risk-informed regulatory activity. Regulatory Guide 1.201, “Guidelines for Categorizing Structures, Systems, and Components in Nuclear Power Plants According to their Safety Significance,” (Ref. 9) describes one acceptable method to categorize the safety significance of an active component, including methods to use when a plant-specific PRA that meets the appropriate Regulatory Guide 1.200 capability for specific hazard group(s) (e.g., seismic and fire) is not available. Section 4.2.4, “Reconciliation,” paragraph (b), is not endorsed. The expert panel may not classify components that are ranked HSSC by the results of a qualitative or quantitative PRA evaluation (excluding the sensitivity studies) or the defense-in-depth assessment to low safety significant component (LSSC). Implementation of Section 3.3, “Living PRA,” must be consistent with the following: (1) To account for potential changes in failure rates and other changes that could affect the PRA, changes to the plant must be reviewed, and, as appropriate, the PRA updated; (2) When the PRA is updated, the categorization of structures, systems, and components must be reviewed and changed if necessary to remain consistent with the categorization process; and (3) The review of plant changes must be performed in a timely manner and must be performed once every two refueling outages or as required by 10 CFR 50.71(h)(2) for combined license holders. Note 1: The Code Case methodology for risk ranking uses two categories of safety significance. The NRC staff has determined that this is acceptable for ranking all component types. However, the NRC staff has accepted other methodologies for risk ranking MOVs, with certain conditions, that use three categories of safety significance.
OMN-4 (2004 Edition)	Requirements for Risk Insights for Inservice Testing of Check Valves at LWR Power Plants
	(1) Valve opening and closing functions must be demonstrated when flow testing or examination methods (nonintrusive, or disassembly and inspection) are used. (2) The initial interval for tests and associated examinations may not exceed two fuel cycles or 3 years, whichever is longer; any extension of this interval may not exceed one fuel cycle per extension with the maximum interval not to exceed 10 years. Trending and evaluation of existing data must be used to reduce or extend the time interval between tests. (3) If the Appendix II condition monitoring program is discontinued, the requirements of ISTC 4.5.1, “Exercising Test Frequency,” through ISTC 4.5.4, “Valve Obturator Movement,” (1996 and 1997 Addenda) or ISTC 3510, 3520, 3540, and 5221 (1998 Edition with the 1999 and 2000 Addenda), as applicable, must be implemented. Note 1: The conditions with respect to allowable methodologies for OMN-3 risk ranking specified for the use of OMN-1 also apply to OMN-4.

