NRC Generic Letter 1991-13
rC>-UNITED STATESNUCLEAR REGULATORY COMMISSIONWASHINGTON, D. C. 20555September 19, 1991TO: LICENSEES AND APPLICANTS OF THE FOLLOWING PRESSURIZED-WATER REACTORNUCLEAR POWER PLANTS:1. Braidwood Units 1 and 22. Byron Units 1 and 23. Catawba Units 1 and 24. Comanche Peak Units 1 and 25. Cook Units 1 and 26. Diablo Canyon Units 1 and 27. McGuire Units 1 and 2
SUBJECT: REQUEST FOR INFORMATION RELATED TO THE RESOLUTION OF GENERIC ISSUE 130,*ESSENTIAL SERVICE WATER SYSTEM FAILURES AT MULTI-UNIT SITES," PURSUANTTO 10 CFR 50.54(f) -GENERIC LETTER 91-13DISCUSSIONThe purpose of this letter is to inform affected licensees and applicants ofthe technical findings resulting from the NRC resolution of Generic Issue 130(GI-130), "Essential Service Water System Failures at Multi-Unit Sites," and torequest information from licensees and applicants at affected multi-unit sitesrelating to the applicability of certain findings regarding their facilities.Affected licensees and applicants are required to respond to the request forinformation contained in this letter, but no new requirements or staff posi-tions are imposed on the affected licensees and applicants by this letter.The essential service water system (ESWS) is important in maintaining plantsafety during power operation, shutdown, and accident conditions. As part ofour evaluation of loss of essential service water (LOSW), extensive analyses ofthis issue were performed at the Brookhaven National Laboratory (BNL). Thetechnical findings of this effort at BNL are reported in NUREG/CR-5526,"Analysis of Risk Reduction Measures Applied to Shared Essential Service WaterSystems at Multi-Unit Sites.* In addition, the NRC staff performed aregulatory analysis to evaluate the safety benefits and implementation costsassociated with various equipment and the administrative-type improvements thatwere considered. The staff's regulatory analysis is contained in NUREG-1421,'Regulatory Analysis for the Resolution of Generic Issue 130: EssentialService Water System Failures at Multi-Unit Sites." These analyses assume thatthe flushing and flow testing provisions of Generic Letter (GL) 89-13, "ServiceWater System Problems Affecting Safety-Related Equipment," will be applied tothe crosstie lines as part of addressees' implementation of the resolution ofGI-51, 'Improving the Reliability of Open-Cycle Service Water Systems' (GL 89-13and Supplement 1). On the basis of results of these evaluations of this genericUIA-L)n ?I p -Generic Letter 91-13 September 19, 1991'.'...safety issue, the NRC staff has concluded that the following administrative-typeimprovements would significantly enhance the availability of the ESWS inaffected plants, and their implementation is warranted in view of the safetybenefit to be derived and the cost of implementation:o Technical specification (TS) changes contained.in Enclosure 1 to-enhancethe availability of the ESWS as applied to the design configuration ofaffected plants.o Improvement of emergency procedures for a LOSW using existing designfeatures, specifically: (a) operating and maintaining high-pressureinjection (HPI) pump integrity in the event of loss of reactor coolantpump (RCP) seals as a result of ESWS failure, and.(b) testing andmanipulating the ESWS crosstie between the units during a LOSW accident.The incorporation of technical specification improvements is consistent,with the.Commission's Policy Statement on Technical Specification Improvements.This policy statement captures existing requirements under Criterion 3(Mitigation of Design-Basis Accidents or Transients) or under the provisions toretain requirements that operating experience and probabilistic risk assessmentare shown to be important to the public health and safety. General DesignCriteria 44, 45, and 46 of 10 CFR Part 50, Appendix A, in conjunction with theprobabilistic risk, assessment performed under GI-130, form the technical basesfor these 1S and procedures improvements.A backfit analysis of the type described in 10 CFR 50.109(a)(3),and10 CFR 50.109(c) was performed, and a determination was made that these new TSand procedures improvements-would provide a substantial increase in.overall.protection of the public health and safety and that.