ML20151N408

Summary of 880621 Meeting w/C-E & Intl Technology Corp in Rockville,Md Re Arsap Topic Papers Sets 1 & 2.Viewgraphs Encl

ML20151N408
Person / Time
Site:	05000470
Issue date:	07/28/1988
From:	Vissing G Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
PROJECT-675A NUDOCS 8808080208
Download: ML20151N408 (35)

Text

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!a nag'o,,~ UNITED STATES

.8 o NUCLEAR REGULATORY COMMISSION

$ $ WASHINGTON, D. C. 20555 July 28, 1988 k.....

Project No. 675 g -y1 d APPLICANT: Combustion Engineering, Inc.

FACILITY: CESSAR-DC, System 80+ Design l

SUMMARY

OF MEETING WITH COMBUSTION ENGINEERING /IT CORP.

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TO DISCUSS ARSAP TOPIC PAPERS SET NO. 1 AND SET NO. 2 INTRODUCTION t A meeting of the staff with representatives of Combustion Engineering (CE) and l International Technology (IT) Corporation was held i 3e NRC offices in l Rockville, Maryland, on June 21, 1988. The purpose ci ohe meeting was to I discuss the staff's comments on the ARSAP Topic Papers, Set No. 1, and to i

review and discuss the issues of ARSAP Topic Papers, Set No. 2. ARSAP Topic Papers, Set No. 2, were submitted by letters dated June C and 17, 1988.

l Enclosure 1 provides the list of attendees to the meeting. Enclosure 2 ,

provides the agenda for the meeting. Enclosure 3 provides the viewgraphs which IT Corporation used during their presentation. Enclosure 4 provides our Review Status Report on the ARSAP Topic Papers. This report identifies reviewers and tentative review schedules.

DISCUSSION I l

CE indicated that the development of ARSAP Topic Papers are closely l coordinated with the EPRI ALWR Requirements Document effort. The ARSAP Topic Papers are on the CESSAR-DC, System 80+ docket but are handled in a generic scene. However, there are no BWR issues involved in the ARSAP Topic Papers. l There was another concern about the concept of resolution. CE would want the resolution to be an agreement. For any particular issues, they would like an l agreement on the assumptions presented. If there could be no agreement, they

)

would like guidance on reaching an agreement. l n ,e was another concern about where the review effort to the ARSAP topic I j

ers fits in the priority scheme of hRR. The review of ARSAP topic papers  ;

e category 2 in a priority scheme of 4 of the review effort within NRR. '

It was noted that the topic papers do make reference to the use of the l industry's MAAP code. The staff is troubled by the use of the MAAP code since it has not been reviewed and accepted. The MAAP code is a changing code and the staff does not know in detail what is in the code. The industry response was to invite questions concerning the MAAP code where ever there was a concern in a particular application. The staff requested a brief summary of what the MAAP code is and what it will do.

The staff emphasized that the resolution of these issues should ultimately be in the designs. The designs should be such that the issues can be accommodated, 0f'(

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such that the issues will not be applicable or so conservative that the issues would be insignificant.

General comments on each of the topic papers of Set No. 1 follow:

1. Fission Product Release Prior to Vessel Failure - IDCOR Issue 1.

This issue was considered as to be resolved.

2. Reactor Coolant System Natural Circulation - IDCOR Issue 2.

The proposed resolution of this issue is through design for depressurization.

The staff considered depressurization to be acceptable provided it can be shown that it works. If the industry is dependent upon the MAAP code to justify the acceptance of the resolution, the staff could not accept _it. The NRC does not have the complete MAAP code. Also, from what is known about the MAAP code, the MAAP code does not have the capability to handle the dynamics of the transient. The staff suggested the use of NRC approved codes.

3. Release Model for Control Rod Materials - IDCOR Issue 3.

Since the agreed-upon resolution there has been new data. The staff must look at this new data.

4. Fission Product and Aerosol Deposition in RCS and Containment - IDCOR Issues 4 and 12.

l In order to continue our review on this issue, we need Reference 10, (P. G. E'ilison and M. Epstein, "Nuclear Fission Product Aerosol Transport and Deposition",

which is soon to be published).

5. In-vessel Steam Explosion and Alpha Mode of Containment Failure - IDCOR Issue 7.

The staff agrees that this issue is resolved.

6. Ex-vessel Fission Product Release - IDCOR Issue 9 and Ex-vessel Heat Transfer Models from Molten Core to Containment - IDCOR Issue 10.

This issue is not resolved within NRC or the industry. The staff has no difficulty with the proposed model. The problem is in the great uncertainties of the inputs. There is no agreement on what happens when the core hits the concrete. The importance of concrete was not adequately flagged in the early days. The fission product release, flow rate and coolability must be analyzed. Heat Transfer models vary by a factor of 5 to 6.

