ML20147E444
| ML20147E444 | |
| Person / Time | |
|---|---|
| Issue date: | 03/04/1997 |
| From: | Callan L NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | |
| References | |
| SECY-97-055, SECY-97-055-R, SECY-97-55, SECY-97-55-R, NUDOCS 9703070146 | |
| Download: ML20147E444 (37) | |
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l POLICY ISSUE (Information)
March 4, 1997 SECY-97-055 FOR:
The Commissioners FROM:
L. Joseph Callan Executive Director for Operations
SUBJECT:
MAINTENANCE RULE STATUS, RESULTS, AND LESSONS LEARNED PURPOSE:
To inform the Commission about:
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The background of the maintenance rule.
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The status and resu"s of the NRC staff a +ivities related to the maintenance ruja,
. including revising the maintenance rule regulatory guide.
3.
Lessons learned from the implementation and initial baseline inspections of the maintenance rule.
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Insights gained from the NRC staffs experience with the maintenance rule to consider when developing other risk-informed, performance-based rules.
SUMMARY
Since the effective date of the maintenance rule in July 1996, the NRC staff has completed 18 maintenance rule baseline inspections and revised the applicable regulatory guide. On the basis of the NRC staffs findings to date, the implementation, inspection, and enforcement of the maintenance rule have been successful. Concems have been identified, but l
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Contact:
SECY NOTE:
TO BE MADE PUBLICLY Thomas Bergman, NRR (301) 415-1021 3
AVAILABLE AT COMMISSION MEETING ON MARCH 10, 1997
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overall, licensees inspected to date have adequately implemented the rule. Moreover, the lessons learned from the implementation, inspection and enforcement of the maintenance rule should benefit the development of other risk-informed, performance-based regulations.
The remaining maintenance rule activities the NRC staff has planned include: completing the baseline inspection program, issuing an information notice of lessons leamed from the early l
' baseline inspections, revising the baseline inspection procedure to reflect lessons leamed and revising the implementation guidance documents.
BACKGROUND:
in the 1980s, the NRC became concemed about the number of transients and scrams initiated as a result of problems with balance of plant systems and components. Since most of this equipment was not addressed under existing regulations, the NRC evaluated whether i
j a maintenance rule was necessary. As a result of NRC staff activities, in particular the 1
maintenance team inspections, the NRC decided that the need for such a rule existed. The
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NRC's determination rested primarily on the conclusion that proper maintenance is essential l
- to plant safety, and that there is a clear link between effective maintenance and safety as it relates to such factors as the number of transients and challenges to safety systems and the l
associated need for operability, availability and reliability of safety equipment. In addition, j-good maintenance is also important in providing assurance that failures of other than safety-related simctures, systems, and components (SSCs) that could initiate or adversely affect a i
j transiept or accident are minimized. On the basis of these conclusions, the NRC developed a risk-informed, performance-based maintenance rule that addressed both safety-related and j
certain nonsafety-related SSCs.
The maintenance rule,10 CFR 50.65, " Requirements for monitoring the effectiveness of ~
maintenance at nuclear power plants," was issued on July 10,1991, to be effective on
' July 10,1996. The text of the rule is brief, containing the basic requirements for the activities j
that licensees need to accomplish to monitor maintenance effectiveness. Implementation i
guidance was developed by the Nuclear Management and Resources Council (NUMARC,
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now the Nuclear Energy institute (NEI)), resulting in NUMARC 93-01, "Indus'try Guideline for
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Monitoring the Effectiveness of Maintenance at Nuclear Power Plants." The staff endorsed
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j this guideline, with clarifications, in Regulatory Guide 1.160, " Monitoring the Effectiveness of j
Maintenance at Nuclear Power Plants." Together, NUMARC 93-01 and RG 1.160 provide sufficient guidance for licensees to develop a program that can comply with the requirements i
of the maintenance rule, though other methods may also be acceptable.
1 Reauirements'of the Maintenance Rule The maintenance rule itself is simple and brief. Specifically, it consists of requirements that j
establish which structures, systems and components (SSCs) are included within the scope of the rule, requirements for monitoring the performance or condition of those SSCs within the
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scope of the rule, and a requirement that licensees periodically assess the effectiveness of
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i maintenance. The rule also encourages licensees to consider the impact on safety when removing equipment from service for preventive maintenance.
i Paragraph (b) of 10 CFR 50.65 establishes the scoping criteria for the maintenance rule.
j The scope of the rule includes all the SSCs that are safety-related, and those nonsafety-
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l related SSCs that are: 1) relied upon to mitigate accidents or transients or are used in emergency operating procedures (EOPs),2) whose failure could prevent safety-related SSCs i
from fulfilling their safety functions, or 3) whose failure could cause a reactor scram or an j
actuation of a safety-related system.
l Paragraph (a)(1) of the maintenance rule requires licensees to monitor the performance or
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' condition of SSCs within the scope of the rule against licensee-established goals to provide j
i reasonable assurance that these SSCs are capable of fulfilling their intended functions.
l These goals are to be commensurate with safety and, where practical, should take into
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account industry-wide operating experience. Paragraph (a)(1) also requires licensees to take appropriate corrective actions when the performance of an SSC does not meet established l
goals.'
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Paragraph (a)(2) of 10 CFR 50.65 allows licensees to eliminate the goal setting and l
monitoring activities specified in Paregraph (a)(1) where the licensee has denionstrated that the performance or condition of SSCs is effectively controlled through preventive j
maintenance.
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Paragraph (a)(3) of the maintenance rule has two parts. First, it requires that licensees 1
periodically evaluate their performance and condition monitoring activities and associated goals, as well as preventive maintenance activities, at least once each refueling cycle not to i
exceed 24 months between evaluations. Where practical, the evaluations are required to take into account industry-wide operating experience. Licensees are to make adjustments in 4
their programs where necessary to ensure that the objective of preventing failures of SSCs through maintenance is appropriately balanced against the objective of minimizing j
unavailability of SSCs due to monitoring or preventive maintenance. The second part of Paragraph (a)(3) states that licensees should take into account the total plant equipment that is out of service in order to determine the overall effect on performance of safety functions when performing monitoring and preventive maintenance activities. Because this provision i
states "should," licensees are not required to perform the safety assessments, i
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Implementation Guidance Document Devetooment 4
j Soon after the rule was issued, the NRC staff and NUMARC concurrently began to develop i
implementation guidance. After it became apparent that NUMARC's proposed j
implementation guidance, NUMARC 93-01, would be an acceptable method for implementing j
' Paragraph (a)(1) of the maintenance rule was amended on August 28,1996, to require
. plants undergoing decommissioning or decommissioned to include within scope only those j
SSCs associated with storing, controlling, and maintaining spent fuel in a safe condition.
4 the rule, the NRC staff determined that NUMARC 93-01 could be endorsed in a regulatory-guide.
After developing NUMARC 93-01, industry conducted a verification and validation (V&V) program that was observed by the NRC staff. The purpose of the industry's V&V program was to evaluate the adequacy of NUMARC 93-01 and make changes to NUMARC 93-01 where necessary. After incorporating the changes, NUMARC issued NUMARC 93-01, Revision 0, in May 1993. The NRC staff then endorsed NUMARC 93-01, Revision 0, in RG 1.160, Revision 0, in June 1993.
Between September 1994 and March 1995, the NRC staff conducted a pilot site visit program (also referred to as the pilot program) at nine volunteer sites. The purpose of this pilot program was to confirm that the draft maintenance rule inspection procedure (IP), which was issueo by the NRC staff in December 1993, could be used to verify that licensees who implemented the maintenance rule in accordance with RG 1.160 and NUMARC 93-01 were in compliance with the rule. The NRC staff documented the results of these pilot site visits in site-specific reports and in NUREG-1526, " Lessons Leamed from Early implementation of the Mair<enance Rule at Nine Nuclear Power Plants" (June 1995). On the basis of lessons leamed during the pilot site visrc, workshops held with industry, and public meetings, the NRC staff revised the draft inspectiott procedure and issued the revision as IP 62706,
" Maintenance Rule," on August 31,1995. On the basis of similar information, NEl issued NUMARC 93-01, Revision 2, in April 1996.
The' staff then considered endorsing NUMARC 93-01, Revision 2, and issued Draft Regulatory Guide (DG) 1051, " Monitoring the Effectiveness of Maintenance at Nuclear Power Plants," for public comment in August 1996. After the public comment period expired (November 15,1996), the NRC staff incorporated the appropriate comments and further clarified NUMARC 93-01, Revision 2, on the basis of comments received in public meetings and during maintenance rule baseline inspections conducted since the effective date of the rule. Then, in February 1997, the NRC staff completed its endorsement and clarifications of NUMARC 93-01, Revision 2, in RG 1.160, Revision 2 (attached).2 Imolementina the Maintenance Rule Usina NUMARC 93-01 When implementing the maintenance rule using NUMARC 93-01,8 a licensee first uses the criteria in 10 CFR 50.65(b) to determine which SSCs are within the scope of the rule. The licensee then categorizes all of the SSCs within the scope of the rule as being either of high '
'RG 1.160, Revision 2, has been approved by NRR. The RG has been endorsed by the Committee to Review Generic Requirements and the Office of General Counsel has no legal objection. The RG will be published and distributed in March 1997.
