ML20140C731
| ML20140C731 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 04/15/1997 |
| From: | Boger B NRC (Affiliation Not Assigned) |
| To: | Jain S DUQUESNE LIGHT CO. |
| References | |
| RTR-REGGD-01.160, RTR-REGGD-1.160, TASK-*****, TASK-RE NUDOCS 9704180109 | |
| Download: ML20140C731 (3) | |
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UNITED STATES NUCLEAR REGULATORY COMMISSION f
WASHINGTON, D.C. 20555-0001
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April 15, 1997 Mr. Sushil C. Jain Division Vice President Nuclear Services Nuciar Power Division Duquesne Light Company Beaver Valley Power Station P.O. Box 4 Shippingport, Pennsylvania 15077-0004
SUBJECT:
RESPONSE TO NOVEMBER 11,1996, LETTER PROVIDING COMMENTS ON DRAFT REGULATORY GUIDE 1051," MONITORING THE EFFECTIVENESS OF MAINTENANCE AT NUCLEAR POWER PLANTS"
Dear Mr. Jain:
Thank you for providing comments on Draft Regulatory Guide 1051 (DG-1051), " Monitoring the Effectiveness of Maintenance at Nuclear Power Plants," which was the proposed Revision 2 to Regulatory Guide 1.160 (RG 1.160) of the same title. In March 1997, the staff i
issued RG 1.160, Revision 2, a copy of which is enclosed. This letter provides the staff's response to the comments on DG-1051 provided in your letter dated November 11,1996.
1 Your letter provided two comments on DG-1001. The first comment was that Section 1.2 of 1
DG-1051 (now Section 1.1.4 of RG 1.160, Revision 2), " Systems With Multiple Design I
Functions," could be misconstrued to imply that scoping needed to be performed at a component level rather than at a system level. The staff believes that the guidance in the draft and regulatory guide is sufficiently clear that scoping can be performed at the system 1
level. The intent of Section 1.1.4 is that licensees have the flexibility to exclude from scope those portions of a system that do not meet the scoping requirements in 10 CFR 50.65(b) of i
the maintenance rule. An additional clarification was made in RG 1.160, Revision 2, in Section 1.1.3, " Scoping By Function Versus System." This section notes that an acceptable attemative to scoping by system is to scope by function. That is, licensees only need to include in the scope of the rule the structures, systems, or components (SSCs) associated with functions that meet the scoping criteria of the rule (e.g., safety related, could cause a j
scram, used in emergency operating procedures...).
The second comment was that Section 1.3 of DG-1051 (now Section 1.7.1 of RG 1.160, Revision 2), "Cause Determinations," improperly implied that if an SSC within the scope of the maintenance rule failed to meet a performance criterion or had a repetitive maintenance preventable functional failure (MPFF), then the SSC was automatically required to be monitored in accordance with Paragraph (a)(1) of the rule. The not automatically have to monitor SSC performance in accordance with Paragraph (a)(1) if the SSC fails to meet a performance criterion or has a repetitive MPFF, and the staff has revised Section 1.7.1 of RG 1.160, Revision 2, accordingly. However, in most instances,
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S. C. Jain failing to meet a performance criterion or experiencing a repetitive MPFF would be expected to result in SSC performance being monitored in accordance with Paragraph (a)(1).
If you have any questions regarding the staff's response to your comments, please contact Mr. Richard P. Correia, Chief, Reliability and Maintenance Section, Quality Assurance and Maintenance Branch, (301) 415-1009.
Sincerely, Bruce A. Boger, Director Division of Reactor Controls and Human Factors Office of Nuclear Reactor Regulation Docket Nos. 50-334 and 50-412
Enclosure:
RG 1.160, Revision 2 cc with enclosure: See next page
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S. C. Jain Beaver Valley Power Station Dusquesne Light Company Units 1 & 2 cc:
Jay E. Silberg, Esquire Bureau of Radition Protection Shaw, Pittman, Potts & Trowbridge Pennsylvania Department of 2300 N Street, N.W.
