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Guidance on Developing Acceptable Inservice Testing Programs (Generic Letter 89-04)
April 3, 1989 TO: ALL HOLDERS OF LIGHT WATER REACTOR OPERATING LICENSES AND CONSTRUCTION PERMITS SUBJECT: GUIDANCE ON DEVELOPING ACCEPTABLE INSERVICE TESTING PROGRAMS (GENERIC LETTER NO. 89-04) BACKGROUND Paragraph 50.55a(g) of 10 CFR Part 50, "Domestic Licensing of Production and Utilization Facilities," requires that certain ASME Code Class 1, 2, and 3 pumps and valves be designed to enable inservice testing and that testing be performed to assess operational readiness in accordance with the Section XI requirements of the ASME Boiler and Pressure Vessel Code. The inservice testing of ASME Code Class 1, 2, and 3 pumps and valves should be viewed as one part of a broad effort to ensure operational readiness of equipment rather than viewed in the narrow sense as compliance with 10 CFR 50.55a(g). The intent of the testing is to detect degradation affecting operation and assess whether adequate margins are maintained. While this letter has been written to provide guidance reIative to meeting the requirements of 10 CFR 50.55a(g), it is only one part of other ongoing industry and regulatory activities. Recent efforts have been undertaken by the nuclear industry and NRC sponsored research to provide information and techniques for enhanced assurance of equipment operability. NRC staff concerns regarding equipment operability led to the issuance of Bulletin 85-03, dated November 15, 1985, and Bulletin 85-03, Supplement 1, dated April 27, 1988. An expansion of the requirements of this bulletin in the form of a generic letter is being considered by NRC. In addition, NRC is considering rulemaking on IST to develop requirements to address the inadequacies in the current scope and methods of testing per 10 CFR 50.55a(g). Light Water Reactor (LWR) licensees have submitted to the NRC inservice testing (IST) programs for pumps and valves pursuant to 10 CFR 50.55a(g). The editions and addenda applicable to IST program intervals are outlined in 10 CFR 50.55a(g)(4). If the licensee believes that conformance with certain code requirements is impractical, that conformance to the Code would cause unreasonable hardship without a compensating increase in safety or that a proposed alternative provides an acceptable level of quality and safety, 10 CFR 50.55a allows the licensee to request relief from the Code by notifying the Commission and submitting infor-mation to support this determination. Following the evaluation of this infor-mation, the Commission may grant relief and may impose alternative requirements. All IST programs contain requests for relief from various Code requirements. In addition, the surveillance requirements of technical specification (T.S.) 4.0.5 for most plants state that this testing of pumps and valves must be performed in accordance with ASME Section XI except where specific written relief has been granted by the Commission. Because of the general nature of the IST sections of the ASME Code which does not consider plant specific designs and the resulting difficulty in complying with all the ASME Code requirements, utilities frequently revise their programs as more experience with IST is acquired. Programs at most plants are revised several times during the 89033000105 . - 2 - 10 year interval between the program updates required by 10 CFR 50.55a. This trend appears to be continuing even after the programs are updated at the end of the first 10 year interval. The number of program revisions during these 10 year intervals resulted in the need for frequent review by the NRC of licensee's proposed requests for relief from the ASME Section XI requirements and required additional interaction by the NRC with utilities before a Safety Evaluation Report (SER) could be issued. Through reviews and inspections, the NRC staff has identified a number of generic deficiencies that affect plant safety and have frequently appeared as IST program-matic weaknesses. These programmatic weaknesses can be attributed to a lack of understanding in the following areas: (1) Code testing requirements, (2) technical specification requirements, and (3) acceptable alternatives to Code requirements. In order to remedy these generic IST deficiencies, to clarify the status of current programs with respect to applicable T.S. and 10 CFR 50.55a requirements, and to alleviate the problem with respect to review of program revisions, the NRC has established the following guidance. NRC GUIDANCE ON IST PROBLEMS AND IMPLEMENTATION OF IST PROGRAM/REVISIONS A. Introduction Together with the technical specification requirements, IST Programs are intended to ensure the operational readiness of certain safety related pumps and valves. The NRC staff has reviewed and has under review a number of licensee IST programs and relief requests. Based on the review of these programs, and on recent IST inspections, the staff has identified a number of generic deficiencies that potentially affect plant safety. These weaknesses adversely impact the basic objective of the ASME Code, Section XI, IST requirements. Attachment 1 to this Generic Letter contains positions that describe these deficiencies and explain certain ASME Code and T.S. requirements and certain alternatives to the ASME Code that the staff considers acceptable. In addition to the generic deficiencies listed in Attachment 1, the staff has concerns regarding the operability of motor operated valve actuators. These