'As of February 14,1997, all licensees that participated in the pilot program (9 sites) or that have been inspected by the NRC staff as part of the maintenance rule baseline inspection program (18 sites) implemented the rule using RG 1.160 and NUMARC 93-01.
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i or low safety significance. ' It is important to emphasize that scoping is accomplished solely using the deterministic criteria in Paragraph (b) of the rule. Safety (risk) is only considered i
after the scope has been established.
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SSCs that are of high safety significance must be monitored at the system, train, or component level; at a minimum, this monitoring must include SSC reliability and availability.
SSCs that are of low safety significance and in standby must also be monitored at the system, train, or component level; at a minimum this monitoring must include reliability.
SSCs that are of low safety significance and normally operating may be monitored at the l
plant level; this monitoring typically includes unplanned scrams, unplanned safety system actuations and unplanned capability loss factor.
Except for those SSCs determined to be inherently reliable or that can be run to failure, the SSC will be monitored in accordance with either Paragraph (a)(1) or Paragraph (a)(2) of the rule on the basis of performance. Those SSCs that have demonstrated effective preventive maintenance are monitored in accordance with Paragraph (a)(2), as allowed by the rule.
SSCs monitored in accordance with Paragraph (a)(2) must have appropriate performance criteria' established. Those SSCs for which the licensee cannot demonstrate effective preventive maintenance are monitored in accordance with Paragraph (a)(1). SSCs monitored under Paragraph (a)(1) must have appropriate goals established, in either case, the goals or performance criteria are to be commensurate with safety.
Provided that an SSC meets its performance criteria or does not experience a repetitive maintenance preventable functional failure (MPFF),5 the preventive maintenance for that SSC is considered to be effective, and monitoring can continue under Paragraph (a)(2).
When the SSC does not meet a performance criterion or experiences a repetitive MPFF, the licensee must determine whether the SSC should be monitored under Paragraph (a)(1). In addition to monitoring reliability and/or availability, as appropriate, SSCs monitored under Paragraph (a)(1) are expected to have goals that specifically address the cause of the problem that resulted in the SSC being monitored in accordance with Paragraph (a)(1).
Licensees are expected to monitor the performance or condition of SSCs within the scope of the rule against the goals and performance criteria on an ongoing basis. As required by Paragraph (a)(3), licensees must assess the effectiveness of maintenance at least once per refueling cycle not to exceed 24 months between evaluations.
'NUMARC 93-01 uses goals and performance criteria with a specific meaning. Goals are used for SSCs monitored under Paragraph (a)(1), while performance criteria are used for SSCs monitored under Paragraph (a)(2).
The MPFF is a construct of NUMARC 93-01, defined as a failure that results in a loss of the function that caused the SSC to be within the scope of the rule (e.g., the failure resulted in a scram) and could have been prevented through more effective maintenance prior to the failure.
i Transition from Prescriotive to Performance-Based Reaulation When the maintenance rule was issued, it was described as a results-oriented, performance-based rule, but it does have prescriptive aspects as well. Specifically, the maintenance rule includes the SSC scoping criteria and the requirement to periodically evaluate mairstenance 4
effectiveness. In the context of the maintenance rule, performance-based referred to two aspects of how the rule is implemented by licensees, and to how the NRC staff would inspect j
and enforce the rule.
I From an implementation standpoint, the maintenance rule is performance-based because it
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gives licensees flexibility and because the reaulatory reauirements vary with SSC performance, as follows 4
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Flexibility: The rule gives licensees the flexibility to: 1) establish the performance and I
condition goals, and the requisite equipment monitoring regimes; 2) modify established goals on the basis of plant or equipment performance; and 3) determine whether to rely on preventive maintenance in lieu of establishing goals and performance or condition monitoring. The rule prescribes no specific methodology to l
accomplish these activities; it only requires that licensees establish goals that are commensurate with safety.
Reaulatory Reauirements Vary With SSC Performance: The rule also allows l
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, licensees to forego the monitoring requirements of Paragraph (a)(1) if the licensee
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i can demonstrate that the preventive maintenance for an SSC is effective. Therefore, licensees that establish effective preventive maintenance programs can reduce the 4
I monitoring activities imposed by the rule. An effective preventive maintenance program can generally be defined as a program that reduces failures to an acceptable j
level while achieving the appropriate reliability and availability.
i From an inspection and enforcement standpoint, the maintenance rule also has both
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prescriptive (or programmatic) and performance-based elements. The baseline inspection l
program is a programmatic inspection of licensees' activities to comply with the rule. In 1994 l
the NRC staff determined that it would be necessary to perform baseline inspections because the NRC staff could not rely solely on performance-based inspections until the NRC staff developed confidence that the programs licensees developed to implement and comply with the rule would accurately monitor maintenance performance, and that licensees would adjust their maintenance activities and programs where performance indicated changes were i
necessary.
i in the long term, the NRC staff expects to focus on the results of the licensee's maintenance
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activities using IP 62707, " Maintenance Observation." inspections conducted in accordance with IP 62707 address, in part, whether maintenance was effective in preventing failures, and j
where problems occur, the effectiveness of the licensee's corrective actions. Unless performance indicates that a potential programmatic problem may exist, the NRC staff does j
not expect to be involved in the licensee's programs to accomplish and monitor maintenance i
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(e.g., procedures, training). Therefore, the regulatory burden is expected to be lower for those licensees that have effective maintenance programs.
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Risk-Informed Aspects of the Maintenance Rule i
At the time the maintenance rule was issued it was considered a performance-based rule; the concept of " risk-informed" was not in general use. While the rule required that licensees l
establish goals commensurate with safety, the intention of the NRC at that time was not as mature as the current concept of risk-informed thinking. However, in the statements of l
consideration for the maintenance rule,' the NRC clearly encouraged licensees to use assumptions and results associated with probabilistic risk assessments (PRAs) and Individual Plant Evaluations (IPEs) when establishing the goals required by Paragraph (a)(1). The NRC' C
also clearly expected licensees to consider risk when performing the Paragraph (a)(3) assessments of the impact on safety when removing equipment from service. While the use of PRA was not explicitly required, the NRC stated that the Paragraph (a)(3) assessments were expected to be refined on the basis of technologicalimprovement and experience. As previously stated, this provision of Paragraph (a)(3) is not a requirement.
l Furthermore, the endorsed method of implementing the maintenance rule in'NUMARC 93-01
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describes an approach that relies on the assumptions and results of the licensee's risk analyses.7 When implementing the rule using this approach, licensees consider their risk analyses when categorizing the SSCs that are within the scope of the rule as having high or low safpty significance, and when establishing performance criteria and goals for SSCs of high safety significance.- Licensees are also encouraged to use risk analyses for the j
Paragraph (a)(3) safety assessments when removing equipment from service for preventive j
maintenance.
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Therefore, although the maintenance rule was not initially described as a risk-informed rule, the industry's implementation of the rule has evolved to include some aspects that would be considered part of risk-informed regulation. Unlike other potential risk-informed applications
'(e.g., graded quality assurance, inservice testing) the general issues that have been raised regarding risk-informed regulation, such as quality of PRAs, pose less of a problem for the maintenance rule because the maintenance rule adds, rather than relaxes, regulatory requirements, the SSCs within the scope of the rule are established through deterministic means (PRAs provide only one input, and cannot be used to exclude an SSC from the scope of the rule), and the maintenance rule includes a feedback mechanism that is self-correcting
' if safety significance ranking errors are made due to poor quality PRAs. The use of PRA in
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the maintenance rule was described in SECY 95-265, " Response to August 9,1995, Staff 1
' Licensees that implement the maintenance rule using NUMARC 93-01 are not required to take the PRA attemative described in that document. However, the PRA attemative is the only method described in detail in NUMARC 93-01, and all licensees that participated in the pilot program and have had baseline inspections used the PRA approach.
1 l* i Requirements Memorandum Request to Analyze the Generic Applicability of the Risk 3
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Determination Process Used in implementing the Maintenance Rule," dated November 1, 1995.
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DISCUSSION:
From the effective date of the maintenance rule through February 14,1997, the NRC staff I
_ completed 18 maintenance rule baseline inspections using IP 62706,' and completed i
Revision 2 to RG 1.160. The NRC staff has a number of additional activities to complete related to the maintenance rule, i
Maintenance Rule Baseline Inspections Findinas
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Each maintenance rule inspection is site-specific. Although all the licensees inspected to i
date have implemented the rule using RG 1.160 and NUMARC 93-01, each licensee has developed a unique site-specific program. This presents a challenge to the inspectors in that
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they must fully understand each licensee's approach, and determine whether the licensee's program meets the requirements of the maintenance rule. For example, plants of si'milar design may have different: numbers of SSCs, numbers of SSCs in scope of the rule, number i
of SSCs of high safety significance, numbers of SSCs monitored in accordance with l
Paragraph (a)(1) versus (a)(2), and values of performance criteria and goals. The inspectors must evaluate each licensee's approach on its merits, as the specific values for each of the above, factors is affected by tne licensee's implementation method. This variation was j
expected, however, and is consistent with the NRC's intention to give licensees maximum flexibility in implementing the rule.