Code Case Number	Table 2 Conditionally Acceptable OM Code Cases
	Title/Condition
OMN-9 (2004 Edition)	Use of a Pump Curve for Testing
	(1) When a reference curve may have been affected by repair, replacement, or routine servicing of a pump, a new reference curve must be determined, or an existing reference curve must be reconfirmed, in accordance with Section 3 of this Code Case. (2) If it is necessary or desirable, for some reason other than that stated in Section 4 of this Code Case, to establish an additional reference curve or set of curves, these new curves must be determined in accordance with Section 3.
OMN-12 (2004 Edition)	Alternative Requirements for Inservice Testing Using Risk Insights for Pneumatically and Hydraulically Operated Valve Assemblies in Light-Water Reactor Power Plants (OM-Code 1998, Subsection ISTC)
	(1) Paragraph 4.2, “Inservice Test Requirements,” of OMN‑12 specifies inservice test requirements for pneumatically and hydraulically operated valve assemblies categorized as high safety significant within the scope of the Code Case. The inservice testing program must include a mix of static and dynamic valve assembly performance testing. The mix of valve assembly performance testing may be altered when justified by an engineering evaluation of test data. Paragraph 4.2.2.3 of OMN‑12 specifies the periodic test requirements for pneumatically and hydraulically operated valve assemblies categorized as high safety significant within the scope of the code case. The adequacy of the diagnostic test interval for each high safety significant valve assembly must be evaluated and adjusted as necessary, but not later than 5 years or three refueling outages (whichever is longer) from initial implementation of OMN-12. Paragraph 4.2.3, “Periodic Valve Assembly Exercising,” of OMN‑12 specifies periodic exercising for pneumatically and hydraulically operated valve assemblies categorized as high safety significant within the scope of the code case. Consistent with the requirement in OMN‑3 to evaluate the aggregate change in risk associated with changes in test strategies, when extending exercise test intervals for high safety significant valve assemblies beyond a quarterly frequency, the potential increase in Core Damage Frequency (CDF) and risk associated with the extension must be evaluated and determined to be small and consistent with the intent of the Commission’s Safety Goal Policy Statement. (4) Paragraph 4.4.1, “Acceptance Criteria,” of OMN‑12 specifies that acceptance criteria must be established for the analysis of test data for pneumatically and hydraulically operated valve assemblies categorized as high safety significant within the scope of the Code Case. When establishing these acceptance criteria, the potential degradation rate and available capability margin for each valve assembly must be evaluated and determined to provide assurance that the valve assemblies are capable of performing their design‑basis functions until the next scheduled test. (5) Paragraph 5, “Low Safety Significant Valve Assemblies,” of OMN‑12 specifies that the purpose of its provisions is to provide a high degree of confidence that pneumatically and hydraulically operated valve assemblies categorized as low safety significant within the scope of the Code Case will perform their intended safety function if called upon. The licensee must have reasonable confidence that low safety significant valve assemblies remain capable of performing their intended design-basis safety functions until the next scheduled test. The test and evaluation methods may be less rigorous than those applied to high safety significant valve assemblies.
Code Case Number	Table 2 Conditionally Acceptable OM Code Cases
	Title/Condition
OMN-12 (2004 Edition) (cont’d)	Alternative Requirements for Inservice Testing Using Risk Insights for Pneumatically and Hydraulically Operated Valve Assemblies in Light-Water Reactor Power Plants (OM-Code 1998, Subsection ISTC)
	Paragraph 5.1, “Set Points and/or Critical Parameters,” of OMN‑12 specifies requirements and guidance for establishing set points and critical parameters of pneumatically and hydraulically operated valve assemblies categorized as low safety significant within the scope of the Code Case. Setpoints for these valve assemblies must be based on direct dynamic test information, a test‑based methodology, or grouping with dynamically tested valves, and documented according to Paragraph 5.1.4. The setpoint justification methods may be less rigorous than provided for high risk significant valve assemblies. Paragraph 5.4, “Evaluations,” of OMN-12, specifies evaluations to be performed of pneumatically and hydraulically operated valve assemblies categorized as low safety significant within the scope of the Code Case. Initial and periodic diagnostic testing must performed to establish and verify the setpoints of these valve assemblies to ensure that they are capable of performing their design-basis safety functions. Methods for testing and establishing test frequencies may be less rigorous than applied to high risk significant valve assemblies. Paragraph 5.6, “Corrective Action,” of OMN-12 specifies that corrective action must be initiated if the parameters monitored and evaluated for pneumatically and hydraulically operated valve assemblies categorized as low safety significant within the scope of the Code Case do not meet the established criteria. Further, if the valve assembly does not satisfy its acceptance criteria, the operability of the valve assembly must be evaluated. Note 1: Licensees are cautioned that, when implementing OMN-12, the benefits of performing a particular test should be balanced against the potential adverse effects placed on the valves or systems caused by this testing. Note 2: Paragraph 3.1 of OMN-12 states that “Valve assemblies shall be classified as either high safety significant or low safety significant in accordance with Code Case OMN-3.” This note as well as Note 2 to OMN-4 have been added to ensure the consistent consideration of risk insights.

3. Code Cases Superseded by Revised Code Cases

Table 3 lists Code Cases that have been superseded by revision.

