ML19350D289
| ML19350D289 | |
| Person / Time | |
|---|---|
| Issue date: | 03/17/1981 |
| From: | Kuhlman M NRC - PEER REVIEW GROUP |
| To: | |
| Shared Package | |
| ML19350D284 | List: |
| References | |
| NUDOCS 8104150146 | |
| Download: ML19350D289 (17) | |
Text
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O 6.
FISSION PRODUCT TRANSPORT IN PRIMARY SYSTEM TO CONTAINMENT f
PRESENTED BY MICHAEL R. KUHLMAN TO PEER REVIEW CROUP FOR NRC REPORT ON TECHNICAL BASES FOR ESTIMATING FISSION PRODUCT BEHAVIOR DURING LWR ACCIDENTS MARCH 17 AND 18, 1981 8164150lk
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FISSION PRODUCT TRANSPORT IN PRIMARY SYSTEM TO CONTAINPENT El THE TRAP-MELT CODE E l UNCERTAINTIES ASSOC 4ATED WITH TRAP-MELT PREDICTIONS EJ. TRAP-MELT ACCIDENT ANALYSES E d EFFECTS OF IODINE SPECIES DISTRIsuTION Ed PRIMARY SYSTEM RETENTION OF NON-IODINE FISSION PR0cuCTS E d
SUMMARY
AND CONCLUSIONS
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Etl THE TRAP-MELT CODE TRAP-MELT IS A DYNAMIC, MECHANISTIC CODE.
THE MAJOR PROCESSES CONSIDERED INCLUDE:
4 SOURCE TERMS FOR SPECIES IN VOLUMES 9
CONDENSATION AND EVAPORATION OF VAPORS 9
SORPTION OF VAPORS 9
PARTICLE DEPOSITION:
INERTIAL DIFFUSIVE, THERMOPHORETIC COAGULATION IS NOT CONSIDERED IN THE ANALYSES PRESENTED.
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6.3 ORIGEN Core Inventory
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1 Source Tem Estimates Plant and Accident Specific Factors V
y MARCH, RELAP TRAP-MELT Thermal Hydraulic Primary System 4
Physico-Chemical Data conditions Penetration I
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Contairmient Atmosphere Radionuclide Concentrations Y
CRAC Release to Environment and Atmospheric Dispersion FIGURE 6-1.
FLOW DIAGRAM OF RELATIONSHIPS AMONG RISK ASSESMENT CODES 1
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6.
FISSION PRODUCT TRANSPORT IN PRIMARY SYSTEM TO CONTAINMENT 6.1 THE TRAP-MELT CODE 621 UNCERTAINTIES ASSOCIATED W!TH TRAP-MELT Pa~EDICTIONS e
THERMAL-HYDRAULIC DATA DURING MELTDOWN e
SOURCE RATES OF NUCLIDES e
SOURCE RATES OF STRUCTURAL MATERIALS e
PHYSICO-CHEMICAL FORMS OF FISSION PRODUCTS f
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FISSION PRODUCT TRANSPORT IN PRIllARY SYSTEM
.T0 CONTAINMENT 6.1 THE TRAP-MELT CODE 6.2 UNCERTAINTIES ASSOCIATED WITH TRAP-MELT PREDICTIONS 6.3 TRAP-MELT ACCIDENT ANALYSES 6.3.1 SEQUENCES INVOLVING MINOR OR NO FUEL DAMAGE 6.3.2 SEVERE CORE DAMAGE SEQUENCES 8
DEGRADED CORE SEQUENCES e
CORE MELTDOWN SEQUENCES l
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6,3,1 SEQUENCES INVOLVING MINOR OR No Fuet DAMAGE e
LARGE PIPE BREAK IN THE COLD-LEG OF A PWR, ECC RECOVERS CORE BEFORE MELTING STARTS e
FLOW PATHS TO CONTAINMENT e
RESULTS OF TRAP ANALYSES (SASE CASE)
- 53% OF ELEMENTAL IODINE RELEASED
- 1% OF CSI RELEASED e
INFLUENCING PARAMETERS
- STEAM FLOW RATE
- SYSTEM TEMPERATURES
- PARTICLE SOURCE l
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STE A M STEAM GEN ERATOR GENERATOR a
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T ~ 270 F T ~ 450 F p
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CORE AND 200 fps LOWER PLENUM
- 7 ECC WATER-STEAM MIXING REGION STEAM I
CONTAINMENT FIGURE D.I.