-the costs of implementingthese improvements are justified in view of this increased protection.(Enclosure 2). It should be noted that for the benefits of these improvementsto be realized, the guidance contained.in GL 89-13 and Supplement 1 should-beconsidered in.the context of the inter-unit crosstie. Namely, GL 89-13 states::uRedundant and infrequently, used cooling loops should be flushed and flowtested periodically at the maximum design flow to ensure that they are notfouled or clogged. Other components in the service water system should betested on a regular schedule to ensure that they are not fouled or clogged...."Enclosure 3 contains a discussion of an additional safety enhancementidentified as part of our evaluation of GI-130 involving installation of adedicated RCP seal cooling system similar to that identified also under GI-23,NReactor Coolant Pump Seal Failures." The final decision on the possiblebackfitting of additional plant improvements has been deferred until completion fof GI-23; and that aspect of GI-130 is subsumed byGI-23. GI-23 will beresolved following the review of comments received based on the related FederalRe ister Notice published on April 19, 1991. The comment.period has beenextended until September 30, 1991. Enclosure 3 is provided to you for informa-tion only at this tim Generic Letter 91-13-3-September 19, 1991INFORMATION REQUEST (10-CFR 50.54(f))
Addressees
are requested to review the recommended TS and proceduresimprovements described in the preceding discussion and to evaluate theapplicability and safety significance of those improvements at their respectivefacilities. On the basis of results of the recommended plant-specificevaluations, each addressee shall provide a response to the NRC pursuant toSection 182 of the Atomic Energy Act and 10 CFR 50.54(f) which indicateswhether or not the recommended TS and procedures improvements are applicable toits facility, and whether or not the addressee will incorporate the TS(Enclosure 1) into its license and implement the procedures improvements. Theresponse shall be provided to the NRC under oath or affirmation within 180 daysof the date of this letter. If an addressee intends to implement therecommended TS and procedures improvements, the licensee shall include animplementation schedule as part of the response to this letter. The licenseeshould retain supporting documentation consistent with the records retentionprogram at each facility.An evaluation of the justification for this information request has beenprepared in accordance with the requirements of 10 CFR 50.54(f). Thatevaluation concludes that the information requested is Justified in viewof the potential safety significance of the ESW reliability issue to beaddressed with that information (Enclosure 4). Copies of NUREG-1421 andNUREG/CR-5526 are also enclosed for your information and to assist you inevaluating the applicability of this issue to your respective facilities(Enclosures 5 and 6).A list of recently issued NRC GLs is enclosed for your information (Enclosure 7).This request is covered by Office of Management and Budget Clearance Number3150-0011, which expires May 31, 1994. The estimated average burden hours is50 person hours per owner response, including assessment of the newrecommendations, searching data sources, gathering and analyzing the data, andpreparing the required letters. These estimated average burden hours pertainonly to the identified response-related matters and do not include the timefor actual implementation of the requested action. Send comments regardingthis burden estimate or any other aspect of this collection of information,including suggestions for reducing this burden, to the Information and RecordsManagement Branch (MNBB-7714), Division of Information Support Services,Office of Information Resources Management, U.S. Nuclear Regulatory Commission,Washington, D.C. 20555; and to Ronald Minsk, Office of Information andRegulatory Affairs (3150-0011), NEOB-3019, Office of Management and Budget,Washington, D.C. 2050 Generic Letter 91-13-4-September 19, 1991If you have any questions on this matter, please contact your Project Manager.