concerns are addressed in Bulletin 85-03, dated November 15, 1985, Bulletin 85-03, Supplement 1, dated April 27, 1988, and Generic Issue II.E.6.1, "In-Situ Testing of Valves." B. Programs Currently Under NRC Review For plants listed in Table 1, the NRC will be issuing an SER in the near future. These plants need not respond with the confirmation letter discussed below. After receipt of the SER, plants in this category should follow the guidance in Part C of this generic letter. For other utilities not listed on either Table 1 or 2, this letter constitutes the required approval for implementation of IST program relief requests provided the utility reviews its program and amends it as necessary to: (1) conform with the Code requirements explained in Attachment 1, Positions 1, 3, 5, and 11; (2) conform with the T.S. requirements explained in Attachment 1, Positions 4 and 8; and (3) conform with the applicable Code requirement or the staff approved alternatives in Attachment 1, Positions 1, 2, 6, 7, 9, and 10. . - 3 - Based on the staff's experience the positions contained in Attachment 1 can be implemented at all plants. However, should licensees be unable to comply with one of these positions because of design considerations or personnel hazard, as opposed to inconvenience, any alternative testing must fulfill the basic test objective of detecting component degradation. Alternative testing should be individually evaluated by the licensee and the licensee's plant safety review committee (or equivalent). When evaluating testing, licensees should address the following: 1. Maintenance history of the individual (specific) component, 2. Maintenance history of the related components in a similar environment, 3. Component vendor records of degradation at other facilities, and 4. Records on degradation of the same or like component from other utilities. Licensees may utilize in-plant records, the NPRDS and other referenceable sources to compile data to address the above four areas. A lack of service experience or test results by itself is not sufficient to justify the alternative test. The alternative test is not considered acceptable unless the above data is sufficient to justify its adequacy for detecting degradation and ensuring continued operability. Justification for the alternative test should be documented and retained in the IST program. For plants not listed on either Table 1 or 2, currently submitted IST program relief requests are hereby approved for licensees who have not received an SER provided that they (1) review their most recently submitted IST programs and implementation procedures against the positions delineated in Attachment 1 and (2) within 6 months of the date of this letter confirm in writing their conformance with the stated positions. In cases where conformance with the stated positions would result in equipment modifications, the licensee should provide in his confirmation letter a schedule for completing the required modifications. All modifications must be completed within 18 months of the date of the confirmatory letter, whichever occurs later. Changes to the IST programs as a result of this generic letter, should be submitted to the NRC along with the confirmation letter. Approval is granted provided the programs are consistent with the positions taken in Attachment 1 or, for positions that necessitate a plant modification, will be consistent with Attachment 1 on the schedule noted above. Where a deviation needs to be taken from a specific position in Attachment 1, the approval is granted provided the adequacy of the proposed alternative testing for detecting degradation is justified as discussed above. C. Programs With Completed NRC Reviews For the plants listed in Table 2 the staff has completed its review of the IST program and issued an SER. These plants need not respond with the confirmation letter discussed above. The status of the relief requests approved in the SER is not affected by this letter. The relief requests that were approved in the SER may continue to be implemented, and those that were denied should be . - 4 - resolved in accordance with the guidance in the SER. The technical positions found in Attachment 1 of this generic letter were used by the staff in reviews of IST programs. If licensees have modified or plan to modify their IST program beyond that which was the basis for the staff's SER, the guidance in Part D below should be used. D. Program Updates/Revisions If the licensees modify their IST program beyond that currently submitted to the NRC, they should review the modifications against the positions found in Attachment 1. For IST program changes for which specific positions are provided in Attachment 1, licensees should follow the guidance in Section B above. For IST program changes in areas not covered by Attachment 1, the provisions of 10 CFR 50.55(a)g should be followed. The modified program should comply with the disposition of relief requests in any applicable SER based on a previously submitted IST program. E. Implementing Procedures IST programs contain basic information on the pumps and valves being tested, the type of tests being performed, and the frequency of testing, but not the procedures being followed. The positions in Attachment 1 primarily address generic short-comings in IST programs. However, each of these positions, as well as other areas of the ASME Code, are dependent upon the adequacy of the implementing procedures. This letter provides guidance to be taken relative to the positions