7. Revaporization of Fission Products - IDCOR Issue 11.

Indicate the method of analysis to be used and provide more detail concerning the analysis.

4

8. Modeling of Emergency Response - IDCOR Issue la The staff agrees with the industry resolution.

9. Secondary Containment Performance - IDCOR Issue 16.

For the application of resolution of this issue to the System 80+ design provide the following information:

A. Provide qualifications of ARSAP relevant to NRC reliance on ARSAP evaluation and conclusion that the NRC/IDCOR issue identified is valid for ALWRs.

B. Provide the basis and rational for the ARSAP conclusions.

C. Provide the basis and rational for the CE conclusions regarding the applicability of the identified NRC/IDCOR resolution to the System 80+ design.

D. Describe the extent and depth of the CESSAR 80+ system commitment to the NRC/IDCOR resolution, including the scope of applicability among the System 80+ safety systems.

l IT Ccrporation presented the ARSAP Topic Papers, Set No. 2, as provided in '

Enclosure 3. For IDCOR Issue 5, In-Vessel Hydrogen Generation, the staff indicated that the industry interpretation of the modeling of the PBF-SFD experiment design is not acceptable to the staff. The NRC does not confirm that the maximum hydrogen produced is that produced by 75% of the active core zirconium oxidizing. Experiments to date do not confirm this. For IDCOR Issue 8, Direct Containment Heating, the staff indicated that we will have significant comments. For IDCOR Issue 17, Hydrogen Ignition and Burning, the  !

staff indicated that recent data indicates that the minimum hydrogen concentration of 13% by volume for detonation may not be proper. The data, <

Enclosure 5, indicates that the minimum concentration for hydrogen detonation {

should be 9.5% by volume at higher temperatures. For containment design, the j lower minimum concentration would be more applicable, j CE suggested that we have meetings like this meeting for each submittal of topic papers. It is CE's goal to submit topic papers for staff review at monthly intervals until all topic papers are submitted. The staff's goal is to provide draft SERs or letters of agreement, as appropriate, according to the schedule of Enclosure 4.

. Vissing, Pr ct Manager Standardization and Non-Power Reactor Project Directorate Division of Reactor Projects - III, IV, V and Special Projects

Enclosure:

As stated

July 28, 1988

8. Modeling of Emergency Response - IDCOR Issue 14 The staff agrees with the industry resolution.

9. Secondary Containment Performance - IDCOR Issue 16.

For the application of resolution of this issue tc the System 80+ design provide the following information:

A. Provide qualifications of ARSAP relevant to NRC reliance on ARSAP evaluation and conclusion that the NRC/IDCOR issue identified is valid for ALWRs.

B. Provide the basis and rational for the ARSAP conclusions.

C. Provide the basis and rational for the CE conclusions regarding tha applicability of the identified NRC/IDCOR resolution to the System 80+ design.

D. Describe the extent and depth of the CESSAR 80+ system commitment to the NRC/IDCOR resolution, including the scope of applicability among the System 80+ safety systems.

IT Corporation presented the ARSAP Topic Papers, Set No. 2, as provided in Enclosure 3. For IDCOR Issue 5, In-Vessel Hydrogen Generation, the staff indicated that the industry interpretation of the modeling of the PBF-SFD experiment design is not acceptable to the staff. The NRC does not confirm that the maximum hydrogen produced is that produced by 75% of the active core zirconium oxidizing. Experiments to date do not confirm this. For IDCOR Issue 8, Direct Containment Heating, the staff indicated that we will have significant comments. For IDCOR Issue 17, Hydrogen Ignition and Burning, the staff indicated that recent data indicates that the minimum hydrogen concentration of 13% by volume for detonation may not be proper. The data, Enclosure 5, indicates that the minimum concentration for hydrogen detonation should be 9.5% by volume at higher temperatures. For containment design, the lower minimum concentration would be more applicable.

CE suggested that we have meetings like this meeting for each submittal of topic papers. It is CE's goal to submit topic papers for staff review at monthly intervals until all topic papers are submitted. The staff's goal is to provide draft SERs or letters of agreement, as appropriate, according to the schedule of Enclosure 4.

original signed by Guy S. Vissing, Project Manager Standardization and Non-Power Reactor Project Directorate Division of Reactor Projects - III, IV, V and Special Projects

Enclosure:

As stated w

CIA PN AD:PDSNP EKy on issing:cw CMiller 07/ /88 07 2 /788 07//f/88

Enclosure 1 C. E. SYSTEMS 80+

MEETING - JUNE 21, 1988 NAME ORGANIZATION PHONE NO.