The NRC staff has been able to accomplish the inspections by dedicating sufficient resources to the inspection effort; providing extensive training for inspectors regarding the requirements of the maintenance rule and the guidance in RG 1.160, NUMARC 93-01, IP 62706 and IP 62707; and ensuring effective communication between the regions and the Office of Nuclear Reactor Regulation (NRR). The following paragraphs summarize the findings from -
l the initial baseline inspections.
l In general, the NRC staff finds that licensees have adequately implemented the requirements of the maintenance rule. However, in a few cases, despite the five year implementation period, the inspections identified that some licensees waited until the year prior to the effective date of the rule to aggressively pursue implementation. For those licensees, the j
baseline inspections identified weak programs and/or weak implementation of those j
j programs.
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'The NRC staff has also completed three other non-baseline maintenance rule j
inspections. The results of those inspections are consistent with those identified during
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l baseline inspections.
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Even where licensees allowed adequate time to implement the maintenance rule, the baseline inspections identified two issues at most sites. First, many licensees have failed to 4
i demonstrate that the goals and performance criteria were established commensurate with safety. For example, the licensees allowed each SSC a standard number of MPFFs per i
cycle as a reliability performance criterion, without consideration of the number of demands on the SSC. In some cases, when compared to the number of demands, the number of i
MPFFs allowed would be indicative of much lower reliability than the licensee assumed in its risk analyses. The NRC staff position has been that licensees must demonstrate a sound i
technical basis for the values of the performance criteria and goals.' The second common i
finding has been that many licensees did not develop both reliability and unavailability j
^ performance criteria or goals for SSCs of high safety significance. As part of the periodic evaluations required by Paragraph (a)(3), licensees are required to balance reliability and unavailability; this balance cannot be attained unless the licensee monitors both of these l
parameters.
The inspections have also identified scoping issues at several sites. While some examples were observed where safety-related SSCs were not included within the scope of the rule, in most cases findings related to scoping were limited to nonsafety-related SSCs and were relatively minor. For example: 1) a failure to include the cooling tower system in the scope even though the system's failure had resulted in a scram on one occasion and a near scram on another; and 2) failure to include communications and/or emergency lighting systems in i
scope even though industry operating experience has demonstrated their importance in mitigating accidents and transients and completing the activities required by emergency operating procedures.
5 The staff has observed that some licensees appear reluctant to identify failures as MPFFs.
l From a regulatory standpoint, the occurrence of an MPFF is not a violationc Rather, an MPFF Indicates a potential problem; what is most important is that the licensee take effective corrective actions. This reluctance to identify MPFFs has resulted in some violations for j
failure to monitor the performance of SSCs within the scope of the rule.
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The need for additional guidance regarding structural monitoring was identified before the effective date of the rule. Revision 2 to NUMARC 93-01 contains some additional guidance, l
however, the industry was expected to finalize the comprehensive guidance developed in NEl 96-03, " Guideline for Monitoring the Condition of Structures at Nuclear Power Plants."
This document is intended to provide structural monitoring guidance for all regulatory 1
applications and not just the maintenance rule. The NRC staff has provided comments to NEl on NEl 96-03, but NEl has not yet finalized NEl 96-03 to address the staff's comments.
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^Therefore, the NRC staff has been unable to endorse NEl 96-03. The result of the unavailability of guidance on monitoring the condition of structures is that, in all but three inspections (which were found acceptable), the inspectors did not assess or were unable to 4
conclude whether the licensee's program for monitoring structures complied with the rule.
I For these 15 sites the inspections identified structural monitoring as an inspection followup item, to be reevaluated after the structural monitoring guidance became available. Since i
NEl 96-03 has not yet been endorsed, the NRC staff has provided maintenance rule-specific structural monitoring guidance in RG 1.160, Revision 2.
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I Finally, licensees have, in general, adequately performed safety assessments when removing j
equipment from service for maintenance in accordance with Paragraph (a)(3) of the rule.
However, some inspections have identified isolated cases of weak safety assessments for removing equipment from service for maintenance. Because this provision of the rule is not i
an explicit requirement in that the rule states that licenses "should" perform the safety assessments, the NRC staff has been unable to enforce this provision (although in most cases the licensees have accepted the NRC staffs comments and corrected their programs).
Maintenance Rule Baseline Inspection Enforcement Of the 11 baseline inspections for which enforcement action is complete, nine of them have resulted in proposed enforcement actions (two inspections identified no violations). One inspection resulted in escalated enforcement, which resulted in one Severity Level ill violation but no civil penalty. Eight inspections resulted in one or multiple Severity Level IV violations.
For the remaining inspections the enforcement actions are under evaluation by the NRC staff.
i Licensee Reactions to the Baseline inspections Most licensees have indicated that they believe the NRC staff is being consistent in the inspection and enforcement of the maintenance rule.
NEl and some licensees have asserted that the violations cited for inadequate reliability perfonpance criteria or goals represent a new staff position and, consequently, the staff i
should not take enforcement action on this " generic" concem until additional guidance is j
issued. However, the NRC staff did not agree with this assertion, and in a letter to NEl dated j
October 22,1996, reiterated the NRC staffs position that the need for a sound technical j
basis for reliability performance criteria is not a new staff position and that the guidance available is adequate. Nonetheless, the staff has added a clarification in RG 1.160, Revision 2, to eliminate any confusion regarding this issue.
NEl and some licensees expressed some concem that the baseline inspections are programmatic and not performance-based. The NRC staff agrees that the baseline l
inspections are more programmatic than performance-based. The NRC staff recognized i
early in the implementation period that it could not rely solely on performance-based inspection of the maintenance rule until the NRC staff had confidence that the programs licensees developed and implemented to comply with the rule would accurately monitor maintenance performance, and that licensees would adjust their maintenance programs where performance indicated changes were necessary.
in the long-term, the NRC staff expects that maintenance rule inspections will become more J.
performance-based and less programmatic. After completing the baseline inspection l
program, the maintenance rule will primarily be inspected using IP 62707, which is i
performance-based with regard to the maintenance rule aspects and has been used by j
resident inspectors for their maintenance inspections since the effective date of the 1
maintenance rule. The NRC staff will primarily use IP 62706 when licenue performance i
indicates that potential programmatic problems exist.
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Industry expressed a concern prior to the effective date of the maintenance rule that the NRC staff would use the broad wording of the scoping criteria in Paragraph (b) of the rule to eventually include all SSCs within scope. NEl restated this concem in a public meeting on January 9,1997. However, the only examples of inappropriate SSCs added to scope that NEl provided during the meeting were the communications and emergency lighting systems.
As previously discussed, the NRC staff believes that industry operating experience has 3
demonstrated that these systems are necessary to mitigate accidents and transients and to complete the activities in the EOPs, and provide a significant fraction of the mitigating function. Therefore, the NRC staff has generally concluded that these systems should be within the scope of the rule.
i Revision 2 to RG 1.160 During the implementation period of the maintenance rule it became apparent that the i
guidance documents would require revision to reflect lessons leamed. The need for an
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iterative process arises from the general requirements of the rule and the flexibility given licensees to implement them; that is, until full implementation can be observed, it is difficult to j
determine if the guidance has sufficient details to ensure compliance with requirements.
l As previously described, the industry conducted a V&V program and the NRC staff conducted j
a pilot program to assess, in part, the adequacy of the inspection procedures and i
implementation guidance documents. Following those programs, NEl issued Revision 2 to NUMA8C 93-01 (April 1996). The NRC staff then issued DG-1051 (the proposed RG 1.160, i
Revision 2) in August 1996, with a public comment period that ended on November 15,1996.
However, the NRC staff did not complete RG 1,160, Revision 2, until February 1997 because l
of the desire to incorporate lessons leamed from the initial baseline inspections.
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Revision 2 to RG 1.160 endorses and clarifies the guidance provided in NUMARC 93-01,-
Revision 2. It also incorporates clarifications that resulted from public comments regarding l
DG-1051, experience with the baseline inspections, and two public meetings held on l
October 15,1996, and January 9,1997. The following paragraphs discuss the most j
significant clarifications incorporated in Revision 2 to RG 1.160:
i Chanaes to the Rule: The maintenance rule has been amended twice since i
RG 1.160, Revision 1 was issued.' As noted previously, on August 28,1996, the rule was amended to specifically address the SSCs within the scope of the ru!e for decommissioned plants. On December 11,1996, as part of the final rule-making for
" Reactor Site Criteria including Seismic and Earthquake Engineering Criteria for Nuclear Power Plants," the NRC changed the definition of safety related SSCs in l
Paragraph (b)(1) of the maintenance rule to make it consistent with its use in other l
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' Revision 1 to the regulatory guide was issued in January 1995 to reflect an earlier rule i
change that extended the period of the Paragraph (a)(3) periodic assessments from at least j
once every 12 months to at least once per refueling cycle not to exceed 24 months between evaluations.
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regulations. Neither of these rule changes is expected to impact operating reactor licensees.
i' Safety Sionificance'Cateaorization Process: This clarification notes that the NRC staff's endorsement of the safety significance categorization process described in NUMARC 93-01, Revision 2, is limited to the maintenance rule. It also notes that i
l RG 1.160 is expected to be revised in the future, if needed, to reflect the proposed
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regulatory guide on the use of PRA in regulatory matters. Such a revision to RG 1,160 is desirable for reasons of regulatory consistency, and is also consistent with the NRC's intent (as presented in the statements of consideration for the 3
maintenance rule) that licensees' approaches to the rule could change as a result of technological improvements and experience. Licensees will be encouraged to use 4
i this guidance when it is available.
