ML16285A325
| ML16285A325 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 10/12/2016 |
| From: | Anderson M T NRC/NRR/DIRS/IPAB |
| To: | |
| Anderson M T,NRR/DIRS,301-415-8744 | |
| References | |
| Download: ML16285A325 (7) | |
Text
NEI99 02FAQ14 02FortCalhounMSPIPage1of5Revised09/8/2014Plant:FortCalhounNuclearStationDateofEvent:12/18/2013(ReactorCritical)SubmittalDate:05/14/2014LicenseeContact:ErickMatzkeTel/Email:402 533 6855ematzke@oppd.comNRCContact:LouisCruzTel/Email:301 415 3982louis.cruz@nrc.govPerformanceIndicator:MS06MitigatingSystemPerformanceIndex(EmergencyACPowerSystems)MS07MitigatingSystemPerformanceIndex(HighPressureInjectionSystems)MS08MitigatingSystemPerformanceIndex(HeatRemovalSystems)MS09MitigatingSystemPerformanceIndex(ResidualHeatRemovalSystems)MS10MitigatingSystemPerformanceIndex(CoolingWaterSystems)SiteSpecificFAQ(AppendixD)?YesFAQrequestedtobecomeeffective:Whenapproved.QuestionSectionNEI9902,Revision07,Guidanceneedinginterpretationand/oradditionalinformation:TheMSPISection(startingonpage32)doesnotprovideguidanceontheprocessinvolvedinreportingperformanceindicatordataforlicenseesthathavestartedupafterhavingbeeninashutdownconditionforanextendedperiodoftime.MSPIvaluesaresensitivetounavailabilityhourswhenthecriticalhoursforaunitarelow,asisthecasewithaplantstartingupafteranextendedshutdown.Inthis,MSPImaynotbeavalidindicationofperformanceandshouldbeconsiderednotvaliduntilsufficientcriticalhoursareaccrued.ThedraftNRCStaffWhitePaperonPerformanceIndicatorValidityduringExtendedShutdownandSubsequentStartup,lastdiscussedattheApril2014ROPWorkingGroupmeetingnotes:"Forplantsthatareinextendedshutdownconditions,theMSPIdataelementscontinuetobereported.Oncethelicenseeanticipatesthatashutdownwillenteranextendedperiod(sixmonths),aFAQshallbesubmittedfortheROPWorkingGrouptodetermineMSPIvalidity.ThelicenseeshallsubmitanadditionalFAQtoestablishMSPIvalidityuponsubsequentstartup."TimelineofsignificanteventsforFortCalhounStation:April,2011-FortCalhounNuclearStationshutdown:26RefuelingOutage.June6,2011-DeclaredaNotificationofUnusualEvent-RisingfloodwatersAugust29,2011ExitedNotificationofUnusualEvent-RiverLevel1003'6"andloweringJune7,2011-1B4ALoadCenterfireDecember,2011-FCSenteredInspectionManualChapter0350.December21,2013-Breakersclosedandextendedoutageended.
NEI99 02FAQ14 02FortCalhounMSPIPage2of5Revised09/8/2014NRCResidentCommentsResidentsInspectorhadnocomments.LicenseePositionFCSwillcontinuemonitoringMSPIandreportingdataelementsonaquarterlybasis.TheperformanceindicatorshallremainN/Auntilreporteddataisexpectedtobeamoreaccuratereflectionofcurrentplantperformance.
Thelackofcriticalhoursforthepast12quartershasandwillcontinuetoskewtheperformanceindicatorsvalidity.Ascriticalhoursareaccrued,performanceandpredictabilitybecomesincreasinglyrepresentativeofactualperformanceofthestation.AsoneofthebasicpremisesofMSPIisthatasinglefailureshouldnotresultinanadverseindicator,thefollowingcriteriawereusedbyFt.CalhounStationtodeterminewhentherewillbesufficientcriticalhourstoavoidafalsepositiveindicator:1. Thereshouldbeatleast4quartersofdatafollowingthestartupfromtheextendedoutage,and2. TheMSPIvalueshouldbeabletotoleratetheworsesinglefailureandunavailabilityequaltoafullLCOCompletiontimeandremainGreen( 1.0E 6/yr)followingstartupfromtheextendedoutage.AplantspecificPWROwnersGroup"What If"toolwasusedtopredictfutureMSPIvaluesusingexpectedplantdata(UnavailabilityandUnreliability).