Environmental Resources Washington, DC 20037 ATTN: R. Barkanic Post Office Box 2063 R. K. Brosi, Manager Harrisburg, PA 17120 Nuclear Safety Department (BV-A) j Beaver Valley Power Station Mayor of the Borrough of P.O. Boy. 4 Shippingport Shippingport, PA 15077 Post Office Box 3 l
Shippingport, PA 15077 Commissioner Roy M. Smith West Virginia Department of Labor Rgional Administrator, Region i Bui: ding 3, Room 319 U.S. Nuclear Regulatory Commission Capitol Complex 475 Allendale Road Charleston, WVA 25305 King of Prussia, PA 19406 John D. Borrows Resident inspector Director, Utilities Department U.S. Nuclear Regulatory Commission Public Utilities Commission Post Office Box 298 180 East Broad Street Shippingport, PA 15077 Columbus, OH 43266-0573 Mr. J. E. Cross Director, Pennsylvania Emergency President-Generation Group Management Agency Duquesne Light Company Post Office Box 3321 Post Office 4 Harrisburg, PA 17105-3321 Shippingport, Pa 15077-0004 Ohio EPA-DERR ATTN: Zack A. Clayton Post Office Box 1049 Columbus, OH 43266-0149 Dr. Judith Johnsrud National Energy Committee Sierra Club 433 Orlando Avenue State College, PA 16803
e U.S. NUCLEAR REGULATORY COMMISSION Revision 2 l
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REGULATORY GUIDE g
Ma'ch 1997
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OFFICE OF NUCLEAR REGULATORY RESEARCH REGULATORY GUIDE 1.160 (Draft was DG-1051)
MONITORING THE EFFECTIVENESS OF MAINTENANCE AT NUCLEAR POWER PLANTS i
A. INTRODUCTION consistent with the NRC's defense-in-depth philoso-The NRC published the maintenance rule on phy. Maintenance is also important to ensure that de-July 10,1991, as Section 50.65, " Requirements for sign assumptions and margins in the original design ba-Momtoring the Effectiveness of Maintenance at Nu-sis are maintained and are not unacceptably degraded.
clear Power Plants," of 10 CFR Part 50," Domestic Li-
%erefore, nuclear power plant maintenance is clearly censing of Production and Utilization Facilities." The importam in protecting public health and safety.
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NRC's determination that a maintenance rule was Paragraph (a)(1) of 10 CFR 50.65 requires that needed arose from the conclusion that proper mainte.
power reactor licensees monitor the performance or nance is essential to plant safety. As discussed in the condition of SSCs against licensee-established goals in regulatory analysis for this rule,I there is a clear link be.
a manner sufficient to provide reasonable assurance tween effective maintenance and safety as it relates to that such SSCs are capable of fulfilling their intended such factors as the number of transients and challenges functions. Such goals are to be established commensu-y to safety systems and the associated need for operabil.
rate with safety and, where practical, take into account ity, availability, and reliability of safety equipment. In industry-wide operating experience. When the perfor-i addition, good maintenance is also important in provid.
mance or condition of an SSC does not meet estab-ing assurance that failures of other than safety-related lis5ed goals, appropriate corrective action must be Mk-structures, systems, arid components (SSCs) that could en. For a nuclear power plant for which the licensee has initiate or adversely affect a transient or accident are submitted the certifications specified in 10 CFR minimized. Minimizing challenges to safety systems is 50.82(a)(1) (i.e., plants undergoing decommissioning),
Paragraph (a)(1) of 10 CFR 50.65 applies only to the NRC Memorandum to All Commissioners from J. Taylor on **Mainte-extent that the licensee must monitor the performance 1
nance Rulemaking," June 27,1991. Copics are available for inspection or or Condition of all $$Cs associated with storing, con-N, ngion, I$ ihYkoNn'aN"ad [reDaii sNp$' 'd, trolling, and maintaining spent fuel in a safe condition, washington, oc 20555; phone (202)634-3273; fax (202)634-3343 in a manner sufficient to provide reasonable assurance USNRC Rt GURA10RY GUIDES The guices.o issued m the loNowing ten broad descons Reguistory Guides are. sued to casenbe arid make eveelable to thepubhc suchird.ma-hon as methods acceptable to,. NRC staff for ernp.manhng spec #g pans of t.Com-1 Poww Reactors 6 Products and data needed N
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that such SSCs are capable of fulfilling their intended (i) That are relied upon to mitigate accidents j
functions.
or transients or are used in plant emergen-Paragraph (a)(2) of 10 CFR 50.65 states that moni-cy perating procedures (EOPs); c toring as specified in Paragraph (a)(1) is not required (ii) Whose failure could prevent safety-where lt has been demonstrated that the performance or related structures, systems, and compo-condition of an SSC is being effectively controlled nents from fulfilling their safety-related through the performence of appropriate preventive function; or maintenance, such that the SSC remams capable of per-forming its intended function.
(iii) Whose failure could cause a reactor Paragraph (a)(3) of 10 CFR 50.65 requires that per.
scram or actuatinn of a safety-related formance and condition monitoring activities and asso.
system.
ciated goals and preventive maintenance activities be Paragraph (c) of 10 CFR 50.65 states that the rule i
evaluated at least every refueling cycle provided the in-provisions are to be implemented by licensees no later i
terval between evaluations does not exceed 24 months.
than July 10,1996.
The evaluations must be conducted taking into accour.t, where practical, industry-wide operating experience.
This Regulatory Guide 1.160 is being revised to Adjustments must be made where necessary to ensure endorse Revision 2 of NUMARC 934)1, " Industry that the objective of preventing failures of SSCs Guidehne for Monitoring the Effectiveness of Mainte-through maintenance is appropriately balanced against nance at Nuclear Power Plants"4 (April 1996), which the objective of minimizing unavailability of SSCs be-has been updated by the Nuclear Energy Institute. The cause of monitoring or preventive maintenance. In per-regulatory guManu is intended to provide flexibility forming monitoring and preventive maintenance activ-f r a Hansee to structure its maintenance program in aqcordance w th the safety significance of those SSCs i
ities, an assessment of the total plant equipment that is out ofservice should be taken into account to determine within the scope of the rule.
the overall effect on performance of safety functions.
