ML19323G570
| ML19323G570 | |
| Person / Time | |
|---|---|
| Issue date: | 04/07/1980 |
| From: | Read J Office of Nuclear Reactor Regulation |
| To: | Bernero R NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| References | |
| NUDOCS 8006040453 | |
| Download: ML19323G570 (8) | |
Text
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APR 7 1999 MEMORANDUM FOR:
R. Bernero, Director, Probabilistic Analysis Staff THRU:
R. W.-Houston, Chief Accident Analysis Branch, CSE FROM:
J. B. J. Road, Accident Analysis Branch
SUBJECT:
WASH-1400 CORE MELT RELEASE FRACTIONS Appendix VII of WASH-1400 contains the description of the estimation of the amounts of fission product activities removed from a molten core by sparging with CO2 from concrete decomposition. The results of this estimation are contained in Table VII G-1 of WASH-1400, a copy of which is attached. Many of the entries in this table are absolutely astonishing and obviously wrong by many orders of nagnitude.
Uranium has the most' volatile compounds of any of the inner transition elements. This is a natural consequence of its ability to acquire the 6t oxidation state; and UF6 and U03 are easily volatilized, for example, while the rare earth fluorides and oxides are quite refractory.
Table VII G-1, however, claims uranium to be amongst the least volatile.
The WASH-1400 method estimates the core molt release by the equation:
release fraction = 1 - exp(1HVg/V ).
~
L where V /VL is the volume ratio between the CO2 gas which sparges the.
G melt and the volume of the melt itself. The " distribution coefficients".
H, are the ratios of the concentrations of each species in the gas and liquid phases. The equation itself is simply the integrated form of the.
first order depletion equation, and is so apparently right as to appear elegant, while the errors are subtle.
I will first discuss the likely errors due to the simplification itself and the choice of the wrong data base. The numerical effects of these two sources of error are difficult to quantify due to the sparseness of the data available.
What can be quantified is an error in the interpretation of the data in calculating H.
g
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R. Bernero 2
The two cases considered in Table VII G-1 are sparging by 20% m6100% of the CO2 released by the pyrolysis of 26.4 MT of concrete. Tha values of - 3 Vg/VL are 268 and 1340, respectivelfi m.i?h co Tespond t? HE0 and 35,400 m of gas. Two simplifying assumptions a. implicts in the WASH-1400 model:.
a) CO2 is itable at 3000K -
b) all species are congruent, Ne., they have the same average oxidation state in all phases i
f In reality, CO2 is strongly oxidizing at 3000K, being readily reduced to CO.
In addition, most of the evaporations are dominated by heterogeneous oxidation-reduction reactions. Th-reaction CO (g) + U0 (1) + C0(g) + UO (g) 2 2
3 is particularly favored. '
ANL-7867 is the reference cited for the " distribution coefficients" in Table VII G-1.
The particular table in ANL-7867 used can be readily identified by comparison of concentration ratios, and a copy of this
~
table is also attached. This table is one of many sample calculations appearing in Appendix C~of that report. These calculations are free energy minimizations meant to model the centers of LMFBR fuel rods during ccre disassembly accidents. The sample chosen for Table VII!G-1 is consistent with a system pressure of 160 atmospheres, highly reducing conditions, and an enormous enthalpy density. Sample calculations with much higher oxygen-to-metal ratios should have been chosen, and suitable correction made for the pressure difference.
~
The free energy minimization program described in ANL-7867 is designed to model the oxygen competition between uranium fuel and the fission j
products and to estimate vapor pressures. Since the exact solution to this problem is intractible, the authors simplified the constraint
" equations to remove volumes, introducing the term " smears density" for
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total system mass density. The algorithm requires three phases, an oxide, a metallic liquid, and a gas. The mole volume of the gas phase is strongly constrained by the ideal gas law, the oxide mole volume is weakly constrained by a. theoretical density equation, and the smaller amount of metallic phase is virtually an adjustable parameter. WASH-1400 simply ignores the distinction between the two liquid phases and applies the mole density of the 160 atmosphere gas to its approximately one atmosphere problem.