Table 3. OM Code Cases That Have Been Superseded by Revised Code Cases

Code Case Number	Table 3 Code Cases That Have Been Superseded by Revised Code Cases
OMN-1 (1996 Addenda) (1999 Addenda) (2001 Edition) (2002 Addenda) (2004 Edition)	Alternative Rules for Preservice and Inservice Testing of Certain Motor-Operated Valve Assemblies in Light-Water Reactor Power Plants (OM Code-1995, Subsection ISTC)
	Licensees may use this Code Case in lieu of the provisions for stroke‑time testing in Subsection ISTC of the 1995 Edition up to and including the 2000 Addenda of the ASME OM Code when applied in conjunction with the provisions for leakage rate testing in, as applicable, ISTC 4.3 (1995 Edition with the 1996 and 1997 Addenda) and ISTC‑3600 (1998 Edition through the 2004 Addenda). In addition, licensees who continue to implement Section XI of the ASME BPV Code as their Code of Record may use OMN-1 in lieu of the provisions for stroke-time testing specified in Paragraph 4.2.1 of ASME/ANSI OM Part 10 as required by 10 CFR 50.55a(b)(2)(vii) subject to the conditions in this regulatory guide. Licensees who choose to apply OMN‑1 must apply all its provisions. The adequacy of the diagnostic test interval for each motor-operated valve (MOV) must be evaluated and adjusted as necessary, but not later than 5 years or three refueling outages (whichever is longer) from initial implementation of OMN‑1. (2) When extending exercise test intervals for high risk MOVs beyond a quarterly frequency, licensees must ensure that the potential increase in Core Damage Frequency (CDF) and risk associated with the extension is small and consistent with the intent of the Commission’s Safety Goal Policy Statement. (3) When applying risk insights as part of the implementation of OMN-1, licensees must categorize MOVs according to their safety significance using the methodology described in Code Case OMN-3, “Requirements for Safety Significance Categorization of Components Using Risk Insights for Inservice Testing of LWR Power Plants,” with the conditions discussed in this regulatory guide or use other MOV risk-ranking methodologies accepted by the NRC on a plant-specific or industry-wide basis with the conditions in the applicable safety evaluations. NOTE: As indicated at 64 FR 51370-51386, licensees are cautioned that, when implementing OMN-1, the benefits of performing a particular test should be balanced against the potential adverse effects placed on the valves or systems caused by this testing.
OMN-2 (1998 Addenda) (2001 Edition)	Thermal Relief Valve Code Case, OM Code-1995, Appendix I
OMN-3 (1998 Edition) (2001 Edition) (2002 Addenda)	Requirements for Safety Significance Categorization of Components Using Risk Insights for Inservice Testing of LWR Power Plants
	In addition to those components identified in the ASME IST Program Plan, implementation of Section 1, “Applicability,” of the Code Case must include within the scope of a licensee’s risk-informed IST program non-ASME Code components categorized as high safety significant components (HSSCs) that might not currently be included in the IST Program Plan. The decision criteria discussed in Section 4.4.1, “Decision Criteria,” of the Code Case for evaluating the acceptability of aggregate risk effects (i.e., for Core Damage Frequency [CDF] and Large Early Release Frequency [LERF]) must be consistent with the guidance provided in Regulatory Guide 1.174, “An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis.” Section 4.4.4, “Defense in Depth,” of the Code Case must be consistent with the guidance contained in Sections 2.2.1, “Defense-in-Depth Evaluation,” and 2.2.2, “Safety Margin Evaluation,” of Regulatory Guide 1.175, “An Approach for Plant-Specific, Risk-Informed Decisionmaking: Inservice Testing.” Implementation of Sections 4.5, “Inservice Testing Program,” and 4.6, “Performance Monitoring,” of the Code Case must be consistent with the guidance pertaining to inservice testing of pumps and valves provided in Section 3.2, “Program Implementation,” and Section 3.3, “Performance Monitoring,” of Regulatory Guide 1.175. Testing and performance monitoring of individual components must be performed as specified in the risk-informed components Code Cases (e.g., OMN-1, OMN-4, OMN-7, and OMN-12, as modified by the conditions discussed in this regulatory guide). Note: The Code Case methodology for risk ranking uses two categories of safety significance. The NRC staff has determined that this is acceptable for ranking MOVs, air-operated valves (AOVs), and check valves. However, the NRC staff has accepted other methodologies for risk ranking MOVs, with certain conditions, that use three categories of safety significance.