The information collections contained in this regu-Paragraph (b) of 10 CFR 50.65 states that the scope i t ry guide are covered by the requirements of 10 CFR of the monitoring program specified in Paragraph Part 50, which were approved by the Olfice of Manage-(a)(1) is to include safety-related and nonsafety-related ment and Budget, approval number 31504)011. The j
SSCs as follows.
NRC may not conduct or sponsor, and a person is not i
required to respond to, a collection of information un-(1) Safety-related stractures, systems, or compo.
less it displays a currently valid OMB control number.
nents that are relied upon to remain functional during and following design basis events to B. DISCUSSION ensure the integrity of the reactor coolant pres-sure bour.dary, the cap.bility to shut down the OBJECTIVE reactor and maintain it in a safe shutdown con-The objective of 10 CFR 50.65 (referred to hereaf-i dition, and the capability to prevent or mitigate ter as the m ntenance rule or the rule) is to require the consequences of accidents that could result monitoring ot the overall continuing effectiveness of li-in potential offsite exposure comparable to the censee maintenance programs to ensure that (1) safety-guidelines in 10 CFR 50.34(a)(1) or 100.11 of related and certain nonsafety-related SSCs are capable this chapter, as applicable.3 of performing their intended functions and (2) for non-(2) Nonsafety-related structures, systems,orcom-safety-related equipment, failures will not occur that prevent the fulfillment of safety-related functions, and ponents:
failures resulting in scrams and unnecessary actuations 2The speciric requirements for decommissioning plants became effective August 28,1996. see 61 FR 39278, July 19,1996,"Decommissiomng of Nuclear Power Reactors?
3This Paragraph (b)(1) of the maintenance rule w as changed in the fmal
'This document is available for inspection or copying for a fee in the NRC rulemaking for" Reactor Site Cntena includmg seismic and Earthquake Pubhc Document Room,2120 L Street NW., Washington, DC; the PDR's Engmeenng Cntena for Nucleat Po wer Plants," December i1,1996. see mohng address is Mail stop ll.-6, Washington. DC 20555; phone 6i FR 65157.
(202)634-3273; fa x (202)634-3343.
1.160 - 2
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DEVELOPMENT OF INDUSTRY GUIDELINE, PLANT, SYSTEM, TRAIN, AND COMPONENT j
NUMARC 93-01 MONITORING LEVELS q
The nuclear industry developed a docontem, The extent of monitoring may vary from system to (v)
NUMARC 93-01," Industry Guideline for Monitoring system depending on the system's importance to safety.
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the Effectiveness of Maintenance at Nuclear Power Some raonitoring at the component level may be neces-Plants"(May 1993),4 hat provides guidance to licen-sary; however,it is envisioned that most of the monitor-t l
sees regarding implementation of the maintenance rule, ing could be done at the plant, system, or train level.
This document was prepared by NUMARC. A verifica-SSCs with high safety significance and standby SSCs
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tion and validation (V&V) effort was conducted by with low safety significance should be monitored at the NUMARC, with NRC staff observation, to test the system or train level. Except as noted in the Regulatory guidance document on several representative systems.
Position of this guide, normally operating SSCs with A number of changes were made to the NUMARC low safety significance may be monitored through guidance document based on the resuits of the V& V ef-plant-level performance criteria, including unplanned fort. The NRC staff reviewed this document and found scrams, safety system actuations, or unplanned capa-I that it provided acceptable guidance to licensees. In bility loss factors. For SSCs monitored in accordance June 1993, the NRC staff issued Regulatory Guide with 10 CFR 50.65(a)(1), additional parameter trend-1.160, " Monitoring the Effectiveness of Maintenance ing may be necessary to ensure that the problem that at Nuclear Power Plants," which endorsed the May caused the SSC to be placed in the Paragraph (a)(1) 1993 version of NUMARC 93 -01. In January 1995, the category is being corrected.
NRC staffissued Revision I to Regulatory Guide 1.160 to reflect the amendment to 10 CFR 50.65(a)(3) that USE OF EXISTING LICENSEE PROGRAMS changed the requirement for performing the periodic The NRC staff encourages licensees to use, to the evaluation from annually to once per refueling cycle, maximum extent practicable, activities currently being not to exceed 24 months between evaluations.
conducted, such as technical specification surveillance From September 1994 to March 1995, the NRC
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" 8 '#9" ities could be m. tegrated with, and provide the basis for, staff performed a series of nm.e pilot site visits to verify the usability and adequacy of the draft NRC mainte-the requisite level of monitoring. Consistent with the
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nance rule inspection procedure and to determine the underlying purposes of the rule, mrximum flexibility strengtha and weaknesses of the implementation of the should be offered to licensees in establishing and modi-rule at each site that used the guidance provided in NU-fying their monitoring activities.
