ML20203G692
| ML20203G692 | |
| Person / Time | |
|---|---|
| Site: | Perry, Grand Gulf, River Bend, Clinton, 05000000 |
| Issue date: | 07/25/1986 |
| From: | Kintner L Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8608040008 | |
| Download: ML20203G692 (35) | |
Text
Kicog y ? UNITED STATES
'g y .+ g NUCLEAR REGULATORY COMMISSION '
WASHINGTON, D. C. 20555
. JUL 251986 Docket Nos. 50-416/417 50-461 50-458/459 50-440 LICENSEES: Mississippi Power & Light Company Illinois Power Company Gulf States Utilities Cleveland Eler'.ric Illuminating Company FACILITIES: Grand Gu F sclear Station, Units 1 and 2 Clinton, Unit 1 River Bend Units 1 and 2 Perry, Unit 1
SUBJECT:
SUMMARY
OF JUNE 19, 1986 MEETING WITH MARK III CONTAINMENT HYDR 0 GEN CONTROL OWNERS GROUP (HC0G) REGARDING MODIFICATIONS OF THE CLASIX-3 COMPUTER CODE AND SECONDARY BURNING IN A QUARTER SCALE TEST The purpose of the meeting was to discuss recent Quarter Scale Test Facility (QSTF) test results and modifications to the CLASIX-3 computer code. Enclosure 1 is a list of attendees. Enclosure 2 is a handout prepared by HC0G regarding the QSTF tests. Enclosure 3 is a handout prepared by HC0G regarding the CLASIX-? computer code.
HC0G described a recent QSTF test in which diffusion flames were extinguished on the suppression pool surface and reignited above the hydraulic control unit (HCU) floor. This type of burning, called secondary burning, occurred after a large quantity of hydrogen had been injected. Secondary burning did not occur in previous quarter scale tests because the oxygen concentration in the simulated containment was above 8% due to air added by a continuous air purge of video camera lenses inside the sinulated containment. The total air purge rate was 0.0285 pounds of air per second in the QSTF. This quantity of air addition would not be present in a full scale containment under accident conditions.
HC0G considered several factors involved in the secondary burning phenomenon as outlined on Pages 10 through 14 of Enclosure 2. HC0G concluded that it is not necessary to investigate secondary burning further, nor to apply it to plant specific analyses of hydrogen burning following a degraded care accident. The staff has the following comments on the phenomenon and its application:
HC0G states the phenomenon was extremely localized and was only observed in the 45 degree chimney in which a simulated stuck open safety relief valve was located. The staff's comment is that HCOG should consider where secondary burning could occur in the Mark III containments and whether essential equipment would be affected.
8608040008 860725 PDR ADOCK 05000416 P PDR
HCOG states that the phenomenon occurred over a small range of oxygen concentration (between 6% and 8%) and after large quantities of hydrogen injection which occurred late in the simulated accident. The staff's comment is that HCOG should analyze for each Mark III plant, the potential for this range of oxygen concentration to occur late in the postulated accident sequence, considering means for air movement between the drywell and containment (for example, the drywell purge compressors and drywell vacuum breakers).
HC0G states that it is impractical to simulate oxygen depletion for each Mark III plant volume in the QSTF. The staff's comment is that it may be feasible to reduce the initial oxygen concentration in a quarter scale test to compensate for air addition via the cameras, and more closely simulate plant specific volumes.
The HCOG presented modifications made to the CLASIX-3 computer program to more accurately calculate containment pressure and temperature due to combustion of hydrogen following a postulated degraded core accident (Pages 4, 6 and 7 of Enclosure 3). HC0G also described the use of QSTF results to validate CLASIX-3 (Page 5 of Enclosure 3). Past and future analyses using CLASIX-3 are described on Pages 8, 9 and 10 of Enclosure 3. HC0G conclusions are given on Page 11.
The staff has the following comments on the presentation of the CLASIX-3 analyses:
It is not apparent that the CLASIX-3 code can be validated through the QSTF. Below the diffusion flame extinguishment level, the burning phenomenon, called localized combustion, was characterized as not being anchored to a fixed location. The CLASIX-3 code is not able to calculate spatially dependent hydrogen burning.
- The method of averaging QSTF measured temperatures for comparison with the CLASIX-3 code calculated temperatures does not appear to adequately consider temperature spikes observed in the tests.
The use of the Perry plant for generic validation analyses may not be appropriate, because of the large quantity of steel in the Perry wetwell to serve as a heat sink compared to the other Mark III plants.
The cooling effectiveness of sprays assuming sheet flow compared to drop flow would appear to be much less than a factor of 1/2 as assumed, based on considerations of the water surface areas involved.
