NRC Generic Letter 1984-13
UNITED STATESt l oNUCLEAR REGULATORY COMMISSIONWASHINGTON, D. C. 20555May 3, 1984To All Power Reactor Licensees (Except SEP Licensees) AndAll Applicants For Licenses To Operate Power ReactorsSubject: Technical Specification For Snubbers (Generic Letter 84-13)For several years a technical specification for snubbers has been included inthe technical specifications for new facility operating licenses. A modelspecification was transmitted to power reactor licensees as Revision 1 ofthe Surveillance Requirements for snubbers by an enclosure to my GenericLetter of November 20, 1980.During the last several years, a large number of license amendments have beenrequired to add, delete or modify the snubber listing within the technicalspecifications. We have reassessed the inclusion of snubber listings within thetechnical specifications and conclude that such listings are not necessaryprovided the snubber technical specification is modified to specify whichsnubbers are required to be operable. You should also note that the record-keeping requirements of paragraph 4.9.7.f. of the snubber technical speci-fication are not altered by this revision. Paragraph 4.9.7.f. requires thatthe plant records contain a record of the service life, installation date,etc. of each snubber. Since any changes in snubber quantities, types, orlocations would be a chance to the facility, such changes would be subjectto the provisions of 10 CFR Part 50.59 and, of course, these changes wouldhave to be reflected in the records required by paragraph 4.7.9.f.Enclosed is a revision to Revision 1 of the Surveillance Requirements whichwas attached to my Generic Letter of November 20, 1980. This revision islimited to a modification to Specification 3.7.9 to specify which snubbersare subject to the requirements of this technical specification and to theelimination of Tables 3.7-4a and 3.7-4b. Specification 3.7.9 now includesas part of the Limiting Condition for Operation the same criterion as was inthe bases section of my November 20, 1980 Generic Letter. This criterionstates that all snubbers other than specified exceptions are required to beoperable. The requirement in Specification 3.7.9 of Revision 1, that snubbersbe listed in Tables 3.7-4a and 3.7-4b is no longer necessary and is eliminatedby this revision.5040043/ 7 / EX 3 3 I--2-No change in existing technical specifications that include a list of snubbersis required. However, a licensee may choose to request a license amendment todelete the tabular listing of snubbers from its technical specifications.Unless and until deleted, the list of snubbers shall be maintained in accordancewith the requirements of Revision 1 of the Surveillance Requirements for snubbersthat was enclosed with my Generic Letter of November 20, 1980.A few recently issued licenses have included technical specifications withouttabular listings of snubbers. This revision will be applied to futureoperating licenses and the technical specifications will not include lists ofsnubbers.
Sincerely,G. enhut, DirectorDivision of L'censing
Enclosure:
Revised Model Te hnicalSpecification rSnubberscc: w/enclosureI ENCLOSUREPLANT SYSTEMS3/4.7.9 SNBERSLIMITING CONDITION FOR OPERATION3.7.9 All snubbers shall be OPERABLE. The only snubbers excluded from thisrequirement are those installed on nonsafety-related systems and thenonly if their failure or failure of the system on which they are installed,would have no adverse effect on any safety-related system.APPLICABILITY: MODES 1, 2, 3 and 4 (MODES 5 and 6 for snubbers located insystems required OPERABLE in those MODES).ACTION:With one or more snubbers inoperable, witjiin 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> replace or restore theinoperable snubber(s) to OPERABLE status and perform an engineering evaluationper Specification 4.7.9.c on the supported component or declare the supportedsystem inoperable and follow the appropriate ACTION statement for that system.SURVEILLANCE REQUIREMENTS4.7.9 Each snubber shall be demonstrated OPERABLE by performance of thefollowing augmented inservice inspection program and the requirements ofSpecification 4.0.5.a. Visual InspectionsThe first inservice visual inspection of snubbers shall be performedafter four months but within 10 months of commencing POWER OPERATIONand shall include all snubbers. If less than two (2) snubbers arefound inoperable during the first inservice visual inspection, thesecond inservice visual inspection shall be performed 12 months +/- 25%from the date of the first inspection. Otherwise, subsequent visualinspections shall be performed in accordance with the followingschedule:No. Inoperable Snubbers Subsequent Visualper Inspection Period Inspection Period*#18 months +/- 25X1 12 months +/- 25%2 6 months +/- 25%3,4 124 days +/- 25%5,6,7 62 days +/- 25%8 or more 31 days +/- 25%The snubbers may be categorized into two groups: Those accessibleand those inaccessible during reactor operation. Each group may beinspected independently in accordance with the above schedule.*The inspection interval shall not be lengthened more than one step at a tine.