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R. Bernero 3
In the ANL-786/ calculation, the total pressure of 160 atmospheres is mostly due to a noble gas partial pressure of 108 atmospheres.
Alkalt metals and their oxides contribute 37.4aatm, iodine 6.2 atm, cadmium 5.0 atm, and tellurium 2.1 atm. The reason given for the high tellurima vapor pressure is simply that the library of free energies used by the code did not contain zirconates or tellurides, which are the stable high temperature species of this element.
As a calculation, the approximations in ANL-7867 are designed to conserva-tively estimate vapor pressures and chemical equilibria. For 100% sparging, WASH-1400 estimates 4.5% release of cesium metal and 1.7% release of cesium oxide (Ce2 3 in WASH-But the computed vapor pressure of Ce is 3.49 X 10 g400, Ce0 in ANL-7867).
0 atm, and that of Ce0 is 2.23 X.10-* atm.
Hence, WASH-1400 implies that cesium:is over three times as volatile as its
~
oxides, while the reverse is very much the case.
~
To use the ANL-7867 table correctly, the calculated vapor pressures should be used to calculate mole fractions at one atmosphere. At 3000K, 35, 400 m3 of inert sparge-gas would contain 1.43 X 105 moles of gas at one atmosphere.4 moles of cesium.When saturated with cesium metal vapor, this gas woul contain 5 X 10-In an end-of-life core there are about 1400 moles of cesium, so the fractional cesium release, assuming it to be in the metallic phase and undiluted by molten steel or zircalloy, would be 3.6 X 10-7, not 0.045. Under the same conditions 2.3% of the cesium oxide would be sparged, not 1.7%.
The vapor pressure of urani.. oxide is computed to be 0.144 atmospheres, hence to saturate 1.43 X 10 moles of gas would require 5.6 metric tons of fuel, and the fraction of uranium released ought to be 5% and not 0.6%.
ANL-7867 is consistent with the known chemistry of the inner transition
~
elements, while WASH-1400 is not.
The assumptions also include a constant temperature of 3000K. The formation of a gas from a condensed phase ~ at 3000K, by Traston's Rule, requires about 3 X 105 Joules per mold' The gas generations assumed, therefore, regiire of the order of 10" Joules. Variation of temperature and oxygen composition with time cannot be simply divorced from the assessment of fission product release, nor can energy balance. A great deal of the thermodynade data needed to estimate fission product release exists in ANL-7867, but WASH-1400 has not used it efficiently; since temperature and oxidation variation can be estimated roughly from use of the many other sample
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calculations.
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R. Bernero 4
In sumary. Table VII G-1 of WASH-1400 is grossly incorrect, and appears to have been used in assessing the radio-isotopic release fractions in the most severe of the core-melt accidents. Of the three sources of error in this table, the numerically most significant can be corrected by the methods outlined above, although tha errors from the other two sources are likely to be large.
I strongly suggest a review of the consequence assessments used by yourstaff to identify any conclusions which might be affected by the erroneous table.