The containment response sensitivity study is narrower in scope than that described in the program plan. For example, cases involving no spray and no spray carry-over will not be analyzed and the effects of a range of flame speeds and heat transfer coefficients will rot be considered.
The effect of a range of steam releases to the drywell during hydrogen release should be investigated. The presently considered mass ratio of steam-to-hydrogen of 500/1 suppresses hydrogen burning in the drywell.
At the end of the meeting, HC0G said it would further investigate the secondary burn phenomenon. The final test report will address this phenomenon.
Sincerely, ,
vbs Lester L. Kintner, Project Manager BWR Project Directorate No. 4 Division of BWR Licensing
Enclosures:
As stated cc w/ enclosures:
See next page J
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. Mr. Oliver D. Kingsley, Jr.
Mississippi Power & Light Company Grand Gulf Nuclear Staiton cc:
Robert B. McGehee, Esquire The Honorable William J. Guste, Jr.
Wise, Carter, Child, Steen and Caraway Attorney General P.O. Box 651 Department of Justice Jackson, Mississippi 39205 State of Louisiana Baton Rouge, Louisiana 70804 Nicholas S. Reynolds, Esquire l Bishcp, Liberman, Cook, Purcell Office of the Goverror and Reynolds State of Mississippi 1200 17th Street, N.W. Jackson, Mississippi. 39201 Washington, D. C. 20036 Attorney General Mr. Ralph T. Lally Gartin Building Manager of Quality Assurance Jackson, Mississippi 39205 Middle South Servir.es, Inc.
P.O. Box 61000 Mr. Jack McMillan, Director New Orleans, Louisiana 70161 Division of Solid Waste Management Mississippi Department of Natural Mr. Larry F. Dale, Director Resources Nuclear Licensing and Safety Bureau of Pollution Control Mississippi Power & Light Company Post Office 3ox 10385 P.O. Box 23054 Jackson, Mississippi 39209 Jackson, Mississippi 39205 Alton B. Cobb, M.D.
Mr. R. W. Jackson, Project Engineer State Health Officer Bechtel Power Corporation State Board of Health 15740 Shady Grove Road P.O. Box 1700 Gaithersburg, Maryland 20877-1454 Jackson, Mississippi 39205 Mr. Ross C. Butcher President Senior Resident Inspector Claiborne County Board of Supervisors U.S. Nuclear Regulatory Commission Port Gibson, Mississippi 39150 Route 2, Box 399 Port Gibson, Mississippi 39150 Mr. Ted H. Cloninger Vice President, Nuclear Engineering Regional Administrator, Region II and Support l U.S. Nuclear Regulatory Co.nmission, Mississippi Power & Light Company 101 Marietta Street, N.W., Suite 2900 Post Office Box 23054 Atlanta, Georgia 30323 Jackson, Mississippi 39205 Mr. J. E. Cross Grand Gulf Nuclear Station Site Director Mississippi Power & Light Company P.O. Box 756 Port Gibson, Mississippi 39150 Mr. C. R. Hutchinson GGNS General Manager Mississippi Power & Light Company Post Office Box 756 Port Gibson, Mississippi 39150
, Mr. Frank A. Spangenberg Clinton Power Station Illinois Power Company Unit 1 cc:
Mark Jason Assistant Attorney General Public Utilities Division Office of the Attorney General State of Illinois Center Richard B. Hubbard 100 West Randolph Street - 12th Floor Vice President Chicago, Illinois 60601 Technical Associates 1723 Hamilton Avenue - Suite K Mr. D. P. Hall San Jose, California 95125 Vice President Clinton Power Station Chairman of DeWitt County P. O. Box 678 c/o County Clerk's Office Clinton, Illinois, 61727 DeWitt County Courthouse Clinton, Illinois 61727 Mr. John Greene Manager-Nuclear Station Engineering Dpt. Director, Criteria & Standards (ANR-460)
Clinton Power Station Office of Radiation Programs P. O. Box 678 U. S. Environmental Protection Agency Clinton, Illinois 61727 Washington, DC 20460 Sheldon Zabel, Esquire EIS Review Coordinator Schiff, Hardin & Waite Environmental Protection Agency 7200 Sears Tower Region V 233 Wacker Drive 230 S. Dearborn Street Chicago, Illinois 60606 Chicago, Illinois 60604 Resident Inspector Director, Eastern Environmental V. S. Nuclear Regulatory Commission Radiation Facility RR 3, Box 229 A U. S. Environmental Protection Agency Clinton, Illinois 61727 P. O. Box 3009 Montgomery, Alabama 36193 Mr. R. C. Heider Project Manager Illinois Department of Nuclear Safety Sargent & Lundy Engineers Division of Engineering 55 East Monroe Street 1035 Outer Park Drive, 5th Floor Chicago, Illinois 60603 Springfield, Illinois 62704 Mr. L. Larson Project Manager General Electric Company 175 Curtner Avenue, N/C 395 San Jose, California 95125 l
Regional Administrator, Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137
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. Mr. William J. Cahill, Jr.