#The provisions of Specification 4.0.2 are not applicable.3/4 7-22 PLANT SYSTEMSSURVEILLANCE REQUIREMENTS (Continued)b. Visual Inspection Acceptance CriteriaVisual inspections shall verify (1) that there are no visible indica-tions of damage or impaired OPERABILITY, (2) attachments to thefoundation or supporting structure are secure, and (3) in thoselocations where snubber movement can be manually induced withoutdisconnecting the snubber, that the snubber has freedom of movementand is not frozen up. Snubbers which appear inoperable as a resultof visual inspections may be determined OPERABLE for the purpose ofestablishing the next visual inspection interval, providing that(1) the cause of the rejection is clearly established and remediedfor that particular snubber and for other snubbers that may-begenerically susceptible; and (2) the affected snubber is functionallytested In the as found condition and determined OPERABLE per Specifi-cations 4.7.9.d or 4.7.9.e, as applicable. However, when the fluidport of a hydraulic snubber is found to be uncovered, the snubbershall be determined inoperable and cannot be determined OPERABLE viafunctional testing for the purpose of establishing the next visualinspection interval. All snubbers connected to an inoperable commonhydraulic fluid reservoir-shall be counted as inoperable snubbers.c. Functional TestsAt least once per 18 months during shutdown, a representative sample(10% of the total of each type of snubber in use in the plant shallbe functionally tested either in place or in a bench test. For eachsnubber that does not meet the functional test acceptance criteriaof Specification 4.7.9.d or 4.7.9.e, an additional 10% of that typeof snubber shall be functionally tested).or(that number of snubbers which follows the expression 35 [l + C]where c* is the allowable number of snubbers not meeting theThe value c will be arbitrarily chosen by the applicant and incorporated intothe expressions for the representative sample and for the resample prior tothe issuance of the Technical Specifications. The expressions are intendedfor use in plants with larger numbers of safety-related snubbers (>500) andprovide a confidence level of approximately 95% that 90% to 100% of thesnubbers in the plant will be OPERABLE within acceptable limits. That is,the confidence level will be provided no matter what value is chosen for c.It is advised, however, that discretion be used when initially choosing thevalue for c because the lower the value of c (the lower the amount ofsnubbers in the representative sample), the higher the amount of snubbersrequired in the re-sample will be. To illustrate: If c = 2 and 3 snubbersare found not to meet the functional test acceptance criteria, there will be70 snubbers in the representative sample and 31 snubbers required for testingin the re-sample; If c = 2 and 4 snubbers fail the functional test, therewill be 70 snubbers in the representative sample and 62 snubbers required fortesting in the re-sample; If c = 0 and 1 snubber fails the functional test,there will be 35 snubbers in the representative sample and 140 snubbersrequired for testing in the re-sample; If c = 0 and 2 snubbers fail thefunctions test, there will be 35 snubbers in the representative sample and280 snubbers required for testing in the re-sample.3/4 7-23 7i-.PLANT SYSTEMSSURVEILLANCE REQUIREMENTS (Continued)acceptance critetia selected by the operator, shall be functionallytested either in-place or in a bench test. For each number ofsnubbers above c which does not meet the functional test acceptancecriteria of Specifications 4.7.9.d. or 4.7.9.e, an additional sampleselected according to the expression 35 (1 + 2) (c 2 )2 (a -c)shall be functionally tested, where a is the total number of snubbersfound inoperable during the functional testing of the representativesample.Functional testing shall continue according to the expressionb [35(1 + 2) (c 2 )2 where b is the number of snubbers foundinoperable in the previous re-sample, until no additionalinoperable snubbers are found within a sample or until all snubbershave been -functionally tested}.The representative sample selected for functional testing shallinclude the various configurations, operating environments and therange of size and capacity of snubbers. At least 25% of the snubbersin the representative sample shall include snubbers from the followingthree categories:1. The first snubber away from each reactor vessel nozzle2. Snubbers within 5 feet of heavy equipment (valve, pump,turbine, motor, etc.)3. Snubbers within 10 feet of the discharge from a safetyrelief valveSnubbers that are especially difficult to remove or in high radiationzones during shutdown shall also be included in the representativesample.