I Scooina: Despite the fact that the scoping-related requirements defined in Paragraph (b) are prescriptive, experience indicated the need for four clarifications, of j
which the following two are significant:
L Could Cause: This clarification provides guidance on how to identify the i
nonsafety-related SSCs that should be included within scope because their failure could cause a reactor scram or safety system actuation.
SSCs Relied Upon to Mitiaate Accidents or Transients or Used in EOPs: This l
modification clarifies that this scoping criterion includes those SSCs that are used to directly address the accident or transient or are explicitly used in the EOPs, l
and provide a significant fraction of the mitigating function. In addition, this j
scoping criterion includes within scope those SSCs whose use is necessary to mitigate accidents or transients or to use the EOPs (even though the SSCs do i
not directly address the accidents or transients or may not be explicitly used in l
EOPs) and provide a significant fraction of the mitigating function (the NRC staff added this clarification after a number of licensees excluded communications and emergency lighting systems, as was previously discussed).
i MPFFs as a Reliability Indicator. As previously discussed, the staff has cited i
numerous licensees for failure to establish reliability performance criteria that are i
commensurate with safety because the licensees did not have a sound technical basis j
for the values of the performance criteria. Revision 2 to the RG clarifies how MPFFs can be used as an indicator of reliability.
i Structural Monitorina: During the pilot program, it became apparent that there was a need to improve the guidance in NUMARC 93-01 for structural monitoring (some i
additional guidance was provided in Revision 2). As previously noted, most inspections identified structural monitoring as an inspection followup item until j
additional guidance became available. The industry is developing comprehensive j
guidance in NEl 96-03, but the staff determined that it was important to provide f
1
h i,
additional guidance to licensees qu'ickly. Therefore, the NRC staff added guidance in RG 1.160, Revision 2.
Normally Operatina SSCs of Low Safety Sianificance: As previously noted, normally
=
operating SSCs of low safety significance are generally monitored at the plant level.
Experience during the pilot program and baseline inspections indicated the need for j
additional clarification in this area. RG 1.160, Revision 2, provides three clarifications i
regarding the treatment of normally operating SSCs of low safety significance; one of these clarifications is significant. Specifically, during the pilot site visits and baseline inspections, the NRC staff noted that some licensees were only monitoring the j.
number of unplanned automatic scrams, and were not monitoring unplanned manual 1
scrams even when the manual scram was initiated in anticipation of an automatic scram. Given that one of the principal reasons for developing a maintenance rule was n
the number of reactor scrams (both manual and automatic) caused by failures in the balance of plant, the NRC staff position has been that licensees should monitor all unplanned scrams in order to assess the effectiveness of their preventive maintenance for those SSCs monitored at the plant level.
l
)
Additional NRC Staff Activities Related to the Maintenance Rule l
The remaining NRC staff activities related to the mai.;tanance rule are as follows:
i
, Complete Baseline Inspections: The NRC staff's goal has been to complete a j
baseline inspection of every licensee's maintenance rule program by July 10,1998.
The regional offices are committed to achieving this goal.
d i
i issue an Information Notice: As part of its efforts to maintain effective communication
=
i.
with the industry and public regarding the maintenance rule, the NRC staff is developing an information notice to communicate the results and lessons teamed from the initial baseline inspections thus far.
Revise IP 62706: The base!ine inspection procedure needs to be revised to reflect the changes to Revision 2 to RG 1.160 and NUMARC 93-01.
Update and Make Maintenance Rule Home Paae Publiciv Accessible: As part of its efforts to maintain effective communication with the industry and the public regarding the maintenance rule, the NRC staff has developed a prototype "home page" for the world wide web. Once the home page is updated with the most recent information and prototype testing is completed, the NRC staff will make the home page publicly accessible; The intent of the home page is to provide a comprehensive resource of maintenance rule-related regulatory documents, guidance documents, inspection procedures, and inspection reports in a searchable format.
Revise the Enforcement Guidance: The NRC staff has used an enforcement guidance memorandum (EGM-96-002) to determine the appropriate enforcement-l
i 14 4
i i
action for maintenance rule inspection findings. This EGM needs to be revised to reflect lessons leamed.
Develoo Continuina Trainina Proaram: To date, maintenance rule training has been provided by the Quality Assurance and Maintenance Branch (HQMB) in NRR, which e
j has programmatic responsibility for the rule. In the future, however, the responsibility i
for training the NRC staff on the maintenance rule will be transferred to the Technical Training Division ('ITD) of the Office for Analysis and Evaluation of Operational Data.
i The TTD has participated in the training program's development and is preparing to 8
assume this responsibility.
LESSONS LEARNED:
The implementation and initial baseline inspections have provided the NRC staff with a number of lessons leamed regarding what was effective and what could be improved. These lessons leamed can be grouped into four categories: importance of communication, value of the pilot program, importance of training, and inspection and enforcement; as described in the following sections.
Importance of Communication The development and implementation of the maintenance rule has involved extensive commynication and interaction within the NRC staff (headquarters and the regional offices) and between the NRC staff and the industry and public. These interactions : included numerous public meetings, industry workshops, and active solicitation of industry and public comments on proposed guidance documents and inspection procedures.
Communication between the industry and the NRC staff has been enhanced by keeping a core NRC staff stable and accessible during the implementation period. This improved 1
communication because the NRC staff became well known to industry representatives.
The NRC staff also maintained extensive communication among the affected intemal organizations. For example, the inspection procedures and enforcement guidance were developed by headquarters with regional office input. The training program provided to all maintenance rule inspectors improved communication through personal contact and development of a sense of community as a result of the shared experience of the training. A maintenance rule-specific enforcement panel was created to address enforcement actions; members of the panelinclude representatives from NRR, the Office of Enforcement (OE),
and the appropriate regional office, in addition, representatives of the NRC staff held an i
intemal workshop in December 1996; participants included NRR and all four regional offices.
The working relationships developed through these activities aided the consistency of inspection and enforcement across the regions, which directly addressed the industry's concem that the NRC would be inconsistent when inspecting and enforcing the maintenance rule.
i I
- 4.
I
' As previously noted, the NRC staff plans to continue to maintain open communication by l
~ issuing an information notice, revising IP 62706, developing a continuing training program, j-and providing public access to maintenance rule information over the intemet.
==
Conclusion:==
The maintenance rule provides a good example of the importance of communication among the NRC staff and between the NRC staff and f
the industry and public in the effective implementation, inspection and enforcement of a performance-based rule.
Value of the Pilot Proaram
(
Early in the implementation period the NRC staff decided that a pilot program would yield i
substantial benefit with regard to the utility of the implementing guidance and inspection procedure for the maintenance rule. The pilot program provided an early test application of the guidance and IP from which a great deal was learned by both industry and the NRC staff.
.l As an added benefit, these findings were not encumbered by enforcement actions since the rule had not yet gone'into effect. The pilot program, lessons teamed document (NUREG-1526), and public workshop of the results of the pilot program were completed more than one year before the effective date of the rule. This should have given licensees ample time to refine the implementation of their maintenance rule programs on the basis of the lessons-leamed.
Conclu,sion:
The NRC staff's pilot program improved the implementation guidance and inspection procedure, and helped licensees and the NRC staff reach an understanding regarding what constitutes acceptable maintenance monitoring required by the rule.
Imoortance of Trainina As a new major regulatory initiative, the maintenance rule was made more complex both for licensees to implement and for the NRC staff to inspect and enforce because it involved a performance-based regulatory approach. This approach did not clearly define what was
" acceptable," and the NRC staff had little experience with inspection and enforcement of such a rule. This required extensive training of the NRC staff assigned to participate in oversight of the maintenance rule.
As a result, HQMB developed a three-tier training program. The first tier comprised an
' overview course (one to two hours) developed for managers and those NRC staff who would only be marginally involved with the maintenance rule (e.g., most headquarters staff and management). The second tier comprised a one day course for NRC staff who would be directly involved in oversight of the maintenance rule, although they might not participate in the baseline inspection program (e.g., resident inspectors, some headquarters staff, and regional management). The third tier comprised a three day course for the NRC staff who would participate in or lead the maintenance rule baseline inspections (e.g., regional inspectors, some resident inspectors, and some headquarters staff). HQMB has given 36 training sessions. Over eight hundred members of the NRC staff have received at least one
l 1
4 i
=
i l
of these training courses as follows: 134 received the three day course; 376 received the one i-day course; and 412 received the overview course.
==
Conclusion:==
The inspection and enforcement of the maintenance rule has benefited from the training program.
Inspection and Enforcement The initial bas'eline inspections have demonstrated that inspection of the maintenance rule is
~
challenging, but that the rule can be inspected and enforced in a consistent manner. It is also apparent that inspection and enforcement has been complicated because the maintenance rule includes one provision that is not a requirement.
A maintenance rule baseline inspection is challenging primarily because of the flexibility that the rule gives licensees. This flexibility results in a unique site-specific implementation of the rule at each site. The inspections therefore require additional resources so that each licensee's program can be fully understood and evaluated.
l Although the maintenance rule does not explicitly require the use of PRA, all licensees 1
inspected to date have used PRA methods. This required the inspection team to include an j
inspector with considerable PRA expertise (to date this expertise has primarily come from the i
senior reactor analysts and significant contractor support). The net result is that, at a minimym, a maintenance rule inspection team consists of a team leader, four inspectors (one of which has PRA expertise), and a staff support member from HQMB whose primary role is to promote consistent inspection and provide guidance on staff positions (the staff support l
member also frequently fulfills an inspector role). The inspections consist of a week for j
preparation, a week of onsite inspection, and a week for documentation.
l l
l Despite the site specific approach of each licensee's implementation of the maintenance rule, j
the NRC staff believes that the maintenance rule is being inspected and enforced in a consistent manner across the regions. In general, the NRC staff has achieved consistency 4
through the training program, joint participation by all four regions in the first baseline inspection, HQMB participation in all baseline inspections, and the maintenance ruie-specific enforcement panel.