Sincerely,Jam s G. PartlowAss ciate Director for ProjectsOffice of Nuclear Reactor Regulation
Enclosures:
1. Draft TechnicalSpecifications (3/4.7.4)2. Backfit Analysis for GI-1303. Background Discussion ofa Deferred Safety Enhancementfrom GI-130 to GI-234. Justification Analysis[10 CFR 50.54(f)] for Generic5. NUREG-14216. NUREG/CR-55267. List of Recently Issued NRCGeneric LettersLetter on GI-130 ENCLOSURE IDRAFT TECHNICAL SPECIFICATIONPLANT SYSTEMS3/4.7.4 SERVICE WATER SYSTEMLIMITING CONDITION FOR OPERATION'3.7.4 At least two independent service water loops per unit and the crosstlebetween the service water systems of each unit (as applicable) shall beoperable. In addition, the crosstle shall be capable of being opened [from themain control room] as a flow path between the two units.APPLICABILITY: Modes 1, 2, 3, and 4.ACTION:A. Both units in Modes 1, 2, 3, or 4.1. With one service water loop per unit OPERABLE, restore at least twoloops per unit to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, or for the unitwith the inoperable service water loop, be in at least HOT STANDBYwithin the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30hours.2. With one [or both] of the crosstie valve(s) INOPERABLE and notcapable of being opened [from the control room], within 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />srestore the valve(s) to OPERABLE status or open the affectedvalve(s), and maintain the affected valve(s) open; otherwise be in atleast HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN withinthe following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.B. One unit in Modes 1, 2, 3,'or 4 and one unit in Mode 5 or 6.1. Verify that at least one pump in the shut down unit is OPERABLE and'available to provide service water to the operating unit. If neitherservice water pump in the shut down unit is OPERABLE, restore atleast 'one pump to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, or place theoperating unit'in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> 'and inCOLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />..2. With one'service water loop in the operating unit INOPERABLE, restoretwo loops in the operating unit to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> orbe in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLDSHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.::3.' With one [or both] of the crosstie valve(s) INOPERABLE and notcapable of being opened [from the control room], within 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />srestore the valve(s) to OPERABLE status or open the affectedvalve(s), and maintain the affected valve(s) open; otherwise be in atleast HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN withinthe following 30 hour3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> DRAFT TECHNICAL SPECIFICATIONSPLANT SYSTEMSSURVEILLANCE REQUIREMENTS4.7.4 Two service water loops per unit shall be demonstrated OPERABLE:a. At least once per 31 days by verifying that each valve (manual,power-operated, or automatic) servicing safety-related equipment thatis not locked, sealed, or otherwise secured in position is in itscorrect position.b. At least once per 92 days by cycling crosstie valves and/or verifyingthat valves are locked open with power removed; andc. At least once per 18 months during shutdown, by verifying that:1. Each automatic valve servicing safety-related equipment actuatesto its correct position on a test signal;2. Each service water system pump starts automatically on atest signal; and -3. Each crosstie valve is cycled or is locked open with powerremoved.BASES3/4.7.4 SERVICE WATER SYSTEMThe OPERABILITY of the service water system ensures that sufficient coolingcapacity is available for continued operation of safety-related equipmentduring normal and accident conditions. The redundant cooling capacity of thissystem, assuming a single failure, is consistent with the assumptions used inthe accident conditions within acceptable limits.In the event of a total loss of service water in one unit of a two-unit sitewhere backup cooling capacity is available via a crosstie between the twounits, the OPERABILITY of the unit crosstie along with a service water pump inthe shut down unit ensures the availability of sufficient redundant coolingcapacity for the operating unit. These limiting conditions will ensure asignificant risk reduction, as indicated by the analyses of a loss-of-servicewater system accident. The surveillance requirements ensure the short-term andlong-term operability of the service water system and the crosstie between thetwo units.' The service water system crosstle between the two units consists ofappropriate piping, valves, and instrumentation cross-connecting the dischargeof the service water pumps of the two units. By operating the crosstie, thesupply of additional redundant cooling capacity from one unit is available tothe service water'system of the other uni ENCLOSURE 2BACKFIT ANALYSIS (REFERENCE 10 CFR 50.109)FOR GENERIC ISSUE 130A.1 INTRODUCTIONThis enclosure presents'the backfit analysis for Generic Issue 130 (GI-130),"Essential Service Water System Failures at Multi-Unit Sites." The technicalfindings for GI-130 are presented in NUREG/CR-5526, and the regulatory