Culf States Utilities Company River Bend Nuclear Plant cc:
Troy B. Conner, Jr. , Esq. Ms. Linda B. Watkins/Mr. Steven Irving Conner and Wetterhahn Attorney at Law 1747 Pennsylvania Avenue, NW 355 Napoleon Street Washington, D.C. 20006 Baton Rouge, Louisiana 70802 Mr. William J. Reed, Jr. Mr. William H. Spell, Administrator Director - Nuclear Licensing Nuclear Energy Division Gulf States Utilities Company Louisiana Department of P. O. Box 2951 Environmental Affairs Beaumont, Texas 77704 P. O. Box 14690 Baton Rouge, Louisiana 70898 Richard M. Troy, Jr., Esq.
Assistant Attorney General in Charge Mr. J. David McNeill, III State of Louisiana Department of Justice William G. Davis, Esq.
234 Loyola Avenue Department of Justice New Orleans, Louisiana 70112 Attorney General's Office 7434 Perkins Road Resident Inspector Baton Rouge, Louisiana 70808 P. O. Box 1051 St. Francisville, Louisiana 70775 H. Anne Plettinger 3456 Villa Rose Drive Gretchen R. Rothschild Baton Rouge, Louisiana 70806 Louisianians for Safe Energy, Inc.
1659 Gler.more Avenue Baton Rouge, Louisiana 70775 President of West Feliciana Police Jury Regional Administrator, Region IV P. O. Drawer N.
U.S. Nuclear Regulatory Commission St. Francisville, Louisiana 70775 Office of Executive Director for Operations 611 Ryan Plaza Drive, Suite 1000 Arlington, Texas 76011 -
Mr. J. E. Booker Manager-Engineering, Nuclear Fuels &
Licensing Gulf States Utilities Company P. O. Box 2951 Beaumont, Texas 77704
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, Mr. Murray R. Edelman Perry Nuclear Power Plant The Cleveland Electric Units 1 and 2 Illuminating Company cc:
Jay Silberg, Esq. Mr. James W. Harris, Director Shaw, Pittman, & Trowbridge Division of Power Generation 1800 M Street, N. W. Ohio Department of Industrial Washington, D. C. 20006 Relations 2323 West 5th Avenue Donald H. Hauser, Esq. Post Office Box 825 The Cleveland Electric Columbus, Ohio 43216 Illuminating Company P. O. Box 5000 The Honorable Lawrence Logan Cleveland, Ohio 44101 Mayor, Village of Perry 4203 Harper Street Resident Inspector's Office Perry, Ohio 44081 U. S. Nuclear Regulatory Commission Parmly at Center Road The Honorable Robert V. Orosz Perry, Ohio 44081 Mayor, Village of North Perry North Perry Village Hall Regional Administrator, Region III 4778 Lockwood Road U. S. Nuclear Regulatory Commission North Ferry Village, Ohio 44081 799 Roosevelt Road Glen Ellyn, Illinois 60137 Attorney General Department of Attorney General Donald T. Ezzone, Esq. 30 East Broad Street Assistant Prosecuting Attorney Columbus, Ohio 43216 105 Main Street Lake County Administration Center Ohio Department of Health
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Painesville, Ohio 44077 Attn: Radiological Health Program Director Ms. Sue Hiatt P. O. Box 118 OCRE Interim Representative Columbus, Ohio 43216 8275 Munson Mentor, Ohio 44060 Planning Coordinator 361 East Broad Street Terry J. Lodge, Esq. P. O. Box 1735 618 N. Michigan Street Columbus, Ohio 43215 Suite 105 Toledo, Ohio 43624 Ohio Environmental Protection Agency Division of Planning John G. Cardinal, Esq. Environmental Assessment Section Prosecuting Attorney P. O. Box 1049 Ashtabula County Courthouse Columbus, Ohio 43216 Jefferson, Ohio 44047 Mr. Arthur Warren, Chairman Eileen M. Buzzelli Perry Township Board of Trustees The Cleveland Electric 4169 Main Street Illuminating Company Perry, Ohio 44081 P. O. Box 97 E-210 Perry, Ohio 44081
,' Enclosure 1 r
List of Attendees - HC0G Meeting 6/19/86 Enercon Services NRC Matthew Rager Dean Houston W. M. Davis A. Notafrancesco Patrick Thurman Jack Kudrick Bob Evans Wayne Houston John Richardson John L. Knop L. L. Kintner Gulf States Utilities Marvin Morris Randy Langely GMF Associates G. Martin Fuls Illinois Power Company Timothy A. Byam Cleveland Electric Illumination Company Emin B. Ortalan Mississippi Power & Light Company i Michael J. Manski Electric Power Research Institute