Charles Ferrell SAIB/RES/NRC 301-492-3978 Tony Buhl IT Corp /ARSAP 615-481-3300 Stephen Additon IT Corp /ARSAP 202-463-0550 P.obert E. Henry FAI/ARSAP 312-323-8750 Bob Capp EG&G Idaho /ARSAP 208-526-1715 Chang Park BNL FTS 666-2788 John Lehner BNL 516-282-3921 Len Soffer NRC/RES 301-492-3916 Robert J. Hammersley FAI/ARSAP- 312-323-8750 George A. Davis Conibustion Engineering 203-285-5207 Stan Ritterbusch Combustion Engineering 203-285-5206 Mario Fontana IT/ARSAP 615-481-3300 Guy S. Vissing NRR/PDSNP 301-492-1101 Thomas J. Walker RES/AEB 301-492-3908 James T. Han NRC/RES/AEB 301-492-3939 Brad Burson NRC/RES/AEB 301-492-3909 )

J. H. Raval NRR/SPLB 301-492-0857 i E. S. Chelliah RES/PRAB 301-492-3948 l R. Van Houten NRC/RES/AEB 301-492-3936 ;

R. W. Houston NRC/RES/DRAA 301-492-3900 i Mark W. Crump Combustion Engineering 203-285-4537 l Brad Hardin NRC/RES/DRA 301-492-3733 Pat Worthington NRC/RES/AEB 301-492-3911 Bob Uright NRC/RES/AEB 301-492-3906 ,

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Enclosure 2 -

HRC/C-E/ARSAP MEETING ON SEVERE ACCIDENT ISSUES TOPIC SETS 1 AND 2 White Flint, Md (Nicholson Lane South, Room 14)

June 21, 1988 10:00 Introduction S. E. Ritterbusch 10:05 Review of NRC Questions and G. S. Vissing Comments on Topic Set 1 0 Fission Product Release NRC Staff 0 Release of Control Rod Material 0 In-Vessel Steam Explosion 0 Ex-Vessel Heat Transfer o Emergency Responses o Secondary Containment 0 RCS Natural Circulation 0 Fission Product Release o Revaporization 11:30 Lunch

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12:00 Summary-of Topic Set 2 ARSAP l 1

o Hydrogen Generotten o Core Melt Progression o Containment Heating o Containment Performance o Hydrogen Ignition o Debris Coolability 1:30 Summary of Program for Submitt01 of ARSAP Remaining Topic Sets 1:45 Summary of Program for Reviews of NRC Staff Remaining Topic Sets 2:00 Closing S, E. Ritterbusch l

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Enclosure 3

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.A) RC- k2 S AP MT&. Ot/NE 31,1964 M. HA n na 3Lt7

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l 2.1 IN-VESSEL HYDROGEN GENERATION flDCOR ISSUE l I

5) ISSUE DEFINITION i CONTAINMENT PRESSURIZATION FROM HYDROGEN l COMBUSTION IS A MAJOR CONCERN IN SEVERE ACCIDENT RISK ASSESSMENT l l

o CONTAINMENT IS DESIGNED FOR DESIGN BASIS EVENTS, BUT EVALUATED FOR MARGINS TO FAILURE UNDER SEVERE ACCIDENT CONDITIONS l

o MELT PROGRESSION PHENOMENA GOVERN THE AMOUNT 1

OF HYDROGEN GENERATED o THE CONTAINMENT FREE VOLUME AND THE AMOUNT l

OF HYDROGEN GENERATED AS WELL AS THE MASS OF STEAM IN THE ATMOSPHERE GOVERN BOTH THE f POTENTIAL FOR DEFLAGRATION OR DETONATION I AND THE CAPABILITY TO TOLERATE COMBUSTION

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2.1 IN-VESSEL HYDROGEN GENERATION HISTORIC, PERSPECTIVE flDCOR) 1 IDCOR EFFORTS FOCUSED ON THE DEVELOPMENT OF MAAP MODELS, BENCHMARKED AGAINST HYDROGEN GENERATION EXPERIMENTS PROTOTYPlc OF REACTOR CONDITIONS i

o PRINCIPAL BENCHMARKS ARE LOFT LP-FP-2 ' AND TMI-2: BOTH ARE CONSISTENT WITH A l l

DECREASING POTENTIAL FOR OXIDATION DUE TO RELOCATED MATERIAL o PBF-SFD HAS ALSO BEEN MODELLED, THOUGH THE v

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EXPERIMENT DESIGN APPEARS TO PRECLUDE THE INFLUENCE OF RELOCATED MATERIAL EXPECTED FOR REACTOR CONDITIONS ,

o INITIAL TMI-2 ANALYSES USED MAAP 2.0, BUT  ;

UPDATED ANALYSES WITH MAAP 3.0B ARE CURRENTLY UNDERWAY D 'j o ALL OF THE ABOVE CONFIRM MAXIMUM HYDROGEN GENERATION BELOW AN AMOUNT EQUIVALENT TO /WT"

