NRC Generic Letter 1982-28

NRC Generic Letter 1982-028: Inadequate Core Cooling Instrumentation System

ML031210719
Person / Time
Issue date:	12/10/1982
From:	Eisenhut D G Office of Nuclear Reactor Regulation
To:
References
GL-82-028, NUDOCS 8212140103
Download: ML031210719 (11)

December 10, 1982TO: ALL LICENSEES OF OPERATING WESTINGHOUSE AND CE PWRs (EXCEPT ARKANSASNUCLEAR ONE -*I4 2- AND SAN ONOFRE UNITS 2 AND 3)SUBJECT: INADEQUATE CORE COOLING INSTRUMENTATION SYSTEM(GENERIC LETTER NO. 82-28)Gentlemen:On November 4, 1982, the Commission determined that an instrumentationsystem for detection of inadequate core cooling (ICC) consisting ofupgraded subcooling margin monitors, core-exit thermocouples, and areactor coolant inventory tracking system is required for the operationof pressurized water reactor facilities.On the basis of analysis of Information provided by licensees, meetingswith industry groups and independent studies by the NRC Staff, theCommission has found that during a small LOCA, there is a period of timebefore the core has boiled dry (indicated by core exit thermocouples)when the operators have insufficient information to clearly indicate avoid formation In the reactor vessel head or to track the inventory ofcoolant In the vessel and primary system. The Subcoollng Margin Monitorgives early indication of a problem but does not indicate whether thecondition is-getting worse or better.The addition of a reactor coolant inventory system will improve thereliability of plant operators in diagnosing the approach of ICC and inassessing the adequacy of responses taken to restore core cooling. Thebenefit will be preventive in nature in that the instrumentation willassist the operator in avoidance of ICC when voids in the reactorcoolant system and saturation conditions result from over coolingevents, steam generator tube ruptures, and small break loss of coolantevents. The addition of a reactor coolant inventory system, coupledwith upgraded in-core thermocouple Instruments and a subcoollng marginmonitor, provides an ICC instrumentation package which could significantlyreduce the likelihood of human misdiagnosis and errors for events suchas steam generator tube ruptures, loss of instrument bus or controlsystem upsets, pump seal failures, or overcooling events originatingfrom disturbances In the secondary coolant side of the plant. For lessfrequent events, involving coincidental multiple faults or more rapidlydeveloping small break LOCA conditions, the ICC could also reduce theprobability of human misdiagnosis and subsequent errors leading to ICC.8212140103 /OFFICEI > .... ................................ ........................ ......... ............. ......., ........................ ............................. ........ ................ ........................SURNAME~ .............0SURNME >....... .................... ............... ........................ ................ ........C ........................ .............. .......... ....... ................ -. ---DAT ........................ ......................... ........................ ........................ ........ ................ ........ ................ ........................NRC FORM 315 (10-80) NRCM 0240 O FFICIAL RECO RD C OPY USGPO: 1981-73a;CO, --, -- ---_ -...e ---, .-, -: .-. '. -. , -, -.- --

r of .;# a-2-The Nuclear Regulatory Commission has completed Its review of severalgeneric reactor level or Inventory system Instrumentation systems whichhave been proposed for the detection of ICC in PWRs. The CombustionEngineering Heated Junction Thermocouple (HJTC) system and the WestinghouseReactor Vessel Level Instrumentation System (RVLIS) are acceptable fortracking reactor coolant system inventory and provide an enhanced ICCinstrument package when used in conjunction with core exit thermocouplesystems and subcooling margin monitors designed in accordance with*NUREG-0737 and operated within approved Emergency Operating ProcedureGuidelines. The details of the NRC Staff review of these genericsystems are reported in NUREG/CR-2627 and NUREG/CR-2628 for the CombustionEngineering and Westinghouse systems, respectively.Other differential pressure (d/p) measurement techniques for reactorcoolant system inventory tracking are acceptable provided that they meetNUREG-0737 design requirements and monitor the coolant inventory overthe range from the vessel upper head to the bottom of the hot leg as aminimum.In order for the Commission to complete its review of your ICC system toassure that an acceptable system Is installed as soon as practicable,the NRC requires additional information.Accordingly, in order to determine whether your license should bemodified, you are required to submit to the Director, Division of Licensing,NRR, the following information in writing and under oath or affirmationpursuant to Section 182 of the Atomic Energy Act and 10 CFR 50.54(f) ofthe Commission's regulations.1. Within 90 days of the date of this letter, identify to the Director,Division of Licensing, the design for the reactor coolant inventorysystem selected and submit to the Director, Division of Licensing,detailed schedules for its engineering, procurement and installation.References to generic design descriptions and to prior submittalscontaining the required information, where applicable, are acceptable.2. Within 90 days of the date of this letter review the status ofconformance of all components of the ICC instrumentation system,including subcooling margin monitors, core-exit thermocouples, andthe reactor coolant inventory tracking system, with NUREG-0737,Item II.F.2 and submit a report on the status of such conformance.OFFICEO ...... ........................ ................................. ......................................... ........................ ............................. ........ ................ ........................ISURNAME > ........................ ................ ........ ................ ............ ........................ ......................................... ........................ ................ ................DATE t ............. ................ .............. ..............I.........----....-............... ................. ........................NRCFORM 318 (10-80) NRCM 0240 OFFICIAL RECORD COPY USG:M 1981-3S-90