analysisis presented in NUREG-1421. The studies apply to 14 reactor units at sevensites and indicate that essential service water system (ESWS) failures at theseplants are a significant'contributor to the overall plant risk. As aconsequence of these technical findings, and based on the cost/benefit analysesperformed, the staff has determined that these 14 plants may need to modifytechnical specifications (TS) to enhance the availability of the ESWS and toinstitute procedures to assure the integrity of the high-pressure injection(HPI) pump in the event of RCP seal failure as a result of loss of essentialservice water (LOSW), as well as procedures to test and manipulate the ESWScrosstie between the two units during a LOSW accident.The estimated benefit from the identified safety enhancements is a reduction inthe core damage frequency and a reduction in the associated risk of offsiteradioactive releases as a result of ESW failure. The reduction of risk to thepublic (per plant lifetime) is estimated to be 4141 person-rem (best estimatenumbers used) and supports the conclusion that these safety enhancementsprovide a substantial increase in the overall protection of the public healthand safety. Also, the direct and indirect costs of implementation arejustified in view of this increased protection.As discussed in NUREG-1421, when considered individually, most of thealternativeS analyzed for reducing the risk associated with this issue would becost-effective in meeting the $1000/person-rem guideline. The objective of theGI-130 resolution is that the risk from loss of the ESWS be reduced consistentwith the two basic requirements of the backfit rule that the correctivealternatives be both substantial and cost-effective.One of the potential improvements consisting of improvements in TS andemergency procedures was shown to be capable of reducing the core damagefrequency GCDF) from loss of ESW (1.5E-04/RY) by 17 percent (or byapproximately 3.OE-05/RY) in a cost-effective manner. The staff recognizes theuncertainties in these estimates, and in recognition of the potentiallysubstantial risk reductions (over 4000 person-rem per plant lifetime), thestaff believes that significant safety improvements can be achieved by low costchanges in TS and procedures. This is deemed to be consistent with theprovisions of the backfit rule.The overall approach to arriving at the proposed resolution considered both thenumerical results of the cost-benefit analysis and the spectrum and type ofpotential improvements available for potential risk reduction for
'_I-2loss-of-service-water sequences. Those alternatives that could reduce thenumber of occurrences of the LOSW initiators would be desirable from theprevention perspective. Those alternatives that would help to reduce theconsequences of an LOSW would be desirable from the mitigation perspective.The improvements in the TS would assist on the prevention side, while theimproved procedures would provide a blend of both prevention and mitigationcapabilities.The conclusion of this backfit analysis is that a substantial increase in theprotection of the public health and safety will be derived from backfitting ofthe ESWS improvements and that the backfit is justified in view of thefavorable cost/benefit ratios. In the following sections of this backfitanalysis, the nine factors stipulated by 10 CFR 50.109(c) to be used in thedetermination of backfitting are addressed.A.2 ANALYSIS OF 10 CFR 50.109(c) FACTORS FOR "ALTERNATIVE 5"A.2.1 ObjectiveThe objective of Alternative 5 (the proposed backfit) is to improve theperformance of the ESW system by providing a blend of both prevention andmitigation capabilities. This backfit will be applicable to all thepressurized-water reactor (PWR) plants (14 units) covered by GI-130.A.2.2 Licensee ActivitiesTo implement "Alternative 5," each licensee would modify TS in accordance withEnclosure 1 to this generic letter, as well as implement procedures foroperating and maintaining HPI pump integrity and testing and manipulating theESWS crosstie between units during a LOSW event.A.2.3 Public Risk ReductionBackfitting in accordance with the proposed alternative will yield a reductionin the incidence of public risk from the accidental offsite release ofradioactive materials of 4141 person-rem (best-estimate) per plant with anaverage remaining life of 30 years. This backfit will reduce the core damagefrequency from an LOSW by 17 percent (or by approximately 3.OE-05/RY).As detailed in Chapter 6 of NUREG-1421., the staff recognizes the uncertaintiesin these estimates and has considered both the numerical results of thecost-benefit analysis as well as the spectrum and type of potentialimprovements for risk reductions associated with LOSW sequences.A.2.4 Occupational ExposureThe radiological operational exposure is negligible and, therefore, theimplementation of Alternative 5 will not result in any increase in theradiological exposure to facility employee NI-3-A.2.5 Installation CostsThe best estimate total cost per reactor associated with Alternative 5 is$83,000. When the onsite averted costs are taken into account, thisalternative results in a net savings.A.2.6 Potential Safety ImpactA number of generic safety issues related to GI-130 have been in various stagesof