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THAT PRODUCED BY 75% OF THE ACTIVE CORE ZlRCONIUM OXIDIZING

l 2.1 IN-VESSEL HYDROGEN GENERATION P iTORICAL P_ERSPECTIVE INRC)

NRC HAS CONDUCTED MAJOR EXPERIMENTS AND ANALYTICAL PROGRAMS TO ADDRESS THIS ISSUE o EXPERIMENTS 1. CLUDE PBF-SFD, ACRR, NRU, AND LOFT-FP-2 o ANALYSES HAVE BEEN PERFORMED WITH MARCH 2.0, MARCH 3.0 IN THE SOURCE TERM CODE PACKAGE, SCDAP, AND MELPROG o ONE SENSITIVITY STUDY DEMONSTRATED TWICE THE AMOUNT OF HYDROGEN GENERATED (l.E. 60%

EQUIVALENT VS. 31%) WITH MELT RELOCATION DELAYED TO 2500 K FROM 2200 K o THE NRC POSITION, BASED ON UNCERTAINTIES IN THE MELT PROGRESSION PHENOMENA, WAS THAT A RANGE OF HYDROGEN PRODUCTION ESTIMATES, EXTENDING TO AMOUNTS SIGNIFICANTLY GREATER '

THAN PREDICTED BY MAAP, SHOULD BE CONSIDERED IN BOUNDING SEVERE ACCIDENT RISK

2.1 IN-VESSEL HYDROGEN GENERATION APPROACH TO RESOLUTION

1. ENSURE THAT THE CONTAINMENT IS DESIGNED TO WITHSTAND A BURN OF HYDROGEN IN THE AMOUNT l PRODUCED BY OXIDATION OF 75% OF THE ZlRCONIUM CLADDING IN THE ACTIVE CORE (EPRI REQUIREMENTS DOCUMENT)

2. PROVIDE TECHNICAL JUSTIFICATION THAT THE AMOUNT OF HYDROGEN GENERATED BY OXIDATION OF 75% OF THE ZlRCONIUM CLADDING IN THE ACTIVE CORE IS A SUITABLE UPPER BOUND FOR THE ADVANCED PWR CONTAINMENT CAPABILITY o ADDRESS THE CURRENT LICENSING BASIS o ADDRESS THE AVAILABLE EXPERIMENTAL DATA, INCLUDING NRC TESTS o ADDRESS THE RESULTS OF ANALYSES WITH NRC CODES o PERFORM MAAP ANALYSES, WITH AND WITHOUT 1 THE INFLUENCE OF CORE DEFORMATION, USING UPDATED MODELS BELOW J

B

2.1 IN-VESSEL HYDROGEN GENERATION APPROACH TO RESOLUTION (CONTINUED)

3. IMPLEMENT MAAP IMPROVEMENTS TO MODEL MOLTEN ZlRr 'lOY-FUEL EUTECTIC FORMATION, REI .ATION, AND REFREEZING; INCLUDE THE '

EFF .TS OF RELOCATED MASS ACCUMULATION ON COOLANT CHANNEL GEOMETRY l

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2.2 CORE MELT PROGRESSION AND VESSEL FAILURE (IDCOR ISSUE 6) ISSUE DEFINITION COMPLEX CORE MELT PROGRESSION PHENOMENA DETERMINE THE STATE OF THE REACTOR IN A SEVERE ACCIDENT, THE STATE OF CORE DEBRIS AT VESSEL FAILURE, EARLY CHALLENGES TO CONTAINMENT INTEGRITY, AND THE STATE OF MANY FISSION PRODUCTS i

o UNCERTAIN PHENOMENA INCLUDE RELOCATION OF MOLTEN MATERIAL (BOTH THRESHOLD AND MECHANISMS), CRUST AND RUBBLE BFD FORMATIONS, THERMAL ATTACK ON STRUCTURES AND DEBRIS, DEBRIS-COOLANT INTERACTIONS IN THE LOWER PLENUM, AND REACTOR' VESSEL FAILURE o THE REACTOR VESSEL FAILURE MODE (INCLUDING TIMING, LOCATION, SIZE AND PRESSURE) AND THE CORRESPONDING COMPOSITION, AMOUNT, AND TEMPERATURE OF RELEASED CORE DEBRIS l

DETERMINE CONTAINMENT CHALLENGES THROUGH DIRECT CONTAINMENT HEATING (TOPIC 2.3), l OXIDATION OF RELEASED MATERIALS, THE l l

INITIATION OF CORE-CONCRETE INTERACTIONS, AND THE RELATED COOLABILITY OF THE DEBRIS (TOPIC 2.6)