FLOW PATitS, FLUID VELOCITIES, AND SYSTEM TEMPERATURES FOR A SEQUENCE INVOLVING LITTLE OR NO FUEL DAMAGE IN A PWR (SECTION 6.3.1) l (T Denotes Surface Temperature T Gas Temperature) s i
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6.3.2 SEVERE CORE DAMAGE SEQUENCES e
DEGRADED CORE SEQUENCES (1) STUCK OPEN RELIEF VALVE, PARTIAL ECC OPERATION
- NO DRY PATHWAY TO CONTAINMENT
- INSOLUBLE GASES ONLY CLASS OF FISSION PRODUCTS NOT RETAINED IN PRIMARY SYSTEM WATER (2) LARGE PIPE BREAK, DELAYED ECC INJECTION (AD-1/2)
- 1/2 0F CORE MELTS
- DRY PATHWAY TO CONTAINMENT FOR PART OF ACCIDENT
- OVER 99% OF ELEMENTAL IODINE RELEASED
- 82% OF CSI RELEASED l
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I 6.3.2 SEVERE CORE DAMAGE SECUENCES e DEGRADED CORE SEQUENCES S CORE MELTDOWN SEQUENCES (1) IRANSIENT WITH LOSS OF HEAT REMOVAL (PWR)
(2) LARGE PIPE BREAK WITH FAILURE OF ECC (PWR)
(3) TRANSIENT WITH FAILURE TO SCRAM (BWR)
(4) LARGE PIPE BREAK WITH FAILURE OF ECC (BWR) m l
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CORE MELiDOWN SEQUENCES (1) TRANSIENT WITH LOSS OF HEAT DEMOVAL (PWR)
RETENTION (%)
IODINE M
e BASE CASE (TMB'-1)
<0.1 6.9 e LARGE SIZE PARTICLE SOURCE
<0.1 6.8 (TMG'-2) e 'dEAK PARTICLE SOURCE
<0.1 9.6 (TMB'-3) e ALTERED THERMAL-HYDRAULICS
<0.1 37.2 (TMB'-4) i l
CORE MELTDOWN SEQUENCES i
(2)
LARGE PIPE BREAK WITH FAILURE OF ECC (PWR)
RETENTION (%)
IODINE M
e BASE CASE (AD-1)
<1.0 18.2 e LARGE SIZE PARTICLE
<l.0 24.5 SOURCE (AD-2) e WEAK PARTICLE SOURCE
<l.0 61.2 (AD-3) e ALTERED THERMAL HYDRAULICS
<1.0 65.7 (AD-4)
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CORE MELTDOWN SEQUENCES (3)
TRANSIENT wiTy FAILURE TO 3CPAM (EWR)
S IODINE RETENTION:
5.3% IN STEAM DRYERS e
CSI RETENTION:
46.6-83% IN STEAM SEPARATORS (4)
L>aar Pipe B=Es< wrTH FArLURE OC ECC (3WR) o IODINE RETENTION:
<0.1%
e CSI RETENTION:
~10.9%
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1 6.
FISSION PRODUCT TRANSPORT IN PRIMARY SYSTEM TO CONTAINMENT 6.1 THE TRAP-MELT CODE 6.2 UNCERTAINTIES ASSOCIATED wtTH TRAP-MELI PREDICTIONS 6.3 TRAP-MELT ACCIDENT ANALYSES 6th EFFECTS OF IODINE SPECIES DISTRIBUTION e
NEAR THE CORE, THE SPECIES DISTRIBUTION IS DIFFICULT TO ASSESS, DUE TO THE HIGH TEMPERATURES.
e AS THE GAS LEAVES THE CORE REGION, THE TEMPERATURES SHIFT TOWARDS FAVORING CSI AS THE PREVALENT SPECIES.
e POSSIBLE EXCEPTION MAY OCCUR FOR A HOT LEG BREAK.
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6.
FISS10fl PRODUCT TRANSPORT Ill PRIMARY SYSTEM TO CONTAINMENT E d PRIMARY SYSTEM RETENTION OF NON-IODINE FtSSION PRenuCTS e
HIGHLY VOLATILE SPECIES SHOULD BEHAVE LIKE IODINE IN THESE ANALYSES.
RETENTION WILL BE MINIMAL IN DRY SYSTEMS, DEPENDS ON SOLUBILITY
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AND CONTACT IN WET ONES.
e NON-VOLATILE SPECIES WILL RECONDENSE AS PARTICULATE MATTER AND BE TRANSPORTED THROUGH THE SYSTEM AS SUCH.
RETENTION IS EXPECTED TO RANGE FROM <1 TO AS MUCH AS 20% FOR DRY SYSTEMS.
e SPECIES OF INTERMEDIATE VAPOR PRESSURE WILL EXHIBIT THE BEHAVIOR OF CSI IN THE ABOVE ANALYSES.
RETENTION IS QUITE VARIABLE, AND INFLUENCED BY THERMAL HYDRAULICS AND AEROSOL SOURCE CHARACTERISTICS.
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6.
FISSION PRODUCT TRANSPORT IN PRIMARY SYSTEM TO CONTAINMENT E l
SUMMARY
AND CONCLUSIONS e
ELEMENTAL IODINE IS NOT RETAINED IN A DRY SYSTEM, AND EXTENT OF RETENTION IN WATER DEPENDS ON EFFICIENCY OF CONTACT.
e CSI RETENTION IS VERY HIGH FOR SEQUENCES WHICH ARE WATER BOUNDED.
e CSI RETENTtON IN CORE MELT SEQUENCES RANGES FROM ALMOST NONE TO AS MUCH AS 80% UNDER CERTAIN CONDITIONS.
e BASED ON PREVIOUS CHAPTER, AND THERMAL-HYDRAULICS PERTINENT TO ABOVE ACCIDENTS, CSI IS THE PRINCIPAL FfSSION PRODUCT IODINE SPECIES.
e PARTICLE RETENTIOR IS VERY HIGH FOR THE SEQUENCE WITH MINOR FUEL DAMAGE, AND FOR WATER BOUNDED SEQUENCES.
e PARTICLE RETENTION IS VARIABLE FOR MELT SEQUENCES, AND MAY BE HIGH FOR SEQUENCES WITH VERY LOW STEAM FLOW RATES.
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