- John F. Hosler i
Westinghouse Electric Corporation V (Seena) Sriwivas e
Enclosure 2 0
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1/4 SCALE TESTING 9
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TESTING STATUS o Initiated production testing in (arly January, 1986 o Encountered several problems with testing Maintaining initial conditions Blockages in LOCA vent hydrogen supply lines o HCOG elected to install system to eliminate condensation on thermocouple beads Electrical current through thermocouples System has proven very effective o Encountered additional facility degradation due to aging Necessitated replacement of thermocouple connectors o Resumed production testing in early May Grating installed in PNPP geometry for all production tests o Six of the eight Perry production tests have been satisfactorily completed to date Test P.06.1 completed, showed a different combustion phenomenon
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QUILIEE o Observation of the phenomenon 4
Past testing Present experience o Effect on HCOG Program Schedule Facility o Evaluation of the phenomenon Timing of the phenomenon Low probability of the phenomenon l
l Mitigating factors I
o Conclusions l
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PAST TESTING Testing in the 1/20 Scale Facility o 1/20 scale tests completed in 1983 o Diffusion flames observed to extinguish on suppression pool and reignite above HCU floor very late in hydrogen injection Termed secondary burning Postulated to result from oxygen depletion o Due to uncertainties in 1/20 scale test facility, no conclusions were drawn regarding occurrence of phenomenon at full scale 1/20 scale was vented 1/20 scale did not model sprays l
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PAST_TESTlHG (CONT)
Testing in the 1/4 Scale Facility o HCOG undertook 1/4 scale test program to measure diffusion flame thermal environment o Testing designed to simulate HGEs through recovery with total hydrogen production equivalent to 30% MWa o Testing started in summer, 1985 22 scoping tests run 6 production tests run prior to P.06.1 o No secondary burning observed prior to cerry Production Test P.06.1.
o Lack of secondary burning in 1/4 scale appeared reasonable based on improved mixing characteristics in larger scale tests ,
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EhST TEST 1EG lCDDL 1 o Oxygen concentration at end of combustion is approximately 9% by volume (dry)
The Oxygen concentration appeared to be reasonable Further evaluation indicated that air addition through the camera purge and larger scaled volume compared to Perry may be responsible for the 9% oxygen concentration Five cameras are installed in the facility Camera purge rate is 0.0057 lbm/sec per camera For long duration tests (i.e., 75% MWR test), the camera ,
purge can affect the oxygen concentration at end of test l
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l Volume in QSTF is representative of GGNS t
Volumes in other Mark III facilities differ from GGNS i
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o Discussions held on approaches to modify end point oxygen concentrations l
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REESEBT o Due to miscommunication with testing contractor, camera purges were not run continuously during P.06.1 In all previous tests, purge was run continuously o Resulted in reduction in oxygen concentration at end of test o Secondary burning was measured in the 45 degree chimney with global oxygen concentration below 8%
In previous tests the end point oxygen concentration stayed above 8%