Another challenge in inspecting and enforcing the maintenance rule is that the rule includes a provision that is not a requirement. Specifically, Paragraph (a)(3) states that licensees "should" assess the impact on safety when removing plant equipment from service for preventive maintenance. In general, licensees have voluntarily complied because it is obvious that there is a nexus between safety and equipment out of service; had there not been such a clear relationship to safety, fewer licensees may have elected to implement a provision that is not a requirement. However, in the few cases where the NRC staff has observed either weak implementation or plant configurations for which the licensee did not adequately assess the configuration's safety impact, the staff was unable to enforce this provision of the rule. Under the current enforcement guidance, the NRC staff cannot enforce
. this part of Paragraph (a)(3) unless the failure to perform an adequate assessment causes an j
1
' 4 event or contributes to the severity of or complicates recovery from an event. Even then, enforcement is limited to using the inadequate safety assessment as an escalating factor on other enforcement actions that are taken as a result of the event.
One way to resolve the enforcement problem created by the safety assessment prowiolon c' Paragraph (a)(3) would be a rule-making to change the "should" in Paragraph (a)(3) to "shall," which would make this part of the rule a requirement. However, the NRC staff does not believe that a rule change is necessary at this time because the NRC staff has only identified isolated instances of weak safety assessments to date and licensees are in effect treating this provision as a requirement. If the NRC staff finds more cases of weak safety assessments during other maintenance rule inspections, the NRC staff may recommend that the rule be changed.
s
==
Conclusions:==
- 1. The NRC staff can consistently inspect and enforce a risk-informed, performance-based rule such as the maintenance mle.
\\
- 2. Because the provision in Paragraph (a)(3) that states that licensees "should" assess the impact on safety when removing equipment from service is not a requirement, this provision is unenforceable. At this 1
time the NRC staff does not believe a rule change is necessary because licensees are in effect treating this provision as a requirement. However, the NRC staff may recommend a rule change if other maintenance rule inspections identify additional cases of weak safety assessments.
INSIGHTS FOR OTHER RISK-INFORMED. PERFORMANCE-BASED REGULATIONS:
As a result of the initial bassline inspections of the maintenance rule, the NRC staff has identified the following insights for consideration in the development of other risk-informed, performance-based rules:
Because of the flexibility given to licensees by performance-based rules, effective communication among the NRC staff and between NRC staff, industry and the public is essential to the successful implementation, inspection and enforcement of these rules.
Consideration should be given to conducting a pilot program to test implementation and inspection of these rules.
~
The NRC staff and licensees should anticipate several iterations of the implementation
=
guidance and inspection procedures in order to benefit from lessons learned through the pilot program and initial inspections.
l A programmatic baseline inspection program may be necessary to provide confidence that the licensees have programs that effectively monitor performance, and that j
licensees adjust their activities and programs where performance indicates changes are necessary. The NRC staff should not take a performance-based approach to inspection unless such confidence has been obtained, j
NRC resource requirements for these rules are high, and should be acknowledged i
and committed to up front. Effective communication, development of guidance documents and inspection procedures,, training, program oversight, and baseline inspections probably require more resources for performance-based rules than for prescriptive regulations in general.
.The rules must be written in a manner to only contain requirements. Other types of l
language in the rules, such as hortatory provisions, are unenforceable. Where practical, the rules should define the minimum performance standards (this was not j
. practical in the case of the maintenance rule).
1 CONCLUSIONS:
On the basis of the NRC staff's findings to date, the implementation, inspection, and enforcement of the maintenance rule have been successful. Concems have been identified, but overall, licensees irispected to date have adequately implemented the rule. The NRC staff hgs completed the activities that needed to be completed, and a schedule for the remainder of the activities related to the rule has been established. Moreover, the lessons :
leamed from the implementation, inspection and enforcement of the maintenance rule should benefit other risk-informed, performance-based regulations.
1 L Joq ph Callan, Executive Director for Operations 1
Attachment:
RG 1.160, Revision 2 DISTRIBUTION:-
Commissioners OGC OCAA OIG OPA OCA ACRS EDO REGIONS SECY 6
Revision 2 March 1997 Regulatory Guide 1.160 (Draft was DG-1051)
MONITORING THE EFFECTIVENESS OF MAINTENANCE AT NUCLEAR POWER PLANTS i
A. INTRODUCTION The NRC published the maintenance rule on July 10, 1991, as Section 50.65, " Requirements for Monitoring the Effectiveness of Maintenance at j
Nuclear Power Plants," of 10 CFR Part 50, " Domestic Licensing of Production and Utilization Facilities." The NRC's determinatic., that a maintenance rule was needed arose from the conclusion that proper mhb.tenance is essential to plant safety. As discussed in the regulatory analysis for this rule,* there is a clear link between effective maintenance and safety as it relates to such factors as the number of transients and challenges to safety systems and the 1
associated need for operability, availability, and reliability of safety equip' ment.
In addition, good maintenance is also important in providing assurance that failures of other than safety-related structures, systems, and components (SSCs) that could initiate or adversely affect a transient or j
accident are minimized.
Minimizing challenges to safety systems is consistent with the NRC's defense-in-depth philosophy. Maintenance is also important to ensure that design assumptions and margins in the original design basis are l
maintained and are not unacceptably degraded.
Therefore, nuclear power plant maintenance is clearly important in protecting public health and safety.
Paragraph (a)(1) of 10 CFR 50.65 requires that power reactor licensees monitor the performance or condition of SSCs against licensee-established goals in a manner sufficient to provide reasonable assurance that such SSCs i
are capable of fulfilling their intended functions.
Such goals are to be
'NRC Memorandum to All Commissioners from J. Taylor on " Maintenance Rulemak-ing," June 27, 1991.
Copies are available for inspection or copying for a fee from the NRC Public Document Room at 2120 L Street, NW., Washington, DC; the PDR's mailing address is Mail Stop LL-6, Washington, DC 20555; phone (202)634-3273; fax (202)634-3343.
1 Attachment
+
established commensurate with safety and, where practical, take into account industry-wide operating experience. When the performance or condition of an SSC does not meet established goals, appropriate corrective action must be taken.
For a nuclear power plant for which the licensee has submitted the certifications specified in 10 CFR 50.82(a)(1) (i.e., plants undergoing decommissioning), Paragraph (a)(1) of 10 CFR 50.65 applies only to the extent 2
that the licensee must monitor the performance or condition of all SSCs i
associated with storing, controlling, and maintaining spent fuel in a safe condition, in a manner sufficient to provide reasonable assurance that such SSCs are capable of fulfilling their intended functions.*
4 Paragraph (a)(2) of 10 CFR 50.65 states that monitoring as specified in Paragraph (a)(1) is not required where it has been demonstrated that the performance or condition of an SSC is being effectively controlled through the I
performance of appropriate preventive maintenance, such that the SSC remains capable of performing its intended function.
Paragraph (a)(3) of 10 CFR 50.65 requires that performance and condition monitoring activities and associated goals and preventive maintenance activities be evaluated at least every refueling cycle provided the interval between evaluations does not exceed 24 months.
The evaluations must be i
conducted taking into account, where practical, industry-wide operating experience.
Adjustments must be made where necessary to ensure that the i
objective of preventing' failures of SSCs through maintenance is appropriately balanced against the objective of-minimizing unavailability of SSCs because of monitoring or preventive maintenance.
In performing monitoring and preventive
)
maintenance activities, an assessment of the total plant equipment that-is out of service should be taken into account to determine the overall effect on performance of safety functions.
Paragraph (b) of 10 CFR 50.65 states that the scope of the monitoring i
- program specified in Paragraph (a)(1) is to include safety-related and nonsafety-related SSCs as follows.
4 (1)
Safety-related structures, systems, or components that are relied upon to remain functional during and following design basis events to ensure the integrity of the reactor coolant pressure boundary, i
The specific requirements for decommissioning plants became effective August 28, 1996.- See 61 FR 39278, July 19, 1996, " Decommissioning of Nuclear Power Reactors."
2 3
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the capability to shut down the reactor and maintain it in a safe shutdown condition, and the capability to prevent or mitigate the consequences of accidents that could result in potential offsite exposure' comparable to the guidelines in' 10 CFR 50.34(a)(1) or 6 100.11 of this chapter, as applicable.'
(2)
Nonsafety-related structures, systems, or components:
(i)
That_are relied upon to mitigate accidents or transients or are used in plant emergency operating procedures (E0Ps); or (ii) Whose. failure could prevent safety-related structures, systems, and components from fulfilling their safety-related function; or (iii) Whose failure could cause a reactor scram or actuation of a safety-related system.
Paragraph (c) of 10 CFR 50.65 states that the rule provisions are to be implemented by licensees no later than July 10, 1996.