in Attachment 1 to correct deficiencies in the IST programs. The implementing procedures for these positions should likewise be reviewed and amended to address any deficiencies related to implementation of these positions. F. Inspection and Enforcement The NRC may conduct inspections to determine licensee conformance with the provisions of the approval granted by this letter. Enforcement action against licensees may result in cases where the program and procedures are not in confor-mance with 10 CFR 50.55a(g), as explained in this guidance. The areas covered in Attachment 1 will be the focus of future IST inspections. Aspects of the IST programs not addressed by Attachment 1 may also be inspected. IST PROGRAM APPROVAL This generic letter approves currently submitted IST program relief requests for licensees who have not received an SER provided that they (1) review their most recently submitted IST programs and implementation procedures against the positions delineated in Attachment 1 and (2) within 6 months of the date of this letter confirm in writing their conformance with the stated positions. Since the IST program reviews for licensees listed on Table 1 are nearly complete, they will receive relief request approvals by separate correspondence. By addressing the technical areas identified in Attachment 1, the staff has concluded that certain significant deficiencies in the IST programs and in IST relief requests will be corrected. Other deficiencies related to assurance of . - 5 - the operational readiness of pumps and valves have been or will be the subject of regulatory actions such as generic letters and rulemaking. Provided the provisions of this letter are followed, the staff has determined that relief is granted to follow the alternative testing delineated in positions 1, 2, 6, 7, 9, and 10, pursuant to 10 CFR 50.55a(g)(6)(i), is authorized by law, and will not endanger life or property or the common defense and security and is otherwise in the public interest. In making this determination the staff has considered the impracticality of performing the required testing considering the burden if the requirements were imposed. This request is covered by Office of Management and Budget Clearance Number 3150-0011 which expires December 31, 1989. The estimated average burden hours is 700 man-hours per owner response, including assessment of the new recom- mendations, searching data sources, gathering and analyzing the data, and preparing the required letters. These estimated average burden hours pertain only to these identified response-related matters and do not include the time for actual implementation of the requested actions. Comments on the accuracy of this estimate and suggestions to reduce the burden may be directed to the Office of Management and Budget, Room 3208, New Executive Office Building, Washington, D.C. 20503, and the U.S. Nuclear Regulatory Commission, Records and Reports Management Branch, Office of Administration and Resources Manage- ment, Washington, D.C. 20555. Sincerely, Steven A. Varga, Acting Associate Director for Projects Office of Nuclear Reactor Regulation Enclosures: Tables 1 and 2 w/Attachment 1 . TABLE 1 PLANTS WITH SERs TO BE ISSUED IN NEAR FUTURE Beaver Valley 1 Peach Bottom 2&3 Braidwood 1&2 Rancho Seco Brunswick River Bend Calvert Cliffs 1&2 Robinson 2 Clinton Seabrook 1 Comanche Peak SONGS 2&3 D.C. Cook 1&2 St. Lucie 2 Farley 1&2 Summer Ft. Calhoun Surry 1&2 Hatch 1&2 Vogtle 1 Hope Creek Waterford 3 Kewaunee Wolf Creek Limerick 1&2 WNP 2 McGuire 1&2 Zion 1&2 Millstone 2 Nine Mile Point 1 Nine Mile Point 2 . TABLE 2 PLANTS WITH CURRENT IST PROGRAMS REVIEWED AND SER ISSUED Browns Ferry 1,2&3 Byron 1&2 Davis Besse 1 Diablo Canyon 1&2 Calloway Fermi 2 Millstone 3 Palo Verde 1,2&3 Prairie Island 1&2 Sequoyah 1&2 Shearon Harris South Texas 1&2 TMI 1 Vogtle 2 . ATTACHMENT 1 POTENTIAL GENERIC DEFICIENCIES RELATED TO IST PROGRAMS AND PROCEDURES 1. Full Flow Testing of Check Valves Section XI of the ASME Code requires check valves to be exercised to the positions in which they perform their safety functions. A check valve's full-stroke to the open position may be verified by passing the maximum required accident condition flow through the valve. This is considered by the staff as an acceptable full-stroke. Any flow rate less than this will be considered a partial-stroke exercise. A valid full-stroke exercise by flow requires that the flow through the valve be known. Knowledge of only the total flow through multiple parallel lines does not provide verification of flow rates through the individual valves and is not a valid full-stroke exercise. Full flow testing of a check valve as described above may be impractical to perform for certain valves. It may be possible to qualify other techniques to confirm that the valve is exercised to the position required to perform its safety function. To substantiate the acceptability of any alternative technique for meeting the ASME Code requirements, licensees must as a minimum address and document the following items in the IST program: 1. The impracticality of performing a full flow test, 2. A description of the alternative technique used and a summary of the procedures being followed, 3. A description of the method and results of the program to qualify the alternative technique for meeting the ASME Code, 4. A description of the instrumentation used and the maintenance and calibration of the instrumentation, 5. A description of the basis used to verify that the baseline data has