l o Region of 45 degree chimney which showed evidence of secondary burning is limited o Thermocouple traces at the 1/8 radius moving from adjacent to the steam tunnel clockwise towards the 135o chimney 6emonstrate radially and azimuthal attenuation in secondary burning
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EEEECT_QB_BCOG_PEDGEAE o Secondary burning is different from the two phenomena previously observed in the 1/4 scale test program, these include:
Diffusive burning on the suppression pool surface s
Localized combustion o A detailed investigation of secondary burning would have significant adverse impacts on program schedule L.d resource commitments Require significant schedule extension to investigate Physical constraints limit investigation of the phenomenon l
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EHISICAL_CDUSTEAINIS o 1/4 scale test facility has fundamental, physical limitations associated with the investigation of this phenomenon Facility designed to allow definition of the most probable thermal environment produced by diffusion flames anchored to the suppression pool surface Instrumentation layout developed to assure adequate measurement of temperatures produced by burning at the suppression pool Investigation of secondary burning would entail additional instrumentation, reinstrumentation, scoping tests and final tests Purge over camera lenses required to assure accurate visual record Facility as designed cannot reach sufficiently low oxygen concentration to investigate secondary burning if purges are on All four Mark III plants have different containment volumes Impractical to accurately represent expected oxygen depletion due to volume differences Cannot modify volume of facility without expenditure of extensive resources
EYALU8 TION _QE_THE_IHENDEENON o Numerous factors affect consideration of secondary burning Timing of the phenomenon Low probability associated with the occurrence of the phenomenon Factors which mitigate the effects of the phenomenon on the thermal environment I
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r I- TimlDS_9f_EbEDQmensD o Secondary burning occurs over a narrow range of oxygen concentration late in the transient Oxygen concentration remained above 8% at end of previous 75% MWR tests Secondary Burning not observed in previous tests Secondary burning observed when oxygen concentration decreased below 8% ,
Hydrogen combustion only occurs at oxygen concentrations at or sbove approximately 6%
o Since oxygen concentration throughout containment is reasonably uniform and secondary burning occurs only below 8% oxygen, from 56 to 70% of the zircaloy cladding in the active fuel region must be oxidized before oxygen concentration can reach 8%
' - Thus, secondary burning occurs only late in a HGE
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II. . Low _Erskability_of_QscurInnse o Hydrogen generation events are low probability events with significant uncertainty HCOG has dealt with uncertainty by attempting to identify the most probable sequence of events o Degraded core accidents which can create conditions which allow secondary burning involve artificial conditions Most probable event: 5000 GPM reflood (ECCS) with stall MWR and event termination Less probable event: Low flow reflood (e.g.,150 GPM via CRD) resulting in small MWR and event termination Least probable event: Core reflood which cools core but allows continued low hydrogen generation rate in excess of 60% MWR
[ o Considerable assumptions and uncertainty are inherent in
! calculating a long term, non-mechanistic hydrogen production
" tail" to reach 75% MWR l
i.e., small decreases in " tail" calculations could revise the
! 0.1 lbm/sec value and eliminate secondary burning phenomenon I o Secondary burning could be reduced or eliminated via alternate accident sequence (e.g., steam blowdown from RPV to drywell would increase oxygen concentration in containment)