MARC 93-01. ihe findings are described in USE OF RELIABILITY-BASED PROGRAMS NUREG-1523, " Lessons Learned from Early Imple-Licensees are encouraged to consider the use of mentation of the Maintenance Rule at Nine Nuclear reliability-based methods for developing the preven-Power Plants"5 (June 1995). The NRC staff concluded tive maintenance programs covered under 10 CFR that the requirements of the rule could be met more con-50.65(a)(2); however, the use of such methods is not sistently across the industry if some clarifying guid-required.
J ance was added to NUM ARC 93-01 to address the fin-dings noted in NUREG-1526. The NRC staff met with SAFETY SIGNIFICANCE CATEGORIES industry representatives in a series of public meetings The maintenance rule requires that goals be estab-to discuss proposed revisions to NUMARC 93-01 that lished commensurate with safety. In order to imple-would address the findings noted during the site visits.
m,:nt this requirement, NUMARC 93-01 established Revision 2 to NUMARC 93-01 (April 1996) resulted two safeiy significance categories, " risk-significant" from these meetings.
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-Copies are available at current rates from the U.s. Government Pnntmg significant" and "less risk-significant." NRC inspec-5 4
Office. P.o. Box 37082. Washmgton, DC 20402-9328 (telephone tion procedure (IP) 62706 uses the terms "high safety l
(202>512-2249); or from ihe Nationai Technicat information service by significance" and " low safety significance." After dis-u ntmg NTis at 5285 Port Roy al Road, springfield. VA 22161. Copies t
cussions with. dustry representatives, the NRC staff are available for inspection or copying for a fee from the NRC Public in
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Document Room at 2120 L street NW.. washington. DC; the PDR's mailmg address is Mail stop 11-6, Washington. DC 20555; telephone has determined that the preferred terminology is "higl (202)634-3273; fax (202)634-3343.
safety s,gm,fiCance" and " low safety sigmficance.,,
1 1.160 -3
Some licensees may elect to define other safety signifi-plant operations. Plant management should be aware of cance categories or may elect to define more than two and have the ability to control these activities.
categories, which would be acceptable if these alterna-EMERGENCY DIESEL GENERATORS tive categories are defined in the licensee's procedures and used in a consistent manner.
Industry-and NRC-sponsored probabilistic risk analyses (PRAs) have shown the safety significance of SAFETY SIGNIFICANCE RANKING emergency ac power sources. The station blackout rule METilODOLOGY (10 CFR 50.63) required plant-specific coping analyses The NRC staff endorses the me of the SSC safety to ensure that a plant could withstand a total loss of ac significance ranking methodology described in Revi.
power for a specified duration and to deternJne ap-sion 2 (April 1996) of NUMARC 93-01 as an accept-propriate actions to mitigate the effects of a totalloss of able method for meeting the requirements of the main-ac power. During the station blackout reviews, most li-tenance rule.6 Ilowever, because of some unique cernees: (1) made a commitment to implement an aspects of the maintenance rule, including the fact the emergency diesel generator (EDG) reliability program standby SSCs oflow safety significance are treated the in accordance with NRC regulatory guidance but re-same as SSCs of high safety significance, this endorse-served the option to later adopt the outcome of Generic ment for purposes of the maintenance rule should not be issue B-56 resolution, and (2) stated that they had or construed as an endersement for other applications.
will implement an equivalent program. Subsequently, These issues were discussed in SECY 95-265, "Re-utilities docketed commitments to maintain their se.
sponse to August 9,1995, Staff Requirements Memo-lected target reiiability values (i.e., maintain the emer-randum Request to Analyze the Generic Applicability gency diesel generator target reliability of 0.95 or of the Risk Determination Process Used in Implement-0.975). Those values could be used as a goal or as a per-ing the Maintenance Rule."4 formance criterion for emergency diesel generatot reli-ability under the maintenance rule.
APPLICABILITY OF APPENDIX B TO 10 CFR PART 50 Emergency diesel generator unavailability values were also assumed in plant-specific individual plant ex-With regard to the scope of the maintenance rule, as amination (IPE) analyses. These values should be stated in Paragraph (b) of the rule, it is understood that compared to the plant-specific emergency diesel gener-balance of plant (IlOP) SSCs may have been designed ator unavailability data regularly monitored and re-and built with normal industrial quality and may not ported as industry-wide plant performance informa-meet '.he standards in Appendix B to 10 CFR Part 50. It tion. These values could also be used as the basis for a is not the intent of th:: NRC staff to require licensees t" goal or performance criterion under the maintenance generate paperwork to docmnt the basis for the de-rult. in addition,in accordance with Paragraph (a)(3) of sign, fabrication, and construction of BOP equipment the rule, licensees must periodically balance unavai!-
(i.e., BOP equipment need not meet the requirements of ability and reliability of the emergency diesel Appendix B to 10 CFR Part 50).
Senerators.
Each licensee's maintenance efforts should mini-C. REGULATORY POSITION mize failures in both safety-related and BOP SSCs that affect safe operation of the plant. The effectiveness of 1.