been generated when the valve is known to be in good working order, such as recent inspection and maintenance of the valve internals, and 6. A description of the basis for the acceptance criteria for the alternative testing and a description of corrective actions to be taken if the acceptance criteria are not met. An acceptable alternative to this full-stroke exercising requirement is stated in position 2 below. . - 2 - 2. Alternative to Full Flow Testing of Check Valves. The most common method to full-stroke exercise a check valve open (where disk position is not observable) is to pass the maximum required accident flow through the valve. However, for some check valves, licensees cannot practically establish or verify sufficient flow to full-stroke exercise the valves open. Some examples of such valves are, in PWRs, the contain- ment spray header check valves and combined LPSI and safety injection accumulator header check valves and, in BWRs, the HPCI or RCIC check valves in the pump suction from the suppression pool. In most commercial facili-ties, establishing design accident flow through these valves for testing cou1d result in damage to major plant equipment. The NRC staff position is that valve disassembly and inspection can be used as a positive means of determining that a valve's disk will full- stroke exercise open or of verifying closure capability, as permitted by IWV-3522. If possible, partial valve stroking quarterly or during cold shutdowns, or after reassembly must be performed. The staff has established the following positions regarding testing check valves by disassembly: a. During valve testing by disassembly, the valve internals should be visually inspected for worn or corroded parts, and the valve disk should be manually exercised. b. Due to the scope of this testing, the personnel hazards involved and system operating restrictions, valve disassembly and inspection may be performed during reactor refueling outages. Since this fre-quency differs from the Code required frequency, this deviation must be specifically noted in the IST program. c. Where the licensee determines that it is burdensome to disassemble and inspect all applicable valves each refueling outage, a sample disassembly and inspection plan for groups of identical valves in similar applications may be employed. The NRC guidelines for this plan are explained below: The sample disassembly and inspection program involves grouping similar valves and testing one valve in each group during each refueling outage. The sampling technique requires that each valve in the group be the same design (manufacturer, size, model number, and materials of construction) and have the same service conditions including valve orientation. Additionally, at each disassembly the licensee must verify that the disassembled valve is capable of full-stroking and that the internals of the valve are structurally sound (no loose or corroded parts). Also, if the disassembly is to verify the full-stroke capability of the valve, the disk should be manually exercised. . - 3 - A different valve of each group is required to be disassembled, inspected, and manually full-stroke exercised at each successive refueling outage, until the entire group has been tested. If the disassembled valve is not capable of being full-stroke exercised or there is binding or failure of valve internals, the remaining valves in that group must also be disassembled, inspected, and manually full-stroke exercised during the same outage. Once this is completed, the sequence of disassembly must be repeated unless extension of the interval can be justified. Extending the valve sample disassembly and inspection interval from disas- sembly of one valve in the group every refueling outage or expanding the group size would increase the time between testing of any particular valve in the group. With four valves in a group and an 18-month reactor cycle, each valve would be disassembled and inspected every six years. If the fuel cycle is increased to 24 months, each valve in a four-valve sample group would be disassembled and inspected only once every 8 years. Extension of the valve disassembly/inspection interval from that allowed by the Code (quarterly or cold shutdown frequency) to longer than once every 6 years is a substantial change which may not be justified by the valve failure rate data for all valve groupings. When disassembly/ inspection data for a valve group show a greater than 25% failure rate, the licensee should determine whether the group size should be decreased or whether more valves from the group should be disassembled during every refueling outage. Extension of the valve disassembly/inspection interval to one valve every other refueling outage or expansion of the group size above four valves should only be considered in cases of extreme hardship where the extension is supported by actual in-plant data from previous testing. In order to support extension of the valve disassembly/inspection intervals to longer than once every 6 years, licensees should develop the following information: a. Disassemble and inspect each valve in the valve grouping and document in detail the condition of each valve and the valve's capability to be full-stroked. b. A review of industry experience, for example, as documented in NPRDS, regarding the same type of valve used in similar service. c. A review of the installation of each valve addressing the "EPRI Applications Guidelines for Check Valves in Nuclear Power Plants" for problematic locations. 