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1 Illi__Eitigating_Eastors o Several factors will mitigate the consequences of secondary burning As secondary burning can only occur after recovery, containment sprays would be available Sprays or unit coolers can potentially preclude or delay secondary burning because of Increased turbulence in the containment, and Improved mixing of gases from the upper containment Sprays can provide cooling for secondary burning which would mitigate the thermal environment Secondary burning is extremely localized Only observed in the 45 degree chimney in which the SORV was located adjacent to other ADS valves Limited to a small volume in the 45 degree chimney Effect of secondary burning also mitigated because of redundant equipment Secondary burning would affect, at most, one train of equipment Equipment located outside areas influenced by this l phenomenon are not affected by the secondary burning thermal environment o Thus, effect of secondary burning is mitigated by containment sprays, unit coolers, localization of phenomenor, and redundancy of equipment I
CanclusiDDS o Not necessary to investigate secondary burning Secondary burning occurs only late in a 75% MWR hydrogen generation event Low probability associated with the occurrence of secondary burning i
Several factors mitigate the effects of secondary burning o Because of physical constraints of the 1/4 scale test facility, detailed investigation of this phenomenon would impose significant burdens on program 1
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Enclosure 3 NRC MEETING JUNE 19, 1986 CLASIX-3 ANALYSIS o BACKGROUND o CLASIX-3 MODIFICATIONS o CLASIX-3 VALIDATION o GENERAL CLASIX-3 INPUT NODEL j
o GENERIC CLASIX-3 ANALYSES i
I o FUTURE ANALYSES l
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SUMMARY
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e BhCEGBODED o HCOG PREVIOUSLY SELECTED AND USED CLASIX-3 FOR 4
PREDICTING PRESSURE AND TEMPERATURE FROM DEFLAGRATION TYPE HYDROGEN COMBUSTION CLASIX-3 BASE CASE ANALYSES AND SENSITIVITY STUDIES SUBMITTED BY HCOG IN JANUARY 1982 il o NRC REVIEW IDENTIFIED SEVERAL CONCERNS AND REQUESTED BCOG TO INCORPORATE THESE CONCERNS PRIOR TO ADDITIONAL USE TO DEFINE THERMAL ENVIRONMENTS NUREG-0588 HEAT TRANSFER METHODOLOGY SUPPRESSION POOL BYPASS LEAKAGE REACTOR COOLANT PRESSURE BOUNDARY HEAT LOADS i
j o 1/4 SCALE TESTING HAS DEMONSTRATED THAT OTHER THAN THE INITIAL LITE-OFF BURN, DEFLAGRATIONS DO NOT OCCUR LOCALIZED COMBUSTION OCCURS BELOW THE DIFFUSION FLAME EXTINGUISHMENT LIMIT l
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BACEGBOUND_1 Cont 1 o THEREFORE, AS DESCRIBED IN TASKS 8,10, AND 12, HCOG'S PLAN TO DEFINE THERMAL ENVIRONMENTS BELOW THE DIFFUSION FLAME EXTINGUISHMENT LIMIT IS:
REVISE THE CLASIX-3 MODEL TO ADDRESS NRC CONCERNS REVISE THE CLASIX-3 MODEL AND DEVELOP INPUT PARAMETERS TO MAKE THE RESULTS MORE REALISTIC BUT STILL CONSERVATIVE COMPLETE 1/4 SCALE PREDICTIONS USING THE REVISED CLASIX-3 MODEL AND ASSUMPTIONS VALIDATE CLASIX-3 BY SHOWING THE 1/4 SCALE PREDICTION IS CONSERVATIVE RELATIVE TO THE MEASURED TEST RESULTS (TASK 12)
COMPLETE GENERIC CLASIX-3 ANALYSIS TO DEFINE THE CONTAINMENT (TASK 8) AND DRYWELL (TASK 10)
THERMAL ENVIRONMENT l
o THE HCOG REPORT SUBMITTED JUNE 10 PROVIDES THE RESULTS OF THESE TASKS 1
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CLASIX:3_EDDIEICATIDES o SINCE THE PREVIOUS BASE CASE ANALYSES AND SENSITIVITY STUDIES SUBMITTED JANUARY 1982, HCOG HAS IMPLEMENTED SEVERAL CHANGES TO THE CLASIX-3 MODEL TO :
ADDRESS NRC CONCERNS IMPROVE THE MODEL AND MAKE IT MORE REALISTIC BUT STILL CONSERVATIVE o CLASIX-3 BAS BEEN REVISED TO INCLUDE NUREG-0588 HEAT TRANSFER METHODOLOGY