OMN-4 (1999 Addenda) (2001 Edition)	Requirements for Risk Insights for Inservice Testing of Check Valves at LWR Power Plants
	(1) Valve opening and closing functions must be demonstrated when flow testing or examination methods (nonintrusive, or disassembly and inspection) are used. (2) The initial interval for tests and associated examinations may not exceed two fuel cycles or 3 years, whichever is longer; any extension of this interval may not exceed one fuel cycle per extension with the maximum interval not to exceed 10 years. Trending and evaluation of existing data must be used to reduce or extend the time interval between tests. (3) If the Appendix II condition monitoring program is discontinued, the requirements of ISTC 4.5.1, “Exercising Test Frequency,” through ISTC 4.5.4, “Valve Obturator Movement,” (1996 and 1997 Addenda) or ISTC 3510, 3520, 3540, and 5221 (1998 Edition with the 1999 and 2000 Addenda), as applicable, must be implemented.
OMN-5 (1999 Addenda) (2001 Edition) (2004 Edition)	Testing of Liquid Service Relief Valves Without Insulation
OMN-6 (1999 Addenda) (2001 Edition) (2002 Addenda) (2004 Edition)	Alternate Rules for Digital Instruments
OMN-7 (2000 Addenda) (2001 Edition) (2002 Addenda) (2004 Edition) (2005 Addenda)	Alternative Requirements for Pump Testing
OMN-8 (2000 Addenda) (2001 Edition) (2003 Addenda) (2004 Edition) (2005 Addenda)	Alternative Rules for Preservice and Inservice Testing of Power-Operated Valves That Are Used for System Control and Have a Safety Function per OM‑10, ISTC-1.1, or ISTA-1100
OMN-9 (2000 Addenda) (2001 Edition) (2003 Addenda)	Use of a Pump Curve for Testing
	(1) When a reference curve may have been affected by repair, replacement, or routine servicing of a pump, a new reference curve must be determined, or an existing reference curve must be reconfirmed, in accordance with Section 3 of this Code Case. (2) If it is necessary or desirable, for some reason other than that stated in Section 4 of this Code Case, to establish an additional reference curve or set of curves, these new curves must be determined in accordance with Section 3.
OMN-11 (2001 Edition) (2003 Addenda) (2004 Edition)	Risk-Informed Testing for Motor-Operated Valves
	Where a licensee is implementing Code Case OMN-1 as a justified alternative to the requirements for stroke-time testing of motor-operated valves (MOVs) in Subsection ISTC of the ASME OM Code, the licensee may apply risk insights to its MOV program as indicated in Paragraph 3.7, “Risk Based Criteria for MOV Testing,” of OMN-1 and as supplemented by Code Case OMN‑11 with the following conditions: In addition to the Inservice Testing provisions of Paragraph 3 of OMN-11, MOVs within the scope of OMN‑1 that are categorized as Low Safety Significant Components (LSSCs) must satisfy the other provisions of OMN-1, including determination of proper MOV test intervals as specified in Paragraph 6 of OMN‑1.
OMN-11 (2001 Edition) (2003 Addenda) (2004 Edition) (continued)	Risk-Informed Testing for Motor-Operated Valves
	Paragraph 3(a) of OMN‑11 must be interpreted as allowing the provisions of Paragraphs 3.5(a) and (d) of OMN‑1 related to similarity and test sample, respectively, to be relaxed for the grouping of LSSC MOVs. The provisions of Paragraphs 3.5(b), (c), and (e) of OMN-1, related to evaluation of test results for MOVs in the group, sequential testing of a representative MOV, and analysis of test results per Paragraph 6 of OMN-1 for each MOV in the group, respectively, continue to be applicable to all MOVs within the scope of OMN‑1. When extending exercise test intervals for high risk MOVs beyond a quarterly frequency, the licensee must ensure that the potential increase in CDF and risk associated with the extension is small and consistent with the intent of the Commission’s Safety Goal Policy Statement. Note 1: Condition regarding allowable methodologies for MOV risk ranking specified for the use of OMN-1 also applies to OMN-11.
OMN-12 (2001 Edition)	Alternative Requirements for Inservice Testing Using Risk Insights for Pneumatically and Hydraulically Operated Valve Assemblies in Light-Water Reactor Power Plants (OM-Code 1998, Subsection ISTC)