3. Back Flow Testing of Check Valves. Section XI requires that Category C check valves (valves that are self actuated in response to a system characteristic) performing a safety function in the closed position to prevent reversed flow be tested in a manner that proves that the disk travels to the seat promptly on cessation or reversal of flow. In addition, for category A/C check valves (valves that . - 4 - have a specified leak rate limit and are self actuated in response to a system characteristic), seat leakage must be limited to a specific maximum amount in the closed position for fulfillment of their function. Verifica-tion that a Category C valve is in the closed position can be done by vis-ual observation, by an electrical signal initiated by a position-indicating device, by observation of appropriate pressure indication in the system, by leak testing, or by other positive means. Examples of ASME Code Class check valves that perform a safety function in the closed position that are frequently not back flow tested are: a. main feedwater header check valves b. pump discharge check valves on parallel pumps c. keep full check valves d. check valves in steam supply lines to turbine driven AFW pumps e. main steam non-return valves f. CVCS volume control tank outlet check valves 4. Pressure Isolation Valves a. General Pressure isolation valves (PIVs) are defined as two normally closed valves in series that isolate the reactor coolant system (RCS) from an attached low pressure system. PIVs are located at all RCS low pressure system interfaces. The 10 CFR 50.2 contains the definition of the RCPB. PIVs are within the reactor coolant pressure boundary (RCPB). The following summary is based upon the staff's review of responses to Generic Letter 87-06, Periodic Verification of Leak Tight Integrity of Pressure Isolation Valves. All plants licensed since 1979 have a full list of PIVs in the plant Technical Specifications (TS) along with leak test requirements and limiting conditions for operation (LCOs). The plants licensed prior to 1979 fall into several categories. Some pre-1979 plants have a full list of PIVs along with leak test requirements and LCOs in the plant TS. Some pre-1979 plants have only Event V PIVs (see below) in the plant TS. Some pre-1979 plants have no TS requirements regarding PIVs. All PIVs listed in plant TS should be listed in the IST program as Category A or A/C valves. The TS requirements should be referenced in the IST program. b. Event V PIVs Event V PIVs are defined as two check valves in series at a low pressure/RCS interface whose failure may result in a LOCA that by- passes containment. Event V refers to the scenario described for this event in the WASH-1400 study. . - 5 - On April 20, 1981, the NRC issued an Order to 32 PWRs and 2 BWRs which required that these licensees conduct leak rate testing of their PIVs, based on plant-specific NRC supplied lists of PIVs, and required licensees to modify their TS accordingly. These orders are known as the "Event V Orders" and the valves listed therein are the "Event V" PIVs. The Event V PIVs are a subset of PIVs. Based upon the results of recent inspections, it has been determined that the following implementation problem still exists with respect to testing of PIVs. The staff has determined that in some cases the procedures are inadequate to assure that these valves are individually leak tested and evaluated against the leakage limits specified in the TS; in other cases, the procedures were adequate but were not being followed. Specifically, some check valves were tested in series as opposed to individually and some check valves were not tested when required. Licensees should review their testing procedures to ensure the Event V PIVs are individually leak rate tested. 5. Limiting Values of Full-Stroke Times for Power Operated Valves The Code intent with respect to measuring the full-stroke times of power operated valves is to verify operability and to detect valve degradation. Measurement of full stroke times for air operating valves fulfills this intent. However, reviews of operating experience have identified several problems with motor operated valves (MOVs) including limitations with stroke time as a measure of operational readiness of the MOV. As a result, the industry has made extensive efforts to improve the knowledge and under-standing of operational characteristics of motor operated valves. This effort has been conducted by industry groups (NUMARC, INPO, NMAC, EPRI), individual licensees, equipment vendors, and national standards groups. We believe the information and knowledge developed by these groups should be reviewed and utilized. Some of the information publicly available includes an INPO white paper titled, "Motor-Operated Valve Performance Update," issued October 4, 1988. This document identifies MOV problem areas and provides the key elements for a comprehensive MOV program. Another document is the "Technical Repair Guidelines for the Limitorque Model SMB-000 Valve Actuator," issued by the Nuclear Maintenance Applica- tion Center (NMAC) in January 1989. This guide addresses several areas such as setting torque and limit switches, preventive maintenance, actuator failure modes, failure analysis to determine root cause and corrective action, and preoperational and post-maintenance testing. NRC staff concerns regarding MOV operability led to the issuance of Bulletin 85-03 and Bulletin 85-03, Supplement 1. Expansion of this bulletin in the form of a generic letter is being