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2.2 CORE MELT PROGRESSION AND VESSEL FAILURE HISTORICAL PERSPECTIVE IDCOR DEVELOPED CORE MELT PROGRESSION MODELS IN MAAP 3.0, INCLUDING:

o CANDLE-LIKE RELOCATION OF MOLTEN MATERIAL AND FORMATION OF BLOCKAGE o ACCUMULATION OF MOLTEN MATERIAL TRIGGERING SUDDEN LOWER PLENUM ENTRY AND THERMAL ATTACK ON THE VESSEL LOWER HEAD t o WELD FAILURE, INSTRUMENT TUBE EXPULSION (AT HIGH PRESSURE), STEEL ABLATION, AND COMPLETE BLOWDOWN WITHIN 4-80 SECONDS NRC APPROACHES INVOLVED DIFFERENCES o THE NRC POSITION WAS THAT RELEASES OF LARGER AMOUNTS OF DEBRIS (THAN IDCOR PREDICTED) '

WITH VARYING STEEL COMPOSITION SHOULD BE TREATED PARAMETRICALLY IN SEVERE ACCIDENT ANALYSES l

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2.2 CORE MELT PROGRESSION AND VESSEL FAILURE APPROACH TO RESOLUTION l

1. DEVELOP MORE MECHANISTIC MAAP MELT PROGRESSION MODELS INCLUDING EUTECTIC FORMATION, A THRESHOLD BREAKOUT TEMPERATURE, EUTECTIC FLOW AND HEAT TRANSFER, MOLTEN CORE DEBRIS BEHAVIOR, AND ATTACK ON THE LOWER CRUST

2. PERFORM SENSITIVITY STUDIES OF DEBRIS BEHAVIOR IN THE LOWER PLENUM WITH AN OPERATIONAL SAFETY DEPRESSURIZATION SYSTEM -

1 TO CONFIRM DEPRESSURIZATION PRIOR TO VESSEL FAILURE AT A PENETRATION

3. PERFORM SENSITIVITY STUDIES OF IMPORTANT PARAMETERS IN THE NEW MODELS TO CONFlRM THAT CORE MELT PROGRESSION UNCERTAINTIES DO l NOT SIGNIFICANTLY AFFECT THE SEVERE l ACCIDENT PERFORMANCE OF AN ALWR CONTAINMENT k )

l 2.3 DIRECT CONTAINMENT HEATING flDCOR ISSUE 8)

ISSUE DEFINITION i

POTENTIAL FOR CONTAINMENT PRESSURIZATION l FOLLOWING HIGH PRESSURE DISCHARGE OF FINELY FRAGMENTED CORE DEBRIS FROM THE REACTOR VESSEL DUE TO:

o RAP'. ) HEAT TRANSFER FROM DEBRIS TO ATMOSPHERE o OXIDATION OF UNREACTED METALLIC MATERIALS PRODUCING HYDROGEN AND ADDITIONAL HEATING o POTENTIAL HYDROGEN COMBUSTION

> o RAPID STEAM GENERATION FROM WATER IN CAVITY AIDING TRANSPORT OF CORE DEBRIS, HYDROGEN, AND ENERGY TO THE UPPER CONTAINMENT VOLUME i

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2.3 DIRECT CONTAINMENT HEATING HISTORICAL P_ERSPECTIVE ,

I IDCOR CONCLUDED THAT MOST CURRENT PWR CAVITY I CONFIGURATIONS MAKE DCH CONTRIBUTION TO CONTAINMENT PRESSURIZATION SMALL ,

o CAVITY GEOMETRY AND ASSOCIATED STRUCTURES ARE SIGNIFICANT o "BUILDING BLOCK" SIMULANT MATERIAL TESTS DEMONSTRATED RETENTION EFFECTS o BOUNDING ANALYSES FOR SEVEN METRIC TONS OF DEBRIS INTO CONTAINMENT WERE ACCEPTABLE FOR LARGE DRY PWR DESIGN (12 PSI PRESSURE RISE)

NRC REQUIRED SENSITIVITY ANALYSES FOR AN UNCERTAINTY RANGE BETWEEN IDCOR POSITION AND THAT OF THEIR OWN CONTAINMENT LOADING WORKING GROUP (CLWG) o SANDIA EXPERIMENTS DEMONSTRATED POTENTIALLY LARGER EFFECTS FOR SIMPLIFIED GEOMETRIES o EFFECTS OF WATER NOT INCLUDED IN NRC EXPERIMENTS AT THAT TIME

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2.3 DiBECT CONTAINMENT HEATING HISTORICAL EERSPECTIVE (CONTINUED) o EXPERIMENTS ONGOING AT SURTSEY AND BROOKHAVEN o RECENT SANDIA CALCULATIONS WITH CONT N INDICATE THE POTENTIAL FOR SIGNIFICANT ADDITIONAL HYDROGEN GENERATION WHEN WATER IS PRESENT