	Paragraph 4.2, “Inservice Test Requirements,” of OMN‑12 specifies inservice test requirements for pneumatically and hydraulically operated valve assemblies categorized as high safety significant within the scope of the Code Case. The inservice testing program must include a mix of static and dynamic valve assembly performance testing. The mix of valve assembly performance testing may be altered when justified by an engineering evaluation of test data. Paragraph 4.2.2.3 of OMN‑12 specifies the periodic test requirements for pneumatically and hydraulically operated valve assemblies categorized as high safety significant within the scope of the Code Case. The adequacy of the diagnostic test interval for each high safety significant valve assembly must be evaluated and adjusted as necessary, but not later than 5 years or three refueling outages (whichever is longer) from initial implementation of OMN-12. Paragraph 4.2.3, “Periodic Valve Assembly Exercising,” of OMN‑12 specifies periodic exercising for pneumatically and hydraulically operated valve assemblies categorized as high safety significant within the scope of the Code Case. Consistent with the requirement in OMN‑3 to evaluate the aggregate change in risk associated with changes in test strategies, when extending exercise test intervals for high safety significant valve assemblies beyond a quarterly frequency, the potential increase in Core Damage Frequency (CDF) and risk associated with the extension must be evaluated and determined to be small and consistent with the intent of the Commission’s Safety Goal Policy Statement.
OMN-12 (2001 Edition) (continued)	Alternative Requirements for Inservice Testing Using Risk Insights for Pneumatically and Hydraulically Operated Valve Assemblies in Light-Water Reactor Power Plants OM-Code 1998, Subsection ISTC)
	(4) Paragraph 4.4.1, “Acceptance Criteria,” of OMN‑12 specifies that acceptance criteria must be established for the analysis of test data for pneumatically and hydraulically operated valve assemblies categorized as high safety significant within the scope of the Code Case. When establishing these acceptance criteria, the potential degradation rate and available capability margin for each valve assembly must be evaluated and determined to provide assurance that the valve assemblies are capable of performing their design‑basis functions until the next scheduled test. (5) Paragraph 5, “Low Safety Significant Valve Assemblies,” of OMN‑12 specifies that the purpose of its provisions is to provide a high degree of confidence that pneumatically and hydraulically operated valve assemblies categorized as low safety significant within the scope of the Code Case will perform their intended safety function if called upon. The licensee must have reasonable confidence that low safety significant valve assemblies remain capable of performing their intended design-basis safety functions until the next scheduled test. The test and evaluation methods may be less rigorous than those applied to high safety significant valve assemblies. (6) Paragraph 5.1, “Set Points and/or Critical Parameters,” of OMN‑12 specifies requirements and guidance for establishing set points and critical parameters of pneumatically and hydraulically operated valve assemblies categorized as low safety significant within the scope of the Code Case. Setpoints for these valve assemblies must be based on direct dynamic test information, a test‑based methodology, or grouping with dynamically tested valves, and documented according to Paragraph 5.1.4. The setpoint justification methods may be less rigorous than provided for high risk significant valve assemblies. (7) Paragraph 5.4, “Evaluations,” of OMN-12 specifies evaluations to be performed of pneumatically and hydraulically operated valve assemblies categorized as low safety significant within the scope of the Code Case. Initial and periodic diagnostic testing must be performed to establish and verify the setpoints of these valve assemblies to ensure that they are capable of performing their design-basis safety functions. Methods for testing and establishing test frequencies may be less rigorous than applied to high risk significant valve assemblies. (8) Paragraph 5.6, “Corrective Action,” of OMN-12 specifies that corrective action must be initiated if the parameters monitored and evaluated for pneumatically and hydraulically operated valve assemblies categorized as low safety significant within the scope of the Code Case do not meet the established criteria. Further, if the valve assembly does not satisfy its acceptance criteria, the operability of the valve assembly must be evaluated. Note: Licensees are cautioned that, when implementing OMN-12, the benefits of performing a particular test should be balanced against the potential adverse effects placed on the valves or systems caused by this testing.
OMN-13 (2001 Edition)	Requirements for Extending Snubber Inservice Visual Examination Interval at LWR Power Plants
OMN-14 (2003 Addenda)	Alternative Rules for Valve Testing Operations and Maintenance, Appendix I: BWR CRD Rupture Disk Exclusion