resolution, including some that have already been resolved. The relation ofthese issues to GI-130 is as follows:o GI-23, "Reactor Coolant Pump Seal Failures" -- This generic safetyissue addresses the same possible improvements as Alternative 6 and,in part, Alternative 7 of GI-130. The staff's currentunderstandings, technical findings, and potential recommendationsregarding GI-23 were issued for public comment. On the basis of thestaff's current knowledge and perspective, the staff has identifiedan approach for the resolution of GI-23. This approach is containedin Draft Regulatory Guide DG-1008.An objective of the identified approach for the resolution of GI-23is to reduce the risk of severe accidents associated with RCP sealfailure by reducing the probability of seal failure, or todemonstrate that the risk is not significant, thus assuring that itis a relatively small contributor to total core damage frequency.The proposed means of doing so entails the installation of a separateand independent cooling system for the RCP seals. Hence,implementation of the proposed GI-23 resolution could provide asubstantial portion of the proposed GI-130 resolution. As such, theresolution of GI-130 is coordinated with the resolution of GI-23 byallowing the installation of a backup RCP seal cooling system to bedeferred to the resolution of GI-23 pending the receipt and review ofpublic comments. It is expected that information developed as aresult of the submittal of public comments will be helpful in ourefforts to better understand the performance of the RCP seals underloss of seal cooling conditions.o GI-51, "Improving the Reliability of Open-Cycle Service-WaterSystems" -- The resolution of this generic safety issue was reportedin August 1989 and its imposition began with the issuance of GenericLetter 89-13 and Supplement 1. Implementation of the 6I-51 entailsthe implementation of a series of surveillance, control, and testrequirements to ensure that the ESWS of all nuclear power plants arein compliance with all applicable licensing requirements.During the review of the operational experience data of GI-130,credit was taken for a corrective measure as a result of theresolution of GI-51 by excluding those events that involvedbiofouling of the ESW. Hence, GI-51 has no direct impact on GI-13 . -o GI-153, "Loss of Essential Service Water in LWRs" has been assignedNRC staff resources for its resolution. Its
Purpose
is to assessthis issue for all light-water reactors (LWRs) not already covered byGI-130." Insights"gained'by'the evaluation of GI-153 are expected tobe useful in confirming and/or supplementing the technical findingsof GI-130.Of interest to the decision process on this generic issue are the insights andreviews available in related probabilistic risk assessment (PRA) documentationin the open literature. 'The PRA work available in NUREG-1150, "Severe AccidentRisks: An Assessment for Five U.S. Nuclear Power Plants" (plus supportingdocumentation) is a source of extensive risk analyses information that might beused for an understanding of ESW vulnerabilities. An examination of theNUREG-1150 documentation of the three PWRs that were studied indicates that theanalyst thought that the ESW redundancy for two of the th'ree PWRs was largeenough that a complete' loss of ESW as an event initiator was deemed notcredible (eight pumps are available at'Sequoyah, Units 1 and 2). None of thefive plants in the NUREG-,150 study is a GI-130 plant; however, it isworthwhile to note that one of the PWR§s(Zion) identified the service watercontribution to CDF to be substantial (approximately 1.5E-04/RY). Thiscontribution for Zion was approximately 42 percent of the total core damagefrequency from all causes.Another PRA work'available in the'open literature is NSAC-148, "Service WaterSystems andNuclear Plant Safety," dated'May 1990. Although NSAC-148 is only acompilation of earlier PRA' results for six plants performed by the industry, itis useful to note 'that a greater appreciation of the service water system'scontribution to plant risk has moved the industry to initiate a program toimprove service water performance. The limited guidance available in NSAC-148is a step in the right direction. The wide range-of core damage frequencies(from LOSW)-at the 'isx plants studied suggests the large variability inplant-specific ESW configurations. The average CDF from LOSW for the sixplants was 6.55E-05/RY, with a range of 2.33E-04/RY-to-"negligible"contribution. Although'many details of these six PRAs are not included inNSAC-148, and'therefore,'must be considered to be used only with great caution,the overall message that the, service water' system provides an important safetyfunction that could be a substantial contributor to overall plant risk tendsto lend added credence to the GI-130 conclusions.A.2.7 NRC CostsImplementation of Alternative 5 's estimated at $21,000 (best estimate). Thisestimate assumes minimal resources for review of the generic letter responses.A.2.8 Facility Differences,Alternative 5 is applicable to all 14 plants covered by this study, regardlessof age or design. Other PWR and BWR plants that are not included under theresolution of GI-130 will be evaluated under GI-153, "Loss of Essential ServiceWater in LWRs."