This Regulatory Guide 1.160 is being revised to endorse Revision 2 of-NUMARC 93-01, " Industry Guideline for Monitoring the Effectiveness of' Maintenance at Nuclear Power Plants"' (April 1996), which has been updated by the Nuclear Energy Institute.
The regulatory guidance is intended to provide flexibility for a licensee to structure its maintenance program in accordance with the safety significance of those SSCs within the scope of the rule.
The information collections contained in this regulatory guide are covered by the requirements of 10 CFR Part 50, which were approved by the
. Office of Management and Budget, approval number 3150-0011.
The NRC my not conduct or sponsor, and a person is not required to respond to, a c-lection Lof information unless it displays a currently valid OMB control ni ser.
'This Paragraph (b)(1) of the maintenance rule was changed in the final rulemaking for " Reactor Site Criteria Including Seismic and Earthquake Engineering Criteria for Nuclear Power. Plants," December 11, 1996.
See 61 FR 65157.
This document is available for inspection or copying for a fee in the NRC
.Public Document Room, 2120 L Street NW., Washington, DC; the PDR's mailing address is Mail Stop LL-6, Washington, DC 20555; phone (202)634-3273; fax (202)634-3343.
3
B. DISCUSSION OBJECTIVE l
d
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i The objective of 10 CFR 50.65 (referred to hereafter as the maintenance j
rule or the rule) is to require monitoring of the overall continuing effectiveness of liunsee maintenance programs to ensure that (1) safety-related and certain nonsafety-related SSCs are capable of performing their intended functions and (2) for nonsafety-rela,ted equipment, failures will not occur that prevent the fulfillment of safety-related functions, and failures resulting in scrams and unnecessary actuations of safety-related systems are minimized.
DEVELOPMENT OF INDUSTRY GUIDELINE. NUMARC 93-01 The nuclear industry developed a document, NUMARC 93-01, " Industry Guideline for Monitoring the Effectiveness of Maintenance at Nuclear Power
)
Plants" (May 1993),3 that provides guidance to licensees regarding implementation of the maintenance rule. This document was prepared by NUMARC.
A verification and validation (V&V) effort was conducted by NUMARC, with NRC staff observation, to test the guidance document on several representative systems. A number of changes were made to the NUMARC guidance document based on the results of the V&V effort.
The NRC staff reviewed this document and found that it provided acceptable guidance to licensees.
In June 1993, the NRC staff issued Regulatory Guide 1.160, " Monitoring the Effectiveness of Maintenance at Nuclear Power Plants," which endorsed the May 1993 version of NUMARC 93-01.
In January 1995, the NRC staff issued Revision 1 to Regulatory Guide 1.160 to reflect the amendment to 10 CFR 50.65(a)(3) that changed the requirement for performing the periodic evaluation from annually to once per refueling cycle, not to exceed 24 months between evaluations.
i From September 1994 to March 1995, the NRC staff performed a series of i
nine pilot site visits to verify the usability and adequacy of the draft NRC maintenance rule inspection procedure and to determine the strengths and weaknesses of the implementation of the rule at each site that.used the guidance provided in NUMARC 93-01.
The findings are described in NUREG-1526,
" Lessons Learned from Early Implementation of the Maintenance Rule at Nine 4
Nuclear Power Plants,"' (June 1995).
The NRC staff concluded that the requirements of the rule could be met more consistently across the industry if some clarifying guidance was added to NUMARC 93-01 to address the findings noted in NUREG-1526. The NRC staff met with industry representatives in a series of public meetings to discuss proposed revisions to NUMARC 93-01 that would address the findings noted during the site visits.
Revision 2 to NUMARC 93-01 (April 1996) resulted from these meetings.
ELANT. SYSTEM. TRAIN. AND COMPONENT MONITORING LEVELS The extent of monitoring may vary from system to system. depending on the system's importance to safety.
Some monitoring at the component level may be necessary; however, it is envisioned that most of the monitoring could be done at the plant, system, or train level.
SSCs with high safety significance and standby SSCs with low safety significance should be monitored at the system or train level.
Except as noted in the Regulatory Position of this guide, normally operating SSCs with low safety significance may be monitored through plant-level performance criteria, including unplanned automatic scrams, safety system actuations, or unplanned capability loss factors.
For SSCs monitored in accordance with 10 CFR 50.65(a)(1), additional parameter trending may be neces'sary to ensure that the problem that caused the SSC to be placed in the Paragraph (a)(1) category is being corrected.
.USE OF EXISTING LICENSEE PROGRAMS The NRC staff encourages licensees to use, to the maximum extent practicable, activities currently being conducted, such as technical specification surveillance testing, to satisfy monitoring requirements.
Such activities could be integrated with, and provide the basis for, the requisite level of monitoring.
Consistent with the underlying purposes of the rule,
' Copies are available at current rates from the U.S. Government Printing Office, P.O. Box 37082, Washington, DC 20402-9328 (telephone (202)512-2249);
or from the National Technical. Information Service by writing NTIS at 5285 Port Royal Road, Springfield, VA 22161.
Copies are available for inspection or copying for a fee from the NRC Public Document Room at 2120 L Street NW.,
Washington, DC; the PDR's mailing address is Mail Stop LL-6, Washington, DC 20555; telephone (202)634-3273; fax (202)634-3343.
5
)
maximum flexibility should be offered to licensees in establishing and l
modifying their monitoring activities.
USE OF RELIABILITY-BASED PROGRAMS i
Licensees are encouraged to consider the use of reliability-based methods for developing the preventive maintenance programs covered under 10 CFR 50.65(a)(2); however, the use of such methods is not required.
SAFETY SIGNIFICANCE CATEGORIES The maintenance rule requires that goals be established commensurate with safety.
In order to implement this requirement, NUMARC 93-01 established two safety significance categories, " risk-significant" and "non-risk-significant." The process for placing SSCs in either of these two categories is described in section 9.0 of NUMARC 93-01. The statements of consideration for the rule use the terms "more risk-significant" and "less risk-3 significant." NRC inspection procedure (IP) 62706 uses the terms "high safety significance" and " low safety significance." After discussions with industry representatives, the NRC staff has determined that the preferred terminology is "high safety significance" and " low safety significance." Some licensees may elsct to define other safety significance categories or may elect to define more than two categories, which would be acceptable if these alternative categories are defined in the licensee's procedures and used in a-consistent manner.
SAFETY SIGNIFICANCE RANKING METHODOLOGY The NRC staff endorses the use of the SSC safety significance ranking methodology described in Revision 2 (April 1996) of NUMARC 93-01 as an acceptable method for meeting the requirements of the maintenance rule.'
'The staff is developing guidance that addresses the acceptable criteria for the use of PRAs in risk-informed regulatory matters.
The NRC staff anticipates that a future revision to this Regulatory Guide 1.160 would reference the guidance, when' available, to make the NRC staff's guidance on the use of PRA in the maintenance rule consistent with the NRC staff's guidance in other areas of risk-informed regulation.
The industry will be encouraged to use this guidance at that time.
6
However, because of some unique aspects of the maintenance rule, including the fact that standby SSCs of low safety significance are treated the same as SSCs of high safety significance, this endorsement for purposes of the maintenance rule should not be construed as an endorsement for other applications. These issues were discussed in SECY 95-265, " Response to August 9, 1995, Staff Requirements Memorandum Request to Analyze the Generic Applicability of the Risk Determination Process Used in Implementing the Maintenance Rule."'
APPLICABILITY OF APPENDIX B TO 10 CFR PART 50 With regard to the scope of the maintenance rule, as stated in Paragraph (b) of the rule, it is understood that balance of plant (B0P) SSCs may have been designed and built with normal industrial quality and may not meet the standards in Appendix B to 10 CFR Part 50.
It is not the intent of the NRC staff to require licensees to generate paperwork to document the basis for the design, fabrication, and construction of B0P equipment (i.e., 80P equipment need not meet the requirements of Appendix B to 10 CFR Part 50).
Each licensee's maintenance efforts should minimize failures in both safety-related and B0P SSCs that affect safe operation of the plant.
The effectiveness of maintenance programs should be maintained for the operational life of the facility.
SWITCHYARD MAINTENANCE ACTIVITIES As noted in the Regulatory Position of this guide, there may be a need
)
to address maintenance activities that occur in the switchyards that could directly affect plant operations.
Plant management should be aware of and have the ability to control these activities.
i EMERGENCY DIESEL GENERATORS Industry-and NRC-sponsored probabilistic risk analyses (PRAs) have shown the safety significance of emergency ac power sources.
The station blackout rule (10 CFR 50.63) required plant-specific coping a.nalyses to ensure that a plant could withstand a total loss of ac power for a specified duration and to determine appropriate actions to mitigate the effects of a total loss of ac power.
Du:ing the station blackout reviews, most licensees: (1) made a 7
4
.._m.._
2 -.
J commitment.to implement an emergency diesel generator (EDG) reliability program in accordance with NRC regulatory guidance but reserved the option'to later adopt the outcome of Generic Issue B-56 resolution, and (2) stated that they had or will implement an equivalent program.
Subsequently, utilities docketed commitments to maintain their selected target reliability values (i.e., maintain the emergency diesel generator target reliability.of 0.95 or '
0.975). Those values could be used as a goal or as a performance criterion for emergency diesel generator reliability under the maintenance rule.
l Emergency diesel generator unavailability values were also assumed in j
plant-specific individual plant enmination (IPE) analyses.