D. IMPLEMENTATION

The purpose of this section is to provide information to applicants and licensees regarding the NRC staff’s plans for using this regulatory guide. The requirements addressing implementation of OM Code Cases are contained in 10 CFR 50.55a(b)(6). No backfitting is intended or approved in connection with the issuance of this guide.

REGULATORY ANALYSIS

A separate regulatory analysis was not prepared for this regulatory guide. The regulatory basis for this guide is the regulatory analysis prepared for the amendment to 10 CFR 50.55a, “Codes and Standards,” which incorporates this regulatory guide by reference.

REFERENCES¹

1. ASME Code for Operation and Maintenance of Nuclear Power Plants, American Society of Mechanical Engineers, New York, NY.²

2. Code of Federal Regulations, Title 10, Energy, Part 50, “Domestic Licensing of Production and Utilization Facilities” (10 CFR Part 50), U.S. Nuclear Regulatory Commission, Washington, DC.

3. Regulatory Guide 1.84, “Design, Fabrication, and Materials Code Case Acceptability, ASME Section III,” U.S. Nuclear Regulatory Commission, Washington, DC.

4. Regulatory Guide 1.147, “Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1,” U.S. Nuclear Regulatory Commission, Washington, DC.

5. Regulatory Guide 1.193, “ASME Code Cases Not Approved for Use,” U.S. Nuclear Regulatory Commission, Washington, DC.

6. Regulatory Guide 1.174, “An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis,” U.S. Nuclear Regulatory Commission, Washington, DC.

7. Regulatory Guide 1.175, “An Approach for Plant-Specific, Risk-Informed Decisionmaking: Inservice Testing,” U.S. Nuclear Regulatory Commission, Washington, DC.

8. Regulatory Guide 1.200, “An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities,” U.S. Nuclear Regulatory Commission, Washington, DC.

9. Regulatory Guide 1.201, “Guidelines for Categorizing Structures, Systems, and Components in Nuclear Power Plants According to their Safety Significance,” U.S. Nuclear Regulatory Commission, Washington, DC.