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2.3 DIRECT CONTAINMENT HEATING APPROACH TO RESOLUTION

1. ADDRESS THE ISSUE WITH DESIGN FEATURES INCLUDING A CAVITY CONFIGURATION THAT LIMITS DEBRIS DISPERSAL (EPRI REQUIREMENTS DOCUMENT, CHAPTER 5) o DESIGNS INCLUDE CAPABILITY FOR PRIMARY SYSTEM DEPRESSURIZATION UNDER SEVERE ACCIDENT CONDITIONS.

o DISPLACED CAVITY EXIT AREA TO SEPARATE DEBRIS FROM THE GAS l

o CAVITY COLLECTION VOLUME OF TWICE THE l CORE VOLUME  ;

2. SENSITIVITY ANALYSES OVER REASONABLE RANGES l lN PRA ADDRESSING DEBRIS MASS, HYDROGEN GENERATION, AND EFFECTS OF PRESENCE OF l WATER Y l

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2.4 CONTAINMENT PERFORMANCE flDCOR ISSUE 15)

ISSUE DEFINITION SEVERE ACCIDENT ASSESSMENT OF CONTAINMENT FOR PERFORMANCE INVOLVES THE POTENTIAL CONTAINMENT FAILURE DUE TO:

o OVERTEMPERATURE (NOT SIGNIFICANT FOR A PWR, GIVEN THAT DIRECT CONTACT WITH CORE MATERIAL CAN BE PRECLUDED BY DESIGN) o OVERPRESSURIZATION RESULTING IN GROSS RUPTURE (A LARGE FAILURE ALLOWING RAPID DEPRESSURIZATION) o OVERPRESSURIZATION RESULTING IN LEAK-BEFORE-BREAK (INCREASING LEAKAGE UNTil PRESSURIZATION IS TERMINATED)

)

4 2.4 CONTAINMENT PERFORMANCE HISTORICAL PERSPECTIVE IDCOR CONSIDERED THE DOMINANT FAILURE MODE TO BE l LEAK-BEFORE-BREAK o LINER FAILURE AT PENETRATIONS PREDICTED AT HIGH CONTAINMENT STRAINS o MAAP MODEL DEVELOPED AND BENCHMARKED TO PREDICT STRA!N FAILURE FOR CONCRETE OR l STEEL CONTAINMENTS: FAILURE AT ULTIMATE STRESS ALSO MODELLED I

NRC REQUIRED SENSITIVITY STUDIES FOR A SPECTRUM OF CONTAINMENT FAILURE MODES FOR VARIOUS CONTAINMENT DESIGNS o FAILURE PRESSURE WAS PREDICTABLE FOR STEEL CONTAINMENTS, BUT LOCATION AND MODE OF FAILURE WERE UNCERTAIN; THE NRC SPECTRUM INCLUDES A THRESHOLD MCE EL WITH NO LEAKAGE BEFORE FAILURES OF VARIOUS SIZES o FAILURE MODE WAS PREDICTABLE FOR CONCRETE CONTAINMENTS, BUT FAILURE LOCATION AND PRESSURE WERE UNCERTAIN; THE NRC SPECTRUM AGAIN INCLUDED LARGE CONTAINMENT FAILURE SIZES AT THRESHOLDS BASED ON REINFORCEMENT YlELD OR PRESTRESSED TENDON STRAIN i

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2.4 CONTAINMENT PERFORMANCE APPROACH TO l RESOLUTION 1 PERFORM DETAILED, REALISTIC ANALYSIS TO ASSESS THE POTENTIAL FOR LEAKAGE AT PENETRATIONS PRIOR TO REACHING ULTIMATE CONTAINMENT FAILURE CONDITIONS (LEAK-BEFORE-BREAK)

2. INCLUDE A SENSITIVITY ANALYSIS IN THE PRA TO ASSESS THE IMPACT OF VARIOUS CONTAINMENT LEAK SIZES AND LOCATIONS

3. DEVELOP CONTAINMENT DESIGNS THAT PREVENT DIRECT CONTACT OF CORE DEBRIS WITH THE CONTAINMENT BOUNDARY l

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1 2.5 HYDROGEN IGNITION AND BURNING 'lDROR_lSSUE

17) ISSUE DEFINITION l

POTENTIAL FOR EARLY CONTAINMENT FAILURE DUE TO ,

THE TEMPERATURE AND PRESSURE LOAfIS IMPOSED BY HYDROGEN COMBUSTION I

o GLt \L HYDROGEN BURN CAN PRODUCE SIGNIFICANT LO/. >S, BUT THEY ARE LOADS THAT CAN BE ACCOMMODATED BY CONTAINMENT DESIGN o THE MAGNITUDE AND TIMING OF HYDROGEN BURN LOADS, IF NOT ALSO PRECLUDED, MUST BE DETERMINED BY ANALYSES USING HYDROGEN COMBUSTION MODELS l