-5 -A.2.9 Term of RequirementsThis represents the final resolution of GI-130. Alternative No. 6 entailingthe installation of an independent RCP seal cooling system has been subsumedunder the resolution of GI-2 ENCLOSURE 3
BACKGROUND
DISCUSSION OF A DEFERRED SAFETY ENHANCEMENTFROM GI-130 TO GI-23(INSTALLATION OF A DEDICATED RCP SEAL COOLING SYSTEM)As identified in NUREG-1421, "Regulatory Analysis for the Resolution of GenericIssue 130: Essential Service Water System Failures at Multi-Unit Sites," acombination of potential improvements consisting of the installation of abackup, dedicated RCP seal cooling system, and improvements in technicalspecifications (TS) and procedures are shown to be capable of substantial riskreduction. The specific features of such a backup, dedicated RCP seal coolingsystem would be as follows:o Single high pressure pump, 50-100 gpm capacityo Dedicated water storage tank with capacity to last at least 8-10hourso AC-independent (non-seismic) pumpo No support system cooling requiredo Once-through RCP seal heat removalLimited plant-specific information obtained through the existing literature(FSARs, and so forth), site visits, or discussions with licensees haveindicated that a number of the units covered by GI-130 already haveplant-unique features that could be responsive to this generic safetyenhancement. Rather than attempting to perform a series of PRAs tailored toeach of the 14 units, the NRC encourages each licensee or applicant to reviewthe plant-specific features (if any) that could be credited with departing fromthe generic (representative) base case plant configuration modelled inNUREG/CR-5526. In addition, other design alternatives may also be consideredutilizing arrangements different from that of the high-pressure pump sealinjection.One such alternative would provide flow through the RCP thermal barrier heatexchangers by connecting the fire water system into the component cooling water(CCW) lines. Most fire water systems have one diesel-driven fire water pump,which usually is independent of the ESWS.Generic Issue 23, "Reactor Coolant Pump Seal Failures," deals with thisrecommendation also, and specific guidance for resolving that generic issue isgiven in proposed Regulatory Guide DG-1008. While awaiting completion ofpublic review and comment on draft Regulatory Guide DG-1008, resolution of thisGI-130 item has been deferred until GI-23 is resolved. The reason for thisdeferral relates to the earlier development and promulgation of 10 CFR 50.63(station blackout rule), which was based on an assumption regarding themagnitude of RCP seal leakage during a station blackout event. While it was
--2 --left to GI-23 to validate that assumption, the resolution of GI-130 is alsobased on a RCP seal failure LOCA model very similar to that of GI-23, butdifferent from the leakage assumption in 10 CFR 50.6 ENCLOSURE 4JUSTIFICATION ANALYSIS [10 CFR 50.54(f)]FOR GENERIC LETTER ON GENERIC ISSUE 130Section 50.54(f) of 10 CFR Part 50 requires that "... the NRC must prepare thereason or reasons for each information request prior to issuance to ensure thatthe burden to be Imposed on respondents is justified in view of the potentialsafety significance of the issue to be addressed in the requested information."Further, Revision 4 of the Charter of the Committee To Review Generic Require-ments (CRGR), dated April 1989, specifies that, at a minimum, such anevaluation shall include the following:a. A problem statement that describes the need for the information interms of potential safety benefit,b. The licensee actions required and the cost to develop a response