*In addition to the regular sample, snubbers which failed the previousfunctional test shall be retested during the next test period. If aspare snubber has been installed in place of a failed snubber, thenboth the failed snubber (if it is repaired and installed in anotherposition) and the spare snubber shall be retested. Test results ofthese snubbers may not be included for the re-sampling.Permanent or other exemptions from functional testing for individual snubbersin these categories may be granted by the Commission only if a justifiablebasis for exemption is presented and/or snubber life destructive testing wasperformed to qualify snubber operability for all design conditions at eitherthe completion of their fabrication or at a subsequent date.3/4 7-24 PLANT SYSTEMSBASES3/4.7.9 SNUBBERSSnubbers are provided to ensure that the structural integrity of the reactorcoolant system and all other safety related systems is maintained during andfollowing a seismic or other event initiating dynamic loads.The visual inspection frequency is based upon maintaining a constantlevel of snubber protection to systems. Therefore, the required inspectioninterval varies inversely with the observed snubber failures and is determinedby the number of inoperable snubbers found during an inspection. Inspectionsperformed before that interval has elapsed may be used as a new referencepoint to determine the next inspection. However, the results of such earlyinspections performed before the original required time interval has elapsed(nominal time less 25%) may not be used to lengthen the required inspectioninterval. Any inspection whose results require a shorter inspection intervalwill override the previous schedule;When the cause of the rejection of a snubber is clearly established andremedied for that snubber and for any other snubbers that may be genericallysusceptible, and verified by inservice functional testing, that snubber may beexempted from being counted as inoperable. Generically susceptible snubbersare those which are of a specific make or model and have the same designfeatures directly related to rejection of the snubber by visual inspection, orare similarly located or exposed to the same environmental conditions such astemperature, radiation, and vibration.When a snubber is found inoperable, an engineering evaluation isperformed, in addition to the determination of the snubber mode of failure, inorder to determine if any safety-related component or system has been adverslyaffected by the inoperability of the snubber. The engineering evaluationshall determine whether or not the snubber mode of failure has imparted asignificant effect or degradation on the supported component or system.To provide assurance of snubber functional reliability, a representativesample of the installed snubbers will be functionally tested during plantshutdowns at 18 month intervals. Selection of a representative sampleaccording to the expression 35 (1 + ') provides a confidence level ofapproximately 95% that 90% to 100% of the snubbers in the plant will beOPERABLE within acceptance limits.. Observed failures of these sample snubbersshall require functional testing of additional units.-Hydraulic snubbers and mechanical snubbers may each be treated as a differententity for the above surveillance programs.B 3/4 7-5 PLANT SYSTEMSBASESThe service life of a snubber is evaluated via manufacturer input andinformation through consideration of the snubber service conditions andassociated installation and maintenance records (newly installed snubber, sealreplaced, spring replaced, in high radiation area, in high temperature area,etc. ..). The requirement to monitor the snubber service life is included toensure that the snubbers periodically undergo a performance evaluation in viewof their age and operating conditions. These records will provide statisticalbases for future consideration of snubber service life. .The requirements forthe maintenance of records and the snubber service life review are notintended to affect plant operation.3/4.7.10 SEALED SOURCE CONTAMINATIONThe limitations on removable contamination for sources requiring leaktesting, including alpha emitters, is based on 10 CFR 70.39(c) limits forplutonium. This limitation will ensure that leakage from byproduct, source,and special nuclear material sources will not exceed allowable intake values.Sealed sources are classified into three groups according to their use,with surveillance requirements commensurate with the probability of damage toa source in.that group. Those sources which are frequently handled arerequired to be tested more often than those which are not. Sealed sourceswhich are continuously enclosed within a shielded mechanism (i.e. sealedsources within radiation monitoring or boron measuring devices) are consideredto be stored and need not be tested unless they are removed from the shieldmechanism.3/4.7.11 FIRE SUPPRESSION SYSTEMSThe OPERABILITY of the fire suppression systems ensures that adequatefire suppression capability is available to confine and extinguish firesoccurring in any portion of the facility where safety related equipment islocated. The fire suppression system consists of the water system, sprayand/or sprinklers, CO Halon, fire hose stations, and yard fire hydrants.The collective capability of the fire suppression systems is -adequate tominimize potential damage to safety related equipment and is a major elementin the facility fire protection program.In the event that portions of the fire suppression systems areinoperable, alternate backup fire fighting equipment is required to be madeavailable in the affected areas until the inoperable equipment is restored toservice. When the inoperable fire fighting equipment is intended for use as abackup means of fire suppression, a