considered by the NRC. . - 6 - In spite of the limitations of stroke time testing of MOVs, IWV-3413(a) of the ASME Code requires that the licensee specify the limiting value of full-stroke time of each power operated valve. The corrective actions of IWV-3417(b) must be followed when these limiting values are exceeded. The Code does not provide any requirements or guidelines for establishing these limits nor does it identify the relationship that should exist between these limits and any limits identified for the relevant valves in the plant TS or safety analysis. The purpose of the limiting value of full-stroke time is to establish a value for taking corrective action on a degraded valve before the valve reaches the point where there is a high probability of failure to perform its safety function if called upon. The NRC has, therefore, established the guidelines described below regarding limiting values of full-stroke time for power operated valves. The limiting value of full-stroke time should be based on the valve reference or average stroke time of a valve when it is known to be in good condition and operating properly. The limiting value should be a reasonable deviation from this reference stroke time based on the valve size, valve type, and actuator type. The deviation should not be so restrictive that it results in a valve being declared inoperable due to reasonable stroke time variations. However, the deviation used to establish the limit should be such that corrective action would be taken for a valve that may not perform its intended function. When the TS or safety analysis limit for a valve is less than the value established using the above guidelines, the TS or safety analysis limit should be used as the limiting value of full-stroke time. When the TS or safety analysis limit for a valve is greater than the value established using the above guidelines, the limiting value of full-stroke time should be based on the above guidelines instead of the TS or safety analysis limit. 6. Stroke Time Measurements for Rapid-Acting Valves The Code requires the following for power operated valves with stroke times 10 seconds or less: (a) Limiting values of full-stroke times shall be specified [IWV-3413(a)], (b) Valve stroke times shall be measured to (at least) the nearest second [IWV-3413(b)] and (c) If the stroke time increases by 50% or more from the previous test, then the test frequency shall be increased to once each month until corrective action is taken [IWV-3417(a)]. Paragraph IWV-3417(b) specifies corrective actions that must be taken. With reference to (c) above, measuring changes in stroke times from a reference value as opposed to measuring changes from the previous test is an acceptable (and possibly better) alternative to the staff. However, since this is different from the Code requirement, this deviation should be documented in the IST program. . - 7 - Most plants have many power operated valves that are capable of stroking in 2 seconds or less such as small solenoid operated valves. Licensees encounter difficulty in applying the Code 50% increase of stroke time corrective action requirements for these valves. The purpose of this requirement is to detect and evaluate degradation of a valve. For valves with stroke times in this range, much of the difference in stroke times from test to test comes from inconsistencies in the operator or timing device used to gather the data. These differences are compounded by rounding the results as allowed by the Code. Thus, the results may not be representative of actual valve degradation. The following discussion illustrates the problem that may exist when complying with the Code requirements for many of these rapid-acting valves: A valve may have a stroke time of 1.49 seconds during one test and a stroke time during the following test of 1.51 seconds. If stroke times are rounded to the nearest second as allowed by the Code, the difference between these tests would exceed the 50% criteria and would require an increased frequency of testing until corrective action is taken. This can result from a stroke time difference of 0.02 seconds, which is usually not indicative of significant valve degradation. Power operated valves with normal stroke times of 2 seconds or less are referred to by the staff as "rapid-acting valves." Relief may be granted from the requirements of Section XI, Paragraph IWV-3417(a) for these valves provided the licensee assigns a maximum limiting value of full-stroke time of 2 seconds to these valves and, upon exceeding this limit, declares the valve inoperable and takes corrective action in accordance with IWV-3417(b). An acceptable alternative to the Code stroke timing requirements is the above stated rapid-acting valve position. Since this represents a devi- ation from the Code requirements, it should be specifically documented in the IST program. 