tothe information request, andc. An anticipated schedule for NRC use of the information.The staff's 10 CFR 50.54(f) evaluation of the information request addressingthe above elements follows:a. Problem Statement That Describes the Need for the Information inTerms o' Potential Safety BenetitThe recommended resolution of Generic Issue 130 (GI-130), "EssentialService Water System Failures at Multi-Unit Sites," applies to 14reactor units at seven sites and indicates that essential servicewater system (ESWS) failures at these plants may significantlycontribute to the overall plant risk. As a consequence of thesetechnical findings, and based on the cost/benefit analyses performed,the staff has determined that these 14 plants may need to modifytechnical specifications (TS) to enhance the availability of the ESWSand to institute procedures to assure the integrity of the HPI pumpin the event of RCP seal failure as a result of loss of essentialservice water (LOSW), as well as procedures to test and manipulatethe ESWS crosstie between the two units during a LOSW accident.The estimated benefit from the identified safety enhancements is areduction in the core damage frequency and a reduction in theassociated risk of offsite radioactive releases as a result of ESWfailure. The reduction of risk to the public (per plant lifetime) isestimated to be 4141 person-rem (best estimate numbers used) andsupports the conclusion that these safety enhancements provide asubstantial increase in the overall protection of the public healthand safety. Also, the direct and indirect costs of implementationare justified in view of this increased protection. The staffrecognizes the uncertainties in these estimates, and in recognitionof the potentially substantial risk reductions, the staff believesthat significant safety improvements can be achieved by low costchanges in TS and procedures, consistent with the provisions of thebackfit rul .-2-As discussed in NUREG-1421, when considered individually, most of thealternatives analyzed for reducing the risk associated with thisissue would be cost-effective in meeting the $1000/person-remguideline. The objective of the GI-130 resolution is that the riskfrom the loss of the ESWS be reduced consistent with the two basicrequirements of the backfit rule that the corrective alternatives beboth substantial and cost-effective.One of the potential improvements consisting of improvements in TSand emergency procedures was shown to be capable of reducing the CDFas a result of loss of ESW (1.5E-04/RY) by 17 percent (or byapproximately 3.OE-05/RY) in a cost-effective manner. As discussedearlier, this is deemed to be consistent with the provisions of thebackfit rule.The overall approach to arriving at the proposed resolutionconsidered both the numerical results of the cost-benefit analysis*and the spectrum and type of potential improvements available for-potential risk reduction for loss-of-service-water sequences. Thosealternatives that could reduce the number of occurrences of the LOSWinitiators would be desirable from the prevention perspective. Thosealternatives that would help to reduce the consequences of a LOSWwould be desirable from the mitigation perspective. The improvementsin the TS would assist on the prevention side, while the improvedprocedures would provide a blend of both prevention and mitigationcapabilities.The conclusion of our analysis is that a substantial increase in theprotection of the public health and safety will be derived from theimprovements in the TS and procedures, which are justified by thefavorable cost/benefit ratio. Hence, in