NUMARC 93-01 maintenance programs should be maintained for the Revision 2 0f NUMARC 93-01," Industry Guide-operationallife of the facility.
I ne for Monitoring the Effectiveness of Maintenan.e at SWITCIIYARD MAINTENANCE ACTIVITIES Nuclear Power Plants,"4 provides methods that are ac-ceptable to the NRC staff for complying with the provi-As noted in the Regulatory Position of this guide, sions of 10 CFR 50.65 with the following provisions
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there may be a need to address maintenance activities and clarifications.
that occur in the switchyards that could directly affect 1.1 Scope of the Rule
- ne siafr is de,eioping guidance ihar addresses the acceptadie enteria 1.1.1 "Could Cause Criterion for the use of PRAs in nsk-inf.wd e:ulatmy matters. The NRC staff anheinstes that a future resision to th$ Regulator) Guide 1.160 would During the nine pilot site Visits, the NRC staff rec-reference the guidance,. 9 as nhble, to make the NRC staff's guid-ognized that some licensees interpreted the words in ance on the use of PR A in t.+ en :nw~.nce rule conCstent with the NRC staff's guidance in other arcam of risk. informed regulation. The industry section 8.2.1.5 of NUMARC 93-4)1 to mean that only will he encouraged 10 une thi= guidance at that time.
those SSCs that had actually caused a plant scram or 1.160 - 4
1 safety system actuation needed to be included within 1.I.3 Function Versus System the reope of the rule. The NRC staff N position is that The rule provides criteria to determine which SSCs the SSCs to be included under the criterion "could must be included within the scope of the rule. Alterna-(C}
cause a reactor scram or actuation of a safety system" tively, licensees may use a functional basis to determine should not be limited to SSCs that "did cause" or which SSCs must be monitored within the scope of the "could likely cause." This position was discussed in rule. That is, the licensee may determine all the func-NUREG-1526, " Lessons Learned from Early imple-tions performed by the SSCs and include within the mentation of the Maintenance Rule at Nine Nuclear scope of the maintenance rule only those functions, arlJ Power Plants"(June 1995).5 Licensees should consider the associated SSCs that fulfill those functions, that the following SSCs to be within the scope of the rule.
meet the scoping criteria of the rule.
1.
SSCs whose failure has caused a reactor scram 1.1.4 Systems with Multiple Design Functions or actuation of a safety-related system at their For systems that have multiple design functions, site.
the NRC staff's position is that some design functions may be within the scope of the maintenance rule while 2.
SSCs whose failure has caused a reactor scram others may be outside the scope of the rule. Failures of or actuation of a safety-related system at a site components that affect a design function that is within with a similar configuration.
the scope of the maintenance rule would require correc-tive action and monitoring under the rule. For example.
3.
SSCs identified in the licensee's analysis (e.g.,
the compcnents (piping, pumps, and valves) in the FSAR, JPE) whose failure would cause a reac-high-pressure coolant injection system (llPCI) that are for scram or actuation of a safety-related needed to perform the design function (injection of system.
high-pressure water into the react ) would be included
.The only exception to items 2 and 3 above would within the scope of the rule because this is a safety-be a licensee who has demonstrated by an analysis (e.g.,
related function of the system. Ilowever, the compo-g\\
FSAR, IPE) and by operational experience that the de-nents that are only used for testing (e.g., test loop, sam-
)
sign or configuration of an SSC is fault-tolerant ass valves) might be excluded from the v
through redundancy or installed standby spares such scope of the rule unless they meet another scoping crite-that a reactor scram or actuation of a safety-related sys-rion (e.g., if they could cause failure of a safety-related tem is implausible. In these cases, the licensee may ex-SSC), because these components are not required for clude the SSC from the scope of the rule.
the coolant injection function of the IIPCI.
1.2 Definition of Maintenance 1.1.2 SSCs Relied Upon To Mitigate For the purposes of the maintenance rule, mainte-Accidents or Transients or Used in nance activities are as described in the " Final Commis-Emergency Operating Procedures sion Policy Statement on Maintenance of Nuclear Pow-Nonsafety-related SSCs that are relied upon tomit-er Plants."7 This definition is very broad and includes igate accidents or transients or that are used in emergen-all activities associated with the planning, scheduling, cy operating procedures (EOPs) are included in the accomplishment, post-maintenance testing, and return-scope of the rule by 10 CFR 50.65(b)(2)(i). NUMARC to-service activities for surveillances and preventive 934)1 states that only those SSCs that provide a signifi-and corrective maintenance. These activities are con-cant fraction of the mitigating function need to be in-sidered maintenance regardless of which organization cluded in the scope of the rule. The NRC staff considers performs the activity (e.g., maintenance, operations.
this to mean that SSCs that are directly used to address contractors). This definition is referenced in the accident or transient or explicitly used in the EOPs NUMARC 934)l. Some licensees have questioned the are within the scope of the rule, as are SSCs whose use guidance because in section 9.4.5 of NUM ARC 93--01 is implied and that provide a significant fraction of the an example of a failure that is not a maintenance mitigating function. Examples of SSCs that should be preventable functional failure (MPFF) is " failures due considered include communications and emergency to operational errors.. " The operational errors referred l
lighting systems, which are necessary to successfully to in that example are those that are not associated with n
j mitigate accidents and transients and to use the EOPs, a maintenance activity.
v' although they may not directly address the accident or transient, or not be explicitly mentioned in the EOPs.