APPENDIX A

NUMERICAL LISTING OF OPERATION AND MAINTENANCE

CODE CASES

Code Case	ASME Action Regarding Version of Code Case	Revision/Table
OMN-1	New Reaffirmed1 Reaffirmed Revised Reaffirmed Revised	1996 Addenda2 [T3]3 1999 Addenda4 [T3] 2001 Edition5 [T3] 2002 Addenda6 [T3] 2004 Edition6 [T3] 2006 Addenda [T2]
OMN-2	New Reaffirmed Reaffirmed	1998 Edition4 [T3] 2001 Edition5 [T3] 2004 Edition5 [T1]
OMN-3	New Reaffirmed Revised Reaffirmed	1998 Edition4 [T3] 2001 Edition5 [T3] 2002 Addenda6 [T3] 2004 Edition [T2]
OMN-4	New Reaffirmed Reaffirmed	1999 Addenda4 [T3] 2001 Edition5 [T3] 2004 Edition5 [T2]
OMN-5	New Reaffirmed Reaffirmed Reaffirmed	1999 Addenda4 [T3] 2001 Edition5 [T3] 2004 Edition5 [T3] 2006 Addenda5 [T1]
OMN-6	New Reaffirmed Reaffirmed Reaffirmed Revised	1999 Addenda4 [T3] 2001 Edition5 [T3] 2002 Addenda5 [T3] 2004 Edition5 [T3] 2006 Addenda [T1]
OMN-7	New Reaffirmed Reaffirmed Reaffirmed Reaffirmed Reaffirmed	2000 Addenda4 [T3] 2001 Edition5 [T3] 2002 Addenda5 [T3] 2004 Edition5 [T3] 2005 Addenda5 [T3] 2006 Addenda5 [T1]
OMN-8	New Reaffirmed Reaffirmed Reaffirmed Reaffirmed Revised	2000 Addenda4 [T3] 2001 Edition5 [T3] 2003 Addenda5 [T3] 2004 Edition5 [T3] 2005 Addenda5 [T3] 2006 Addenda [T1]
OMN-9	New Reaffirmed Reaffirmed Reaffirmed	2000 Addenda4 [T3] 2001 Edition5 [T3] 2003 Addenda5 2004 Edition5 [T2]
OMN-107	New Reaffirmed Reaffirmed Reaffirmed Reaffirmed	2000 Addenda 2001 Edition 2003 Addenda 2004 Edition 2006 Addenda
OMN-11	New Reaffirmed Reaffirmed Reaffirmed	2001 Edition4 [T3] 2003 Addenda5 [T3] 2004 Edition5 [T3] 2006 Addenda8
OMN-12	New Reaffirmed	2001 Edition4 [T3] 2004 Edition5 [T2]
OMN-13	New Reaffirmed	2001 Edition4 [T3] 2004 Edition5 [T1]
OMN-14	New Reaffirmed	2003 Addenda [T3] 2004 Edition [T1]
OMN-157	New Revised	2004 Edition 2006 Addenda
OMN-16	New	2006 Addenda [T1]

2¹ Publicly available NRC published documents are available electronically through the NRC Library on the NRC’s public Web site at: http://www.nrc.gov/reading-rm/doc-collections/. The documents can also be viewed on-line or printed for a fee in the NRC’s Public Document Room (PDR) at 11555 Rockville Pike, Rockville, MD; the mailing address is USNRC PDR, Washington, DC 20555; telephone 301-415-4737 or (800) 397-4209; fax (301) 415-3548; and e-mail pdr.resource@nrc.gov. 

² Copies may be purchased from the American Society of Mechanical Engineers, Three Park Avenue, New York, NY 10016-5990; phone (212) 591-8500; fax (212) 591-8501; www.asme.org.

1 Note: In some cases, clarifications or editorial changes were made in reaffirmed Code Cases, and notations regarding where those changes occurred may not have been provided with the Code Case.

2 This version of the Code Case was superseded by a subsequent revision and was not considered for approval in RG 1.192, Revision 0. Therefore, this version of the Code Case is not approved for use.

3 [T3] is Table 3 in the regulatory guide, “Code Cases That Have Been Superseded by Revised Code Cases”

4 This version of the Code Case was approved for use in RG 1.192, Revision 0, June 2003.

5 RG 1.192 approved a specific version of this Code Case based on edition or addenda. Licensees may have updated procedures and listed a later reaffirmed version of the Code Case based on the ASME finding that the versions are essentially equivalent. The NRC has determined that the use of the later reaffirmed version is acceptable. Licensees are expected to comply with 10 CFR 50.55a, however, when updating their IST programs (e.g., implement the latest version approved in RG 1.192).

6 Code Case OMN-1 was revised in 2002 Addenda, i.e., changes were not considered to be clarifications or editorial. Code Case OMN-1, 2002 Addenda, and subsequent reaffirmations (OMN-1, 2004 Edition) are not approved in RG 1.192 for generic use. Additionally, Code Case OMN-3, 2003 Addenda, is a revision and therefore is not generically approved for use in RG 1.192.

7 Code Cases OMN-10 and OMN-15 were not approved for use and are listed in RG 1.193.

8 Code Case OMN-11, 2006 Addenda, is no longer applicable. The requirements in the Code Case were merged into Code Case OMN-1, 2006 Addenda.

2