W-f :77 F.-Uw r-wo-3-3. The installation of the ICC instrumentation system shall be completedduring the earliest refueling shutdown consistent with the existingstatus of the plant and practical design and procurement consider-ations. It has become apparent, through discussions with owners'groups and individual licensees, that schedules must adequately con-sider the integration of these requirements with other TMI relatedactivities. In recognition of this and the difficulty in implementinggeneric deadlines, the Comnission has adopted a plan to establishrealistic plant-specific schedules that take into account the uniqueaspects of the work at each plant. Each licensee is to develop andsubmit Its own plant-specific schedule which will be reviewed bythe assigned NRC Project Manager. The NRC Project Manager and licenseewill reach an agreement on the final schedule and in this manner pro-vide for prompt implementation of these important Improvements whileoptimizing the use of utility and NRC resources.Licensees who have completed installation of an approved generic ICCinstrumentation system are authorized to make their system operableprior to final NRC approval for purposes of operator training andfamiliarization. However, the ICC instrumentation system should not beturned on until the licensee has completed the task analysis portion ofthe control room design review, and should be used with prudence inrelation to any operator actions or decisions until the plant specificdesign and installation has been approved by the staff and instructionson its use and operation have been incorporated in accordance with theEmergency Operating Procedure Guidelines into approved emergency oper-ating procedures.For your convenience in performing the status review (Item 2) of yourconformance with NUREG-0737, a check list of the nine items of documen-tation cited on pp. II.F.2 -3 and 4 of that document is provided In anappendix to this letter. Even though you may have provided much of theinformation required for our review, we have not yet received all of theinformation required to complete our review of plant specific instal-lations for any licensee. In addition, some licensees have modifiedtheir positions during the period when NRC was re-reviewing the II.F.2requirements. Therefore, your status report should review for com-pleteness and reference those earlier submittals, including genericsubmittals, which remain valid in response to documentation items on thecheck list. In addition, you should include a proposed schedule for theremaining submittals. Information items to be addressed in the sub-mittal regarding your review of core exit thermocouples for conformanceto NUREG-0737, II.F.2, Attachnent 1, and your review of the ICC instru-mentation for conformance to NUREG-0737, Appendix B, are also listed inthe appendix to this letter. The staff review will focus on deviationstruzla UleUsr 19a criteria.OFFIC E ........................ ........................ ......... ............... ........................ ........................O........................ ........................SURNAME i ........................ ............... ......... ............... ............ ........................ ........................................ ........................ ............... .................DATE > ........................ ............... ......... ............... ............ ................. ............... ........................ ................................ ............... .................-RC FORM 318 (10-8) NRCM 024 OFF I CIA L R ECO RD CO PY SGP0: 1931_X$#

\._iK- /-4-This request for infon.^ation was approved by OMB under clearance number3150-0065 which expires May 31, 1983. Comments on burden and duplicationmay be directed to the Office of Management and Budget, Reports andManagement, Room 3208, New Executive Office Building, Washington, D.C.Sincerely,Darrell G. Eisenhut, DirectorDivision of LicensingEnclosure:As statedcc w/enclosureService ListsWestinghouse Electric Corp.Combustion Engineering.See previous concurrence page for concurrences:4- 4 ..mDL:ORB#5 D .:ORB#5 ORAB DL:ORB 5 OELD DL:AD:SA DL:AD:OR DL hOFFICE th ........ Jhee .......ppo Hto ...D~rute f4eld ..............r......Rtrala DE%4n-hut--SRNAMEt ..12/ ....82.... /.... ..... .. ......2 2.... 2... .. ...... ...82.. 1822.... ...... .... ..1 .... ....... ...........8. .......DATE .-I ....... ^.^.I.. ............ ._._ A A _ _ __............._.._...._._._ __ _ _NRC FORM 318 (10-8u^) NRCM 0240O FFICIA L R EC O RD C OPYUSGPO: 1981-335-960;

At, ~ " -a-5777-7,mg -&- *,-4 -This request for information was approved by OMB under clearance number31650-0065 which expires May 31, 1983. Comments on burden and dupitcationmay be directed to the Office of Management and Budget, Reports andManagement, Room 3208, New Executive Office Building, Washington, D.C.Sincerely,Darrell G. Eisenhut, DirectorDivision of LicensingEnclosure:As statedcc w/enclosureService ListsWestinghouse Electric Corp.Combustion Engineering, ., , I