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2.5 HYDROGEN IGNTTION ANQEURN;NG HISTORICAL, PERSPECTIVE IDCOR'S RESPONSE TO THIS ISSUE INCLUDED:

o BENCHMARKING OF THE IDCOR BURN MODELS (GLOBAL AND IGNITER BURNS) AGAINST A VARIETY OF EXPERIMENTAL CONFIGURATIONS a FLAME TEMPERATURE IGNITION CRITERION WAS CHECKED FOR CONSISTENCY WITH BURN COMPLETENESS o AGREED TO STANDARD PROBLEM EXERCISE. MAAP RESULTS WERE GENERATED AND SUBMITTED.

NRC'S RESPONSE TO THIS ISSUE INCLUDED:

o COMPLETION OF ONGOING RESEARCH IN LARGE-SCALE HYDROGEN BURNS o AGREED TO STANDARD PROBLEM EXERCISE. HECTR PROGRAM RESULTS TO BE PROVIDED.

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l 2.5 HYDROGEN 'GNITION AND BURN'NG AP'2 ROACH TO RESOLUTION

1. THE ADVANCED PWR CONTAINMENT WILL BE DESIGNED IN A MANNER THAT PRECLUDES GLOBAL HYDROGEN DETONATION AND ACCOMMODATES GLOBAL BURNS, AS STIPULATED IN THE EPRI REQUIREMENTS DOCUMENT, CHAPTER 5 Y

' '(s y o THE CONTAINMENT DESIGN WILL ENSURE THAT THE UNIFORMLY DISTRIBUTED CONCENTRATION

/j OF HYDROGEN DOES NOT EXCEED 13% UNDER

?c \ , t' REALISTIC SEVERE ACCIDENT CONTAINMENT al' , CONDITIONS f:,d 3/ o THE CONTAINMENT DESIGN WILL ENSURE I

EFFECTIVE MIXING SO THAT LOCAL DETONATIONS ARE UNLIKELY; AREAS IN WHICH HYDROGEN COULD BE INTRODUCED WILL BE INVESTIGATED AND REQUIRED TO ACCOMMODATE DETONATION, IF IT IS NOT SO UNLIKELY w,s

2.5 liYDRQGENJGNEDON AND BURNING APPROACH TO RESOLUTION (CONTINUED)

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i o A STRUCTURAL ANALYSIS VERIFYING THAT THE CONTAINMENT CAN WITHSTAND PRESSURES RESULTING FROM GLOBAL HYDROGEN BURNS OF '

UP TO 13% HYDROGEN CONCENTRATION WILL BE PERFORMED: THIS ANALYSIS WILL BE PART OF A BEST ESTIMATE ASSESSMENT OF CONTAINMENT PERFORMANCE FOR PRA SEQUENCES

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o THE TECHNICAL BASIS FOR THE 13%

CONCENTRATION PRECLUDING DETONATION WILL BE PROVIDED

2. THE MAAP HYDROGEN BURN MODEL WILL BE REVIEWED AND UPDATED TO ADDRESS THI, NRC CONCERNS; UPDATES WILL INCLUDE MODELS FOR IGNITION, BURN COMPLETENESS, AND TRANSITION BETWEEN INCOMPLETE AND COMPLETE BURN 3

j 2.6 DEBRIS COOLABILITY flDCOR ISSUE 10) ISSUE DEFINITION ALWRS ARE DESIGNED TO ESTABLISH A SAFE STABLE l STATE FOR THOSE SCENARIOS IN WHICH THE REACTOR VESSEL FAILS WITH CORE DEBRIS FALLING INTO THE REACTOR CAVITY l

o IDCOR ISSUE 10 lNVOLVED ALL ASPECTS OF CORE DEBRIS IN THE REACTOR CAVITY INTERACTING THERMALLY AND CHL'MICALLY WITH THE l STRUCTURAL CONCRETE o THE SUB-ISSUE OF THERMAL AND PRESSURE LOADINGS ON THE CONTAINMENT WAS RESOLVED, SUBJECT TO CONTINUING COMPARISON OF MODELS WITH EXPERIMENTAL DATA AS IT BECOMES AVAILABLE (AN ELEMENT OF ARSAP) o THE SUB-ISSUE OF DEBRIS COOLABillTY (I.E.