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HEAT TRANSFER MODEL IS BASED UPON A COMBINATION NUREG-0588, BTP CSB 6-1 AND CONTEMPT OF COMPUTER PROGRAM THE HEAT TRANSFER COEFFICIENT FOR THE CONDENSING REGION OF HEAT TRANSFER IS DEFINED BY TABULAR VALUES CONTAINED IN BTP CSB 6-1 AND CONTEMPT IF THE WALL SURFACE TEMPERATURE IS HIGHER THAN THE DEW POINT OF THE ATMOSPHERE, THE HEAT
, TRANSFER IS GOVERNED BY THE FILM COEFFICIENT DETERMINED FROM THE SAME CORRELATION AS USED IN CONTEMPT CONSISTENT WITH NUREG-0588, 92% OF THE CONDENSING HEAT TRANSFER IS ASSUMED TO BE DERIVED FROM CONDENSING WATER VAPOR AND THE REMAINING 8% IS ASSUMED TO BE REMOVED DIRECTLY i FROM THE BULK COMPARTMENT ATMOSPHERE i
o CLASIX-3 WAS MODIFIED TO INCLUDE THE NATURAL CIRCULATION MODEL, CONSISTENT WITH THE MODEL AS SUBMITTED BY GSU.
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CLASIX:1_YALIDATION o IN ORDER TO VALIDATE THE CLASIX-3 METHODOLOGY A COMPARISON OF THE CLASIX-3 PREDICTIONS TO QSTF VOLUME AVERAGED TEMPERATURES FOR TESTS S-14 AND S-15 WAS CONDUCTED 8
o THE QSTF WAS CLOSELY MODELED BY THE CLASIX-3 COMPUTER PROGRAM. ACTUAL QSTF DESIGN PARAMETERS WERE USED FOR DEVELOPING THE MODEL HEAT SINK SURFACE AREAS FLOW PATHS ACTUAL VOLUMES FROM QSTF SPRAY SYSTEM PARAMETERS 4
o THE ACTUAL HYDROGEN / STEAM RELEASE HISTORIES USED IN THE QSTF WERE USED FOR THE CLASIX-3 PREDICTIONS AS MEASURED IN THE QSTF, THE CLASIX-3 MODEL SUPPRESSED BURNING UNTIL HYDROGEN REACHED 4%
THROUGHOUT THE ENTIRE CCiiTAINMENT VOLUME o BECAUSE OF LOCALIZED TEMPERATURE MEASUREMENT IN THE QSTF VOLUME AVERAGED TEMPERATURES WERE CALCULATED USING A WEIGHTED AVERAGING TECHNIQUE o THE RESULTS OF COMPARING THE VOLUME AVERAGED TEKPERATURES TO THE CLASIX-3 RESULTS, SHOW TSAT CLASIX-3 PREDICTED HIGHER TEMPERATURES THE BASE LINE TEMPERATURES AS PREDICTED BY CLASIX-3 FOR BOTH S-14 AND S-15, ALTHOUGH BIGHER, WERE SIMILAR TO THE BASE LINE TEMPERATURES AS CALCULATED USING QSTF DATA 1
CLASIX-3 ALSO PREDICTED HIGHER PRESSURES THAN THOSE ACTUALLY RECORDED AT THE QSTF BUT THE PROFILES WERE SIMILAR i
o CLASIX-3 PROVIDES REALISTIC YET CONSERVATIVE PREDICTIONS t
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GENEBaL_CLASIX:1_IEPUT_E0pIL o IN ADDITION TO THE MODEL CHANGES, SEVERAL CHANGES HAVE BEEN FADE IN THE CLASIX-3 ASSUMPTIONS AND METHODOLOGY o TO ADDRESS NRC CONCERNS, RCPB HEAT LOADS AND SUPPRESSION POOL BYPASS HAVE BEEN INCLUDED POST SCRAM RCPB HEAT LOADS USED FOR DESIGN BASIS ANALYSIS ADDITIONAL FLOWPATH BETNEEN DRYWELL AND INTERMEDIATE VOLUME WITH FLOW DEFINED BY TECH SPEC ALLOWABLE LEAKAGE o A 4 COMPARTMENT MODEL WAS USED
- DRYWELL
- WETWELL i
l - INTERMEDIATE VOLUME
- CONTAINMENT VOLUME o THE HYDROGEN AND STEAM RELEASE RATES BASED UPON MAAP, BWRCHUC, AND SEMI-MECHANISTIC MODEL:
RPV BLOWDOWN AND FIRST 2000 SECONDS DEFINED BY l
FAAP l
CORE HEATUP AND HYDROGEN / STEAM GENERATION l THROUGH RECOVERY DEFINED BY BWRCHUC 5000 GPM I
REFLOOD CASE WITH 50% ZR MELT FRACTION (CASE B)
BYDROGEN AND STEAM GENERATION FROM RECOVERY AND OUT TO 75% MWR DEFINED BY SEMI-MECHANISTIC MODEL (0.1 LB/SEC TAIL) o FOR THE DWB CASE, THE FLOW SPLIT BETWEEN THE SRV SPARGERS AND LOCA VENTS IS DEFINED MECHANISTICALLY l
USING MAAP.
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a GENEBBL_CLBSIX:3_INEUT_MDDEL_.ICoDL1 o CONTAINMENT SPRAYS ARE ACTIVATED 149 SECONDS AFTER THE AVERAGE TEMPERATURE REACHES 185oF AND REMAIN ACTIVE THROUGHOUT THE REMAINDER OF THE TRANSIENT SFRAY CARRYOVER FRACTIONS (CONTAINMENT TO INTERMEDIATE AND INTERMEDIATE TO WETWELL)
DEFINED AS IN PREVIOUS ANALYSIS BY AREA FRACTIONS THEN THE ENTIRE VALUE REDUCED BY 1/2 o COFBUSTIBLE GAS CONTROL DRYWELL MIXING SYSTEM ACTUATED AT 4% HYDROGEN IN THE DRYWELL o SUPPRESSION POOL DRAWDOWN AND MAKEUP MODELED; UPPER POOL DUMP 30 MINUTES AFTER EVENT INITIATION FOR DWB AND 40 MINUTES FOR SORV o BURN PARAMETERS WERE MODIFIED TO REDUCE THE CONSERVATISM IN CLASIX-3 AND BE CONSISTENT WITH 1/4 SCALE VALIDATION TO: .