7531R 9430, March 23.1988.
1.160 - 5
An example of an operator action that would not be 1.5 Monitoring Structures an MPFF would be improper closure of a valve while The maintenance rule does not treat structures dif-hlling a tank that results in a pur ' rip followed by a ferently from systems and components. Experience 1
reactor trip. An example of an operator action that with the rule and NUMARC 9341 during the pilot site would be an MPFF could be when an operator failed to visits and the initial period following the effective date reopen a suction valve for a pump following post-of the rule indicated that specific guidance for monitor-maintenance testing and the closed suction vahe ing the effectiveness of maintenance for structures was caused pump failure during a subsequent demand.
needed, as structures present a different situation than 1.3 T,imeliness do systems and components. The primary difficulty in implementing the rule for structures using NUMARC NUMARC 934)1 states that activities such as 934)1 was in establishing appropriate criteria for per-cause determinations and moving SSCs from the (a)(2) formance and monitoring structures under Paragraph to the (a)(1) category must be performed in a " timely" (a)(1) instead of Paragraph (a)(2).
manner. Some licensees have requested that the NRC Tk WMive of maimenance can be moni-staff provide a specific period that would be considered 1
" timely." To be consistent with the in.ent of the mainte-tored by using performance criteria or goals, or by con-nance rule to provide Hexibility to licensees, the NRC dition monitoring. While it is acceptable to use perfor-staff coes not consider it appropriate to provide a spe-mance criteria or goals, most licensees have found it cific timelmess criterion. Licensees are to undertake more practical to use condition monitoring for struc-and accomplish activities associated with the mainte-tures. With certain exceptions (e.g., primary contain-nance rule in a manner commensurate with the safety ment), structures do not have unavailability, and rarely sigmficance of the SSC and the complexity of the issue hve demands placed on their safety sigmficant func-being addressed ^
tions (e.g., maintain integrity under all relevant design basis events), which makes reliability monitoring 1.4 MPFFs as an Indicator of Reliability impractical.
NUMARC 93-01 states that performance criteria An acceptable structural monitoring program for for SSCs of high safety significance should be estab-the purposes of the maintenance rule should have the lished to assure that reliability and availability assump-following attributes.
tions used in the plant-specific safety analysis are main-tained or adjusted. NUM ARC 934)1 further allows the Consistent with the NUMARC 93-01 ap-l use of MPFFs as an indicator of reliability. The mainte-proach for systems and components, most structures would be monitored in accordance I
nance rule requires that the performance of SSCs be I
with Paragraph (a)(2), provided there is not monitored commensurate with safety; however, the significant degradation of the structure.
J maintenance rule does not require that the assumptions in the safety analysis be validated. Licensees who The condition of all structures within the scope a
choose to ase their safety analyses as described in of the rule would be assessed periodically. The NUMARC 934)1 must be able to demonstrate how the appropriate frequency of the assessments number of MPFFs allowed per evaluation period is would be commensurate with the safety signif-consistent with the assumptions in the risk analysis. For icance of the structure and its condition.
standby SSCs, this would require, at a minimum, a rea-Licensees would evaluate the results of the sonable estimate of the number of demands during that time period.
assessments to determine the extent and rate of any degradation of the structures. Deficiencies If a licensee desires to establish a reliability perfor-would be corrected in a timely manner mance criterion that is not consistent with the assump-commensurate with their safety significance, tions used in the risk analysis, adequate technical justi-their complexity, and other regulatory fication for the performance criterion must be provided.
requirements.
For some SSCs, an MPFF performance criterion may be too small to be effectively monitored and trended as A structure would be monitored in accordance required by the rule. In these cases, the licensee should with Paragraph (a)(1) if either (1) degradation i
establish performance or condition monitoring criteria is to the extent that the structure may not meet that can be rnonitored and trended so that the licensee its design basis or (2) the structure has de-can demonstrate that maintenance is effective, graded to the extent that, if the degradation 1.160 - 6
.m.,
I f
were allowed to continue uncorrected until the 1.7 Normally Orerating SSCs of Low Safety l
next normally scheduled assessment, the Signincance i
- struct.re may not meet its design basis. The 1.7.1 Cause Determinations structure would continue to be monitortJ m accordance with Paragraph (a)(1) until the For all SSCs that are being monitored using plant-degradation and its cause have been corrected.
level performance criteria (i.e., normally operating SSCs oflow safety significance), the NRC staff's posi-l tion is that a cause determination is required whenever any of these performance criteria are exceeded (failed)
{
For structures monitored m, accordance with in order to determine which SSC caused w criterion to Paragraph (a)(1), there wot..
ae additional be exceeded or whether the failure was a repetitive I
degradation-specific condition monitoring MPFF. As part of the cause determination, it would also l[
l and increased frequency of assessments until be necessary to determine whether the SSC was within g
the licensee's corrective actions are comp!:te the scope of the maintenance rule and, if so, whether
- j and the licensee is assured that the structure corrective action and monitoring (tracking, trending, i.
can fulfill its intended functions and will not goal setting) under 10 CFR 50.65(a)(1) should be I
degrade to the point that it cannot fulfill its de-performed.
sign basis.