QUENCHING OF THE DEBRIS AND THE ESTABLISHMENT OF A HEAT TRANSPORT PATH TO THE ULTIMATE HEAT SINK) WAS NOT RESOLVED ,

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[ h 2.6 DEBRIS COOLABILITY HISTORICAL PERSPECTIVE IDCOR ASSESSED DEBRIS COOLABILITY BASED ON TMI-2 QUENCHING AND ON EXPERIMENTS CONDUCTED DY SANDIA AND EPRI I

o A CRITICAL HEAT FLUX REPRESENTATION OF QUENCHING WAS FOUND TO BE ADEQUATE 1

l o LAVA BED QUENCHING EXPERIMENTS DEMONSTRATE SUFFICIENT CRACKING TO ENSURE THAT CONDUCTION WILL NOT BE LIMITING o MAAP MODELS REFLECT THESE CONCEPTS THE NRC CONSIDERED THE AVAILABLE DATA INSUFFICIENT TO SUBSTANTIATE THE IDCOR POSITION o EARLY EXPERIMENTS AT SANDIA FOCUSED ON CORE-CONCRETE ATTACK THOUGH AVAILABLE HEAT FLUX RESULTS WERE CONSISTENT WITH THE IDCOR APPROACH o ON-GOING SURC TESTS WERE EXPECTED TO PROVIDE DATA TO TEST THE VALIDITY OF THE IDCOR MODELS FOR DEBRIS COOLABILITY

-i, 2.6 D1BRIS COOLABILITY APPROACH TO REiS.0LUTION

1. PROVIDE DESIGN REQUIREMENTS ASSURING AN l APPROPRIATELY SIZED CAVITY AND THE AVAILABILITY OF WATER (EPRI REQUIREMENTS l

DOCUMENT) l l o SUFFICigNT CAVITY SURFACE AREA TO AFFORD 0.02 M PER RATED MEGAWATT OF THERMAL POWER o FLOW PATHS, AREAS, CURBS AND DRAINS TO ENSURE CAVITY FLOODING o IRWST CONFIGURED TO OVERFLOW TO CAVITY AT APPROPRIATE EXCESS ABOVE NORMAL OPERATING VOLUME o CONTAINMENT ARRANGED TO AFFORD HEAT TRANSPORT PATHS AND ALTERNATIVE MEANS TO PROVIDE ADDITIONAL WATER

2. PROVIDE THE TECHNICAL BASIS TO ESTABLISH DEBRIS COOLABILITY GIVEN THE ABOVE REQUIREMENTS

Enclosure 4

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12

Enclosure 5? -

COMPARISON OF THE LIMITS OF VARIOUS COMBUSTION MO COMPOSITION THERMODYNAMIC FLAMMABILITY FLAMZ ACCELERATION *'

DET0?MTION '

STATE LIMITS LIMITS e LIMITS Lean H2 -Air T-20*C, P=1 etm 4-9% H2 (1) 10% H2 (3) 11.7% H2 (7)

Lean H2 -Gir T-100*C,. P-1 atm 4.5% H2 (2) '

9.5% H2C7)

Rich H2 -Air T-20*C, P=1 ata 74.2% H2 (1) 73% H2 (3) 75% H2 (7)

Rich U2 -A'r T-100*C, P-1 atm 78.5% 2H (2) (extrapol.)

77% H2 (7)

Steam-Diluted Stoichiometric H2 -Air T-100*C, P-1 ata

>52% 2H 0(2) (to inert) >35% 2H 0(4) (to inert)

Helium-Diluted >35% 2H 0(7) (to inert)

Stoichiometric H2 -02 T-22*C, P-1 ata

>86.5% He(5) (to inert)

>86.5% Be(6) (to inert)

1. Covard, H. F. and Jones, C. V.,

Bulletin 503, 1952. "Limits of Flammability of Cases and Vapor," U .S. Bureau of Mines limit.) (4% H2 is the upward propagation limit and 9% U 2 is the downward propagation 20 Marshall, B. V.,

Vessel," SAND 84-0383. "Hydrogen: Air: Steam Flammability Limits and Combustion Characteristics in the FITS 30 Knystautas, R., Lee, J. H.,

International Combustion Symposium.Peraldi, 0.,

"Criteria for Transition to Detonation in Tubes " 21s t ,

4.

Brehm,R.unpublished data obtained at Technical University Munich. . i .!

5. Kumar, K.,

pp 245-262, 1985. "Flammability Limits of Hydrogen-Oxygen-Diluent Mixtures," J . Fire Sciences, V3, 6.

70 Kumar, Stamps, D. recent V., unpublished data obtained at Whiteshell Nuclear Research Establishment ' .

recent unpublished data obtained in the HDT at Sandia National Laboratories .

+

Acceleration of flame to the isobaric sound speed.

i

• a e

- - July 28, 1988 i

DISTRIBUTION:

1 Central File NRC PRDR PDSNP Reading LRubenstein EHylton GVissing

.. 0GC-Rockville EJordan BGrimes

! NRC Participants ACRS (10) l i

)