-)
Ja Re d Accident Analysis Branch, Section A Division of Site Safety and Environmental Analysis, NRR cc:
A. Marchese M. Silbergerg M. A. Taylor J. Murphy R. DeSalva W. Houston ISTRIBUTION BCentral File -
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.q TABLE Vil G-1 REMOVAL OF FISSION PRODUCTS FROM MELT BY.SPARGING WITH CO2 FROM CONCRETE DECOMPOSITION Percent Sparge Gas Volume 20 100 Distributio Fission Product Coefficient b)
Fraction Removed from Melt
-2 A7 3.26 x 1.0
>0.999
>0.999 Ag2O 1.62 x 10~
>0.999
>0.999 BaI"I 9.35 x 10-
>0.999
> 0.'9 9 9 Ba0 4.09 x 10~
0.01 0.045 Cd 4.93
>0.999
>0.999
-2
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Cdo 3.45 x 10
>0.999
>0.993 Ce 4.14 x'10-$
0.01 0.045
-5 Ce2 3 1.25 x 10
<0.01 0.017 O
~1 Cs 6.51 x 10
>0.999
>0.999 Cs2O 1.53
>0.999
>0.999
~1 Eu 2.73 x 10
>0.999
>0.999
-3 Eu2 3 2.43 x 10 0.48 0.96 0
-3 Gd(a) 3.33 x 10 0.59
>0.999
-6 Gd 023 5.68 x 10
<0.01
<0.01 I
>0.999
>0.999 In 4.78 x 10~
>0.999
>0.999 In2 3 406.0
>0.999
>0.999 0
~4 La (a) 2.00 x 10 0.05 0.23 La2 3 3.67 x 10' O.01 0.051 0
Mo 3.35 x 10-
<0.001
<0.001
-4 moo 2 1.21 x 10 0.03 0.15
-0 Nb 2.47 x 10 E0.001
<0.001
~0 NbO2 2.92 x 10
<0.001
<0.001
~4 Nd(a) 9.65 x 10 0.23 0.73
~4 Nd 023 1.27 x 10
. 03 0.16
~4 Pd 6.12 x 10 0.15 0.56
~4 Pdo 3.80 x 10 0.10 0.40 I
Pm *I 8.84 x 10~
0.91
>0.999
-6 Pm2 3 3.25 x 10
<0.001 0.001 0
Pr(a) 1.03 x 10-0.24 0.75
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Pr2 3 1.38 x 10
<0.01 0.02 0
Rb 7.'53 x 10-1
>0.999
>0.999
-1 Rb 0 4.08 x 10
>0.999
>0.999 2
-5 Rh 2.06 x 10
<0.01 0.03 Rh 0 7.93 x 10-6
<0.01 0.01 2
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Ru 1.11 x 10
<0.01 0.02
-1 RuO 6.12 x 10
>0.999
>0.999 2
Sb 4.40 x 10~
>0.999
>0.999 Lb 023 8.80
>0.999
>0.999 VII-143 v
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i TABLE VII G-1 (Continued)
.l Percent Sparge Gas Volume 20 100 Distributio Fission Product Coefficient b)
Fraction Removed from Melt
-1 Se 4.49 x 10
>0.999
>0.999 SeO 4.10
>0.999
>0.999 2
I
-1 Sm ^I 3.24 x 10
>0.999
>0.999
-5 Sm2 3 5.45 x 10 0.01 0.07 0
Sn 4.02 x 10-0.66 0.995 SnO 3.62 x 10-
>0.999
>0.999 I
-1 Sr *I 2.45 x 10
>0.999
>0.999 Sr0 8.18 x 10-
<0.001 0.001 Tc 3.69 x 10-
<0.001
<0.001 II
-3 1.57 x 10 0.34 0.88 TcO2
-1 Te 0.62 x 10
>0.999
>0.999
-1 TeO2 3.40 x 10
>0.999
>0.999 I
-4 Y *I 3.45 x 10 0.056 0.384
-5 1.77 x 10 0.01 0.02 Y023 Zr 5.2 x 10-
<0.001
<0.001 ZrO2 1.59 x 10-
<0.001
<0.001
-6 UO2 4.71 x 10 0.001 0.006 PuO2 2.64 x 10-
<0.001
<0.001 (a)
Minor species (b)
Distribution coefficient = C rat ni 1 q id VII-130
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-62 TEMPERATURE = 30CO. CEGREES KELVIN BURNUP = 5.08 SMEAR DE h5 ITY = 5.0 GR AMS/CM*
- 3 P2 E-8UPNUP C/M RATIO = 1.9800 POST-BLRNUP O/M RATIC = 1 9924 PU/(U+PU) = 0.20 TCTAL PRESSLRE 1 6CD 02 ATMCSPHERES PIALKALI METALSi d= 3.740 01 ATMOSPHERES
=
PIC2)
= 2.4 5D-03 A TMO SPHERES P(NCSLE GASESI
%m 1.080 02 ATu0 SPHERES PIC)
= 5.560-03 ATPCSPbERES P(FutL SPECIES) 1.440-91 ATPOSPHERES
=
PEEDCMIN ANTLY OXIDIZED FISSICN PROCUCTS: B A, CE.E U, GD, LA, h8,ND, P M, PR, $M, SR, Y,2R,U, P U PRECCNINAhTLY MET ALL IC FISSICN PkOCUCTSt AG, CS,1N, PD,RB RU,5 8t SE, TC, TE MIXED FIS$lth PRCDUC15 2 C D, PO, R H, 5N GASECUS Fl!SICN PRODLCTS
- I,KR,XE CCNVERCEACE CbECK (C /M t INI TI All-C/ M t FINALi l**2 = 8.11D-13 T= 30CO.K BURNUP = 5.0%
PRE-SUR AUP C/ M = 1.98 PU/lU+PUI = 0.20 DENSITY = 5.