APPENDIXChecklist.; .s... for Plant.Specific. Reviev of _Inadequate Core Cooling (ICC) Instrumentation SystemFor Docket Igo.Operated by:The following items for review are taken from NLJG-07379 p II.F.2-3, and 4. Responses should be made to 'full requiremexnts In IiURG-0737,not abbreviated forms below. Applicants'should provide reference toeither the applicant's submittal or the generic description under the* column labled "Ref erence.' These items are required to be reviewed on aplant specific basis by NUREG-0737 for all plants. Differences from thegeneric descriptions provided by Westinghouse, the Westinghouse Owner'saGroup, Combustion Engineering, or Combustion Engineering Owner's Groupmust be indicated by 'yes or no" inu the columu labled deviations andm ust,.'q. justified. Under the Column labeled schedule, either indicate.that yo'Eur documentation of the item is complete or provide a proposedschedule for your submittal.Reference Deviations Schedule -* .t1. Description of the proposed finalsystem including:a. a final design description ofadditional instrumentation anddisplays; o Ib. detailed description of existinginstrumentation systems.c. description of completed orplanned modifications.2. A design analysis and evaluation ofinventory trend instrumentation, andtest data to support design initem 1.3. Description of tests planned andresults of tests completed forevaluation, qualification, andcalibration of additional instru-mentation.-,- --.- .-77. 7 r 't' --T .-

-II7e4. Provide a table or descriptioncovering thi.evaluation of con-_..formance with NUREG-0737: 11.7.2,Attachment 1, and Appendix B (tobe reviewed on a plant specificbasis)*5. Describe computer, software anddisplay functions associated withICC monitoring in the plant.6. Provide a proposed schedule forinstallation, testing and cali-bration and implementation of anyproposed new instrumentation orInformation displays.7. Describe guidelines for use ofreactor coolant inventory trackingsystem, and analyses used to developprocedures.8. Operator instructions in emergencyoperating procedures for ICC andhow these procedures will bemodified when final monitoringsystem is implemented.9. Provide a schedule for additionaleLsvbmittals required**0:a .I*II.F.2 Attachment 1 (for Core Exit Thermocouples)In response to item 4 In the above checklist, the following materialsshould be included to show that the proposed system meets the design and.qualification criteria for the core exit thermocouple system.1. Provide diagram of core exit thermocouple locations or reference thegeneric description if appropriate.2. Provide a description of the primary operator displays including:a. A diagram of the display panel layout for the core cap and descrip-tion of how it is implemented, e.g., hardware or CRT display.b. Provide the range of the readouts.c. Describe the alarm system.d. Describe how the ICC instrumentation readouts are arranged withrespect to each other.3. Describe the Implementation of the backup displayCs) Cincluding thesubcooling margin monitors), how the thermocouples are selected, howthey are checked for operability, and the range of the display.4. Describe the use of the primary and backup displays. What trainingwill the operators have in using the core exit thermocouple instru-mentation? Row will the operator know when to use the core exitthermocouples and when not to use them? Reference appropriate -emergency.operating guidelines where applicable.

5. Confirm completion of control room design task analysis applicable toICC instrumentation. Confirm that the core exit .thermocouples meet thecriteria of NMREG-2737, Atta h lent 1 and Appendix Bo or identify adjustify devialions.6. Describe what parts of the systems are powered from the IE power sourcesused, and how isolation from non-lE equipment Is provided. Describe thepower supply for the primary display. Clearly delineate in two categorieswhich hardware is included up to the isolation device and wilch is not.7. Confirm the environmental qualification of the core exit thermocoupleinstrumentation up to the isolation device._ Appendix B (of NMXEG-0737, 11.7.2).Confirm explicitly the conformance to the Appendix B items listed below forthe ICC instrumentation, I.e., the SM., the reactor coolant inventory-.tracking system, the core exit thermocouples and the display systems.* Reference Deviations1. Environmental qualification2. Single failure analysis3. -Clss IE power source4. Availability prior to an accident5. Quality Assurance6. Continuous indications.7. Recording of instrument outputs8. Identification of instruments9. Isolation.,, ,' AI;I-- '-I *.'--"-et--' r'-,- '----- --v-; E---Ag --; ----., " .~ --,. " -. ..~'!~

I ..I-4 -**For the users of either Combustion 'Egineering:Eeated Junction Thermocouple(MNVC) System or .Wert ghoPeJDKfferential Pressure (dp) system a detailedresponse to the plant specific Items stated belowisihould be provided.-Reference DeviationsA. Westinghouse dp SystemI S-S1. Describe the effect of InstrumentuncertaInties on the measurementof level.2. Are the differential pressuretransducers located outsidecontainment?3. Are hydraulic isolators andsensors included in the Impulse-lines?B. CE EJTC System1. Discuss the spacing of thesensors from the core align-ment plate to the top of thereactor vessel head. H. Row wouldthe decrease In resolution dueto the loss of a single sensoraffect the ability of the systemto detect'an approach to ICC? .L._,...- I , I --:~ .. .I

Generic Letter 82-28Distribution:C FilesNRC PDRJShea (3)HSmithLPhillipsCBerlingerLRubensteinACRS (10)LUnderwood, IE(2)PWooleyNSICCHeltemes, AEODNRC RegionsResident InspectorsECaseGLainasFMiragliaTNovakPHungerbuhlerORB#5 ReadingLB BCsORB BCs__ , _ ; z ~~~~~. __ ....._..._.=a.

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