1.7.2 Unplanned Manual Scrams Consistent with the intent of the rule, licenseu in order to monitor the effectiveness of mainte-should use their existing structural monitoring pro nance for those SSCs monitored by plant-level criteria, l
grams (e.g., those required by other regulations or NUMARC 934)1 recommends that only those scrams l
codes) to the maximum extent practical.
that are automatically initiated be counted. The NRC staff's position is that all unanticipated scrams be con-sidered, including those scrams that are manually initi-l 1.6 Dennition of Standby ated in anticipation of an automatic scram. The purpose l
of this is not to discourage manual trips but rather to en-in NUMARC 934)l, standby SSCs of low safety sure that operators do not mask a maintenance perfor-significance must have SSC-specific performance cri-mance issue. If ineffective maintenance is forcing plant teria or goals, similar to SSCs of high safety signifi-shutdowns, whether the trip is initiated automatically cance. NUM ARC 934)1 provides a definition of stand-or manually should not affect how licensees address the by, Some licensees have improperly interpreted this maintenance performance issue under the maintenance definition as meaning that SSCs that are energized are rule.
normally operating. As stated in NUMARC 93411,if the SSC only performs its intended function when initi.
1.7.3 Establishing SSC-Specific Performance ated by either an automatic or manual demand signal, Criteria the SSC is in standby.
The maintenance rule requires that licensees moni-tor the effectiveness of maintenance for all SSCs within Normally operating SSCs are those whose failure the scope of the rule. NUMARC 93-01 allows licen-would be readily apparent (e.g., a pump failure results sees to monitor SSCs of low safety significance with i
in loss of flow that causes a trip). Standby SSCs are plant-level criteria. NUMARC 934)1 notes that some j
those whose failure would not become apparent until normally operating SSCs of low safety significance the next demand, actuation, or surveillance. Only those cannot be practically monitored by plant-level criteria.
I SSCs of low safety significance, whose failure would Licensees must ensure that the plant-level criteria es-be readily apparent (because they are normally operat.
tablished do effectively monitor the maintenance per-ing), should be monitored by plant-level criteria.
formance of the normally operating SSCs oflow safety significance, or they should establish SSC-specific per-l' SSCs may have both normally operating and f rmance criteria or goals or use condition monitoring.
standby functions. In order to adequately monitor the For example, a licensee determined that the rod effectiveness of maintenance for the SSCs associated position indication system and the spent fuel pool pit
)
with standby functions, licensees should develop SSC-cooling system were within the scope of the mainte-specific performance criteria or goals, or condition nance rule because they were safety-related at the li-i monitoring.
censee's site. None of the three plant-level performancs 1.160 - 7
~!
criteria described in NUMARC 934)1 (unplanned automatic scrams, unplanned capability toss factor, or ing a repetitive MPFF. Therefore, the Paragraph (a)(1) unplanned safety system actuations) would monitor the category could be used as a tool to focus attention on efectiveness of maintenance on these systems. There-those SSCs that need to be monitored more closely. It is fore, additional plant-level perforrnance criteria or possibk that no (or very few) SSCs would be handled under the requirements of Paragrapt (a)(1). However, system-specific performance criteria must be established, the rule does not require this approach. Licensees could also take the approach that all(or most)SSCs would be 1.8 Cicrification of MPFFs Related to Design handled under Paragraph (a)(1) of the rule and none (or i
Dcficiencies very few) would be considered under Paragraph (a)(2) of the rule. Licensees may take either approach.
The third paragraph of Section 9.4.5 of NUMARC 93-4)1 provides guidance on the licensee's options fol-During the pilot site visits, licensees questioned lowing a failure and on whether, as a result of the licens-whether a large number of SSCs monitored under Para-evs corrective actions, subsequent failures would be graph (a)(1) would be used by the NRC as an indicator considered MPFFs. In particular, this paragraph ad-of ooor m imen nee per rmance. The NRC staff as-dresses failures caused by design deficiencies. Ideally, sure e
ensees that NRC managernent would not licensees would make design modifications to elimi-use the number of SSCs monitored under Paragraph nate the poorly designed equipment, flowever,if he li-I"U ) "" "" '" 'ator ntenance perknance w t
censee determines that such an approach is not cost ef-would it be used m. determinmg the systematic assess-j fective (e.g., the cost of modification is prohibitive),
ment of licensee performance (SALP) grade m the the licensee has two options:
maintenanct nrea. The number of SSCs monitored un-der Paragraph (a)(1) can vary greatly because of factors (1) Replace or repair the failed equipment and that have nothiag to do with the quality of the licensee's make adjustments to the preventive mainte-maintenance activities. For example, two identical nance program as necessary to prevent recur-plants with equally effective maintenance programs rence of the failure. Subsequent failures of the could have different numbers of SSCs monitored under same type that are caused by madequate cor-Paragraph (a)(1) because of differences in the way sys-rective or preventive maintenance would be k>m Noundaries were defined (a system with three trains MPFFs, and could be repetitive MPFFs.