GM/CM**3 ELEMENT YIELC CONDENSED ACTIVITY CCNC.
SPOR PRESSURE CChC.
(MCLES/CCI PHAS E IMOLES/CC)
PHASE (ATM.)
(MOLES /CC)
SILVER 1.06C-05 AG1
- 1. 73 D-02
- 1. C 2 D-0 5 AG1 1.69D-01 3.32D-07 A G2-01 6.18D-08 1.13D-09 A G 1-01 9.31 D-05 1.830-10 EARILM 6.73C-05 BA1
- 9. 9 7 D-0 7
- 5. 8 8 D-10 BA1 2.79D-05 5.500-11 B A l-01 3.670-03
- 6. 73 D-05 BAl-C1 1.400-03 2.75D-09 BAl-02 1 16D-06 2 13 D-C 8 CACMIUM 1.230-05 CD1 3.38D-03
- 1. 99 D-06 CD1 4.990 00
- 9. 8 2 D- 06 C DI-01
- 2. 64 D-0 5 4.84D-07 CD1-01
- 8. 46 D- 03 1.670-08 CERIUM 1 260-04 CE1
- 2. 82 D-07 1.66D-10 CE1 3.49D-09 6.880-15 C E 2-03 1.90D-03
- 3. 4 8 D- 0 5 CEl-01 2.23D-04 4.380-10 CEl-02 3.10D-03
- 1. 64 D-01 9,69 D- 0 5 CSI 3.200 01 6.310-05 CS2-01
- 4. 71 D-05 8.64D-07 CS2 1.490 00 2.940-06 CS2-02
- 4. 60 D-08
- 8. 4 3 D-10 CSI-01 1.910-01 3.76D-07 CS2-03
- 2. 710-11
- 4. 9 7 D-13 CS2-01 6.700-02 1.32D-07 CSI-02
- 2. 5 S D-05
- 4. 73 D-C 7 EUROPIUM 6.57C-06 EU1
- 2. 39 D-07 1.410-10 EU1 1.95D-05 3.850-11 EU2-03
- 1. 79 D-04 3.28D-06 EU1-01 4.C4D-03 7.960-09 GACCL1blup 4.63C-06 GDI 7.07D-09 4.170-12 GD1 7.060-09 1.390-14 GD2-03
- 1. 26 D-04 2.310-C6 GD1-01 6.450-06 1.310-11 1CCINE 1.230-05 12 0.0 0.0 I 1 6.160 00 1.21D-05 I 2 4.49D-02 8.840-08 thCIUM 6.48C-07 INI 1.CSD-03 6.18 D- 0 7 INI 1.500-02 2.950-08 IN2-03 1.250-11
- 2. 3 CD-13 INI-01
- 4. 7 4 D-C5
- 9. 3 4 D-11 IN2-01 3.440-06 6.77D-12 KRYPTCh 1.95C-05 KR1 3.700-36 2.180-39 KR1 9.920 00 1.9 5 0-C 5 LANTHAAUP 5.02C-05 LA1
- 3. 60 0-C8 2.12 D-11 LAI 2.16 D-09 4.25D-15 LA2-03
- 1. 37 D-03 2.51D-05 LAl-01 4.68D-04 9.23D-10 FCLYBDENLM 1.050-04 N01
- 3. 5 8 D-02 2.11 D- 0 5 M01 3.58D-06
- 7. rod-12 PCI-02
- 5. 70 D-0 3 1.040-04 M01-01 2.27D-05 4.47D-11 N01-03
- 3. 22 D- 03 5.900-05 M01-02 6.41D-03 1.2 6 0-C 8 M01-03
- 5. 04 D-0 3 9.92D-09 N02-06 3.86D-07 7.610-13 N01-09
- 1. 01 D-11 1.990-17 b!OBIUP 6.2CC-C6 N81 1.18 D-0 6 6.960-10 NB.