ThechartsbelowillustratestheimpactfortheEACandRHRsystemsfromhavingafailureandassociatedunavailabilityinthe4 thquarter2014andtheimpactonMSPIasadditionalcriticalhoursareaccrued:
NEI99 02FAQ14 02FortCalhounMSPIPage3of5Revised09/8/2014EACQ12014Q22014Q32014Q42014Q12015MSPI 2.4E 082.7E 073.0E 071.2E 069.2E 07UAI 9.50E 092.86E 073.31E 077.11E 076.92E 07URI 1.49E 08 1.31E 08 3.18E 084.66E 072.32E 07%BaselineCritHrs9.7%18.7%27.8%35.6%45.8%Q12015MSPIdecreasereflectsaFeb2012failuredroppingoutofthe3yearmonitoringperiod.BothDG2YearOverhauls(103hourseach)areincludedin2014estimate.PastMSPIvaluesreflectoriginalestimateforobservedperiod.2.00E 070.00E+002.00E 074.00E 076.00E 078.00E 071.00E 061.20E 061.40E 06Q12014Q22014Q32014Q42014Q12015MSPI UAI URI AssumedFailureandappliedfullLCO EAC NEI99 02FAQ14 02FortCalhounMSPIPage4of5Revised09/8/2014RHRQ12014Q22014Q32014Q42014Q12015Q21015Q32015Q42015Q12016MSPI1.7E 07 1.5E 07 1.5E 071.9E 061.7E 061.4E 061.2E 061.1E 069.9E 07UAI1.92E 07 1.37E 07 1.37E 071.51E 061.35E 061.08E 068.93E 077.66E 076.60E 07URI 1.73E 08 1.05E 08 9.47E 093.52E 073.24E 073.24E 073.25E 073.18E 073.35E 07%BaselineCritHrs9.7%18.7%27.8%35.6%45.8%50.2%59.4%68.5%77.5%Estimatedplannedunavailabilityhoursforeachquarter:7hours.RFO27isscheduledfor45daysduringQ2_2015.2.00E 073.00E 078.00E 071.30E 061.80E 062.30E 06Q12014Q22014Q32014Q42014Q12015Q21015Q32015Q42015Q12016MSPI UAI URI AssumedFailure RHR NEI99 02FAQ14 02FortCalhounMSPIPage5of5 PotentiallyrelevantexistingFAQnumbers:NoneResponseSectionBasedontheresultsofthissensitivitystudy,thefollowingtableidentifieswheneachMSPIshouldbeconsideredvalid:MSPISystemEffectiveDateLimitingCriteriaMS06-EmergencyACPower1 stquarter2015SingleFailureplusassociatedunplannedunavailability(fullLCO)yieldswhiteindicatorin4 thquarter2014butgreenin1 stquarter2015MS07-HighPressureInjectionSystem4 thquarter20144quartersdataMS08-HeatRemovalSystem4 thquarter20144quartersdataMS09-ResidualHeatRemovalSystem1 stquarter2016SingleFailureplusassociatedunplannedunavailability(fullLCO)yieldswhiteindicatorin4 thquarter2015butgreenin1 stquarter2016MS10-CoolingWaterSystem4 thquarter20144quartersdataNRCResponse FAQ 14-02: FCS MSPI Validity NRC Response According to the "Simulation of MSPI Indicator Reaction to Plant in Long Term Shutdown and Initial Startup Page" white paper discussed in the ROP Working Group (The last documented version of this white paper is available through Agencywide Document Access and Management System (ADAMS) Accession No. ML13079A728
), the ROP Task Force recommended and the NRC staff agreed with the following:
ROP Task Force Recommendations The data from this study (Figure 1) shows that MSPI is very reactive when critical hours are low. This indicates that these situations should be treated on a case
-by-case basis. Fortunately, these situations have been uncommon over the life of the ROP, so that it is practical to consider a case
-by-case approach. As a starting point for these case
-by-case discussions, the ROP Task Force recommends the following decision rules for the display of MSPI on the NRC web page:
as been shut down for six months.