These values j
should be compared to the plant-specific emergency diesel generator unavailability data regularly monitored and reported as industry-wide plant performance information.
These values could also be used as the basis for a 4
j goal or_ performance criterion under the maintenance rule.
In addition, in accordance with Paragraph (a)(3) of the rule,. licensees must periodically 1
j
~ balance unavailability and reliability of the emergency diesel generators.
C. REGULATORY POSITION 1-
[
1.
,NUMARC 93-01 I
Revision 2 of NUMARC 93-01, " Industry Guideline for Monitoring the f
Effectiveness of Maintenance at Nuclear Power Plants," provides methods that i
are acceptable'to the NRC staff for complying with the provisions of 10 CFR 50.65 with the following provisions and clarifications.
1.1 Scope of the Rule l
1 j
1.1.1 "Could Cause" Criterion j
During the nine pilot site visits, the NRC staff recognized that some licensees interpreted the words in section 8.2.1.5 of NUMARC 93-01 to mean that only those SSCs that had actually caused a plant scram or safety system I
actuation needed to be included within the scope of the rule.
The NRC staff's position is that the SSCs to be included under the criterion "could cause a reactor scram or actuation of a safety system" should not be limited to SSCs that "did cause" or "could likely cause." This position was discussed in i
.NUREG-1326, " Lessons Learned from Early Implementation of the Maintenance Rule 8
{
4
at Nine Nuclear Power Plants" (June 1995).' Licensees should consider the following SSCs to be within the scope of the rule.
i 1.
SSCs whose failure has caused a reactor scran, or actuation of a safety-related system at their site.
l 2.
SSCs whose failure has caused a reactor _ scram or actuation of a safety-related system at a site with a similar configuration.
3.
SSCs identified in the licensee's analysis (e.g., FSAR, IPE) whose failure would cause a reactor scram or actuation of a safety-q related system.
The only exception to items 2 and 3 above would be a licensee who has demonstrated by an analysis (e.g., FSAR, IPE) and by operational experience
.that the design or configuration of an SSC is fault-tolerant through redundancy or installed standby spares such that a reactor scram or actuation of a safety-related system is implausible.
In these cases, thq licensee may exclude the SSC from the scope of the rule.
1.1.2 SSCs Relied Upon To Mitigate Accidents or Transients or Used in Emergency Operating Procedures Nonsafety-related SSCs that are relied upon to mitigate accidents or transients or that are used in emergency operating procedures (E0Ps) are included in the scope of the rule by 10 CFR 50.65(b)(2)(i).
NUMARC 93-01 states that only those SSCs that provide a significant fraction of the mitigating function need to be included in the scope.of the rule. The NRC staff considers this to mean that SSCs that are directly used to address the accident or transient or explicitly used in the E0Ps are within the scope of the rule, as are SSCs whose use is implied and that provide a significant fraction of the mitigating function.
Examples of SSCs that should be considered include communications and emergency lighting systems, which are necessary to successfully mitigate accidents and transients and to use the E0Ps, although they may not directly address the accident or transient, or not be explicitly mentioned in the E0Ps.
9
1.1.3 Function Versus System The rule provides criteria to determine which SSCs must be included within the scope of the rule. Alternatively, licensees may use a functional basis to determine which SSCs must be monitored within the scope of the rule.
~
That is, the licensee may determine all the functions performed by the SSCs and include within the scope of the maintenance rule only those functions, and
[
the associated SSCs that fulfill those functions, that meet the scoping criteria of the rule.
1.1.4 Systems with Multiple Design Functions For systems that have multiple design functions, the NRC staff's j
position is that some design functions may be within the scope of the
^
maintenance rule while others may be outside the scope of the rule.
Failures of components that affect a design function that is within the scope of the maintenance rule would require corrective action and monitoring under the rule.
For example, the components (piping, pumps, and valves) in the high-pressure coolant injection system (HPCI) that are needed to perform the design function (injection of high-pressure water into the reactor) would be included p
within the scope of the rule because this is a safety-related function of the system.
However, the components that are only used for testing (e.g., test i
loop, sample valves, bypass valves) might be excluded from the scope of the rule unless they meet another scoping criterion (e.g., if they could cause failure of a safety-related SSC), because these components are not required 1
for the coolant injection function of the HPCI.
i 1.2 Definition Of Maintenance For the purposes of the maintenance rule, maintenance activities are as described in the " Final' Commission Policy Statement on Maintenance of Nuclear Power Plants."' This _ definition is very broad and includes all activities associated with the planning, scheduling, accomplishment, post-maintenance l
testing, and return-to-service activities for surveillances and preventive and corrective maintenance. These activities are considered maintenance j
regardless of which organization performs the activity (e.g., maintenance, j
operations, contractors).
This definition is referenced in NUMARC 93-01.
'53 FR 9430. March 23,1988.
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Some licensees have questioned the guidance because in section 9.4.5 of NUMARC 93-01 an example of a failure that is not a maintenance-preventable functional failure (MPFF) is " failures due to operational errors...."
The operational errors referred to in that example are those that are not associated with a maintenance activity.
An example of an operator action that would not be an MPFF would be
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improper closure of a valve while filling a tank that results in a pump trip followed by a reactor trip. An example of an operator action that would be an MPFF could be when an operator failed to reopen a suction valve for a pump following post-maintenance testing and the closed suction valve caused pump failure during a subsequent demand.
1.3 Timeliness NUMARC 93-01 states that activities such as cause determinations and moving SSCs from the (a)(2) to the (a)(1) category must be performed in a
" timely" manner.
Some licensees have requested that the NRC staff provide a 1
specific period that would be considered " timely." To be consistent with the intent of the maintenance rule to provide flexibility to licensees, the NRC j
staff,does not consider it appropriate to provide a specific timeliness I
criterion.
Licensees are to undertake and accomplish activities associated with the maintenance rule in a manner commensurate'with the safety J
significance of the SSC and the complexity of the issue being addressed.
1.4 MPFFs as an Indicator of Reliability NUMARC 93-01 states that performance criteria for SSCs of high safety significance should be established to assure that reliability and availability assumptions used in the plant-specific safety analysis are maintained or adjusted.
NUMARC 93-01 further allows the use of MPFFs as an indicator of reliability.
The maintenance rule requires that the performance of SSCs be monitored commensurate with safety; however, the maintenance rule does not require that the assumptions in the safety analysis be validated.
Licensees who choose to use their safety analyses as described in NUMARC 93-01 must be able to demonstrate how the number of MPFFs allowed per evaluation period is consistent with the assumptions in the risk analysis.
For standby SSCs, this 11 I
would require, at a minimum, a reasonable estimate of the number of demands during that time period.
If a licensee desires to establish a reliability performance criterion that is not consistent with the assumptions used in the risk analysis, adequate technical justification for the performance criterion must be provided.
For some SSCs, an MPFF performance criterion may be too small to be effectively monitored and trended as required by the rule.
In these cases, the licensee should establish performance or condition monitoring criteria that can be monitored and trended so that the licensee can demonstrate that maintenance is effective.
1.5 Monitoring Structures l
The maintenance rule does not treat structures differently from systems and components.
Experience with the rule and NUMARC 93-01 during the pilot site visits and the initial period following the effective date of the rule indicated that specific guidance for monitoring the effectiveness of maintenance for. structures was needed, as structures present a different situation than do systems and components.
The primary difficulty in implem,enting the rule for structures using NUMARC 93-01 was in establishing
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appropriate criteria for performance and monitoring structures under Paragraph (a)(1) instead of Paragraph (a)(2).
The effectiveness of maintenance can be monitored by using performance
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criteria or goals, or by condition mo'nitoring.
While it is acceptable to use performance criteria or goals,. most licensee have found it more practical to use condition monitoring for structures.
With certain exceptions (e.g.,
primary containment), structures do not have unavailability, and rarely have demands placed on their safety significant functions (e.g., maintain integrity under all relevant design basis events), which makes reliability monitoring impractical.
An acceptable structural monitoring program for the purposes of the maintenance rule should have the following attributes.
Consistent with the NUMARC 93-01 approach for systems and components, most structures would be monitored in accordance with Paragraph (a)(2),
provided there is not significant degradation of the structure.
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4 The condition of all structures within the scope of the rule would be assessed periodically.
The appropriate frequency of the assessments would be commensurate with the safety significance of the struqture and its condition.
Licensees would evaluate the results of tl.e assessments to determine the
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extent and rate of any degradation of the structures.
Deficiencies i
would be corrected in a timely manner commensurate with their safety significance, their complexity, and other regulatory requirements.
A structure would be monitored in accordance with Paragraph (a)(1) if either (1) degradation is to the extent that the structure may not meet its design basis or (2) the structure has degraded to the extent that, if the degradation were allowed to continue uncorrected until the next normally scheduled assessment, the structure may not meet its design 2
basis.
The structure would continue to be monitored in accordance with l
Paragraph (a)(1) until the degradation and its cause have been corrected.
,For structures monitored in accordance with Paragraph (a)(1), there would be additional degradation-specific condition monitoring and increased frequency of assessments until the licensee's corrective actions are complete and the licensee is assured that the structure can.
fulfill its intended functions and will not degrade to the point that it i
cannot fulfill its design basis.
4 Consistent with the intent of the rule, licensees should use their existing structural monitoring programs (e.g., those required by other i
regulations or codes) to the maximum extent practical.
