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ENCLCSURE 1

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Task Action Plan A-9

MEMCR;pCUM FOR: S. H. Hanauer.

FRCM: A. Thadani

SUBJECT: NRC-INCUSTRY AT.VS MEETING SUt*, MARY

The staff met with the PWR vendors, the* Atomic Industrial Forum (AIF) andseveral utility representatives to discuss the imcact of TMI-2 events onthe AT45 resolution plan dascribed in Volume 3 of NUREG-0460.

The staff made the following initial remarks:

1) ATdS is still a safety concern and protection frem these events must beprovided. Althougn plants need not be shutdcwn imediately because ofrelatively Icw likelihood of a severe ATWh in a PWR in the next coupleof years, ATd5 resolution with suitable speed is necessary to permit animplementation plan which would assure an acceptably Icw risk feca AT.4Sover the life of nuclear plants.

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2) The staff would like to receive industry views on the imoact of TMI-2on ATWS'and how to preceed frem now on to resolve ATdS. The staff notedthat they intend to propose an ATdS solution to the Cermission preferablywith but if necessary without the industry input.

3) In view of TMI-2 accident, the staff expressed the folicwing general cen-cerns with the Vol. 3 preposed resolution and asked for industry coments.

a) What assurance do we have that the excessi.e calcylated pressures forscac designs mcdified ::er Alternative #3 would not result in loss ofintegrity of reactor coolant pressure boundary. (Note - Scce designsmay experience peak pressures - 2000 psi).

b) Wculd increasing the nurrber of safety valves as per Alternative #4result in insufficient overall risk reductien? Would the priearysystem integrity be maintained? Would it be better to have larger -ca;acity valves? .

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c) In view of questions a anc b above, the pressurizer relief and safetyvalves must be qualified for water relief to assure that the no::les,the valve body and the support structure integrity will be maintainedand to estimate discharge ficw rate and the likelihood and effectsof valve chatter.

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d) In view of significant plant differences in the designs of auxiliaryfeedwater system, Emergency Core Cooling Systems and other systems,''how would the industry provide assurances that plant specificfeatures have been adecuately addressed in the "Farly Verification"approach for resolving ATWS as described in NUREG-0160, Vol . 3.

e) Other Lessons Learned from TMI-2

Following preliminary comments frem the NRC staff members, G. Sorensen ofWPPS who is also the Chairman of the AIF ATWS committee, made the folicwingcomments.

1) ATWS is not a safety issue but rather it is a licensing issue which needsresolution.

2) AIF in concert with the industry had reviewed ATWS in light of TMI-2 andhad coacluded that the Alternative 44 fix (mitigation) in Vol. 3 ofNUREG-0460 is not the correct solution to ATWS. The industry believesthat the alternative #2 fix (Prevention - Electrical Portion of RPS) ist.ye appropriate ATWS solution.,

3) Industry recognizes the TMI-2 impact on the role of the operator, histraining aids and other lessons learned frem this event. The industrybelieves that there is no need to rus.: to resolve ATWS because of thelow probability of ATWS and because some of the anticipated changes toplants as a result of TMI-2 accident review would direct resources toother issues.

Folicwing the AIF presentation, tne staff raised their cencerns that the ATWSresolution (not yet achieved) has been anything but hasty, that the NUREG dccu-ments on ATWS have been cut for sufficiently long time period, that protecticefrom ATWS is necessary, that TMI-2 event has raised concerns with the analysesassumptiens and therefore the staff needs industry technical assessment of theTMI-2 impact en ATWS. The staff suggested that tne TMI-2 event indicates aneed to answer at least the following specific questiens.

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1) Analyses indicate the sensitivity of peak pressure to AFWS design andactuation time for some plants.

Why should auxiliary feedwater actuation not be delayed beycnd technicalspecification values? What bases are available to assume AFWS actua-tien earlier than the technical specification value? How do the analysestake into censideration the limits on AFWS injection rate due to water- -hammer censiderations? How is the impact of ficw restrictors on scmeAFWS designs considered in the ATWS analyses? How are the significantplant specific features of AFWS treated in the analyses?

2) As in question 1 above hcw are the differences in ECCS designs evaluated?For example, for some ATWS events, the pressure and the pressurizer level

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remain high enough such that either the HPSI cannot be actuated (becauseof shut off head considerations) or the operator may fail to actuate HPSIbecause of insufficient available information.

3) Would single failure cause all PORVs to fail to open? If so, thenanalyses must be based on all PORVs failing to open. Further, several -plants are operating today with PORVs isolated. For these plants creditcannot be taken for relieving capability of these valves.

4) What assurance do we have that the ATWS events with a stuck open safetyvalve have been correctly analyzed? What is the potential for core un-covering under this scenario? What is the importance of ECCS actuation,reactor coolant pumps operation, and the pressurizer safety / relief valve*discharge model on the potential for uncovering of the core? Further,why shcold more valves not be assumed to stick open folicwing dischargeof subcooled water.

5) For laag Larm shutdown, discuss the following:

a) available equipment, instrumentation and their qualifica*.icn. (Mustconsider the effect of water discharged to the containment viaruptured quench tank).

b) impact of loss of offsite power

c) continued operation of reactor ccolant pumps. Also censider trippingof reactor ecoli.nt pumps.

d) Describe natural circulation, including effects of ncn-cendensables. ".Is reflux boiling mcde of operation anticipated? If so, justify.

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e) Would one anticipate Boron precipitation problem? Also considerTMI-2 type problems with possible letdown line plugging frcaBoron precipitation.

f) How are leakage problems from equipment outside containmentconsidered?