8.72D-12 1.72D-17 N81-01 1.05D-04" 1.9 3 D- 0 6 NB1-01 6.07D-06 1.200-11 N81-02
- 2. 2 4 D-04 4.10D-06 N81-02 6.710-07 1.320-12 N02-05 4.69D-06 8.60D-08 NEODYMIUM 1.450-04 ND1 3.280-07 1.93D-10 ND1
- 9. 4 6 D-0 8 1.86D-13 N O2-03
- 3. 9 7 D-0 3
- 7. 2 7 D- 0 5 NDI-01 4.680-03 9.22D-C9 PALLADIUM 1.330-04 PD1
- 2. 24 D-01
- 1. 3 2 D- 04 PD1 4.10D-02 8.07D-C8 PD1-01 3.13D-05 5.82D-07 PDI-01 1.12D-04 2.210-10 PD1-02
- 2. C 7 D-0 7
- 4. 0 9 D-13 PRCFETFIUP 1.43C-05 PMt 7.920-10
- 4. 67 D-13 PM1 2.10D-09 4.13D-15 P "2-03 3.890-04 7.13 D-0 6 P M1-01 1.18 D- 05 2.320-11 PRAESEC0YPIUM 4.430-05 PRI
- 3. 65 D-09 2.150-12 PRI 1.12D-09 2.21D-15 PR2-03 1.190-03 2.16 D-05 PRL-01 1.51D-04 2.980-10 P R 1-0 2
- 5. 99 D- 05 1.100-06 RLDIDIUM 1.6ED-05 RB1 1.60D-02
- 9. 4 7 D- 06 RBI 3.620 00 7 13D-06 R S2-01 2.300-06 4 220-08 RB2 1.240-02 2.440-08 R82-02 4.40D-09 8.06D-11 R 81-01 8.79D-03 1.73D-08 R 82-0 3 3.280-12
- 6. C 1 D-14 R81-02
- 5. 61 D-06 1.C3D-07 4
E
l 63 i
T = 3000.K BURNUP = 5.03 PRE-8URNUP O/M 1.98 PU/(U+Put = 0.20 DENSITY = 5. GM/CM**3
=
i ELEMENT YIELD COND EN SE D ACTIVITY CCNC.
VAPCR PRESSURE CONC.
INCLES/CC)
PH AS E IMOLES/CC)
PHASE IATM.)
IMOLES/CCI t
RHODIUM 4.060-05 RH1
- 5. 61 D-02
- 3. 31 D-0 5 RH1 3.460-04 6.810-10 i
R H2-01
- 1. 72 D-04 3.15D-06 RH1-01 1.270-05 2.500-11 RH1-01 6.81D-05 1.250-06 RH1-02
- 7. 35 D-0 7 1.450-12 R H2-0 3 5.97D-14 1.C9D-15 RtTHENIUM 2.130-04 Rui 3.600-01 2.13 D- 04 RU1 1.18D-03 2.33D-C9 R U1-02 6.52D-08 1.200-09 RU1-01 3.730-04 7.350-10 RU1-02 9.89D-05 1.95D-10 RU1-03 4.790-07 9.430-13 RU1-04 2.98D-11 5.880-17 A h T I MC NY.