1.6 Definition of Standby In NUMARC 93-01, standby SSCs of low safety significance must have SSC-specific performance criteria or goals, similar to SSCs of high safety significance.
NUMARC 93-01 provides a definition of standby.
Some licensees have improperly interpreted this definition as meaning that SSCs that are energized are normally operating.
As stated in NUMARC 93-01, if the SSC only 13
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performs its intended function when initiated by either an automatic or manual demand signal, the SSC is in standby.
Normally operating SSCs are those whose failure would be readily apparent (e.g., a pump failure results in loss of flow that causes a trip).
Standby SSCs are those whose failure would not become apparent until the next j
demand, actuation, or surveillance. Only those SSCs of low safety significance, whose failure would be readily apparent (because they are normally operating), should be monitored by plant-level criteria.
SSCs may have both normally operating and standby functions.
In order to adequately monitor the effectiveness of maintenance for the SSCs associated with standby functions, licensees should develop SSC-specific performance 4
criteria or goals, or condition monitoring.
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1.7 Normally Operating SSCs of Low Safety Significance 1.7.1 Cause Determinations For all SSCs that are being monitored using plant-level performance 4
l criteria (i.e., normally operating SSCs of low safety significance), the NRC staff's position ts that a cause determination is required whenever any of 5
these, performance' criteria are exceeded (failed) in order to determine which SSC caused the criterion to be exceeded or whether the failure was a repetitive MPFF. As part of the cause determination, it would also be necessary to determine whether the SSC was within the scope of the maintenance a
rule and, if so, whether corrective action and monitoring (tracking, trending, goal setting) under 10 CFR 50.65(a)(1) should be performed.
1.7.2 Unplanned Manual Scrams In order to monitor the effectiveness of maintenance for those SSCs monitored by plant-level criteria, NUMARC 93-01 recommends that only those j.
scrams that are automatically initiated be counted.
The NRC staff's' position is that all unanticipated scrams be considered, including those scrams that
'are manually initiated in anticipation of an automatic scram.
The purpose of this is not to discourage manual trips but rather to ensure that operators do not mask a maintenance performance issue.
If ineffective maintenance is i
forcing plant shutdowns, whether the trip is initiated automatically or j
manually should not affect how licensees address the maintenance performance issue under the maintenance rule.
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1.7.3 Establishing SSC-Specific Performance Criteria The maintenance rule requires that licensees monitor the effectiveness of maintenance for all SSCs within the scope of the rule.
NUMARC 93-01 allows licensees to monitor SSCs of low safety significance with plant-level criteria. NUMARC 93-01 notes that some normally operating SSCs of low safety significance cannot be practically monitored by plant-level criteria.
Licensees must ensure that the plant-level criteria established do effectively monitor the maintenance performance of the normally operating SSCs of low safety significance, or they should establish SSC-specific performance criteria or goals or use condition monitoring.
4 For example, a licensee determined that the rod position indication system and the spent fuel pool pit cooling system were within the scope of the maintenance rule because they were safety-related at the licensee's site.
None of the three plant-level performance criteria described in NUMARC 93-01 (unplanned automatic scrams, unplanned capability loss factor, or unplanned safety system actuations) would monitor the effectiveness of maintenance on these systems.
Therefore, additional plant-level performance criteria or system-specific performance criteria must be established.
1.8
, Clarification of MPFFs Related to Design Deficiencies j
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The third paragraph of Section 9.4.5 of NUMARC 93-01 provides guidance on the licensce's options following a failure and on whether, as a result of the licensee's corrective actions, subsequent failures would be considered MPFFs.
In particular, this paragraph addresses failures caused by design deficiencies.
Ideally, licensees would make design modifications to eliminate the poorly designed equipment.
However, if the licensee determines that such an approach is not cost effective (e.g., the cost of modification is i
prohibitive), the licensee has two options:
(1)
Replace or repair the failed equipment and make adjustments to the l
preventive maintenance program as necessary to prevent recurrence sf the failure.
Subsequent failures of the same type that are chused by
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inadequate corrective or preventive maintenance would be MPFFs, atd could be repetitive MPFFs.
l' (2)
Perform an evaluation that demonstrates that the equipment can be run to failure (as described in Section 9.3.3 of NUMARC 93-01).
If the 15 i
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equipment can be run to failure, the licensee can replace or repair the j
i failed equipment, but adjustments to the preventive maintenance program j
1 are not necessary and subsequent failures would not be MPFFs.
1.9 SSCs Considered Under 10 CFR 50.65(a)(1) l Paragraph (a)(1) of the maintenance rule requires that goal setting and 1
monitoring be established for all SSCs within the scope of the rule except for those SSCs whose performance or condition is adequately controlled through the performance of appropriate prevent!.m maintenance as described in Paragraph (a)(2) of the rule.
In NUMARC 93-01, all SSCs are initially placed under j
Paragraph (a)(2) and are only moved under Paragraph (a)(1) if experience i
indicates that the performance or condition is not adequately controlled
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through preventive maintenance as evidenced by the failure to meet a performance criterion or by experiencing a repetitive MPFF.
Therefore, the Paragraph (a)(1) category could be used as a tool to focus attention on those i
SSCs that need to be monitored more closely.
It is possible that no (or very few) SSCs would be handled under the requirements of Paragraph (a)(1).
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However, the rule does not require this approach.
Licensees could also take the approach that all (or most) SSCs would be handled under Paragraph (a)(1) i of the rule and none (or very few) would be considered under Paragraph (a)(2) of the rule.
Licensees may take either approach.
During the pilot site visits, licensees questioned whether a large number of SSCs monitored under Paragraph (a)(1) would be used by the NRC as an indicator of poor maintenance performance.
The NRC staff assured the licensees that NRC management would not use the number of SSCs monitored under l
Paragraph (a)(1) as an indicator of maintenance performance nor would it be j
used in determining the systematic assessment of licensee performance (SALP)
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grade in the maintenance area.
The number of SSCs monitored under Paragraph i
I (a)(1) can vary greatly because of factors that have nothing to do with the quality of the licensee's maintenance activities.
For example, two identical plants with equally effective maintenance programs could have different numbers of SSCs monitored under Paragraph (a)(1) because of differences in the i
way system boundaries were defined (a system with three trains may be defined as one system at one plant while the same system may be defined as three separate systems at an identical plant) or because of differences in the way 4
performance criteria were defined at the two plants (a licensee who takes a 16 i
very conservative approach to monitoring against the performance criteria would have more SSCs in the (a)(1) category). The NRC staff also cautioned licensee managers that they should not view the number of SSCs in the (a)(1) category as an indicator of performance since that attitude might inhibit the licensees' staff from monitoring an SSC under Paragraph (a)(1) when a performance criterion has been exceeded or a repetitive MPFF has occurred.
If there is some doubt about whether a particular SSC should be monitored under Paragraph (a)(1) or Paragraph (a)(2), the conservative approach would be to monitor the SSC under Paragraph'(a)(1).
1.10 Use of Other Methods Licensees may use methods other than those provided in Revision 2 of NUMARC 93-01 to meet the requirements of the maintenance rule, but the NRC will determine the acceptability of other methods on a case-by-case basis.
2.
OTHER DOCUMENTS REFERENCED IN NUMARC 93-01 NUMARC 93-01 references other documents, but NRC's endorsement of NUMARC 93-01.should not be considered an endorsement of the referenced documents.
3.
INCLUSION OF ELECTRICAL DISTRIBUTION E0VIPMENT The monitoring efforts under the maintenance rule, as defined in 10 CFR~
50.65(b), encompass those SSCs that directly and significantly affect plant operations, regardless of what organization actually performs the maintenance activities. Maintenance activities that occur in the switchyard can directly affect plant operations; as a result, electrical distribution equipment out to the first inter-tie with the offsite distribution system (i.e., equipment in the switchyard) should be considered for inclusion as defined in 10 CFR 50.65(b).
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.
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'v Except in those cases in which an applicant or licensee proposes an 3
acceptable alternative method for complying with specified portions of the NRC's regulations, the methods described in this guide will be used in'the I
evaluation of the effectiveness of maintenance activities of licensees who are i
required to comply with 10 CFR 50.65.. The guide will also be used to evaluate the effectiveness of emergency diesel generator maintenance activities associated with compliance with 10 CFR 50.63.
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l REGULATORY AND BACKFIT ANALYSES Separate regulatory and backfit analyses were not prepared for this Revision 2 of Regulatory Guide 1.160.
The regulatory analysis and the backfit
' analysis that were prepared when this guide was first issued as a draft, DG-i 1020, in November 1992, are still applicable.
The backfit analysis prepared for DG-1020 concluded that no backfit was associated with the regulatory guide i
because it was only providing guidance to implement the existing requirements of_the maintenance rule. The Commission determined, on the basis of the j
backfit analysis performed for the maintenance rule, "... that backfitting of the requirements in the maintenance rule will provide a substantial increase j
in the level of protection of public health and safety beyond that currently provided by the Commission's regulations, and that the costs of implementing the rule are justified in view of this increased protection."' The regulatory analysis and backfit analys'is for DG-1020 are available, in the file for Regulatory Guide 1.160, for inspection or copying for a fee in the Co' mission's Public Document Room, 2120 L Street NW., Washington, DC; the m
PDR's mailing address is Mail Stop LL-6, Washington, DC 20555: phone (202)634-
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3273;. fax (202)634-3343.
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'56 FR 31320 j
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