view of the safetysignificance of the -recommended resolution of GI-130, the issuance ofthis generic letter under 10 CFR 50.54(f) is justified. (See alsoItem b. below.)b. The Licensee Response Required and the Cost to Develop the Responseto the information RequestAll the recipient licensees or applicants of this generic letterwould be requested to review the TS and procedures improvementsidentified as part of our evaluation of GI-130 and to assess theapplicability of these improvements to their respective facilities.We estimate that the cost of reviewing and evaluating the contents ofthis generic letter and preparing a response will cost no more than$2500 per licensee or applicant. It is expected.that this costmay
-3-vary from site to site, depending on the degree to which the TS andprocedures improvements apply to individual plants. This cost isinsignificant compared to the cost-justified improvements (see costestimates presented in NUREG-1421), which represent a substantialsafety improvement.c. An Anticipated Schedule for the NRC Use of the InformationWe expect that the responses to this generic letter would besubmitted within the 180-day schedule required by the generic letter,and that NRC staff review of the responses will be completed within180 days from their receip 'ENCLOSURE 7LIST OF RECENTLY ISSUED GENERIC LETTERSGeneric Date ofLetter No. Sub.[e ct Issuance Issued To91-1291-1191-1088-20SUPP. 49 1-0991-0891-0791-0691-05OPERATOR LICENSING NAT.EXAMINATION SCHEDULERESOLUTION OF GENERICISSUES 48, "LCOs FOR CLASS1E VITAL INSTRUMENT BUSES,"and 49, "INTERLOCKS AND LCOsFOR CLASS 1E TIE BREAKERS"PURSUANT TO 1OCFR50.54(f)EXPLOSIVES SEARCHES ATPROTECTED AREA PORTALS08/27/9107/18/9107/08/91INDIVIDUAL PLANT EXAMINATION 06/28/91OF EXTERNAL EVENTS (IPEEE)FOR SEVERE ACCIDENT VULNERA-BILITIES -10 CFR 50.54 (f)ALL PWR REACTORAND APPLICANTS FORAN OPERATING LICENSEALL HOLDERS OFOPERATING LICENSESTO ALL FUEL CYCLEFACILITY LICENSEESWHO POSSESS, USE,IMPORT OR EXPORTFORMULA QUANTITIESOF STRATEGIC SPECIALNUCLEAR MATERIALALL HOLDERS OFOLs AND CPs FORNUCLEAR POWERREACTORSALL HOLDERS OFOLs FOR BWRsALL HOLDERS OF OLsOR CPs FOR NUCLEARPOWER REACTORSALL POWER REACTORLICENSEES ANDHOLDERS OF CPsALL HOLDERS OF OLsALL HOLDERS OF OLsAND CPs FOR NUCLEARPOWER REACTORSMODIFICATION OF SURVEILLANCEINTERVAL FOR THE ELECTRICALPROTECTIVE ASSEMBLIES INPOWER SUPPLIES FOR THEREACTOR PROTECTION SYSTEMREMOVAL OF COMPONENT LISTSFROM TECHNICAL SPECIFICA-TIONSGI-23 "REACTOR COOLANTPUMP SEAL FAILURES" ANDITS POTENTIAL IMPACT ONSTATION BLACKOUTRESOLUTION OF GENERIC ISSUEA-30, "ADEQUACY OF SAFETY-RELATED DC POWER SUPPLIED,"PURSUANT TO 10 CFR 50.54(f)LICENSEE COMMERCIAL-GRADEPROCUREMENT AND DEDICATIONPROGRAMS06/27/9105/06/9105/02/ 9104/29/9104/09/91 Generic Letter 91-13-4September 19, 1991If you have any questions on this matter, please contact your Project Manager.
Sincerely,Original signed:James G. PartlowAssociate Director for ProjectsOffice of Nuclear Reactor Regulation
Enclosures:
1. Draft TechnicalSpecifications (3/4.7.4)2. Backfit Analysis for GI-3. Background Discussion ofa Deferred Safety Enhancfrom GI-130 to GI-234. Justification Analysis[10 CFR 50.54(f)] for Ge5. NUREG-14216. NUREG/CR-55267. List of Recently IssuedGeneric LettersReviewed by Barbara Calure,Letter on GI-130Technical Editor, on 7/12/91.DISTRIBUTIONCentral FilesNRC PDRPDIII-1 r/fMGamberoniOFCNAMEDATEOFCNAMEDATE:PE:PDIII-1:MGAMBERONIA/1: 8/6/DT:D:DSTl\: ADAANI: lygi/9: D: PDII# tYN :TMARSH: IC/ U/91(R,: ADT LI ./l6/91:TA:DRPWd(: ELEEDs~: C:t:CBERLINGER* : /91:TA:DRPE. a:MBOYLEtk'.1/1 /91:ADP:NRRlgJ-:JPARTLOW: 1 /1>/91Document Name: GI 130