longer period of time is allowed toprovide an alternate means of fire fighting than if the inoperable, equipmentis the primary means of fire suppression.The surveillance requirements provide assurance that.the minimumOPERABILITY requirements of the fire suppression systems are met. Anallowance is made for ensuring a sufficient volume of Halon in the Halonstorage tanks by verifying either the weight or the level of the tanks. Levelmeasurements are made by either a U.L. or F.M. approved method.B 3/4 7-6 A:4I4'LANT SYSTEMSSURVEILLANCE REQUIREMENTS (Continued)If any snubber selected for functional testing either fails tolockup or fails to move, i.e., frozen in place, the cause will beevaluated and if caused by manufacturer or design deficiency allsnubbers of the same design subject to the same defect shall befunctionally tested. This testing requirement shall be independentof the requirements stated above for snubbers not meeting thefunctional test acceptance criteria.For the snubber(s) found inoperable, an engineering evaluation shallbe performed on the components which are supported by the snubber(s).The purpose of this engineering evaluation shall be to determine ifthe components supported by the snubber(s) were adversely affectedby the inoperability of the snubber(s) in order to ensure that thesupported component remains capable of meeting the designed service.d. Hydraulic Snubbers Functional Test Acceptance CriteriaThe hydraulic snubber functional test shall verify that:1. Activation (restraining action) is achieved within thespecified range of velocity or acceleration in both tension andcompression.2. Snubber bleed, or release rate, where required, is within thespecified range in compression or tension. For snubbersspecifically required to not displace under continuous load,the ability of the snubber to withstand load withoutdisplacement shall be verified.e. Mechanical Snubbers Functional Test Acceptance CriteriaThe mechanical snubber functional test shall verify that:1. The force that initiates free movement of the snubber rod ineither tension or compression is less than the specifiedmaximum drag force. Drag force shall not have increased morethan 50% since the last functional test.2. Activation (restraining action) is achieved within thespecified range of velocity or acceleration in both tension andcompression.3. Snubber release rate, where required, is within the specifiedrange in compression or tension. For snubbers specificallyrequired not to displace under continuous load, the ability ofthe snubber to withstand load without displacement shall beverified.! .3/4 7-25 PLANT SYSTEMSSURVEILLANCE REQUIREMENTS (Continued)f. Snubber Service Life MonitoringA record of the service life of each snubber, the date at which thedesignated service life commences and the installation and mainte-nance records on which the designated service life is based shallbe maintained as required by Specification 6.10.2.1.Concurrent with the first inservice visual inspection and at leastonce per 18 months thereafter, the installation and maintenancerecords for each snubber shall be reviewed to verify that theindicated service life has not been exceeded or will not beexceeded prior to the next scheduled snubber service life review.If the indicated service life will be exceeded prior to the nextscheduled snubber service life review, the snubber service lifeshall be reevaluated or the snubber shall be replaced or recon-ditioned so as to extend its service life beyond the date of thenext scheduled service life review. This reevaluation, replace-ment or reconditioning shall be indicated in the records.3/4 7-26 V4-I'.ADMINISTRATIVE CONTROLSe. Records of changes made to the procedures required by Specification6.8.1..f. Records of radioactive shipments.g. Records of sealed source and fission detector leak tests and results.h. Records of annual physical inventory of all sealed source materialof record.6.10.2 The following records shall be retained for the duration of the UnitOperating License:a. Records and drawing changes reflecting unit design modifications madeto systems and equipment described in the Final Safety Analysis Report.b. Records of new and irradiated fuel inventory, fuel transfers andassembly burnup histories.c. Records of radiation exposure for all individuals entering radiationcontrol areas.d. Records of gaseous and liquid radioactive material released to theenvirons.e. Records of transient or operational cycles for those unit componentsidentified in Table 5.7-1.f. Records of reactor tests and experiments.g. Records of training and qualification for current members of.theunit staff.h. Records of in-service inspections performed pursuant to these TechnicalSpecifications.i. Records of Quality Assurance activities required by the QA Manual.j. Records of reviews performed for changes made to procedures or equip-ment or reviews of tests and experiments pursuant to 10 CFR 50.59.k. Records of meetings of the (URG) and the (CNRAG).1. Records of the service lives of all hydraulic and mechanical snubbersincluding the date at which the service life commences and associatedinstallation and maintenance records.m. Records of secondary water sampling and water quality.6-17