7. Testing Individual Control Rod Scram Valves in Boiling Water Reactors (BWRs) BWRs are equipped with bottom-entry hydraulically driven control rod drive mechanisms with high-pressure water providing the hydraulic power. Each control rod is operated by a hydraulic control unit (HCU), which consists of valves and an accumulator. The HCU is supplied charging and cooling water from the control rod drive pumps, and the control rod operating cylinder exhausts to the scram discharge volume. Various valves in the control rod drive system perform an active function in scramming the control rods to rapidly shut down the reactor. The NRC has determined that those ASME Code Class valves that must change position to provide the scram function should be included in the IST program and be tested in accordance with the requirements of Section XI except where relief has been granted in a previously issued Safety Evaluation Report or as discussed below. . - 8 - The control rod drive system valves that perform an active safety function in scramming the reactor are the scram discharge volume vent and drain valves, the scram inlet and outlet valves, the scram discharge header check valves, the charging water header check valves, and the cooling water header check valves. With the exception of the scram discharge volume vent and drain valves, exercising the other valves quarterly during power operations could result in the rapid insertion of one or more control rods more frequently than desired. Licensees should test these control rod drive system valves at the Code-specified frequency if they can be practically tested at that frequency. However, for those control rod drive system valves where testing could result in the rapid insertion of one or more control rods, the rod scram test frequency identified in the facility TS may be used as the valve testing frequency to minimize rapid reactivity transients and wear of the control rod drive mechanisms. This alternate test frequency should be clearly stated and documented in the IST program. Industry experience has shown that normal control rod motion may verify the cooling water header check valve moving to its safety function position. This can be demonstrated because rod motion may not occur if this check valve were to fail in the open position. If this test method is used at the Code required frequency, the licensee should clearly explain in the IST program that this is how these valves are being verified to close quarterly. Closure verification of the charging water header check valves requires that the control rod drive pumps be stopped to depressurize the charging water header. This test should not be performed during power operation because stopping the pumps results in loss of cooling water to all control rod drive mechanisms and seal damage could result. Additionally, this test cannot be performed during each cold shutdown because the control rod drive pumps supply seal water to the reactor recirculation pumps and one of the recirculation pumps is usually kept running. Therefore, the HCU accumulator pressure decay test as identified in the facility TS may be used as the charging water header check valve alternate testing frequency for the reasons stated above. If this test is not addressed in the licensee's TS this closure verification should be performed at least during each refueling outage, and this alternate test frequency should be specifically documented in the IST program. The scram inlet and outlet valves are power operated valves that full-stroke in milliseconds and are not equipped with indication for both positions, therefore, measuring their full-stroke time as required by the Code may be impractical. Verifying that the associated control rod meets the scram insertion time limits . - 9 - defined in the plant TS can be an acceptable alternate method of detecting degradation of these valves. Also, trending the stroke times of these valves may be impractical and unnecessary since they are indirectly stroke timed and no meaningful correlation between the scram time and valve stroke time may be obtained, and furthermore, conservative limits are placed on the control rod scram insertion times. If the above test is used to verify the operability of scram inlet and outlet valves, it should be specifically documented in the IST program. 8. Starting Point for Time Period in TS ACTION Statements ASME Section XI, IWP-3220, states "All test data shall be analyzed within 96 hours after completion of a test." IWP-3230(c) states, in part, "If the deviations fall within the 'Required Action Range' of Table IWP-3100-2, the pump shall be declared inoperative,...." In many cases pumps or valves covered by ASME, Section XI, Subsections IWP and IWV, are also in systems covered by TS and, if declared inoperable, would result in the plant entering an ACTION statement. These ACTION statements generally have a time period after which, if the equipment is still inoperable, the plant is required to undergo some specific action such as commence plant shutdown. The potential exists for a conflict between the aforementioned data analysis interval versus the TS ACTION statement time period. Section XI, IWP-6000 requires the reference values, limits, and acceptance criteria to be included in the test plans or records of tests. With this information available, the shift individual(s) responsible for conducting the test (i.e., shift supervisor, reactor operator) should be able to make a timely determination as to whether or not the data meets the requirements. When the data is determined to be within the Required Action Range of Table IWP-3100-2 the pump is inoperable and the TS ACTION statement time starts. The provisions in IWP-3230(d) to recalibrate the instruments involved and rerun the test to show the pump is still capable of fulfilling its function are an alternative to replacement or repair, not an additional action that can be taken before declaring the pump inoperable. The above position, which has been stated in terms of pump testing, is equally valid for valve testing. In summary, it is the staff's position that as soon as the data is recog- nized as being