'' ' 6) Why should credit be given for operator action even after ten minutesfellowing an AT4S event initiation? TMI-2 experience does not provideencugh confidence in the ability of the operator to perfern correctacticns only in this short time period uncer high stress conditions.

In response to the staff concerns the industry made the folicwing coments.

AIF

1) -le industry is frustrated because the staff concerns imply considerationof multiple failures and small LOCA which are beycnd the credible eventsto be considered under AT45. (Note - safety valve stuck open (smallLOCA) is considered an anticipated transient). .

2) Industry would like to wait for approximately six months before consider-ing AT4S evaluations to minimize duplicale expenditures.

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1) W has s,ubmitted responses to the 2/15/79 Mattson letter.,

2) Calculated peak pressure of 2800 s 2900 psi (for Alt. #3) and proposedmodifications in turbine trip and auxiliary feedwater system actuation ,ci rcuitry.

3) EPRI expects to issue a request for proposal to conduct tests on PORVsand safety valves and some results should be available by end of CY 79.

4) Recocrended that "Early Verification" approach shculd be continued.

g - Ed Shearer speaking for himself

1) TMI raises few questions like the behavior of S/R valves and the cperatoraction. Further, prevention is better than mitigation and that mitigation " .would mean more and more analyses.

2) Continue with early verificaticr..

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1) Basically agrees with the staff concerns. Industry has longer list ofitems that could impact ATWS.

2) Stress analyses should be completed..~ ' '

3) Lik'elihood of additional failures beyond ATWS should be considered.

4) Prevention is better than mitigation.

B&W Owners Grouo

1) ATWS is not a safety problem.

2) Even if ATWS occurs, no significant risk to public health and safety.

3) TMI-2 suggests a desirability for realistic analyses. TMI-2 suggestsa need to assure that analyses bound the facilities.

4) Wait until " Lessons Learned" and " Bulletins and Orders" issues areresolved before pushing ahead with ATWS.

After the above industry comments, the staff made the following concluding,

remares.

1) We don't intend to go too fast on ATWS.

2) If Early Verification is to be pursued then there is a need to assure thatearlier ATWS analyses are correct and review the industry TMI-2 relatedlist. In this regard the industry was invited to meet with the staff todiscuss the technical issues which impact ATWS. The staff asked the indus-try to provide their assessment of TMI-2 impact on ATWS, the scope ofeffort to resolve these issues, and the schedule for performing this effortwithin 30 days.

3) We cannot wait another year to make progress in ATWS.

The list of attendees is in the enclosure../ : . . -- ./ __ --

A. Thadani

Enclosure:As stated

cc: See next page 1270 075.

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cc: Meeting AttendeesATWS DistributionPDRRSB FilesT. Speis

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ENCLOSURE

ATWS Meetine with Vendors & AIF

July 25, 1979

Ashok Thadani NRC/ DSSArthur McBride B&W

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Alan Hosler WPPSSSamir K. Sarkar FP&LAlan E. Ladieu YAECFred T. Stetson AIFRichard G. Rateick DECDAndrew J. Rushnok OECM. Srinivasan NRC/ DSSF. Akstulewicz NRC/DSEG. Sorensen WPPSS/AIFT. Speis NRC/ DSSF. C. Cherny NRC/ DSSJ. A. Norberg NRC/OSDStuart Thickman TVA - EN DESKarl 0. Layer BBRJ. Ted Enos AP&LTed Myers TEcoRobert Dieterick SMUDMichael J. Salerno CPCoS. Hardy Duerson B&W

' Bob Steither WGary Augustine ifP. M. Abraham Duke PowerMark Wisenburg USTVA - Office of PowerMichael Tokar NRC/ DSSPaul Scehnert NRC/ACRSDavid Bessette NRC/ACRSSteven Traisman Pacific Gas & ElectricSam Miranda WPat Loftus ~ 7Fred Mosby 7yle LaboratoryRoger Newton Wisconsin Electric PowerCraig Grochmal Stone & WebsterCharles A. Daverid Long Island Lighting Co.Robert L. Stright SNUPPSJoseph M. Weiss GEJoseph A. Gonyeau Ncrthern States Pcwer .

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Seth M. Coplan PiRC/DSEClayton L. Pittiglio tiRC/DSEKulin D. Desai f4RC/ DSSFuat Odar tiRC/ DSSKris Pare:ewski fiRC/DCRRoy Woods :iRC/DCRHarold Vander Molen F4RC/DCRGururejarao Rangarao PAS:1Y-Frank Mc? hatter B&WSteve Sanwartn BaWWilliam R. Murray Virginia Electric & Power Co.Sen Rodell VEPCDDon Swanson PGE Co.Paul V. Holton BechtelTornmy Errington Mississippi Power & LightRon Clausen Florida Power CorporationCharles B. Brinkman CEC. L. Kling CEWilliam Benjamin Cormonwealth Edison Co.Denny Kreps CEWilliam E. Burchill CEA. E. Scherer CERichard C. L. Olson Baltimore Gas & Electric Co.

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ENCLOSURE 2

Letter frem R. H. Bucholz (GE) to S. Hanauer, "AT45 Generic Analyses -Content of December 1979 Submittal", dated Sep ember 5,1979.

Letter from J. H. Taylor (B&W) to S. Hanauer, "B&W Comitments forATAS", dated September 13, 1979.

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Letter A. E. Scherer (CE) to S. Hanauer, "NRC Request for GenericATAS Infor .ation", dated August 31, 1979.

Letter L. O. DelGeorge (SWR 3 Cwners representative) to S. Hanauer,"ATWS BWR/3 Plants and 'lermorrt Yankee - Generic Analysis Supplement",dated August 28, 1979.

Letter T. M. Anderson (W) to S. Hanauer, "AT4S", dated August 24, 1979.

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