- MINIMUM H2 V/O FOR IGNITION AT 0.06 l
- MINIMUM H2 V/O FOR PROPAGATION AT 0.06
- COMPLETENESS OF BURN AT 0.65
- AS IN PREVIOUS ANALYSES, BURN TIME IS CALCULATED CONSERVATIVELY BASED ON SHORTEST DISTANCE FROM CENTER OF VOLUME TO EDGE, BUT IS BASED UPON 3 FT/SEC FLAME SPEED o HYDROGEN BURNING WAS SUPPRESSED UNTIL A 4%
HYDROGEN CONCENTRATION THROUGHOUT THE CONTAINMENT WAS REACHED
GENEEIC_CLASIX:1_ ANALYSES o BASE CASE GENERIC CLASIX-3 ANALYSES WERE CONDUCTED USING PNPP AS THE REFERENCE PLANT 1
o BOTH THE SORV AND DWB TRANSIENTS WERE ANALYZED o DURING THE SORV TRANSIENT THE HYDROGEN BURNS WERE FAIRLY UNIFORM UP TO 21,000 SECONDS. AFTER 21,000 SECONDS BURNS OCCURRED AT ELEVATED HYDROGEN CONCENTRATIONS DUE TO LACK OF OXYGEN IN THE WETWELL
- PEAK TEMPERATURE DURING THE TAIL IN THE WETWELL WAS ON THE ORDER OF 700 DEGREES F
- BASE LINE TEMPERATURE IN THE WETWELL WAS ON THE ORDER OF 150 DEGREES F o DURING THE DWB CASE THERE ARE TWO LARGE PRESSURE AND TEMPERATURE RISES IN THE DRYWELL PRIOR TO 4,000 SECONDS. THE FIRST WAS DUE TO INITIAL BLOWDOWN, THE SECOND OCCURS AT REFLOOD i
PEAK TEMPERATURE IN THE DRYWELL DURING BLOWDOWN WAS APPROXIMATELY 320 DEGREES F l
l LONGTERM TEMPERATURE IN THE DRYWELL WAS APPROXIMATELY 250 DEGREES F l
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PEAK TEMPERATURE IN THE WETWELL WAS ON THE ORDER OF 700 DEGREES F BASE LINE TEMPERATURE IN THE WETWELL WAS ON THE ORDER OF 150 DEGREES F l
o THERE WERE NO BURNS IN THE DRYWELL DURING EITHER l TRANSIENT i
o 4
i EDIUBE_ ANALYSES o ADDITIONAL STUDIES ARE REQUIRED TO DETERMINE THE SENSITIVITY OF THE RESULTS TO SOME OF THE ASSUl:PTIONS UPON WHICH THE ANALYTICAL METHODOLOGY IS BASED o CONTAINMENT RESPONSE ANALYSIS DELAY INITIATION OF CONTAINMENT SPRAY BY 5 MINUTES DECREASE THE WETWELL SPRAY CARRYOVER FRACTION BY 1/2 INCREASE THE WETWELL SPRAY CARRYOVER FRACTION BY 2 DECREASE SHEET FLOW EFFECTIVENESS BY 1/2 DECREASE THE HYDROGEN RELEASE HISTORY TAIL TO O.05 LB/SEC
O J
EDTUBE_AEALYSES_.iccDhl DECREASE THE CHIMNEY FLOW AREA BY 1/2 USE PREVIOUS BURN PARAMETERS o DRYWELL BREAK ANALYSIS
- DECREASE IN MAAP MASS / ENERGY FOR DWB BASED ON MAAP BREAK SIZE FROM 4.84 TO 2.0 INCHES
- DELAY IN ADS TO MINIMUM ZERO INJECTION RPV WATER LEVEL TO SIMULATE STEAM COOLING i
I l - VARYING CGCS/ VACUUM BREAKER FLOW CHARACTER-ISTICS AND FLOW RATE i'
l
- ELIMINATE THE HEAT TRANSFER METHODOLOGY OF NUREG-0588 l
1
t l
l i
CDBCLUS10GB o CLASIX-3 COMPUTER PROGRAM WAS MODIFIED TO INCLUDE NATURAL CIRCULATION AND THE HEAT TRANSFER PROVISIONS OF NUREG-0588 o THE ANALYTICAL METHODOLOGY, CONSISTING OF THE CLASIX-3 COMPUTER PROGRAM AND THE SET OF GENERIC ASSUMPTIONS HAVE BEEN SHOWN TO RESULT IN CONSERVATIVE PREDICTIONS o CLASIX-3 HAS BEEN DEMONSTRATED TO BE ACCEPTABLE FOR USE TO DEFINE THE THERMAL ENVIRONMENT FROM HYDROGEN COMBUSTION FOR EQUIPMENT SURVIVABILITY ANALYSIS o REMAINING WORK COMPLETE THE SENSITIVITY STUDIES EVALUATE THE DRYWELL CONDITIONS AGAINST INVERTED DIFFUSION FLAME CRITERIA DETERMINE IF PLANT SPECIFIC ANALYSES ARE REQUIRED
s .
The effect of a range of steam releases to the drywell during hydrogen release should be investigated. The presently considered mass ratio of steam-to-hydrogen of 500/1 suppresses hydrogen burning in the drywell.
At the end of the meeting, HC0G said it would further investigate the secondary burn phenomenon. The final test report will address this phenomenon.
Sincerely, Oddest signed be Lester L. Kintner, Project Manager BWR Project Directorate No. 4 Division of BWR Licensing
Enclosures:
As stated DISTRIBUTION cc w/ enclosures: : Docket: File See next page NRC PDR LPDR PD#4 Rdg.
W8utler LKintner Young, 0GC EJordan BGrimes JHulman Glainas WHodges BLiaw MSrinivasan ACRS (10)
M0'Brien NRC Participants
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PD# /PM S PD#4/D ).
LKintner:lb an WButler y \J 07/J. /86 0 g/86 074f/86
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