o On plant startup, if the calculated MSPI is greater than 1.0E
-6 (White) for the quarter prior to startup, MSPI will remain grayed out until 12 months of operation have accumulated after startup.
o On plant startup, if the calculated MSPI is less than or equal to 1.0E
-quarter prior to startup, MSPI will remain grayed out until there is a total of 12 months of operation in the 3
-year monitoring period.
onths of operation have accumulated
Given that FCS restarted on December 2013, the quarter prior to startup is 3Q
-2013. All MSPI values for FCS were green in 3Q
-2013. Therefore, the starting point in treating the validity of the MSPI indicators is that: MSPI will remain grayed out until there is a total of 12 months of operation in the 3-year monitoring period. For this particular case, 4Q-2014 represents the time
-frame at which a total of 12 months of operation have been accumulated
. In this FAQ, the licensee, FCS, proposes that the High Pressure Safety Injection (HPSI) system MSPI, Heat Removal System (HRS) MSPI, and Cooling Water System (CWS) MSPI become valid on the 4 th quarter of 2014. However, FCS proposes that the Emergency AC (EAC) power and Residual Heat Removal (RHR) system MSPI indicators become valid on the 1 st quarter of 2015 and 1 st quarter of 2016, respectively.
FCS predicted future MSPI values using a Pressurized Water Reactor Owners Group "What
-if" tool and expected plant data for unavailability and unreliability. These estimated MSPI values defined the licensee's proposal of the respective effective dates for each MSPI indicator to become valid. The NRC staff agrees with the proposal for the HPSI, HRS, and CWS MSPIs to become valid on 4Q2014, and for the EAC MSPI to become valid on 1Q2015. However, the NRC staff does not agree with the proposal for the RHR MSPI to become valid on 1Q2016.
The staff recognizes that the approach to maintain the RHR MSPI indicator invalid before 9 quarter s of operational data have been accrued proactively prevents the indicator from resulting in a false positive due to accrued unplanned unavailability. However, various factors such as increase in inspection resources, aggregation of various inputs to the indicator, alignment with previously established positions, and external stakeholder communications should also be taken into consideration when defining an effective date for the indicator to become valid.
Having the RHR MSPI invalid before 9 quarters of data have been accrued will increase inspection resources. While a baseline inspection approach would be applied to all other systems covered by MSPIs , additional inspection hours would have to be implemented to gain performance insights on the RHR system. Having the RHR MSPI invalid before 9 quarters of data have been accrued limits the indicator from providing insights on RHR performance based on the estimated outcome of accrued unplanned unavailability. It does not allow the indicator to provide insights on RHR performance that might result from any other failures and/or unavailability observed under this indicator.
The approach of having the RHR MSPI invalid before 9 quarters of data have been accrued results in a significantly different treatment from that used for the other MSPIs. It also diverges noticeably from the starting point for evaluation of such situation that was discussed through white papers in the ROP WG (ADAMS Accession No. ML13079A728), and the initial characterization of this FAQ. Such divergent approach can impact the overarching ROP goals of understandability and predictability.
Having the RHR MSPI invalid before 9 quarters of data have been accrued while all other MSPI indicators are treated as valid performance indicators can present communication challenges to external stakeholders. Such unique approach would impact the clarity of the performance indicator program.
Since historical data on RHR unplanned unavailability was not considered
, accounting for the Technical Specifications (TS)
Allowed Outage Time (AOT) (i.e., 7 days) could be a highly conservative estimate. If an indicator is really "invalid" for 9 of a total of 12 quarters (75%), what other types of implications can be inferred? Although TS SSCs in general make
-up the list of monitored components in MSPI, the AOTs, surveillance frequencies, etc. do not necessarily correlate with risk importance (i.e., maybe TS AOTs is not a good input to use for a risk
-based calculation).
The NRC staff concludes that: (1) the HPSI, HRS, and CWS MSPIs should become valid on 4Q2014, and (2) the EAC and RHR MSPIs should be rcome valid on 1Q2015.