may be defined as one system at one plant while the I
system may be defined as three separate systems (2) Perform an evaluation that demonstrates that at an identical plant) or because of differences in the the equipment can be run to failure (as de-way performance criteria were defined at the twoplants scribed in Section 9.3.3 of NUMARC 93-4)l).(a licensee who takes a very conservative approach to if the equipment can be run to failure, the li-monitoring against the performance criteria would censee can replace or repair the failed equip-has e more SSCs in the (a)(1) category). The NRC staff ment, but adjustments to the preventive main-also cautioned licensee managers that they should not tenance program are not necessary and view the number of SSCs in the (a)(1) category as an subsequent failures would not be MPFFs.
indicator of performance since that attitude might in-
'hibit the licensees' staff frem monitoring an SSC under
).9 SSCs Considered Under 10 CFR 50.65(a)(1) Paragraph (a)(1) when a performance criterion has been Paragraph (a)(1) of the maintenance rule requires exceeded or a repetitive MPFF has occurred. If there is hat goal setting and monitoring be established for all some doubt about whether a particular SSC should be monitored under Paragraph (a)(1) or Paragraph (a)(2).
SCs within the scope of the rule except for those SSCs the conservative approach would be to monitor the SSC hose performance or condition is adequately con-under Paragraph (a)(1).
olled through the performance of appropriate preven-
,ve maintenance as described in Paragraph (a)(2) of the I. In NUM ARC 93411, all SSCs are initially placed 1.10 Use of Other Methods
.le nder Parg,raph (a)(2) and are only moved under Para.
Licensees may use methods other than those pro-aph (a)(1) if experience indicates that the perfor-vided in Revision 2 of NUMARC 934)1 to meet the re-ance or condition is not adequately controlled quirements of the maintenance rule, but the NRC will rough preventive maintenance as evidenced by the determine the acceptability of other methods on a case-(
_ilure to meet a performance criterion or by experienc-by-case basis.
1.160 - 8
2.
OTIIER DOCUMENTS REFERENCED IN (i.e., equipment in the switchyard) should be consid-NUMARC 93-01 ered for inclusion as defined in 10 CFR 50.65(b).
NUMARC 93-01 references other documents,1,ut NRC's endorsement of NUMARC 93-01 should not be D. IMPLEMENTATION considered an endorsement of the referenced documents.
The purpose of this section is to provide informa-tion to applicants and licensees regarding the NRC 3.
INCLUSION OF ELECTRICAL staff's plans for using this regulatory guide.
DISTRIBUTION EOUIPMENT Except in those cases in which an applicant or h.-
censee proposes an acceptable alternative method for The monitoring efforts under the maintenance rule, complying with specified portions of the NRC's regu-as defined in 10 CFR 50.65(b), encompass those SSCs lations, the methods described in this guide will be used that directly and significantly affect plant operations, in the evaluation of the effectiveness of maintenance regardless of what organization actually performs the activities oflicensees who are required to comply v 'h d
maintenance activities. Maintenance activities that oc-10 CFR 50.65. The guide will also be used to evaluate cur in the switchyard can directly affect plant opera-the effectiveness of emergency diesel generator mainte-tions; as a result, electrical distribution equipment out nance activities associated with compliance with 10 to the first inter-tie with the offsite distribution system CFR 50.63.
1.160 - 9
REGULATORY AND IIACKFIT ANALYSES Separate regulatory and backfit analyses were not prepared for this Revision 20f Regulatory Guide 1.160.
the level of protection of public health and safety be-The regulatory analysis and the backfit analysis that yond that currently provided by the Commission's reg-were prepared when this guide was first issued as a ulations, and that the costs ofimplementing the rule are draft, DG-1020, in November 1992, are still applica-justified in view of this increased protection."' The re-ble. The backfit analysis prepared for DG-1020 con-gulatory analysis and backfit analysis for DG-1020 are cluded that no backfit was associated with the regulato-available, in the file for Regulatory Guide 1.160, for in-ry guide because it was only providing guidance to spection or copying for a fee in the Commission's Pub-implement the existing requirements of the mainte-lic Document Room,2120 L Street NW., Washington, nance rule. The Commission determined, on the basis DC; the PDR's mailing address is Mail Stop LL-6, of the backfit analysis performed for the maintenance Washington, DC 20555: phone (202)634-3273: fax (202)634-3343.
rule, "
that backfitting of the requirements in the maintenance rule will provide a substantial increase in
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