2.SSC-06
$81 4.200-t3 2.480-06
$81 5.51D-02 1.090-07
$82-03 1.76D-05 3.22D-10 582 4.39D-04 8.660-10 582-04 1.35D-19 2.480-16 584 2.02D-10
- 3. 9 7 D-16 S82-05 1.460-17 2.67D-19 181-01 1.44D-03 2.830-C9 584-06 2.000-24 3.94D-30 SELENIUM 4.2 6 D-06 SE1
- 4. 77 D-03 2.810-06 SE1 6.41D-01 1.260-06 S E 1-02 1.320-10 2.420-12 SE2 3.080-02 6.080-08 SEl-01
- 3. 23 D- 02 6.36D-C8 SEl-02 5.13 D-06 1.01 D-11 SAMARILM
- 4. 0 C D-0 5 SM1 6.92D-09 4.C80-12 SM1 6.690-07 1,320-12 S M2-0 3 1.C9D-03
- 2. C 00-0 5 S M I-O '.
5.12D-04 1.010-09 TIN 6.760-C6 SN1
- 5. 81 D-03 3.43D-C6 SN1 7.C00-03
- 1. 3 80- C 8
$N1-01
- 1. 50 D-04 2.750-06 SN1-01 5.070-02 9.98D-08 S N1-02
- 2. 56 D-0 5
- 4. 70 D- 0 7 STRCNTIUM 4.c40-05 SR1 2.C60-07 1.220-10 SRI 1.51D-05 2.9E?-11 S R1-01 2.20D-03
- 4. C3 D- 05 SRI-01 1.67D-05 3.300-11 SR1-02 1.C10-06 1.85D-C8 TECHNETIUM 4.02C-05 TC1
- 6. 79 D-02 4.010-05 TC1 7.52D-06 1.48D-11 T C1-02 6.200-06 1.14 D-0 7 TC1-01 4.840-05 9.540-11 Y C 1-0 3
- 1. e 4 D-10
- 3. 01D-12 TC1-02 9.090-05 1.79D-10 TC2-07 1.58D-21 2.900-23 T C 2-0 7 '
4.13 D-22 8.14D-28 TELLURIUM 2.820-05 TE1 4.05D-02 2.390-05 TE1 1.970 00 3.870-06 TEl-02 1.780-06
- 3. 2 6 D-C 8 TE2 1.03D-01 2.030-C7 TEl-01 5.64D-03 1.11D-08 XENCN 1.940-04 XE1 3.68D-35 2.17D-38 XE1 9.850 01 1.940-04 VTTRIUM 2.050-05 Y 1
- 9. 7 3 D- 0 8
- 5. 74D-11 Y 1
- 1. C3 D- 0 8 2.030-14 Y 2-03 5.58D-04 1.02D-05 Y 1-01 9.18D-05 1.81D-10 ZIRCCNIUP 1.960-04 ZR1 1.870-09 1.100-12 ZR1 2.900-13 5.72D-19 ZR1-02 1.07D-02 1.96D-04 ZR1-01 3.84D-08 7.57D-14 ZR1-02 1.58D-06 3.120-12 URAN!UP 1.410-02 U 1-02
- 7. 68 D-01
- 1. 41D- 02 U1 8.690-11 1.710-16 U 1-01 6.490-06 1.28D-11 U 1-02 3.38D-02 6.650-08 U 1-03 1.100 01 2.17D-07 PLUTCNIUM 3.520-03 P U1-0 2 1.S2D-01 3.520-03 PU1 8.37D-09 1.650-14 PU1-01 4.38D-05 8.640-11 PU1-02
- 4. 73 D-04 9.32D-10 i
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