within the Required Action Range for pumps or exceeding the limiting value of full-stroke time for valves, the associated component must be declared inoperable and the TS ACTION time must be started. . - 10 - 9. Pump Testing using Minimum-flow Return Line With or Without Flow Measuring Devices An inservice pump test requires that the pump parameters shown in Table IWP-3100-1 be measured and evaluated to determine pump condition and detect degradation. Pump differential pressure and flow rate are two parameters that are measured and evaluated together to determine pump hydraulic performance. Certain safety-related systems are designed such that the minimum-flow return lines are the only flow paths that can be utilized for quarterly pump testing. Furthermore, some of these systems, do not have any flow path that can be utilized for pump testing during any plant operating mode except the minimum-flow return lines. In these cases, pumping through the path designed for fulfilling the intended system safety function could result in damage to plant equipment. Minimum-flow lines are not designed for pump testing purposes and few have installed flow measuring devices. In cases where flow can only be established through a non-instrumented minimum-flow path during quarterly pump testing and a path exists at cold shutdowns or refueling outages to perform a test of the pump under full or substantial flow conditions, the staff has determined that the increased interval is an acceptable alternative to the Code requirements provided that pump differential pressure, flow rate, and bearing vibration measurements are taken during this testing and that quarterly testing also measuring at least pump differential pressure and vibration is continued. Data from both of these testing frequencies should be trended as required by IWP-6000. Since the above position is a deviation from the Code required testing, it should be documented in the IST program. In cases where only the minimum-flow return line is available for pump testing, regardless of the test interval, the staff's position is that flow instrumentation which meets the requirements of IWP-4110 and 4120 must be installed in the mini-flow return line. Installation of this instrumentation is necessary to provide flow rate measurements during pump testing so this data can be evaluated with the measured pump differ- ential pressure to monitor for pump hydraulic degradation. NRC Bulletin 88-04, dated May 5, 1988, advised licensees of the potential for pump damage while running pumps in the minimum-flow condition. The above guidelines for meeting the Code or performing alternative testing is not intended to supersede the thrust of this Bulletin. Licensees should ensure that if pumps are tested in the low flow condition, the flow is sufficient to prevent damage to the pump. . - 11 - 10. Containment Isolation Valve Testing All containment isolation valves (CIVs) that are included in the Appendix J, program should be included in the ISI program as Category A or A/C valves. The staff has determined that the leak test procedures and requirements for containment isolation valves specified in 10 CFR 50, Appendix J are equivalent to the requirements of IWV-3421 through 3425. However, the licensee must comply with the Analysis of Leakage Rates and Corrective Action requirements of Paragraph IWV-3426 and 3427(a). IWV-3427(b) specifies additional requirements on increased test frequencies for valve sizes of six inches and larger and repairs or replacement over the requirements of IWV-3427(a). Based on input from many utilities and staff review of testing data at some plants, the usefulness of IWV-3427(b) does not justify the burden of complying with this requirement. Since this position represents a deviation from the Code requirements, it should be documented in the IST program. 11. IST Program Scope The 10 CFR 50.55a requires that inservice testing be performed on certain ASME Code Class 1, 2, and 3 pumps and valves. Section XI Subsections IWP-1100 and IWV-1100 defines the scope of pumps and valves to be tested in terms of plant shutdowns and accident mitigation. The plant's FSAR (or equivalent) provides definitions of the necessary equipment to meet these functions. The staff has noted during past IST program reviews and inspections that licensees do not always include the necessary equipment in their IST programs. Licensees should review their IST programs to ensure adequate scope. Examples that are frequently erroneously omitted from IST programs are: a. BWR scram system valves, b. control room chilled water system pumps and valves, c. accumulator motor operated isolation valves, or accumulator vent valves, d. auxiliary pressurizer spray system valves, e. boric acid transfer pumps, f. valves in emergency boration flow path, g. control valves that have a required fail-safe position, h. valves in mini-flow lines. It should be recognized that the above examples of pumps and valves do not meet the IWP/and IWV scope statement requirements for all plants. The intent of 10 CFR 50 Appendix A, GDC-1, and Appendix B, Criterion XI, is that all components, such as pumps and valves, necessary for safe operation are to be tested to demonstrate that they will perform satisfactorily in service. Therefore, while 10 CFR 50.55a delineates the testing requirements for ASME Code Class 1, 2, and 3 pumps and valves, the testing of pumps and valves is not to be limited to only those covered by 10 CFR 50.55a.
Page Last Reviewed/Updated Friday, June 28, 2013